JP4213756B2 - Planographic printing plate precursor and laminate of planographic printing plate precursor - Google Patents

Description

  The present invention relates to a negative lithographic printing plate precursor capable of direct drawing with an infrared laser beam and capable of high-speed plate making, and a laminate obtained by directly laminating the lithographic printing plate precursor without using a slip sheet.

Conventionally, PS plates having a structure in which an oleophilic photosensitive resin layer is provided on a hydrophilic support are widely used as lithographic printing plate precursors. As a plate making method, mask exposure (typically through a lithographic film) After the surface exposure), 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 according to digitized image information and directly produces a printing plate without going through a lithographic film is eagerly desired. Obtaining a lithographic printing plate precursor adapted to this is an important technical issue.

As such a lithographic printing plate precursor capable of scanning exposure, an oleophilic photosensitive resin layer containing a photosensitive compound capable of generating active species such as radicals and Bronsted acids by laser exposure on a hydrophilic support (hereinafter referred to as “lithographic printing plate precursor”) , Also referred to as a recording layer) has been proposed and is already on the market. This lithographic printing plate precursor is laser-scanned based on digital information to generate active species, which causes physical or chemical changes in the recording layer to insolubilize it, followed by development processing, thereby developing a negative lithographic printing plate Can be obtained.
In particular, a photopolymerization type recording layer containing a photopolymerization initiator excellent in photosensitive speed, an addition-polymerizable ethylenically unsaturated compound, and a binder polymer soluble in an alkali developer on a hydrophilic support, and necessary According to the planographic printing plate precursor (for example, see Patent Document 1) provided with an oxygen-blocking protective layer is excellent in productivity, simple development processing, and good resolution and inking properties, It has desirable printing performance.

Further, in order to improve productivity, that is, to improve plate making speed, photopolymerizability comprising a cyanine dye having a specific structure, an iodonium salt and an addition-polymerizable compound having an ethylenically unsaturated double bond. A recording material that uses the composition as a recording layer and does not require heat treatment after imagewise exposure has been proposed (see, for example, Patent Document 2). This recording material is caused by oxygen in the air during the polymerization reaction. There was a problem that the polymerization was inhibited, the sensitivity was lowered, and the strength of the formed image area was insufficient.
To solve this problem, a method of providing a protective layer containing a water-soluble polymer on the recording layer or a method of providing a protective layer containing an inorganic layered compound and a water-soluble polymer (for example, see Patent Document 3) is known. It has been. The presence of these protective layers prevents polymerization inhibition, promotes the curing reaction of the recording layer, and improves the strength of the image area.

On the other hand, shortening the time required for the exposure process is important as the productivity in the plate making operation of a photopolymerization type lithographic printing plate precursor that is easy to develop. In the exposure process, a laminate in which an interleaving paper having an anti-adhesion function between originals and an anti-scratching function caused by rubbing the surface of a relatively soft protective layer with an aluminum support is usually inserted between the originals. Supplied as Therefore, the slip sheet removal time in the exposure process has been a cause of inefficiency. In order to improve the efficiency in this exposure process, it is sufficient to omit the process of removing the slip sheet by using a laminate that does not insert the slip sheet between the master plates. There has been a need for improvements in adhesion and scratches caused by rubbing the protective layer surface with an aluminum support.
For improving the adhesion resistance between lithographic printing plate precursors, the above-described method of providing a protective layer containing an inorganic layered compound and a water-soluble polymer is effective, but the present situation is that higher scratch resistance is required. It is.

From the above, while suppressing the polymerization inhibition of the recording layer effectively, even when using a laminate in which no interleaf is inserted between the original plates, the adhesion resistance between the lithographic printing plate precursors and the protective layer surface is an aluminum support. There has been a demand for a lithographic printing plate precursor capable of improving the productivity in plate making work with improved scratches caused by rubbing.
Japanese Patent Laid-Open No. 10-228109 Japanese Examined Patent Publication No. 7-103171 JP 11-38633 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, an object of the present invention is to provide a lithographic printing plate precursor that can be written by laser exposure and has a protective layer on the recording layer, and that can improve productivity in plate making operations. There is to do.
More specifically, on the recording layer on which writing by laser exposure is possible, the polymerization inhibition of the recording layer is suppressed, the development removability is excellent, and even when a planographic printing plate precursor is laminated, the planographic printing Provided with a protective layer that suppresses adhesion between the protective layer surface of the plate precursor and the support side surface of the adjacent lithographic printing plate precursor, and can improve the scratches generated between the protective layer surface and the back surface of the aluminum support The purpose is to provide a lithographic printing plate precursor.
Further, a further object of the present invention is to improve productivity by making a plate making operation in which adhesion between the adjacent protective layer and the back surface of the support and damage to the protective layer are suppressed even when laminated without interposing paper. Another object of the present invention is to provide a laminate of a planographic printing plate precursor.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the above object can be achieved by adding organic resin fine particles whose surface is coated with silica to the protective layer located in the uppermost layer, The present invention has been completed.

That is, the lithographic printing plate precursor of the present invention has a polymerizable negative recording layer writable by laser exposure on a support, and an organic resin fine particle coated with silica on the uppermost layer and a hydrophilic polymer. It has the protective layer to contain.
Here, the organic resin used as the core of the resin fine particles coated with silica is made of polyacrylic acid resin, polyurethane resin, polystyrene resin, polyester resin, epoxy resin, phenol resin, and melamine resin. It is preferably at least one resin selected from the group.
The protective layer of the present invention may have a single layer structure or may be a protective layer having a multilayer structure, and at least one of the layers constituting the protective layer is a mica compound. It is a preferable aspect to contain.
Moreover, it is preferable that a support body is an aluminum support body and has the backcoat layer which consists of organic resin in the back surface of this support body.
The lithographic printing plate precursor laminate according to claim 7 of the present invention is characterized in that a plurality of the lithographic printing plate precursors of the present invention are laminated in direct contact with each other.

Although the operation of the present invention is not clear, it is estimated as follows.
Usually, a hydrophilic polymer such as polyvinyl alcohol is used for the protective layer of a lithographic printing plate precursor having a polymerizable negative recording layer because it has excellent oxygen barrier properties. When manufacturing such a lithographic printing plate precursor at a factory production scale, a coating liquid in which organic resin fine particles are added and dispersed in a protective layer coating liquid mainly composed of a polyvinyl alcohol aqueous solution for the purpose of imparting matting properties. When the coating solution is stored for a few hours to a day after the preparation until the start of coating, the hydrophobic organic resin fine particles have low compatibility with the polyvinyl alcohol, which is a hydrophilic polymer. When the protective layer is provided on the recording layer using this coating solution, the organic resin fine particles are unevenly distributed so that the resin layer is not present in the protective layer or the resin particle aggregate is present. Problems arise.

In the present invention, when the organic resin fine particles are added to the hydrophilic polymer as the main component for forming the protective layer, the organic resin fine particles coated with a silica component having excellent compatibility with a hydrophilic resin such as polyvinyl alcohol Is added, the dispersion stability of the organic resin particles is improved, and the above-described problems caused by separation of the organic resin fine particles from the coating liquid are improved.
That is, the organic resin fine particles coated with the silica component are excellent in affinity with the hydrophilic polymer as the film forming component, so that uniform dispersion of the resin particles is achieved and adhesion with the hydrophilic polymer at the particle interface. As a result, it was found that the coating property after coating and drying was improved, and organic fine particles were hardly dropped even when contacted with the outside, and stable scratch resistance was obtained.

