JP2010023402A - Aluminum support for lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate for lithographic printing plate which can be used as a CPT lithographic printing plate material hardly causing plate slippage in newspaper offset color printing by means of a high-speed rotary press, and to provide an aluminum support for lithographic printing plate used for the manufacturing of the original plate for lithographic printing plate. <P>SOLUTION: The aluminum support for lithographic printing plate is obtained by roughening the surface of aluminum alloy plate, wherein a tensile strength in the tensile test (tensile speed: 2 mm/min) according to JIS Z2241 of the aluminum support after the roughening is 170 to 225 MPa. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermal negative type or thermal positive type lithographic printing plate precursor capable of direct drawing with an infrared laser beam without using a lith film, and high-speed plate making, and an aluminum support for a lithographic printing plate used for the lithographic printing plate precursor About.

Conventionally, as a lithographic printing plate precursor, a photosensitive lithographic printing plate (PS plate) having a constitution in which an oleophilic photosensitive resin layer is provided on a hydrophilic support is widely used. After mask exposure (surface exposure) through the film, the desired printing plate was obtained by dissolving and removing the non-image area.
In recent years, digitization techniques that electronically process, store, and output image information using a computer have become widespread. Various new image output methods corresponding to such digitization techniques have come into practical use. As a result, computer-to-plate (CTP) technology that scans highly directional light such as laser light in accordance with digitized image information and directly manufactures a printing plate without going through a lith film is eagerly desired. Therefore, obtaining a lithographic printing plate precursor adapted to this is an important technical issue.

In recent years, color printing has been increasingly used in the field of newspaper printing, which is an example of an industry that produces printed materials in large quantities. In general, AM screens and FM screens are used as color printing methods in newspaper printing.
Color printing is generally created by sequentially superposing and printing four color images of cyan, yellow, magenta, and black. Therefore, it is necessary to print the image without shifting, and overprinting by accurate registration (positioning of each of the four color plates) is required.

Up to now, it has been said that color misregistration due to misregistration generally does not occur in a lithographic printing plate using a metal such as aluminum as a support. However, in newspaper offset color printing using a high-speed rotary press, color misregistration due to misregistration often occurs. In particular, color printing using an FM screen has a problem that the influence of this color shift is large because of high resolution.
One cause of such color misregistration is the misalignment of the plate that is folded to attach to the plate cylinder due to friction with the blanket that rotates at high speed. It is estimated that a color shift occurs due to the shift.

In Patent Document 1, as a countermeasure against plate misalignment, the tensile strength and the proof stress in a tensile test (tensile speed: 2 mm / min) are 16.5 to 18.5 kg / mm ² (162 to 181 MPa), respectively. A lithographic printing plate material for CTP having an aluminum support and a photosensitive layer provided on the lithographic printing aluminum support is described.
However, the aluminum support having the characteristics described in Patent Document 1 is insufficient for a support having a high average surface roughness Ra and a high specific surface area, which is excellent in scratch resistance and printability.

  Furthermore, recently, with the advance of printing technology, the printing speed has increased, and in response to the increase in stress applied to the printing plate that is mechanically fixed to both sides of the plate cylinder of the printing press, When the strength requirement is increased and the support strength is insufficient, the fixing portion is deformed or broken to cause troubles such as printing misalignment. Therefore, it is essential to improve the strength of the support.

JP 2008-105227 A

  The present invention solves the above-described conventional problems, and a lithographic printing plate precursor that can be used as a lithographic printing plate material for CTP with little plate displacement in newspaper offset color printing by a high-speed rotary press, and the lithographic printing An object of the present invention is to provide an aluminum support for a lithographic printing plate used for producing a plate precursor.

  In order to achieve the above object, the present invention provides an aluminum support for a lithographic printing plate obtained by roughening the surface of an aluminum alloy plate, the JIS for the aluminum support after the roughening treatment. Provided is an aluminum support for a lithographic printing plate having a tensile strength of 170 to 225 MPa in a tensile test (tensile speed: 2 mm / min) according to Z2241.

  In the aluminum support for a lithographic printing plate of the present invention, the arithmetic average surface roughness Ra of the surface of the aluminum support is more preferably 0.35 to 0.65 μm.

The present invention also provides a photosensitive lithographic printing plate precursor comprising an image recording layer provided on the lithographic printing plate aluminum support of the present invention.
Here, it is particularly preferable that the image recording layer is a layer sensitive to a semiconductor laser of 830 nm.
The image recording layer is particularly preferably a thermal negative type image recording layer.

  By using the lithographic printing aluminum support of the present invention for a CTP lithographic printing plate material, it is possible to provide a printed matter having a good image without color shift in newspaper offset color printing by a high-speed rotary press. According to the present invention, it is possible to provide a lithographic printing plate material for CTP which has little printing error, excellent printing performance, and excellent scratch resistance on the surface of the image recording layer.

The aluminum support for lithographic printing of the present invention is an aluminum support for a lithographic printing plate obtained by roughening the surface of an aluminum alloy plate, and is a tensile test according to JIS Z2241 after the surface roughening treatment ( The tensile strength (hereinafter simply referred to as “tensile strength” in this specification) at a tensile speed of 2 mm / min is 170 to 225 MPa.
If the tensile strength is 170 MPa or less, plate misalignment is likely to occur, and if it exceeds 225 MPa, it is difficult to bend the plate for attachment to a rotary press.
Further preferable tensile strength is 185 to 210 MPa, particularly preferably 190 to 205 MPa.

Furthermore, the aluminum support for lithographic printing of the present invention has a 0.2% proof stress (hereinafter referred to as “0. 0” in the tensile test (tensile speed: 2 mm / min) according to JIS Z2241 after the surface roughening treatment). 2% yield strength ") is preferably 155 to 225 MPa. Further preferable 0.2% proof stress is 160 to 210 MPa, particularly preferably 170 to 195 MPa.
If the 0.2% proof stress is 155 MPa or less, plate misalignment is likely to occur, and if it exceeds 225 MPa, it may be difficult to bend the plate for attachment to a rotary press.

Furthermore, the lithographic printing aluminum support of the present invention preferably has a region where the relationship between 0.2% proof stress and tensile strength is represented by the following formula (1).
0.2% yield strength <Tensile strength x 0.76 + 40 ... Formula 1
More preferably, it is a region represented by the following formula (2).
0.2% yield strength <Tensile strength x 0.76 + 35 ... Formula 2
Particularly preferred is the region represented by the following formula (3).
0.2% yield strength <Tensile strength x 0.76 + 33 ... Formula 3

  Further, the lithographic printing aluminum support of the present invention preferably has an elongation specified by JIS Z2241 and Z2201 of 1 to 10%.

  The aluminum support for lithographic printing according to the present invention preferably has an average surface roughness Ra of 0.35 to 0.65 μm, particularly roughened to 0.40 to 0.60 μm. It is preferable that the support is made. By setting Ra to 0.35 μm or more, scratch resistance is improved. On the other hand, if it exceeds 0.65 μm, the antifouling performance decreases.

[Aluminum alloy plate]
The composition of the aluminum alloy plate (hereinafter simply referred to as “aluminum alloy plate”) used for the lithographic printing aluminum support of the present invention is not particularly limited, but Si: 0.03 to 0.15%, Fe: 0.2 -0.7%, Cu: 0.00-0.05%, Mg: 0.01-0.4%, Ti: 0.003-0.5%, Mn: 0.000-1.5% It is preferable that the composition is contained and the balance is made of aluminum and inevitable impurities.
The significance and reasons for limitation of the components contained in the aluminum alloy sheet will be described.

  Si coexists with Fe to form an A1-Fe-Si-based metal intermetallic compound, and the dispersion of the compound refines the recrystallized structure. The formation of pits during the conversion process is made uniform and the pits are finely distributed. The preferable content of Si is in the range of 0.03 to 0.15%. If it is less than 0.03%, the distribution of the compound becomes non-uniform, and an unetched part is generated during the electrolytic surface-roughening treatment, which may make pit formation non-uniform. If it exceeds 0.15%, a coarse compound is produced, and precipitation of simple substance Si tends to occur, which may reduce the uniformity of the roughened structure.

  Fe forms an A1-Fe-based intermetallic compound, and coexists with Si to form an Al-Fe-Si-based intermetallic compound. The dispersion of these compounds refines the recrystallized structure. The compound becomes the starting point of pit generation, and the formation of pits is made uniform during the electrolytic surface roughening treatment, and the pits are finely distributed each time. The preferable content of Fe is in the range of 0.2 to 0.7%. If it is less than 0.2%, the distribution of the compound becomes non-uniform, and unetched portions are generated during the electrolytic treatment, which may make the formation of pits non-uniform. If it exceeds 0.7%, a coarse compound is produced, and the uniformity of the roughened structure may be lowered.

Most of Mg functions as a solid solution in aluminum to improve strength and heat softening resistance. Further, Mg acts to suppress the precipitation of simple Si, which reduces the uniformity of the roughened structure by forming a Mg—Si compound (Mg ₂ Si).
The strength is the tensile strength at the limit as a printing plate support. As described above, the aluminum support for a lithographic printing plate of the present invention has a tensile strength of 170 to 225 MPa.
Heat softening resistance is also called burning resistance, and is 0.2% proof stress after heating at a temperature of about 280 ° C. The aluminum support for a lithographic printing plate of the present invention has a 0.2% proof stress of 100 to 225 MPa after being heated at a temperature of about 280 ° C. A preferable content of Mg is in the range of 0.01 to 0.4%. If the Mg content is less than 0.01%, sufficient tensile strength and 0.2% proof stress may not be obtained. There is a possibility of causing a scratch failure on the surface of the aluminum alloy plate, which is not preferable.
The Mg content is more preferably 0.03 to 0.20%, most preferably more than 0.05% to less than 0.10%.

In an aluminum alloy containing Mg, an oxide film mainly composed of Mg oxide (MgO-based oxide) is easily formed by heat treatment such as homogenization treatment or heating during hot rolling. Moreover, since it is porous, the wettability with the treatment liquid is improved in the electrolytic surface roughening treatment, and the surface roughening is promoted. In order to obtain this effect, it is preferable that the Mg concentration in the surface layer portion from the surface of the aluminum alloy plate to a depth of 0.2 μm is 5 to 50 times the average Mg concentration. If it exceeds 50 times, the roughening proceeds excessively and the pits tend to be non-uniform. Mg has the effect of improving the tensile strength and proof stress of the aluminum plate.
Further, Mg in solid solution promotes roughening, and precipitation of the Mg—Si based compound (Mg ₂ Si) suppresses precipitation of simple Si that lowers the uniformity of the roughened structure. The amount of Mg precipitated in the matrix of the aluminum-containing metal plate is preferably 50% or less of the average Mg concentration, and when the solid solution and precipitation of Mg are in this ratio, preferable roughening can be achieved. It becomes possible.

  Ti refines the ingot structure and refines the crystal grains. As a result, the formation of pits during the electrolytic treatment is made uniform, and the occurrence of a streak when the printing plate is processed is prevented. The preferable content of Ti is in the range of 0.003 to 0.05%. When the content is less than 0.003%, the effect is small. When the content exceeds 0.05%, an Al—Ti-based coarse compound is generated, and the roughened structure tends to be uneven. In addition, in order to make the ingot structure fine, it is preferable to contain Ti in a range of 0.01% or less in the hoisting in which B is added together with Ti.

Cu easily dissolves in aluminum, and has an effect of refining pits with a content of 0.05% or less. Cu contained in the aluminum alloy plate is preferably 0.00 to 0.05%, particularly preferably 0.01 to 0.02%.
If it exceeds 0.05%, the pits at the time of electrolytic treatment are likely to be coarse and non-uniform, and unetched portions are likely to occur. In addition, the amount of Cu mixed from the bare metal employed for obtaining the above-described Fe and Si contents is about 5 to 100 ppm (0.0005 to 0.01%).

  Mn has a function of improving the tensile strength and proof stress of the aluminum alloy plate and can be added in an amount of 0.000 to 1.5%. Mn oxide or hydroxide is used as sludge in the alkaline solution. Since it precipitates and contaminates the roughening treatment step of the aluminum alloy plate, it is preferably 0.05% or less, particularly 0.01% or less from the viewpoint of the stability of the roughening process.

  The balance of the aluminum alloy plate is made of aluminum (Al) and inevitable impurities. Most of the inevitable impurities are contained in the aluminum ingot. If the inevitable impurities are contained in, for example, a metal with an aluminum purity of 99.7%, the effects of the present invention are not impaired. For inevitable impurities, see, for example, L.A. F. The amount of impurities described in Mondolfo's “Aluminum Alloys: Structure and properties” (1976) and the like may be contained. Examples of inevitable impurities contained in the aluminum alloy plate include Zn, Ti, B, Ga, and Ni.

Zn is contained in a very small amount in the new metal. Zn is relatively easily dissolved in an aluminum alloy. Zn affects the electrochemical surface roughening property of the aluminum alloy plate. In the present invention, the Zn content is preferably 0.05% or less, particularly preferably 0.01% or less.
B may be added together with Ti as a crystal refining material. In the present invention, the content of B is preferably 0.05% or less, and particularly preferably 0.04% or less.
Both Ga and Ni may be contained in trace amounts as impurities in the metal. Each content is preferably 0.05% or less, particularly preferably 0.03% or less.

The aluminum alloy sheet preferably has an average recrystallized grain size in the direction orthogonal to the rolling direction of the surface layer portion of 0.05 mm or less, and further has a crystal length stretched in the rolling direction of the surface layer portion. It is preferable that it is 0.3 mm or more. Here, the surface layer portion means a depth of 25% from the surface layer with respect to the total thickness of the aluminum alloy plate.
The average recrystallized grain size in the direction perpendicular to the rolling direction of the surface layer is preferably 0.01 to 0.05 mm, particularly preferably 0.02 to 0.04 mm.
The length of the crystal stretched in the rolling direction of the surface layer is preferably selected from the range of 0.3 mm to 200 mm (fiber form), more preferably 0.3 to 2.0 mm, and 0.5 to 0.9 mm is particularly preferable. If the elongated crystal length exceeds 200 mm, the surface quality after the roughening treatment may be deteriorated. If it is less than 0.3 mm, the tensile strength of the aluminum is difficult to be desired.

  As a method for confirming crystal grains, a general macro-etching method can be used. As an etchant for observing crystal grains, an aqueous solution of hydrofluoric acid, an aqueous solution in which a plurality of acids are mixed, or the like can be used. The observation of the crystal grains is particularly preferably performed by taking a photograph of a sample etched with an aqueous solution of hydrofluoric acid after mirror polishing and using an optical microscope using a polarizing filter. Using this photograph, the width and length of the crystal grains can be measured, and the average value and the maximum value can be obtained.

The aluminum alloy plate preferably has the following cross-sectional shape.
Usually, an aluminum plate is stored for a predetermined period while being wound as a coil. In the cross section of the plate, if the thickness of the end of the plate, i.e., the ear, is too thick, the thick portion undergoes plastic deformation while being wound in a coil shape for several thousand meters and is called ear distortion. Distortion occurs. Similarly, if the inner thickness of the plate is too thick, plastic deformation occurs, and an inner strain called abdominal strain occurs.
Since the occurrence of abdominal distortion tends to be less likely to occur than ear distortion, in the present invention, priority is given to preventing the occurrence of ear distortion, and it is preferable to finish the thickness of the inner side of the board slightly thicker than the edge of the board. . Specifically, in order to make the plate thickness of the ear portion with respect to the average plate thickness of the plate constant or less, it is preferable to set the a value defined as follows to 1.0 or less.
a = h / c
h: Difference between the thickness of the ear plate and the minimum plate thickness c: Difference between the maximum plate thickness of the central portion and the minimum plate thickness In addition, since the plate thickness inside the plate is not too thick relative to the average plate thickness, The pc value defined as above is preferably set to 2.0% or less.
pc = c / tc × 100 (%)
c: Difference between the maximum plate thickness at the center and the minimum plate thickness tc: maximum plate thickness at the center These values can be understood more easily by referring to FIG. 2 of JP-A-11-254847. .
Moreover, in the cold rolling process mentioned later, a value and pc value can be adjusted to a desired value by adjusting the bending shape of a cold rolling roll.

  The aluminum alloy plate preferably has a bend of 4 mm or less of 0.3 mm or less. When the bend of the aluminum alloy plate is large, when it is wound as a coil, the winding shift gradually increases as it is wound, and the end of the plate due to the winding shift or distortion occurs. The target value of the bend can be achieved by controlling the parallelism of the cold rolling roll and the feeding accuracy of the aluminum plate in the cold rolling mill. In the present invention, the burr height at the end of the plate is preferably 10 μm or less. For the same reason as described in the description of the cross-sectional shape, if the burr at the end is large, plastic deformation at the end tends to occur while being wound and stored as a coil. In addition, in the surface treatment for obtaining a lithographic printing plate support and the image recording layer coating step for obtaining a lithographic printing plate precursor, burrs tend to damage the lithographic printing plate precursor production equipment such as a pass roll and a coating device. Therefore, it is not preferable. Therefore, as described above, the height of the burr is preferably 10 μm or less. The burr height can be reduced to 10 μm or less by controlling the clearance of the blade in the slitter process for cutting off the coil ears. In addition, a slitter line is usually used for processing to a predetermined plate width. At the end face of the plate cut by the slitter, when the slitter blade cuts, one or both of a shear plane and a fracture surface are generated.

The plate thickness of the aluminum plate is preferably in the range of 0.10 to 0.50 mm, and the accuracy is that the plate thickness difference over the entire length of the coil is preferably within 20 μm, and within 12 μm. More preferred. The plate thickness difference in the width direction is preferably 6 μm or less, and more preferably 3 μm or less. The plate width accuracy is preferably within 2.0 mm, more preferably within 1.0 mm.
As a printing plate for newspaper, a plate having a thickness of 0.285 to 0.315 mm is usually used.

  The above aluminum alloy sheet is formed by ingot-making an aluminum alloy ingot having the above-described composition by continuous casting or DC casting, and the obtained ingot is homogenized and then hot rolled / cold rolled. Can be manufactured. Here, in the hot rolling process comprising hot rough rolling and hot finish rolling, the rolling start temperature in hot rough rolling, the rolling end temperature, the holding time until the transition from rough rolling to finish rolling, hot finish rolling By specifying the end temperature and controlling the recrystallized grains after coiling as a coil after hot finish rolling, after hot finish rolling, only the cold rolling without intermediate annealing is performed to a predetermined thickness It is preferable to use a plate material.

  First, after chamfering the rolled surface layer of the ingot of the aluminum alloy having the above-described composition to remove the non-uniform structure that causes streak, it is at least 1 hour in the temperature range of 500 to 600 ° C. It is preferable to perform the homogenization treatment. By this homogenization treatment, Fe and Si dissolved in supersaturation are uniformly deposited, and the etching pits formed during the electrolytic treatment become fine circles, and the printing durability is improved. When the homogenization temperature is less than 500 ° C., the precipitation of Fe and Si is not sufficient, and the pit pattern tends to be non-uniform. When the homogenization treatment is performed at a temperature exceeding 610 ° C., the amount of Fe dissolved increases, resulting in a decrease in fine precipitates that are the starting point of pit generation. If the holding time of the homogenization treatment is less than 1 hr, the precipitation of Fe and Si is insufficient and the pit pattern tends to be non-uniform.

  Hot rolling is usually performed in a hot rolling line after performing hot rough rolling in a rough rolling stand, then transferring the rolled material to a finishing rolling stand, performing hot finish rolling in the finishing rolling stand, In the present invention, hot rough rolling starts at 400 to 520 ° C., ends at a temperature of 400 ° C. or higher, and finishes after hot rough rolling. It is preferable to recrystallize the surface of the hot rough rolled material by holding the hot rough rolled material for 60 to 300 seconds before starting the hot finish rolling. Thereby, the density | concentration of Mg in the surface layer part mentioned above can be obtained. That is, the Mg concentration in the surface layer portion from the aluminum alloy plate surface to a depth of 0 to 2 μm can be adjusted to 5 to 50 times the average Mg.

If the start temperature of hot rough rolling is less than 400 ° C., the deformation resistance of the material is large, and the number of rolling passes may increase, which may reduce productivity. When the temperature exceeds 520 ° C., coarse recrystallized grains are generated during rolling, and a streak-like non-uniform structure tends to be formed.
When the end temperature of hot rough rolling is less than 400 ° C., recrystallization due to holding after the end of hot rough rolling becomes insufficient, and it becomes difficult to obtain a uniform surface layer structure, and it is difficult to obtain the Mg concentration in the surface layer portion described above. Become.
In addition, when the holding time after the hot rough rolling is finished and before the hot finish rolling is started is less than 60 seconds, recrystallization becomes insufficient and it becomes difficult to obtain a uniform surface structure. If the time is maintained for more than 300 seconds, the recrystallized grains grow and partially coarse recrystallized grains are generated, and it is difficult to obtain fine recrystallized grains at the end of hot rolling.

Next, it is preferable to perform hot finish rolling and finish the hot finish rolling at a temperature of 330 ° C. or higher and wind it up as a coil. When the finish temperature of hot finish rolling is less than 330 ° C., recrystallization occurs only partially, which may cause streaks.
The finish temperature of hot finish rolling is preferably 370 ° C. or lower. When the finish temperature of hot finish rolling exceeds 370 ° C., the recrystallized grains become coarse and a stroke is likely to occur.

  After performing the above hot rolling, by winding up as a coil, the average recrystallized grain size in the direction perpendicular to the rolling method of the surface layer portion of the hot finish rolled material can be reduced to 50 μm or less. After finish rolling, it becomes possible to make a plate material of a predetermined thickness only by cold rolling without performing intermediate annealing, and it is possible to improve productivity and accordingly reduce manufacturing cost, after each cold rolling In the final rolled material, the average recrystallized grain size in the direction orthogonal to the rolling direction of the rolled material of the surface layer portion can be set to 50 μm or less to prevent surface unevenness due to aluminum crystals on the printing plate.

