JP4486904B2 - Planographic printing plate precursor and planographic printing method - Google Patents

Description

  The present invention relates to a lithographic printing plate precursor and a lithographic printing method using the same. Specifically, based on a digital signal from a computer or the like, for example, a so-called lithographic printing plate precursor capable of direct plate making, which can be directly made by scanning a laser having a wavelength of 300 to 1200 nm, and the lithographic printing plate precursor The present invention relates to a lithographic printing method for directly developing and printing on a printing machine without going through a development processing step.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Normally, after exposing a lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer in the image area remains, and the image recording layer in the non-image area is dissolved with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method of exposing the surface of the hydrophilic support by removing it.

  In the conventional plate-making process of a lithographic printing plate precursor, a step of dissolving and removing the non-image area with a developing solution or the like corresponding to the image recording layer is necessary after exposure. One of the problems is to make the system unnecessary or simplified. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as one of simple plate making methods, an image recording layer that can remove a non-image portion of a lithographic printing plate precursor in a normal printing process is used. A method called on-press development has been proposed in which a part is removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in dampening water, an ink solvent, or an emulsion of dampening water and ink , A method of mechanically removing the image recording layer by contact with rollers or a blanket cylinder of a printing press, cohesion of the image recording layer by penetration of dampening water, ink solvent, etc. There is a method in which after the adhesive force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket cylinder.
In the present invention, unless otherwise specified, the “development process step” means using a device other than a printing press (usually an automatic developing machine) and contacting a liquid (usually an alkaline developer). Refers to the step of removing the laser unexposed portion of the lithographic printing plate precursor and exposing the surface of the hydrophilic support, and “on-press development” refers to a process using a printing machine (typically printing ink and / or It refers to a method and a process for removing the laser unexposed portion of the lithographic printing plate precursor and exposing the surface of the hydrophilic support by contacting with dampening water.

On the other hand, in recent years, digitization techniques for electronically processing, storing, and outputting image information by a computer have become widespread, and various new image output methods corresponding to such digitization techniques are put into practical use. It is becoming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

  Among the lithographic printing plate precursors, the lithographic printing plate precursor capable of scanning exposure is an oleophilic photosensitive resin containing a photosensitive compound capable of generating active species such as radicals and Bronsted acids on a hydrophilic support by laser exposure. Tiers have been proposed and are 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 photosensitive layer to insolubilize it, followed by development processing, thereby developing a negative lithographic printing plate Can be obtained. In particular, a photopolymerization type photosensitive layer containing a photopolymerization initiator excellent in photosensitive speed on a hydrophilic support, an addition-polymerizable ethylenically unsaturated compound, and a binder polymer soluble in an alkali developer, and necessary A lithographic printing plate precursor provided with an oxygen-blocking protective layer in accordance with the printing plate having desirable printing performance due to advantages such as excellent productivity, simple development processing, and good resolution and inking properties. It can be.

Further, as an on-press developable lithographic printing plate, for example, in Patent Document 1, an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support. A planographic printing plate precursor is described. In this Patent Document 1, the above lithographic printing plate precursor is exposed by an infrared laser, and the hydrophobic thermoplastic polymer particles are coalesced by heat to form an image, which is then mounted on a cylinder of a printing press and moistened. It is described that it is possible to perform on-press development with water and / or ink.
In this way, the method of forming an image by merging by simple thermal fusion of fine particles shows good on-press developability, but the image strength (adhesion with the support) is extremely weak and the printing durability is insufficient. Had the problem of being.

Patent Documents 2 and 3 describe lithographic printing plate precursors having an image recording layer (thermosensitive layer) containing microcapsules encapsulating a polymerizable compound on a hydrophilic support.
Patent Document 4 describes a lithographic printing plate precursor in which an image recording layer (photosensitive layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support.
The method using such a polymerization reaction has a feature that the image strength is relatively good because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of polymer fine particles. From a general point of view, all of on-press developability, fine line reproducibility and printing durability are still insufficient and have not been put into practical use.

Further, in Patent Document 5, on-press development is possible in which an image recording layer containing a polymerizable compound and a graft polymer having a polyethylene oxide chain in the side chain or a block polymer having a polyethylene oxide block is provided on a support. A planographic printing plate precursor is described.
However, this technology has good on-press developability, but fine line reproducibility and printing durability are still insufficient.
Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A US Patent Application Publication No. 2003/0064318

  The present invention has been made to remedy the above-mentioned drawbacks of the prior art. That is, an object of the present invention is to enable image recording by laser scanning and on-press development, and to maintain a good on-press developability, while being excellent in fine line reproducibility and printing durability, and a lithographic printing plate precursor, and An object of the present invention is to provide a lithographic printing method using the lithographic printing plate precursor.

The present invention is as follows.
1. On a support, and an image recording layer containing a graft polymer over an infrared absorber having a segment of the main chain and hydrophobic parents aqueous, at least one ethylenically unsaturated bond in the graft polymer molecule the lithographic printing BanHara plate, characterized in that it comprises, mounted on a printing machine after imagewise exposure with a laser, or after the imagewise exposure with a laser, mounted on a printing press, said lithographic printing plate precursor A lithographic printing method in which an oil-based ink and a water-based component are supplied to an image to remove the infrared unexposed portion of the image recording layer and print.

2. The graft polymer The lithographic printing method as described in 1, characterized in that it comprises an ethylenically unsaturated bond as at least one group selected from the group of the following general formula (1) to (3).

(In the formula, X and Y each independently represent an oxygen atom, a sulfur atom or —N—R ^12. Z represents an oxygen atom, a sulfur atom, —N—R ¹² or a phenylene group. R ^{1 to} R ^12. Each independently represents a hydrogen atom or a monovalent substituent.)

3. The image recording layer The lithographic printing method as described in 1 or 2, characterized in that it contains microcapsules.

The present invention is an invention according to the 1 to 3, below, which also describes other matters.

Although the mechanism of action of the on-press development type lithographic printing plate precursor of a polymerization system containing a graft polymer having a hydrophilic group and an ethylenically unsaturated bond is not clear, the presence of the graft polymer causes no image recording layer. In the exposed area, the hydrophilic part is localized to increase the water permeability and improve the on-machine developability, and in the image recording layer exposed area, the area around the localized hydrophilic part is polymerized and cured. It is presumed that an on-press development type lithographic printing plate precursor is obtained. In the present invention, by using a hydrophilic group having a high glass transition temperature, it is possible to improve the mechanical strength of the portion corresponding to the skeleton of the hydrophilic part. It is considered that the printability can be made to a good level while maintaining the on-press developability.

  According to the present invention, a lithographic printing plate precursor having excellent fine line reproducibility and printing durability while being capable of image recording with a laser and maintaining good on-press developability, and lithographic printing using the lithographic printing plate precursor Can provide a method.

The lithographic printing plate precursor according to the present invention is a lithographic printing plate precursor capable of image recording by laser and capable of on-press development, and has a hydrophobic main chain and a hydrophilic segment on the support or hydrophilicity. And an image recording layer containing a graft polymer having a main chain and a hydrophobic segment.
Further, the lithographic printing method of the present invention, the lithographic printing plate precursor is mounted on a printing machine and exposed imagewise with a laser, or after imagewise exposure with a laser, mounted on a printing machine, Oil-based ink and fountain solution are supplied to the lithographic printing plate precursor to remove the laser unexposed portion of the image recording layer and perform printing.
Hereinafter, the components and printing method of the planographic printing plate precursor according to the invention will be described in detail.

(Image recording layer)
The graft polymer of the present invention is a graft polymer having a hydrophobic main chain and a hydrophilic segment, or a hydrophilic main chain and a hydrophobic segment, and the graft polymer has at least an ethylenically unsaturated bond in the molecule. It is characterized by having one. By using this graft polymer, it is possible to provide a lithographic printing plate precursor having excellent fine line reproducibility and printing durability while maintaining good on-press developability.

The synthesis of the graft polymer is basically as follows: 1. Polymerize the branch monomer from the trunk polymer. 2. Link the branch polymer to the trunk polymer. It can be divided into three methods of copolymerizing a branch polymer with a trunk polymer (macromer method).
Any of these three methods can be used to synthesize the graft polymer of the present invention, but “3. Macromer method” is particularly excellent from the viewpoints of manufacturability and ease of synthesis. The synthesis of graft polymers using macromers is described in “New Polymer Experiment 2, Polymer Synthesis and Reaction” published by Kyoritsu Shuppan Co., Ltd., edited by the Society of Polymer Science. It is also described in detail in Yuya Yamashita, et al. The graft polymer of the present invention is a graft polymer having at least one ethylenically unsaturated bond in the molecule and having a hydrophobic main chain and a hydrophilic segment, or a hydrophilic main chain and a hydrophobic segment. . A graft polymer having a hydrophobic main chain and a hydrophilic segment has a hydrophilic segment at the branch, and is easily obtained by copolymerization of a hydrophilic macromer and a hydrophobic monomer. A graft polymer having a segment has a hydrophobic segment at a branch, and can be easily obtained by copolymerization of a hydrophobic macromer and a hydrophilic monomer constituting a trunk. The graft polymer of the present invention is further characterized in that an ethylenically unsaturated bond is introduced into the molecule. Hereinafter, the graft polymer of the present invention will be described more specifically.

<Description of Graft Polymer Having Hydrophobic Main Chain and Hydrophilic Segment>
(Hydrophilic macromer)
The hydrophilic segment of the hydrophilic macromer (also referred to as macromonomer) used in the present invention includes at least one amide group-containing monomer, an acid group-containing monomer, an alkali metal salt of an acid group-containing monomer, It is desirable that the polymer has a known hydrophilic monomer such as a quaternary ammonium salt-containing monomer and a hydroxyl group-containing monomer, and contains 50 mol% or more of the above monomer units.
The hydrophilic macromer used in the present invention is obtained by bonding a polymerizable group to the end of this hydrophilic segment.

  Specific examples of the amide group-containing monomer include acrylamide-t-butylsulfonic acid, N, N-dimethylacrylamide, acrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N -Methylol acrylamide, N-vinyl pyrrolidone, N-vinyl acetamide, etc. are mentioned.

  Examples of the acid group-containing monomer include methacrylic acid, acrylic acid, styrene sulfonic acid and the like. Examples of alkali metal salts of acid group-containing monomers include sodium salt of methacrylic acid, sodium salt of acrylic acid, sodium styrenesulfonate, sodium ethoxymethacrylate sulfonate, sodium ethoxyacrylate sulfonate, and mono-2-acryloyloxyethyl acid phosphate. And the sodium salt thereof.

  Examples of the quaternary ammonium base-containing monomer include hydroxyethyltrimethylammonium methacrylate methacrylate, hydroxypropyltrimethylammonium methacrylate methacrylate, and hydroxyethyltrimethylammonium chloride acrylate.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and 2,3-dihydroxypropyl methacrylate.

  Hydrophobic monomers used to adjust the hydrophilicity of the hydrophilic segment include acrylic esters, methacrylic acids, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide And the like, and known hydrophobic monomers.

  Specific examples of acrylic esters include methyl acrylate, ethyl acrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butyl acrylate, chloroethyl acrylate, cyclohexyl acrylate, allyl Acrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydroxyphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate, Examples include 2- (hydroxyphenylcarbonyloxy) ethyl acrylate It is.

  Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-, i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, Chloroethyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, benzyl methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, hydroxyphenyl methacrylate, chlorophenyl Methacrylate, sulfa Examples include moylphenyl methacrylate and 2- (hydroxyphenylcarbonyloxy) ethyl methacrylate.