  Furthermore, since the silica component coated with organic fine particles is excellent in oxygen barrier properties, it does not cause a decrease in oxygen barrier properties due to resin fine particles, which is usually a concern when organic resin fine particles are added as a matting agent. Even when added to an overcoat layer having an oxygen-blocking function on the mold recording layer, good oxygen-blocking properties can be maintained, and pinholes in the form of fine particles (fine images resulting from inhibition of image formation in exposed areas) It is considered that no scratches are observed and that both excellent scratch resistance and oxygen barrier properties can be achieved.

According to the present invention, a writable by Les Za, and a lithographic printing plate precursor having a protective layer, it is possible to provide a lithographic printing plate precursor capable of improving productivity in plate-making operation. More specifically, the polymerizable negative-type recording layer is writable by Les Za, suppressing polymerization inhibition of the recording layer, excellent in development removability, further, in case of stacking the planographic printing plate precursor However, it is possible to suppress adhesion between the protective layer surface of the lithographic printing plate precursor and the support side surface of the adjacent lithographic printing plate precursor, and to protect the scratches generated between the protective layer surface and the back surface of the aluminum support. A lithographic printing plate precursor having a layer can be provided.
In addition, according to the present invention, even when laminated without intervening paper, adhesion between the adjacent protective layer and the back of the support and damage to the protective layer are suppressed. A laminate of a lithographic printing plate precursor can be provided.

Hereinafter, the present invention will be described in detail.
First, the planographic printing plate precursor of the present invention will be described.
<Lithographic printing plate precursor>
The lithographic printing plate precursor of the present invention is a polymerizable negative type containing an infrared absorber, a polymerization initiator, a polymerizable compound, and optionally a binder polymer on a support, preferably an aluminum support exhibiting surface hydrophilicity. A lithographic printing plate precursor in which a recording layer and a protective layer are sequentially laminated, wherein the protective layer contains organic resin fine particles coated with silica and a hydrophilic polymer, and such protection It has a layer as the uppermost layer of the planographic printing plate precursor.
Hereinafter, each of these components constituting the lithographic printing plate precursor according to the invention will be described.

<Protective layer as the top layer>
According to the present invention, the protective layer (hereinafter referred to as a specific protective layer as appropriate) located at the top of the lithographic printing plate precursor is organic resin fine particles whose surface is coated with silica (hereinafter referred to as silica-coated fine particles as appropriate). And a hydrophilic polymer.
Since the recording layer in the lithographic printing plate precursor according to the present invention is a polymerizable negative type recording layer as will be described in detail below, it is usually in the atmosphere that hinders the image forming reaction in order to perform exposure in the air. A protective layer is provided on the recording layer for the purpose of preventing low molecular weight compounds such as oxygen, moisture, and basic substances present in the recording layer from entering the recording layer.

  A protective layer provided for such a purpose, particularly a specific protective layer located at the uppermost part, was surface-coated with a hydrophilic polymer, preferably a hydrophilic polymer mainly composed of polyvinyl alcohol, and silica. By containing the organic resin fine particles, the stability of the organic resin fine particles in the coating liquid is dramatically increased, and the lithographic printing plate precursor produced using this coating liquid always achieves excellent film strength. In addition, the protective layer can be given a matte property. 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. Further, since excellent matting properties are imparted to the protective layer, when the planographic printing plate precursor of the present invention is laminated, adhesion between the protective layer surface of the planographic printing plate precursor and the back side of the support of the adjacent planographic printing plate precursor And it becomes possible to suppress the rubbing crack which arises between a protective layer surface and an aluminum support body back surface.

As described above, the specific protective layer according to the present invention needs to be present as the uppermost layer of the lithographic printing plate precursor because it can impart matting properties.
Further, when the specific protective layer according to the present invention is a single layer, the mica compound is contained in the layer, and when the protective layer has a laminated structure, the mica compound is added to any of the plurality of layers forming the protective layer. It is preferable to contain it from the viewpoint of improving various properties such as oxygen barrier properties, external pressure resistance, and adhesion resistance.
Hereinafter, each component used for the protective layer according to the present invention will be sequentially described.

(Silica-coated organic resin fine particles)
The silica-coated fine particles of the present invention are formed by surface-coating fine particles made of an organic resin with silica. Organic resin fine particles that serve as a core suppress adhesion between the protective layer surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor, and scratches generated between the protective layer surface and the back surface of the aluminum support. It is added for this purpose. 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 uppermost protective layer to impart appropriate irregularities to its surface and reduce the adhesion surface area.

Further, from the viewpoint of suppressing scratching, the mat particles are preferably those that 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 according to the present invention, any resin having physical properties as described above can be used without limitation, for example, polyacrylic acid resin, Examples include polyurethane resins, 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 invention includes such a state that 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 first 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 in the present invention.

  The silica-coated fine particles that can be used in the present invention are also available as commercial products. As specific examples, silica / melamine composite fine particles include 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 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, Daiichi Seika Co., Ltd. Dynamic Examples thereof include beads CN5070D and dampula coat THU.

The shape of the silica-coated fine particles according to the present invention 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 immobilization on the surface of the protective layer is easy, and the holding function is excellent against contact stress from the outside.
The preferable addition amount of the silica-coated fine particles in the specific protective layer according to the present invention is 5 to 1000 mg / m ² , more preferably 10 to 500 mg / m ² , most preferably 20 to 200 mg / m ² . In addition, the preferable addition amount with respect to the entire protective layer is preferably 0.5 to 95% by mass, more preferably 1 to 50% by mass, and most preferably 2% with respect to the total solid content of the protective layer. It is in the range of ˜20% by mass.

(Other organic resin fine particles)
In the specific protective layer according to the present invention, in addition to the silica-coated organic resin fine particles, other organic resin fine particles (without the silica coating layer) can be used in combination as long as the effects of the present invention are not impaired.
Examples of 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, synthetic resin fine particles have advantages such as easy particle size control and easy control of desired surface characteristics by surface modification.

In such a method for producing organic resin fine particles, a relatively hard resin such as PMMA can be formed into fine particles by a crushing method. 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”, edited by Japan Society for Materials Science, published in 1993. Are described in detail.

  Organic resin fine particles that can be used in combination with silica-coated fine particles in the specific 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 made by Kasei Kogyo Kogyo, 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, W 10, 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 specific protective layer according to the present invention is in the range of 0.90 to 1.30, and the average particle diameter is preferably 2.0 to 15 μm, The true specific gravity is in the range of 0.90 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)
Since the lithographic printing original plate of the present invention has a polymerizable negative recording layer, it is preferable to provide a protective layer having excellent oxygen barrier properties.
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 for 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 has excellent adhesion to the recording layer, its surface (outermost surface) has low adhesion to other materials, and is easy in the development process after exposure. Polymers that can be removed easily 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 present invention 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. Therefore, the protective layer according to the present invention preferably contains, for example, polyvinyl alcohol having a saponification degree of 91 mol% or more as a main component, and further uses a mica compound in any one of the protective layers as will be described later. As a result, the oxygen barrier property of the protective 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 in the present invention 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 specific protective layer according to the present invention include KL-118, KM-618, KM-118, SK-5102, MP-102, and R manufactured by Kuraray Co., Ltd. -2105, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenal CKS-50, T-HS-1, T-215, T-350, T-330, T-330H, AF manufactured by Nihon Ventures & Poval Co., Ltd. -17, AT-17 and the like.