Moreover, in the final rolled material after cold rolling, by obtaining an average surface roughness Ra in the direction perpendicular to the rolling direction of the surface of 0.03 to 0.5 μm, an effect of improving ink stain resistance can be obtained. Can do. When Ra is less than 0.03 μm, when applied as a printing plate, the amount of dampening water retained may be drastically reduced, and the ink in the image area easily moves onto the non-image area, resulting in ink stain resistance. descend. If Ra exceeds 0.5 μm, the planket cylinder may become dirty. In order to improve the ink stain resistance, it is necessary to have an average surface roughness Ra capable of maintaining a sufficient water retention amount. For this reason, the arithmetic average roughness of the roughened finished surface is 0.03. It is preferable to set it as the range of -0.5 micrometer, and it is more preferable to set it as 0.10-0.40 micrometer.
In order to set the arithmetic average surface roughness Ra in the direction orthogonal to the rolling direction of the plate surface to 0.03 to 0.5 μm, the outer diameter is 250 to 700 mm and Ra in the direction orthogonal to the rolling direction is 0.03 to 0.03. It is necessary to perform final cold rolling using a 0.6 μm work roll (WR) and adjust the final cold work degree, rolling speed, rolling oil properties, and rolling oil supply amount according to the alloy composition. It is.

In the present invention, the amount of aluminum powder on the surface of the rolled sheet after final cold rolling is preferably adjusted to 0.1 to 3.0 mg / m ² . The aluminum powder is an aluminum alloy powder remaining on the rolled plate surface generated from the aluminum alloy rolled material during the final cold rolling. In the case of an aluminum alloy containing Mg, the amount of aluminum powder is 0.00. If it is less than 1 mg / mm ² , the effect of preventing scratches in the coil may not be sufficient when wound as a coil after the final cold rolling. If it exceeds 3.0 mg / m ² , the aluminum powder is not sufficiently removed in the degreasing process and remains on the plate surface, and pit formation is insufficient or incomplete in the portion where the aluminum powder remains during the electrolytic surface roughening treatment. It becomes uniform and causes an appearance defect due to an unetched portion or uneven pattern after electrolytic surface roughening. Excessive aluminum powder can also cause line contamination.
In order to adjust the amount of aluminum powder on the surface of the aluminum alloy plate after the final cold rolling to the above range, in addition to the adjustment to the above components, the final cold rolling degree of processing, the properties of the rolling oil, the rolling oil according to the composition It is necessary to adjust the supply amount. In particular, the viscosity of the rolling oil in the final cold rolling is important, and it is preferable to use a rolling oil having a viscosity of 1 to 6 cSt. When the viscosity is less than 1 cSt, the amount of rolling oil introduced between the rolling roll and the rolled material is reduced, resulting in lubrication failure and excessive aluminum powder is likely to occur. When the viscosity exceeds 6.0 cSt, the amount of rolling oil introduced between the rolling roll and the rolled material becomes excessive, and the generation of aluminum powder tends to be reduced. The amount of aluminum powder is determined by quantifying the residual wear powder on the surface of the aluminum alloy plate by wiping with a cotton wool soaked with a certain surface performance on the surface of the plate and measuring the aluminum content in the cotton wool. Can be measured.

  As the rolling oil in the final cold rolling, the relationship between the Mg content (Mg%) in the aluminum alloy and the viscosity ρ of the rolling oil used in the final cold rolling satisfies ρ ≦ 2 × Mg% + 4. It is preferable to use rolling oil. When ρ> (2 × Mg% + 4), the deformation resistance is small, and the amount of rolling oil introduced between the rolling roll and the rolled material increases, so that coarse pits called oil pits are excessive in the rolling process. It becomes easy to be formed.

In the present invention, by adjusting the number of oil pits having a diameter (equivalent circle diameter) of 30 μm or more to 50 pieces / mm ² or less on the surface of the aluminum alloy plate after the final cold rolling, The formed etching pits can be made more uniform.
When the aluminum alloy plate contains Mg, large oil pits having a diameter of 30 μm or more are likely to remain as coarse pits even after roughening, and if such coarse pits exceed 50 / mm ² , The surface after conversion tends to be non-uniform.

In order to adjust the number of oil pits having a diameter (equivalent circle diameter) of 30 μm or more to 50 / mm ² or less, the final cold rolling degree, the form of the rolling roll surface, the properties of the rolling oil, the supply of the rolling oil It is necessary to adjust the amount. In the case of an aluminum alloy sheet containing Mg and having a relatively large deformation resistance, a roll having a roll surface roughness of arithmetic average roughness Ra = 0.2 to 0.5 μm is used in the final cold rolling, and the viscosity is 1 It is desirable to perform cold rolling using a rolling oil of 0.0 to 6.0 cSt.
If the roll surface roughness exceeds 0.5 μm in terms of arithmetic average roughness Ra, the local surface pressure within the contact arc length increases, and the oil film is cut and the metal contact area increases. Become. When Ra is less than 0.2 μm, the amount of rolling oil introduced between the rolling roll and the rolled material becomes excessive, and the number of large oil pits increases. If the viscosity of the rolling oil is less than 1.0 cSt, the amount of rolling oil introduced between the rolling roll and the rolled material tends to be small and lubrication failure tends to occur. If the rolling oil exceeds 6.0 cSt, The amount of rolling oil introduced between them becomes excessive, and the number of large oil pits increases. For oil pits, after degreasing and cleaning the surface of the aluminum alloy plate, the surface is observed at a magnification of 500 times using a scanning electron microscope (SEM), and the number and distribution of oil pits are measured by a cutting method. can do.

  The aluminum alloy sheet has a uniform degree of recrystallization at the surface layer portion, fine recrystallized grains, and uniform at the stage of winding as a coil after hot finish rolling, and intermediate annealing after hot rolling. Can be cold-rolled to the final thickness without performing the process, and an appropriate Mg concentration can be obtained in the surface layer of the plate, and the generation of pits during the electrochemical etching process is uniform and fine, and the roughening process is performed. When carried out, an aluminum support for a lithographic printing plate is provided which does not generate any streaking and has excellent strength characteristics.

The aluminum alloy plate finished to a predetermined thickness of 0.10 to 0.50 mm by cold rolling may be further improved in flatness by a correction device such as a roller leveler or a tension leveler.
In addition, a slitter line is usually used for processing to a predetermined plate width.

Methods for increasing the strength (tensile strength, 0.2% yield strength) of aluminum alloy sheets include solid solution strengthening (method depending on additives), work hardening (method for increasing the cold rolling reduction ratio), precipitation hardening, and crystal structure. Although there is hardening by miniaturization, in the present invention, a method of solid solution strengthening is preferred, and a method of using both solid solution strengthening and work hardening is most preferred.
Mn, Mg, Fe, Cu and the like are known as alloy components that increase the strength (tensile strength, 0.2% proof stress) of the aluminum alloy plate, but 0.05 to 0.40% Mg or Mn A method of adding 0.05 to 1.50% is preferable, and a method of adding Mg is more preferable. When Mn is added, the strength (tensile strength, 0.2% proof stress) of the aluminum alloy sheet increases, but the alkaline etching solution used for the roughening treatment is contaminated black by Mn, and the contaminant (Mn) is contaminated with the aluminum alloy sheet. Reattached to the product may cause a failure.
As a particularly preferable method, Mg is added in an amount of 0.05% or more and less than 0.10%, and the work hardening by increasing the rolling reduction of the cold rolling is used in combination, so that the rolling direction of the surface layer portion of the aluminum alloy sheet is increased. The average recrystallized grain size in the direction perpendicular to the diameter is 0.01 to 0.05 mm, and the crystal length stretched in the rolling direction is 0.50 to 0.90 mm on average.

[Preparation of aluminum support for lithographic printing plate]
The aluminum support for a lithographic printing plate of the present invention can be obtained by roughening the surface of the aluminum alloy plate by a known method such as electrical graining and further anodizing.
Here, the surface area ratio (also referred to as the specific surface area) ΔS calculated by the following formula (I) from the actual area of the aluminum support measured by using an atomic force microscope and measured by three-dimensional data is the adhesion of the image recording layer. From the viewpoint of property, it is required to be 45% or more, particularly preferably 50% or more.
Further, ΔS is preferably 70% or less, and particularly preferably 60% or less. When ΔS exceeds 70%, the steepness of the surface becomes high, and the antifouling performance may be lowered. Here, ΔS is a value calculated from the following formula (I) from three-dimensional data obtained by measuring 256 × 256 points with a 25 μm square using an atomic force microscope.
ΔS = (surface area obtained by approximate three-point method−geometric area)
/ Geometric area x 100 (%) Formula (I)
ΔS is a factor indicating the degree of increase in the actual area due to the roughening treatment with respect to the geometric measurement area. When ΔS increases, the contact area with the image recording layer increases, and as a result, printing durability can be improved. By setting the surface area ratio within a predetermined range, it is possible to improve the printing durability by taking a sufficient contact area between the image recording layer and the aluminum support.
In order to achieve such a range of ΔS, for example, electrochemical roughening using an alternating current in an aqueous solution mainly composed of hydrochloric acid or nitric acid, mechanical roughening using a brush roll and an abrasive. A known method such as a surface treatment method or a chemical etching method may be applied, and the treatment may be performed under conditions capable of forming the surface irregularities.

  The whiteness of the aluminum support surface is preferably 0.30 to 0.55, particularly preferably 0.35 to 0.50. If it is less than 0.30, the printing durability deteriorates, and if it exceeds 0.55, the stain resistance decreases.

In the present invention, two-dimensional roughness measurement is performed on the aluminum support surface with a stylus type roughness meter (for example, sufcom 575, manufactured by Tokyo Seimitsu Co., Ltd.), and the average surface roughness Ra specified in ISO 4287 is 5 The average value is taken as the average surface roughness Ra. The conditions for the two-dimensional roughness measurement are shown below.
<Measurement conditions>
Cut-off value 0.8mm, tilt correction FLAT-ML, measurement length 3mm, vertical magnification 10000 times, scanning speed 0.3mm / sec, stylus tip diameter 2μm

A particularly preferred roughening treatment method for bringing the surface property of the aluminum support into the above preferred range will be described below.
Specifically, the aluminum alloy plates in order
(1) Electrochemical roughening treatment using alternating current in an acidic aqueous solution (first electrolytic roughening treatment)
(2) An electrochemical surface roughening treatment using alternating current in an acidic aqueous solution (second electrolytic surface roughening treatment),
(3) Anodizing treatment (anodizing treatment)
Is preferred.
Most preferably, the aluminum alloy plates in order
(1) Mechanically roughening (mechanical roughening)
(2) Chemically etching in an alkaline aqueous solution (first etching process),
(3) Electrochemical roughening treatment using alternating current in an aqueous nitric acid solution (first electrolytic roughening treatment)
(4) Chemically etching in an alkaline aqueous solution (second etching process)
(5) Electrochemical roughening treatment using alternating current in aqueous hydrochloric acid (second electrolytic roughening treatment)
(6) Chemically etching in an aqueous alkali solution (third alkali etching process)
(7) Anodizing treatment (anodizing treatment)
It is a method to do.
It is more preferable to perform desmut treatment (first desmut treatment, second desmut treatment, third desmut treatment) in an acidic aqueous solution after the chemical etching treatment in the alkaline aqueous solution.
Moreover, after the anodizing treatment, a hydrophilization treatment is performed as necessary soaking in a sodium silicate aqueous solution.

Hereinafter, a preferable roughening treatment method will be described.
<Mechanical roughening>
In the present invention, the average surface roughness Ra of the aluminum alloy plate described above is 0.35 to 0.65 μm, preferably 0.40 to 0.60 μm, using a brush and a slurry liquid containing an abrasive. It is preferable to perform a mechanical surface roughening treatment that mechanically roughens the surface.
The mechanical roughening treatment is a method of brush polishing using one or two or more brushes having different bristle diameters while supplying a slurry liquid containing an abrasive to the aluminum alloy plate surface (brush grain method) Specifically, a wire brush grain method in which the surface of the aluminum alloy plate is scratched with a metal wire, a brush grain method in which the surface of the aluminum alloy plate is grained using a nylon brush, and the like are preferably exemplified.

In addition, the brush grain method generally uses synthetic resin hair made of synthetic resin such as nylon (registered trademark), polypropylene, and vinyl chloride resin on the surface of a cylindrical body, or brush hair (animal hair, steel wire, etc.) Roller brushes (brushes) such as those in which a material is planted on a roller-shaped base with uniform hair length and flocking distribution, small holes are drilled in the base and brush bundles are implanted, and channel roller type Roll), and by rubbing one or both of the surfaces of the aluminum alloy plate described above while spraying a slurry liquid containing an abrasive on a rotating roller brush.
Flexural modulus of the brush bristles is preferably from 10,000~40,000kgf / cm ^2, and more preferably 15,000~35,000kgf / cm ^2. The strength of the bristle of the brush hair is preferably 500 gf or less, and more preferably 400 gf or less.

Nylon is preferable as the material of the bristle sufficiently satisfying such characteristics. Specifically, nylon 6, nylon 6,6, nylon 6,10, and the like can be used. Among them, it is particularly preferable to use nylon 6 · 10 from the viewpoints of tensile strength, abrasion resistance, dimensional stability due to water absorption, bending strength, heat resistance, recoverability, and the like.
Such a nylon brush preferably has a low water absorption rate. Specific examples thereof include nylon bristle 200T (nylon 6 · 10, softening point: 180 ° C., melting point: 212 to 214 ° C., specific gravity, manufactured by Toray Industries, Inc. : 1.08 to 1.09, moisture content: 1.4 to 1.8 at 20 ° C and relative humidity 65%, 2.2 to 2.8 at 20 ° C and relative humidity 100%, dry tensile strength: 4. 5-6 g / d, dry tensile elongation: 20-35%, boiling water shrinkage: 1-4%, dry tensile resistance: 39-45 g / d, Young's modulus (dry): 380-440 kg / mm ² ) Are preferable.

Moreover, it is preferable that the hair length after the flocking of a brush hair is 10-200 mm. In addition, it is preferable that the flocking density at the time of planting in a roller base part is 30-1000 per cm < ² >, and it is more preferable that it is 50-300.

In order to obtain a rough surface having an average surface roughness Ra of 0.35 to 0.65 μm using a brush and a slurry liquid containing an abrasive, the bristle diameter is 0.24 to 0.00 mm. 83 mm is preferable, and 0.26 to 0.50 mm is particularly preferable. If the bristle diameter is within this range, the desired average surface roughness is obtained, and the stain resistance on the blanket is also good.
The cross-sectional shape of the brush hair is preferably circular.

The number of brushes is preferably 1 to 10, and more preferably 3 to 6.
Furthermore, it is more preferable to use two types of brushes having different bristle diameters. At that time, first create a rough surface with a large average pitch using a brush with a thick bristle diameter, and then use a brush with a narrower hair diameter than the first brush to smooth out the sharp portions of uneven surface irregularities. It is particularly preferred.

When a roller brush is used as the brush, the number of rotations of the brush is preferably selected arbitrarily in the range of 100 to 500 rpm.
The rotation direction of the roller brush is preferably forward rotation in the conveying direction of the aluminum alloy plate. However, when there are a large number of roller brushes, some roller brushes may be reversed.

The polishing slurry liquid is a known polishing agent described in JP-A-6-135175 and JP-B-50-40047, specifically, pumiston, silica sand, aluminum hydroxide, alumina powder, silicon carbide, silicon nitride. An abrasive having an average particle diameter of 1 to 100 μm (preferably 15 to 45 μm) such as volcanic ash, pumice, carborundum, and gold sand is dispersed in water so as to have a specific gravity of 1.05 to 1.3. preferable.
The polishing slurry liquid may contain a thickener, a dispersant (for example, a surfactant), a preservative, and the like in addition to the abrasive.

It is preferable to use pumiston because it is inexpensive and is used as an industrial abrasive, so that the supply is stable.
As the pumiston, it is preferable to use one containing the following components.
<Pamiston component>
Silica (silicic acid content: SiO ₂ ) 70-80% by mass
Alumina (Al ₂ O ₃ ) 10-20% by mass
Iron oxide (Fe ₂ O ₃ ) 3% by mass or less Other remaining

  As a method for supplying such a polishing slurry liquid to the surface of the aluminum alloy plate, for example, a method of spraying the slurry liquid is preferably exemplified. Moreover, you may use the method described in Unexamined-Japanese-Patent No. 55-74898, 61-162351, and 63-104889. Furthermore, as described in JP-A-9-509108, an aluminum alloy in an aqueous slurry containing a mixture of particles made of alumina and quartz at a mass ratio in the range of 95: 5 to 5:95. A method of brush polishing the surface of the plate can also be used. The average particle size of the mixture at this time is preferably in the range of 1 to 100 μm, particularly 15 to 45 μm.

  In the present invention, the number of rotations of the brush, the number of brushes, the direction of rotation of the brush, the bristle diameter of the brush, the bristle length of the brush, the diameter of the roller (brush roller) for planting the brush, the type of abrasive, the granularity of the abrasive, By appropriately adjusting conditions such as the specific gravity of the abrasive, the flow rate of the abrasive, the pressing force of the brush (pushing amount), and the moving speed of the aluminum plate, the average surface roughness Ra of the aluminum plate after the mechanical surface roughening treatment Can be set to 0.35 to 0.65 μm.

<First etching process>
A 1st etching process is a process which melt | dissolves the surface layer of an aluminum alloy plate by making the aluminum alloy plate in which the mechanical surface roughening process mentioned above was made to contact alkali solution.
In the present invention, the first etching treatment is preferably performed on the aluminum alloy plate subjected to the mechanical roughening. When the first etching process is performed after the mechanical surface roughening process, the abrasive, aluminum scrap, rolling oil, dirt, natural oxide film, etc. generated on the surface of the aluminum alloy plate by the mechanical surface roughening process Therefore, uniform unevenness is formed on the surface by the first electrolytic surface roughening treatment, and the first electrolytic surface roughening treatment can be effectively achieved.
In the first etching treatment, the etching amount is preferably at 0.5 g / m ² or more, more preferably 2 g / m ² or more, more preferably at 3 g / m ² or more, It is preferably 20 g / m ² or less, more preferably 15 g / m ² or less, and even more preferably 11 g / m ² or less. If the etching amount is too small, uniform pits cannot be generated in the first electrolytic surface roughening process, and unevenness may occur. On the other hand, when the etching amount is too large, printing durability and cleaner resistance are deteriorated. Moreover, when there are too many etching amounts, the usage-amount of alkaline aqueous solution will increase and it will become economically disadvantageous.

  Examples of the alkali used in the alkaline solution include caustic alkali and alkali metal salts. Specifically, examples of caustic alkali include caustic soda and caustic potash. Examples of the alkali metal salt include alkali metal silicates such as sodium metasilicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium aluminate and alumina. Alkali metal aluminates such as potassium acid; Alkali metal aldonates such as sodium gluconate and potassium gluconate; secondary sodium phosphate, secondary potassium phosphate, tertiary sodium phosphate, tertiary potassium phosphate, etc. An alkali metal hydrogen phosphate is mentioned. Among these, a caustic alkali solution and a solution containing both a caustic alkali and an alkali metal aluminate are preferable from the viewpoint of high etching rate and low cost. In particular, an aqueous solution of caustic soda is preferable.

In the first etching treatment, the concentration of the alkaline solution is preferably 30 g / L or more, more preferably 300 g / L or more, and preferably 500 g / L or less, 450 g / L or less. It is more preferable that
The alkaline solution preferably contains aluminum ions. The aluminum ion concentration is preferably 1 g / L or more, more preferably 50 g / L or more, and preferably 200 g / L or less, more preferably 150 g / L or less. Such an alkaline solution can be prepared using, for example, water, a 48 mass% sodium hydroxide aqueous solution, and sodium aluminate.

  In the first etching treatment, the temperature of the alkaline solution is preferably 30 ° C or higher, more preferably 50 ° C or higher, and preferably 80 ° C or lower, and 75 ° C or lower. More preferred.

  In the first etching treatment, the treatment time is preferably 1 second or longer, more preferably 2 seconds or longer, more preferably 30 seconds or shorter, and more preferably 15 seconds or shorter. .

Examples of the method of bringing the aluminum plate into contact with an alkaline solution include, for example, a method of passing an aluminum alloy plate through a bath containing an alkaline solution, a method of immersing an aluminum alloy plate in a bath containing an alkaline solution, and an alkaline solution. Can be sprayed onto the surface of the aluminum alloy plate.
After the alkali etching treatment is completed, it is preferable to drain the liquid with a nip roller, and further perform the water washing treatment for 1 to 10 seconds and then drain the liquid with a nip roller.

<First desmut treatment>
After the first etching process, it is preferable to perform pickling (first desmut process) in order to remove dirt (smut) remaining on the surface. The desmut treatment is performed by bringing the aluminum alloy plate into contact with an acidic solution.
Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid.
In the first desmut process performed after the first etching process, it is preferable to use the overflow waste liquid of the electrolyte used in the subsequent first electrolytic surface roughening process.
In the composition management of the desmut treatment liquid, a method of managing by electrical conductivity and temperature, a method of managing by electrical conductivity, specific gravity and temperature, and an electrical conductivity and superconductivity corresponding to the matrix of acidic solution concentration and aluminum ion concentration. Either of the methods managed by the propagation speed of sound waves and temperature can be selected and used.

  In the first desmutting treatment, it is preferable to use an acidic solution containing 1 to 400 g / L acid and 0.1 to 5 g / L aluminum ions. More preferably, nitric acid having a concentration of 10 to 100 g / L and a liquid temperature of 20 to 60 ° C. is used, and nitric acid having a concentration of 12 to 20 g / L and 30 to 50 ° C. is particularly preferable. Industrially, it is particularly preferable to use the overflow waste liquid of the first electrochemical surface roughening.

  The temperature of the acidic solution is preferably 20 ° C. or more, more preferably 30 ° C. or more, and preferably 70 ° C. or less, more preferably 60 ° C. or less.

  In the first desmutting treatment, the treatment time is preferably 1 second or longer, more preferably 2 seconds or longer, and preferably 60 seconds or shorter, more preferably 10 seconds or shorter. .