  Specific examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate and the like.

  Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, propyl styrene, cyclohexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, methoxy styrene, dimethoxy styrene. Chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, carboxystyrene and the like.

  The preferred molecular weight of these hydrophilic macromers is in the range of 400 to 100,000, more preferably 1000 to 50,000, and particularly preferably 1500 to 20,000. Within the range of this molecular weight, the effect of the present invention can be exhibited without impairing the polymerizability with the copolymer monomer forming the trunk.

(Hydrophobic monomer)
Particularly useful hydrophobic monomers that copolymerize with hydrophilic macromers include known acrylic esters, methacrylic acids, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide, and the like. Examples include hydrophobic monomers. A graft polymer can be synthesized by appropriately selecting one or two or more of these monomers.

  Specific examples of acrylic esters include methyl acrylate, ethyl acrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, Dodecyl acrylate, chloroethyl acrylate, cyclohexyl acrylate, allyl acrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydroxyphenyl Acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate Rate, 2- (hydroxyphenylcarbonyloxy) ethyl acrylate and the like.

  Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-, i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, Dodecyl methacrylate, chloroethyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, benzyl methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, hydroxyphenyl Methacrylate, chlorophenyl Examples include methacrylate, sulfamoylphenyl methacrylate, 2- (hydroxyphenylcarbonyloxy) ethyl methacrylate, and the like.

  Specific examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate and the like.

Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, propyl styrene, cyclohexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, methoxy styrene, dimethoxy styrene. Chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, carboxystyrene and the like.

The hydrophobic monomer may further have a substituent. As the substituent, a monovalent nonmetallic atomic group excluding hydrogen is used. Preferred examples include halogen atoms (-F, -Br, -Cl, -I), hydroxyl groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, N-alkylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, ア ル キ ル -alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkyl Carbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-aryl Acylamino 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-alkylureate group, N', N'-dialkyl- N-arylureido group, N′-aryl-Ν-alkylureido group, N′-aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl- N-arylureido group, N′-alkyl-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, 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, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO ₃ H) and its conjugated base group (hereinafter referred to as sulfonato group), a Coxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N -Alkyl-N-arylsulfamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonate group), dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl Phosphono group (—PO ₃ (aryl) ₂ ), alkylaryl phosphono group (—PO ₃ (Alkyl) (aryl)), a monoalkylphosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkylphosphonate group), a monoarylphosphono group (—PO ₃ H (aryl)). )) And its conjugate base group (hereinafter referred to as aryl phosphonate group), phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonatooxy group), dialkylphosphonooxy group _{(-OPO 3 (alkyl) 2)} , diaryl phosphonooxy group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphonooxy group (-OPO (alkyl) (aryl) ), monoalkyl phosphonooxy group (- OPO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), Mo Aryl phosphonooxy group (-OPO ₃ H (aryl)) and its conjugated base group (hereinafter referred to as aryl phosphite Hona preparative group), Moruhoruno group, a cyano group, a nitro group, an aryl group, an alkenyl group, an alkynyl group include It is done.

Specific examples of the alkyl group in these substituents include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, s-butyl group, t -Butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group and the like can be mentioned. Among these, a hydrogen atom, a methyl group, and an ethyl group are more preferable from the viewpoints of effects and availability. Specific examples of the aryl group include phenyl group, biphenyl group, naphthyl group, tolyl 2 group, xylyl group, mesityl group, cumenyl group, chlorophenyl group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, Ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group , Ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, phenyl group, cyanophenyl group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl , Can be exemplified phosphonophenyl phenyl group. Examples of alkenyl groups include vinyl, 1-propenyl, 1-butenyl, cinnamyl, 2-chloro-1-ethenyl, etc. Examples of alkynyl include ethynyl, 1-butenyl, A propynyl group, a 1-butynyl group, a trimethylsilylethynyl group, etc. are mentioned. Examples of G ₁ in the acyl group (G ₁ CO—) include hydrogen and the above alkyl groups and aryl groups.

  Among these substituents, more preferred are halogen atoms (—F, —Br, —Cl, —I), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, N-alkylamino groups, N, N-dialkyls. Amino group, acyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, acylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, sulfo group, sulfonate group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfamoy Group, N-alkyl-N-arylsulfamoyl group, phosphono group, phosphonate group, dialkyl phosphono group, diaryl phosphono group, monoalkyl phosphono group, alkyl phosphonate group, monoaryl phosphono group, aryl phosphonate group Group, phosphonooxy group, phosphonatooxy group, aryl group, and alkenyl group.

On the other hand, examples of the alkylene group in the substituted alkyl group include divalent organic residues obtained by removing any one of the hydrogen atoms on the alkyl group having 1 to 20 carbon atoms. Can be a straight chain having 1 to 12 carbon atoms, a branched chain having 3 to 12 carbon atoms, and a cyclic alkylene group having 5 to 10 carbon atoms. Preferable specific examples of the substituted alkyl group obtained by combining the substituent and the alkylene group include chloromethyl group, bromomethyl group, 2-chloroethyl group, trifluoromethyl group, methoxymethyl group, methoxyethoxyethyl group, allyl group. Oxymethyl group, phenoxymethyl group, methylthiomethyl, tolylthiomethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamoyloxyethyl group, N- Phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxyethyl group, 2-oxypropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxy Carbonyl butyl group, chlorophenoxy carbonyl methyl group,
Carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfophenyl) carbamoylmethyl group, sulfobutyl group, Sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group, N-methyl-N- (phosphonophenyl) sulfur Famoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobutyl group, tolylphosphonohexyl group, tolylphosphonatohexyl group, Phosphonoki Propyl group, phosphonatooxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methylbenzyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 2 -Butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group and the like can be mentioned.

<Description of Graft Polymer Having Hydrophilic Main Chain and Hydrophobic Segment>
(Hydrophobic macromer)
The hydrophobic segment of the hydrophobic macromer (also referred to as macromonomer) used in the present invention includes acrylic esters, methacrylic esters, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic Examples include those obtained by polymerizing one kind selected from known hydrophobic monomers such as acid imides, and those obtained by copolymerizing two or more kinds. The hydrophobic macromer of the present invention is obtained by attaching a polymerizable group to the end of this hydrophobic segment.

  Specific examples of the hydrophobic monomer and the substituents it can have include the monomers described in the description of (hydrophobic monomer) in the present specification.

  The preferred molecular weight of these hydrophobic macromers is in the range of 400 to 100,000, more preferably 1000 to 50,000, and particularly preferably 1500 to 20,000. Within the range of this molecular weight, the effect of the present invention can be exhibited without impairing the polymerizability with the copolymerization monomer forming the main chain.

(Hydrophilic monomer)
Hydrophilic monomers copolymerized with hydrophobic macromers include amide group-containing monomers, acid group-containing monomers, alkali metal salts of acid group-containing monomers, quaternary ammonium salt-containing monomers, hydroxyl group-containing Known hydrophilic monomers such as monomers may be mentioned. A graft polymer can be synthesized by copolymerizing one or more selected from these hydrophilic monomers with one or more hydrophobic monomers.

  Specific examples of the amide group-containing monomer include 2-acrylamide-2-methylpropanesulfonic acid, N, N-dimethylacrylamide, acrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N-methylol acrylamide etc. are mentioned.

  Specific examples of the acid group-containing monomer, the quaternary ammonium base-containing monomer and the hydroxyl group-containing monomer include the acid group-containing monomer in the description of the (hydrophilic macromer) in the present specification, the fourth The same thing as the specific example of a quaternary ammonium base containing monomer and a hydroxyl-containing monomer can be mentioned.

  In the present invention, the hydrophilicity of the main chain can be appropriately adjusted by copolymerizing a hydrophobic monomer in addition to the hydrophilic monomer to the main chain of the graft polymer. Specific examples of the hydrophobic monomer include monomers described in the description of (hydrophobic monomer) in the present specification. The introduction amount of the hydrophobic monomer in the main chain is preferably 0 to 50 mol%, more preferably 0 to 30 mol%.

<Introduction of ethylenically unsaturated bond>
In the present invention, in order to improve the film properties and on-press developability of the image recording layer, it is essential that the graft polymer has at least one ethylenically unsaturated bond. The ethylenically unsaturated bond preferably has at least one group selected from the group of the following general formulas (1) to (3).

(In the formula, X and Y each independently represent an oxygen atom, a sulfur atom or —N—R ^12. Z represents an oxygen atom, a sulfur atom, —N—R ¹² or a phenylene group. R ^{1 to} R ^12. Each independently represents a hydrogen atom or a monovalent substituent.)

In the general formula (1), R ^{1 to} R ³ each independently represents a monovalent substituent. For example, R ¹ is a hydrogen atom, a monovalent organic group such as an alkyl which may have a substituent. Group, and the like. Among them, a hydrogen atom, a methyl group, a methylalkoxy group, and a methyl ester group are preferable. R ² and R ³ may each independently have a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyano group, or a substituent. Alkyl group, aryl group which may have a substituent, alkoxy group which may have a substituent, aryloxy group which may have a substituent, alkylamino group which may have a substituent, substituted An arylamino group that may have a group, an alkylsulfonyl group that may have a substituent, an arylsulfonyl group that may have a substituent, and the like. Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group An alkyl group which may have a substituent and an aryl group which may have a substituent are preferable. Here, examples of the substituent that can be introduced include a methoxycarbonyl group, an ethoxycarbonyl group, an isopropyloxycarbonyl group, a methyl group, an ethyl group, and a phenyl group. X represents an oxygen atom, a sulfur atom, or —NR ^12, and examples of R ¹² include an alkyl group that may have a substituent.

In the general formula (2), R ^{4 to} R ⁸ each independently represent a monovalent substituent, such as a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group. Group, nitro group, cyano group, alkyl group which may have a substituent, aryl group which may have a substituent, alkoxy group which may have a substituent, aryl which may have a substituent An oxy group, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, an arylsulfonyl group which may have a substituent Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, an alkyl group which may have a substituent, and an aryl group which may have a substituent are preferable. Examples of the substituent that can be introduced include those listed in the general formula (1).
Y represents an oxygen atom, a sulfur atom, or N—R ¹² . Examples of R ¹² include those listed in general formula (1).

In the general formula (3), R ^{9 to} R ¹¹ each independently represents a monovalent substituent, such as a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group. Group, nitro group, cyano group, alkyl group which may have a substituent, aryl group which may have a substituent, alkoxy group which may have a substituent, aryl which may have a substituent An oxy group, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, an arylsulfonyl group which may have a substituent Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, an alkyl group which may have a substituent, and an aryl group which may have a substituent are preferable. Here, as a substituent, what was mentioned in General formula (1) is illustrated similarly. Z represents an oxygen atom, a sulfur atom, —N—R ¹² or a phenylene group. Examples of R ¹² include those listed in general formula (1).

  Among the graft polymers used in the lithographic printing plate precursor according to the invention, the compound having a group represented by (1) can be produced by at least one of the synthesis methods 1) and 2) shown below. .

Synthesis method 1)
At the time of synthesizing the hydrophilic macromer and the hydrophobic macromer, one or more radically polymerizable compounds represented by the following general formula (4) or (5) are added and polymerized to synthesize a macromonomer. Radical polymerizability represented by the following general formula (4) or (5) after copolymerization with a hydrophilic monomer or hydrophobic monomer, or upon copolymerization of a macromonomer with the hydrophilic monomer or hydrophobic monomer. A method in which one or more compounds are added and polymerized, followed by a base treatment to cause elimination reaction to remove X ¹ and Z ¹ in the formula to obtain a desired graft polymer.

