JP2010052179A - Original plate of lithographic printing plate and its plate manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate of a lithographic printing plate which is capable of image recording by laser beams and favorable in ink sticking properties, and a plate manufacturing method. <P>SOLUTION: The original plate of the lithographic printing plate has an image recording layer and a protective layer in tis order on a support and contains an aluminum salt in the protective layer. The aluminum salt is preferably expressed by a general formula (I) or a general formula (II) (in which R<SP>1</SP>is a univalent organic group; R<SP>2</SP>-R<SP>6</SP>are hydrogen atoms etc.; X<SP>-</SP>is an anion; and W is a divalent organic linkage group). The original plate is preferably developable on a machine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate precursor and a plate making method thereof. Specifically, the present invention relates to a lithographic printing plate precursor capable of image recording with a laser and capable of on-press development and a plate making method thereof.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in 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). As described above, a difference in ink adhesion is caused on the surface of a lithographic printing plate, and after ink is applied only to an image portion, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, 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. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer corresponding to the image portion remains, and the unnecessary image recording layer corresponding to the non-image portion is removed with an alkaline developer. Alternatively, the lithographic printing plate is obtained by dissolving and removing with an organic solvent-containing developer and exposing the surface of the hydrophilic support to form a non-image portion to form a non-image portion.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is necessary after exposure. However, such additional wet processing is unnecessary or Simplification is cited as one of the issues. 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 simple plate making method, an image recording layer that can remove an unnecessary portion of the image recording layer in a normal printing process is used. A method called on-press development has been proposed in which unnecessary portions are 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 of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. There is a method in which after the force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket.

  On the other hand, in recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread, and various new image output methods corresponding to such digitization technology will be 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.

In the simplification of the plate-making work as described above, a system using an image recording layer and a light source that can be handled in a bright room or under a yellow light is preferable from the viewpoint of ease of work.
As such a laser light source, a solid-state laser such as a semiconductor laser and a YAG laser that emits infrared light having a wavelength of 760 to 1200 nm is extremely useful because a high-power and small-sized laser can be obtained at low cost. . A UV laser can also be used.

  As an on-press development type lithographic printing plate precursor for recording an image with an infrared laser, for example, Patent Document 1 discloses that an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is hydrophilic. A lithographic printing plate precursor provided on a support 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.

  Patent Documents 2 and 3 describe lithographic printing plate precursors containing microcapsules encapsulating a polymerizable compound on a hydrophilic support. Furthermore, Patent Document 4 describes a lithographic printing plate precursor in which a photosensitive layer (image recording layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support.

The method using the polymerization reaction as described above 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 the polymer fine particles. In order to prevent polymerization inhibition due to oxygen therein and adhesion of the back surface due to stickiness of the polymerizable compound, it was necessary to provide an oxygen-blocking protective layer (overcoat layer) on the image recording layer.
As a protective layer used for this purpose, it is generally known that a water-soluble resin such as polyvinyl alcohol is used, and Patent Document 5 discloses an on-press development type lithographic plate provided with a protective layer using a modified polyvinyl alcohol. A printing plate precursor is described. However, in the on-press development type printing plate, in order to improve developability, the image recording layer is designed to have high water permeability, and a protective layer mainly composed of a water-soluble resin is provided thereon. For this reason, there is a problem that the ink deposition property at the time of printing is insufficient.
Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A JP 2005-271284 A

  Accordingly, an object of the present invention is to provide a lithographic printing plate precursor having good ink deposition properties. Another object of the present invention is to provide a plate making method of a lithographic printing plate precursor having good ink depositing properties.

1. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, wherein the protective layer contains an azinium salt.
2. 2. The lithographic printing plate precursor as described in 1 above, wherein the azinium salt is represented by the following general formula (I) or general formula (II).

In General Formula (I) and General Formula (II), R ¹ represents a monovalent organic group, and R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom or a halogen atom. Or a monovalent organic group. X ⁻ represents an anion. W represents a divalent organic linking group.

3. 3. The lithographic printing plate precursor as described in 1 or 2 above, wherein the protective layer contains an inorganic stratiform compound.
4). The lithographic printing plate as described in any one of 1 to 3 above, wherein the image recording layer comprises (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound. A printing plate master.
5). 5. The lithographic printing plate precursor as described in any one of 1 to 4 above, wherein the image recording layer contains a hydrophobizing precursor.
6). 1 to 5 above, wherein the image recording layer is an image recording layer capable of forming an image by supplying printing ink and fountain solution on a printing machine after exposure to remove an unexposed portion. The lithographic printing plate precursor as described in any one of the above.
7). The lithographic printing plate precursor as described in 6 above is mounted on a printing machine after image exposure or image exposure after mounting on a printing machine, and on-press development processing is performed by supplying printing ink and fountain solution. Characteristic plate making method.

  According to the present invention, it is possible to provide a lithographic printing plate precursor from which good ink deposition properties can be obtained. Further, according to the present invention, it is possible to provide a plate making method of a lithographic printing plate precursor having good ink fillability.

[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention is a lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, and is characterized by containing an azinium salt in the protective layer. Further, the lithographic printing plate precursor according to the invention is preferably developable on the machine by supplying printing ink and fountain solution.

(Protective layer)
In general, the protective layer has not only a function of suppressing an image formation inhibition reaction by its oxygen blocking ability, but also functions such as prevention of scratches in the image recording layer and prevention of ablation at the time of high-illuminance laser exposure.
The protective layer of the present invention contains an azinium salt. Inclusion property can be improved by containing an azinium salt. Moreover, it is preferable that the protective layer of this invention contains an inorganic stratiform compound. As described in JP-A-2005-119273, the inorganic layered compound has a remarkable effect of improving printing durability. However, in the case of on-press development, it has been found that it has a defect that it remains after development and deteriorates the ink deposition property. The inclusion of the azinium salt in the protective layer of the present invention brings about an excellent effect of improving the inking property even when an inorganic layered compound is used.
Hereinafter, components constituting the protective layer will be described.

<Azinium salt>
An azinium salt has an azine ring which is a six-membered ring containing a nitrogen atom in its structure, and includes a pyridinium salt, a diazinium salt, and a triazinium salt. Furthermore, azinium salts include one or more aromatic rings condensed with an azine ring, and include, for example, quinolinium salts, isoquinolinium salts, benzoazinium salts, naphthaziniums, and the like.
The azinium salt used in the present invention is not particularly limited as long as it is an azinium salt, but a pyridinium salt is preferable. Among them, a compound represented by the following general formula (I) or (II) is more preferable.

In the above formula, R ¹ represents a monovalent organic group, and R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom, a halogen atom, or a monovalent organic group. . Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom. Among these, a chlorine atom and a bromine atom are preferable. X ⁻ represents an anion. W represents a divalent organic linking group.

  Examples of the monovalent organic group include an amino group substituted by a group having a carbon atom, a carbonyl group substituted by a group having a carbon atom, an oxy group substituted by a group having a carbon atom, and a carbon atom. Substituted by a thioether group substituted by a group, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclic group, a sulfonyl group substituted by a group having a carbon atom, or a group having a carbon atom A sulfinyl group, a phosphono group substituted by a group having a carbon atom, a phosphonato group substituted by a group having a carbon atom, and the like.

Examples of the alkyl group represented by R ^{1 to} R ⁶ include linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms. Among these, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, and a cyclic alkyl group having 5 to 10 carbon atoms are more preferable. Specific examples thereof include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group, octadecyl group. , Eicosyl 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, cyclohexyl group, cyclopentyl group And 2-norbornyl group.

Examples of the alkenyl group represented by R ^{1 to} R ⁶ include alkenyl groups having 2 to 20 carbon atoms. Among these, an alkenyl group having 2 to 10 carbon atoms is preferable, and an alkenyl group having 2 to 8 carbon atoms is more preferable. The alkenyl group may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group. A cyclic alkyl group is preferred. Specific examples of the alkenyl group include, for example, vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 1-pentenyl group, 1-hexenyl group, 1-octenyl group, 1-methyl-1-propenyl group, 2-methyl-1-propenyl group, 2-methyl-1-butenyl group, 2-phenyl-1-ethenyl group, 2-chloro-1-ethenyl group, allyl group, 2-butenyl group, 2-methylallyl group, 2 -Methyl-3-butenyl group, 3-methyl-2-butenyl group, etc. are mentioned.