Examples of the method of bringing an aluminum alloy plate into contact with an acidic solution include a method of passing an aluminum alloy plate through a tank containing an acidic solution, a method of immersing an aluminum alloy plate in a tank containing an acidic solution, and an acidic solution. The method of spraying a solution on the surface of an aluminum alloy plate is mentioned.
After the desmutting process is completed, it is preferable to drain the liquid with a nip roller, and further perform the water washing process for 1 to 10 seconds, and then drain the liquid with a nip roller.
In the first desmut process, when the overflow waste liquid of the electrolyte used in the subsequent first electrolytic surface-roughening process is used as the desmut process liquid, the draining and rinsing processes by the nip roller are not performed after the desmut process. In order to prevent the surface of the aluminum alloy plate from drying, it is preferable to handle the aluminum plate up to the first electrolytic surface-roughening treatment step while spraying a desmut treatment liquid as necessary.

<First electrolytic surface roughening treatment>
The first electrolytic surface roughening treatment is performed to produce honeycomb pits having an average diameter of 0.5 to 5 μm on the surface of the aluminum alloy plate, and to obtain a support that satisfies the printing durability and stain resistance.
In the present invention, the first electrolytic surface roughening treatment is performed in an aqueous solution containing nitric acid at 5.0 to 15.0 g / L and aluminum ions at 3.0 to 8.0 g / L and having a liquid temperature of 30 to 60 ° C. The electrochemical surface-roughening process which roughens using AC current.
The aluminum ion concentration can be adjusted by adding, for example, aluminum nitrate (9 hydrate).

  The waveform of the alternating current used for the first electrolytic surface roughening treatment is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, or the like is used. A sine wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable. . In this trapezoidal wave, the time (TP) until the current reaches a peak from zero is preferably 0.5 to 3 msec. When TP exceeds 3 msec, especially when an aqueous solution containing nitric acid is used, it becomes susceptible to the influence of trace components in the electrolytic solution typified by ammonium ions and the like that spontaneously increase by electrolytic treatment, and uniform graining. Is difficult to be performed. As a result, the stain resistance tends to decrease when a lithographic printing plate is obtained.

The current density in the first electrolytic surface roughening treatment is preferably 10 to 300 A / dm ² , more preferably 15 to 200 A / dm ² in terms of the average current density in the main electrolytic layer, and 20 to 125 A / dm ^2. more preferably in the range of dm ^2. In the case of the above range, the productivity is more excellent, the voltage is not increased, and the power supply capacity is not too large, so that the power supply cost can be reduced.
The average current density referred to in the present invention is obtained by dividing the total amount of electricity left for the anodic reaction of the aluminum plate by the electrolytic treatment time and the treatment area by the alternating current flowing between the aluminum alloy plate facing the main electrode and the main electrode. Say.

The trapezoidal wave duty that can be used is preferably 0.33 to 0.67. The duty is a value obtained by dividing the time during which the aluminum alloy plate is anodic in one cycle by the time of one cycle.
Moreover, although the frequency of the trapezoidal wave that can be used is preferably 0.1 to 120 Hz, it is more preferable to use an alternating current of 50 to 70 Hz in terms of equipment.

  As the electrolytic cell, electrolytic cells used for known surface treatments such as a vertical type, a flat type, and a radial type can be used, but a radial type electrolytic cell as described in JP-A-5-195300 is particularly preferable. . The electrolytic solution passing through the electrolytic cell may be parallel to the traveling direction of the aluminum web or may be a counter.

By the first electrolytic surface roughening treatment, pits having an average opening diameter of 0.5 to 5 μm can be formed.
To obtain such a grain, the total quantity of electricity when the anode of the aluminum alloy plate up until the electrolysis reaction is completed, that is 50~300C / dm ² preferably 100~250C / dm ² More preferably.
After the first electrolytic surface roughening treatment is completed, it is preferable to drain the liquid with a nip roller, and further perform the water washing treatment for 1 to 10 seconds and then drain the liquid with a nip roller.

  Moreover, as a power supply device, what used commercial alternating current, an inverter control power supply, etc. can be used, for example. Among them, an inverter control power source using an IGBT (Insulated Gate Bipolar Transistor) element can generate an arbitrary waveform by PWM (Pulse Width Modulation) control, the width and thickness of an aluminum alloy plate, and the concentration of each component in the electrolyte When the voltage is changed with respect to the fluctuation of the current and the current value (current density of the aluminum plate) is controlled to be constant, it is preferable in terms of excellent followability.

Further, as the first electrolytic surface roughening treatment, electrolytic surface roughening using alternating current in a hydrochloric acid aqueous solution can be used. At this time, it is possible to omit the mechanical roughening process.
As the first electrolytic surface roughening treatment, preferred ranges when using electrolytic surface roughening using alternating current in aqueous hydrochloric acid are shown below.
The concentration of hydrochloric acid in the electrolytic solution is 5.0 to 20.0 g / L, and preferably 10.0 to 18.0 g / L.
Moreover, the aluminum ion density | concentration of electrolyte solution is 5.0-20.0 g / L, and it is preferable that it is 10.0-18.0 g / L. The aluminum ion concentration can be adjusted by adding aluminum chloride, for example.
Further, it is preferable to electrochemically roughen the surface using an alternating current using an electrolytic solution in which 1 to 10 g / l, particularly 1 to 5 g / l of sulfuric acid is added to the aqueous solution mainly containing hydrochloric acid. By adding sulfuric acid, crater-like pits can be generated more uniformly.

  Further, the electrolytic solution can be used by adding at least one of chlorine compounds having hydrochloric acid ions such as aluminum chloride, sodium chloride and ammonium chloride in a range from 1 g / L to saturation. Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in electrolyte solution.

  The liquid temperature of the electrolytic solution is preferably 25 to 45 ° C, more preferably 30 to 40 ° C.

The waveform of the alternating current used for the electrolytic surface roughening treatment is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, or the like is used, and a sine wave is particularly preferable.
The current waveform applied to the aluminum alloy plate is preferably symmetric between positive and negative.
The current density in the electrolytic surface roughening treatment is preferably from 10~400A / dm ² at the peak current value of the alternating current waveform, more preferably from 15~350A / dm ^2, in 20~300A / dm ² More preferably.
Moreover, although the alternating current frequency which can be used for electrochemical roughening is preferably 0.1 to 120 Hz, it is more preferable to use an alternating current of 40 to 70 Hz.
The amount of electricity is preferably 250 to 800 C / dm ² , more preferably 300 to 600 C / dm ^{2 in} terms of the total amount of electricity left for the anodic reaction of the aluminum plate.

As the electrolytic cell, an electrolytic cell used for a known surface treatment such as a known vertical type, flat type or radial type in which a plurality of electrodes are arranged in the electrolytic cell can be used. The electrolytic solution passing through the electrolytic cell may be parallel to the traveling direction of the aluminum web or may be a counter.
It is preferable to use 1 to 10 electrolytic cells arranged in series in the traveling direction of the aluminum alloy plate, and it is particularly preferable to use 2 to 6 electrolytic cells. Based on an arbitrary point on the aluminum alloy plate in the traveling direction of the moving aluminum alloy plate, the interval between the plurality of electrodes installed in the electrolytic cell is preferably 0.001 to 0.5 seconds. The interval between the plurality of electrolyzers and electrolyzers is preferably 1 second to 10 seconds. The quantity of electricity applied to the aluminum plate from one per electrode is preferably 1 to 10C / dm ^2. When using a plurality of electrolytic cells, the quantity of electricity applied to the per electrolytic cell 1 cell is more preferably 80~200C / dm ^2.

<Second etching process>
The second etching treatment is a chemical etching treatment for dissolving the surface layer of the aluminum alloy plate by bringing the aluminum alloy plate subjected to the first electrolytic surface roughening treatment into contact with an alkali solution or an acid solution. It is preferably an alkali etching treatment using an alkaline solution that is similar to the etching treatment and has excellent dissolution efficiency.
In the second etching treatment, it is preferable that the dissolved amount of the aluminum alloy plate (etching amount) is 0.0.05~7.0g / m ^2, to be 0.1 to 0.6 g / m ² More preferred. If it is less than 0.05 g / m ² , the edge portion of the pit generated by the first electrolytic surface roughening treatment will not be smooth and the ink will be easily caught, so that sufficient anti-stain performance cannot be obtained, and 7.0 g If it exceeds / m ² , the unevenness generated by the first electrolytic surface roughening treatment becomes small, so that sufficient printing durability cannot be obtained.
In the second etching process, the smut generated in the first electrolytic surface roughening treatment is dissolved by bringing the aluminum alloy plate subjected to the first electrolytic surface roughening treatment into contact with an alkaline solution, and the first electrolysis surface treatment is performed. This is performed for the purpose of dissolving the edge portion of the pit formed by the roughening treatment. Since the second etching process is basically the same as the first etching process, only different points will be described below.

In the second etching treatment, the concentration of the alkaline solution is preferably 30 g / L or more, more preferably 300 g / L or more, and preferably 500 g / L or less, 450 g / L or less. It is more preferable that
The alkaline solution preferably contains aluminum ions. The aluminum ion concentration is preferably 1 g / L or more, more preferably 50 g / L or more, and preferably 200 g / L or less, more preferably 150 g / L or less. Such an alkaline solution can be prepared using, for example, water, a 48 mass% sodium hydroxide aqueous solution, and sodium aluminate.
In the second etching treatment, the temperature of the alkaline solution is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, preferably 60 ° C. or lower, and 50 ° C. or lower. More preferred.
In the second etching treatment, the treatment time is preferably 1 second or more, more preferably 2 seconds or more, and preferably 30 seconds or less, more preferably 10 seconds or less. .

<Second desmut treatment>
After the second etching process, it is preferable to perform pickling (second desmut process) in order to remove dirt (smut) remaining on the surface. Since the second desmut process is basically the same as the first desmut process, only the differences will be described below.
In the second desmut treatment, nitric acid or sulfuric acid is preferably used.
In the second desmut treatment, it is preferable to use an acidic solution containing 1 to 400 g / L of acid and 0.5 to 8 g / L of aluminum ions.
In the second desmut treatment, the treatment time is preferably 1 second or longer, more preferably 4 seconds or longer, and preferably 60 seconds or shorter, more preferably 20 seconds or shorter. .

<Second electrolytic surface roughening treatment>
After the second etching process is performed, it is preferable to perform a second electrolytic surface roughening process. The second electrolytic surface roughening treatment is an electrochemical surface roughening treatment using an alternating current in an aqueous solution containing hydrochloric acid (hereinafter referred to as “second electrolytic solution”). By performing the second electrolytic surface roughening treatment, an uneven structure having pits having an average opening diameter of 0.05 to 0.4 μm can be formed on the surface of the aluminum alloy plate. As a result, cleaner resistance is improved.
The second electrolytic surface roughening treatment can be performed in substantially the same manner as the first electrolytic surface roughening treatment described above except that the electrolytic solution is different. Only different points will be described below.

The second electrolytic solution is added to an aqueous solution of hydrochloric acid having a concentration of 1 to 100 g / L in a range from 1 g / L to saturation of at least one hydrochloric acid compound having hydrochloric acid ions such as aluminum chloride, sodium chloride, and ammonium chloride. Can be used. Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in the 2nd electrolyte solution.
Specifically, a solution prepared by dissolving aluminum chloride in an aqueous nitric acid solution having a hydrochloric acid concentration of 2 to 10 g / L to adjust the aluminum ion concentration to 3 to 7 g / L is preferable.
The temperature of the second electrolytic solution is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, preferably 55 ° C. or lower, and more preferably 40 ° C. or lower.

Since hydrochloric acid itself has a strong ability to dissolve aluminum, it is possible to form fine irregularities on the surface with only slight electrolysis. These fine irregularities have an average opening diameter of 0.01 to 0.2 μm and are uniformly generated on the entire surface of the aluminum plate. In order to obtain such a grain, the total amount of electricity involved in the anode reaction of the aluminum plate at the time when the electrolytic reaction is completed is preferably 10 C / dm ² or more, and is 50 C / dm ² or more. Is more preferably 100 C / dm ² or less, and more preferably 80 C / dm ² or less.

<Third alkali etching treatment>
It is preferable that a 3rd alkali etching process is performed after a 2nd electrolytic surface roughening process. In the third alkali etching treatment, the smut generated in the second electrolytic surface roughening treatment is dissolved by bringing the aluminum alloy plate subjected to the second electrolytic surface roughening treatment into contact with an alkaline solution, and second This is performed for the purpose of dissolving the edge portion of the pit formed by the electrolytic surface roughening treatment. Since the third alkali etching process is basically the same as the first etching process, only different points will be described below.
In the third alkali etching treatment, the etching amount is preferably at 0.01 g / m ² or more, more preferably 0.05 g / m ² or more, is 0.3 g / m ² or less Of 0.25 g / m ² or less is more preferable. If the etching amount is too small, the edge portion of the pit generated by the second electrolytic surface roughening process will not be smooth in the non-image area of the lithographic printing plate, and the ink will be easily caught, resulting in poor stain resistance. There is. On the other hand, if the etching amount is too large, the unevenness generated by the first electrolytic surface roughening treatment and the second electrolytic surface roughening treatment becomes small, so that the printing durability may deteriorate.

In the third alkali etching treatment, the concentration of the alkali solution is preferably 30 g / L or more, and in order not to make the unevenness caused by the second electrolytic surface roughening treatment in the previous stage too small, 100 g / L or less is preferable, and 70 g / L or less is more preferable.
The alkaline solution preferably contains aluminum ions. The aluminum ion concentration is preferably 1 g / L or more, more preferably 3 g / L or more, and preferably 50 g / L or less, more preferably 8 g / L or less. Such an alkaline solution can be prepared using, for example, water, a 48 mass% sodium hydroxide aqueous solution, and sodium aluminate.
In the third alkali etching treatment, the temperature of the alkaline solution is preferably 25 ° C or higher, more preferably 30 ° C or higher, and preferably 60 ° C or lower, and 50 ° C or lower. Is more preferable.
In the third alkali etching treatment, the treatment time is preferably 1 second or longer, more preferably 2 seconds or longer, more preferably 30 seconds or shorter, and more preferably 10 seconds or shorter. preferable.

<Third desmut processing>
After the third alkali etching treatment, pickling (third desmutting treatment) is preferably performed to remove dirt (smut) remaining on the surface. Since the third desmut process is basically the same as the first desmut process, only the differences will be described below.
In the third desmutting process, the same type of liquid as that used in the subsequent anodizing process (for example, sulfuric acid) is used, which eliminates the water washing step between the third desmutting process and the anodizing process. It is preferable in that it can be performed.
In the third desmutting treatment, it is preferable to use an acidic solution containing 5-400 g / L acid and 0.5-8 g / L aluminum ions.
In the third desmut treatment, the treatment time is preferably 1 second or more, more preferably 2 seconds or more, and preferably 60 seconds or less, more preferably 15 seconds or less. .
In the third desmut process, when the same type of liquid as the electrolyte used in the subsequent anodizing process is used as the desmut process liquid, the draining with a nip roller and the water washing process can be omitted after the desmut process.

<Anodizing treatment>
The aluminum alloy plate treated as described above is preferably further subjected to an anodizing treatment. The anodizing treatment can be performed by a method conventionally used in this field. In this case, for example, in a solution having a sulfuric acid concentration of 50 to 300 g / L and an aluminum concentration of 5% by mass or less, an anodized film can be formed by energizing an aluminum alloy plate as an anode. As a solution used for the anodizing treatment, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amidosulfonic acid and the like can be used alone or in combination of two or more.
Under the present circumstances, the component normally contained at least in an aluminum alloy plate, an electrode, tap water, groundwater, etc. may be contained in electrolyte solution. Furthermore, the 2nd, 3rd component may be added. Examples of the second and third components herein include metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn; Cations such as ammonium ion; anions such as nitrate ion, carbonate ion, chloride ion, phosphate ion, fluoride ion, sulfite ion, titanate ion, silicate ion, borate ion, etc., 0 to 10000 ppm It may be contained at a concentration of about.
The conditions for anodizing treatment vary depending on the electrolyte used, and thus cannot be determined unconditionally. In general, however, the electrolyte concentration is 1 to 80% by mass, the solution temperature is 5 to 70 ° C., and the current density is 0.5. ˜60 A / dm ² , voltage 1 to 100 V, and electrolysis time 15 seconds to 50 minutes are appropriate and adjusted so as to obtain a desired anodic oxide film amount.

Further, JP-A-54-81133, JP-A-57-47894, JP-A-57-51289, JP-A-57-51290, JP-A-57-54300, JP-A-57-136596, JP-A-58-107498, JP-A-60-200366, JP-A-62-136696, JP-A-63-176494, JP-A-4-17697, JP-A-4-280997, JP-A-6-280997 The methods described in JP-A-207299, JP-A-5-24377, JP-A-5-32083, JP-A-5-125597, JP-A-5-195291 and the like can also be used.
Of these, as described in JP-A-54-12853 and JP-A-48-45303, it is preferable to use a sulfuric acid solution as the electrolytic solution. The sulfuric acid concentration in the electrolytic solution is preferably 10 to 300 g / L (1 to 30% by mass), more preferably 50 to 200 g / L (5 to 20% by mass), and the aluminum ion concentration. Is preferably 1 to 25 g / L (0.1 to 2.5% by mass), more preferably 2 to 10 g / L (0.2 to 1% by mass). Such an electrolytic solution can be prepared, for example, by adding aluminum sulfate or the like to dilute sulfuric acid having a sulfuric acid concentration of 50 to 200 g / L.
The liquid temperature of the electrolytic solution is preferably 25 to 55 ° C, and more preferably 30 to 50 ° C.
When anodizing is performed in an electrolytic solution containing sulfuric acid, a direct current may be applied between the aluminum alloy plate and the counter electrode, or an alternating current may be applied.
When a direct current is applied to the aluminum alloy plate, the current density is preferably from 1 to 60 A / dm ^2, and more preferably 5 to 40 A / dm ^2.

In the case of continuous anodizing treatment, at the beginning of anodizing treatment, so that current is concentrated on a part of the aluminum alloy plate and so-called “burning” (part where the film becomes thicker than the surroundings) does not occur. It is preferable to increase the current density to 30 to 50 A / dm ² or higher as the anodic oxidation process proceeds with a current flowing at a low current density of 5 to 10 A / m ² .
Specifically, it is preferable that the current distribution of the DC power supply is set such that the current of the downstream DC power supply is equal to or greater than the current of the upstream DC power supply. By using such current distribution, so-called burning is less likely to occur, and as a result, high-speed anodization can be performed.
In the case where the anodic oxidation treatment is continuously performed, it is preferable to carry out by a liquid power feeding method in which power is supplied to the aluminum alloy plate through the electrolytic solution.

By performing anodizing treatment under such conditions, a porous film having many pores called micropores can be obtained. Usually, the average pore diameter is about 5 to 50 nm, and the average pore density is 300. it is a 800 pieces / μm ² about.
The amount of the anodized film is preferably located 1 to 5 g / m ^2. If it is less than 1 g / m ² , the plate tends to be damaged, whereas if it exceeds 5 g / m ² , a large amount of electric power is required for production, which is economically disadvantageous. The amount of the anodized film is more preferably 1.5 to 4 g / m ² . Moreover, it is preferable to carry out so that the difference in the amount of the anodized film between the center portion of the aluminum plate and the vicinity of the edge portion is 1 g / m ² or less.
As electrolysis apparatuses used for anodizing treatment, those described in JP-A-48-26638, JP-A-47-18739, JP-B-58-24517, JP-A-2001-11698, etc. Can be used.

<Sealing treatment>
In this invention, you may perform the sealing process which seals the micropore which exists in an anodic oxide film as needed. The sealing treatment can be performed according to a known method such as boiling water treatment, hot water treatment, steam treatment, sodium silicate treatment, nitrite treatment, ammonium acetate treatment and the like. For example, even if the sealing treatment is performed by the apparatus and method described in JP-B-56-12518, JP-A-4-4194, JP-A-5-20296, JP-A-5-179482, etc. Good.

<Hydrophilic treatment>
It is preferable to perform a hydrophilic treatment after the anodizing treatment or after the sealing treatment.
Examples of the hydrophilization treatment include treatment with potassium fluorozirconate described in US Pat. No. 2,946,638 and phosphomolybdate described in US Pat. No. 3,201,247. Treatment, alkyl titanate treatment described in British Patent 1,108,559, polyacrylic acid treatment described in German Patent 1,091,433, German Patent 1,134, No. 093 and British Patent No. 1,230,447, polyvinylphosphonic acid treatment, Japanese Patent Publication No. 44-6409, phosphonic acid treatment, US Pat. No. 3,307,951 Phytic acid treatment described in the specification of JP, No. 58-16893 and JP-A No. 58-18291 Treatment with a salt of a molecular compound and a divalent metal, as described in US Pat. No. 3,860,426, hydrophilic cellulose (eg, zinc acetate) containing a water-soluble metal salt (eg, zinc acetate) Carboxymethyl cellulose) is provided with a subbing layer, and a water-soluble polymer having a sulfo group described in JP-A-59-101651.

Further, phosphates described in JP-A No. 62-019494, water-soluble epoxy compounds described in JP-A No. 62-033692, and JP-A No. 62-097892 Phosphoric acid modified starch, diamine compounds described in JP-A-63-056498, inorganic or organic acids of amino acids described in JP-A-63-130391, JP-A-63-145092 Organic phosphonic acids containing a carboxy group or hydroxy group, compounds having an amino group and a phosphonic acid group described in JP-A-63-165183, and JP-A-2-316290 Specific carboxylic acid derivatives, phosphate esters described in JP-A-3-215095, JP-A-3-261592 Compounds having one amino group and one oxygen acid group of phosphorus described in the publication, phosphoric esters described in JP-A-3-215095, and JP-A-5-246171 Aliphatic or aromatic phosphonic acids such as phenylphosphonic acid, compounds containing S atoms such as thiosalicylic acid described in JP-A-1-307745, phosphorus described in JP-A-4-282737 Examples of the treatment include undercoating using a compound having a group of oxygen acids.
Further, coloring with an acid dye described in JP-A-60-64352 can also be performed.