In the above formula, X ¹ and Z ¹ are leaving groups that are removed by the elimination reaction, and the elimination reaction referred to here means that Z ¹ is extracted by the action of a base and X ¹ is eliminated. is there. X ¹ is preferably eliminated as an anion and Z ¹ as a cation.
Specific examples of X ¹ include halogen atoms, sulfonic acid groups, sulfinic acid groups, carboxylic acid groups, cyano groups, ammonium groups, azide groups, sulfonium groups, nitro groups, hydroxyl groups, alkoxy groups, phenoxy groups, thioalkoxy groups, An oxonium group is mentioned as an example, and a halogen atom, a sulfonic acid group, an ammonium group, and a sulfonium group are preferable. Among these, a chlorine atom, a bromine atom, an iodine atom, an alkylsulfonic acid group, and an arylsulfonic acid group are particularly preferable. Examples of preferred alkyl sulfonic acid groups include methane sulfonic acid groups, ethane sulfonic acid groups, 1-propane sulfonic acid groups, isopropyl sulfonic acid groups, 1-butane sulfonic acid groups, 1-octyl sulfonic acid groups, and 1-hexadecane sulfone. Acid group, trifluoromethanesulfonic acid group, trichloromethanesulfonic acid group, 2-chloro-1-ethanesulfonic acid group, 2,2,2-trifluoroethanesulfonic acid group, 3-chloropropanesulfonic acid group, perfluoro-1 -Butanesulfonic acid group, perfluoro-1-octanesulfonic acid group, 10-camphorsulfonic acid group, benzylsulfonic acid group. Examples of preferred aryl sulfonic acid groups include benzene sulfonic acid groups, trans-beta-styrene sulfonic acid groups, 2-nitrobenzene sulfonic acid groups, 2-acetylbenzene sulfonic acid groups, and 3- (trifluoromethyl) benzene sulfonic acid groups. 3-nitrobenzenesulfonic acid group, 4-nitrobenzenesulfonic acid group, p-toluenesulfonic acid group, 4-tert-butylbenzenesulfonic acid group, 4-fluorobenzenesulfonic acid group, 4-chlorobenzenesulfonic acid group, 4-bromo Benzenesulfonic acid group, 4-iodobenzenesulfonic acid group, 4-methoxybenzenesulfonic acid group, 4- (trifluoromethoxy) benzenesulfonic acid group, 2,5-dichlorobenzenesulfonic acid group, 2-nitro-4- ( Trifluoromethyl) -benzenesulfonic acid group, 4 Chloro-3-nitrobenzenesulfonic acid group, 2,4-dinitrobenzenesulfonic acid group, 2-mesitylenesulfonic acid group, 2,4,6-triisopropylbenzenesulfonic acid group, pentafluorobenzenesulfonic acid group, 1-naphthalenesulfone group An acid group and 2-naphthalenesulfonic acid group are mentioned.

Specific examples of Z ¹ include a hydrogen atom, a halogen atom, an ammonium group, a sulfonium group, a phosphonium group, and an oxonium group, and among them, a hydrogen atom is particularly preferable. Proton is extracted by the action of the base, and X ¹ is eliminated.
In the present invention, the most preferred combination is that X ¹ is a halogen atom and Z ¹ is a hydrogen atom. In this case, X ¹ is released as an anion and Z ¹ is released as a cation.
In the general formulas (4) and (5), R ¹³ includes a hydrogen atom or an alkyl group which may have a substituent, among which a hydrogen atom, a methyl group, a methylalkoxy group, or a methyl ester group preferable. Q represents an oxygen atom, —NH—, or NR ¹⁴ — (wherein R ¹⁴ represents an alkyl group which may have a substituent). A represents a divalent organic linking group. R < ¹ > -R < ³ > and X are synonymous with the case of General formula (1)-(3).

  In the general formulas (4) and (5), the divalent organic linking group represented by A is 1 to 60 carbon atoms, 0 to 10 nitrogen atoms, 0 to 50 carbon atoms. It consists of oxygen atoms, 1 to 100 hydrogen atoms, and 0 to 20 sulfur atoms. More specific examples of the linking group include those formed by combining the following structural units.

(Base used for elimination reaction)
In the method for producing a graft polymer having at least one group represented by the general formula (1) in the side chain, which is preferably used in the present invention, an elimination reaction is caused in a specific functional group by base treatment, and X in the formula It is characterized in that ¹ and Z ¹ are removed to obtain a radical reactive group, and the base used in this case includes alkali metal hydrides, hydroxides or carbonates, organic amine compounds, metals Preferred examples include alkoxide compounds.
Preferred examples of alkali metal hydrides, hydroxides or carbonates include sodium hydride, calcium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium carbonate, sodium carbonate, Examples include potassium hydrogen carbonate and sodium hydrogen carbonate.
Preferable examples of the organic amine compound include trimethylamine, triethylamine, diethylmethylamine, tributylamine, triisobutylamine, trihexylamine, trioctylamine, N, N-dimethylcyclohexylamine, N, N-diethylcyclohexylamine, N- Methyldicyclohexylamine, N-ethyldicyclohexylamine, pyrrolidine, 1-methylpyrrolidine, 2,5-dimethylpyrrolidine, piperidine, 1-methylpiperidine, 2,2,6,6-tetramethylpiperidine, piperazine, 1,4-dimethyl Piperazine, quinuclidine, 1,4-diazabicyclo [2,2,2] -octane, hexamethylenetetramine, morpholine, 4-methylmorpholine, pyridine, picoline, 4-dimethylaminopyridine, Cytidine, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU), N, N'-dicyclohexylcarbodiimide (DCC), diisopropylethylamine, Schiff base, and the like.
Preferable examples of the metal alkoxide compound include sodium methoxide, sodium ethoxide, potassium t-butoxide and the like. These bases may be used alone or in combination of two or more.

  In the elimination reaction in the present invention, as a solvent used when adding a base, for example, ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, propanol, butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, toluene, ethyl acetate, methyl lactate, ethyl lactate , Water and the like. These solvents may be used alone or in combination of two or more.

The amount of the base used may be equal to or less than the equivalent or greater than or equal to the amount of the specific functional group in the compound.
Moreover, when an excess base is used, it is also a preferable form to add an acid or the like for the purpose of removing the excess base after the elimination reaction. Examples of acids include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid and perchloric acid, acetic acid, fluoroacetic acid, trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid. Organic acids are examples.
The temperature condition in the elimination reaction may be any of room temperature, cooling, and overheating. As preferable temperature conditions, it is the range of -20-100 degreeC.

  Examples of the radical polymerizable compound represented by the general formulas (4) and (5) include the following compounds, but are not limited thereto.

Synthesis method 2)
After synthesizing the above-mentioned macromer with a radical polymerizable compound having one or more kinds of functional groups and synthesizing a graft polymer, the functional group of the graft polymer is reacted with a compound having a structure represented by the general formula (6). To obtain a desired graft polymer.

R < ¹ > -R < ³ > of General formula (6) is synonymous with the case of General formula (1).

Examples of the functional group of the radical polymerizable compound having a functional group used for the synthesis of the graft polymer in the synthesis method 2) include a hydroxyl group, a carboxyl group, a carboxylic acid halide group, a carboxylic acid anhydride group, an amino group, and a halogenated alkyl group. , Isocyanate groups, epoxy groups and the like. Radical polymerizable compounds having these functional groups include 2 monohydroxyl acrylate, 2 monohydroxyl methacrylate, 4 monohydroxybutyl acrylate, 4 monohydroxybutyl methacrylate, acrylic acid, methacrylic acid, acrylic acid chloride, methacrylic acid chloride. Methacrylic anhydride, N, N-dimethyl-2-aminoethyl methacrylate, 2-chloroethyl methacrylate, ethyl 2-isocyanate, glycidyl acrylate, grindyl methacrylate, and the like. After synthesizing one or more radically polymerizable compounds and a macromonomer and further copolymerizing with another radically polymerizable compound as necessary to synthesize a trunk polymer compound, the general formula (6) A desired polymer compound can be obtained by reacting a compound having a group represented by the formula: Here, examples of the compound having a group represented by the general formula (6) include the compounds mentioned as examples of the radical polymerizable compound having the above-described functional group.

  The specific polymer compound having a group represented by the general formula (2) in the graft polymer preferably used in the present invention can be produced by at least one of the synthesis methods 3) and 4) shown below.

Synthesis method 3)
At the time of the macromer synthesis, one or more radically polymerizable compounds having an unsaturated group represented by the general formula (2) and an ethylenically unsaturated group further enriched in addition polymerization than the unsaturated group are added. A method of synthesizing a macromer to copolymerize the macromer with a hydrophilic monomer or a hydrophobic monomer to obtain a graft polymer, or at the time of copolymerizing the macromer with a hydrophilic monomer or a hydrophobic monomer, the general formula (2) A method of obtaining a graft polymer by adding a radical polymerizable compound having an unsaturated group represented by the formula (1) and an ethylenically unsaturated group having a higher addition polymerizability than the unsaturated group and copolymerizing the radical polymerizable compound. This method uses a compound having a plurality of ethylenically unsaturated groups having different addition polymerization properties in one molecule.

  Examples of the radically polymerizable compound having an unsaturated group represented by the single-stage formula (2) and an ethylenically unsaturated group having a higher addition polymerizability than the unsaturated group include allyl acrylate, allyl methacrylate, 2- Examples include allyloxyethyl acrylate, propargyl acrylate, propargyl methacrylate, N-allyl acrylate, N-allyl methacrylate, N, N-diallyl acrylate, N, N monodiallyl methacrylate, allyl acrylamide, and allyl methacrylamide. Examples of the polymer compound obtained by polymerizing one or more radically polymerizable compounds having a functional group include those shown in the aforementioned synthesis method 2).

Synthesis method 4)
At the time of macromer synthesis, a radical polymerizable compound having a functional group is added and copolymerized to synthesize a macromer, and then the macromonomer and a hydrophilic monomer or a hydrophobic monomer are copolymerized to synthesize a graft polymer, or the macromer A graft polymer is synthesized by adding a radically polymerizable compound having a functional group at the time of copolymerization with a hydrophilic monomer or a hydrophobic monomer to synthesize the graft polymer, and then the graft polymer is represented by the following general formula (7) A method of introducing a group represented by the general formula (2) by reacting a compound having a structure.

R < ⁴ > -R < ⁸ > of General formula (7) is synonymous with the case of General formula (2).

  Examples of the compound having the structure represented by the general formula (7) include allyl alcohol, allylamine, diallylamine, 2-allyloxyethyl alcohol, 2-chloro-1-butene, and allyl isocyanate.

  The specific polymer compound having a group represented by the general formula (3) in the side chain, which is preferably used in the present invention, can be produced by at least one of the synthesis methods 5) and 6) shown below.

Synthesis method 5)
At the time of synthesizing the macromer, one or more radically polymerizable compounds having an unsaturated group represented by the general formula (3) and an ethylenically unsaturated group further enriched in addition polymerization than the unsaturated group were added. A method of synthesizing a macromer and copolymerizing the macromer with a hydrophilic monomer or a hydrophobic monomer to obtain a graft polymer, or at the time of copolymerizing the macromer with a hydrophilic monomer or a hydrophobic monomer, the general formula (3) A method of obtaining a graft polymer by adding a radically polymerizable compound having an unsaturated group represented by the formula (1) and an ethylenically unsaturated group having a higher addition polymerizability than the unsaturated group and copolymerizing the radically polymerizable compound. This method uses a compound having a plurality of ethylenically unsaturated groups having different addition polymerization properties in one molecule.

