JP2007185779A - Lithographic printing material and lithographic printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing material which has excellent print-out properties during printing, resistance to foreign matter and resistance to plate wear, and can be developed aboard a printing machine. <P>SOLUTION: This lithographic printing material has a heat-sensitive imaging layer which can be developed aboard the printing machine, formed on a support having a hydrophilic surface. In addition, the heat-sensitive imaging layer contains a polyvinylpyrrolidone, and the former or an adjacent layer thereto contains a photothermal conversion agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate material, and more particularly to a lithographic printing plate material having a thermal image forming layer and used in a computer-to-plate (CTP) system.

  With the digitization of print data, there is a need for CTPs that are inexpensive, easy to handle, and have the same printability as PS plates. In particular, in recent years, a general-purpose thermal processless printing plate that can be applied to a printing press that has a direct imaging (DI) function and that does not require a special chemical development process, and has the same usability as a PS plate. Expectations are growing.

  In recent years, so-called processless printing plates that do not require development processing have been put into practical use as printing plate materials. For example, JP-A-7-1849, JP-A-7-164773, JP-A-9-123387, and JP-A-10-193823 disclose processless printing plates.

  These processless printing plates do not require an automatic development processor, and can be directly printed on a printing machine after being exposed by a plate setter. However, it is difficult for such a printing plate material to give sufficient energy to cure the image forming layer, so that the hardness of the image forming layer becomes weak, and PS plates and thermal plates that have been conventionally used It has been pointed out that the printing durability is reduced compared to the above, and the printing plate surface is easily damaged by impact and foreign matter, and is weak against scratches during handling.

In order to improve this point, a photothermal conversion layer containing a compound that converts laser light into heat and a hydrophilic layer containing a hydrophilic polymer cross-linked with a metal chelate compound are sequentially laminated on a support. Technology (see Patent Document 1), technology having an overcoat layer containing water-soluble celluloses on a hydrophilic image forming layer (see Patent Document 2), hydrophilic thermosensitive layer containing a hydrophobized precursor And a technique having a hydrophobic overcoat layer (see Patent Document 3) is disclosed, but these scratch-improving methods are still not sufficient and do not reach workability and printing durability equivalent to those of conventional printing plates. There was a problem.
JP 2001-92115 A JP 2002-19318 A JP 2004-237605 A

  An object of the present invention is to provide an on-press developable lithographic printing plate material that is excellent in printing performance at the time of printing, excellent in foreign matter resistance, and excellent in printing durability.

The above object of the present invention has been achieved by the following constitution.
1. In a printing plate material having a heat-sensitive image forming layer developable on a printing machine on a support having a hydrophilic surface, the heat-sensitive image forming layer contains polyvinylpyrrolidone, and the heat-sensitive image forming layer or the heat-sensitive image forming layer A lithographic printing plate material comprising a photothermal conversion agent in a layer adjacent to.
2. 2. The lithographic printing plate material according to 1, wherein the photothermal conversion agent is a black pigment.
3. 2. The lithographic printing plate material according to 2, wherein the main component of the black pigment is a metal oxide.
4). The lithographic printing plate material according to any one of 1 to 3, wherein the heat-sensitive image forming layer contains a water-soluble polymerizable compound.
5. A lithographic printing method comprising printing the lithographic printing plate material according to any one of 5.1 to 4 by image exposure, on-press development, and printing.

  With the above configuration of the present invention, there is little loss of paper at the time of printing, excellent printing performance, printing resistance such as development failure and white spots is less likely to occur due to impacts from foreign objects, scratches caused by handling, and scratches. An excellent lithographic printing plate material having excellent printing durability can be provided.

  Hereinafter, embodiments of the present invention will be described.

  The present invention relates to a printing plate material having a heat-sensitive image forming layer developable on a printing machine on a support having a hydrophilic surface, the heat-sensitive image forming layer containing polyvinylpyrrolidone, and the heat-sensitive image forming layer or A layer adjacent to the heat-sensitive image forming layer contains a photothermal conversion agent.

  In particular, the present invention includes polyvinyl pyrrolidone in the heat-sensitive image-forming layer, so that there is little loss of paper at the time of printing at the time of printing, and the printing performance is excellent. It is possible to provide a lithographic printing plate material that is less prone to printing failures such as white spots and white spots, has excellent resistance to foreign matters, and has excellent printing durability.

(Support)
The support having a hydrophilic surface according to the present invention is a support having a surface from which the heat-sensitive image forming layer is removed at the time of printing and having a surface that can become a non-image part, and the support surface is hydrophilized. A support having a hydrophilic surface layer treated and a support provided with a hydrophilic layer containing a hydrophilic substance can be used.

  As the support according to the present invention, as long as the surface shape is within the range specified in the present invention, a known material used as a substrate of a printing plate can be used, for example, a metal plate, a plastic film, a polyolefin, etc. And a composite support obtained by appropriately laminating the above materials.

  The thickness of the support is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate include iron, stainless steel, and aluminum. In the present invention, aluminum or an aluminum alloy (hereinafter referred to as an aluminum plate) is particularly preferable because of the relationship between specific gravity and rigidity. Those subjected to any of the known roughening treatment, anodic oxidation treatment, and surface hydrophilization treatment (so-called aluminum grained plate) are more preferred.

  Various aluminum alloys can be used as the support according to the present invention, for example, metals such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, and aluminum. These alloys are used.

  The aluminum plate used as the support according to the present invention is preferably subjected to a degreasing treatment in order to remove the rolling oil on the surface prior to roughening (graining treatment). As the degreasing treatment, a degreasing treatment using a solvent such as trichlene or thinner, an emulsion degreasing treatment using an emulsion such as kesilon or triethanol, or the like is used. In addition, an alkaline aqueous solution such as caustic soda can be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed only by the degreasing treatment can be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is generated on the surface of the support. In this case, the substrate is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof and desmutted. It is preferable to perform the treatment. Examples of the roughening method include a mechanical method and a method of etching by electrolysis.