Hydrophilicity can also be achieved by dipping in an aqueous solution of an alkali metal silicate such as sodium silicate or potassium silicate, or by applying a hydrophilic vinyl polymer or hydrophilic compound to form a hydrophilic subbing layer. It is preferable to carry out the treatment.
Hydrophilization treatment with an aqueous solution of an alkali metal silicate such as sodium silicate and potassium silicate is described in US Pat. No. 2,714,066 and US Pat. No. 3,181,461. It can be performed according to methods and procedures.
Examples of the alkali metal silicate include sodium silicate, potassium silicate, and lithium silicate. No. 1 sodium silicate or No. 3 sodium silicate is preferably used, and No. 1 sodium silicate is used. Is more preferable.
When No. 1 sodium silicate is used in the aqueous solution used for the hydrophilization treatment, the concentration of No. 1 sodium silicate is preferably 1 to 10% by mass, and the liquid temperature is preferably 10 to 30 ° C. The treatment time is preferably 1 to 15 seconds.
The aqueous solution of alkali metal silicate may contain an appropriate amount of sodium hydroxide, potassium hydroxide, lithium hydroxide, or the like.
The aqueous solution of alkali metal silicate may contain an alkaline earth metal salt or a Group 4 (Group IVA) metal salt. Examples of the alkaline earth metal salt include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate; sulfates; hydrochlorides; phosphates; acetates; oxalates; Examples of Group 4 (Group IVA) metal salts include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, titanium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride. And zirconium tetrachloride. These alkaline earth metal salts and Group 4 (Group IVA) metal salts are used alone or in combination of two or more.

The amount of Si adsorbed by the alkali metal silicate treatment can be measured by a fluorescent X-ray analyzer, and the amount adsorbed is preferably about 1.0 to 10.0 mg / m ² , and 3 to 10 mg / m 2. ² is more preferable. When the amount of adsorbed Si is 3 to 10 mg / m ² , the stain resistance of the halftone dot portion is improved.
More specifically, in the shadow portion (halftone dot portion) of the printed matter, the area ratio of the halftone dots is high (70 to 90%), and in the area corresponding to that of the planographic printing plate, the image portion (image recording layer) The area is large, and the area of the non-image part (exposed part of the support) is relatively small. In such a case, at the time of printing, the inks placed on the adjacent image parts come into contact with each other (that is, entangled), the ink adheres to the non-image part between them, and the non-image part of the printed material is crushed ( In other words, the phenomenon of contamination) is likely to occur.
However, the hydrophilicity of the non-image part is improved by performing a hydrophilization treatment so that the amount of Si adhering to the surface of the aluminum support is 3 to 10 mg / m ^2. Therefore, the obtained aluminum support is used. Thus, when a lithographic printing plate is prepared and printed, the stain resistance of the halftone dots can be improved.

By the alkali metal silicate treatment described above, the effect of improving the dissolution resistance to the alkaline developer on the surface of the aluminum support is obtained, and the elution of the aluminum component into the developer is suppressed, thereby reducing the fatigue of the developer. It is possible to reduce the occurrence of development debris.
The hydrophilic treatment by forming a hydrophilic undercoat layer can also be performed according to the conditions and procedures described in JP-A Nos. 59-101651 and 60-149491.
Examples of the hydrophilic vinyl polymer used in this method include polyvinyl sulfonic acid, sulfo group-containing vinyl polymerizable compounds such as p-styrene sulfonic acid having a sulfo group, and ordinary vinyl polymerization such as (meth) acrylic acid alkyl ester. And a copolymer with a functional compound. Examples of hydrophilic compounds that may be used in this method include, -NH ₂ group, compounds having at least one selected from the group consisting of -COOH group and sulfo group.

<Dry>
After obtaining the aluminum support as described above, it is preferable to dry the surface of the aluminum support before providing the image recording layer. Drying is preferably performed after the final treatment of the surface treatment, after washing with water and draining with a nip roller.
The drying temperature is preferably 70 ° C or higher, more preferably 80 ° C or higher, preferably 110 ° C or lower, more preferably 100 ° C or lower.
The drying time is preferably 2 to 15 seconds.

[Preparation of lithographic printing plate precursor]
By providing an image recording layer on the aluminum support prepared in the above procedure, the photosensitive lithographic printing plate precursor according to the invention can be obtained. Preferred examples are shown below for the case of providing a thermal negative type image recording layer using a thermal negative photosensitive composition and the case of providing a thermal positive type image recording layer using a thermal positive photosensitive composition.

<Thermal negative type image recording layer>
As a thermal negative type image recording layer provided on an aluminum support, it contains an infrared absorber, a polymerization initiator, a polymerizable compound, and optionally a binder polymer, and further contains a colorant and other optional components as necessary. Including.

The thermal negative type image recording layer is sensitive to a laser corresponding to the absorption wavelength of the sensitizing dye, and therefore can be exposed to various lasers useful for CTP. For example, in the case of using an infrared absorber as a sensitizing dye, the infrared absorber contained therein is in an electronically excited state with high sensitivity to irradiation (exposure) of an infrared laser, and the electrons related to the electronically excited state Movement, energy transfer, heat generation (photothermal conversion function), etc. act on the polymerization initiator coexisting in the recording layer, causing a chemical change in the polymerization initiator to generate radicals.
In this case, the radical generation mechanism is as follows: 1. Heat generated by the photothermal conversion function of the infrared absorber thermally decomposes a polymerization initiator (for example, sulfonium salt) described later to generate radicals. 2. Excited electrons generated by the infrared absorber move to a polymerization initiator (for example, an active halogen compound) to generate radicals. For example, a radical is generated by electron transfer from a polymerization initiator (for example, a borate compound) to an excited infrared absorber. Then, the polymerizable compound causes a polymerization reaction by the generated radical, and the exposed portion is cured to become an image portion.

The thermal negative type image recording layer is particularly suitable for plate making directly drawn with an infrared laser beam having a wavelength of 750 nm to 1400 nm by containing an infrared absorber as a sensitizing dye, Compared to conventional lithographic printing plate precursors, it can exhibit high image forming properties.
Below, each component which comprises a thermal negative type image recording layer is demonstrated.

(Sensitizing dye)
The thermal negative type image recording layer contains a sensitizing dye that absorbs light of a predetermined wavelength that matches the exposure wavelength in laser exposure from the viewpoint of sensitivity.
The exposure of the wavelength that can be absorbed by the sensitizing dye accelerates the radical generation reaction of the polymerization initiator described later and the polymerization reaction of the polymerizable compound thereby. Examples of such a sensitizing dye include a known spectral sensitizing dye or dye, or a dye or pigment that absorbs light and interacts with a photopolymerization initiator. This sensitizing dye becomes a highly sensitive electron excited state by laser exposure of a wavelength suitable for the sensitizing dye, and the electron transfer, energy transfer, etc. related to the electron excited state act on the polymerization initiator described later, and increase the polymerization initiator. It is useful for generating radicals by causing chemical changes with sensitivity.

  Depending on the wavelength of light absorbed by the sensitizing dye, the thermal negative type image recording layer can be sensitive to various wavelengths from ultraviolet rays to visible rays and infrared rays. For example, when an infrared absorber is used as the sensitizing dye, it is sensitive to infrared light having a wavelength of 760 nm to 1200 nm. Further, by using a dye having a maximum absorption wavelength from 350 nm to 450 nm, it is sensitive to blue to purple visible light.

  Spectral sensitizing dyes or dyes preferred as sensitizing dyes used in thermal negative type image recording layers are polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine). B, rose bengal), cyanines (for example, thiacarbocyanine, oxacarbocyanine), merocyanines (for example, merocyanine, carbomerocyanine), thiazines (for example, thionine, methylene blue, toluidine blue), acridines (for example, acridine) Orange, chloroflavin, acriflavine), phthalocyanines (eg, phthalocyanine, metal phthalocyanine), porphyrins (eg, tetraphenylporphyrin, central metal-substituted porphyrin), chlorophyll (For example, chlorophyll, chlorophyllin, central metal-substituted chlorophyll), metal complexes, anthraquinones (for example, anthraquinone), squalium (for example, squalium), and the like, for example, paragraph numbers of JP-A-2005-250438 [0188] to [0258] are described in detail, and the compounds described herein can be appropriately selected and used as a sensitizing dye in the present invention.

In particular, the thermal negative type image recording layer preferably contains an infrared absorber described in detail below as a sensitizing dye.
Infrared absorbers are in an electronically excited state with high sensitivity to infrared laser irradiation (exposure), and heat energy is generated by the photothermal conversion function in addition to the electron transfer and energy transfer related to the previous electron excited state. It is useful for causing a chemical change with high sensitivity by a polymerization initiator.
As an infrared absorber that is a particularly preferable sensitizing dye for use in the thermal negative type image recording layer, a dye or pigment having an absorption maximum at a wavelength of 750 nm to 1400 nm is preferably exemplified.

As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, 58-181690, JP-A-58-194595, etc., methine dyes, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59- No. 73996, JP-A-60-52940, JP-A-60-63744 and the like, Naphthoquinone dyes described in JP-A-58-112792, etc., British Patent 434,875 And cyanine dyes.

Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, US Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. . Moreover, as another example preferable as a dye, the near-infrared absorptive dye described as Formula (I) and (II) in US Patent 4,756,993 can be mentioned.
Other preferred examples of the infrared absorbing dye in the thermal negative type image recording layer include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and particularly preferred examples include cyanine dyes represented by the following general formula (a).

In general formula (a), X ¹ represents a hydrogen atom, a halogen atom, -NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.
In the group shown below, X _a ^- is Z _a which will be described below ^- has the same definition as, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom Represents.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring. Alternatively, it is particularly preferable that a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ^- represents a counter anion. However, when the cyanine dye represented by formula (a) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, from the storage stability of the image recording layer coating solution. , Hexafluorophosphate ions, and aryl sulfonate ions.

  Specific examples of the cyanine dye represented by the general formula (a) that can be suitably used in the thermal negative type image recording layer are described in paragraphs [0017] to [0019] of JP-A No. 2001-133969. Things can be mentioned. Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above. However, a counter ion that does not contain a halogen ion is particularly preferable.

  As pigments used in the thermal negative type image recording layer, commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Applied Technology” (CMC Publishing, published in 1986) and “Printing Ink Technology”, published by CMC Publishing, published in 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Yokoshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. Within this preferred particle size range, excellent dispersion stability of the pigment in the image recording layer can be obtained, and a uniform image recording layer can be obtained.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  When these infrared absorbers are used in the image recording layer, they may be added to the same layer as other components, or another layer may be provided and added thereto.

  The addition amount of these sensitizing dyes, preferably infrared absorbers, is 0.01 to 50% by mass with respect to the total solid content constituting the recording layer from the viewpoint of uniformity in the recording layer and durability of the recording layer. It is preferably in the range of 0.1 to 10% by mass, particularly preferably 0.5 to 10% by mass when a dye is used as a sensitizing dye, and particularly when a pigment is used. Preferably it can add in the ratio of 0.1-10 mass%.

(Polymerization initiator)
The polymerization initiator used in the thermal negative type image recording layer has a function of initiating and advancing the curing reaction of the polymerizable compound described later, and is a thermal decomposition type radical generator that decomposes by heat to generate radicals, infrared rays Gives energy, such as an electron transfer type radical generator that generates radicals by accepting excited electrons of the absorber, or an electron transfer type radical generator that generates electrons by transferring electrons to the excited infrared absorber. Any compound may be used as long as it generates radicals. For example, onium salts, active halogen compounds, oxime ester compounds, borate compounds and the like can be mentioned. These may be used in combination. In the present invention, an onium salt is preferable, and a sulfonium salt is particularly preferable.
Examples of the sulfonium salt polymerization initiator suitably used in the present invention include onium salts represented by the following general formula (I).

In general formula (I), R ¹¹ , R ¹² and R ¹³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. (Z ¹¹ ) ⁻ represents a counter ion selected from the group consisting of halogen ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion, and sulfonate ion, preferably perchloric acid Ions, hexafluorophosphate ions, carboxylate ions, and aryl sulfonate ions.

  Specific examples ([OS-1] to [OS-12]) of the onium salt represented by the general formula (I) are shown below, but are not limited thereto.

  In addition to the above, specific aromatic sulfonium salts described in JP-A Nos. 2002-148790, 2002-148790, 2002-350207, and 2002-6482 are also preferably used.

  In the thermal negative type image recording layer, in addition to the sulfonium salt polymerization initiator, other polymerization initiators (other radical generators) can be used. Other radical generators include onium salts other than sulfonium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazides, active halogen compounds, oxime ester compounds, triaryls. Examples thereof include monoalkyl borate compounds. Among them, onium salts are preferable because of their high sensitivity. Moreover, these polymerization initiators (radical generators) can be used in combination with the sulfonium salt polymerization initiator as an essential component.

Other onium salts that can be suitably used in the thermal negative type image recording layer include iodonium salts and diazonium salts. In the thermal negative type image recording layer, these onium salts function not as acid generators but as radical polymerization initiators.
Other onium salts in the lithographic printing plate precursor (1) include onium salts represented by the following general formulas (II) and (III).

In general formula (II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a carbon atom having 12 or less carbon atoms. An aryloxy group is mentioned. (Z ²¹ ) ⁻ represents a counter ion having the same meaning as (Z ¹¹ ) ⁻ .

In the general formula (III), Ar ³¹ represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. (Z ³¹ ) ⁻ represents a counter ion having the same meaning as (Z ¹¹ ) ⁻ .

  The onium salts represented by the general formula (II) ([OI-1] to [OI-10]) and the general formula (III) that can be suitably used in the thermal negative type image recording layer are shown below. Specific examples of the onium salts ([ON-1] to [ON-5]) are given, but the invention is not limited thereto.

Specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) in a thermal negative type image recording layer include those described in JP-A No. 2001-133696.
The polymerization initiator (radical generator) used in the thermal negative type image recording layer preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.

  The total content of the polymerization initiator in the thermal negative type image recording layer is 0.1 to 50% by mass with respect to the total solid content constituting the recording layer, from the viewpoint of sensitivity and occurrence of smudges in the non-image area during printing, Preferably it is 0.5-30 mass%, Most preferably, it is 1-20 mass%.

As the polymerization initiator in the thermal negative type image recording layer, only one kind may be used, or two or more kinds may be used in combination. When two or more polymerization initiators are used in combination, for example, a plurality of suitably used sulfonium salt polymerization initiators may be used, or a sulfonium salt polymerization initiator and another polymerization initiator may be used in combination. Also good.
When the sulfonium salt polymerization initiator and another polymerization initiator are used in combination, the content ratio (mass ratio) is preferably 100/1 to 100/50, more preferably 100/5 to 100/25.
Moreover, a polymerization initiator may be added to the same layer as other components, or another layer may be provided and added thereto.

  When a highly sensitive sulfonium salt polymerization initiator, which is preferable as a polymerization initiator, is used for the thermal negative type image recording layer, the radical polymerization reaction proceeds effectively, and the strength of the formed image area becomes very high. . Therefore, combined with the high oxygen blocking function of the protective layer described later, a lithographic printing plate having high image area strength can be produced, and as a result, printing durability is further improved. In addition, since the sulfonium salt polymerization initiator itself is excellent in stability over time, even when the produced lithographic printing plate precursor is stored, the occurrence of an undesirable polymerization reaction is effectively suppressed. Will also have.

(Polymerizable compound)
The polymerizable compound used in the thermal negative type image recording layer is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and a compound having at least one, preferably two or more ethylenically unsaturated bonds Chosen from. Such compound groups are widely known in the industrial field, and these can be used without particular limitation in the thermal negative type image recording layer. These have chemical forms such as monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP-A-59-5241. Those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula to a polyisocyanate compound having two or more isocyanate groups. Can be mentioned.

CH ₂ = C (R ^a ) COOCH ₂ CH (R ^b ) OH... General formula (where R ^a and R ^b represent H or CH ₂ )

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable. Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238, It is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337 and JP-B-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like can also be mentioned. . In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the final performance design. For example, it is selected from the following viewpoints. From the viewpoint of photosensitive speed, a structure having a high unsaturated group content per molecule is preferred, and in many cases, a bifunctional or higher functionality is preferred. Further, in order to increase the strength of the image portion, that is, the cured film, those having three or more functionalities are preferable, and further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, A method of adjusting both photosensitivity and strength by using a vinyl ether compound) is also effective. A compound having a large molecular weight or a compound having high hydrophobicity is excellent in photosensitive speed and film strength, but is not preferable in terms of development speed and precipitation in a developer. In addition, the selection and use method of the addition polymerization compound is also an important factor for compatibility and dispersibility with other components in the recording layer composition (for example, binder polymer, initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination.
In the thermal negative type image recording layer, a specific structure described later may be selected for the purpose of improving adhesion to an aluminum support or a protective layer.

Regarding the content of the addition polymerizable compound in the image recording layer, the solid content in the recording layer composition is selected from the viewpoints of sensitivity, occurrence of phase separation, adhesiveness of the recording layer, and precipitation from the developer. On the other hand, it is preferably used in the range of 5 to 80% by mass, more preferably 40 to 75% by mass.
These may be used alone or in combination of two or more. In addition, as for the method of using the addition polymerizable compound, an appropriate structure, blending, and addition amount can be arbitrarily selected from the viewpoints of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface tackiness, and the like. Further, in the case of a thermal negative type image recording layer, a layer configuration / coating method such as undercoating or overcoating can be carried out.

(Binder polymer)
The binder polymer used in the thermal negative type image recording layer is contained from the viewpoint of improving the film property, and various types can be used as long as it has a function of improving the film property. Can do. Especially, as a binder polymer suitable in this invention, it is a binder polymer which has a repeating unit represented by the following general formula (i). Hereinafter, the binder polymer having the repeating unit represented by the general formula (i) is appropriately referred to as a specific binder polymer and will be described in detail.

(In the general formula (i), R ¹ represents a hydrogen atom or a methyl group, and R ² contains two or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. And a linking group having a total number of atoms of 2 to 82. A represents an oxygen atom or —NR ³ —, and R ³ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. N represents an integer of 1 to 5.)

First, R ¹ in the general formula (i) represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

The linking group represented by R ² in the general formula (i) includes two or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. The number is 2 to 82, preferably 2 to 50, and more preferably 2 to 30. The total number of atoms shown here refers to the number of atoms including the substituent when the linking group has a substituent. More specifically, the number of atoms constituting the main skeleton of the linking group represented by R ² is preferably 1-30, more preferably 3-25, and 4-20. More preferred is 5-10. In the present specification, the “main skeleton of the linking group” refers to an atom or an atomic group that is used only for linking A and the terminal COOH in the general formula (i). In some cases, it refers to an atom or atomic group that constitutes a path with the fewest number of atoms used. Therefore, when a linking group has a ring structure, the number of atoms to be included differs depending on the linking site (for example, o-, m-, p-, etc.).

More specific examples include alkylene, substituted alkylene, arylene, substituted arylene, and the like, and a structure in which a plurality of these divalent groups are linked by an amide bond or an ester bond may be used.
Examples of the linking group having a chain structure include ethylene and propylene. A structure in which these alkylenes are linked via an ester bond can also be exemplified as a preferable example.

Among these, the linking group represented by R ² in the general formula (i) is preferably an (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure having 3 to 30 carbon atoms. More specifically, a compound having an aliphatic cyclic structure such as cyclopropane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, dicyclohexyl, tercyclohexyl, norbornane and the like, which may be substituted by one or more arbitrary substituents And (n + 1) valent hydrocarbon groups by removing (n + 1) hydrogen atoms on an arbitrary carbon atom constituting. R ² preferably has 3 to 30 carbon atoms including a substituent.

One or more arbitrary carbon atoms of the compound constituting the aliphatic cyclic structure may be replaced with a heteroatom selected from a nitrogen atom, an oxygen atom, or a sulfur atom. In terms of printing durability, R ² represents a condensed polycyclic aliphatic hydrocarbon, a bridged cyclic aliphatic hydrocarbon, a spiro aliphatic hydrocarbon, an aliphatic hydrocarbon ring assembly (a plurality of rings are connected by a bond or a linking group). A (n + 1) valent hydrocarbon group having an aliphatic cyclic structure which may have a substituent of 5 to 30 carbon atoms containing two or more rings. . Also in this case, the carbon number includes the carbon atom of the substituent.

As the linking group represented by R ² , those having 5 to 10 atoms constituting the main skeleton of the linking group are particularly preferred, and are structurally a chain structure, and an ester bond in the structure. And those having a cyclic structure as described above are preferred.

Examples of the substituent that can be introduced into the linking group represented by R ² include monovalent nonmetallic atomic groups other than hydrogen, such as halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups. Group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N- Diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy , Arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-aryl Ureido group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N ′ -Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N ' -Aryl-N-arylureido group, N ', N'-diaryl-N-alkylureido group, N', N'-diaryl-N-arylureido group, N'-al Kill-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group and its conjugate base group, Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, Alkylsulfinyl group An arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO ₃ H) and its conjugated base group, alkoxy sulfonyl group, aryloxy sulfonyl group, sulfinamoyl group, N- alkylsulfinamoyl group, N, N- Dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N -Dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, N-acylsulfamoyl group and its conjugate base group, N- alkylsulfonylsulfamoyl group (-SO ₂ NHSO ₂ alkyl)) and its conjugated base group, N- aryl sulfonylsulfamoyl group _{(-SO 2 NHSO 2 (aryl)} ) and its conjugated base group, N- alkylsulfonylcarbamoyl group (-CONHSO ₂ (alkyl)) and its conjugate Base group, N-arylsulfonylcarbamoyl group (—CONHSO ₂ (aryl)) and its conjugate base group, alkoxysilyl group (—Si (Oalkyl) ₃ ), aryloxysilyl group (—Si (Oaryl) ₃ ), hydroxysilyl Group (—Si (OH) ₃ ) and its conjugate base group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group, dialkylphosphono group (—PO ₃ (alkyl) ₂ ), diarylphosphono group (— PO ₃ (aryl) _2), alkyl aryl phosphono group _{(-PO 3 (alkyl) (aryl} )) , Monoalkylphosphono group (—PO ₃ H (alkyl)) and its conjugate base group, monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group, phosphonooxy group (—OPO ₃ H ₂ ) And its conjugate base group, dialkylphosphonooxy group (—OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (—OPO ₃ (aryl) ₂ ), alkylarylphosphonooxy group (—OPO ₃ (alkyl) ( aryl)), monoalkylphosphonooxy group (—OPO ₃ H (alkyl)) and its conjugate base group, monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group, cyano group, nitro group, group, ₍₂ -B (alkyl)) dialkyl boryl group, Jiariruboriru group (-B (aryl) _2), alkyl aryl boryl -B (alkyl) (aryl)) , dihydroxy boryl group (-B (OH) ₂₎ and its conjugated base group, an alkyl hydroxy boryl group (-B (alkyl) (OH) ) and its conjugated base group, an aryl hydroxy boryl And the group (—B (aryl) (OH)) and its conjugate base group, aryl group, alkenyl group and alkynyl group.