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 in the present invention 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. Select.

(Preparation of coating solution for forming specific protective layer)
In the formation of the specific protective layer according to the present invention, the silica-coated fine particles and optionally used organic resin fine particles are supplied in a powder form 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 directly in aqueous solution. 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.

Various additives can be added to the specific protective layer depending on the purpose, in addition to the above-described components, as long as the effects of the present invention are not impaired.
For example, a colorant (water-soluble dye) that is excellent in the transparency of light used for exposing the recording layer (infrared light in the present invention) and can efficiently absorb light having a wavelength that is not related to exposure. It may be added. Thereby, safelight aptitude can be improved, without reducing a sensitivity.

[Layer structure of protective layer]
The protective layer in the lithographic printing plate precursor according to the invention may have a single layer structure or a multilayer 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)
For the protective layer in the lithographic printing plate precursor according to the invention, 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 present invention 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 in the present invention include muscovite, soda mica, phlogopite, biotite, and sericite. As the synthetic mica, non-swelling 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 Swellable mica such as _{/ 5} Li _1/8 (Si ₄ O ₁₀ ) F ₂ . In addition, synthetic smectites are also useful.

In the present invention, among 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 charge, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers 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 layers is Li ⁺ or Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, 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 used in the present invention, it has a plate-like particle shape, and from the viewpoint of adsorption to the organic resin fine particles, the thinner the better, the planar size is the coated surface As long as the smoothness and the transmittance of actinic rays are not impaired, 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 in the present invention is 0.3 to 20 μm, preferably 0.5 to 10 μm, 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 in the present invention is prepared by stirring and mixing a dispersion in which silica-coated fine particles are dispersed and a dispersion in which a mica compound used in combination is dispersed, and the dispersion and a binder component containing polyvinyl alcohol (or And an aqueous solution in which a binder component containing polyvinyl alcohol is dissolved) is coated on the recording layer. It should be noted that the blending order of the silica-coated fine particles, the mica compound and the hydrophilic polymer at the time of preparing 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 the 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 specific polyvinyl alcohol is dissolved). In the case where it does not coexist with silica-coated fine particles in the same layer, this dispersion and a 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 coating the protective layer according to the present invention is not particularly limited, and a method described in US Pat. No. 3,458,311 or JP-A-55-49729 can be applied.

The coating amount of the protective layer according to the present invention, when the protective layer having a single layer structure ^is preferably from ^{0.1g / m 2 ~4.0g / m 2} , 0.3g / m 2 ~3.0g / it is more preferably m ^2. 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 recording layer contains a water-soluble polymer having excellent oxygen barrier properties and a mica compound. It is preferable from the viewpoint of compatibility.

<Recording layer>
The lithographic printing plate precursor according to the invention has a recording layer (photosensitive layer) that is sensitive to laser, that is, writable by laser exposure . The recording layer contains a sensitizing dye, a polymerization initiator, a polymerizable compound, and a binder polymer as essential components, and further contains a colorant and other optional components as necessary. It is.

The polymerizable negative recording layer in the present invention 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 infrared laser irradiation (exposure), and the electrons in the electronically excited state Transfer, energy transfer, heat generation (photothermal conversion function) and the like 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.

In the present invention, the lithographic printing plate precursor according to the above aspect is particularly suitable for plate making directly drawn with an infrared laser beam having a wavelength of 750 to 1400 nm because the recording layer contains an infrared absorber as a sensitizing dye. As compared with the conventional lithographic printing plate precursor, it can exhibit high image forming properties.
Below, each component which comprises the recording layer based on this invention is demonstrated.

(Sensitizing dye)
The recording layer according to the present invention 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 electronically excited state by laser exposure at a wavelength suitable for the sensitizing dye, and electron transfer, energy transfer, and the like related to the electronically excited state act on the polymerization initiator described later, and are high in 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 recording layer in the present invention 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 the sensitizing dye used in the present invention are polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal). ), Cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines (eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin) , Acriflavine), phthalocyanines (eg, phthalocyanine, metal phthalocyanine), porphyrins (eg, tetraphenylporphyrin, central metal-substituted porphyrin), chlorophylls (eg, chlorophyll) Chlorophyllin, central metal-substituted chlorophyll), metal complexes, anthraquinones (for example, anthraquinone), squalium (for example, squalium), and the like, for example, paragraph numbers [0188] to [0188] to [ [0258] can be selected as appropriate and used as a sensitizing dye in the present invention.

Among these, the recording layer in the present invention 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 which is a particularly preferable sensitizing dye used in the present invention, 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 salt 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, cyanine dyes described in JP-A-59-216146, U.S. 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 the formula (I) and (II) in US Patent 4,756,993 can be mentioned.
Other preferable examples of the infrared absorbing dye in the present invention 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 including 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 represent a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the 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 or 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 recording layer coating solution. Hexafluorophosphate ions and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (a) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. Can do.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.
However, those containing no halogen ion as the counter ion are particularly preferred.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 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” (Shobobo), “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 recording layer can be obtained, and a uniform 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 recording layer according to the present invention, 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 present invention has a function of initiating and advancing the curing reaction of a polymerizable compound described later, and is a thermal decomposition type radical generator that decomposes by heat to generate radicals, and excitation of an infrared absorber. Electron transfer type radical generator that accepts electrons and generates radicals, or electron transfer type radical generator that generates electrons by transferring electrons to an excited infrared absorber, and so on to give radicals. Any compound may be used as long as it is generated. 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 present invention, 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 present invention include iodonium salts and diazonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators.
Other onium salts in the present invention include onium salts represented by the following general formulas (II) and (III).

In the 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 ) ⁻ .

  In the present invention, onium salts represented by general formula (II) ([OI-1] to [OI-10]) and onium salts represented by general formula (III) ([ Specific examples of ON-1] to [ON-5] are given below, but are not limited thereto.

  Specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) in the present invention include those described in JP-A No. 2001-133696.

  The polymerization initiator (radical generator) used in the present invention 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 invention is from 0.1 to 50% by mass, preferably from 0.1 to 50% by mass, based on the total solid content constituting the recording layer, from the viewpoint of sensitivity and generation of smudges in the non-image area during printing. It is 5-30 mass%, Most preferably, it is 1-20 mass%.

As a polymerization initiator in this invention, only 1 type may be used and 2 or more types may be used together. 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 recording layer in the invention, 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 present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one, preferably two or more ethylenically unsaturated bonds. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. 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 ··· formula (wherein, ^{R a} and ^{R b} represent H or CH _3.)

  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 lithographic printing plate precursor according to the invention, a specific structure may be selected for the purpose of improving adhesion to a support or a protective layer described later.

Regarding the content of the addition polymerizable compound in the recording layer composition, the solid content in the recording layer composition is considered in terms of sensitivity, occurrence of phase separation, adhesiveness of the recording layer, and precipitation from the developer. The amount is preferably 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 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. Furthermore, in the lithographic printing plate precursor according to the invention, a layer constitution / coating method such as undercoating or overcoating can be carried out.