Examples of the alkynyl group represented by R ^{1 to} R ⁶ include alkynyl groups having 2 to 20 carbon atoms. Among these, an alkynyl group having 2 to 10 carbon atoms is preferable, and an alkynyl group having 2 to 8 carbon atoms is more preferable. Specific examples thereof include ethynyl group, 1-propynyl group, 1-butynyl group, phenylethynyl group, trimethylsilylethynyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group and the like.

Examples of the aryl group represented by R ^{1 to} R ⁶ include a benzene ring, a group in which 2 to 3 benzene rings form a condensed ring, and a group in which a benzene ring and a 5-membered unsaturated ring form a condensed ring. Can be mentioned. Specific examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group. Among these, a phenyl group and a naphthyl group are more preferable.

Examples of the aralkyl group represented by R ^{1 to} R ⁶ include those in which the above aryl group is substituted on the above alkyl group. Specific examples include benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, and the like.

The heterocyclic group represented by R ^{1 to} R ⁶ is preferably a 3- to 8-membered heterocyclic group, more preferably a 3- to 6-membered heterocyclic group containing a nitrogen atom, an oxygen atom, or a sulfur atom. Preferably, a 5- or 6-membered heterocyclic group containing a nitrogen atom, an oxygen atom, or a sulfur atom is more preferable. Specifically, pyrrole ring group, furan ring group, thiophene ring group, benzopyrrole ring group, benzofuran ring group, benzothiophene ring group, pyrazole ring group, isoxazole ring group, isothiazole ring group, indazole ring group, benzoiso Xazole ring group, benzoisothiazole ring group, imidazole ring group, oxazole ring group, thiazole ring group, benzimidazole ring group, benzoxazole ring group, benzothiazole ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, Pyridazine ring group, pyrimidine ring group, pyrazine ring group, phthalazine ring group, quinazoline ring group, quinoxaline ring group, acylidin ring group, phenanthridine ring group, carbazole ring group, purine ring group, pyran ring group, piperidine ring group, Piperazine ring group, morpholine ring group, indole ring group, indolizine ring group, Road ring group, a cinnoline ring group, an acridine ring group, a phenothiazine ring group, a tetrazole ring group, a triazine ring group, and the like.

The thioether group substituted with a group having a carbon atom represented by R ^{2 to} R ⁶ is preferably a thioether group having 1 to 30 carbon atoms, more preferably a thioether group having 1 to 20 carbon atoms, More preferred are 1 to 10 thioether groups.
Specific examples thereof include alkylthio groups such as methylthio group, ethylthio group and cyclohexylthio group, arylthio groups such as phenylthio group, and the like.

As the oxy group (R ⁰⁶ O—) substituted by a group having a carbon atom represented by R ^{2 to} R ⁶ , R ⁰⁶ is a group composed of a monovalent nonmetallic atomic group excluding a hydrogen atom. Can be used. Preferred substituted oxy groups include alkoxy groups, aryloxy groups, acyloxy groups, carbamoyloxy groups, N-alkylcarbamoyloxy groups, N-arylcarbamoyloxy groups, N, N-dialkylcarbamoyloxy groups, N, N-diarylcarbamoyloxy groups. Groups, N-alkyl-N-arylcarbamoyloxy groups, alkylsulfoxy groups, arylsulfoxy groups, phosphonooxy groups, and phosphonatoxy groups. Examples of the alkyl group and aryl group in these include the alkyl groups, substituted alkyl groups, aryl groups, and substituted aryl groups described above. Examples of the acyl group (R ⁰⁷ CO—) in the acyloxy group include those in which R ⁰⁷ is an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group mentioned above. Among these substituents, an alkoxy group, an aryloxy group, an acyloxy group, and an arylsulfoxy group are more preferable. Specific examples of preferred substituted oxy groups include methoxy, ethoxy, propyloxy, isopropyloxy, butyloxy, pentyloxy, hexyloxy, dodecyloxy, benzyloxy, allyloxy, phenethyloxy, Carboxyethyloxy group, methoxycarbonylethyloxy group, ethoxycarbonylethyloxy group, methoxyethoxy group, phenoxyethoxy group, methoxyethoxyethoxy group, ethoxyethoxyethoxy group, morpholinoethoxy group, morpholinopropyloxy group, allyloxyethoxyethoxy group, Phenoxy group, tolyloxy group, xylyloxy group, mesityloxy group, mesityloxy group, cumenyloxy group, methoxyphenyloxy group, ethoxyphenyloxy group, chlorophenyl Alkoxy group, bromophenyl group, acetyloxy group, benzoyloxy group, naphthyloxy group, a phenylsulfonyloxy group, a phosphonooxy group, phosphonatoxy group, and the like.

The amino group substituted by the group having a carbon atom represented by R ^{2 to} R ⁶ may be a substituted amino group including an amide group. As the substituted amino group (R ⁰⁸ NH—, (R ⁰⁹ ) (R ⁰¹⁰ ) N—) including an amide group, R ⁰⁸ , R ⁰⁹ , and R ⁰¹⁰ are a group composed of a monovalent nonmetallic atomic group excluding a hydrogen atom. Can be used. R ⁰⁹ and R ⁰¹⁰ may combine to form a ring. Preferred examples of the substituted amino group include an N-alkylamino group, an N, N-dialkylamino group, an N-arylamino group, an N, N-diarylamino group, an N-alkyl-N-arylamino group, an acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido group, N ′, N′-diarylureido group N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N′-alkyl-N′-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N ′, '-Dialkyl-N'-aryl, ureido group, N'-aryl-N-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, aryl Roxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group Is mentioned. Examples of the alkyl group and aryl group include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group, such as acylamino group, N-alkylacylamino group, and N-arylacylamino. ^{R 07} groups definitive acyl group ^(R 07 CO-) are as described above. Of these, more preferred are an N-alkylamino group, an N, N-dialkylamino group, an N-arylamino group, and an acylamino group. Specific examples of preferred substituted amino groups include methylamino group, ethylamino group, diethylamino group, morpholino group, piperidino group, pyrrolidino group, phenylamino group, benzoylamino group, acetylamino group and the like.

As the sulfonyl group (R ⁰¹¹ —SO ₂ —) substituted with a group having a carbon atom represented by R ^{1 to} R ⁶ , a group in which R ⁰¹¹ is a monovalent nonmetallic atomic group can be used. More preferable examples include an alkylsulfonyl group, an arylsulfonyl group, and a substituted or unsubstituted sulfamoyl group. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Specific examples of such a substituted sulfonyl group include butylsulfonyl group, phenylsulfonyl group, chlorophenylsulfonyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfuryl group. A famoyl group, an N-alkyl-N-arylsulfamoyl group, and the like.

As the carbonyl group (R ⁰¹³ —CO—) substituted by a group having a carbon atom represented by R ^{1 to} R ⁶ , a group in which R ⁰¹³ is a monovalent nonmetallic atomic group can be used. Preferred examples of the substituted carbonyl group include 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 may be mentioned. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Among these, more preferred substituted carbonyl groups include formyl, acyl, carboxyl, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, N-alkylcarbamoyl, N, N-dialkylcarbamoyl, N-ary. A rucarbamoyl group can be mentioned, and even more preferred are a formyl group, an acyl group, an alkoxycarbonyl group and an aryloxycarbonyl group. Specific examples of preferred substituted carbonyl groups include formyl group, acetyl group, benzoyl group, carboxyl group, methoxycarbonyl group, ethoxycarbonyl group, allyloxycarbonyl group, dimethylaminophenylethenylcarbonyl group, methoxycarbonylmethoxycarbonyl group, N -Methylcarbamoyl group, N-phenylcarbamoyl group, N, N-diethylcarbamoyl group, morpholinocarbonyl group and the like.

As the sulfinyl group (R ⁰¹⁴ —SO—) substituted with a group having a carbon atom represented by R ^{1 to} R ⁶ , a group in which R ⁰¹⁴ is a monovalent nonmetallic atomic group can be used. Preferred examples include alkylsulfinyl group, arylsulfinyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl. Group, N-alkyl-N-arylsulfinamoyl group. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Of these, more preferred examples include an alkylsulfinyl group and an arylsulfinyl group. Specific examples of such a substituted sulfinyl group include a hexylsulfinyl group, a benzylsulfinyl group, and a tolylsulfinyl group.

A phosphono group substituted by a group having a carbon atom represented by R ^{1 to} R ⁶ means a group in which one or two of the hydroxyl groups on the phosphono group are substituted by another organic oxo group. Includes the above-mentioned dialkylphosphono group, diarylphosphono group, alkylarylphosphono group, monoalkylphosphono group, and monoarylphosphono group. Of these, dialkylphosphono groups and diarylphosphono groups are more preferred. Specific examples thereof include a diethyl phosphono group, a dibutyl phosphono group, a diphenyl phosphono group, and the like.