The mechanical roughening method used is not particularly limited, but a brush polishing method and a honing polishing method are preferable. The roughening by the brush polishing method is, for example, by rotating a rotating brush using a bristle having a diameter of 0.2 to 0.8 mm, and for example, volcanic ash particles having a particle size of 10 to 100 μm on water. While supplying the uniformly dispersed slurry, the brush can be pressed. The roughening by honing polishing is performed by, for example, uniformly dispersing volcanic ash particles having a particle size of 10 to 100 μm in water, injecting pressure from a nozzle, and causing the surface to collide obliquely with the support surface. Can do. Further, for example, abrasive particles having a particle size of 10 to 100 μm are applied to the support surface so as to be present at a density of 2.5 × 10 ³ to 10 × 10 ³ particles / cm ² at intervals of 100 to 200 μm. Roughening can also be performed by laminating the sheets and applying a pressure to transfer the rough surface pattern of the sheet.

After the surface is roughened by the mechanical surface roughening method, it is preferable to immerse in an aqueous solution of acid or alkali in order to remove the abrasive that has digged into the surface of the support, formed aluminum scraps, and the like. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an aqueous alkali solution such as sodium hydroxide. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. After the immersion treatment with an alkaline aqueous solution, it is preferable to carry out a neutralization treatment by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

The electrochemical surface roughening method is not particularly limited, but a method of electrochemical surface roughening in an acidic electrolyte is preferable. As the acidic electrolytic solution, an acidic electrolytic solution usually used in an electrochemical surface roughening method can be used, but a hydrochloric acid-based or nitric acid-based electrolytic solution is preferably used. As the electrochemical surface roughening method, for example, methods described in Japanese Patent Publication No. 48-28123, British Patent No. 896,563 and Japanese Patent Laid-Open No. 53-67507 can be used. This roughening method can be generally performed by applying a voltage in the range of 1 to 50 volts, but is preferably selected from the range of 10 to 30 volts. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 50 to 150 A / dm ^2. The quantity of electricity, may be in the range of 5000 C / dm ^2, preferably selected from the range of 100~2000C / dm ^2. The temperature at which the roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C.

When electrochemical surface roughening is performed using a nitric acid-based electrolyte as the electrolyte, it can be generally performed by applying a voltage in the range of 1 to 50 volts, but is selected from the range of 10 to 30 volts. Is preferred. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 20 to 100 A / dm ^2. The quantity of electricity, may be in the range of 5000 C / dm ^2, preferably selected from the range of 100~2000C / dm ^2. The temperature at which the electrochemical roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C. The concentration of nitric acid in the electrolytic solution is preferably 0.1 to 5% by mass. If necessary, nitrates, chlorides, amines, aldehydes, phosphoric acid, chromic acid, boric acid, acetic acid, oxalic acid, and the like can be added to the electrolytic solution.

When a hydrochloric acid-based electrolyte is used as the electrolyte, it can be generally applied by applying a voltage in the range of 1 to 50 volts, but is preferably selected from the range of 2 to 30 volts. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 50 to 150 A / dm ^2. The quantity of electricity, may be in the range of ^{100~5000C / dm 2, 100~2000C / dm} 2, and more preferably selected from the range of 200~1000C / dm ^2. The temperature at which the electrochemical roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C. The concentration of hydrochloric acid in the electrolytic solution is preferably 0.1 to 5% by mass.

  After the surface is roughened by the electrochemical surface roughening method, it is preferably immersed in an acid or alkali aqueous solution in order to remove aluminum scraps on the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide.

Among these, it is preferable to use an alkaline aqueous solution. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. In addition, it is preferable that after the immersion treatment with an alkaline aqueous solution, neutralization treatment is performed by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

  The mechanical surface roughening method and the electrochemical surface roughening method may each be used alone for roughing, or the mechanical surface roughening method followed by the electrochemical surface roughening method. You may roughen.

Following the roughening treatment, anodizing treatment is preferably performed. There is no restriction | limiting in particular in the method of the anodizing process which can be used in this invention, A well-known method can be used. By performing the anodizing treatment, an oxide film is formed on the support. For the anodizing treatment, a method of electrolyzing an aqueous solution containing sulfuric acid and / or phosphoric acid at a concentration of 10 to 50% as an electrolytic solution at a current density of 1 to 10 A / dm ² is preferably used. A method of electrolysis at a high current density in sulfuric acid described in Japanese Patent No. 1,412,768, a method of electrolysis using phosphoric acid described in US Pat. No. 3,511,661, chromium Examples thereof include a method using a solution containing one or more acids, oxalic acid, malonic acid and the like. The formed anodic oxidation coating amount is suitably 1 to 50 mg / dm ² , preferably 10 to 40 mg / dm ² . The anodized coating amount is obtained by, for example, immersing an aluminum plate in a chromic phosphate solution (85% phosphoric acid solution: 35 ml, prepared by dissolving 20 g of chromium (IV) oxide in 1 L of water) to dissolve the oxide film, It is obtained from mass change measurement before and after dissolution of the coating on the plate.

  The anodized support may be sealed as necessary. These sealing treatments can be performed using known methods such as hot water treatment, boiling water treatment, water vapor treatment, sodium silicate treatment, dichromate aqueous solution treatment, nitrite treatment, and ammonium acetate treatment.

  Further, after these treatments, as a hydrophilization treatment, a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt ( For example, zinc borate) or a primer coated with a yellow dye, an amine salt or the like is also suitable. Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A No. 5-304358 is covalently used.

  Examples of the plastic film used as the support include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

  In the present invention, among these plastic films, polyester films such as polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and polyethylene naphthalate (hereinafter sometimes abbreviated as PEN) are preferably used as the support. The

  Furthermore, it is preferable to use a support obtained by the method described in JP-A No. 10-10676 and having a thermal dimensional change rate of from 0.001% to 0.04% at 120 ° C. for 30 seconds.