  Examples of the radically polymerizable compound having an unsaturated group represented by the general formula (3) and an ethylenically unsaturated group having a higher addition polymerizability than the unsaturated group include vinyl acrylate, vinyl methacrylate, and 2-phenyl. Examples include vinyl acrylate, 2-phenylvinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, vinyl acrylamide, vinyl methacrylamide and the like. Examples of the polymer compound obtained by polymerizing one or more radically polymerizable compounds having a functional group include those shown in the aforementioned synthesis method 2).

Synthesis method 6)
At the time of macromer synthesis, a radical polymerizable compound having a functional group is added and copolymerized, and then a graft polymer is synthesized, and the graft polymer is reacted with a compound having a structure represented by the following general formula (8). In the method of introducing the group represented by the formula (3) or the copolymerization of the macromonomer and the hydrophilic monomer or the hydrophobic monomer, a radically polymerizable compound having a functional group is added and copolymerized to obtain a graft polymer. A method of introducing a group represented by the general formula (3) by reacting the graft polymer with a compound having a structure represented by the following general formula (8) after the synthesis.

R < ⁹ > -R < ¹¹ > of General formula (8) is synonymous with the case of General formula (3).

  Examples of the compound having the structure represented by the general formula (8) include 2-hydroxyethyl monovinyl ether, 4-hydroxybutyl monovinyl ether, diethylene glycol monovinyl ether, and 4-chloromethylstyrene.

10-90 mass% is preferable, and, as for the hydrophilic macromer content rate in the graft polymer of this invention, More preferably, it is 15-85 mass%.
Further, the mass average molecular weight of the graft polymer of the present invention is preferably 5,000 to 1,000,000, more preferably 10,000 to 500,000.

  The content of the graft polymer of the present invention in the image recording layer is preferably 10 to 90% by mass, more preferably 15 to 80% by mass, based on the total solid content of the image recording layer, and 20 -70 mass% is more preferable. Within these ranges, the effects of the present invention that improve both the on-press developability, fine line reproducibility and printing durability can be obtained.

<Infrared absorber>
When forming an image of the lithographic printing plate precursor according to the present invention with a laser that emits infrared light of 760 to 1200 nm, for example, it is usually essential to use an infrared absorber. The infrared absorber has a function of converting absorbed infrared rays into heat. With the heat generated at this time, a polymerization initiator (radical generator) described later is thermally decomposed to generate radicals. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

  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.

  Examples of preferable dyes include cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, Methine dyes described in JP-A Nos. 58-181690 and 58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc., squarylium dyes described in JP-A-58-112792, etc., British Patent No. And cyanine dyes described in the specification of 434,875.

Further, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also preferred. ) Pyrylium salt, 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, 59-84249, 59-146063, 59-146061, pyranyl compounds described in JP-A-59-216146, cyanine dyes described in US Pat. It is disclosed in the pentamethine thiopyrylium salt, etc. described in Japanese Patent No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds are also preferably used. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
Other preferable examples of the infrared absorbing dye of 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 preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (I).

In general formula (I), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.

Xa ^- the Za described later ^- is defined as for, 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.

R ¹ and R ² each independently represents 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. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (I) has an anionic substituent in its structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ions and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (I) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. be able to.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  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 Application of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle diameter of the pigment is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 1 μm, and particularly preferably in the range of 0.1 to 1 μm. Within this range, good stability of the pigment dispersion in the image recording layer coating solution and good uniformity of the image recording layer can be obtained.

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

These infrared absorbers may be added to the same layer as the other components, or may be added to another layer provided, but when a negative planographic printing plate precursor is prepared, image recording is performed. It is preferable to add such that the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the layer is in the range of 0.3 to 1.2 by reflection measurement, more preferably 0.4 to 1. 1 range. Within this range, a uniform polymerization reaction proceeds in the depth direction of the image recording layer, and good film strength of the image area and adhesion to the support can be obtained.
The absorbance of the image recording layer can be adjusted by the amount of infrared absorber added to the image recording layer and the thickness of the image recording layer. The absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

<Polymerization initiator>
As the polymerization initiator used in the image recording layer of the present invention, various photopolymerization initiators known in patents, literatures, etc., or a combination system of two or more photopolymerization initiators depending on the wavelength of the light source used ( Photopolymerization initiation system) can be appropriately selected and used.

In the case where a blue semiconductor laser, Ar laser, second harmonic of an infrared semiconductor laser, or SHG-YAG laser is used as a light source, various photopolymerization initiators (systems) have been proposed. Certain photoreducible dyes described in US Pat. No. 850,445, such as rose bengal, eosin, erythrosine, etc., or a combination of a dye and an initiator, such as a complex initiator system of a dye and an amine (Japanese Patent Publication No. 44) -20099), a combination system of hexaarylbiimidazole, a radical generator and a dye (Japanese Patent Publication No. 45-37377), a system of hexaarylbiimidazole and p-dialkylaminobenzylidene ketone (Japanese Patent Publication No. 47-2528). JP, 54-155292), a system of a cyclic cis-α-dicarbonyl compound and a dye (JP 48-8) 183), a system of a cyclic triazine and a merocyanine dye (Japanese Patent Laid-Open No. 54-151024), a system of 3-ketocoumarin and an activator (Japanese Patent Laid-Open No. 52-112682, Japanese Patent Laid-Open No. 58-15503) , Biimidazole, styrene derivative, thiol system (JP 59-140203 A), organic peroxide and dye system (JP 59-1504 A, JP 59-140203 JP, JP JP-A 59-189340, JP-A 62-174203, JP-B 62-1641, US Pat. No. 4,766,055), a system of a dye and an active halogen compound (JP-A 63-1718105, JP-A-63-258903, JP-A-3-264771, etc.), a system of a dye and a borate compound (JP-A-62-143044, Japanese Laid-Open Patent Publication No. 62-15242, Japanese Laid-Open Patent Publication No. 64-13140, Japanese Laid-Open Patent Publication No. 64-13141, Japanese Laid-Open Patent Publication No. 64-13142, Japanese Laid-Open Patent Publication No. 64-13143, Japanese Laid-Open Patent Publication No. 64-13144. JP-A 64-17048, JP-A 1-222903, JP-A 1-298348, JP-A 1-138204, etc.), a system comprising a dye having a rhodanine ring and a radical generator ( JP-A-2-17943, JP-A-2-244050), titanocene and 3-ketocoumarin dye system (JP-A 63-221110), titanocene and xanthene dye, addition polymerization containing amino group or urethane group A combination of possible ethylenically unsaturated compounds (JP-A-4-221958, JP-A-4-219756), Tanosen and system specific merocyanine dye (JP-A-6-295061), a dye system with titanocene and benzopyran ring (JP-A-8-334897 JP), and the like.

  In the image recording layer of the lithographic printing plate precursor according to the invention, a particularly preferred photopolymerization initiator (system) contains at least one titanocene. The titanocene compound used as a photopolymerizable initiator (system) in the present invention may be any titanocene compound that can generate an active radical when irradiated with light in the presence of a sensitizing dye described later. For example, JP 59-152396 A, JP 61-151197 A, JP 63-41483 A, JP 63-41484 A, JP 2-249 A, and JP 2 -291, JP-A-3-27393, JP-A-3-12403, and JP-A-6-41170 can be appropriately selected and used.

  More specifically, di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,3,4,5 , 6-pentafluorophen-1-yl (hereinafter also referred to as “T-1”), di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di- -Cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-cyclo Pentadienyl-Ti-bis-2,4-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl Di-methylcyclopentadie Ru-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclo And pentadienyl) -bis (2,6-difluoro-3- (pyr-1-yl) phenyl) titanium (hereinafter also referred to as “T-2”).

  These titanocene compounds can be further subjected to various chemical modifications for improving the characteristics of the image recording layer. For example, bonding with sensitizing dyes, addition polymerizable unsaturated compounds and other radical generating parts, introduction of hydrophilic sites, compatibility improvement, introduction of substituents to suppress crystal precipitation, introduction of substituents to improve adhesion A method such as polymerization can be used.

The use method of these titanocene compounds can be arbitrarily set as appropriate according to the performance design of the lithographic printing plate precursor as in the above-described addition polymerizable compound. For example, the compatibility with the image recording layer can be enhanced by using two or more kinds in combination. A larger amount of the photopolymerization initiator such as the titanocene compound is usually advantageous in terms of photosensitivity, and is 0.5 to 80 parts by mass, preferably 1 to 100 parts by mass of the non-volatile component of the image recording layer. Sufficient photosensitivity is obtained by using in the range of -50 mass parts. On the other hand, when used under a white light such as yellow, it is preferable that the amount of titanocene used is small in terms of fogging by light near 500 nm, but the amount of titanocene used is 6 parts by mass in combination with a sensitizing dye. Thereafter, sufficient photosensitivity can be obtained even when the content is further reduced to 1.9 parts by mass or less, and further to 1.4 parts by mass or less.

As the thermal polymerization initiator used in the present invention for initiating and advancing the curing reaction of the addition polymerizable compound, a thermal decomposition type radical generator that decomposes by heat to generate radicals is useful. Such radical generators are used in combination with the above-mentioned infrared absorbers, and when the infrared laser is irradiated, the infrared absorbers generate heat and generate radicals by the heat. Recording is possible by combining these. It becomes.
Examples of the radical generator include onium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazides, oxime ester compounds, triaryl monoalkylborate compounds, etc. Or an oxime ester compound has high sensitivity and is preferable. Below, the onium salt which can be used suitably as a polymerization initiator in this invention is demonstrated. Preferred onium salts include iodonium salts, diazonium salts, and sulfonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators. The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (A) to (C).

In general formula (A), Ar ¹¹ and Ar ¹² 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 ¹¹⁻ represents a counter ion selected from the group consisting of a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a carboxylate ion, and a sulfonate ion, preferably a perchlorate ion, Hexafluorophosphate ions, carboxylate ions, and aryl sulfonate ions.

In the general formula (B), Ar ²¹ 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 ^21- represents a counter ion having the same ^meaning as Z ^11- .

In the general formula (C), R ³¹ , R ³² and R ³³ 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 ^31- represents a counter ion having the same ^meaning as Z ^11- .

  In the present invention, specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) include those described in JP-A-2001-133696. In the present invention, onium salts represented by general formula (A) ([OI-1] to [OI-10]) and onium salts represented by general formula (B) ([ON] which can be suitably used in the present invention are shown below. -1] to [ON-5]), and specific examples of the onium salts ([OS-1] to [OS-7]) represented by the general formula (C), are not limited thereto. .

  The polymerization initiator 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.

Other preferable polymerization initiators include specific aromatic sulfonium salts described in Japanese Patent Application Nos. 2000-266797, 2002-148790, 2001-343742, and 2002-6482. It is done. The typical compound is illustrated below.
Below, the typical compound of the other preferable polymerization initiator which can be applied to this invention is illustrated.

  Moreover, the oxime ester compound which can be used suitably as a polymerization initiator in this invention is demonstrated below. Preferred oxime ester compounds include compounds represented by the following general formula (D).