  In the thermal negative type image recording layer, depending on the design of the recording layer, a substituent having a hydrogen atom capable of hydrogen bonding, particularly a substituent having an acid dissociation constant (pKa) smaller than that of a carboxylic acid, This is not preferable because the printing durability tends to be lowered. On the other hand, hydrophobic substituents such as halogen atoms, hydrocarbon groups (alkyl groups, aryl groups, alkenyl groups, alkynyl groups), alkoxy groups, aryloxy groups and the like are more preferable because they tend to improve printing durability. When the cyclic structure is a monocyclic aliphatic hydrocarbon having 6 or less members such as cyclopentane or cyclohexane, it preferably has such a hydrophobic substituent. If possible, these substituents may be bonded to each other or with a substituted hydrocarbon group to form a ring, and the substituent may be further substituted.

R ³ in the case where A in formula (i) is NR ³ — represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ³ include an alkyl group, an aryl group, an alkenyl group, and an alkynyl group.
Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, isobutyl, sec-butyl, 1 carbon number such as tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-norbornyl group Up to 10 linear, branched or cyclic alkyl groups.
Specific examples of the aryl group include carbon having one heteroatom selected from the group consisting of an aryl group having 1 to 10 carbon atoms such as a phenyl group, a naphthyl group, and an indenyl group, a nitrogen atom, an oxygen atom, and a sulfur atom. Examples include heteroaryl groups of 1 to 10, such as a furyl group, a thienyl group, a pyrrolyl group, a pyridyl group, and a quinolyl group.
Specific examples of the alkenyl group include those having 1 to 10 carbon atoms such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group, 1-cyclohexenyl group and the like. A linear, branched, or cyclic alkenyl group is mentioned.
Specific examples of the alkynyl group include alkynyl groups having 1 to 10 carbon atoms such as ethynyl group, 1-propynyl group, 1-butynyl group, and 1-octynyl group. The substituent that R ³ may have is the same as those exemplified as the substituent that R ² can introduce. The number of carbon atoms of R ³ is 1 to 10 including the carbon number of the substituent.

  A in the general formula (i) is preferably an oxygen atom or —NH— because synthesis is easy.

  N in the general formula (i) represents an integer of 1 to 5, and is preferably 1 in terms of printing durability.

  Although the preferable specific example of the repeating unit represented by general formula (i) below is shown, this invention is not limited to these.

  One type of repeating unit represented by the general formula (i) may be contained in the binder polymer, or two or more types may be contained. The specific binder polymer in the present invention may be a polymer composed only of the repeating unit represented by the general formula (i), but is usually used as a copolymer in combination with other copolymerization components. The total content of the repeating unit represented by the general formula (i) in the copolymer is appropriately determined depending on the structure thereof, the design of the recording layer composition, and the like, but preferably 1 to 99 with respect to the total molar amount of the polymer component. It is contained in the range of mol%, more preferably 5 to 40 mol%, still more preferably 5 to 20 mol%.

  As a copolymerization component in the case of using as a copolymer, a conventionally well-known thing can be used without a restriction | limiting, if it is a monomer which can be radically polymerized. Specific examples include monomers described in “Polymer Data Handbook—Basic Edition” (Edition of Polymer Society, Bafukan, 1986). One type of such copolymerization component may be used, or two or more types may be used in combination.

  The molecular weight of the specific binder polymer in the thermal negative type image recording layer is appropriately determined from the viewpoint of image formability and printing durability. The molecular weight is preferably in the range of 2,000 to 1,000,000, more preferably 5,000 to 500,000, and still more preferably 10,000 to 200,000.

  The binder polymer used in the thermal negative type image recording layer may be a specific binder polymer alone, or may be used as a mixture by combining one or more other binder polymers. The binder polymer used in combination is used in the range of 1 to 60% by mass, preferably 1 to 40% by mass, and more preferably 1 to 20% by mass with respect to the total mass of the binder polymer component. As the binder polymer that can be used in combination, a conventionally known binder polymer can be used without limitation, and specifically, an acrylic main chain binder, a urethane binder, or the like often used in the industry is preferably used.

The total amount of the specific binder polymer in the image recording layer and the binder polymer that may be used in combination can be determined as appropriate. %, Preferably 20 to 80% by mass, more preferably 30 to 70% by mass.
Moreover, as an acid value (meg / g) of such a binder polymer, it is preferable that it is the range of 2.00-3.60.

-Other binder polymers that can be used together-
The other binder polymer that can be used in combination with the specific binder polymer is preferably a binder polymer having a radical polymerizable group.
The radical polymerizable group is not particularly limited as long as it can be polymerized by radicals, but α-substituted methylacrylic group [—OC (═O) —C (—CH ₂ Z) ═CH ₂ , Z = A hydrocarbon group starting from a hetero atom], an acryl group, a methacryl group, an allyl group, and a styryl group. Among these, an acryl group and a methacryl group are preferable.
The content of the radical polymerizable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 1 g per binder polymer from the viewpoint of sensitivity and storage stability. It is 10.0 mmol, More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol.

  Further, the other binder polymer that can be used in combination is preferably one having an alkali-soluble group. The content of alkali-soluble groups in the binder polymer (acid value by neutralization titration) is preferably from 0.1 to 3.0 mmol, more preferably from 1 to 3.0 g of binder polymer, from the viewpoints of precipitation of developing residue and printing durability. Is 0.2 to 2.0 mmol, most preferably 0.45 to 1.0 mmol.

  The mass average molecular weight of such a binder polymer is preferably from 2,000 to 1,000,000, more preferably from 10,000 to 300, from the viewpoints of film properties (press life) and solubility in a coating solvent. In the range of 20,000 to 200,000.

Further, the glass transition point (Tg) of such a binder polymer is preferably 70 to 300 ° C., more preferably 80 to 250 ° C., and most preferably 90 to 90 ° C. from the viewpoints of storage stability, printing durability, and sensitivity. It is in the range of 200 ° C.
As a means for increasing the glass transition point of the binder polymer, the molecule preferably contains an amide group or an imide group, and particularly preferably contains a methacrylamide or a methacrylamide derivative.

(Other ingredients)
In addition to the above basic components, other components suitable for the application, production method, and the like can be appropriately added to the thermal negative type image recording layer. Hereinafter, preferred additives will be exemplified.

-Colorant-
A dye or pigment may be added to the thermal negative type image recording layer for the purpose of coloring. As a result, it is possible to improve the so-called plate inspection properties such as the visibility of the image after plate making as a printing plate and the suitability of an image density measuring machine. Specific examples of the colorant include pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone dyes, and cyanine dyes. Among them, a cationic dye is preferable.
The addition amount of the dye and the pigment as the colorant is preferably about 0.5% by mass to about 5% by mass with respect to the non-volatile components in the entire recording layer composition.

-Polymerization inhibitor-
It is desirable to add a small amount of a thermal polymerization inhibitor to the thermal negative type image recording layer in order to prevent unnecessary thermal polymerization of a polymerizable compound having an ethylenically unsaturated double bond, that is, a polymerizable compound. . Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the nonvolatile component in the image recording layer. If necessary, a higher fatty acid derivative such as behenic acid or behenic acid amide or the like may be added to prevent polymerization inhibition by oxygen and may be unevenly distributed on the surface of the layer in the course of drying after coating. The addition amount of the higher fatty acid derivative is preferably about 0.5% by mass to about 10% by mass with respect to the nonvolatile component in the image recording layer.

-Other additives-
Furthermore, in the thermal negative type image recording layer, known additions such as inorganic fillers for improving the physical properties of the cured film, other plasticizers, and oil sensitizers that can improve the ink deposition property of the recording layer surface, etc. An agent may be added. Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, and addition polymerization with binder polymer. Generally, it can be added in a range of 10% by mass or less based on the total mass with the compound.
In addition, in order to enhance the effect of heating and exposure after development for the purpose of improving the film strength (printing durability), a thermal negative type image recording layer may be added with a UV initiator or a thermal crosslinking agent. It can be carried out.

<Thermal positive type image recording layer>
Examples of the thermal positive type image recording layer include those containing a water-insoluble and alkali-soluble polymer compound (hereinafter referred to as “alkali-soluble polymer compound”) and a photothermal conversion substance. In the thermal positive type image recording layer, the photothermal conversion substance converts the energy of light such as infrared lasers into heat, which effectively eliminates the interaction that reduces the alkali solubility of alkali-soluble polymer compounds. To do.

Examples of the alkali-soluble polymer compound include a resin containing an acidic group in the molecule and a mixture of two or more thereof. In particular, a phenolic hydroxy group, sulfonamide group (in -SO ₂ NH-R (wherein, R represents a hydrocarbon group.)), Active imino group _{(-SO 2 NHCOR, -SO 2 NHSO} 2 R, -CONHSO A resin having an acidic group such as ₂ R (wherein R has the same meaning as described above) is preferable in terms of solubility in an alkali developer.
In particular, a resin having a phenolic hydroxy group is preferable in that it has excellent image-forming properties when exposed to light such as an infrared laser. For example, phenol-formaldehyde resin, m-cresol-formaldehyde resin, p-cresol-formaldehyde resin, Novolak resins such as m- / p-mixed cresol-formaldehyde resin, phenol / cresol (any of m-, p- and m- / p-mixed) mixed-formaldehyde resin (phenol-cresol-formaldehyde co-condensation resin) Are preferable.
Furthermore, the polymer compound described in JP-A No. 2001-305722 (particularly [0023] to [0042]), and the repetition represented by the general formula (1) described in JP-A No. 2001-215893 Preferred examples also include polymer compounds containing units, and polymer compounds described in JP-A No. 2002-311570 (particularly [0107]).

  Preferable examples of the photothermal conversion substance include pigments or dyes having a light absorption region in the infrared region having a wavelength of 700 to 1200 nm from the viewpoint of recording sensitivity. Examples of the dye include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes (for example, , Nickel thiolate complex). Among these, cyanine dyes are preferable, and cyanine dyes represented by the general formula (I) described in JP 2001-305722 A are particularly preferable.

The thermal positive type image recording layer may contain a dissolution inhibitor. As the dissolution inhibitor, for example, dissolution inhibitors described in JP-A-2001-305722, [0053] to [0055] are preferably exemplified.
Further, in the thermal positive type image recording layer, as additives, a sensitivity modifier, a printing agent for obtaining a visible image immediately after heating by exposure, a compound such as a dye as an image colorant, coating properties and It is preferable to contain a surfactant for improving the processing stability. For these, compounds described in JP-A-2001-305722, [0056] to [0060] are preferable.
In addition to the above points, the photosensitive composition described in detail in JP-A No. 2001-305722 is preferably used for the image recording layer.

Further, the thermal positive type image recording layer is not limited to a single layer but may have a two-layer structure.
As an image recording layer having a two-layer structure (multilayer image recording layer), a lower layer (hereinafter referred to as “A layer”) having excellent printing durability and solvent resistance is provided on the side close to the support, and a positive layer is provided thereon. A type provided with a layer having excellent image formability (hereinafter referred to as “B layer”) is preferable. This type has high sensitivity and can realize a wide development latitude. The B layer generally contains a photothermal conversion substance. Preferred examples of the photothermal conversion substance include the dyes described above.
As the resin used in the A layer, a polymer having a monomer having a sulfonamide group, an active imino group, a phenolic hydroxy group or the like as a copolymerization component is preferably used because it has excellent printing durability and solvent resistance. . As the resin used for the B layer, an alkaline aqueous solution-soluble resin having a phenolic hydroxy group is preferably exemplified.
In addition to the resin, the composition used for the A layer and the B layer can contain various additives as necessary. Specifically, various additives as described in JP-A-2002-3233769, [0062] to [0085] are preferably used. Further, the additives described in [0053] to [0060] of JP-A-2001-305722 described above are also preferably used.
About each component which comprises A layer and B layer, and its content, it is preferable to make it describe in Unexamined-Japanese-Patent No. 11-218914.

<Intermediate layer>
An intermediate layer is preferably provided between the thermal positive type image recording layer and the aluminum support. As the component contained in the intermediate layer, various organic compounds described in [0068] of JP-A No. 2001-305722 are preferably exemplified.

<Others>
As a method for producing a thermal positive type image recording layer and a plate making method, methods described in detail in JP-A No. 2001-305722 can be used.

<Protective layer of image recording layer>
The above-described thermal negative type image recording layer and thermal positive type image recording layer are usually exposed to the atmosphere in the air, and oxygen, moisture, basic substances, etc. present in the atmosphere that inhibit the image formation reaction. For the purpose of preventing the low molecular weight compound from being mixed into the image recording layer, a protective layer is preferably provided on the image recording layer.
As the protective layer provided for such a purpose, a protective layer containing organic resin fine particles whose surface is coated with silica (hereinafter, appropriately referred to as silica-coated fine particles) and a hydrophilic polymer is preferable.
As the protective layer provided on the thermal positive type image recording layer, those described in JP-A-2002-3233769 can also be preferably used.

  By containing a hydrophilic polymer, preferably a hydrophilic polymer mainly composed of polyvinyl alcohol, and organic resin fine particles coated with silica on the protective layer provided for such purpose, The stability of the organic resin fine particles in the coating solution is dramatically increased, and the lithographic printing plate precursor having a protective layer formed using this coating solution can always achieve excellent film strength. Matte properties can be imparted to the. As a result, the protective layer can not only improve sensitivity, but also improve storage stability over time and improve safelight suitability, and can suppress deterioration due to deformation or the like and generation of scratches. In addition, since excellent matting properties are imparted to the protective layer, when a planographic printing plate precursor is laminated, the adhesion and protection between the protective layer surface of the planographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor are protected. It becomes possible to suppress scratches generated between the surface of the layer and the back surface of the aluminum support.

As described above, since the protective layer can impart matting properties, it needs to be present as the uppermost layer of the lithographic printing plate precursor.
Further, in the case where the protective layer is a single layer, the protective layer contains a mica compound in any one of a plurality of layers forming the protective layer when the protective layer has a laminated structure. This is preferable from the viewpoint of improving various properties of oxygen barrier properties, external pressure resistance, and adhesion resistance.
Hereinafter, each component used for a protective layer is demonstrated one by one.

(Silica-coated organic resin fine particles)
Silica-coated fine particles are formed by coating fine particles of an organic resin with silica. Organic resin fine particles that serve as the core suppress the adhesion between the protective layer surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor and the rubbing scratch that occurs between the protective layer surface and the back surface of the aluminum support. To be added. The basic characteristics desired for such fine particles that act as a matting agent are that the transmission of light used for exposure is not substantially inhibited, and it does not soften or become sticky depending on the moisture and temperature in the air. It is preferably a resin that is added to the protective layer to impart appropriate irregularities to its surface and reduce the adhesion surface area.

Further, from the viewpoint of suppressing scratching, it is preferable that the particles acting as a matting agent can relieve stress generated when rubbing with a hard Al surface. Furthermore, the fine particles have a hydrophilic polymer that serves as a binder for the protective layer, and preferably have a high affinity with general-purpose polyvinyl alcohol in the protective layer, are well kneaded in the film, and are detached from the film surface even after the film is formed. Difficult ones are preferred.
As the organic resin constituting the organic resin fine particles serving as the core of the silica-coated fine particles, any resin having the physical properties as described above can be used without limitation, for example, polyacrylic acid resin, polyurethane resin, Examples include polystyrene resins, polyester resins, epoxy resins, phenol resins, melamine resins, and silicone resins. Of these, polyacrylic acid resins, polyurethane resins, and melamine resins are preferable from the viewpoint of affinity with polyvinyl alcohol, which is a preferred binder.

Further, as a material for forming a silica layer covering the surface of the organic resin fine particles, compounds having an alkoxysilyl group such as a condensate of an alkoxysiloxane compound, in particular, a siloxane material used in a sol-gel method, specifically Specifically, silica fine particles such as silica sol, colloidal silica, silica nanoparticles and the like are preferable.
Regarding the constitution of the silica-coated fine particles, even if the silica fine particles adhere to the surface of the organic resin fine particles as a solid component, a condensation reaction of the alkoxysiloxane compound was performed to form a siloxane compound layer on the surface of the organic resin fine particles. It may be a thing.

The silica does not necessarily have to cover the entire surface of the organic resin fine particles, and the effect of the present invention can be obtained if the surface is coated at an amount of 0.5% by mass or more with respect to at least the organic resin fine particles. That is, the presence of silica on at least a part of the surface of the organic resin fine particles achieves an improved affinity with PVA on the surface of the organic fine particles, and even when subjected to external stress, the fine particles are prevented from falling off and have excellent scratch resistance. And adhesion resistance can be maintained. For this reason, “silica coating” in the present specification includes a state in which silica is present on at least a part of the surface of the organic resin fine particles.
The surface coating state of silica can be confirmed by morphological observation with a scanning electron microscope (TEM) or the like, and the silica coating amount is detected by detecting Si atoms by elemental analysis such as fluorescent X-ray analysis. This can be confirmed by calculating the amount of silica present.

  The method for producing the silica-coated fine particles is not particularly limited, and is a method in which the silica surface coating layer is formed simultaneously with the formation of the organic resin fine particles by coexisting the silica fine particles or the silica precursor compound with the monomer component as the raw material of the resin fine particles. Alternatively, after forming the organic resin fine particles, the silica fine particles may be physically attached to the surface and then fixed.

  To give an example of the production method, first, in water containing a water-soluble polymer such as polyvinyl alcohol, methylcellulose, polyacrylic acid, and a suspension stabilizer appropriately selected from inorganic suspensions such as calcium phosphate and calcium carbonate. Silica and a raw material resin (more specifically, a monomer capable of suspension polymerization, a prepolymer capable of suspension crosslinking, or a raw material resin such as a resin liquid constituting the organic resin described above) are added. Then, stirring and mixing are performed to prepare a suspension in which silica and the hydrophobic raw material resin are dispersed. At that time, an emulsion (suspension) having a target particle size can be formed by adjusting the type of suspension stabilizer, its concentration, the number of stirring revolutions, and the like. Next, the suspension is heated to start the reaction, and resin particles are produced by suspension polymerization or suspension crosslinking of the resin raw material. At this time, the coexisting silica is fixed to the resin particles that are cured by polymerization or cross-linking reaction, particularly near the surface of the resin particles due to the physical properties thereof. Thereafter, this is subjected to solid-liquid separation, and the suspension stabilizer attached to the particles is removed by washing, followed by drying. Thereby, substantially spherical organic resin particles having a desired particle size on which silica is immobilized are obtained.

  In this way, it is possible to obtain a resin of a desired size by controlling the conditions during suspension polymerization or suspension crosslinking. However, silica-adhered organic resin fine particles can be produced without strict control. Then, silica-coated fine particles having a desired size can be obtained by a mesh filtration method.

  When the total amount of the raw material resin and silica is 100 parts by weight, the addition amount of the raw material in the mixture when the silica-coated fine particles are produced by the above method is stable in suspension in 200 to 800 parts by weight of water as a dispersion medium. 0.1 to 20 parts by weight of the agent is added and sufficiently dissolved or dispersed, and the mixture of 100 parts by weight of the raw material resin and silica is added to the liquid so that the dispersed particles have a predetermined particle size. After adjusting the particle size, the liquid temperature is raised to 30 to 90 ° C. and reacted for 1 to 8 hours.

  As for the method for producing silica-coated fine particles, the above-described method is an example, and for example, JP 2002-327036 A, JP 2002-173410 A, JP 2004-307837 A, JP 2006-38246 A, and the like. Any of the silica-coated fine particles described in detail in the above and obtained by the method described herein can be suitably used for a lithographic printing plate precursor.

  Further, silica-coated fine particles that can be used for the protective layer are also available as commercial products. Specific examples of the silica-coated fine particles include silica / melamine composite fine particles, such as Nissan Chemical Industries Co., Ltd. Opt Bead 2000M, Opt Bead 3500M, Examples thereof include opt beads 6500M, opt beads 10500M, opt beads 3500S, and opt beads 6500S. As silica / acrylic composite fine particles, Negami Industrial Co., Ltd. Art Pearl G-200 transparent, Art Pearl G-400 transparent, Art Pearl G-800 transparent, Art Pearl GR-400 transparent, Art Pearl GR-600 transparent, Art Pearl GR-800 transparent, Art Pearl J-7P. As the silica / urethane composite fine particles, Negami Industrial Co., Ltd. Art Pearl C-400 Transparent, C-800 Transparent, P-800T, U-600T, U-800T, CF-600T, CF800T, Dainichi Seika Co., Ltd. Dynamic Examples thereof include beads CN5070D and dampula coat THU.

The shape of the silica-coated fine particles is preferably a true spherical shape, but may be a so-called spindle shape having a flat plate shape or an elliptical projection.
The average particle diameter is preferably 1 to 30 μmφ, more preferably 1.5 to 20 μmφ, and most preferably 2 to 15 μmφ. In this range, a sufficient spacer function and mat performance can be expressed, the fixation to the surface of the protective layer is easy, and the holding function is excellent against contact stress from the outside.
A preferable addition amount of the silica-coated fine particles in the protective layer is 5 to 1000 mg / m ² , more preferably 10 to 500 mg / m ² , and most preferably 20 to 200 mg / m ² .
Moreover, as a preferable addition amount with respect to the whole protective layer, it is preferable that it is 0.5-95 mass% with respect to the protective layer total solid, It is more preferable that it is 1-50 mass%, Most preferably, it is 2 It is in the range of 20% by mass.