  A preferable polyester film is an unstretched polyester film, a uniaxially stretched polyester film, or a biaxially stretched polyester film.

  Of these, a longitudinally stretched polyester film uniaxially stretched in the film extrusion direction (longitudinal direction) is particularly preferred.

(Applying undercoat layer to support)
In the polyester film support, easy adhesion treatment and undercoat layer coating can be performed in order to give various functions.

  Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment.

  As the undercoat layer, a layer containing gelatin or latex is preferably provided on the polyester film support. Among them, the antistatic undercoat layer described in paragraph Nos. 0044 to 0116 of JP-A-7-191433 is preferably used. Further, a conductive layer such as a conductive polymer-containing layer described in paragraph Nos. 0031 to 0073 of JP-A-7-20596 or a metal oxide-containing layer described in paragraph Nos. 0074 to 0081 of JP-A-7-20596 is provided. It is preferable. The conductive layer may be coated on either side as long as it is on the polyester film support, but it is preferably coated on the opposite side of the image forming functional layer with respect to the support. When this conductive layer is provided, the chargeability is improved, the adhesion of dust and the like is reduced, and white spots failure during printing is greatly reduced.

(Hydrophilic layer)
In the present invention, when the plastic film as described above is used as the support, a hydrophilic layer is provided on the support to obtain a support having a hydrophilic surface.

  In this case, the hydrophilic layer preferably has a porous structure.

  In order to form a hydrophilic layer having a porous structure, the following materials for forming a hydrophilic matrix are preferably used.

  As a material for forming the hydrophilic matrix, a metal oxide is preferable.

(Metal oxide)
The metal oxide preferably contains fine metal oxide particles, and examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like or any other form. The average particle diameter is preferably in the range of 3 to 100 nm, and several kinds of metal oxides having different average particle diameters are used. Fine particles can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

(Colloidal silica)
Among these, colloidal silica can be particularly preferably used. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and can provide good strength. The colloidal silica preferably includes necklace-like colloidal silica, which will be described later, and fine particle colloidal silica having an average particle size of 20 nm or less, and the colloidal silica preferably exhibits alkalinity as a colloidal solution.

  Necklace-shaped colloidal silica is a general term for an aqueous dispersion of spherical silica whose primary particle diameter is of the order of nm, and spherical colloidal silica having a primary particle diameter of 10 to 50 nm bonded to a length of 50 to 400 nm. It means colloidal silica in the form of “pearl necklace”.

  The pearl necklace shape (that is, a pearl necklace shape) means that the image of the state in which the silica particles of colloidal silica are connected and linked has a shape like a pearl necklace.

  In the present invention, porous metal oxide particles having a particle size of less than 1 μm can be contained as a porous material having a hydrophilic layer matrix structure.

(Porous metal oxide particles)
As the porous metal oxide particles, the following porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

(Porous silica, porous silica, porous aluminosilicate particles)
The porous silica particles are generally produced by a wet method or a dry method. In the wet method, the gel obtained by neutralizing the aqueous silicate solution can be obtained by drying and pulverizing, or by pulverizing the precipitate deposited by neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in their porosity and particle size by adjusting the production conditions. As the porous silica particles, those obtained from a wet gel are particularly preferable.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, amorphous composite particles synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, those produced as composite particles of three or more components by adding an alkoxide of another metal during production can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 0.5 ml / g or more in terms of pore volume, more preferably 0.8 ml / g or more, and further preferably 1.0 to 2.5 ml / g. preferable. The pore volume is closely related to the water retention of the coating film. The larger the pore volume, the better the water retention, the less likely to get dirty during printing, and the greater the water volume latitude, but more than 2.5 ml / g When it becomes large, the particles themselves become very brittle, so that the durability of the coating film is lowered. Conversely, if the pore volume is less than 0.5 ml / g, the printing performance may be slightly insufficient.

(Measurement method of pore volume)
Here, the pore volume is measured by using Autosorb-1 (manufactured by Cantachrome) and assuming that the voids of the powder are filled with nitrogen by nitrogen adsorption measurement using a constant volume method. Thus, the relative pressure is calculated from the nitrogen adsorption amount at 0.998.

(Zeolite particles)
Zeolite is a crystalline aluminosilicate, and is a porous body having regular three-dimensional network voids having a pore diameter of 0.3 nm to 1 nm.

  Further, the hydrophilic layer matrix structure constituting the hydrophilic layer can contain layered clay mineral particles. Examples of the layered mineral particles include kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicic acid. Examples thereof include salts (kanemite, macatite, ialite, magadiite, kenyaite, etc.). In particular, the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Further, among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As the size of the flat lamellar mineral particles, the average particle diameter (maximum length of the particles) is less than 1 μm in the state of being contained in the layer (including the case where the swelling process and the dispersion peeling process have been performed). The aspect ratio is preferably 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral. When the particle diameter is larger than the above range, the coating film may be non-uniform, and the strength may be locally reduced. On the other hand, when the aspect ratio is not more than the above range, the number of tabular grains with respect to the addition amount is reduced, the viscosity is insufficient, and the effect of suppressing sedimentation of the particulate matter is reduced.

  The content of the layered mineral particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added in powder form to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. It is preferable to prepare the gel swollen in water and add it to the coating solution.

A silicate aqueous solution can also be used as the other additive material in the hydrophilic layer matrix constituting the hydrophilic layer. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer by a so-called sol-gel method using a metal alkoxide can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Agne Jofusha) or is described in this document. Known methods described in the cited documents can be used.

  In the present invention, a water-soluble resin may be contained. Examples of water-soluble resins include polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, and conjugated diene polymer latex of methyl methacrylate-butadiene copolymer. Examples thereof include resins such as acrylic polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone. As the water-soluble resin used in the present invention, it is preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred. This is because an effect of forming the surface shape of the hydrophilic layer in a preferable state can be obtained by including the polysaccharide in the hydrophilic layer.