(Binder polymer)
The binder polymer used in the present invention 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. 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 represents a linking group having a total atom number 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. The “main skeleton of the linking group” in the present invention refers to an atom or an atomic group used only for linking A and the terminal COOH in the general formula (i), and particularly when there are a plurality of linking paths. Refers to an atom or atomic group that constitutes a path with the smallest 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 one or more by any substituent. 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 is 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 preferable, 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 Group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′- Arylureido 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'-a 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 , 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 NHS 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 ), an alkylarylphosphono group (—PO ₃ (a lkyl) (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 conjugated base group, a dialkyl phosphono group _{(-OPO 3 (alkyl) 2)} , diaryl phosphono group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphono group (- _{OPO 3 (alkyl) (aryl)} ), monoalkyl phosphono group _(-OPO 3 H _(alkyl)) and its conjugated base group, monoarylphosphono group _(-OPO 3 H _(aryl)) and its conjugate base group, a cyano group, a nitro group, a dialkyl boryl group (-B _{(alkyl) 2),} Jiariruboriru group (-B ( _RYL) 2), alkyl aryl boryl group (-B (alkyl) (aryl) ), dihydroxy boryl group (-B _{(OH) 2)} and its conjugated base group, an alkyl hydroxy boryl group (-B (alkyl) (OH) ) And conjugated base groups thereof, arylhydroxyboryl groups (-B (aryl) (OH)) and conjugated base groups thereof, aryl groups, alkenyl groups and alkynyl groups.

  In the lithographic printing plate precursor according to the invention, although 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 is , Because it tends to lower the printing durability. 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.

When A in the general formula (i) is NR ³ —, R 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 group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, sec-butyl group, 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 furyl, thienyl, pyrrolyl, pyridyl, and quinolyl groups.
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 present invention 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 present invention 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 recording layer composition and the binder polymer that may be used in combination can be determined as appropriate, but is usually 10 to 90 with respect to the total mass of the nonvolatile components in the recording layer composition. It is mass%, Preferably it is 20-80 mass%, More preferably, it is the range of 30-70 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 a radical, 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, the recording layer according to the present invention may further contain other components suitable for its use and production method. Hereinafter, preferred additives will be exemplified.

-Colorant-
A dye or pigment may be added to the recording layer according to the present invention 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 nonvolatile components in the entire recording layer composition.

-Polymerization inhibitor-
In the recording layer according to the present invention, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the polymerizable compound having an ethylenically unsaturated double bond, that is, the 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 recording layer composition. 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 recording layer composition.

-Other additives-
Furthermore, the recording layer according to the present invention may be added with known additives such as inorganic fillers for improving the physical properties of the cured film, other plasticizers, and oil-sensitizing agents that can improve the ink deposition properties of the recording layer surface. 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 the recording layer according to the present invention, in order to enhance the effect of heating and exposure after development for the purpose of improving the film strength (printing durability) described later, addition of a UV initiator, a thermal crosslinking agent, etc. Can also be done.

[Support]
(Surface treatment of support)
As the support in the present invention, a support subjected to a hydrophilization treatment as described later is used. Examples of such a support include paper, polyester film or aluminum plate. Among them, a surface having good dimensional stability, relatively inexpensive, and excellent hydrophilicity and strength by surface treatment as required. An aluminum plate that can be provided is more preferred. A composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable.

  The aluminum plate as the most preferable support in the present invention is a metal plate mainly composed of dimensionally stable aluminum, and contains pure aluminum plate, aluminum as a main component, and a trace amount of foreign elements. An alloy plate or aluminum (alloy) is selected from a laminated or vapor-deposited plastic film or paper. In the following description, the above-mentioned support made of aluminum or an aluminum alloy is generically used as an aluminum support. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is 10% by mass or less. In the present invention, a pure aluminum plate is suitable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. Thus, the composition of the aluminum plate applied to the present invention is not specified, and a conventionally known publicly available material such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. It can be used as appropriate.

Moreover, the thickness of the aluminum support body used for this invention is about 0.1 mm-about 0.6 mm. This thickness can be changed as appropriate according to the size of the printing press, the size of the printing plate, and the desire of the user.
Such an aluminum support is subjected to a surface treatment described later to be hydrophilized.

(Roughening treatment)
Examples of the roughening treatment method include mechanical roughening, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, the electrochemical surface roughening method in which the surface is electrochemically roughened in hydrochloric acid or nitric acid electrolyte solution, the aluminum surface is scratched with a metal wire, the wire brush grain method, the surface of the aluminum is polished with a polishing ball and an abrasive. A mechanical graining method such as a pole grain method, a brush grain method in which the surface is roughened with a nylon brush and an abrasive, can be used, and the above roughening methods can be used alone or in combination. Among them, a method usefully used for roughening is an electrochemical method in which roughening is chemically performed in hydrochloric acid or nitric acid electrolyte, and a suitable amount of electricity during anode is 50 C / dm ^{2 to} 400 C / dm ² . It is a range. More specifically, in the electrolytic solution containing from 0.1 to 50 percent of hydrochloric acid or nitric, temperature 20 to 80 ° C., for 1 second to 30 minute, alternating at a current density of 100C ^/ dm ² ~400C ^/ dm 2 It is preferable to perform direct current electrolysis.

  The roughened aluminum support may be chemically etched with acid or alkali. Etching agents suitably used are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. Preferred ranges of concentration and temperature are 1 to 50% and 20%, respectively. ~ 100 ° C. Pickling is performed to remove dirt (smut) remaining on the surface after etching. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borohydrofluoric acid and the like are used. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. After the treatment as described above, the method and conditions are not particularly limited as long as the surface roughness Ra of the treated surface is about 0.2 to 0.5 μm.

(Anodizing treatment)
The aluminum support that has been treated as described above to form an oxide layer is then anodized.
In the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or an aqueous solution of boric acid / sodium borate is used as a main component of the electrolytic bath singly or in combination. In this case, the electrolyte solution may of course contain at least components normally contained in at least an Al alloy plate, an electrode, tap water, groundwater, and the like. Further, the second and third components may be added. Here, the second and third components are, for example, metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and ammonium ions. Examples include cations, nitrate ions, carbonate ions, chloride ions, phosphate ions, fluorine ions, sulfite ions, titanate ions, silicate ions, borate ions, and the like, and the concentration is 0 to 10,000 ppm. May be included. There are no particular limitations on the conditions of the anodizing treatment, but the treatment is preferably performed by direct current or alternating current electrolysis at a treatment liquid temperature of 10 to 70 ° C. and a current density of 0.1 to 40 A / m ² at 30 to 500 g / liter. . The thickness of the formed anodic oxide film is in the range of 0.5 to 1.5 μm. Preferably it is the range of 0.5-1.0 micrometer. The support produced by the above treatment is treated so that the pore diameter of the micropores existing in the anodized film is in the range of 5 to 10 nm and the pore density is in the range of 8 × 10 ¹⁵ to 2 × 10 ¹⁶ pieces / m ^2. It is preferred that the conditions are selected.

As the hydrophilization treatment of the support surface, widely known methods can be applied. As a particularly preferable treatment, a hydrophilic treatment with silicate or polyvinylphosphonic acid is performed. A film | membrane is formed by 2-40 mg / m < ² > as Si or P element amount, More preferably, it is 4-30 mg / m < ² >. The coating amount can be measured by fluorescent X-ray analysis.