  In general formula (D), X represents a carbonyl group, a sulfone group, or a sulfoxide group, and Y represents a cyclic or chain alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, or an aryl group having 6 to 18 carbon atoms. An aryl group is an aromatic hydrocarbon compound such as a benzene ring, naphthalene ring, anthracene ring, phenanthrene group, pyrene group, triphenylene group, and a heterocyclic ring is a nitrogen atom, sulfur atom, oxygen atom For example, a pyrrole group, a furan group, a thiophene group, a selenophenone group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, a thiazole group, an indole group, Benzofuran group, benzimidazole group, benzoxazole group, benzothiazole group, pyridine group Pyrimidine group, a pyrazine group, a triazine group, a quinoline group, a carbazole group, an acridine group, a phenoxazine, and a compound such as phenothiazine. These substituents represented by Y are halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, aldehyde group, alkyl group, thiol group, aryl group or alkenyl group, alkynyl group, ether group, ester group, urea Group, amino group, amide group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl group, imino group, halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, carbonyl group, urethane It can be substituted by a compound containing a group, an alkyl group, a thiol group, an aryl group, a phosphoroso group, a phospho group, or a carbonyl ether group.

  Z in the general formula (D) is synonymous with Y or is a nitrile group, a halogen atom, a hydrogen atom, or an amino group, and these Z compounds are halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, aldehyde groups. , Alkyl group, thiol group, aryl group or alkenyl group, alkynyl group, ether group, ester group, urea group, amino group, amide group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl Substitutable with compounds containing groups, imino groups, halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, carbonyl groups, urethane groups, alkyl groups, thiol groups, aryl groups, phosphoroso groups, phospho groups, carbonyl ether groups It is.

  W in the general formula (D) represents a divalent organic group, and represents a methylene group, a carbonyl group, a sulfoxide group, a sulfone group, or an imino group. The methylene group and the imino group are an alkyl group, an aryl group, an ester group, and a nitrile. It can be substituted by a compound containing a group, a carbonyl ether group, a sulfo group, a sulfo ether group, an ether group or the like. n represents an integer of 0 or 1.

V in the general formula (D) is a cyclic or chain alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an aryl group having 6 to 18 carbon atoms, an alkoxy group, or an aryloxy group. Aromatic hydrocarbon compounds such as benzene ring, naphthalene ring, anthracene ring, phenanthrene group, pyrene group, triphenylene group, pyrrole group, furan group, thiophene group, selenophene group, pyrazole group, imidazole group, triazole group, tetrazole group, oxazole Group, thiazole group, indole group, benzofuran group, benzimidazole group, benzoxazole group, benzothiazole group, pyridine group, pyrimidine group, pyrazine group, triazine group, quinoline group, carbazole group, acridine group, phenoxazine, phenothiazine, etc. Including heteroatoms Aromatics. These V compounds are halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, aldehyde groups, alkyl groups, thiol groups, aryl groups or alkenyl groups, alkynyl groups, ether groups, ester groups, urea groups, amino groups, amides. Group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl group, imino group, halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, carbonyl group, urethane group, alkyl group, thiol It can be substituted by a compound containing a group, an aryl group, a phosphoroso group, a phospho group or a carbonyl ether group.
V and Z may be bonded to each other to form a ring.

As the oxime ester compound represented by the general formula (D), from the viewpoint of sensitivity, X is carbonyl, Y is an aryl group or benzoyl group, Z group is an alkyl group or aryl group, W is a carbonyl group, V Is preferably an aryl group. More preferably, the aryl group of V has a thioether substituent.
Note that the structure of the N—O bond in the general formula (D) may be E-form or Z-form.

  Other oxime ester compounds that can be suitably used in the present invention include Progress in Organic Coatings, 13 (1985) 123-150; C. S Perkin II (1979) 1653-1660; Journal of Photopolymer Science and Technology (1995) 205-232; C. S Perkin II (1979) 156-162; JP-A 2000-66385; JP-A 2000-80068.

  Although the specific example of the oxime ester compound which can be used suitably for this invention is shown below, it is not limited to this.

  These polymerization initiators are preferably from 0.1 to 50% by mass, more preferably from 0.1 to 50% by mass, based on the total solid content constituting the image recording layer, from the viewpoints of sensitivity and contamination of the non-image area that occurs during printing. It can be added in a proportion of 5 to 30% by mass, particularly preferably 1 to 20% by mass. These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

<Sensitizing dye>
In the lithographic printing plate precursor according to the invention, the image recording layer may contain a sensitizing dye. The sensitizing dye preferably has an absorption peak at 350 to 850 nm. Examples of such sensitizing dyes include spectral sensitizing dyes and the following dyes or pigments that absorb light from a light source and interact with a photopolymerization initiator.
Preferred spectral sensitizing dyes or dyes include polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thianes). Carbocyanine, oxacarbocyanine), merocyanines (eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), phthalocyanines ( For example, phthalocyanine, metal phthalocyanine), porphyrins (for example, tetraphenylporphyrin, central metal-substituted porphyrin), chlorophylls (for example, chlorophyll, chlorophyllin, central gold) Substituted chlorophyll), metal complexes, anthraquinones (e.g., anthraquinone), squaryliums (e.g., squarylium), and the like.

  Examples of more preferable spectral sensitizing dyes or dyes include styryl dyes described in JP-B-37-13034, cationic dyes described in JP-A-62-143044, and quinoxalinium described in JP-B-59-24147. Salts, new methylene blue compounds described in JP-A No. 64-33104, anthraquinones described in JP-A No. 64-56767, benzoxanthene dyes described in JP-A No. 2-1714, JP-A No. 2-226148 and special Acridines described in each publication of Japanese Utility Model Laid-Open No. 2-226149, pyrylium salts described in Japanese Patent Publication No. 40-28499, cyanines described in Japanese Patent Publication No. 46-42363, benzofuran dyes described in Japanese Patent Publication No. 2-63053, Conjugated ketone dyes described in JP-A-2-85858 and JP-A-2-216154 HirakiAkira 57-10605 described in JP-dye. Azocinnamylidene derivatives described in JP-B-2-30321, cyanine dyes described in JP-A-1-287105, JP-A-62-31844, JP-A-62-31848, JP-A-62-143043 Xanthene dyes described in Japanese Patent Publication Nos. JP-A Nos. 59-28325, merocyanine dyes described in JP-B No. 61-9621, and dyes described in JP-A No. 2-179433. A merocyanine dye described in JP-A-2-244050, a merocyanine dye described in JP-B-59-28326, a merocyanine dye described in JP-A-59-89803, a merocyanine dye described in JP-A-8-129257, and Examples thereof include benzopyran dyes described in JP-A-8-334897.

  The content of the sensitizing dye is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 1 to 20% by mass with respect to the total solid content constituting the image recording layer. It is.

<Polymerizable compound>
The image recording layer of the present invention preferably contains a polymerizable compound in order to perform an efficient curing reaction. The polymerizable compound that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is a compound having at least one terminal ethylenically unsaturated bond, preferably two or more. To be elected. 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, i.e. 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 a monofunctional or polyfunctional compound. 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 Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. 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, isocyanuric acid There are EO-modified triacrylate and the like.

  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-51-47334 and JP-A-57-196231, JP-A-59-5240, JP-A-59-5241, and JP-A-2-226149. Those having the aromatic skeleton described above and those having 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 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 (II) to a polyisocyanate compound having two or more isocyanate groups. Compounds and the like.

_{CH 2 = C (R 4)} COOCH 2 CH (R 5) OH (II)
(However, R ₄ and R ₅ 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 acrylic acid or methacrylic acid described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-B-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 performance design of the final planographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. A method of adjusting both sensitivity and strength by using a compound) is also effective.
Further, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components (for example, binder polymer, initiator, colorant, etc.) in the image recording layer. In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the substrate and the protective layer described later.

  The polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass with respect to the nonvolatile component in the image recording layer. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<Binder polymer>
The image recording layer of the present invention may contain a binder polymer in addition to the graft polymer. As the binder polymer that can be used in the present invention, a conventionally known binder polymer can be used without limitation, and a linear organic polymer having film properties is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

  The binder polymer preferably has crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.

Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid where the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).

Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  In the case of a binder polymer having crosslinkability, for example, free radicals (polymerization initiation radicals or growth radicals in the polymerization process of a polymerizable compound) are added to the crosslinkable functional group, and a polymerization chain of a polymerizable compound is formed directly between polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded to each other so that crosslinking between the polymer molecules occurs. Forms and cures.

  The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol. Within this range, good sensitivity and good storage stability can be obtained.

From the viewpoint of improving the on-press developability, the binder polymer preferably has high solubility or dispersibility in ink and / or fountain solution.
In order to improve the solubility or dispersibility in ink, the binder polymer is preferably lipophilic, and in order to improve the solubility or dispersibility in dampening water, the binder polymer is hydrophilic. Is preferred. For this reason, in the present invention, it is also effective to use a lipophilic binder polymer and a hydrophilic binder polymer in combination.

  Examples of hydrophilic binder polymers include hydroxy groups, carboxyl groups, carboxylate groups, hydroxyethyl groups, polyoxyethyl groups, hydroxypropyl groups, polyoxypropyl groups, amino groups, aminoethyl groups, aminopropyl groups, and ammonium. Preferred are those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, homopolymers of hydroxybutyl methacrylate Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate Polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a degree of hydrolysis of 60% by mass or more, preferably 80% by mass or more , Methacrylamide homopolymers and polymers, N-methylolacrylamide homopolymers and copolymers, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. Is mentioned.

  The binder polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  The binder polymer may be either a random polymer or a block polymer, but is preferably a random polymer. Moreover, a binder polymer may be used independently or may be used in mixture of 2 or more types.

The binder polymer can be synthesized by a conventionally known method. Examples of the solvent used in the synthesis include tetrahydrofuran, ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy. Examples include 2-propanol, 1-methoxy-2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, and water. These may be used alone or in combination of two or more.
As the radical polymerization initiator used when synthesizing the binder polymer, known compounds such as an azo initiator and a peroxide initiator can be used.

The content of the binder polymer is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, and still more preferably 10 to 70% by mass with respect to the total solid content of the image recording layer. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 0.5 / 1-9/1 by mass ratio.

<Surfactant>
In the present invention, it is preferable to use a surfactant in the image recording layer in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

  The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.

  The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imidazolines.

  Of the above surfactants, the term “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Moreover, the fluorine-type surfactant described in each gazette of Unexamined-Japanese-Patent No. 62-170950, 62-226143, and 60-168144 is also mentioned suitably.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass, and more preferably 0.01 to 7% by mass, based on the total solid content of the image recording layer.

<Colorant>
In the present invention, various compounds other than these may be added as necessary. For example, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.

  These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The amount added is preferably 0.01 to 10% by mass relative to the total solid content of the image recording material.

<Bakeout agent>
In the image recording layer of the present invention, a compound that changes color by an acid or a radical can be added to produce a printout image. As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

  Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).

  In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoyl leucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by an acid or a radical is 0.01 to 10% by mass with respect to the solid content of the image recording layer.

<Polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the (C) radical polymerizable compound during production or storage of the image recording layer, it is preferable to add a small amount of a thermal polymerization inhibitor to the image recording layer of the present invention.
Examples of the thermal polymerization inhibitor 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-t-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to the image recording layer of the present invention, and the surface of the image recording layer is dried during the coating process. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

<Plasticizer>
The image recording layer of the present invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

<Inorganic fine particles>
The image recording layer of the present invention may contain inorganic fine particles for the purpose of improving the strength of the cured film in the image area and improving the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 to 3 μm. Within the above range, it is possible to form a non-image portion having excellent hydrophilicity, which is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total solid content of the image recording layer.