Of the foregoing substituted phosphono group and a phosphonato group substituted with a group having a carbon atom represented by R ¹ to R ^6, a conjugated base anion group but was replaced a hydroxyl group on one organic oxo group, specifically Examples include the conjugate bases of the aforementioned monoalkylphosphono group (—PO ₃ H (alkyl)) and monoarylphosphono group (—PO ₃ H (aryl)).

X < ^- > is an arbitrary anion and is preferably an acid anion. Specific examples include a halogen atom anion, BF ₄ ⁻ , BCl ₄ ⁻ , ZnCl ₄ ⁻ , SbCl ₆ ⁻ , FeCl ₄ ⁻ , GaCl ₄ ⁻ , GaBr ₄ ⁻ , AlI ₄ ⁻ , AlCl ₄ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ , PF ₆ ⁻ , BPh ₄ ⁻ , condensed polynuclear sulfonate anions such as naphthalene-1-sulfonic acid, anthracene-1-sulfonic acid, anthraquinone sulfonate anion, anthracene sulfonate anion, sulfonate group-containing dyes ( An anion having a sulfonic acid group and a chromogenic atomic group), but is not limited thereto.
Among these, X ⁻ is preferably an inorganic anion or a strong acid counter anion, more preferably PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ or C ₄ F ₉ SO ₃ ⁻ , and most preferably PF ₆ ^−. .

  The divalent organic linking group represented by W is a polyvalent organic group composed of non-metallic atoms, from 1 to 60 carbon atoms, from 0 to 10 nitrogen atoms, from 0 Those composed of up to 50 oxygen atoms, 0 to 100 hydrogen atoms, and 0 to 20 sulfur atoms are preferred. More specific examples include organic linking groups constituted by the following structures alone or in combination.

  The organic linking group represented by W may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, a hydroxy group, a carboxyl group, a sulfonate group, a nitro group, a cyano group, and an amide group. Amino group, alkyl group, alkenyl group, alkynyl group, aryl group, substituted oxy group, substituted sulfonyl group, substituted carbonyl group, substituted sulfinyl group, sulfo group, phosphono group, phosphonato group, silyl group, heterocyclic group, etc. Can be mentioned.

  Among these, the organic linking group represented by W is more preferably a methylene chain having 20 or less carbon atoms and a group containing 1 to 5 oxygen atoms in the methylene chain.

  Specific examples of the compound represented by the general formula (I) or the general formula (II) include the following.

  These compounds are preferably added in an amount of 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and 0.9 to 15% by mass in the total solid content in the protective layer. More preferably. Within this range, good ink landing properties can be obtained without deteriorating stain resistance and printing durability.

<Other components used in the protective layer>
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 property desired for the protective layer is 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 protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

As the polymer component used in 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, Examples thereof include water-soluble polymers such as starch 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.

  Examples of relatively useful materials among the above materials include 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 esters, ethers, and acetals as long as they contain a substantial amount of unsubstituted vinyl alcohol units 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 modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC manufactured by Kuraray Co., Ltd. , 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.
Moreover, as modified polyvinyl alcohol, all made by Kuraray Co., Ltd., KL-318, KL-118, KM-618, KM-118, SK-5102 having anion-modified sites, C having a cation-modified site. -318, C-118, CM-318, M-205, M-115 with terminal thiol modification sites, MP-103, MP-203, MP-102, MP-202 with terminal sulfide modification sites, high grade Examples thereof include HL-12E and HL-1203 having an ester-modified site with a fatty acid at the end, and R-1130, R-2105, R-2130 having other reactive silane-modified sites.

The protective layer preferably contains an inorganic layered compound, that is, a compound that is an inorganic compound, has a layered structure, and has a flat plate shape. By using such an inorganic layered compound in combination, the oxygen barrier property is further increased and the printing durability is remarkably improved. Further, the film strength of the protective layer is further improved and scratch resistance is improved, and matting properties can be imparted to the protective layer.
As an inorganic layered compound, for example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH
, F, O) ₂ [where A is any of Li, K, Na, Ca, Mg, organic cation, and B and C are any of Fe (II), Fe (III), Mn, Al, Mg, V) D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.

Among the mica compounds, natural mica includes muscovite, soda mica, phlogopite, biotite and sericite. Synthetic mica includes non-swellable 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-based 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 mica compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, saponite, 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 has a shortage of positive charge, and in order to compensate for it, Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts, sulfonium salts, etc. Adsorbs organic cation cations. These layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have a strong tendency and are useful in the present invention. In particular, swellable synthetic mica is preferably used from the viewpoint of availability and quality uniformity.

  The shape of the layered compound is a flat plate, and from the viewpoint of diffusion control, the thinner the better, the larger the plane size as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. . 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, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  As for the particle diameter of the layered compound, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. When the particle size is 0.3 μm or more, it is preferable that the permeation of oxygen and moisture is sufficiently suppressed and the effect can be sufficiently exhibited. Moreover, when it is 20 μm or less, the dispersion stability in the coating solution is sufficient, and stable coating can be performed, which is preferable. 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 in this way, the coating film strength is improved and oxygen and moisture permeation can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

Next, an example of a general dispersion method when a layered compound is 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. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled and has very good storage stability.
When preparing a coating solution for a protective layer using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

  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 a protective layer. Even when a plurality of kinds of inorganic layered compounds are used in combination, it is preferable that the total amount of these inorganic layered compounds is compatible with the above-described mass ratio.

  As other additives for the protective layer, for example, glycerin, dipropylene glycol, propionamide, cyclohexanediol, sorbitol and the like are added in an amount corresponding to several mass% with respect to the water-soluble or water-insoluble polymer to impart flexibility. be able to. Moreover, well-known additives, such as a water-soluble (meth) acrylic polymer and a water-soluble plasticizer, can be added for improving the physical properties of the film.

Further, the protective layer in the present invention is formed by using a coating solution for a protective layer as described later. This coating solution is used for improving the adhesion with the image recording layer and the stability over time of the coating solution. Known additives may be added.
That is, the protective layer coating solution includes an anionic surfactant, a nonionic surfactant, a cationic surfactant, and a fluorosurfactant for improving coating properties, specifically, 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. These surfactants can be added in an amount of 0.1 to 100% by mass relative to the water-soluble or water-insoluble 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, a sensitizer such as the low-molecular nitrogen compound or ammonium salt-containing polymer described later can be added to the protective layer. With these additions, a further effect of improving the inking property can be obtained. The amount of addition of the sensitizer to the protective layer is preferably in the range of 0.5 to 30% by mass.

Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved. Further, for the purpose of controlling the slipperiness of the outermost surface of the lithographic printing plate precursor, it may contain spherical inorganic fine particles added to the image recording layer described later. Preferred examples of the inorganic fine particles include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, and a mixture thereof. The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 50 nm to 3 μm. 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 40% by mass or less, and more preferably 20% by mass or less, based on the total solid content of the protective layer.

The protective layer is formed by applying and drying a protective layer coating solution prepared by dispersing or dissolving the protective layer component in a solvent on the image recording 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 applying the protective 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. .
Specifically, for example, when the protective layer is formed, a blade coating method, an air knife coating method, a gravure coating method, a roll coating coating method, a spray coating method, a dip coating method, a bar coating method, or the like is used.

The coating amount of the protective 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, and most preferably 0. It is in the range of 02 to 1 g / m ² .

(Image recording layer)
The image recording layer used in the present invention is preferably capable of forming an image after exposure by supplying printing ink and fountain solution on a printing machine to remove unexposed portions.
Typical image forming mechanisms contained in the image recording layer and capable of on-press development include (1) (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound. A mode in which an image portion is cured by using a polymerization reaction, and (2) (A) an infrared absorber and (D) a hydrophobized precursor, and heat fusion or thermal reaction of the hydrophobized precursor An embodiment in which a hydrophobic region (image portion) is formed by using it can be mentioned. Further, a mixture of the above two embodiments may be used. For example, (1) the polymerization type image recording layer may contain (D) a hydrophobized precursor, or (2) the hydrophobized precursor type may contain a polymerizable compound. Especially, the photopolymerization aspect containing (A) infrared absorber, (B) radical polymerization initiator, and (C) polymeric compound is preferable.
Hereinafter, each component that can be included in the image recording layer will be sequentially described.