  The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 20 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention. Such a concavo-convex structure can be formed by containing an appropriate amount of a filler having an appropriate particle size in the hydrophilic layer matrix. However, the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble solution are added to the hydrophilic layer coating solution. It is preferable that a structure having better printability can be obtained by forming a phase separation when the hydrophilic polysaccharide is applied and dried.

  The shape of the concavo-convex structure (pitch, surface roughness, etc.) is determined depending on the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, the solid content concentration of the coating solution, and the wetness. It is possible to appropriately control the film thickness, drying conditions, and the like.

  In the present invention, the water-soluble resin added to the hydrophilic matrix structure part is preferably present in a state where at least a part thereof is water-soluble and can be eluted in water. This is because even if it is a water-soluble material, when it is cross-linked by a cross-linking agent or the like and becomes insoluble in water, its hydrophilicity is lowered and printability may be deteriorated. Further, it may further contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, tertiary amino groups and quaternary ammonium groups. Examples thereof include acrylic resin and diacrylamine. The cationic resin may be added in the form of fine particles, and examples thereof include a cationic microgel described in JP-A-6-161101.

  In addition, the coating liquid used for coating the hydrophilic layer can contain a water-soluble surfactant for the purpose of improving the coatability, and a Si-based or F-based surfactant can be added. Although it can be used, it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass of the entire hydrophilic layer (solid content as the coating solution).

  The hydrophilic layer can contain a phosphate. In the present invention, since the hydrophilic layer coating solution is preferably alkaline, the phosphate is preferably added as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening during printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

(Thermal image forming layer that can be developed on-machine)
The on-press developable heat-sensitive image forming layer according to the present invention refers to a dampening water or printing with a dampening water at the time of being subjected to a printing process without passing through a developing process after image exposure, that is, in a printing preparation stage. A heat-sensitive image forming layer that can form a printable image by removing a portion of the image forming layer that becomes a non-image portion during printing with ink.

  The heat-sensitive image forming layer according to the present invention (hereinafter sometimes simply referred to as an image forming layer) is a layer capable of forming an image by image exposure, and the heat generation of the layer containing a photothermal conversion agent that converts image exposure light into heat. This is a heat-sensitive image forming layer capable of forming an image.

  The layer containing the photothermal conversion agent is a heat-sensitive image forming layer according to the present invention or a layer adjacent to the heat-sensitive image forming layer.

  Examples of the adjacent layer include a hydrophilic layer provided on the support side of the thermal image forming layer or a protective layer provided on the opposite side of the support of the thermal image layer. In the present invention, it is particularly preferable that the adjacent layer is a hydrophilic layer.

  As the heat-sensitive image forming layer, a so-called negative image forming layer in which the image forming layer in the exposed portion is changed in a direction to be fixed on the hydrophilic layer by heat is preferably used.

  The heat-sensitive image forming layer according to the present invention needs to contain polyvinyl pyrrolidone (hereinafter referred to as PVP).

  The present invention is characterized in that PVP is used as an image forming means. At the same time, PVP also plays a role of holding other materials contained in the image forming layer. PVP dissolves easily in cold water and has the property of self-crosslinking when heated to 150 ° C, but this characteristic is capable of on-machine development and is a factor that has good printing durability, printing performance, and scratch resistance. It is guessed.

  That is, in the present invention, an embodiment containing PVP that can be cross-linked by heating in image exposure is preferable, and the lithographic printing plate material described in the above constitutions 1 to 4 of the present invention is image-exposed to self-crosslink PVP. The image forming method is a preferred embodiment.

  As the PVP according to the present invention, the weight average molecular weight (Mw) is preferably from 2,500 to 3,000,000, more preferably from 6,000 to 2,000,000, from the standpoint of printability and printing durability. .

  The content of PVP in the heat-sensitive image forming layer is preferably 30% by mass to 95% by mass, and particularly preferably 50% by mass to 90% by mass.

  The thermal image forming layer may contain the following materials.

  A wax having a softening point of 40 ° C. or higher and 120 ° C. or lower and a melting point of 60 ° C. or higher and 150 ° C. or lower, saccharides that are water-soluble materials, polyacrylic acid, and salts thereof. The wax is preferably dispersible in water, and the average particle size thereof is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm.

  As the saccharide, an oligosaccharide is preferably used from the viewpoint of proper printing.

  The oligosaccharide refers to disaccharide to decasaccharide, and the content of the oligosaccharide in the layer is preferably 1 to 90% by mass, and more preferably 10 to 80% by mass of the entire layer. Polyacrylic acid and its salts also exhibit the same effect, and can maintain good printability of the hydrophilic layer without fear of lowering the hydrophilicity of the hydrophilic layer.

  The heat-sensitive image forming layer of the present invention preferably contains a water-soluble polymerizable compound.

  The polymerizable compound can be polymerized by light or heat generated by image exposure, and is preferably a water-soluble polymerizable monomer from the viewpoint of printing durability.

  Examples of the water-soluble polymerizable monomer (monomer) used in the present invention include, but are not limited to, the following. For example, a carboxyl group-containing monomer, a sulfone group-containing monomer, a phosphoric acid group-containing monomer, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium salt, etc. A monomer capable of introducing a polar group can be preferably used.

  For example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester maleic acid monooctyl ester, styrene sulfonic acid, 2-acrylamidopropyl sulfonic acid, dimethylaminoethyl acrylate, dimethylaminoethyl Examples include methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, and oxyalkylene-modified glycerin acrylates.

(Photothermal conversion agent)
As described above, the photothermal conversion agent according to the present invention is contained in a layer adjacent to a heat-sensitive image forming layer such as a heat-sensitive image forming layer or a hydrophilic layer.