  The hydrophilization treatment is carried out by applying an anodized film to an aqueous solution containing 1 to 30% by mass, preferably 2 to 15% by mass of alkali metal silicate or polyvinylphosphonic acid, and having a pH of 10 to 13 at 25 ° C. This is carried out by immersing the aluminum support on which is formed, for example, at 15 to 80 ° C. for 0.5 to 120 seconds.

  As the alkali metal silicate used for the hydrophilization treatment, sodium silicate, potassium silicate, lithium silicate, or the like is used. Examples of the hydroxide used for increasing the pH of the aqueous alkali metal silicate solution include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In addition, you may mix | blend alkaline-earth metal salt or Group IVB metal salt with said process liquid. Alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and water-soluble substances such as sulfate, hydrochloride, phosphate, acetate, oxalate, and borate. Salt. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium fluoride titanium, potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, zirconium tetrachloride, etc. Can be mentioned.

  Alkaline earth metal salts or Group IVB metal salts can be used alone or in combination of two or more. A preferable range of these metal salts is 0.01 to 10% by mass, and a more preferable range is 0.05 to 5.0% by mass. Silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. Surface obtained by combining a support with electrolytic grains as disclosed in JP-B-46-27481, JP-A-52-58602, JP-A-52-30503, and the above anodizing treatment and hydrophilization treatment Processing is also useful.

(Backside treatment of support)
The lithographic printing plate precursor according to the invention is preferably modified on the back side of the support for the purpose of further improving scratch resistance. As a method for modifying the back surface of the support, for example, when an aluminum support is used, a method of uniformly forming an anodic oxide film on the entire back surface as in the recording layer side or a back coat layer is formed on the back surface. The method of doing is mentioned. 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 forming 0.6 g / m ² or more of an anodic oxide film uniformly on the entire surface in the same manner as on the recording layer side on the back surface of the aluminum support will be described. The formation of the anodized film is performed by the same means as described in the support surface treatment. 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. a 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.

In the present invention, the 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. The center part of the surface having the oxide film and the end part 5 cm from both ends in the direction (Transverse Direction) passing through the center part and orthogonal to the processing direction (Machine Direction) are both 0.6 g of anodic oxide film amount. / M ² or more.

(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 in the present invention, any composition may be used, and in particular, a metal oxide obtained by hydrolysis and polycondensation of an organometallic compound or an inorganic metal compound described in detail below. A back coat layer comprising a colloidal silica sol or a back coat 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 in the present invention includes 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 an alkali and a polycondensation reaction in water and an organic solvent. A backcoat layer is preferred.
Examples of the organic metal compound or inorganic metal compound used for forming the backcoat layer include metal alkoxide, metal acetylacetonate, metal acetate, metal oxalate, metal nitrate, metal sulfate, metal carbonate, metal oxychloride. , Metal chlorides, and condensates obtained by partial hydrolysis of these to form oligomers.
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). As specific examples, 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. _{Moreover, CH 3 Si (OCH 3)} 3, C 2 H 5 Si (OCH 3) 3, CH 3 Si (OC 2 H 5) 3, mono-substituted silicon, such as _{C 2 H 5 Si (OC 2} H 5) 3 Alkoxides are also used.

These organometallic compounds or inorganic metal compounds can be used alone or in combination of two or more. Among these organic metal 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 preferred. Specific examples of such a silane coupling agent include 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 silane coupling agent substituted with the fluorine-substituted alkyl group is included in the organic fluorine compound in the present invention. 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. The solvent is not particularly limited 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. ² is more preferable.

(2-2. Backcoat layer made of organic resin film)
Another preferred example of the back coat layer in the present invention includes a back coat layer comprising an organic resin film formed on the back surface of the support.
Examples of a preferable resin that can form the backcoat layer in this embodiment include thermosetting resins such as urea resin, epoxy resin, phenol resin, melamine resin, and diallyl phthalate resin. Among these, a phenol resin is preferable from the viewpoint that the physical strength of the formed layer is high, and more specifically, for example, a phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m− / p. Preferred are novolak resins and pyrogallol acetone resins such as mixed cresol formaldehyde resins, 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 (weight 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 in the present invention for the purpose of improving the coating surface properties and controlling the surface properties. As the surfactant used here, 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 non-ionic surfactants such as fatty acid esters of polyoxy compounds, polyalkynelene oxide condensation type, polyethyleneimine condensation type, fluorine-based surfactants, etc. A fluorochemical surfactant is preferred.
The addition amount of the surfactant is appropriately selected depending on the purpose, but can be generally 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 fluorochemical surfactant will be described in detail.
Fluorosurfactants that can be used particularly favorably 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 represent 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 in the structure, an ether group, an ester group, an amide 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 and the 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 that about 0.5 to 10% by mass of such a fluorosurfactant is contained 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 means for applying the backcoat layer coating solution to the support surface include a bar coater, a roll coater, a gravure coater, a known coater, such as a curtain coater, an extruder, and a slide hopper. Non-contact quantitative coaters such as curtain coaters, extruders, slide hoppers, etc. are particularly preferred from the viewpoint of not scratching the surface.

The thickness of the back coat layer of the present invention 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. Preferably there is. In 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 according to the invention is provided with a recording layer and a protective layer in this order on a support, and further, if necessary, an undercoat layer. 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 them on a support.

When the recording layer is applied, the recording layer components are dissolved in various organic solvents to form a recording layer coating solution, which is applied onto the 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 concentration of the solid content in the recording layer coating solution is suitably 2 to 50% by mass.

The coating amount of the recording layer mainly affects the sensitivity of the recording layer, the developability, the strength and printing durability of the exposed film, 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. As the planographic 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 according to the invention may be provided with an intermediate layer (undercoat layer) for the purpose of improving the adhesion and soiling between the recording layer and the 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, the plate making method of the planographic printing plate of the present invention will be described.
The plate making method of the lithographic printing plate of the present invention comprises the step of setting a laminate comprising a plurality of the above-described lithographic printing plate precursors of the present invention in direct contact with the protective layer and the back surface of the aluminum support in a plate setter. Then, 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 is substantially subjected to a heating speed of 1.25 m / min without any heat treatment. Development processing is performed.
Even if the lithographic printing plate precursor of the present invention described above is laminated without interposing the interleaf, the adhesion between the lithographic printing plate precursors and the generation of scratches on the protective layer are suppressed. It can be applied to such a plate making method.
According to the plate-making method of the lithographic printing plate of the present invention, since the laminated body obtained by laminating the lithographic 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. To do.

  Needless to say, this plate making method is also suitable for plate making of the above-described lithographic printing plate precursor according to the present invention, but contains at least an infrared absorber, a polymerization initiator, and a polymerizable compound, and is 750 nm to 1400 nm. The present invention can be suitably applied to any lithographic printing plate precursor provided with a polymerizable negative type recording layer whose solubility in an alkaline developer is reduced by exposure at a wavelength of. Specifically, it may be a recording layer containing each component of “infrared absorber, polymerization initiator, and polymerizable compound” explained in the column of each component constituting the recording layer of the lithographic printing plate precursor according to the invention. What is necessary is just to include a well-known thing as a binder polymer, and does not need to contain it.