<(A) Infrared absorber>
The lithographic printing plate precursor according to the invention preferably contains an infrared absorber in the image recording layer when an image is formed using a laser emitting infrared rays having a wavelength of 760 to 1200 nm as a light source.
The infrared absorber has a function of converting the absorbed infrared light into heat and a function of being excited by the infrared light and transferring electrons and / or energy to a radical polymerization initiator described later. 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.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, The methine dyes described in Japanese Laid-Open Patent Publication Nos. 58-181690 and 58-194595, Japanese Patent Laid-Open Nos. 58-112793, 58-224793, 59-48187, Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, squarylium dyes described in JP-A-58-112792, and the like; And cyanine dyes described in British Patent No. 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- No. 41363, 59-84248, 59-84249, 59-146063, 59-146061, and pyrine compounds described in JP-A-59-216146. And pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds shown 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).
In the present invention, other preferred examples of infrared absorbing dyes include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Among these dyes, cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes are preferable. 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 formula (i), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group represented by the following structural formula. 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 a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a selenium atom. R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, a substituted amino group and a halogen atom, X _a ^- is Z _a to be described later ^- is the same definition.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. In view of the storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered member. It is particularly preferable that a ring or 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. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, an alkoxy group having 12 or less carbon atoms, a hydrocarbon group having 12 or less carbon atoms, and 12 carbon atoms. Most preferred are not more than alkoxy groups. 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. Preferable substituents include an alkoxy group having 12 or less carbon atoms, a carboxyl group, and a sulfo group, and an alkoxy group having 12 or less carbon atoms is most preferable. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ^- represents a counter anion. However, when the cyanine dye represented by formula (i) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate, from the storage stability of the coating solution for the image recording layer. Acid ions, tetrafluoroborate ions, hexafluorophosphate ions, and aryl sulfonate ions.

Specific examples of cyanine dyes 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. Can do.
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 Applications of Metal Soap” (Yokoshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

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

  As a method for dispersing the pigment, a known dispersion technique used for 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 other components, or may be added to another image recording layer provided. However, when a lithographic printing plate precursor is prepared, image recording is performed. The layer is added so that the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm is in the range of 0.3 to 1.2 by the reflection measurement method. Preferably, it is the range of 0.4-1.1. 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.

  If the content of the (A) infrared absorber in the image recording layer in the present invention is described in terms of a specific addition amount, 0.1 to 10.0% by mass of the total solid content of the image recording layer is preferable, and more preferable. Is 0.5-5.0 mass%.

<(B) Radical polymerization initiator>
The (B) radical polymerization initiator used in the present invention is a compound that generates radicals by light, heat, or both, and initiates and accelerates polymerization of the polymerizable compound (C). As the radical polymerization initiator that can be used in the present invention, a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, and the like can be used.
Examples of the radical polymerization initiator in the present invention include (a) an organic halide, (b) a carbonyl compound, (c) an azo polymerization initiator, (d) an organic peroxide, (e) a metallocene compound, (f ) Azide compound, (g) hexaarylbiimidazole compound, (h) organic borate compound, (i) disulfone compound, (j) oxime ester compound, (k) onium salt compound.

  (A) Specific examples of organic halides include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP-A 48-36281, JP-A 55-32070, JP-A 60-239736, JP-A 61-169835, JP-A 61-169837, JP-A 62-58241, JP Sho 62-212401, JP-A 63-70243, JP-A 63-298339, M.S. P. Examples include compounds described in Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”, and particularly preferable examples include oxazole compounds substituted with a trihalomethyl group and s-triazine compounds.

  More preferred are s-triazine derivatives and oxadiazole derivatives to which at least one mono, di, or trihalogen-substituted methyl group is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6- (Trichloromethyl) -s-triazine, 2- (p-bromophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-fluorophenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-trifluoromethylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dichlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (2,6-difluorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dibromophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (4-biphenylyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4'-chloro-4-biphenylyl) -4,6 Bis (trichloromethyl) -s-triazine, 2- (p-cyanophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-acetylphenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-ethoxycarbonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-phenoxycarbonylphenyl) -4,6-bis (trichloromethyl)- s-triazine, 2- (p-methylsulfonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-dimethylsulfoniumphenyl) -4,6-bis (trichloromethyl) -s- Triazine tetrafluoroborate, 2- (2,4-difluorophenyl) -4,6-bis (trichloromethyl) -s-tria Gin, 2- (p-diethoxyphosphorylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (4-hydroxyphenylcarbonylamino) phenyl] -4,6-bis (trichloro) Methyl) -s-triazine, 2- [4- (p-methoxyphenyl) -1,3-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis ( Trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4, 6-bis (trichloro) Methyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bi (Trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6 -Tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy -4,6-bis (tribromomethyl) -s-triazine, 2- (o-methoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- (3,4-epoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- [1-phenyl-2- (4-methoxyphenyl) vinyl] -5-trichloromethyl-1,3 4-oxadiazole, 2- (p-hydroxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- (3,4-dihydroxystyryl) -5-trichloromethyl-1,3 4-oxadiazole, 2- (pt-butoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole and the like.

  (B) Examples of the carbonyl compound include benzophenone, Michler ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenylketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1-hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenol) E) Acetophenone derivatives such as ketone, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, Examples thereof include benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  (C) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

  (D) Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert -Butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5- Dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) Hexane, 2,5-oxanoyl Peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, dimethoxyisopropylperoxide Oxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butylperoxyacetate, tert-butylperoxypivalate, tert-butylperoxyneodecanoate, tert-butylperoxyocta Noate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- ( t- Xylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogendiphthalate), carbonyldi (t-hexyl) Peroxydihydrogen diphthalate) and the like.

  (E) As metallocene compounds, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705 Various titanocene compounds described in JP-A-5-83588, for example, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1- , Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl , Di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-pen Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoro Phen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3 4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyrrol-1-yl) phen-1-yl, Examples thereof include iron-arene complexes described in 304453 and JP-A-1-152109.

(F) Examples of the azide compound include 2,6-bis (4-azidobenzylidene) -4-methylcyclohexanone.
(G) Examples of hexaarylbiimidazole compounds include JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Various compounds described in the specification, specifically 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o- Bromophenyl)) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2, 2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5 , 5'-tetraphenylbiimidazole, 2 , 2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′- Examples include tetraphenylbiimidazole and 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole.

  (H) Examples of the organic borate compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188865, JP-A-9-188686, JP-A-9-188710, JP 2000-131837, JP 2002-107916, JP 2764769, JP 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”. Organoboron salts described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, and organic boron oxosulfonium complexes described in JP-A-6-157563, JP-A-175554, JP-A-6-1755 No. 3, an organoboron iodonium complex, an organoboron phosphonium complex described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, Specific examples include organoboron transition metal coordination complexes such as JP-A-7-306527 and JP-A-7-292014.

  (I) Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.

  (J) Examples of the oxime ester compound include J.M. C. S. Perkin II (1979) 1653-1660), J. MoI. C. S. Examples include Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, JP-A 2000-66385, and JP-A 2000-80068. Specific examples thereof include compounds represented by the following structural formula.

  (K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055 and 4,069,056, phosphonium salts described in European Patent Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201, 2-150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297,442 U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,73 No. 4,444, 2,833,827, German Patent Nos. 2,904,626, 3,604,580, and 3,604,581 . V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.

In particular, the above oxime ester compounds, diazonium salts, iodonium salts, and sulfonium salts are preferable in terms of reactivity and stability. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
Preferred onium salts for the present invention are onium salts represented by the following general formulas (RI-I) to (RI-III).

In the formula (RI-I), Ar ¹¹ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and 1 carbon atom. -12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C12 An alkylamino group, a C1-C12 dialkylamino group, a C1-C12 alkylamide group or arylamide group, a carbonyl group, a carboxyl group, a cyano group, a sulfonyl group, a C1-C12 thioalkyl group, A C1-C12 thioaryl group is mentioned. Z ^11- represents a monovalent anion, a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, stability From the viewpoint of the visibility of the printout image, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, and sulfinate ions are preferable.

In the formula (RI-II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents have 1 to 12 carbon atoms. An alkyl group, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, a halogen atom An alkylamino group having 1 to 12 carbon atoms, a dialkylamino group having 1 to 12 carbon atoms, an alkylamide group or arylamide group having 1 to 12 carbon atoms, a carbonyl group, a carboxyl group, a cyano group, a sulfonyl group, and 1 carbon atom -12 thioalkyl group and C1-C12 thioaryl group are mentioned. Z ^21- represents a monovalent anion, a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, stability From the viewpoint of the visibility of the printout image, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable.