  An infrared absorbing dye or pigment can be used as the photothermal conversion material, but a pigment is preferably used.

  Examples of the pigment include carbon, graphite, metal, metal oxide and the like, and black pigments such as carbon black and black metal oxide are particularly preferable.

  As carbon, furnace black or acetylene black is particularly preferable. The particle size (d50) is preferably 100 nm or less, and more preferably 50 nm or less.

  As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

  As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.

  As the metal oxide, a material that is black in the visible light region or a material that is conductive or that is a semiconductor can be used.

  In the present invention, it is particularly preferable that the black pigment contains a metal oxide as a main component.

Examples of the material exhibiting black color in the visible light region include black iron oxide (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more kinds of metals described above. The metal oxide is a black complex metal oxide composed of two or more kinds of metal oxides. Specifically, it is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. These can be produced by the methods disclosed in JP-A-8-27393, 9-25126, 9-237570, 9-241529, and 10-231441.

  The composite metal oxide that can be used in the present invention is particularly preferably a Cu-Cr-Mn-based or Cu-Fe-Mn-based composite metal oxide. In the case of a Cu—Cr—Mn system, it is preferable to perform the treatment disclosed in JP-A-8-27393 in order to reduce the elution of hexavalent chromium. These composite metal oxides are colored with respect to the amount added, that is, have good photothermal conversion efficiency. These composite metal oxides preferably have an average primary particle size of 1 μm or less, and more preferably have an average primary particle size in the range of 0.01 to 0.5 μm. When the average primary particle diameter is 1 μm or less, the photothermal conversion ability with respect to the addition amount becomes better, and when the average primary particle diameter is within the range of 0.01 to 0.5 μm, the photothermal conversion ability with respect to the addition amount is obtained. Better. However, the photothermal conversion ability with respect to the addition amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, it is preferable to disperse these composite metal oxide particles by a known method separately before adding them to the layer coating solution to prepare a dispersion (paste). An average primary particle size of less than 0.01 is not preferable because dispersion becomes difficult. A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles. Although the kind of dispersing agent is not specifically limited, it is preferable to use Si type surfactant containing Si element.

Examples of materials that have conductivity or are semiconductors include reduced Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , and TiO ₂ . Examples thereof include TiO (titanium oxynitride, generally titanium black). Further, it is also possible to use those obtained by coating the core material _{(BaSO 4, TiO 2, 9Al} 2 O 3 · 2B 2 O, K 2 O · nTiO 2 , etc.) in these metal oxides. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less.

  A particularly preferable embodiment of the photothermal conversion material is that the infrared absorbing dye and the metal oxide are black complex metal oxides composed of two or more metal oxides.

  As addition amount of these photothermal conversion raw materials, it is 0.1-50 mass% with respect to the layer containing this, 1-30 mass% is preferable, and 3-25 mass% is more preferable.

(Infrared absorbing dye)
Examples of infrared absorbing dyes include organic dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, which are general infrared absorbing dyes. Examples thereof include compounds, phthalocyanine-based, naphthalocyanine-based, azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes.

  Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-280750, JP-A-1-293342, JP-A-2-2074, JP-A-3-26593, 3-30991, 3-34891, 3-36093, 3-36094, 3-36095, 3-42281, 3-97589, 3-103476, 7 -43851, 7-102179, JP-A-2001-117201, and the like. These can be used alone or in combination of two or more.

  The hydrophilicity may be composed of a plurality of layers.

  For example, when a hydrophilic layer lower layer (a hydrophilic layer closer to the support) is provided, the same material as the hydrophilic layer can be used as the material used for the hydrophilic layer lower layer.

  However, the lower layer is less advantageous in that it is porous, and the nonporous material improves the coating strength, so the content of the porous material of the hydrophilic matrix is higher than that of the hydrophilic layer. Is preferably less, more preferably not contained.

  When particles having a particle size of 1 μm or more are contained, the amount of particles added is preferably 1 to 50% by mass, and more preferably 5 to 40% by mass of the entire lower layer.

  Similarly to the hydrophilic layer as the entire lower layer, a low content ratio of materials containing carbon such as organic resin and carbon black is preferable for improving hydrophilicity, and the total of these materials is less than 9% by mass. It is preferable that it is less than 5% by mass.

(Image formation)
Image formation of the printing plate material of the present invention can be performed by heat, but it is particularly preferable to perform image formation by exposure with an infrared laser.

  More specifically, exposure relating to the present invention is preferably scanning exposure using a laser that emits light in the infrared and / or near-infrared region, that is, in the wavelength range of 700 to 1500 nm. A gas laser may be used as the laser, but it is particularly preferable to use a semiconductor laser that emits light in the near infrared region.

  As an apparatus suitable for scanning exposure, any apparatus may be used as long as it can form an image on the surface of a printing plate material in accordance with an image signal from a computer using the semiconductor laser.

In general,
(1) A method of exposing the entire surface of the printing plate material by performing two-dimensional scanning using one or a plurality of laser beams on the printing plate material held by the flat plate-like holding mechanism,
(2) The circumferential direction of the cylinder (main scanning direction) using one or a plurality of laser beams from the inside of the cylinder to the printing plate material held along the cylindrical surface inside the fixed cylindrical holding mechanism ), Scanning the entire surface of the printing plate material by moving it in a direction perpendicular to the circumferential direction (sub-scanning direction),
(3) A printing plate material held on the surface of a cylindrical drum that rotates about an axis as a rotator is rotated in the circumferential direction (main scanning direction) by rotating the drum using one or a plurality of laser beams from the outside of the cylinder. ) And moving in the direction perpendicular to the circumferential direction (sub-scanning direction) to expose the entire surface of the printing plate material.
In the present invention, the scanning exposure method (3) is particularly preferable, and the exposure method (3) is used particularly in an apparatus that performs exposure on a printing apparatus.