(Other organic resin fine particles)
In the protective layer, in addition to the silica-coated organic resin fine particles, other organic resin fine particles (having no silica coating layer) can be used in combination as long as the effects of the present invention are not impaired.
Organic resin fine particles that can be used in combination include poly (meth) acrylates, polystyrene and derivatives thereof, polyamides, polyimides, polyolefins such as low density polyethylene, high density polyethylene, and polypropylene, polyurethanes, polyureas, and polyesters. Preferred are fine particles made of synthetic resins such as, and fine particles made of natural polymers such as chitin, chitosan, cellulose, crosslinked starch, and crosslinked cellulose.
Among these, the synthetic resin fine particles have advantages such as easy particle size control and easy control of desired surface characteristics by surface modification.

As for the method for producing organic resin fine particles, a relatively hard resin such as PMMA can be finely divided by a crushing method. However, a method of synthesizing particles by an emulsion / suspension polymerization method is preferable. Currently adopted in the mainstream due to ease of control and accuracy.
The production method of these fine particle powders is “Ultra Fine Particles and Materials”, published by the Japan Society for Materials Science, published in 1993, “Manufacture and Application of Fine Particles / Powder”, supervised by Haruma Kawaguchi, and published by CMC Publishing 2005. Are described in detail.

  Organic resin fine particles that can be used in combination with silica-coated fine particles in the protective layer are also available as commercial products. For example, cross-linked acrylic resins MX-300, MX-500, MX-1000, MX-1500H, manufactured by Soken Chemical Co., Ltd. MR-2HG, MR-7HG, MR-10HG, MR-3GSN, MR-5GSN, MR-7G, MR-10G, MR-5C, MR-7GC, styryl resin-based SX-350H, SX-500H, Sekisui Acrylic resin manufactured by Seiko Seisakusho, MBX-5, MBX-8, MBX-12MBX-15, MBX-20, MB20X-5, MB30X-5, MB30X-8, MB30X-20, SBX-6, SBX-8, SBX- 12, SBX-17 Mitsui Chemicals polyolefin resin, Chemipearl W100, W200, W300, W308, W31 , W400, W401, W405, W410, W500, WF640, W700, W800, W900, W950, WP100, and the like.

The true specific gravity of other organic resin fine particles contained as an optional component in the protective layer is in the range of 0.90 to 1.30, the average particle diameter is preferably 2.0 to 15 μm, and the true specific gravity is 0. It is in the range of .90 to 1.20, more preferably 3.0 to 12 μm.
1.0-30 mass% is preferable and, as for content in the protective layer solid content of these particle | grains, 2.0-20 mass% is more preferable. Moreover, it is preferable that it is the range of 5.0-50 mass% with respect to the silica covering fine particle which is an essential component.
When these organic resin fine particles as an optional component are used in combination, the surface mat effect, the adhesion preventing effect and the scratch resistance effect are improved. There is a concern that the organic fine particles may be easily detached from the surface of the protective layer.

(Hydrophilic polymer)
The binder for forming the protective layer is not particularly limited as long as it can form a uniform film, but it is required to be hydrophilic from the viewpoint of removability, and from the viewpoint of detailed description below. A water-soluble polymer is preferred. However, the present invention is not limited thereto, and a water-insoluble polymer can be appropriately selected and used in combination as long as the effects of the present invention are not impaired.
Specific examples of various polymers that can be used as the binder of the protective layer include, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, polyvinyl acetate partially saponified product, ethylene- Vinyl alcohol copolymers, water-soluble cellulose derivatives, gelatin, starch derivatives, water-soluble polymers such as gum arabic, polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, cellophane And the like. These may be used in combination of two or more as required.

Among them, the binder polymer used for forming the protective layer is excellent in adhesion to the image recording layer, its surface (outermost surface) has low adhesion to other materials, and is a development step after exposure. Polymers that can be easily removed are preferred.
From such a viewpoint, the binder component of the protective layer is preferably a water-soluble polymer among hydrophilic polymers, and particularly preferably polyvinyl alcohol as a main component. Polyvinyl alcohol has an excellent film-forming property and a relatively low adhesion surface.

Polyvinyl alcohol (PVA) used as a preferred water-soluble polymer in the protective layer is preferably a compound having a saponification degree of 85 to 99, preferably 91.0 to 99. If the degree of saponification is within this range, it may have any structure as long as it contains an unsubstituted vinyl alcohol unit for having a necessary oxygen barrier property and a low adhesion surface. That is, a part of the polyvinyl alcohol may be substituted with ester, ether, acetal, etc., a part thereof may be modified, and it may contain other copolymer components. May be.
Generally, the higher the degree of saponification of the PVA used, in other words, the higher the content of unsubstituted vinyl alcohol units, the higher the oxygen barrier property. For this reason, it is preferable that the protective layer has, for example, polyvinyl alcohol having a saponification degree of 91 mol% or more as a main component, and as described later, the protective layer can be protected by using a mica compound in combination with any of the protective layers. The oxygen barrier property of the layer is further improved.

  Polyvinyl alcohol having a polymerization degree in the range of 200 to 2400 is preferable. Such a polymer is also available as a commercial product, specifically, PVA-102, PVA-103, PVA-104, PVA-105, PVA-110, PVA-117, PVA manufactured by Kuraray Co., Ltd. -120, PVA-124, PVA-117H, PVA-135H, PVA-HC, PVA-617, PVA-624, PVA-706, PVA-613, PVA-CS, PVA-CST, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Of Gohsenol NL-05, NM-11, NM-14, AL-06, P-610, C-500, A-300, AH-17, JF-04, JF manufactured by Nihon Ventures & Poval Co., Ltd. -05, JF-10, JF-17, JF-17L, JM-05, JM-10, JM-17, JM-17L, JT-05, JT-13, JT- 5, and the like.

Furthermore, preferable water-soluble polymers used for the protective layer include, for example, itaconic acid and maleic acid-modified carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol and the like, and these acid-modified polyvinyl alcohols are also more preferable. It can be preferably used.
Examples of the acid-modified polyvinyl alcohol that can be suitably used for forming the protective layer include, for example, KL-118, KM-618, KM-118, SK-5102, MP-102, R-2105, manufactured by Kuraray Co., Ltd. GOHSENAL CKS-50, T-HS-1, T-215, T-350, T-330, T-330H, manufactured by Chemical Industry Co., Ltd. 17 etc. are mentioned.

The water-soluble polymer (preferably polyvinyl alcohol) is preferably contained in the range of 45 to 95% by mass and contained in the range of 50 to 90% by mass with respect to the total solid content in the protective layer. More preferred. In the range of this content, excellent film-forming properties, high sensitivity and low adhesiveness resulting therefrom are achieved, and the effect of suppressing adhesion between laminated lithographic printing plate precursors is exhibited.
Only 1 type may be used for the water-soluble polymer which forms a protective layer, and multiple types may be used together according to the objective. For example, oxygen permeability can be controlled by using polyvinylpyrrolidone in combination with PVA. Even when a plurality of types of water-soluble polymers are used, the total content thereof is preferably in the above mass range.

The coating amount of polyvinyl alcohol in the protective layer is selected in consideration of oxygen barrier properties / development removal properties, fogging properties, adhesion properties, and scratch resistance.
The protective layer preferably has an oxygen permeability at 25 ° C.-60% RH 1 atm of 0.5 ml / m ² · day to 100 ml / m ² · day, and a composition that achieves this oxygen permeability is selected. .

(Preparation of protective layer forming coating solution)
In the formation of the protective layer, the silica-coated fine particles and optionally used organic resin fine particles are supplied in powder form directly in an aqueous solution of a water-soluble polymer such as polyvinyl alcohol, which is the main component of the protective layer. What is necessary is just to add and disperse | distribute. As a dispersion method, for example, a dispersion method using a known simple disperser such as a homogenizer, a homomixer, a ball mill, or a paint shaker may be used.

At this time, a surfactant can be added as desired for the purpose of improving dispersion stability. As the surfactant used for improving the dispersion stability, any of a nonionic surfactant, an anionic surfactant, and a cationic surfactant can be used.
Examples of nonionic surfactants include polyethylene glycol alkyl ethers, alkenyl ethers, polyethylene glycol alkyl esters, polyethylene glycol aryl ethers, and the like. Anionic surfactants include alkyl or aryl sulfonate type, alkyl or aryl sulfate ester type, alkyl or aryl phosphate ester type, alkyl or aryl carboxylate type surfactants. Examples of the cationic surfactant include alkylamine salt type, alkylpyridinium salt type, and alkylammonium salt type surfactants.
More specifically, more specific examples of these surfactants are described in “Latest Surfactant Functional Creation / Material Development / Applied Technology” Teruo Horiuchi, edited by Toshiyuki Suzuki Can be mentioned.

  Moreover, when using Mitsui Chemicals Chemie Pal series fine particles as silica-coated fine particles, since these fine particles are supplied in a state of being dispersed in water, these dispersions are directly added and stirred in the protective layer aqueous solution, A protective layer coating solution can be prepared.

In addition to the above-described components, various additives can be added to the protective layer depending on the purpose within a range not impairing the effects of the present invention.
For example, a colorant (water-soluble dye) that is excellent in the transmittance of light (infrared light in the present invention) used for exposing an image recording layer and can efficiently absorb light having a wavelength that is not related to exposure. May be added. Thereby, safelight aptitude can be improved, without reducing a sensitivity.

[Layer structure of protective layer]
The protective layer may have a single layer structure or a laminated structure having a plurality of layers. In the case of having a plurality of layers, the uppermost layer needs to contain silica-coated fine particles.

(Mica compound)
In the protective layer, it is preferable to use a mica compound from the viewpoint of improving oxygen barrier properties. When the mica compound is used in combination, the mica compound may be contained in any one of the layers constituting the protective layer.
For example, in the case of having only a specific protective layer having a single layer structure, this is the uppermost layer. Therefore, in addition to the water-soluble polymer and silica-coated fine particles, a mica compound may be added to the protective layer. In this case, the uppermost layer contains a water-soluble polymer and silica-coated fine particles, but even if the mica compound is contained in the uppermost layer, it is a binder, preferably water-soluble, in the other layers near the recording layer. It may be included with the polymer.

The mica compound used in the protective layer is, for example, a general formula: A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [where A is any of K, Na, and Ca , B and C are any one of Fe (II), Fe (III), Mn, Al, Mg and V, and D is Si or Al. ] Mica groups such as natural mica and synthetic mica represented by

Examples of the mica compound that can be used for the protective layer include muscovite, soda mica, phlogopite, biotite, and micaceous mica. Examples of synthetic mica include non-swellable mica such as fluor-phlogopite mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 (Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li Teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , Montmorillonite Na or Li Hectorite (Na, Li) _1/8 Mg _2/5 Li ₁ Swellable mica such as _{/ 8} (Si ₄ O ₁₀ ) F ₂ . In addition, synthetic smectites are also useful.

Of the mica compounds, fluorine-based swellable mica is particularly useful. That is, this swellable synthetic mica has a laminated structure composed of unit crystal lattice layers with a thickness of about 100 to 150 nm (10 to 15 cm), and the substitution of metal atoms in the lattice is significantly larger than other viscosity minerals. As a result, the lattice layer is deficient in positive charges, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers in order to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , since the ionic radius is small, the bond between the layered crystal lattices is weak, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Swellable synthetic mica has a strong tendency and is useful in the present invention. In particular, swellable synthetic mica is preferably used from the viewpoint that particles of uniform quality are easily available.

  As the shape of the mica compound, it has a plate-like particle shape, and from the viewpoint of adsorption to the organic resin fine particles, the smaller the thickness, the better the plane size. As long as it does not impair the permeability, the larger the better. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured from, for example, a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  The average major axis of the mica compound used in the protective layer is 0.3 to 20 μm, preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. Specifically, for example, the swellable synthetic mica that is a representative compound has a thickness of 1 to 50 nm and a surface size (major axis) of about 1 to 20 μm.

When the mica compound is contained in the same layer as the silica-coated fine particles, the amount contained in the protective layer of the mica compound varies depending on the addition amount and type of the silica-coated fine particles. The weight ratio of mica particles to weight is preferably in the range of 3: 1 to 2: 3, more preferably in the range of 2: 1 to 1: 1.
In the above-mentioned range, the silica-coated fine particles can achieve both the effect of improving dispersibility and the improvement of scratch resistance when rubbing with the back surface of the Al support. Even when a plurality of types of mica compounds are used in combination, the total amount of these mica compounds needs to be the above weight ratio.
In the case of a protective layer having a laminated structure, a mica compound may be used in any of a plurality of layers. However, when the layer is a layer that does not contain silica-coated fine particles, Thus, it is preferable to add the mica compound at a ratio of 5 to 50 parts by mass.

(Formation of protective layer)
The protective layer stirs and mixes a dispersion in which silica-coated fine particles are dispersed and a dispersion in which a mica compound used in combination is dispersed as desired, and the dispersion and a binder component containing polyvinyl alcohol (or polyvinyl alcohol). And an aqueous solution in which a binder component is dissolved) is added to the image recording layer. It should be noted that the blending order of the silica-coated fine particles, the mica compound and the hydrophilic polymer during the preparation of the protective layer coating solution can be appropriately changed according to the purpose. Specifically, for example, as described above, the particle component supplied as a powder can be directly added and dispersed in the hydrophilic polymer solution. Further, other particles used in combination with the particle dispersion prepared in advance can be directly added and dispersed.
In addition, when the protective layer has a plurality of layer structures and the mica compound is added to a layer that is closer to the recording layer than the uppermost layer, silica-coated fine particles are added to the layer. Since it is not necessary, the uppermost protective layer coating solution is prepared as described, and the layer containing the mica compound may be formed using a coating solution in which the mica compound is dispersed by the method described in detail below. .

An example of a general dispersion method of the mica compound used for the protective layer will be described. First, 5 to 10 parts by mass of the swellable mica compound mentioned above as a preferable mica compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen, and then dispersed by a disperser.
Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used.
A dispersion of 2 to 15% by mass of the mica compound dispersed by the above method is highly viscous or gelled, and the storage stability is very good. When preparing a coating solution for a protective layer using this dispersion, when used in combination with silica-coated fine particles or organic resin fine particles, these aqueous dispersions are mixed and sufficiently stirred, and then contain polyvinyl alcohol. It is preferably prepared by blending with a binder component (or an aqueous solution in which a binder component containing a specific polyvinyl alcohol is dissolved). In the case where the same layer does not coexist with silica-coated fine particles, the dispersion and the binder component may be blended and prepared.

  Known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the coating solution for the protective layer. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion to the recording layer and the temporal stability of the coating solution may be added to the coating solution.

  The method for applying the protective layer is not particularly limited, and a method described in US Pat. No. 3,458,311 or JP-A-55-49729 can be applied.

Coating amount of the protective layer, when the protective layer having a single layer structure, it is ^{preferably, 0.3g / m 2 ~3.0g / m} 2 is 0.1g / m ² ~4.0g / m ² More preferably. In the range of this coating amount, the film strength of the protective layer is maintained well, and scratch resistance is excellent. Moreover, since the permeability and oxygen barrier property of light incident on the protective layer by exposure are maintained in an appropriate range, there is no concern that image quality deteriorates or safelight suitability deteriorates.
If the protective layer has a laminated structure, the coating amount of the uppermost layer containing silica-coated fine particles is preferably from ^{0.1g / m 2 ~3.0g / m 2} , 0.5g / m 2 ~2. More preferably, it is 0 g / m ² . Preferably the coating amount of the protective layer is 0.1g / m ² ~2.0g / m ² provided between the uppermost and the recording layer, at 0.2g / m ² ~1.0g / m ² More preferably it is.
When the protective layer has a laminated structure, the layer provided between the uppermost layer and the image recording layer contains a water-soluble polymer having excellent oxygen barrier properties and a mica compound. It is preferable from the viewpoint of coexistence.

(Back treatment of aluminum support)
The lithographic printing plate precursor according to the invention is preferably modified on the back surface of the aluminum support for the purpose of further improving scratch resistance. Examples of the method for modifying the back surface of the aluminum support include a method of uniformly forming an anodized film on the entire back surface of the aluminum support in the same manner as the recording layer side, and a method of forming a backcoat layer. . The film-forming amount in the case of taking a method of forming an anodic oxide film, is preferably 0.6 g / m ² or more, preferably in the range of 0.7~6g / m ^2. Of these, a method of providing a backcoat layer is more effective and preferable. Hereinafter, these back surface processing methods will be described.

(1. Method for forming back surface anodized film)
First, a method for uniformly forming an anodic oxide film of 0.6 g / m ² or more on the entire back surface of the aluminum support in the same manner as the image recording layer side will be described. The formation of the anodized film is performed by the same means as described in the surface treatment of the aluminum support. The thickness of the anodized film provided on the back surface of the support is effective if it is 0.6 g / m ² or more, and the upper limit is not particularly limited from the viewpoint of performance. Considering energy, time required for formation, etc., it may be about 6 g / m ² , and a practical preferable film amount is 0.7 g to 6 g / m ² , and a more preferable range is 1.0 g to 3 g / m ^2. m ² .
The amount of the anodic oxide film can be converted by measuring the peak of Al ₂ O ₃ using fluorescent X-rays and using a calibration curve of the peak height and the film amount.

An anodic oxide film is provided on the entire surface of the aluminum support, and the amount thereof is 0.6 g / m ² or more. This means that the anodic oxide film on the side opposite to the image recording layer of the aluminum support in the lithographic printing plate precursor is used. The amount of the anodic oxide film is 0.6 g / m ² for each of the center part of the surface and the end part 5 cm from both ends in the direction (Transverse Direction) that passes through the center part and is orthogonal to the processing direction (Machine Direction). This is confirmed by the above.

(2. Method for forming backcoat layer)
Next, a method for providing a backcoat layer on the back surface of the aluminum support will be described. As the back coat layer, any composition may be used, and in particular, a metal oxide obtained by hydrolysis and polycondensation of an organic metal compound or an inorganic metal compound described in detail below, and a colloidal silica sol. And a backcoat layer comprising an organic resin film is preferred.
(2-1. Backcoat layer containing metal oxide and colloidal silica sol)
A preferred first aspect of the backcoat layer is a backcoat layer containing a metal oxide and a colloidal silica sol.
More specifically, it is formed by a so-called sol-gel reaction solution in which an organometallic compound or an inorganic metal compound is hydrolyzed with a catalyst such as an acid or alkali in a water and an organic solvent, and a polycondensation reaction is caused. A backcoat layer is preferred.
Examples of the organic metal compound or inorganic metal compound used for forming the back coat layer include metal alkoxide, metal acetylacetonate, metal acetate, metal oxalate, metal nitrate, metal sulfate, metal carbonate, metal oxychloride. , Metal chlorides, and condensates obtained by oligomerizing these by partial hydrolysis.
The metal alkoxide is represented by a general formula of M (OR) _n (M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element). Specific examples include, for example, Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ , Al (OCH ₃ ) ₃ , Al ( _{OC 2 H 5) 3, Al} (OC 3 H 7) 3, Al (OC 4 H 9) 3, B (OCH 3) 3, B (OC 2 H 5) 3, B (OC 3 H 7) 3, B (OC ₄ H ₉ ) ₃ , Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₃ H ₇ ) ₄ , Ti (OC ₄ H ₉ ) ₄ , Zr (OCH ₃ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC ₃ H ₇ ) ₄ , Zr (OC ₄ H ₉ ) _{4 and the} like can be mentioned. For example, Ge, Li, Na, Fe, Ga, Mg, P , Alkoxides of atoms such as Sb, Sn, Ta, and V. In addition, mono-substituted silicon such as CH ₃ Si (OCH ₃ ) ₃ , C ₂ H ₅ Si (OCH ₃ ) ₃ , CH ₃ Si (OC ₂ H ₅ ) ₃ , C ₂ H ₅ Si (OCC ₂ H ₅ ) ₃ Alkoxides are also used.

These organic metal compounds or inorganic metal compounds can be used alone or in combination of two or more. Among these organometallic compounds or inorganic metal compounds, metal alkoxides are preferable because they are highly reactive and easily form a polymer made of a metal-oxygen bond. Among them, silicon alkoxide compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are inexpensive and easily available. The coating layer of the metal oxide obtained therefrom is excellent and particularly preferred. Also preferred are oligomers obtained by condensing these silicon alkoxide compounds by partial hydrolysis. An example of this is an average pentameric ethylsilicate oligomer containing about 40% by weight of SiO ₂ .

Furthermore, it is also preferable to use a so-called silane coupling agent in which one or two alkoxy groups of the silicon tetraalkoxy compound are substituted with an alkyl group or a reactive group in combination with these metal alkoxides. As the silane coupling agent to be added to the backcoat layer in the present invention, one or two alkoxy groups in the silicon tetraalkoxy compound may be a hydrophobic group such as a long-chain alkyl group having 4 to 20 carbon atoms or a fluorine-substituted alkyl group. Examples include silane coupling agents substituted with a substituent, and silane coupling agents having a fluorine-substituted alkyl group are particularly preferable. Specific examples of such silane coupling _{agents, CF 3 CH 2 CH 2 Si} (OCH 3) 3, CF 3 CF 2 CH 2 CH 2 Si (OCH 3) 3, CF 3 CH 2 CH 2 Si (OC ₂ H ₅ ) _{3 and the} like, and commercially available products include LS-1090 manufactured by Shin-Etsu Chemical Co., Ltd. The preferable content of such a silane coupling agent is 5 to 90% by mass, more preferably 10 to 80% by mass, based on the total solid content of the backcoat layer.