In the formula (RI-III), R ³¹ , R ³² and R ³³ each independently represents an aryl group having 20 or less carbon atoms, an alkyl group, an alkenyl group or an alkynyl group which may have 1 to 6 substituents. In view of reactivity and stability, an aryl group is desirable. Preferred examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, Aryloxy group having 1 to 12 carbon atoms, halogen atom, alkylamino group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12 carbon atoms, alkylamide group or arylamide group having 1 to 12 carbon atoms, carbonyl group, carboxyl Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms. Z ^31- represents a monovalent anion, which is a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, and is stable. From the viewpoint of visibility of the printout image, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable, and more preferable are JP-A-2001-343742. And the carboxylate ions described in JP-A No. 2002-148790 are particularly preferable.

  Examples of onium salts that can be suitably used as radical polymerization initiators in the present invention will be given below, but the present invention is not limited thereto.

(B) The radical polymerization initiator is not limited to the above, but particularly from the viewpoint of reactivity and stability, (a) an organic halide, particularly, a triazine-based initiator included therein, (j) oxime Diazonium salts, iodonium salts, and sulfonium salts included in the ester compounds and (k) onium salt compounds are more preferable. Among these radical polymerization initiators, from the viewpoint of improving the visibility of the printout image in combination with an infrared absorber, it is an onium salt and an inorganic anion such as PF ₆ ⁻ , BF as a counter ion. ₄ ^- such as those having preferred. Furthermore, diaryliodonium is preferred as the onium salt because of its excellent color development.

These (B) radical polymerization initiators may be used alone or in combination of two or more.
(B) The radical polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content constituting the image recording layer. % Can be added. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained.
In addition, these (B) radical polymerization initiators may be added to the same layer as other components, or another layer may be provided in or adjacent to the image recording layer. .

<(C) Polymerizable compound>
The polymerizable compound (C) that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has at least one terminal ethylenically unsaturated bond, preferably two or more. It is chosen from the compound which has. 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, ie dimers, trimers and oligomers, or mixtures thereof and their (co) polymers.

  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 hydroxy group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or 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.

  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, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. 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.

  Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxy group are also suitable. Specific examples of such compounds are described in, for example, Japanese Patent Publication No. 48-41708. Containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxy group represented by the following general formula (A) to a polyisocyanate compound having two or more isocyanate groups in the molecule A vinyl urethane compound etc. are mentioned.

^{_{CH 2 = C (R 19)}} COOCH 2 CH (R 20) OH formula (A)
(However, R ¹⁹ and R ²⁰ each represent H or CH _3. )

  Further, urethane acrylates as described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 And urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418. Furthermore, 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 are used. Depending on the case, 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, Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, specific unsaturated compounds described in each publication, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also included. Can 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) 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 portion, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether). It is also effective to adjust both sensitivity and strength by using a compound of the type).
In addition, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, radical polymerization initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the support or the above-described protective layer.

In the present invention, the polymerizable compound (C) is preferably used in the range of 5 to 50% by mass, and more preferably 8 to 35% by mass with respect to the nonvolatile component in the image recording layer.
In addition, the use method of the addition polymerizable compound can arbitrarily select an appropriate structure, blending, and addition amount from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration / coating method such as undercoating or overcoating can be carried out.

  The image recording layer of the present invention can contain the following components as required.

<(D) Hydrophobized precursor>
The hydrophobized precursor in the present invention means fine particles that can convert the image recording layer to hydrophobic when heat is applied. The fine particles are preferably at least one particle selected from hydrophobic thermoplastic polymer fine particles, heat-reactive polymer fine particles, microcapsules enclosing a hydrophobic compound, and microgel.

Hydrophobic thermoplastic polymer fine particles include Research Disclosure No. 1 of January 1992. 33303, hydrophobic thermoplastic polymer fine particles described in JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250 and European Patent No. 931647 are suitable. Can be cited as
Specific examples of the polymer constituting such polymer fine particles include homopolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, and vinylcarbazole. Mention may be made of polymers or copolymers or mixtures thereof. Among them, more preferred are polystyrene and polymethyl methacrylate.

The average particle diameter of the hydrophobic thermoplastic polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm.
Examples of the method for synthesizing hydrophobic thermoplastic polymer fine particles having the above-mentioned particle size that can be used as a hydrophobizing precursor include an emulsion polymerization method and a suspension polymerization method. In addition, these compounds are dissolved in a water-insoluble organic solvent. There is a method (solution-dispersion method) in which this is mixed and emulsified with an aqueous solution containing a dispersant, and further heated to solidify into fine particles while flying off the organic solvent.

  Examples of the heat-reactive polymer fine particles used in the present invention include polymer fine particles having a heat-reactive group, and these form a hydrophobized region by cross-linking by a heat reaction and a functional group change at that time.

  The thermally reactive group in the polymer fine particle having a thermally reactive group used in the present invention may be any functional group that performs a reaction as long as a chemical bond is formed, but is an ethylenically unsaturated group that performs a radical polymerization reaction. Group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationically polymerizable group (for example, vinyl group, vinyloxy group, etc.), isocyanate group that performs addition reaction or its block, epoxy group, vinyloxy group And a functional group having an active hydrogen atom as a reaction partner thereof (for example, an amino group, a hydroxy group, a carboxyl group, etc.), a carboxyl group for performing a condensation reaction, a hydroxy group or an amino group as a reaction partner, a ring-opening addition reaction Suitable acid anhydride and reaction partner amino group or hydroxy group It can gel.

Introduction of these functional groups into the polymer fine particles may be performed at the time of polymerization, or may be performed using a polymer reaction after the polymerization.
When introduced at the time of polymerization, the monomer having the above functional group is preferably subjected to emulsion polymerization or suspension polymerization. Specific examples of the monomer having the above functional group include allyl methacrylate, allyl acrylate, vinyl methacrylate, vinyl acrylate, 2- (vinyloxy) ethyl methacrylate, p-vinyloxystyrene, p- {2- (vinyloxy) ethyl} styrene, Block isocyanate with glycidyl methacrylate, glycidyl acrylate, 2-isocyanatoethyl methacrylate or alcohol thereof, block isocyanate with 2-isocyanatoethyl acrylate or alcohol, 2-aminoethyl methacrylate, 2-aminoethyl acrylate, 2- Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctional acrylate, Such as functional methacrylates include, but are not limited to.

  In the present invention, a copolymer of these monomers and a monomer that is copolymerizable with these monomers and does not have a thermally reactive group can also be used. Examples of the copolymer monomer having no heat-reactive group include styrene, alkyl acrylate, alkyl methacrylate, acrylonitrile, vinyl acetate, and the like. It is not limited to.

  Examples of the polymer reaction used when the introduction of the thermally reactive group is carried out after polymerization include the polymer reaction described in International Publication No. 96/34316 pamphlet.

  Among the polymer fine particles having a heat-reactive group, those in which the polymer fine particles are coalesced by heat are preferable, and those having a hydrophilic surface and being dispersed in water are particularly preferable. The coating contact angle (water droplets) produced by applying only polymer fine particles and drying at a temperature lower than the solidification temperature is higher than the contact angle (water droplets) produced by drying at a temperature higher than the solidification temperature. It is preferable to lower. In order to make the surface of the polymer fine particles hydrophilic in this manner, a hydrophilic polymer or oligomer such as polyvinyl alcohol or polyethylene glycol or a hydrophilic low molecular weight compound may be adsorbed on the surface of the polymer fine particles. However, the surface hydrophilization method is not limited to this.

  The solidification temperature of the polymer fine particles having these thermoreactive groups is preferably 70 ° C. or higher, but more preferably 100 ° C. or higher in view of the stability over time. The average particle size of the polymer fine particles is preferably 0.01 to 2.0 μm, more preferably 0.05 to 2.0 μm, and most preferably 0.1 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

  Examples of the microcapsules used in the present invention include constituents of the image recording layer (the components (A) to (C) described above) as described in JP-A Nos. 2001-277740 and 2001-277742. All or a part of these are encapsulated in microcapsules. The constituent components of the image recording layer can also be contained outside the microcapsules. Furthermore, the image recording layer containing microcapsules is preferably a mode in which hydrophobic constituent components are encapsulated in microcapsules and hydrophilic constituent components are contained outside the microcapsules.

  In this invention, the aspect containing a crosslinked resin particle, ie, a microgel, may be sufficient. This microgel can contain a part of the above-mentioned (A) to (C) in and / or on the surface thereof. In particular, the microgel has (C) a polymerizable compound on the surface thereof to form a reactive microgel. This aspect is particularly preferable from the viewpoints of image formation sensitivity and printing durability.