(On-press development method and printing method)
In the lithographic printing method of the present invention, the lithographic printing plate material image of the present invention is imaged, subjected to on-press development, and printed.

  The exposed portion of the thermal image forming layer according to the present invention becomes a lipophilic image portion, and the unexposed portion is removed to become a hydrophilic non-image portion.

  The unexposed area can be removed by washing with water, but it is preferable to perform so-called on-press development in which the unexposed area is removed using dampening water and / or ink on a printing press.

The removal of the unexposed part of the image forming layer on the printing machine can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. The various sequences can be performed. In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.
(1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several tens of turns, then an ink roller is brought into contact with the plate cylinder to make one to several tens of turns, and then printing is performed. Start.
(2) As a sequence for starting printing, an ink roller is brought into contact with the plate cylinder to make one to several tens of turns, then a watering roller is brought into contact with the plate cylinder to make one to several tens of turns, and then printing is performed. Start.
(3) As a sequence for starting printing, the watering roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder one to several tens of times, and then printing is started.

  As a printing machine used in the lithographic printing method of the present invention, a conventional lithographic printing machine equipped with a dampening water supply device can be used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

<< Preparation of polyester support >>
(Preparation of support 1)
Using terephthalic acid and ethylene glycol, a polyethylene terephthalate having IV (inherent viscosity) = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) was obtained according to a conventional method.

  After pelletizing this, it is dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, rapidly cooled on a cooling drum at 50 ° C., and not yet thick enough to have an average film thickness of 175 μm after heat setting. A stretched film was prepared.

  The stretching temperature was stretched longitudinally by 1.3 times at 102 ° C. in the former stage stretching and 2.6 times at the latter stage stretching at 110 ° C. Next, it was stretched 4.5 times at 120 ° C. with a tenter. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature.

  Then, after slitting the chuck part of the tenter, knurling was performed on both ends, and after cooling to 40 ° C., the film was wound at 47.1 N / m. Thus, a biaxially stretched polyethylene terephthalate film (support 1) having a thickness of 190 μm was obtained.

  The glass transition temperature (Tg) of this biaxially stretched polyethylene terephthalate film was 79 ° C. The obtained polyethylene terephthalate film had a width (film formation width) of 2.5 m.

《Preparation of underdrawn support》
Both surfaces of the support film obtained above are subjected to a corona discharge treatment of 8 W / m ² / min, and then the following undercoat coating solution a is applied on one surface so as to have a wet film thickness of 10 μm. Later, it was dried at 180 ° C. for 4 minutes. Next, the following undercoat coating solution b was applied so as to have a wet film thickness of 11 μm while performing corona discharge treatment (8 W / m ² / min) thereon, and dried at 180 ° C. for 4 minutes (undercoat surface A). ). Further, the following undercoat coating solution c is applied to the opposite surface so as to have a wet film thickness of 8 μm, dried at 180 ° C. for 4 minutes, and then subjected to corona discharge treatment (8 W / m ² / min). Then, the following undercoat coating solution d was applied to a wet film thickness of 5 μm and dried at 180 ° C. for 4 minutes (undercoat surface B).

(Undercoat coating liquid a)
Styrene / glycidyl methacrylate / butyl acrylate = 60/39/1 ternary copolymer latex Solid content 30% by mass Tg = 75 ° C. 21.00 parts by mass Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 ternary Copolymer latex solid content 30% by mass Tg = 75 ° C. 5.60 parts by mass Anionic surfactant S-1 0.6 parts by mass Pure water 73.00 parts by mass (undercoat coating solution b)
Polyvinyl alcohol Solid content 5% by weight Average molecular weight 1700 5.76 parts by weight Water-soluble copolyester / acrylic component = 64/36 acrylic-modified polyester solids 21.7% by weight 3.10 parts by weight Anionic surfactant S-1 0.011 part by weight Matting agent (silica average particle size 0.5 μm) 0.004 part by weight Hardener H-2 0.058 part by weight Pure water 91.06 part by weight (undercoating liquid c)
Tin oxide sol Solid content 8.3% by mass 10.95 parts by mass n-Butyl acrylate / styrene / glycidyl methacrylate = 40/20/40 ternary copolymer latex Solid content 30% by mass 1.51 parts by mass n-Butyl acrylate / T-butyl acrylate, styrene, hydroxymethyl methacrylate = quaternary copolymer latex of 10/35/27/28, solid content 30% by mass
0.38 parts by weight Anionic surfactant S-1 0.05 parts by weight Pure water 87.11 parts by weight (undercoat coating solution d)
Water-soluble copolyester / acrylic component = acrylic modified polyester having 80/20 solid content 17.8% by weight 14.34 parts by weight Anionic surfactant S-1 0.11 parts by weight Matting agent (silica average particle size 0.5 μm ) 0.20 parts by mass pure water 85.35 parts by mass (preparation of the back coating layer)
Colloidal silica: Snowtex-XS (Nissan Chemical Co., Ltd., solid content 20% by mass)
33.60 parts by mass Acrylic emulsion: DK-05 (Gifu Shellac, solid content 48% by mass)
14.00 parts by weight Matting agent (PMMA average particle size 5.5 μm) 0.56 parts by weight Pure water 51.84 parts by weight Solid content concentration 14% by weight
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a back coating layer coating solution.

Application of Back Coating Layer The coating solution for the back coating layer was applied to the undercoated surface B side by applying a corona discharge treatment of 8 W / m ² / min to the undercoated sample using wire bar # 6. Was passed through the drying zone set to 100 ° C. at a conveyance speed of 15 m / min. The amount of the back coating layer was 2.0 g / m ² .

(Preparation of support 2)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm was immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolved amount became 2 g / m ² , and washed with water. Then, it was immersed in 0.1 mass% hydrochloric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water.