  As a catalyst useful when forming a sol-gel coating solution for the backcoat layer, organic and inorganic acids and alkalis are used. Examples include hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, hydrofluoric acid, phosphoric acid, phosphorous acid and other inorganic acids, formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, chloroacetic acid, dichloroacetic acid, Trichloroacetic acid, fluoroacetic acid, bromoacetic acid, methoxyacetic acid, oxaloacetic acid, citric acid, oxalic acid, succinic acid, malic acid, tartaric acid, fumaric acid, maleic acid, malonic acid, ascorbic acid, benzoic acid, 3,4-dimethoxybenzoic acid Substituted benzoic acids such as acids, phenoxyacetic acid, phthalic acid, picric acid, nicotinic acid, picolinic acid, pyrazine, pyrazole, dipicolinic acid, adipic acid, p-toluic acid, terephthalic acid, 1,4-cyclohexene-2,2 -Organic acids such as dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and hydroxy acids of alkali metals and alkaline earth metals Things, ammonia, ethanolamine, diethanolamine, and alkali such as triethanolamine.

  Other preferred catalysts include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, and phosphate esters, such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl acid. Organic acids such as phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, and diphenyl phosphate can also be used.

  These catalysts can be used alone or in combination of two or more. The catalyst is preferably from 0.001 to 10% by mass, more preferably from 0.05 to 5% by mass, based on the starting metal compound. If the amount of the catalyst is less than this range, the start of the sol-gel reaction is delayed, and if it is more than this range, the reaction proceeds rapidly and non-uniform sol-gel particles are formed. Become.

  In order to initiate the sol-gel reaction, an appropriate amount of water is further required, and the preferred amount of addition is preferably 0.05 to 50 times the amount of water required to completely hydrolyze the starting metal compound. More preferably, it is 0.5 to 30 times mol. If the amount of water is less than this range, the hydrolysis is difficult to proceed, and if it is more than this range, the reaction is difficult to proceed because the raw material is diluted.

A solvent is further added to the sol-gel reaction solution. Any solvent may be used as long as it dissolves the starting metal compound and dissolves or disperses the sol-gel particles produced by the reaction, such as lower alcohols such as methanol, ethanol, propanol, and butanol, acetone, methyl ethyl ketone, diethyl ketone, and the like. Ketones are used. In addition, mono- or dialkyl ethers and acetates of glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol can be used for the purpose of improving the coating surface quality of the backcoat layer. Of these solvents, lower alcohols that are miscible with water are preferred. The sol-gel reaction solution is prepared with a solvent at a concentration suitable for coating. However, if the total amount of the solvent is added to the reaction solution from the beginning, the raw material is diluted, making it difficult for the hydrolysis reaction to proceed. Therefore, a method of adding a part of the solvent to the sol-gel reaction solution and adding the remaining solvent when the reaction proceeds is preferable.
The coating amount of the back coat layer containing the metal oxide thus formed and the colloidal silica sol is preferably 0.01 to 3.0 g / m ^{2 and} preferably 0.03 to 1.0 g / m ^2. More preferably.

(2-2. Backcoat layer made of organic resin film)
As another preferred example of the back coat layer, a back coat layer composed of an organic resin film formed on the back surface of the support can be mentioned.
Preferable resins that can form the backcoat layer include thermosetting resins such as urea resins, epoxy resins, phenol resins, melamine resins, and diallyl phthalate resins. Among these, from the viewpoint that the physical strength of the layer to be formed is high, a phenol resin is preferable, and more specifically, for example, phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m− / p. Preferred examples include novolak resins and pyrogallol acetone resins such as mixed cresol formaldehyde resins and phenol / cresol (which may be either m-, p-, or m- / p-mixed) mixed formaldehyde resins.

Further, as the phenol resin, as described in US Pat. No. 4,123,279, an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is further used. Examples thereof include a condensation polymer of phenol and formaldehyde as a substituent.
The phenol resin preferably has a weight average molecular weight of 500 or more from the viewpoint of image forming properties, and more preferably 1,000 to 700,000. The number average molecular weight is preferably 500 or more, and more preferably 750 to 650,000. The dispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  Moreover, these phenol resins may be used alone or in combination of two or more. In the case of combination, it has 3 to 8 carbon atoms such as a condensation polymer of t-butylphenol and formaldehyde or a condensation polymer of octylphenol and formaldehyde as described in US Pat. No. 4,123,279. A polycondensation product of phenol and formaldehyde having an alkyl group as a substituent, an organic compound having a phenol structure having an electron-withdrawing group on an aromatic ring described in JP-A-2000-241972 previously filed by the present inventors You may use resin etc. together.

A surfactant can be added to the backcoat layer for the purpose of improving the coating surface properties and controlling the surface properties. The surfactant used here is an anionic surfactant having any of carboxylic acid, sulfonic acid, sulfate ester and phosphate ester; a cationic surfactant such as aliphatic amine, quaternary ammonium salt. Agents: Betaine-type amphoteric surfactants; or nonionic surfactants such as fatty acid esters of polyoxy compounds, polyalkynelene oxide condensation type, polyethyleneimine condensation type, and fluorine surfactants. A fluorochemical surfactant is preferred.
The addition amount of the surfactant is appropriately selected according to the purpose, but in general, it can be added in the range of 0.1 to 10.0% by mass in the back coat layer.

As the fluorine-based surfactant, a fluorine-based surfactant containing a perfluoroalkyl group in the molecule is particularly preferable. Such a fluorinated surfactant will be described in detail.
Fluorosurfactants that can be particularly preferably used in the backcoat layer include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates, and amphoteric such as perfluoroalkyl betaines. Type, cationic type such as perfluoroalkyltrimethylammonium salt and perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, perfluoroalkyl group and hydrophilic group-containing oligomer, perfluoroalkyl group and lipophilic group-containing oligomer, perfluoro Nonionic types such as alkyl group, hydrophilic group and lipophilic group-containing oligomer, perfluoroalkyl group and lipophilic group-containing urethane are included. Among these, the fluoroaliphatic group is preferably a group represented by the following general formula (1).

(In the general formula (1), R ² and R ³ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X is selected from a single bond, an alkylene group, an arylene group, or the like. Represents a divalent linking group, m represents an integer of 0 or more, and n represents an integer of 1 or more.)
Here, when X represents a divalent linking group, the linking group such as an alkylene group or an arylene group may have a substituent, and the structure includes an ether group, an ester group, an amide group. It may have a linking group selected from a group and the like. Examples of the substituent that can be introduced into the alkylene group or arylene group include a halogen atom, a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an alkyl group, and an aryl group, and these may further have a substituent. Good. Among these, X is preferably an alkylene group, an arylene group, or an alkylene group having a linking group selected from an ether group, an ester group, an amide group, and the like, an unsubstituted alkylene group, an unsubstituted arylene group, or An alkylene group having an ether group or an ester group inside is more preferable, and an unsubstituted alkylene group or an alkylene group having an ether group or an ester group inside is most preferable.
It is preferable to contain about 0.5 to 10% by mass of such a fluorosurfactant in the backcoat layer.

  Various methods can be applied to cover the back surface of the aluminum support with the backcoat layer made of an organic resin film. After adding fine particles such as silica gel to the backcoat layer components, specifically, organic resin as the main ingredient, if desired, for example, dissolved in an appropriate solvent or prepared as an emulsified dispersion to prepare a coating solution Then, it is applied to the back side of the support and dried, or an organic resin film previously formed into a film shape is attached to the aluminum support via an adhesive or by heating, and a molten film is formed with a melt extruder. And a method of bonding to a support. Among these, the most preferable method from the viewpoint of easy control of the coating amount is a method of coating and drying the solution. As the solvent used here, an organic solvent as described in JP-A-62-251739 is used alone or in combination.

  Examples of the means for applying the backcoat layer coating solution on the surface of the aluminum support include known metering application devices such as a bar coater, a roll coater, a gravure coater, a curtain coater, an extruder, and a slide hopper. A non-contact type quantitative coater such as a curtain coater, an extruder or a slide hopper is particularly preferred because it does not damage the back surface.

The thickness of the back coat layer is such that the formed film thickness is in the range of 0.1 to 8 μm in both the back coat layer containing the metal oxide and the colloidal silica sol and the back coat layer made of an organic resin. preferable. Within this thickness range, the surface slipperiness of the back surface of the aluminum support is improved, and during printing, the thickness variation due to dissolution and swelling of the backcoat layer by chemicals used around the printing, and the printing pressure resulting therefrom Can suppress the deterioration of the printing characteristics due to the change.
In the back coat layer, the most preferable is a back coat layer made of an organic resin.

[Preparation of lithographic printing plate precursor]
The lithographic printing plate precursor is provided with an image recording layer on an aluminum support, and further provided with a protective layer and an undercoat layer, if necessary. Such a lithographic printing plate precursor can be produced by dissolving the above-described coating liquids containing the various components in an appropriate solvent and sequentially coating the solution on an aluminum support.

When coating the image recording layer, the components of the image recording layer are dissolved in various organic solvents to form an image recording layer coating solution, which is applied onto the aluminum support or the undercoat layer.
Solvents used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol, diethylene glycol monomethyl Ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, Examples include ethyl lactate. These solvents can be used alone or in combination. The solid content in the image recording layer coating solution is suitably 2 to 50% by mass.

The coating amount of the image recording layer mainly affects the sensitivity, developability, exposure film strength and printing durability of the image recording layer, and is preferably selected as appropriate according to the application. When the coating amount is too small, the printing durability is not sufficient. On the other hand, if the amount is too large, the sensitivity is lowered, it takes time for exposure, and a longer time is required for development processing, which is not preferable. For the lithographic printing plate precursor for scanning exposure, the coating amount is suitably in the range of about 0.1 g / m ² to about 10 g / m ² in terms of the mass after drying. More preferably from 0.5 to 5 g / m ^2.

[Intermediate layer (undercoat layer)]
The lithographic printing plate precursor may be provided with an intermediate layer (undercoat layer) for the purpose of improving the adhesion and soiling between the image recording layer and the aluminum support. Specific examples of such an intermediate layer include JP-B-50-7481, JP-A-54-72104, JP-A-59-101651, JP-A-60-149491, JP-A-60-232998, JP-A-3-56177, JP-A-4-282737, JP-A-5-16558, JP-A-5-246171, JP-A-7-159983, JP-A-7-314937, JP-A-8-202025, Special Kaihei 8-320551, JP 9-34104, JP 9-236911, JP 9-269593, JP 10-69092, JP 10-115931, JP 10-161317, JP 10-260536, JP-A-10-282682, JP-A-11-84684, JP-A-11-38635, JP-A-11-38629, JP-A-10-282645, JP-A-10-301262, JP-A-11-24277, JP-A-11-109641, JP-A-10-319600, JP-A-11-84684, JP-A-11-327152, JP-A-11-327152 Examples thereof include those described in JP 2000-10292, JP 2000-235254, JP 2000-352854, JP 2001-209170, and Japanese Patent Application No. 11-284091.

<Plate making method>
Hereinafter, an example of a plate making method of a lithographic printing plate precursor will be described.
A plate making method of a lithographic printing plate precursor is a laminate comprising a plurality of the above-described lithographic printing plate precursors laminated (preferably, a protective layer is formed on the image recording layer, the protective layer and the back surface of the aluminum support, After the lithographic printing plate precursor is automatically conveyed one by one, it is exposed at a wavelength of 750 nm to 1400 nm, and then substantially heated. It is preferable to carry out development processing under conditions where the conveying speed is 1.25 m / min or more without undergoing processing.
Even if the above-described planographic printing plate precursor is laminated without interposing the interleaving paper in between, the adhesion between the planographic printing plate precursors and the generation of scratches on the protective layer are suppressed. Can be applied to the method.
According to the plate making method of the above-described planographic printing plate, since the laminate obtained by laminating the planographic printing plate precursor without sandwiching the slip sheet is used, it is not necessary to remove the slip sheet, and the productivity in the plate making process is improved. .

The light source used for the exposure process may be any light source that can be exposed at a wavelength of 750 nm to 1400 nm, but an infrared laser is preferable. In particular, in the present invention, image exposure is preferably performed using a solid-state laser and a semiconductor laser that emit infrared rays having a wavelength of 750 nm to 1400 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The energy applied to the planographic printing plate precursor is preferably 10 to 300 mJ / cm ² . If the exposure energy is too low, curing of the image recording layer does not proceed sufficiently in the case of a thermal negative type image recording layer. Further, in the case of a thermal positive type image recording layer, the interaction that lowers the alkali solubility of the alkali-soluble polymer compound is not sufficiently released. Also, if the exposure energy is too high, the recording layer may be laser ablated and the image may be damaged.

  In the exposure process, exposure can be performed by overlapping the light beams of the light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

  The light source scanning method of the exposure apparatus is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, and the like can be used. The channel of the light source may be a single channel or a multi-channel, but the multi-channel is preferably used in the case of a cylindrical outer surface type.

  In the present invention, as described above, the exposed lithographic printing plate precursor is subjected to a development process without performing any special heat treatment and water washing treatment. By not performing this heat treatment, image non-uniformity due to the heat treatment can be suppressed. In addition, by performing neither heat treatment nor water washing treatment, stable high-speed processing is possible in development processing.

〔developing〕
In the development process, a non-image portion of the image recording layer is removed using a developer.
In the present invention, as described above, the processing speed in the development process, that is, the transport speed (line speed) of the lithographic printing plate precursor in the development process is preferably 1.25 m / min or more, and more preferably. Is 1.35 m / min or more. Moreover, there is no restriction | limiting in particular in the upper limit of a conveyance speed, However, From a viewpoint of stability of conveyance, it is preferable that it is 3 m / min or less.
Hereinafter, the developer used in the present invention will be described.

(Developer)
The developer used in the present invention is preferably an alkaline aqueous solution having a pH of 14 or less, and preferably contains an aromatic anionic surfactant.

(Aromatic anionic surfactant)
The aromatic anionic surfactant used in the developer has a development accelerating effect and a dispersion stabilizing effect in the developer of the polymerizable negative recording layer component and the protective layer component, and is preferable in stabilizing the development process. Among them, the aromatic anionic surfactant is preferably a compound represented by the following general formula (A) or general formula (B).

In the above general formula (A) or general formula (B), R ¹ and R ³ each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, specifically an ethylene group. , Propylene group, butylene group, pentylene group, and the like, among which ethylene group and propylene group are particularly preferable.
m and n each independently represent an integer selected from 1 to 100. Among them, 1 to 30 are preferable, and 2 to 20 are more preferable. When m is 2 or more, a plurality of R ¹ may be the same or different. Similarly, when n is 2 or more, a plurality of R ³ may be the same or different.
t and u each independently represents 0 or 1.

R ² and R ⁴ each independently represent a linear or branched alkyl group having 1 to 20 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, hexyl group, dodecyl group Among them, a methyl group, an ethyl group, an iso-propyl group, an n-propyl group, an n-butyl group, an iso-butyl group, and a tert-butyl group are particularly preferable.
p and q each represent an integer selected from 0 to 2; Y ¹ and Y ² each represent a single bond or an alkylene group having 1 to 10 carbon atoms. Specifically, a single bond, a methylene group or an ethylene group is preferred, and a single bond is particularly preferred.
(Z ¹ ) ^{r +} and (Z ² ) ^{s +} each independently represents an alkali metal ion, an alkaline earth metal ion, or an ammonium ion that is unsubstituted or substituted with an alkyl group. Sodium ion, potassium ion, magnesium ion, calcium ion, ammonium ion, secondary to quaternary ammonium ion substituted with an alkyl group, aryl group, or aralkyl group in the range of 1 to 20 carbon atoms, etc. In particular, sodium ion is preferable. r and s each represent 1 or 2.
Specific examples are shown below, but the present invention is not limited thereto.

  These aromatic anionic surfactants may be used alone or in appropriate combination of two or more. The amount of the aromatic anionic surfactant added is preferably such that the concentration of the aromatic anionic surfactant in the developer is in the range of 1.0 to 10% by mass, more preferably in the range of 2 to 10% by mass. It is effective to do. Here, when the content is 1.0% by mass or less, the developability and the solubility of the image recording layer components are lowered, and when the content is 10% by mass or more, the printing durability of the lithographic printing plate is reduced. Reduce.

In addition to the aromatic anionic surfactant, other surfactants may be used in combination with the developer. Examples of other surfactants include polyoxyethylene naphthyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene stearyl ether, Polyoxyethylene alkyl esters such as oxyethylene stearate, sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan alkyl esters, glycerol mono Nonionic surfactants such as monoglyceride alkyl esters such as stearate and glycerol monooleate.
The content of these other surfactants in the developer is preferably from 0.1 to 10% by mass in terms of active ingredients.

(Chelating agent for divalent metals)
For example, the developer preferably contains a chelating agent for a divalent metal in order to suppress the influence of calcium ions contained in hard water. Examples of the chelating agent for the divalent metal include Na ₂ P ₂ O ₇ , Na ₅ P ₃ O ₃ , Na ₃ P ₃ O ₉ , Na ₂ O ₄ P (NaO ₃ P) PO ₃ Na ₂ , Calgon (polymetaline). Polyphosphates such as ethylenediaminetetraacetic acid, its potassium salt, its sodium salt, its amine salt; diethylenetriaminepentaacetic acid, its potassium salt, sodium salt; triethylenetetraminehexaacetic acid, its potassium salt, its sodium salt Hydroxyethylethylenediaminetriacetic acid, its potassium salt, its sodium salt; nitrilotriacetic acid, its potassium salt, its sodium salt; 1,2-diaminocyclohexanetetraacetic acid, its potassium salt, its sodium salt; 1,3-diamino-2 -Propanol tetraacetic acid, its potassium salt, 2-phosphonobutanetricarboxylic acid-1,2,4, potassium salt thereof, sodium salt thereof; 2-phosphonobutanone tricarboxylic acid-2,3,4, 1-phosphonoethanetricarboxylic acid-1,2,2, potassium salt, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri And organic phosphonic acids such as (methylenephosphonic acid), its potassium salt, its sodium salt, etc. Among them, ethylenediaminetetraacetic acid, its potassium salt, its sodium salt, its amine salt; ethylenediaminetetra (methylenephosphonic acid) ), Its ammonium salt, its potassium salt; hexamethyl Down diamine tetra (methylene phosphonic acid), an ammonium salt, its potassium salt is preferred.
The optimum amount of such a chelating agent varies depending on the hardness of the hard water used and the amount used, but is generally 0.01 to 5% by mass, more preferably 0% in the developing solution at the time of use. It is made to contain in the range of 0.01-0.5 mass%.

  Further, an alkali metal salt of an organic acid or an alkali metal salt of an inorganic acid may be added to the developer as a development regulator. For example, sodium carbonate, potassium, ammonium, sodium citrate, potassium, ammonium and the like may be used alone or in combination of two or more.

(Alkaline agent)
Examples of the alkali agent used in the developer include inorganic alkalis such as trisodium phosphate, potassium, ammonium, sodium borate, potassium, ammonium, sodium hydroxide, potassium, ammonium, and lithium. Agent, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanol Examples include organic alkali agents such as noramine, ethyleneimine, ethylenediamine, pyridine, and tetramethylammonium hydroxide. In the present invention, these may be used alone or in combination of two or more.

  Moreover, alkali silicate can be mentioned as alkali agents other than the above. Alkali silicates may be used in combination with a base. The alkali silicate to be used exhibits alkalinity when dissolved in water, and examples thereof include sodium silicate, potassium silicate, lithium silicate, and ammonium silicate. These alkali silicates may be used alone or in combination of two or more.

The developer is a mixture ratio of silicon oxide SiO ₂ which is a silicate component as a hydrophilic component of an aluminum support and alkali oxide M ₂ O (M represents an alkali metal or ammonium group) as an alkali component. And by adjusting the concentration, it can be easily adjusted to the optimum range. The mixing ratio of silicon oxide SiO ₂ and alkali oxide M ₂ O (molar ratio of SiO ₂ / M ₂ O) is left as a result of excessive dissolution (etching) of the anodized film of the aluminum support. From the viewpoint of suppressing the generation of insoluble gas due to complex formation between dissolved aluminum and silicate, it is preferably in the range of 0.75 to 4.0, more preferably 0.75 to 3.5. Used in range.

The concentration of the alkali silicate in the developer includes the dissolution (etching) suppression effect of the anodized film on the aluminum support, the developability, the suppression effect of precipitation and crystal formation, and the gel during neutralization during the waste liquid. From the standpoint of the anti-oxidation effect, etc., the amount of SiO ₂ is preferably 0.01 to 1 mol / L, more preferably 0.05 to 0.8 mol / L with respect to the mass of the developer.

  In the developer, in addition to the above components, the following components may be used in combination as required. For example, benzoic acid, phthalic acid, p-ethylbenzoic acid, pn-propylbenzoic acid, p-isopropylbenzoic acid, pn-butylbenzoic acid, pt-butylbenzoic acid, pt-butylbenzoic acid Acids, p-2-hydroxyethylbenzoic acid, decanoic acid, salicylic acid, organic carboxylic acids such as 3-hydroxy-2-naphthoic acid; organic solvents such as propylene glycol; other reducing agents, dyes, pigments, water softeners And preservatives.

  The developer preferably has a pH in the range of 10 to 12.5 at 25 ° C, and more preferably in the range of pH 11 to 12.5. Since the developer in the present invention contains the surfactant, even if such a low pH developer is used, excellent developability is exhibited in the non-image area. Thus, by setting the pH of the developing solution to a relatively low value, damage to the image area during development is reduced and the handling property of the developing solution is excellent.

The conductivity x of the developer is preferably 2 <x <30 mS / cm, more preferably 5 to 25 mS / cm.
Here, it is preferable to add an alkali metal salt of an organic acid, an alkali metal salt of an inorganic acid, or the like as a conductivity adjusting agent for adjusting the conductivity.

  The developer can be used as a developer and a development replenisher for the exposed lithographic printing plate precursor, and is preferably applied to an automatic processor. When developing using an automatic developing machine, the developing solution becomes fatigued according to the amount of processing, so that the processing capability may be restored by using a replenishing solution or a fresh developing solution. This replenishment method is also preferably applied to the plate making method of the present invention.