  As a method for microencapsulating or microgelling the constituent components of the image recording layer, known methods can be applied.

  For example, as a method for producing a microcapsule, US Pat. No. 2,800,547, US Pat. No. 2,800,498, a method using coacervation, US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, U.S. Pat. Nos. 3,418,250 and 3,660,304, by precipitation of polymers, and U.S. Pat. No. 3,796,669. Urea-formaldehyde found in US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 4,087,376 and US Pat. No. 4,089,802. System or urea formaldehyde-resorcino A method using a wall-based wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as described in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method by monomer polymerization, spraying 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 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. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into the below-mentioned binder polymer.

On the other hand, as a method for preparing the microgel, granulation by interfacial polymerization described in JP-B-38-19574 and JP-A-42-446, as described in JP-A-5-61214, etc. It is possible to utilize granulation by non-aqueous dispersion polymerization. However, it is not limited to these methods.
As the method using the interfacial polymerization, the above-described known microcapsule production method can be applied.

  Preferred microgels used in the present invention are those granulated by interfacial polymerization and having three-dimensional crosslinking. From such a viewpoint, the material to be used is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and polyurea and polyurethane are particularly preferable.

  The average particle size of the microcapsules or microgel 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 content of the hydrophobizing precursor is preferably in the range of 5 to 90% by mass in terms of solid content concentration, and the image area strength can be improved by addition.

<Binder polymer>
In the image recording layer of the present invention, a binder polymer can be used in order to improve the film strength of the image recording layer. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, polystyrene resins, novolac phenolic resins, polyester resins, synthetic rubbers, natural rubbers. Is mentioned. Particularly preferred are acrylic resins, polyvinyl acetal resins, and polyurethane resins.
These binder polymers may have 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.

  Moreover, it is preferable that the binder polymer used by this invention has a hydrophilic group. The hydrophilic group contributes to imparting on-press developability to the image recording layer. In particular, the coexistence of a crosslinkable group and a hydrophilic group makes it possible to achieve both printing durability and developability.

  Examples of the hydrophilic group include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, an alkylene oxide structure, a hydroxypropyl group, a polyoxyethyl group, a polyoxypropyl group, an amino group, an aminoethyl group, and an aminopropyl group. , Ammonium group, amide group, carboxymethyl group, sulfo group, phosphoric acid group and the like, and preferred are amide group, hydroxy group, polyoxyethyl group, alkylene oxide structure, etc., and the following general formula (ii) The alkylene oxide structure represented by is most preferable. It is preferable to have this alkylene oxide structure in the side chain.

式（ii）中、Ｒは水素原子またはメチル基を表し、ａは１、３または５であり、ｎは１〜９の整数を表す。ｎは好ましくは１〜８の整数であり、より好ましくは１〜７の整数、さらに好ましくは１〜６の整数、最も好ましくは２〜４の整数である。

In formula (ii), R represents a hydrogen atom or a methyl group, a is 1, 3 or 5, and n represents an integer of 1 to 9. n is preferably an integer of 1 to 8, more preferably an integer of 1 to 7, more preferably an integer of 1 to 6, and most preferably an integer of 2 to 4.

In order to impart a hydrophilic group to the acrylic resin, a hydrophilic monomer may be copolymerized. Specific examples of the copolymerization monomer having a hydrophilic group include acrylamide, methacrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide, N-vinylpyrrolidone, N-vinylacetamide, N-acryloylmorpholine, 2-hydroxyethyl. Acrylate, 2-hydroxyethyl methacrylate, polyoxyethylene monomethacrylate, polyoxyethylene monoacrylate, polyoxypropylene monomethacrylate, polyoxypropylene monoacrylate, (meth) acrylic acid ester of polyoxyethylene monoalkyl ether, polyoxypropylene mono And (meth) acrylic acid esters of alkyl ethers.
These can be used alone or in combination of two or more. The content of these structural units having a hydrophilic group is preferably 1 to 85 mol%, particularly preferably 5 to 5 mol% in the polymer compound. 70 mol%.

Furthermore, a lipophilic group having a carbon atom such as an alkyl group, an aryl group, an aralkyl group, or an alkenyl group can be introduced into the present invention to the extent that the effect is not impaired. The inking property can be controlled by these.
In order to impart lipophilicity to the acrylic resin, a lipophilic monomer may be copolymerized. The copolymerization monomer is selected from, for example, acrylic esters, methacrylic esters, N, N-2 substituted acrylamides, N, N-2 substituted methacrylamides, styrenes, acrylonitriles, methacrylonitriles, and the like. Monomer.

  Specifically, for example, acrylic esters such as alkyl acrylate (the alkyl group preferably has 1 to 20 carbon atoms) (specifically, for example, methyl acrylate, ethyl acrylate, acrylic Propyl butyl, butyl acrylate, amyl acrylate, ethyl hexyl acrylate, octyl acrylate, tert-octyl acrylate, chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate , Pentaerynuritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, etc.), aryl acrylate (e.g., phenyl Methacrylic acid esters (eg, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl). Methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, Glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate Styrene) such as methyl methacrylate, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, butyl, aryl methacrylate (for example, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, etc.), styrene, alkyl styrene, etc. Styrene, hexyl styrene, cyclohexyl styrene, decyl styrene, benzyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, etc.), alkoxy styrene (for example, methoxy styrene, 4-methoxy-3-methyl styrene, dimethoxy) Styrene), halogen styrene (e.g., chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlors) Styrene, pentachlorostyrene, prom styrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, etc.), acrylonitrile, Examples include methacrylonitrile.

  The binder polymer preferably has a mass average molar mass (Mw) of 5000 or more, more preferably 10,000 to 300,000, and the number average molar mass (Mn) is preferably 1000 or more. More preferably, it is 2000-250,000. The polydispersity (Mw / Mn) is preferably 1.1-10.

  The binder polymer can be obtained by purchasing a commercial product or synthesizing it by a known method.

The content of the binder polymer is 5 to 90% by mass, preferably 5 to 80% by mass, and 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.
Further, (C) the polymerizable compound and the binder polymer are preferably used in an amount of 0.5 / 1 to 4/1 by mass ratio.

  Specific examples of the binder polymer used in the present invention are shown below, but the present invention is not limited thereto.

<Other ingredients>
The image recording layer in the invention may further contain other components as required.
Hereinafter, other components used in the image recording layer of the present invention will be described.

(1) Surfactant A surfactant can be used in the image recording layer in the invention in order to improve the coated surface state.
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Among these, fluorosurfactants are preferable.

  Examples of the fluorosurfactant include a fluorosurfactant 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 5% by mass with respect to the total solid content of the image recording layer.

(2) Colorant In the image recording layer of the present invention, 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.
When these colorants are used, it is easy to distinguish between an image area after image formation and a non-image area, so it is preferable to add them.
The amount added is 0.01 to 10% by mass with respect to the total solid content of the image recording layer.

(3) Print-out agent To the image-recording layer according to the invention, a compound that is discolored by an acid or a radical can be added to form a print-out 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, Malachite Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Industry 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 preferably 0.01 to 10% by mass with respect to the solid content of the image recording layer.

(4) Polymerization inhibitor In the image recording layer of the present invention, a small amount of a thermal polymerization inhibitor is added in order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer. It is preferable to add.
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-tert-butylphenol), and 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.

(5) Higher fatty acid derivatives, etc. In order to prevent polymerization inhibition by oxygen, higher fatty acid derivatives such as behenic acid and behenic acid amide are added to the image recording layer in the present invention, and the drying process after coating is performed. May be unevenly distributed on the surface of the image recording layer.
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.

(6) Plasticizer The image recording layer in the 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.

(7) Inorganic fine particles The image recording layer in the present invention may contain inorganic fine particles in order to improve the cured film strength and the on-press developability.
Suitable inorganic fine particles include, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof. These 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 μm 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 40% by mass or less, and more preferably 30% by mass or less, based on the total solid content of the image recording layer.

(8) Low molecular weight hydrophilic compound The image recording layer in the invention may contain a low molecular weight hydrophilic compound because it improves the on-press developability without reducing the printing durability.
Examples of the low molecular weight hydrophilic compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid Acids and salts thereof, organic sulfamic acids such as alkylsulfamic acid and salts thereof, organic sulfates such as alkylsulfuric acid and alkylethersulfuric acid and salts thereof, Organic phosphonic acids and their salts such as Ruhosuhon acid, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof such as amino acids, betaine compounds, and the like.
Among these, organic sulfonic acids, organic sulfamic acids, organic sulfates such as sodium salts and lithium salts of organic sulfates, and betaine compounds are preferably used.