Next, this aluminum plate was subjected to an electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was. The distance between the electrode and the sample surface at this time was 10 mm. Perform electrolytic graining treatment is divided into 12 times, and the quantity of electricity used in one treatment (at a positive polarity) as the 40C / dm ^2, treatment quantity of electricity 480C / dm ² in total (at a positive polarity). In addition, a rest period of 5 seconds was provided between each surface roughening treatment.

After electrolytic surface roughening, it is immersed in a 1% by weight sodium hydroxide aqueous solution kept at 50 ° C. and etched so that the amount of dissolution including the smut of the roughened surface becomes 1.2 g / m ^2. Then, it was washed with water, then immersed in a 10% aqueous sulfuric acid solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water.

Next, anodization was performed in a 20% sulfuric acid aqueous solution so that the amount of electricity was 150 C / dm ² under a constant voltage condition of 20 V, followed by washing with water.

  Next, after squeezing the surface water after washing with water, it was immersed in a 1% by mass sodium dihydrogen phosphate aqueous solution maintained at 70 ° C. for 30 seconds, washed with water, and then dried at 80 ° C. for 5 minutes to obtain a support. Obtained. Ra of the support was 460 nm (measured at 40 times using RST Plus manufactured by WYKO).

(Preparation of hydrophilic layer (upper layer) coating solution)
Colloidal silica (alkaline): SNOWTEX-XS (Nissan Chemical Co., Ltd., solid content 20% by mass) 51.94 parts by mass Porous metal oxide: Shilton JC-40 (Mizusawa Chemical Co., Ltd., porous aluminosilicate particles) 2.22 parts by mass Layered clay mineral montmorillonite: mineral colloid MO (manufactured by Souther Clay Products, average particle size 0.1 μm) was vigorously stirred with a homogenizer to form a 5% by mass water-swollen gel 4.44 parts by mass Cu-Fe-Mn-based metal oxide black pigment: TM-3550 black powder (manufactured by Dainichi Seika Kogyo Co., Ltd., particle size of about 0.1 μm) 40% solid content (of which 0.2% by mass) % Dispersion material) Water dispersion
10.00 parts by mass A 4% by mass aqueous solution of sodium carboxymethylcellulose (a reagent manufactured by Kanto Chemical Co., Inc.)
2.80 parts by mass A 10% by mass aqueous solution of trisodium phosphate dodecahydrate (manufactured by Kanto Chemical Co., Inc.)
0.56 parts by mass Pure water 25.04 parts by mass Solid content concentration 20% by mass
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a hydrophilic layer (upper layer) coating solution.

(Preparation of lower hydrophilic layer coating solution)
(A-1)
Colloidal silica (alkaline): Snowtex-S (manufactured by Nissan Chemical Co., Ltd., solid content 30% by mass) 5.2 parts by mass Necklace-shaped colloidal silica (alkaline): Snowtex-PSM (manufactured by Nissan Chemical Co., Ltd., solid content 20) 11.7 parts by mass Colloidal silica (alkaline): MP-4540 (average particle size 0.4 μm, manufactured by Nissan Chemical Co., Ltd., solid content 30% by mass) 4.5 parts by mass Porous metal oxide particles Shilton JC- 20 (manufactured by Mizusawa Chemical Co., Ltd., porous aluminosilicate particles, average particle size 2 μm) 1.2 parts by mass Porous metal oxide particles SILTON AMT08 (manufactured by Mizusawa Chemical Co., Ltd., porous aluminosilicate particles, average particle size 0.6 μm) 3.6 parts by mass Surface-coated silica particles: STM-6500S (manufactured by Nissan Chemical Co., Ltd., average particle size 6.5 μm)
10.00 parts by mass Layered mineral particles Montmorillonite: A mineral colloid MO (manufactured by Southern Clay Products, average particle size of about 0.1 μm) is vigorously stirred with a homogenizer to form a 5% by mass water-swollen gel. Cu-Fe-Mn-based metal oxide black pigment: TM-3550 black powder (manufactured by Dainichi Seika Kogyo Co., Ltd., particle size of about 0.1 μm) solid content of 40% by mass (of which 0.2% by mass is a dispersing agent) 2.7 parts by mass of aqueous dispersion 4% by mass aqueous solution of sodium carboxymethylcellulose (Kanto Chemical Co., Ltd. reagent)
3.0 parts by mass A 10% by mass aqueous solution of trisodium phosphate / 12 water (reagent manufactured by Kanto Chemical Co., Inc.)
0.6 parts by mass Pure water 62.7 parts by mass Solid content concentration 12% by mass
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a lower hydrophilic layer coating solution.

Apply lower layer hydrophilic layer, hydrophilic layer (upper layer) Lower layer hydrophilic layer coating solution using wire bar # 5 on the back surface (undercoating surface A) of the support coated with the back coating layer 15m Was passed through the drying zone set to 100 ° C. at a conveyance speed of 15 m / min. Subsequently, the coating solution for the hydrophilic layer (upper layer) was applied using wire bar # 3, and passed through a drying zone set at 100 ° C. having a length of 30 m at a conveyance speed of 15 m / min. The amount of each of the lower hydrophilic layer and the hydrophilic layer (upper layer) was 3.0 g / m ² and 0.55 g / m ² . The sample after coating was aged at 60 ° C. for 1 day.

(Preparation of image forming layer coating solution)
An image forming layer coating solution having the following composition is applied on the hydrophilic layer (upper layer) prepared above using wire bar # 4, and a drying zone set at 70 ° C. having a length of 30 m is transported at a speed of 15 m. The image forming layer was formed by passing at a rate of / min. The amount of the image forming layer applied was 0.5 g / m ² . The sample after application was aged at 50 ° C. for 24 hours.