  The recording layer to which the lithographic printing plate making method of the present invention is applied has a development rate of 80 nm / sec or more in an unexposed portion with respect to an alkaline developer having a pH of 10 to 13.5, and exposure of the alkaline developer. It is preferable that the penetration rate in the part has a physical property of 50 nF / sec or less. The method for measuring the developing speed of the unexposed portion of the recording layer and the penetration speed of the alkaline developer into the recording layer after curing is the method described in Japanese Patent Application No. 2004-248535 filed earlier by the present applicant. Can be used. Control of the development speed of the unexposed portion of the recording layer and the penetration speed of the alkaline developer into the recording layer after curing can be performed by a conventional method, but as a typical method, a method using the specific binder polymer In addition, the addition of a hydrophilic compound is useful for improving the developing speed of the unexposed area, and the means for adding a hydrophobic compound is useful for suppressing the penetration of the developer into the exposed area.

〔exposure〕
The light source used in the exposure process in the present invention, as long as it is capable of exposing a wave length corresponding to the sensitizing dyes used may be any, but is mentioned as an infrared laser is preferred. Especially, in this invention, it is preferable to image-expose with the solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 750 nm-1400 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used 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, the recording layer does not sufficiently cure. If the exposure energy is too high, the recording layer may be laser ablated and the image may be damaged.

  In the exposure processing in the present invention, exposure can be performed by overlapping light beams of 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 scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.

  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. Further, by performing neither heat treatment nor water washing treatment, stable high-speed processing is possible in development processing.

〔developing〕
In the development processing in the present invention, the non-image portion of the 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 needs to be 1.25 m / min or more. Preferably, it 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 the 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 in the present invention 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. preferable. Among these, the aromatic anionic surfactant used in the present invention 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, and specifically, a single bond, a methylene group or an ethylene group is preferable, and a single bond is particularly preferable.
(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 recording layer components are lowered, and when the content is 10% by mass or more, the printing durability of the printing plate is reduced. .

In addition to the aromatic anionic surfactant, other surfactants may be used in combination with the developer according to the present invention. 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)
The developer according to the present invention preferably contains a chelating agent for a divalent metal, for example, for the purpose of suppressing 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 (polymetalin). 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 2-phosphonobutane tricarboxylic acid-1,2,4, potassium salt thereof, sodium salt thereof; 2-phosphonobutanone tricarboxylic acid-2, in addition to aminopolycarboxylic acids such as potassium salt, sodium salt thereof, etc. 3,4, its potassium salt, its sodium salt; 1-phosphonoethanetricarboxylic acid-1,2,2, its potassium salt, its sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, its potassium salt, Examples thereof include organic phosphonic acids such as aminotri (methylenephosphonic acid), potassium salt, sodium salt, etc. Among them, ethylenediaminetetraacetic acid, potassium salt, sodium salt, amine salt; ethylenediamine; Tetra (methylenephosphonic acid), its ammonium salt, its potash Salt; hexamethylenediamine 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 according to the present invention 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 alkaline agent used in the developer according to the present invention include tribasic sodium phosphate, potassium, ammonium, sodium borate, potassium, ammonium, sodium hydroxide, potassium, ammonium, and lithium. Inorganic alkaline agents such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine And organic alkali agents such as diisotopanolamine, 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 used in the present invention is composed of silicon oxide SiO ₂ which is a silicate component as a hydrophilizing component of a support and alkali oxide M ₂ O as an alkali component (M represents an alkali metal or ammonium group). By adjusting the mixing ratio and concentration, it can be easily adjusted to the optimum range. The mixing ratio (SiO ₂ / M ₂ O molar ratio) of silicon oxide SiO ₂ and alkali oxide M ₂ O is the amount of unstained dirt caused by excessive dissolution (etching) of the anodized film of the support. From the viewpoint of suppressing the generation of insoluble gas due to complex formation between dissolved aluminum and silicate, the range is preferably 0.75 to 4.0, more preferably 0.75 to 3.5. Used in.

In addition, the alkali silicate concentration in the developer includes the effect of inhibiting dissolution (etching) of the anodic oxide film on the support, the developability, the effect of inhibiting precipitation and crystal formation, and the gelation during neutralization during waste From the viewpoint of the prevention effect and the like, the SiO ₂ amount 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 addition to the above components, the following components can be used in combination in the developer used in the present invention, if necessary. 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 used in the present invention 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.

    Further, 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 preferred development replenisher of the present invention contains an oxycarboxylic acid chelating agent having an ability to form a water-soluble chelate compound with aluminum ions, an alkali metal hydroxide, and a surfactant, and contains a silicate. A developing replenisher characterized by being an aqueous solution having a pH of 11 to 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, 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 of the present invention, for the purpose of improving the image strength and printing durability, the image after development can be subjected to whole surface post-heating or whole surface 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 strengthening action cannot be obtained, and if it is too high, problems such as deterioration of the 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.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited thereto.
(Preparation of aqueous dispersion of silica-coated fine particles)
(1) Preparation of Optobead 6500M Water Dispersion In 74 g of pure water, 3.0 g of nonionic surfactant (Emulex 710, manufactured by Nippon Emulsifier Co., Ltd.) and carboxymethylcellulose (No. 1) were added for the purpose of improving dispersion stability. Dissolve 3.0 g of Ito Kogyo Seiyaku Co., Ltd. Cellogen PR). To this aqueous solution was added 20.0 g of silica composite cross-linked melamine resin fine particles (manufactured by Nissan Chemical Industries, Ltd., Opt Bead 6500M), and dispersed with an ace homogenizer manufactured by Nippon Seiki Seisakusho Co., Ltd. at 10,000 rpm for 15 minutes. A bead 6500M aqueous dispersion was obtained.

(2) Preparation of Art Pearl J-7P Water Dispersion Silica composite crosslinked acrylic resin fine particles (Art Pearl J-7P manufactured by Negami Kogyo Co., Ltd.) instead of Opto beads 6500M of the above-mentioned Opto beads 6500M aqueous dispersion. (1) Art Pearl J-7 aqueous dispersion was obtained in the same manner as in the preparation of the 6500M aqueous dispersion except that 0 g was added.
(3) Preparation of Art Pearl U-800T Water Dispersion Silica composite crosslinked urethane resin fine particles (Art Pearl U-800T manufactured by Negami Kogyo Co., Ltd.) instead of Opto Bead 6500M of the above-mentioned Opto Bead 6500M aqueous dispersion20. (1) Art Pearl U-800T aqueous dispersion was obtained in the same manner as in the preparation of 6500M aqueous dispersion except that 0 g was added.

[Example 1]
(Production of support)
The surface treatment shown below was performed using a JIS A 1050 aluminum plate having a thickness of 0.30 mm and a width of 1030 mm.

<Surface treatment>
In the surface treatment, the following various treatments (a) to (f) were continuously performed. In addition, after each process and water washing, the liquid was drained with the nip roller.

(A) The aluminum plate was etched at a caustic soda concentration of 26 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C. to dissolve the aluminum plate by 5 g / m ² . Thereafter, it was washed with water.

(B) A desmut treatment by spraying was performed with a 1% by mass aqueous solution of nitric acid having a temperature of 30 ° C. (including 0.5% by mass of aluminum ions), and then washed with water.