<Low molecular hydrophilic compound>
The image recording layer of the present invention may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of hydrophilic low molecular weight compounds include water-soluble organic compounds such as glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

(Formation of image recording layer)
In the present invention, several modes can be used as a method for incorporating the above-mentioned image recording layer constituents into the image recording layer. One is, for example, an embodiment in which the constituent components are dissolved and applied in an appropriate solvent as described in JP-A-2002-287334, and the other is, for example, JP-A-2001-277740, As described in Japanese Patent Application Laid-Open No. 2001-277742, it is an embodiment (microcapsule type image recording layer) in which the constituent components of the image recording layer are encapsulated in microcapsules and contained in the image recording layer. Further, in the microcapsule type image recording layer, the constituent component can be contained outside the microcapsule. In the microcapsule type image recording layer, it is preferable that the hydrophobic constituent component is encapsulated in the microcapsule and the hydrophilic constituent component is contained outside the microcapsule. In order to obtain better on-press developability, the image recording layer is preferably a microcapsule type image recording layer.

  As a method of microencapsulating the above-mentioned image recording layer constituent components, known methods can be applied. For example, as a method for producing microcapsules, a method using coacervation found in U.S. Pat. Nos. 2,800,547 and 2,800,498, U.S. Pat. No. 3,287,154, JP-B-38-19574, 42-446 by the interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304 by polymer precipitation method, US Pat. No. 3,796,669, isocyanate polyol A method using a wall material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, and a urea-formaldehyde system found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802. Or urea formaldehyde-resorcino A method using a wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method using monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Further, a compound having a crosslinkable functional group such as an ethylenically unsaturated bond capable of introducing the binder polymer may be introduced into the microcapsule wall.

  The average particle size of the microcapsules is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

The image recording layer of the present invention is applied by preparing a coating solution by dispersing or dissolving the necessary components described above in a solvent. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, water and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
The image recording layer of the present invention can be formed by preparing a plurality of coating liquids in which the same or different components are dispersed or dissolved in the same or different solvents, and repeatedly applying and drying a plurality of times.

Further, the coating amount (solid content) of the image recording layer on the support obtained after coating and drying varies depending on the use, but generally 0.3 to 3.0 g / m ² is preferable. Within this range, good sensitivity and good film properties of the image recording layer can be obtained.
Various methods can be used as the coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm, and even more preferably from 0.2 to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to the roughening treatment of the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (electrochemical surface roughening treatment that dissolves the surface), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions of anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, an electrolyte concentration of 1 to 80% by mass solution, a liquid temperature of 5 to 70 ° C., a current density of 5 to 60 A / d m ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, it contains a micropore enlargement treatment, a micropore sealing treatment, and a hydrophilic compound described in Japanese Patent Application Laid-Open Nos. 2001-253181 and 2001-322365. A surface hydrophilization treatment immersed in an aqueous solution can be selected as appropriate. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

Sealing treatment includes vapor sealing, single treatment with zirconic fluoride, treatment with aqueous solution containing inorganic fluorine compounds such as treatment with sodium fluoride, vapor sealing with addition of lithium chloride, sealing with hot water. Hole processing is also possible.
Of these, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable.

  The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are such alkali metal silicate methods. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.

When using a support with insufficient surface hydrophilicity such as a polyester film as the support of the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. As the hydrophilic layer, at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A-2001-199175 A hydrophilic layer obtained by coating a coating solution containing a colloid of oxide or hydroxide, or an organic hydrophilic polymer obtained by crosslinking or pseudo-crosslinking an organic hydrophilic polymer described in JP-A No. 2002-79772 A hydrophilic layer having a hydrophilic matrix, a hydrophilic layer having an inorganic hydrophilic matrix obtained by sol-gel conversion comprising hydrolysis, condensation reaction of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer made of an inorganic thin film having a surface is preferred. Arbitrariness. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or a hydroxide colloid is preferable.

  Moreover, when using a polyester film etc. as a support body of this invention, it is preferable to provide an antistatic layer in the hydrophilic layer side of a support body, the opposite side, or both sides. In the case where the antistatic layer is provided between the support and the hydrophilic layer, it also contributes to improving the adhesion with the hydrophilic layer. As the antistatic layer, a polymer layer in which metal oxide fine particles or a matting agent are dispersed as described in JP-A-2002-79772 can be used.

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion with the image recording layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Among them, it is inexpensive to use a silicon alkoxy compound such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4. It is preferable in terms of easy availability.

[Undercoat layer]
In the lithographic printing plate precursor according to the invention, particularly in the case of an on-press development type lithographic printing plate precursor, an undercoat layer can be provided between the image recording layer and the support, if necessary. Since the undercoat layer easily peels off the image recording layer from the support in the unexposed area, the on-press developability is improved. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, so that heat generated by exposure does not diffuse to the support and can be used efficiently, so that high sensitivity can be achieved. There are advantages.
As the undercoat layer compound (undercoat compound), specifically, a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in JP-A-10-282679, Preferable examples include phosphorus compounds having an ethylenic double bond reactive group described in JP-A-2-304441.
Preferred undercoat compounds include (a1) a copolymer having a repeating unit containing at least one ethylenically unsaturated bond and (a2) a repeating unit containing at least one functional group that interacts with the support surface. Can be mentioned. Furthermore, (a3) a copolymer containing a repeating unit containing at least one hydrophilic group is more preferred.

  Examples of the functional group that interacts with the surface of the hydrophilic support (hereinafter sometimes abbreviated as “adsorptive group”) include, for example, a metal present on the support that has been subjected to anodization treatment or hydrophilic treatment, Examples thereof include groups capable of interacting with metal oxides, hydroxyl groups and the like such as covalent bonds, ionic bonds, hydrogen bonds, polar interactions, and van der Waals interactions.

The presence / absence of interaction with the surface of the hydrophilic support can be determined by, for example, the following method of measuring the amount of adsorption.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, the support coated with the test compound is sufficiently washed with a readily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorbed amount of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. Even if the washing treatment as described above is performed, a compound remaining in an amount of 1 mg / m ² or more is regarded as a compound capable of adsorbing the support, that is, a compound interacting with the support.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) or a functional group (for example, hydroxyl group) existing on the surface of the hydrophilic support and a chemical bond (for example, ionic bond, hydrogen bond). , Coordination bond, bond by intermolecular force). The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of acid groups are phenolic hydroxyl groups, carboxyl groups, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ — and —COCH _2. Contains COCH ₃ . Among them -OPO ₃ H ₂ and -PO ₃ H ₂ are particularly preferred. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. An ammonium group, a phosphonium group and a sulfonium group are preferred, an ammonium group and a phosphonium group are more preferred, and an ammonium group is most preferred.

  Particularly preferred examples of the monomer having an adsorptive group include compounds represented by the following formula (III) or (IV).

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms, and X represents an oxygen atom (—O—) or imino (— NH-), L represents a divalent linking group, Z represents a functional group adsorbed on the surface of the hydrophilic support, and Y represents a carbon atom or a nitrogen atom.

In the formula (III), R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. R ¹ , R ² and R ³ are preferably each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferred is a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
In the formula (III), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom. In the formula (III), L is a divalent linking group. L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group) or divalent Or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, where R is an aliphatic group, an aromatic group. Or a combination with a heterocyclic group) or carbonyl (—CO—).
The aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. The aliphatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aromatic group, and a heterocyclic group.
The number of carbon atoms in the aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. The aromatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aliphatic group, an aromatic group, and a heterocyclic group.
The heterocyclic group preferably has a 5-membered or 6-membered ring as the heterocycle. The heterocycle may be condensed with another heterocycle, aliphatic ring or aromatic ring. The heterocyclic group may have a substituent. Examples of substituents include halogen atoms, hydroxyl groups, oxo groups (═O), thioxo groups (═S), imino groups (═NH), substituted imino groups (═N—R, R is an aliphatic group, aromatic Group or heterocyclic group), aliphatic group, aromatic group and heterocyclic group.
L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).
In the formula (III), Z is a functional group that adsorbs to the surface of the hydrophilic support. Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is connected to Y to form a quaternary pyridinium group, Z is not essential because it exhibits adsorptivity itself.

  Examples of typical monomers represented by formula (III) or (IV) are shown below.

  The copolymer for the undercoat layer of the present invention preferably contains at least one ethylenically unsaturated bond. The adhesion with the image area is improved by the ethylenically unsaturated bond. In order to make the copolymer for the undercoat layer have an ethylenically unsaturated bond, a crosslinkable functional group having an ethylenically unsaturated bond is introduced into the side chain of the polymer, or polar substitution of the copolymer is performed. A salt structure can be formed by introducing a group, a substituent having a counter charge and a compound having an ethylenically unsaturated bond.

  Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid where the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the crosslinkable group having an ethylenically unsaturated bond (the above R) include — (CH ₂ ) _n CR ₁ ═C
_{R 2 R 3, - (CH} 2 O) n CH 2 CR 1 = CR 2 R 3, - (CH 2 CH 2 O) n CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO _{-O-CH 2 CR 1 = CR} 2 R 3, - (CH 2) n -O-CO-CR 1 = CR 2 R 3, and _{- (CH 2 CH 2 O)} 2 -X ( in the formula, R ₁ -R ₃ represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, an aryl group, an alkoxy group or an aryloxy group, and R ₁ and R ₂ or R ₃ are bonded to each other to form a ring. N represents an integer of 1 to 10. X represents a dicyclopentadienyl residue.
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 NHCOO-CH 2 CH = CH 2, and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.
As the monomer having a crosslinkable group for the copolymer for the undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is preferable.

  The content of the crosslinkable group in the copolymer for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the copolymer, More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

  Examples of the hydrophilic group of the repeating unit containing at least one hydrophilic group of the undercoating copolymer include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, a hydroxypropyl group, a polypropylene group, and the like. Preferable examples include oxypropyl group, amino group, aminoethyl group, aminopropyl group, ammonium group, amide group, carboxymethyl group, sulfonic acid group, and phosphoric acid group. Among them, a monomer having a sulfonic acid group exhibiting high hydrophilicity is preferable. Specific examples of the monomer having a sulfonic acid group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, allylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t -Sodium sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, sodium salt of (3-acryloyloxypropyl) butyl sulfonic acid, and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and synthetic handling.

The copolymer for the undercoat layer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 2000 More preferably, it is 250,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The copolymer for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer and the like, but is preferably a random polymer.

  In the present invention, the copolymer may be contained in the image recording layer, or may be contained in a layer adjacent to the image recording layer such as an undercoat layer (intermediate layer) provided between the support and the image recording layer. However, it is particularly preferable to use it in the undercoat layer because the effect of the present invention is sufficiently exhibited. A copolymer may be used independently or may be used in mixture of 2 or more types.

The undercoat layer coating solution is obtained by dissolving the above undercoat copolymer in an organic solvent (eg, methanol, ethanol, acetone, methyl ethyl ketone, etc.) and / or water. The undercoat layer coating solution may contain an infrared absorber.
Various known methods can be used as a method of applying the undercoat layer coating solution to the support. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 1 to 30 mg / m ^2.

[Protective layer]
The lithographic printing plate precursor of the present invention is protected on the image recording layer as necessary to impart oxygen barrier properties, prevent scratches in the image recording layer, and prevent ablation that occurs during high-illuminance laser exposure. A layer (overcoat layer) can be provided.

  Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image forming reaction in the image recording layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the image recording layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the properties desired for the protective layer are to reduce the permeability of low-molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the image recording layer is excellent. And it can be easily removed in an on-press development process after exposure. The overcoat layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

As a material used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, starch Examples thereof include water-soluble polymers such as derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane. These may be used in combination of two or more as required.
A relatively useful material among the above materials includes water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol that can be used in the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of an unsubstituted vinyl alcohol unit having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester-modified site of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as an ester modified site and an epoxy modified site of the anion modified site and alcohols, etc. at the polymer chain end are also preferably used.

  Suitable examples of these modified polyvinyl alcohols include compounds having a hydrolysis degree of 71 to 100% and a polymerization degree in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8 and the like. Further, as modified polyvinyl alcohol, KL-318, KL-118, KM-618, KM-118, SK-5102 having anion-modified sites, C-318, C-118, CM-318 having cation-modified sites, terminal M-205 having a thiol modification site, M-115, MP-103 having a terminal sulfide modification site, MP-203, MP-102, MP-202, HL-12E having an ester modification site with a higher fatty acid at the end, HL-1203, R-1130, R-2105, R-2130, etc. having other reactive silane modification sites.

The protective layer preferably contains a layered compound. The layered compound is a particle having a thin plate shape, for example, natural mica represented by the following general formula, mica group such as synthetic mica, talc represented by the formula 3MgO · 4SiO · H ₂ O, teniolite, Examples thereof include montmorillonite, saponite, hectorite, and zirconium phosphate.
A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂

  [However, A is any of Li, K, Na, Ca, Mg, organic cation, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, V, and D is Si or Al].

Examples of the natural mica include muscovite, zoda mica, phlogopite, biotite and sericite. Further, as the synthetic mica, non-swelling mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( Si ₄ O ₁₀ ) F ₂ , Na or Li Teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , Montmorillonite Na or Li Hectorite (Na, Li) _1/8 Mg _2/5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic smectite is also useful.
Of the above layered compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, sabonite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than It is significantly larger than clay minerals. As a result, the lattice layer suffers from a shortage of positive charge, and in order to compensate for this, the layers such as Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are used. Adsorbs organic cation cations. These layered compounds swell with water. If shear is applied in this state, it will be easily cleaved to form a stable sol in water. Bentonite and swelling synthetic mica have this tendency.

  As the shape of the layered compound, from the viewpoint of diffusion control, the thinner the better, the better the planar size as long as the smoothness of the coated surface and the transmittance of actinic rays are not impaired. 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 projection view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

The average particle diameter of the layered compound is 1 to 20 μm, preferably 1 to 10 μm, and particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the suppression of permeation of oxygen and moisture is insufficient, and the effect cannot be exhibited sufficiently. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. 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. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When particles of inorganic layered compounds having a large aspect ratio are contained in the protective layer as described above, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Even when stored for a long time under high humidity conditions, the storage stability of the lithographic printing plate precursor is not deteriorated due to changes in humidity, and the storage stability is excellent.

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for an overcoat layer. Even when a plurality of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to give flexibility. Also, sodium alkyl sulfate, alkyl sulfonic acid Anionic surfactants such as sodium; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ether can be added. The addition amount of these activators can be added in an amount of 0.1 to 100% by mass with respect to the (co) polymer.

  In order to improve the adhesion to the image area, for example, JP-A-49-70702 and British Patent Application No. 1303578 include an acrylic polymer in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesion can be obtained by mixing 20 to 60% by mass of a water-based emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and the like, and laminating the mixture on an image recording layer. Any of these known techniques can be used in the present invention.

  Furthermore, other functions can be imparted to the protective layer. For example, it is excellent in the transparency of infrared rays used for exposure and can efficiently absorb light of other wavelengths. Addition of a colorant (for example, a water-soluble dye) can improve safelight suitability without causing a decrease in sensitivity.

  Next, an example of a general dispersion method of the layered compound used for the protective layer will be described. First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar 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, a disperser that provides high-intensity ultrasonic energy, and the like. 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 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled, and the storage stability is very good. When preparing a protective layer coating solution using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

This protective layer coating solution includes known anionic surfactants, nonionic surfactants, cationic surfactants, fluorosurfactants for improving coatability and water-soluble plasticizers for improving the physical properties of the film. Additives can be added. 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 with the image recording layer and the temporal stability of the coating solution may be added to the coating solution.

The overcoat layer coating solution thus prepared is applied onto the image recording layer provided on the support and dried to form the overcoat layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for coating the overcoat layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. it can. Specific examples of the overcoat layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.
The coating amount of the overcoat layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / m ^2, more preferably in the range of 0.02 to 3 g / m ^2, most preferably 0 The range is 0.02 to 1 g / m ² .

[Lithographic printing method]
As a light source for exposing the lithographic printing plate precursor according to the invention, a known light source can be used without limitation. The wavelength of a desirable light source is 300 nm to 1200 nm. Specifically, it is preferable to use various lasers as the light source, and among these, a semiconductor laser that emits infrared light with a wavelength of 760 nm to 1200 nm is preferably used.
The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.
In addition, as other exposure beams for the lithographic printing plate precursor of the present invention, ultra-high pressure, high pressure, medium pressure, low pressure mercury lamps, chemical lamps, carbon arc lamps, xenon lamps, metal halide lamps, various visible and ultraviolet laser lamps Fluorescent lamps, tungsten lamps, sunlight, etc. can also be used.

In the lithographic printing method of the present invention, as described above, after exposing the lithographic printing plate precursor of the present invention imagewise with a laser, the oil-based ink and the aqueous component are supplied without any development processing steps. Print.
Specifically, after a lithographic printing plate precursor is exposed with a laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on a printing machine, a laser is used on the printing machine. And a method of printing without passing through a development processing step.

  After the lithographic printing plate precursor is imagewise exposed with a laser, printing is performed by supplying an aqueous component and an oil-based ink without passing through a development processing step such as a wet development processing step. The image recording layer cured by the above process forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in that area.

As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, the water-based component or oil-based ink may be first supplied to the plate surface, but the oil-based ink is first used in order to prevent the water-based component from being contaminated by the image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and the oil-based ink, a normal fountain solution for lithographic printing and printing ink are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
The following Examples 1 to 5 and 11 to 13 shall be read as Reference Examples 1 to 5 and 11 to 13, respectively.

<Synthesis of graft polymer (A-1) having an ethylenically unsaturated bond in a hydrophobic main chain and having a hydrophilic segment as a graft chain>
(Synthesis of hydrophilic macromer)
30 g of acrylamide and 3.8 g of 3-mercaptopropionic acid are dissolved in 70 g of ethanol, and the temperature is raised to 60 ° C. in a nitrogen atmosphere, and 300 mg of a thermal polymerizable initiator 2,2′-azobisisobutyronitrile (AIBN) is added. For 6 hours. After the reaction, the white precipitate was filtered and sufficiently washed to obtain 30.8 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.78 meq / g, mass average molecular weight 1.3 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was put into acetone, the polymer was precipitated, and washed well to obtain 23.4 g of terminal methacrylate acrylamide macromonomer. (Mass average molecular weight: 1.4 × 10 ³ ). ¹ H-NMR (D ₂ O) 6.12, 5.70 ppm The presence of a methacryloyl group olefin peak and a decrease in the carboxylic acid value (0.023 meq / g) confirm that a polymerizable group can be introduced at the terminal. did. The glass transition temperature of the hydrophilic macromer was measured by a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc. and found to be 160 ° C.

(Synthesis of radical polymerizable compound M-1)
In a 1000 ml three-necked flask, a solution of 133 g of 2-hydroxyethyl methacrylate in 520 ml of THF was prepared and cooled to 0 ° C. While stirring, 130 g of 3-chloropropionic acid chloride was dropped over 1 hour using a dropping funnel, and then the temperature was gradually raised to room temperature. After stirring at room temperature for 12 hours, the reaction solution was poured into 1 L of ice water. After stirring for 1 hour, extraction was performed with 2 L of ethyl acetate in three portions, and the resulting organic layer was washed successively with water, saturated aqueous sodium hydrogen carbonate solution and saturated brine, and then dried over magnesium sulfate. After filtration, the solvent was distilled off under reduced pressure using a rotary evaporator. The obtained residue was purified by silica gel column chromatography (elution solvent; hexane / ethyl acetate) to obtain 180 g of Compound (M-1). The structure of the compound (M-1) was confirmed from NMR, mass spectrometry spectrum and IR.

(Synthesis of graft polymer (A-1) having an ethylenically unsaturated bond in a hydrophobic main chain and a hydrophilic segment as a graft chain)
15 g of N, N-dimethylacetamide amide is placed in a flask, heated to 60 ° C. in a nitrogen atmosphere, 10 g of the above macromonomer, 5 g of methyl methacrylate, 4.6 g of compound (M-1), thermal polymerizable initiator 2 , 2′-Azobisisobutyronitrile (150 mg) dissolved in N, N-dimethylacetamide amide (15 g) was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain a graft polymer having hydrophilic segments as graft chains.
26 g of the obtained graft polymer and 0.1 g of p-methoxyphenol were put into the flask, dissolved in 60 g of N, N-dimethylacetamide and 60 g of acetone, and cooled in an ice bath containing ice water. After the temperature of the mixture became 5 ° C. or lower, 20.3 g of 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) was added dropwise over 1 hour. After completion of dropping, the ice bath was removed and the mixture was further stirred for 8 hours. The product was precipitated and washed well to obtain graft polymer (A-1). When ¹ H-NMR of the obtained graft polymer was measured, it was confirmed that 100% of the side chain groups derived from the compound (M-1) were converted to ethylene methacrylate groups. The mass average molecular weight is shown in Table 1.

<Synthesis of graft polymer (A-2 to 5) having hydrophilic segment as graft chain>
Graft polymers (A-2) to (A-5) were synthesized in the same manner as the synthesis of graft polymer (A-1) except that the hydrophobic monomer (methyl methacrylate) in the above synthesis example was changed as shown in Table 1. Obtained. The mass average molecular weight is shown in Table 1.

<Synthesis of graft polymer (B-1) having a hydrophobic segment having an ethylenically unsaturated bond as a graft chain>
(Synthesis of hydrophobic macromers)
After dissolving 44 g of styrene, 9.2 g of compound (M-1), and 3.8 g of 3-mercaptopropionic acid in 88 g of methyl ethyl ketone, the temperature was raised to 60 ° C. in a nitrogen atmosphere, and the thermal polymerizable initiator 2,2′-azobis 300 mg of isobutyronitrile (AIBN) was added and reacted for 6 hours. After the reaction, the white precipitate was filtered and sufficiently washed to obtain 38.5 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.75 meq / g, mass average molecular weight 1.25 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was put into acetone, the polymer was precipitated, and washed well to obtain 23.4 g of terminal methacrylate acrylamide macromonomer. (Mass average molecular weight: 1.33 × 10 ³ ). ¹ H-NMR (D ₂ O) 6.12, 5.70 ppm The presence of a methacryloyl group olefin peak and a decrease in the carboxylic acid value (0.019 meq / g) confirmed that a polymerizable group could be introduced at the terminal. did. The glass transition temperature of the hydrophilic macromer was measured with a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc. and found to be 90 ° C.