(Image forming layer 1)
Polyvinyl alcohol (KL-506 manufactured by Kuraray Co., Ltd., solid content: 15% by mass)
58.7 parts by weight 20% by weight aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji, melting point 97 ° C.)
1.0 part by weight Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by weight 10.0 parts by weight Pure water 30.3 parts by weight Solid content concentration 10% by weight
(Image forming layer 2)
Polyvinyl pyrrolidone (K-30, 30% by mass)
29.3 parts by weight 20% by weight aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji, melting point 97 ° C.)
1.0 part by weight Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by weight 10.0 parts by weight Pure water 59.7 parts by weight Solid content concentration 10% by weight
(Image forming layer 3)
Polyvinyl pyrrolidone (K-30, 30% by mass)
19.3 parts by weight Water-soluble monomer (A-GLY-3E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 3 parts by weight A 20% by weight aqueous solution of disaccharide lorehalose (trade name Treha, melting point 97 ° C., manufactured by Hayashibara Shoji Co., Ltd.)
1.0 part by mass Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by mass 10.0 parts by mass Pure water 66.7 parts by mass Solid content concentration 10% by mass
(Image forming layer 4)
Polyvinyl alcohol (KL-506 manufactured by Kuraray Co., Ltd., solid content: 15% by mass)
55.3 parts by weight 20% by weight aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji, melting point 97 ° C.)
1.0 part by weight Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by weight 10.0 parts by weight Infrared absorbing dye (American Dye Source, ADS830AT) 3% by weight IPA Solution 16.7 parts by mass Pure water 17.0 parts by mass Solid content concentration 10% by mass
(Image forming layer 5)
Polyvinyl pyrrolidone (K-30, 30% by mass)
27.7 parts by mass A 20% by mass aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji Co., Ltd., melting point 97 ° C.)
1.0 part by weight Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by weight 10.0 parts by weight Infrared absorbing dye (American Dye Source, ADS830AT) 3% by weight IPA Solution 16.7 parts by mass Pure water 44.7 parts by mass Solid content concentration 10% by mass
(Image forming layer 6)
Polyvinyl pyrrolidone (K-30, 30% by mass)
17.7 parts by weight Water-soluble monomer (Shin-Nakamura Chemical Co., Ltd., A-GLY-3E) 3 parts by weight 20% by weight aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji Co., Ltd., melting point 97 ° C.)
1.0 part by weight Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by weight 10.0 parts by weight Infrared absorbing dye (American Dye Source, ADS830AT) 3% by weight IPA Solution 16.7 parts by mass Pure water 51.7 parts by mass Solid content 10% by mass
The lithographic printing plate material was cut to a width of 660 mm and wound about 30 m around a paper core having an outer diameter of 76 mm to obtain a rolled lithographic printing plate material.

(Image formation)
The printing plate material was wound around the exposure drum and fixed. For exposure, a laser beam having a wavelength of 830 nm and a spot diameter of about 20 μm is used. The exposure energy is 250 mJ / cm ² , and 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines are formed. did. The exposed image is a halftone dot image of the entire printing plate material.

(Printing method)
Printing was performed under the following conditions. The printing plate material was attached to the plate cylinder as it was after exposure, and printed using the same printing sequence as the PS plate.

Printing machine: DAIYA F-1 manufactured by Mitsubishi Heavy Industries, Ltd.
Printing paper: OK top coat, Kinmari SW
Printing speed: 6,000 sheets / hour Dampening solution: Astro Mark 3 (manufactured by Nikken Chemical Laboratory) 2% by mass
Ink: (TK High Unity Red by Toyo Ink Co.)
(Evaluation method for the number of printed sheets)
The produced printing plate is exposed to a non-image, 50% halftone dot, and solid image every 2 inches by the above-described image forming method. Next, printing is started under the conditions of the printing method described above, and is stopped when 100 sheets are printed. The number of inks that were neatly turned on and off like an image and no ink entanglement was measured and used as an index for evaluating the printing performance. If it is 30 sheets or less, it is practical.

(Evaluation method for foreign material resistance)
The prepared printing plate is exposed to 50% halftone dots on the entire surface of the printing plate by the image forming method described above. Next, printing is started under the conditions of the printing method described above, and is temporarily stopped when about 50 sheets are printed. With the ink on the printing press blanket, paste a fishing line made of nylon (74, 104, 117, 148, 235 μm) of different thicknesses cut to about 5 mm on the blanket as a substitute for dust and foreign matter. . Thereafter, printing is started, printing is stopped as it is, and then the blanket and the printing plate are washed. Then, printing was performed again, the 50th sheet was sampled, the degree of damage to the printed matter was evaluated, and the maximum thickness value that did not cause scratches was used as an index of foreign matter resistance. What is not damaged up to 148 μm is practical.

(Evaluation method for printing durability)
Printing is performed using Kinmari SW as printing paper. The produced printing plate is exposed to a non-image, 50% halftone dot, and solid image every 2 inches by the above-described image forming method. Next, printing was started under the conditions of the above-described printing method, and evaluation was made with 50% halftone dots or where the blurring started in the solid image portion as the end point. The results are shown in Table 1.

  From Table 1, the printing plate material of the present invention is excellent in printing durability, and in the handling of the printing plate before development, printing failure such as defective development and white spots with respect to impact from foreign matter, scratches due to handling, etc. It can be seen that the workability is equivalent to that of the prior art.

Claims (5)

In a printing plate material having a heat-sensitive image forming layer developable on a printing machine on a support having a hydrophilic surface, the heat-sensitive image forming layer contains polyvinylpyrrolidone, and the heat-sensitive image forming layer or the heat-sensitive image forming layer A lithographic printing plate material comprising a photothermal conversion agent in a layer adjacent to. The lithographic printing plate material according to claim 1, wherein the photothermal conversion agent is a black pigment. The lithographic printing plate material according to claim 2, wherein the main component of the black pigment is a metal oxide. The lithographic printing plate material according to claim 1, wherein the heat-sensitive image forming layer contains a water-soluble polymerizable compound. A lithographic printing method comprising: exposing the lithographic printing plate material according to any one of claims 1 to 4 to image exposure, performing on-press development, and printing.