(C) An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass aqueous nitric acid solution (including 0.5% by mass aluminum ions and 0.007% by mass ammonium ions) at a temperature of 30 ° C. The AC power source was subjected to electrochemical surface roughening using a carbon electrode as a counter electrode, using a trapezoidal rectangular wave alternating current with a time TP of 2 msec until the current value reaches a peak from zero, a duty ratio of 1: 1. Ferrite was used for the auxiliary anode. The current density was 25 A / dm ² at the current peak value, and the amount of electricity was 250 C / cm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Thereafter, it was washed with water.

(D) The aluminum plate was etched by spraying at 35 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, the aluminum plate was dissolved at 0.2 g / m ² , and electricity was obtained using the previous AC. The removal of the smut component mainly composed of aluminum hydroxide generated during chemical roughening and the edge portion of the generated pit were dissolved to smooth the edge portion. Thereafter, it was washed with water.

(E) A desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(F) Anodization was performed for 50 seconds at a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), a temperature of 33 ° C., and a current density of 5 (A / dm ² ). Thereafter, it was washed with water. At this time, the weight of the anodized film was 2.7 g / m ² .
The surface roughness Ra of the aluminum support thus obtained was 0.27 (measuring instrument: Surfcom manufactured by Tokyo Seimitsu Co., Ltd., stylus tip diameter 2 micrometer).

<Undercoat layer>
Next, the following undercoat layer coating solution was applied to the aluminum support 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 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
(Megafac F-780-F Dainippon Ink Chemical Co., Ltd.,
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, and the lithographic printing plate precursor of Example 1 was obtained.
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
[Those obtained in the preparation of the dispersion (1)]
・ Pure water 1364g

[Examples 2 to 5]
In the composition of the coating solution for the protective layer of Example 1, the same applies as in Example 2 except that the type of silica-coated organic resin fine particles and the amount of mica compound added were changed as shown in Table 1 below. 5 lithographic printing plate precursors were obtained.

Example 6
The following protective layer coating solution [2] is applied with a wire bar to the surface of the recording layer formed using the same recording layer coating solution [P-1] as used in Example 1, and applied to a hot-air drying apparatus. And dried at 125 ° C. for 75 seconds to form a first protective layer.
The total coating amount of this protective layer (the coating amount after drying) was 0.5 g / m ² .

<Protective layer coating solution [2]>
・ 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.)
82g
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
・ Pure water 1384g

Next, the following protective layer coating solution [3] is applied to the surface of the first protective layer with a wire bar, and dried at 125 ° C. for 60 seconds with a hot air dryer to form a second protective layer. A lithographic printing plate precursor of Example 6 was obtained.
The total coating amount of this second protective layer (the coating amount after drying) was 1.2 g / m ² .

<Protective layer coating solution [3]>
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 (Nippon Emulsion, Emalex 710) 5g
-Silica composite organic resin fine particle water dispersion (Optobead 6500M water dispersion) 20g
・ Pure water 1384g

Example 7
On the surface of the recording layer formed using the same recording layer coating solution [P-1] as used in Example 1, the following protective layer coating solution [4] was applied with a wire bar, and the hot air drying apparatus was applied. And dried at 125 ° C. for 75 seconds to form a first protective layer.
The total coating amount of this protective layer (the coating amount after drying) was 0.5 g / m ² .

<Protective layer coating solution [4]>
・ 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.)
82g
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
・ Pure water 1384g
Next, the following protective layer coating solution [5] is applied to the surface of the first protective layer with a wire bar, and dried at 125 ° C. for 60 seconds with a hot air dryer to form a second protective layer. A lithographic printing plate precursor of Example 7 was obtained.
The total coating amount of this second protective layer (the coating amount after drying) was 1.2 g / m ² .

<Protective layer coating solution [5]>
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 (Nippon Emulsion, Emalex 710) 5g
・ Silica composite organic resin fine particles (Art Pearl J-7P aqueous dispersion) 20g
・ Pure water 2793g

Example 8
(Preparation of aqueous dispersion of silica-coated fine particles)
(4) Preparation of colloidal silica surface-coated organic particles (MS1) (4-1) Preparation of aqueous dispersion containing acrylate particles Methyl methacrylate 90 parts by mass, methoxypolyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) , Trade name "NK ester M-90G", # 400) 5 parts by mass, 4-vinylpyridine 5 parts by mass, azo polymerization initiator (product name "V50" manufactured by Wako Pure Chemical Industries, Ltd.) 1 part by mass And 400 mass parts of ion-exchange water was prepared to the flask, and it heated up at 70 degreeC, stirring in nitrogen gas atmosphere. The mixture was held for 24 hours while stirring at this temperature. By diluting this reaction mixture with ion-exchanged water, an aqueous dispersion containing 10% by mass of polymethylmethacrylate particles having an average particle diameter of 6 μm and having a functional group having an amino group cation and a polyethylene glycol chain was obtained. . The polymerization yield was 92%.
100 parts by mass of this aqueous dispersion was charged into a flask, 1 part by mass of methyltrimethoxysilane was added thereto, and the mixture was stirred at 40 ° C. for 2 hours. Thereafter, a 1N aqueous nitric acid solution was added to adjust the pH to 2.0 to obtain an aqueous dispersion containing acrylate particles.

(4-2) Preparation of Aqueous Dispersion Containing Colloidal Silica Particles Colloidal silica particles (manufactured by Nissan Chemical Co., Ltd., trade name “Snowtex O”, average primary particle size 12 nm) are dispersed in water, and 1 standard is added to this. By adjusting the pH by adding an aqueous potassium hydroxide solution, an aqueous dispersion having a pH of 8.5 containing 10% by mass of colloidal silica particles was obtained.
(4-3) Preparation of colloidal silica surface-coated organic particles (MS1) The colloidal silica particles obtained in (4-2) above were added to 100 parts by mass of the aqueous dispersion containing the organic particles obtained in (4-1) above. An aqueous dispersion containing particles in which silica particles are adhered to polymethyl methacrylate particles was obtained by gradually adding 50 parts by mass of an aqueous dispersion containing a mixture over 2 hours while stirring and further stirring for 2 hours. .
Next, 2 parts by mass of vinyltriethoxysilane was added to the obtained aqueous dispersion and stirred for 1 hour, and then 1 part by mass of tetraethoxysilane was further added. The temperature was raised to 60 ° C., stirring was continued for 3 hours, and then cooled to room temperature, whereby 10% by mass of colloidal silica surface-coated organic particles having an average particle diameter of 6.5 μmφ (hereinafter referred to as MS1 as appropriate). An aqueous dispersion containing was prepared.
Thereafter, stirring was stopped and the mixture was allowed to stand for 24 hours to sediment MS1, and the supernatant was removed by decantation. Thereafter, 200 parts by weight of pure water was added and allowed to stand for 24 hours, and then the supernatant was removed by decantation. MS1 in a half-wet state was dried by blowing hot air at 70 ° C. to remove 12 parts by weight of a solid.
When the obtained MS1 was observed with a scanning electron microscope, it was confirmed that silica particles adhered to 80% of the surface of the polymethylmethacrylate particles.