  Specific examples of organic sulfonates include sodium normal butyl sulfonate, sodium isobutyl sulfonate, sodium sec-butyl sulfonate, sodium tert-butyl sulfonate, sodium normal pentyl sulfonate, and sodium 1-ethylpropyl sulfonate. , Sodium normal hexyl sulfonate, sodium 1,2-dimethylpropyl sulfonate, sodium 2-ethylbutyl sulfonate, sodium 2-ethylhexyl sulfonate, sodium cyclohexyl sulfonate, sodium normal heptyl sulfonate, sodium normal octyl sulfonate, tert -Sodium octyl sulfonate, sodium normal nonyl sulfonate, sodium allyl sulfonate, 2-methylallyl sulfonic acid Thorium, sodium 4- [2- (2-butyloxy-ethoxy) -ethoxy] -butane-1-sulfonate, sodium 4- [2- (2-hexyloxy-ethoxy) -ethoxy] -butane-1-sulfonate 4- {2- [2- (2-ethyl) hexyloxy-ethoxy] -ethoxy} -butane-1-sulfonic acid sodium, 4- [2- (2-decyloxy-ethoxy) -ethoxy] -butane-1 Sodium sulfonate, 4- {2- [2- (2-butyloxy-ethoxy) -ethoxy] -ethoxy} -butane-1-sulfonic acid sodium, 4- [2- {2- [2- (2-ethyl) ) Hexyloxy-ethoxy] -ethoxy} -ethoxy] -butane-1-sulfonate, sodium benzenesulfonate, sodium p-toluenesulfonate , Sodium p-hydroxybenzenesulfonate, sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate isophthalate, disodium 1,3-benzenedisulfonate, trisodium 1,3,5-benzenetrisulfonate, Sodium p-chlorobenzenesulfonate, sodium 3,4-dichlorobenzenesulfonate, sodium 1-naphthylsulfonate, sodium 2-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonate, 2 , 6-Naphthalenedisulfonic acid disodium, 1,3,6-naphthalene trisulfonic acid trisodium, and lithium salt exchangers thereof.

  Specific examples of the organic sulfamate include sodium normal butyl sulfamate, sodium isobutyl sulfamate, sodium tert-butyl sulfamate, sodium normal pentyl sulfamate, sodium 1-ethylpropyl sulfamate, sodium normal hexyl sulfamate, Examples include sodium 1,2-dimethylpropylsulfamate, sodium 2-ethylbutylsulfamate, sodium cyclohexylsulfamate, and lithium salt exchangers thereof.

  These compounds have a small hydrophobic part structure and almost no surface-active action, and are clearly distinguished from the above-mentioned surfactants in which long-chain alkyl sulfonates and long-chain alkyl benzene sulfonates are used favorably. .

  As the organic sulfate, a compound represented by the following general formula (iii) is particularly preferably used.

  In the general formula (iii), R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, m represents an integer of 1 to 4, and X represents sodium, potassium, or lithium. .

  R is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, or an aryl group having 20 or less carbon atoms. Can be mentioned. These groups may further have a substituent. In that case, examples of the substituent that can be introduced include linear, branched or cyclic alkyl groups having 1 to 12 carbon atoms, and those having 1 to 12 carbon atoms. Examples include an alkenyl group, an alkynyl group having 1 to 12 carbon atoms, a halogen atom, and an aryl group having 20 or less carbon atoms.

  Preferred examples of the compound represented by the general formula (iii) include sodium oxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, dioxy Ethylene-2-ethylhexyl ether lithium sulfate, sodium trioxyethylene-2-ethylhexyl ether sulfate, sodium tetraoxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene hexyl ether sulfate, sodium dioxyethylene octyl ether sulfate, dioxyethylene Examples include sodium lauryl ether sulfate. Of these, the most preferred compounds include sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, and lithium dioxyethylene-2-ethylhexyl ether sulfate.

  The amount of the low molecular weight hydrophilic compound added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, they are 1 mass% or more and 10 mass% or less, More preferably, they are 2 mass% or more and 8 mass% or less. In this range, good on-press developability and printing durability can be obtained.

  As the betaine compound, compounds represented by general formula (iv) and general formula (v) are preferably used.

R ^{1 to} R ³ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkenyl group, an alkynyl group, a cycloalkyl group or an aryl group, and may be substituted with a hydroxy group or an amino group. Z represents an alkylene group having 1 to 4 carbon atoms, and may be substituted with a hydroxy group. At least two of R ^{1 to} R ³ and Z may be bonded to form a heterocyclic ring.

By containing these compounds in the image recording layer, it is possible to improve the on-press developability without reducing the printing durability. Among them, it is desirable R ¹ to R ³ is a heterocyclic 5-6 membered ring two are bonded alkyl group having 1 to 3 carbon atoms, or R ¹ to R ³ and Z,, in particular, R ¹ ~ quaternary ammonium skeleton R ³ is a methyl or ethyl group, or R ¹ to R ³ and two of pyrrolidine skeleton bonded to form a ring of Z,, piperidine skeleton, a pyridine skeleton, those having a imidazoline skeleton desirable.

Specific compounds of the general formula (iv) are exemplified below, but the present invention is not limited to the following.

Specific compounds of the general formula (v) are exemplified below, but the present invention is not limited to the following.

これらの有機スルホン酸、有機スルファミン酸、有機硫酸塩およびベタイン化合物は、疎水性部分の構造が小さくて界面活性作用がほとんどないため、湿し水が画像記録層露光部（画像部）へ浸透して画像部の疎水性や皮膜強度を低下させることがなく、画像記録層のインキ受容性や耐刷性を良好に維持できる。

Since these organic sulfonic acids, organic sulfamic acids, organic sulfates and betaine compounds have a small hydrophobic portion structure and almost no surface active action, the fountain solution penetrates into the image recording layer exposed portion (image portion). Thus, the ink receptivity and printing durability of the image recording layer can be maintained satisfactorily without lowering the hydrophobicity and film strength of the image area.

  The amount of the compound represented by formula (iv) or (v) added to the image recording layer is preferably 0.1% by mass or more and 10% by mass or less of the total solid content of the image recording layer. More preferably, it is 0.2 mass% or more and 5 mass% or less, More preferably, it is 0.4 mass% or more and 2 mass% or less. Within these ranges, good on-press developability and printing durability can be obtained.

Low molecular weight hydrophilic compounds such as the above organic sulfonic acids, organic sulfamic acids, organic sulfates, and betaine compounds have a small hydrophobic portion structure and almost no surface-active action. The ink receptivity and printing durability of the image recording layer can be maintained satisfactorily without penetrating into the (image area) and reducing the hydrophobicity and film strength of the image area.
These low molecular weight hydrophilic compounds may be used alone or in combination of two or more.

(9) Grease-sensitizing agent When the above-mentioned protective layer contains an inorganic stratiform compound, the image recording layer may contain a phosphonium compound, a nitrogen-containing low molecular weight compound, an ammonium group-containing polymer, etc. A sensitizer can be used. Further, different types of sensitizers may be used in combination.
These compounds function as a surface coating agent (greasy sensitizer) for the inorganic layered compound, and prevent a decrease in the inking property during printing by the inorganic layered compound.

  Suitable phosphonium compounds include compounds represented by the following general formula (K1) described in JP-A-2006-297907 or the following general formula (K2) described in JP-A-2007-50660.

In Formula (K1), R ₁ ~R ₄ are each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio Represents a group, a heterocyclic group or a hydrogen atom. At least two of R _{1 to} R ₄ may be bonded to form a ring. X ⁻ represents a counter anion.

In General Formula (K2), Ar _{1 to} Ar ₆ each independently represents an aryl group or a heterocyclic group, L represents a divalent linking group, X ⁿ⁻ represents an n-valent counter anion, and n Represents an integer of 1 to 3, and m represents a number satisfying nxm = 2. Here, as the aryl group, phenyl group, naphthyl group, tolyl group, xylyl group, fluorophenyl group, chlorophenyl group, bromophenyl group, methoxyphenyl group, ethoxyphenyl group, dimethoxyphenyl group, methoxycarbonylphenyl group, dimethylaminophenyl A group and the like are preferable. Examples of the heterocyclic group include a pyridyl group, a quinolyl group, a pyrimidinyl group, a thienyl group, and a furyl group. L represents a divalent linking group. 6-15 are preferable and, as for carbon number in a coupling group, More preferably, it is a C6-C12 coupling group. Preferred examples of X ⁿ⁻ include halide anions such as Cl ⁻ , Br ⁻ and I ⁻ , toluenesulfonate, naphthalene-1,7-disulfonate, naphthalene-1,3,6-trisulfonate, and 5-benzoyl. Examples include sulfonate anions such as -4-hydroxy-2-methoxybenzene-4-sulfonate, carboxylate anions, sulfate anions, sulfate anions, PF ₆ ⁻ , BF ₄ ⁻ , and perchlorate anions. Of these, a sulfonate anion is particularly preferable.