(Synthesis of graft polymer having a hydrophobic segment having an ethylenically unsaturated bond as a graft chain)
15 g of N, N-dimethylacetamide amide is placed in a flask, heated to 60 ° C. in a nitrogen atmosphere, 10 g of the macromonomer, 5 g of methacrylamide, 150 mg of 2,2′-azobisisobutyronitrile, a thermal polymerizable initiator. Was added dropwise over 2 hours in a solution of 15 g of N, N-dimethylacetamide amide. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain a graft polymer having a hydrophobic segment as a graft chain.
26 g of the obtained graft polymer and 0.1 g of p-methoxyphenol were placed in a flask, dissolved in 60 g of N, N-dimethylacetamide and 60 g of acetone, and cooled in an ice bath containing ice water. After the temperature of the mixture became 5 ° C. or lower, 20.3 g of 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) was added dropwise over 1 hour. After completion of dropping, the ice bath was removed and the mixture was further stirred for 8 hours. The product was precipitated and washed well to obtain 14.5 g of graft polymer (B-1) (mass average molecular weight 1.0 × 10 ⁵ ). When ¹ H-NMR of the obtained graft polymer was measured, it was confirmed that 100% of the side chain groups derived from the compound (M-1) were converted to ethylene methacrylate groups. The mass average molecular weight is shown in Table 1.

<Synthesis of Graft Polymer (B-2 to 5) with Hydrophobic Segment Having Ethylenically Unsaturated Bond as Graft Chain>
Graft polymers (B-2) to (B-5) were prepared in the same manner as the synthesis of graft polymer (B-1) except that the hydrophilic monomer (methacrylamide) in the above synthesis example was changed as shown in Table 2. Obtained. The mass average molecular weight is shown in Table 2.

<Synthesis of Comparative Graft Polymer (C-1)>
Take 53 g of 1-methoxy-2-propanol in a flask, raise the temperature to 60 ° C. in a nitrogen atmosphere, then 22 g of methyl methacrylate, 30 g of polyoxyethylene monomethacrylate (Nippon Yushi Co., Ltd., Bremer PME1000), start of thermal polymerization A solution prepared by dissolving 250 mg of the agent 2,2′-azobisisobutyronitrile in 53 g of 1-methoxy-2-propanol was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 45 g of a comparative graft polymer (C-1) (mass average molecular weight 1.3 × 10 ⁵ ).
<Synthesis of Comparative Graft Polymer (C-2)>
Taking 53 g of 1-methoxy-2-propanol in a flask and raising the temperature to 60 ° C. under a nitrogen atmosphere, 22 g of methacrylamide, 30 g of polymethyl methacrylate monomer (AA-1 manufactured by Toa Gosei Co., Ltd.), thermal polymerization start A solution prepared by dissolving 250 mg of the agent 2,2′-azobisisobutyronitrile in 53 g of 1-methoxy-2-propanol was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 45 g of a comparative graft polymer (C-1) (mass average molecular weight 1.4 × 10 ⁵ ).

<Production of support>
In order to remove rolling oil on the surface of an aluminum plate (material JIS A1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then the hair diameter was 0.3 mm. The surface of the aluminum plate was grained using 3 bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. This plate was etched by being immersed in a 25% aqueous sodium hydroxide solution at 45 ° C. for 9 seconds, washed with water, further immersed in 20% nitric acid at 60 ° C. for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power supply waveform is an electrochemical roughening process using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec and a duty ratio of 1: 1 until the current value reaches a peak from zero, using a carbon electrode as a counter electrode. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode.
Then, water washing by spraying was performed.

Next, the above-mentioned nitric acid was added under the condition of 0.5 mass% hydrochloric acid aqueous solution (containing 0.5 mass% of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. and an electric quantity of 50 C / dm ² when the aluminum plate is an anode. An electrochemical surface roughening treatment was performed in the same manner as in electrolysis, and then water washing by spraying was performed. After the plate form a direct current anodized film of 2.5 g / m ² at a current density of 15A / dm ² 15% sulfuric acid (containing 0.5 mass% aluminum ion) as the electrolytic solution, washed with water, dried, further Then, it was treated with a 2.5 mass% aqueous solution of sodium silicate at 30 ° C for 10 seconds. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

An undercoat layer containing a water-soluble polymer is provided by applying the following undercoat liquid (1) to the above support so that the dry coating amount is 10 mg / m ^2, and a support with an undercoat layer used in the following experiments is provided. Produced.

Undercoat liquid (1)
・ Undercoat compound (1) 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

[Examples 1 to 10, Comparative Examples 1 and 2]
<Preparation of lithographic printing plate precursor>
An image recording layer coating solution (1) having the following composition was bar-coated on the above support, followed by oven drying at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. A lithographic printing plate precursor was obtained. Subsequently, a protective layer coating solution (1) having the following composition is bar-coated on the image recording layer and oven-dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. The lithographic printing plate precursors 1 to 10 and the comparative lithographic printing plate precursors 1 ′ and 2 ′ were obtained.

Image recording layer coating solution (1)
・ The following infrared absorber (1) 0.05 g
・ The following polymerization initiator (1) 0.2 g
・ 0.5 g of graft polymer listed in Table 3
・ Polymerizable compound 1.0g
Aronix M-215 (manufactured by Toa Gosei Co., Ltd.)
・ Victoria Pure Blue Naphthalenesulfonate 0.02g
・ 0.1 g of the following fluorosurfactant (1)
・ Methyl ethyl ketone 18.0g

Protective layer coating solution (1)
-1.5g of the following inorganic particle dispersion (1)
・ Polyvinyl alcohol PVA105 0.06g
(Kuraray Co., Ltd., fighting degree 98.5 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone K30 0.01g
(Made by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
-Vinylpyrrolidone and vinyl acetate copolymer LUVITEC 0.01g
VA64W (manufactured by ISP, copolymerization ratio = 6/4)
・ Nonionic surfactant Emarex 710 0.01g
Made by Nippon Emulsion Co., Ltd. ・ Ion-exchanged water 6.0g

Preparation of Inorganic Particle Dispersion (1) 6.4 g of synthetic mica Somasif ME-100 (manufactured by Corp Chemical) is added to 193.6 g of ion-exchanged water, and the average particle size (laser scattering method) is 3 μm using a homogenizer. Dispersed until The aspect ratio of the obtained dispersed inorganic particles was 100 or more.

<Exposure and printing>
The obtained lithographic printing plate precursor was exposed to a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi. The exposure image includes a thin line chart. The obtained exposed original plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. Dampening water (EU-3 (Effect manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water and ink, printing was performed at a printing speed of 6000 sheets per hour.

<Evaluation>
In general, in the case of a negative lithographic printing plate precursor, when the exposure amount is small, the degree of cure of the image recording layer is low, and when the amount of exposure is large, the degree of cure is high. If the image recording layer has a too low degree of curing, the printing durability of the lithographic printing plate will be low, and the reproducibility of small dots and fine lines will be poor. On the other hand, when the degree of cure of the image recording layer is high, the printing durability is high, and the reproducibility of small dots and fine lines is good.
In this example, as shown below, the negative lithographic printing plate precursors 1 to 10 and 1 ′ obtained above were evaluated for printing durability and fine line reproducibility under the same exposure conditions described above. It was used as an index of sensitivity of the lithographic printing plate precursor. That is, it can be said that the sensitivity of the lithographic printing plate precursor is higher as the number of printed sheets in printing durability is higher and the fine line width in fine line reproducibility is thinner.

(1) On-machine developability After starting printing as described above, after printing 100 sheets, the number of printing papers required until a print with no ink stains on the non-image area on the printing paper was counted. The number of developed images. The smaller the number, the higher the on-press developability.

(2) Fine line reproducibility As described above, after 100 sheets were printed and it was confirmed that a printed matter free from ink stains in the non-image area was obtained, 500 sheets were continuously printed. A thin line chart of the 600th printed material (charts with 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 60, 80, 100 and 200 μm fine lines exposed) with a 25X magnifier The fine line reproducibility was evaluated by observing and the fine line width reproduced with ink without interruption. The results are shown in Table 3.

(3) Printing durability After printing for fine line reproducibility evaluation as described above, printing was further continued. As the number of printed sheets was increased, the image recording layer was gradually worn out and the ink acceptability was lowered, so that the ink density in the printing paper was lowered. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The results are shown in Table 3.

  From the above results, in Comparative Examples using graft polymers C-1 and C-2 having no ethylenically unsaturated bonds in the molecule, on-press developability is good, but fine line reproducibility and printing durability are poor. In contrast, the lithographic printing plate precursor of the present invention using a graft polymer having an ethylenically unsaturated bond in the molecule has not only good on-press developability but also fine line reproducibility and printing durability. It turns out that the property is also excellent. Therefore, it can be said that the lithographic printing plate precursor of the present invention is excellent in sensitivity.

[Examples 11 to 15, Comparative Examples 3 and 4]
An image recording layer coating solution (2) having the following composition was bar-coated on the same support as used in Example 1, and then oven-dried at 100 ° C. for 60 seconds to obtain a dry coating amount of 1.0 g / m ^2. An image recording layer was formed to obtain a lithographic printing plate precursor. Subsequently, the protective layer coating solution (1) having the above composition is bar-coated on the image recording layer and oven-dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. The lithographic printing plate precursors 11 to 15 and the lithographic printing plate precursors 3 ′ and 4 ′ were obtained.

The image recording layer coating solution (2) was obtained by mixing and stirring the following photosensitive solution (1) and microcapsule solution (1) immediately before coating.
Photosensitive solution (1)
・ 0.1 g of the above polymerization initiator (1)
・ The following infrared absorber (2) 0.02 g
・ Polymerizable monomer, Aronix M-215 0.385 g
(Toa Gosei Co., Ltd.)
・ 0.044 g of the above fluorosurfactant (1)
・ 0.162 g of graft polymer listed in Table 4
・ Propylene glycol monomethyl ether 8.609g
・ Methyl ethyl ketone 1.091g
Microcapsule liquid (1)
・ Microcapsule synthesized as follows (1) 2.640 g
・ Water 2.425g

(Synthesis of microcapsule (1))
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75% ethyl acetate solution) 10 g, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 6 0.000 g, Piionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) 0.12 g was dissolved in 16.67 g of ethyl acetate. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The microcapsule solution thus obtained was diluted with distilled water so that the solid content concentration was 15% by mass. The average particle size was 0.2 μm.

  The lithographic printing plate precursor thus obtained was exposed, printed and evaluated in the same manner as in Example 1. The results are shown in Table 4.

From the above results, even in the lithographic printing plate precursor using microcapsules in the image recording layer, the lithographic printing plate precursor of the present invention has a graft polymer C- having no ethylenically unsaturated bond in the molecule.
From Comparative Example 3 and Comparative Example 4 using 1 and C-2, it can be seen that fine line reproducibility and printing durability are excellent.

Claims (3)

  It comprises an image recording layer containing a graft polymer having a hydrophilic main chain and a hydrophobic segment and an infrared absorber on a support, and the graft polymer has at least one ethylenically unsaturated bond in the molecule. After the lithographic printing plate precursor is mounted on a printing press and imagewise exposed with a laser or imagewise exposed with a laser, it is mounted on a printing press and the lithographic printing plate precursor is oily. A lithographic printing method in which an ink and an aqueous component are supplied to remove an infrared unexposed portion of an image recording layer and printing is performed. The lithographic printing method according to claim 1, wherein the graft polymer has an ethylenically unsaturated bond as at least one group selected from the group of the following general formulas (1) to (3).

(In the formula, X and Y each independently represent an oxygen atom, a sulfur atom or —N—R ^12. Z represents an oxygen atom, a sulfur atom, —N—R ¹² or a phenylene group. R ^{1 to} R ^12. Each independently represents a hydrogen atom or a monovalent substituent.) The lithographic printing method according to claim 1, wherein the image recording layer contains a microcapsule .