(4-4) Aqueous dispersion of silica-coated fine particles 10 parts by weight of MS1 (solid body) obtained in the above (4-3) was used as a mica dispersion (Coop Chemical Co., Ltd. MEB-3L mica solid content 3.2%. ) It was added to 190 parts by weight, and dispersed at 10,000 rpm for 15 minutes using an Ace homogenizer manufactured by Nippon Seiki Seisakusho Co., Ltd. to obtain an MS1 aqueous dispersion.

(Formation of protective layer)
On the surface of the recording layer formed using the same recording layer coating solution [P-1] as used in Example 1, the following protective layer coating solution [4] was applied with a wire bar, and the hot air drying apparatus was applied. And dried at 125 ° C. for 75 seconds to form a first protective layer.
The total coating amount of this protective layer (the coating amount after drying) was 0.5 g / m ² .

<Protective layer coating solution [4]>
・ 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.)
82g
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
・ Pure water 1384g

Next, the following protective layer coating solution [5] is applied to the surface of the first protective layer with a wire bar, and dried at 125 ° C. for 60 seconds with a hot air dryer to form a second protective layer. A lithographic printing plate precursor of Example 8 was obtained.
The total coating amount of this second protective layer (the coating amount after drying) was 1.2 g / m ² .

<Protective layer coating solution [5]>
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 (Nippon Emulsion, Emalex 710) 5g
・ Silica composite organic resin fine particles (MS1 aqueous dispersion) 20g
・ Pure water 2793g

Example 9
The back coat layer coating solution [1] shown below was applied to the back surface of the support used in Example 1 with a wire bar, and dried at 125 ° C. for 60 seconds with a hot air dryer to form a back coat layer made of an organic resin. A lithographic printing plate precursor of Example 9 was obtained in the same manner as in Example 1 except that the formed material was used as a support.
The total coating amount of this back coat layer (the coating amount after drying) was 0.5 g / m ² .

<Backcoat layer coating solution [1]>
・ PR55422 (Sumitomo Bakelite Co., Ltd. (phenol / m-cresol / p-cresol = 5/3/2 average molecular weight 5300) 1.0 g
-Fluorosurfactant (F780F, Dainippon Ink & Chemicals, Inc.) 0.005g
・ Methyl ethyl ketone 25g

[Comparative Example 1]
A lithographic printing plate precursor of Comparative Example 1 was obtained in the same manner as in Example 1 except that the silica composite organic resin fine particles and synthetic mica were not added in the composition of the protective layer coating solution of Example 1.
[Comparative Example 2]
A lithographic printing plate precursor of Comparative Example 2 was obtained in the same manner as in Example 6 except that in the composition of the coating liquid for protective layer of Example 6, the silica composite organic resin fine particles were not added to the uppermost layer.

[Evaluation of planographic printing plate precursor]
(1) Evaluation of sensitivity The output of the obtained lithographic printing plate precursor was changed by 0.15 at logE within a range of resolution 2400 dpi, external drum rotation speed 200 rpm, output 0-8 W, using a Trendsetter 800II Quantum manufactured by Creo. And exposed. 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.
The cyan density of the image area density of the lithographic printing plate obtained by development was measured using a Macbeth reflection densitometer RD-918 and using a red filter equipped with the densitometer. The reciprocal of the exposure necessary to obtain a measured density of 0.9 was used as an index of sensitivity.
The evaluation results were such that the sensitivity of the lithographic printing plate obtained in Example 1 was 100, and the sensitivity of other lithographic printing plates was a relative evaluation thereof. A larger value means higher sensitivity.

(2) Evaluation of scratch resistance A laminate was formed by stacking the obtained lithographic printing plate precursors with no interleaving paper between the 20 lithographic printing plate precursors. This laminated body is shifted from the edge by 5 cm on the planographic printing plate precursor of the present invention that has already been set in the cassette (the stacked 20 plate materials are projected 5 cm outward from the edge of the plate material in the cassette). After stacking, the edges of the 20 protruding plate materials are pushed in horizontally, and the back aluminum support of the 20 stacked bottom plates protects the top lithographic printing plate precursor in the cassette. It was placed in the cassette while rubbing the layer surface. 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 portion 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 sensitivity evaluation. 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 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level.

(3) Evaluation of adhesion between lithographic printing plate precursors 3 lithographic printing plate precursors (10 × 10 cm) obtained were conditioned for 2 hours in an environment of 25 ° C. and 75% RH, and the 3 original plates were directed in the same direction. Were laminated one after another without interleaving of the interleaving paper to obtain a laminate. This laminate was hermetically packaged with kraft paper having an aluminum laminate layer, and left under a 30 ° C. environment for 5 days under a load of 4 kg. About the laminated body after that, the adhesion state of the recording layer side surface (protective layer surface) of the planographic printing plate precursor and the support side surface of the adjacent planographic printing plate precursor was evaluated.
Adhesion between the lithographic printing plate precursors was performed by sensory evaluation of 1 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level. The results are shown in Table 1.

As is clear from Table 1, the planographic printing plate precursors of Examples 1 to 5 and Example 9, that is, a planographic plate in which a protective layer containing silica-coated fine particles and polyvinyl alcohol is provided on a polymerizable negative recording layer. The printing plate precursor and the planographic printing plate precursors of Examples 6 to 8 provided with a protective layer having a laminated structure of a protective layer containing a mica compound and an uppermost protective layer containing silica-coated fine particles are all high. It was found that recording was possible with sensitivity, excellent scratch resistance even without interleaving paper, and adhesion between lithographic printing plate precursors was not observed even after being placed under high humidity.
Further, in contrast to Example 1 and Example 6, those having a laminated structure of a protective layer containing a mica compound and an uppermost protective layer containing silica-coated fine particles showed a further improvement in sensitivity and scratch resistance. I understand that
In contrast, the lithographic printing plate precursors of Comparative Examples 1 and 2 having a protective layer that does not contain silica-coated organic resin fine particles are excellent in sensitivity, but adhere to the lithographic printing plate precursors after being placed under high humidity. It was found that scratch resistance generated when the back surface of the aluminum support and the surface of the protective layer were rubbed was remarkably inferior.

Claims (7)

Negative lithographic printing characterized in that it has a recording layer writable by laser exposure on a support, and a protective layer containing organic resin fine particles whose surface is coated with a hydrophilic polymer and silica on the uppermost layer. Version original edition. Said support is aluminum support, the recording layer, the sensitizing dye, a polymerization initiator, a polymerizable compound, and Ne gas planographic printing plate according to claim 1, characterized in that it contains a binder polymer Original edition.   The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the hydrophilic polymer is polyvinyl alcohol.   The organic resin constituting the organic resin fine particles is at least one selected from the group consisting of polyacrylic acid resins, polyurethane resins, polystyrene resins, polyester resins, epoxy resins, phenol resins, and melamine resins. The lithographic printing plate precursor as claimed in any one of claims 1 to 3, wherein the lithographic printing plate precursor is a resin.   5. The protective layer according to claim 1, wherein the protective layer has a single-layer structure or a multi-layer laminated structure, and at least one layer of the layer structure contains a mica compound. A lithographic printing plate precursor.   The lithographic plate according to any one of claims 1 to 5, wherein the support is an aluminum support and has a back coat layer made of an organic resin on a surface on which the recording layer is not formed. A printing plate master.   A laminate of a lithographic printing plate precursor comprising a plurality of lithographic printing plate precursors according to any one of claims 1 to 6 laminated in direct contact with each other.