  Furthermore, in order to restore the processing capacity of the developer using an automatic developing machine, it is preferable to replenish by the method described in US Pat. No. 4,882,246. Developers described in JP-A-50-26601, 58-54341, JP-B-56-39464, 56-42860, and 57-7427 are also preferable.

  A more preferable development replenisher contains an oxycarboxylic acid chelating agent having an ability to form a water-soluble chelate compound with aluminum ions, an alkali metal hydroxide, a surfactant, no silicate, and a pH of 11 A development replenisher characterized by being an aqueous solution of ˜13.5. By using such a development replenisher, it has excellent developability and characteristics that do not impair the strength of the image area of the plate material, and is formed by elution of the aluminum support by the alkali of the developer. Precipitation of aluminum is effectively suppressed, and adhesion of stains mainly composed of aluminum hydroxide to the surface of the developing bath roller of the automatic processor and subsequent accumulation of aluminum hydroxide precipitates in the washing bath are reduced. It can be processed stably for a long time.

  The lithographic printing plate precursor thus developed is subjected to washing water, surface activity as described in JP-A Nos. 54-8002, 55-11545, 59-58431, and the like. It is post-treated with a desensitizing solution containing a rinse solution containing an agent and the like, gum arabic and starch derivatives.

In the lithographic printing plate making method, for the purpose of improving the image strength and printing durability, the image after development can be subjected to full post-heating or full exposure.
Very strong conditions can be used for heating after development. Usually, the heating temperature is 200 to 500 ° C. If the heating temperature after development is low, sufficient image reinforcing action cannot be obtained, and if it is too high, problems such as deterioration of the aluminum support and thermal decomposition of the image area may occur.

The planographic printing plate obtained by the above processing is loaded on an offset printing machine and used for printing a large number of sheets.
As the plate cleaner used for removing stains on the plate during printing, a conventionally known plate cleaner for PS plate is used. For example, a multi cleaner, CL-1, CL-2, CP, CN-4, CN, CG-1, PC-1, SR, IC (made by Fuji Photo Film Co., Ltd.), etc. are mentioned.

Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. These examples show one preferred embodiment of the present invention, and the present invention is not limited thereto.

[Examples 1-1 to 1-20, Comparative Example 1-1]
Aluminum alloy whose composition is Fe: 0.30 wt%, Si: 0.09 wt%, Cu: 0.015 wt%, Ti: 0.03 wt%, Mg and Mn: the contents shown in Table 1, the balance being Al and inevitable impurities The cast surface of the resulting ingot is chamfered by 5 mm / single side to a thickness of 500 mm, and each ingot is homogenized (temperature: 540 ° C., 3 hours), hot rough rolling ( (Starting temperature: 455 ° C., end temperature: 460 ° C.), hot finish rolling was performed, and the coil was wound around a coil as an aluminum alloy plate having a thickness of 4.5 mm. The holding time after the end of hot rolling and before the start of hot rolling was 100 seconds, and the finish temperature of hot finish rolling was 345 ° C.
This aluminum alloy plate was further subjected to cold rolling treatment and flatness correction treatment, and finished to a plate thickness of 0.297 mm.
The average recrystallized grain size in the direction perpendicular to the rolling direction of the aluminum alloy sheet surface layer was 0.02 to 0.04 mm.
Moreover, the crystal length extended in the rolling direction of this aluminum alloy plate surface layer part was 0.55-0.85 mm on average.
The average recrystallized grain size and crystal length were measured by measuring the surface roughness of each aluminum alloy plate obtained with # 800 water-resistant abrasive paper (arithmetic average roughness (cut according to JIS B0601-1994) (Off value 0.8 mm, evaluation length 4 mm)) is finished to an extent of 0.2, and further buffed by about 1 to 1.5 μm using an alumina suspension (particle diameter 0.05 μm), then 10% About 0.5 to 1.0 μm of etching treatment was performed with a hydrofluoric acid aqueous solution. In this way, the crystal grain boundary can be observed, the crystal structure is photographed with a polarizing microscope, and the width of 20 crystal grains located in the surface layer portion from the surface of the aluminum alloy plate to a depth of 50 μm is measured. And the length were measured, and an average value and a maximum value were obtained.

  The aluminum alloy plate obtained by the above procedure was roughened by the following roughening method A or B to obtain an aluminum support for a lithographic printing plate.

Surface roughening method A
Various surface treatments of the following (a) to (j) were continuously performed on the aluminum alloy plate.
Hereinafter, each of the surface treatments (a) to (j) will be described.
(A) Mechanical roughening treatment (brush grain) <Mechanical roughening treatment>
A mechanical surface-roughening treatment with a rotating roller-shaped nylon brush while supplying an aqueous suspension (specific gravity 1.1 g / cm ³ ) of an abrasive (pumice, median diameter 25 μm) as an abrasive slurry to the surface of an aluminum plate Went.
The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 400 mm.
The number of rotations of the brush was adjusted so that the desired Ra was obtained.
(B) Alkali etching treatment <First etching treatment>
The alkali etching treatment was performed by spraying a caustic soda aqueous solution having a caustic soda concentration of 26 mass%, an aluminum ion concentration of 6.5 mass%, and a liquid temperature of 70 ° C. so that the aluminum dissolution amount was 10 g / m ² . Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(C) Desmut treatment <first desmut treatment>
The desmut treatment was performed by dipping in an aqueous solution of nitric acid 10 g / l, aluminum ions 5 g / l, and a liquid temperature of 35 ° C. for 10 seconds. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.

(D) Electrochemical surface roughening treatment (electrolytic surface roughening electrolysis in nitric acid aqueous solution) <First electrolytic surface roughening treatment>
Electrochemical roughening treatment was performed using an alternating current having a trapezoidal waveform with a frequency of 60 Hz. The electrolytic solution was nitric acid 10 g / l, aluminum ions 5 g / l, and the liquid temperature was 50 ° C. The trapezoidal AC power supply waveform used had a time TP of 0.8 msec and a duty of 0.5 until the current value reached a peak from zero, and the current density was 50 A / dm ² at the peak value of the current waveform.
The amount of electricity was 185 C / dm ^{2 as} the total amount of electricity when the aluminum plate was an anode. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(E) Alkali etching treatment <second etching treatment>
The alkali etching treatment is performed by spraying a caustic soda aqueous solution having a caustic soda concentration of 26 mass%, an aluminum ion concentration of 6.5 mass%, and a liquid temperature of 35 ° C. so that the aluminum dissolution amount is 0.2 g / m ^2. It was. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(F) Desmut processing <Second desmut processing>
The desmut treatment was performed by dipping in an aqueous solution of sulfuric acid 170 g / L and aluminum ions 7 g / l at 35 ° C. for 10 seconds. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.

(G) Electrochemical roughening treatment (electrolytic roughening treatment in aqueous hydrochloric acid) <Second electrolytic roughening treatment>
Electrochemical roughening treatment was performed using an alternating current having a trapezoidal waveform with a frequency of 60 Hz. The electrolytic solution was hydrochloric acid 7 g / l, aluminum ions 5 g / l, and the liquid temperature was 35 ° C. The trapezoidal AC power supply waveform used had a time TP of 0.8 msec and a duty of 0.5 until the current value reached a peak from zero, and the current density was 50 A / dm ² at the peak value of the current waveform.
The amount of electricity was 63 C / dm ^{2 as} the total amount of electricity when the aluminum plate was an anode. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(H) Alkali etching treatment <Third alkali etching treatment>
The alkali etching treatment is performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass and a liquid temperature of 35 ° C. so that the aluminum dissolution amount is 0.1 g / m ^2. It was. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(I) Desmut processing <Third desmut processing>
A desmut treatment was performed by dipping in an aqueous solution of sulfuric acid 170 g / L and aluminum ions 7 g / l at 35 ° C. for 10 seconds. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.
(J) Anodizing treatment <Anodizing treatment>
In an electrolytic solution of sulfuric acid 170 g / l, aluminum ions 7 g / l, and liquid temperature 50 ° C., using a direct current with a current density of 30 A / dm ² , the amount of anodic oxide film is 2.9 g / m ^2. Anodized. Thereafter, the liquid was drained with a nip roller, washed with water, and further drained with a nip roller.

Surface roughening method B
(A) Mechanical roughening treatment (brush grain), (g) Electrochemical roughening treatment (electrolytic roughening treatment in aqueous hydrochloric acid), (h) Alkali A roughening treatment was performed in the same manner as in the roughening method A, except that the etching treatment and (i) desmutting treatment were not performed.

  The center line average surface roughness (Ra) of the aluminum support was measured using a needle having a diameter of 2 μm by performing the roughening treatment by the roughening method A or B. The results are shown in Table 1. The desired surface roughness Ra was obtained by adjusting the number of rotations of the brush.

(I) Measurement of tensile strength and 0.2% proof stress Shimadzu Corporation based on JIS Z2241 (Metal Material Tensile Test Method) for aluminum support obtained by surface roughening by surface roughening method A or B Using an autograph (AGS-5KNH) manufactured, tensile strength and 0.2% proof stress were measured under the condition of tensile speed: 2 mm / min.
The obtained results are shown in Table 1.

(Ii) Measurement of the specific surface area of the aluminum support after the roughening treatment.
About the aluminum support obtained by roughening by the roughening method A or B, the following formula (from the actual area by the three-dimensional data measured using an atomic force microscope (AFM) ( The specific surface area ΔS calculated according to I) was determined. ΔS is a value calculated from the following formula (I) from three-dimensional data obtained by measuring 256 × 256 points with a 25 μm square using an atomic force microscope.
ΔS = (surface area determined by approximate three-point method−geometric area) / geometric area × 100 (%) Formula (I)
The atomic force microscope used for the measurement in the present invention is manufactured by Seiko Denshi Kogyo Co., Ltd., controller SPI-3000, the measuring device is SPA-400, and the measurement is performed by piezo an aluminum plate cut to a size of 1 cm square. Set on a horizontal sample stage on the scanner, approach the cantilever to the sample surface, and when it reaches the area where the atomic force works, scan in the XY direction, and at that time, catch the unevenness of the sample with the piezo displacement in the Z direction It was. The cantilever was OMCL-AC160TS-C2 manufactured by Olympus Corporation, having a resonance frequency of 300 kHz and a spring constant of 42 N / m, and was measured in a DFM mode (Dynamic Force 00). In addition, a slight slope of the sample was corrected by approximating the obtained three-dimensional data by least squares to obtain a reference plane.

Moreover, the contamination of the alkaline etching liquid after the roughening treatment was visually observed and evaluated according to the following judgment items. The obtained results are shown in Table 1.
○: Liquid color is gray △: Liquid color is gray to black

Preparation of a thermal negative type lithographic printing plate precursor A thermal negative type image recording layer was formed on the aluminum support obtained by the above procedure by the following procedure to obtain a lithographic printing plate precursor.
<Undercoat layer>
The following undercoat layer coating solution was applied to the aluminum support obtained by the above procedure with a wire bar and dried at 90 ° C. for 30 seconds. The coating amount was 10 mg / m ² .

(Coating solution for undercoat layer)
-Polymer compound A having the following structure (weight average molecular weight: 30,000) 0.05 g
・ Methanol 27g
・ Ion exchange water 3g

(Formation of image recording layer)
The following recording layer coating solution [P-1] was prepared and applied to the above aluminum support using a wire bar. Drying was performed at 115 ° C. for 34 seconds with a hot air dryer to obtain a lithographic printing plate precursor. The coating amount after drying was 1.4 g / m ² .

<Recording layer coating solution [P-1]>
・ Infrared absorber (IR-1) 0.074g
-Polymerization initiator (OS-12) 0.280g
・ Additive (PM-1) 0.151g
・ Polymerizable compound (AM-1) 1.00 g
・ Specific binder polymer (BT-1) 1.00g
・ Ethyl violet (C-1) 0.04g
・ Fluorine-based surfactant 0.015g
(Megafuck F-780-F Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 10.4g
・ Methanol 4.83g
・ 10.4 g of 1-methoxy-2-propanol

  In addition, the polymerization initiator (OS-12) used for the recording layer coating solution refers to those exemplified as the onium salt compound examples represented by the general formula (1). The structures of the infrared absorber (IR-1), additive (PM-1), polymerizable compound (AM-1), binder polymer (BT-1), and ethyl violet (C-1) are shown below. .

(Formation of protective layer)
As described above, the following protective layer coating solution [1] was applied to the surface of the recording layer formed using the recording layer coating solution [P-1] with a wire bar, and 125 ° C. for 75 seconds using a hot air drying apparatus. A protective layer was formed after drying to obtain a lithographic printing plate precursor.
The total coating amount of this protective layer (the coating amount after drying) was 1.6 g / m ² .

<Protective layer coating solution [1]>
・ Synthetic mica (Somasif ME-100, 8% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.) 94 g
Polyvinyl alcohol (CKS-50: saponification degree 99 mol%, polymerization degree 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
58g
・ Daiichi Kogyo Seiyaku Serogen PR 24g
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
-Silica composite organic resin fine particle aqueous dispersion (Optobead 6500M aqueous dispersion) 15g
・ Pure water 1364g

  The lithographic printing plate precursor obtained by the above procedure was exposed, developed and printed by the following procedure to evaluate plate misalignment, stain resistance and printing durability.

Exposure and Development The obtained lithographic printing plate precursor was exposed with a Trendsetter 800II Quantum manufactured by Creo at a resolution of 2400 dpi, an outer drum rotation speed of 200 rpm, and an output of 7 W. The exposure was performed under conditions of 25 ° C. and 50% RH. After the exposure, neither heat treatment nor water washing treatment was performed, and development processing was performed at a conveyance speed (line speed) of 2 m / min and a development temperature of 30 ° C. using an automatic developing machine LP-1310HII manufactured by FUJIFILM Corporation. The developer used was a 1: 4 water diluted solution of DH-N, the developer replenisher was diluted 1: 1.4 water of FCT-421, and the finisher was 1: 1 of GN-2K manufactured by FUJIFILM Corporation. A water dilution was used.

Printing After this plate was mounted on the plate cylinder of the “Color Top 6000” rotary printing machine manufactured by Tokyo Machine Seisakusho, scoring was performed across the plate and the plate cylinder at a printing speed of 100,000 copies / hour. Ten thousand copies were completed. Thereafter, the discrepancies between the ruled lines on the plate and the plate cylinder were visually observed as plate misalignments, and evaluated according to the following judgment items.
○: No plate misalignment ○ △: Some plate misalignment △: There is a plate misalignment, but the allowable level (lower limit)
×: There is a misregistration, not possible.
The obtained results are shown in Table 1.
At the same time, the degree of smearing on the non-image area of the printed matter (the degree of ink adhesion) was visually evaluated as antifouling performance. Judgment items are as follows.
○: Almost not dirty Δ: Slightly dirty but acceptable range Table 1 shows the results obtained.
At the same time, the (image adhesion degree) of the printed image portion was visually evaluated as printing durability.
○: Printed well Δ: Slightly faint but acceptable range Table 1 shows the results obtained.

Further, scratch resistance was evaluated by the following procedure for the obtained lithographic printing plate precursor.
The obtained lithographic printing plate precursor was laminated without sandwiching a slip sheet to form a laminate. Laminate this laminated body on the planographic printing plate precursor already set in the cassette by shifting it by 5 cm from the edge (with 20 stacked plates protruding 5 cm outward from the edge of the plate in the cassette). After that, the edges of the 20 protruding plate materials are pushed in the horizontal direction, and the back aluminum support of the stacked 20 bottom plates is applied to the protective layer surface of the top planographic printing plate precursor in the cassette. While rubbing, it was installed in the cassette. A plate material obtained by rubbing the surface of the protective layer on the back surface of the aluminum support was used as a plate material for evaluation of scratch resistance. The plate material was conveyed from the setting part to a Trend setter 3244 manufactured by Creo Corporation using a loader, and a 50% flat screen image was exposed at a resolution of 2400 dpi at an output of 7 W, an outer drum rotation speed of 150 rpm, and a plate surface energy of 110 mJ / cm ² . After the exposure, development processing was performed in the same manner as the evaluation of plate displacement. The presence or absence of scratches generated in the flat screen image of the obtained lithographic printing plate was visually evaluated. Evaluation was performed by sensory evaluation of 1 point (bad) to 5 points (excellent), and 3 points was set as a practical lower limit level.

The lithographic printing plate precursor thus obtained was evaluated for the ease of bending of the plate by the following procedure.
When a metal plate such as an aluminum alloy plate is bent, the bending deformation of the plate is somewhat restored by elasticity after the processing. This phenomenon is called springback. Usually, a lithographic printing plate precursor is used by bending both ends and fixing the bent portion to a drum called a plate cylinder of an offset printing machine, but the angle of the bent portion remaining on the plate is sufficient with respect to the bent angle. Otherwise, it will be difficult to attach to the plate cylinder. Therefore, generally, after bending at a predetermined angle A, the angle B of the bent portion remaining on the plate is measured, and the difference between A and B is evaluated as the springback amount.
In this example, the lithographic printing plate precursor was wound around a jig having an angle of 135 degrees (angle A) and a curvature radius of 1 mm at the tip and bent. Thereafter, the application of force was stopped, and the bending angle B remaining on the planographic printing plate precursor was measured. When the difference between A and B is 15 degrees or less, it is evaluated as ◯, when it exceeds 15 degrees and 20 degrees or less, it is evaluated as △, and when it exceeds 20 degrees, it is evaluated as △.

Preparation of a thermal positive type lithographic printing plate precursor A thermal positive type image recording layer was formed on the aluminum support obtained by the above procedure by the following procedure to obtain a lithographic printing plate precursor.
The aluminum support obtained in the above procedure, sodium silicate No. 3 aqueous solution _{35 ℃ (Na 2 O: SiO} 2 = 1: 3, SiO 2 content of 30 wt%, Nippon Chemical Industrial Co., concentration 1 mass %) For 10 seconds. Then, the water washing by the spray using well water was performed. Thereafter, a thermal positive type image recording layer shown below was formed on an aluminum support which had been washed and dried.

(Formation of undercoat layer)
Undercoat liquid I having the following composition was applied to an aluminum support and dried at 80 ° C. for 30 seconds to form an undercoat layer. The coating amount after drying was 30 mg / m ² .

<Undercoat liquid I composition>
-Polymer compound represented by the following formula 0.3 g
・ Methanol 100g
・ Water 1g

The image recording layer coating solution A having the following composition is applied onto the undercoat layer, and the Wind Control is set to 7 using the TARFAI PERFECT OVEN PH200 and dried at 140 ° C. for 50 seconds to form the A layer. I let you. The coating amount after drying was 0.85 g / m ² .

<Image recording layer coating solution A composition>
N- (4-aminosulfonylphenyl) methacrylamide / acrylonitrile / methyl methacrylate copolymer (molar ratio 36/34/30, weight average molecular weight 50,000) 1.896 g
-Cresol-novolak resin (m / p = 6/4, weight average molecular weight 4,500, residual monomer 0.8 mass%) 0.237 g
-Cyanine dye A represented by the following formula: 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.063g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ The ethyl violet counter ion is changed to 6-hydroxynaphthalene sulfone 0.05 g
・ Fluorosurfactant (Megafac F-176, manufactured by Dainippon Ink & Chemicals, Inc.) 0.035g
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

A coating liquid B for image recording layer having the following composition is applied on layer A, dried at 120 ° C. for 1 minute to form layer B, and a thermal positive type image recording layer having a two-layer structure is formed. A printing plate master was obtained. The coating amount after drying was 0.15 g / m ^2.

<Image recording layer coating liquid B composition>
-M, p-cresol novolak resin (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol) 0.237 g
-Cyanine dye A represented by the above formula 0.047 g
・ Dodecyl stearate 0.060g
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ Fluorine-based surfactant (Megafac F-176, manufactured by Dainippon Ink & Chemicals, Inc.) 0.110 g
Fluorosurfactant (Megafac MCF-312 (30% by mass), manufactured by Dainippon Ink & Chemicals, Inc.) 0.120 g
・ Methyl ethyl ketone 15.1g
・ 1-methoxy-2-propanol 7.7 g

The lithographic printing plate precursor obtained above was exposed and developed by the following method.
Each lithographic printing plate precursor thus obtained was subjected to a main scanning speed of 5 m / sec and a plate surface energy amount of 140 mJ / cm ² using a TrendSetter 3244 manufactured by CREO equipped with a semiconductor laser having an output of 500 mW and a wavelength of 830 nm and a beam diameter of 17 μm (1 / e ² ). And imagewise exposure. Thereafter, 5.0% by mass of a potassium salt composed of D-sorbite / potassium oxide (K ₂ O) in combination of a non-reducing sugar and a base and an antifoaming agent (Olfin AK-02, manufactured by Nisshin Chemical Co., Ltd.) 0.015 Development processing was performed using an alkaline developer in which 1.0 g of C ₁₂ H ₂₅ N (CH ₂ CH ₂ COONa) ₂ was added to 1 L of an aqueous solution containing mass%. The development processing was performed using an automatic processor PS900NP (Fuji Photo Film Co., Ltd.) filled with a developer at a development temperature of 25 ° C. for 12 seconds. After completion of the development treatment, a lithographic printing plate in which plate making was completed was obtained through a water washing step and treatment with a gum (GU-7 (1: 1)).
Using this plate, plate misalignment evaluation was performed in the same manner as a thermal negative type lithographic printing plate. As a result, no plate misalignment occurred in Examples 1-1 to 1-18, but generation of plate misalignment was observed in Comparative Example 1-1.

Claims (3)

  An aluminum support for a lithographic printing plate obtained by roughening the surface of an aluminum alloy plate, and a tensile test according to JIS Z2241 of the aluminum support after the roughening treatment (tensile speed: 2 mm / min) An aluminum support for a lithographic printing plate, having a tensile strength of 170 to 225 MPa.   The aluminum support for lithographic printing plates according to claim 1, wherein the arithmetic average surface roughness Ra of the surface of the aluminum support is 0.35 to 0.65 µm.   A photosensitive lithographic printing plate precursor comprising an image recording layer provided on the aluminum support according to claim 1.