  Specific examples of the phosphonium compound represented by the general formula (K1) or (K2) are shown below.

  In addition to the above-mentioned phosphonium compound, the following nitrogen-containing low molecular weight compounds can be mentioned as the sensitizers preferably used in the present invention. Preferred nitrogen-containing low molecular weight compounds include compounds having the structure of the following general formula (K3).

In the formula, R ^{1 to} R ⁴ each independently represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. At least two of R ^{1 to} R ⁴ may be bonded to form a ring. X ⁻ is an anion, PF ₆ ⁻ , BF ₄ ⁻ , or an organic sulfone having a substituent selected from an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aralkyl group, and a heterocyclic group Indicates an acid anion.

That the nitrogen-containing low molecular weight compound for use in the present invention include quaternary ammonium salts wherein at least one amine salt is a hydrogen atom R ¹ to R ^4, and R ¹ to R ⁴ is not any hydrogen atom . In addition, imidazolinium salts represented by the following general formula (K4), benzimidazolinium salts represented by the following general formula (K5), pyridinium salts represented by the following general formula (K6), and the following general formula (K7) The quinolinium salt structure may be used.

In the above formula, R ⁵ and R ^{6 each} represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. X < ^- > is an anion and is synonymous with X < ^- > of the said general formula (K3).

  Among these, quaternary ammonium salts and pyridinium salts are preferably used. Specific examples thereof are shown below.

  The amount of the phosphonium compound or nitrogen-containing low molecular weight compound added to the image recording layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, based on the solid content of the image recording layer. 5% by mass is most preferred. Within these ranges, good ink fillability during printing can be obtained.

  As the sensitizer used in the present invention, the following ammonium group-containing polymers are also preferred. The ammonium group-containing polymer may be any polymer as long as it has an ammonium group in its structure, but is preferably a polymer containing structures of the following general formulas (K8) and (K9) as repeating units.

(Wherein R ¹¹ and R ¹² each independently represent a hydrogen atom or a methyl group. R ² represents an alkylene group which may have a substituent, an alkyleneoxy group which may have a substituent, etc. It represents a divalent linking group, R ^31, R ³² and R ³³ each independently represent an alkyl group or an aralkyl group having 1 to 10 carbon atoms .X ^{- is, F -, Cl -, Br} -, I - Benzenesulfonic acid anion, methyl sulfate anion, ethyl sulfate anion, propyl sulfate anion, butyl sulfate anion that may be branched, amyl sulfate anion that may be branched, PF ₆ ⁻ , BF _{4 ^{-, B (C 6 F 5}} ) 4 - is .R ⁴ represents an organic or inorganic anion such as an alkyl group having 1 to 21 carbon atoms, an aralkyl group, an aryl _{group, - (C 2 H 4 O} ) n - R ⁵ or _{(C 3 H 6 O) n} -R 5, Represents, R ⁵ is .n represents a hydrogen atom, a methyl group or an ethyl group is 1 or 2.)

  The ammonium salt-containing polymer contains at least one structural unit represented by general formula (K8) and general formula (K9), but either one may be two or more, and both are 2 There may be more than species. Although the ratio of both structural units is not limited, The molar ratio is particularly preferably 5:95 to 80:20. Moreover, this polymer may contain another copolymerization component within the range which can ensure the effect of this invention.

  The ammonium salt-containing polymer has a reduced specific viscosity (unit: cSt / g / ml) determined by the following measurement method, preferably in the range of 5 to 120, more preferably in the range of 10 to 110. The range of 15-100 is especially preferable.

<Measurement method of reduced specific viscosity>
Weigh 3.33 g of 30% polymer solution (1 g as solid content) into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is put into an Ubbelohde reduced viscosity tube (viscosity constant = 0.010 cSt / s), and the time for flowing at 30 ° C. is measured. Time to pass (second) ") is calculated by the usual method.

The content of the ammonium salt-containing polymer is preferably 0.0005% by mass to 30.0% by mass, more preferably 0.001% by mass to 20.0% by mass with respect to the total solid content of the image recording layer. 002% by mass to 15.0% by mass is most preferable. Within this range, good inking properties can be obtained. The ammonium salt-containing polymer may be further contained in the protective layer.
Specific examples of the ammonium salt-containing polymer are shown below.

<Formation of image recording layer>
The image recording layer in the present invention is formed by preparing or applying a coating solution by dispersing or dissolving the necessary components described above in a solvent, and coating and drying the coating solution.
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-butyllactone, 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.

  In the image recording layer of the present invention, a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents are prepared, and coating and drying are repeated a plurality of times to form a multilayered image recording layer. It is also possible.

Further, coating amount of the image-recording layer on the support after drying (solid content) may be varied according to the intended purpose, generally 0.3 to 3.0 g / m ² is preferred. 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.

(Undercoat layer)
In the planographic printing plate precursor, an undercoat layer (sometimes referred to as an intermediate layer) is provided between the image recording layer and the support, if necessary. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. Contributes to improvement. In addition, in the case of infrared laser exposure, since the undercoat layer functions as a heat insulating layer, the heat generated by exposure does not diffuse to the support and can be used efficiently, so that the sensitivity can be increased. is there. Below, the component etc. which are used for the undercoat of this invention are demonstrated.

Specific examples of the undercoat layer compound include a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in JP-A-10-282679, and JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of gazette publication are mentioned suitably.
As the most preferable undercoat layer compound, a polymer resin having an adsorptive group, a hydrophilic group, and a crosslinkable group can be mentioned. This polymer resin is preferably formed by copolymerization of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

The polymer resin for the undercoat layer preferably has an adsorptive group on the surface of the hydrophilic support. The presence or absence of adsorptivity to the surface of the hydrophilic support can be determined, for example, by the following method.
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, after the support coated with the test compound is sufficiently washed with an easily soluble solvent, the residual amount of the test compound that has not been removed by washing is measured to calculate the support adsorption amount. 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. A compound having a support adsorptivity is a compound that remains at 1 mg / m ² or more even after the washing treatment as described above.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) present on the surface of the hydrophilic support, or a functional group (for example, a hydroxy group) and a chemical bond (for example, an ionic bond, It is a functional group capable of causing a hydrogen bond, a coordinate bond, and a bond due to 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 the acid group are phenolic hydroxy group, carboxyl group, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ , —COCH _2. COCH ₃ is mentioned. Of these, —OPO ₃ H ₂ and PO ₃ H ₂ are particularly preferable. 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. Among these, an ammonium group, a phosphonium group, and a sulfonium group are preferable, an ammonium group and a phosphonium group are more preferable, and an ammonium group is most preferable.

  As a particularly preferred example of the monomer having an adsorptive group used when synthesizing a polymer resin suitable as a compound for the undercoat layer, a compound represented by the following general formula (U1) or general formula (U2) can be given. It is done.

In the general formulas (U1) and (U2), 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 each independently preferably 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 preferably, it is most preferably a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
Z is a functional group adsorbed on the surface of the hydrophilic support, and the adsorptive functional group is as described above.

In the general formulas (U1) and (U2), L is a single bond or 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—, R is an aliphatic group, an aromatic group Group or heterocyclic group) or a combination with carbonyl (—CO—).

The divalent aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the divalent aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The divalent aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. Furthermore, the divalent aliphatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an aromatic group, and a heterocyclic group.
The number of carbon atoms of the divalent aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. In addition, the divalent aromatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an aliphatic group, an aromatic group, and a heterocyclic group.
The divalent heterocyclic group preferably has a 5-membered or 6-membered ring as a heterocycle. In addition, another heterocyclic ring, an aliphatic ring or an aromatic ring may be condensed with the heterocyclic ring. The divalent heterocyclic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an oxo group (═O), a thioxo group (═S), an imino group (═NH ), A substituted imino group (= N—R, R is an aliphatic group, an aromatic group or a heterocyclic group), an aliphatic group, an aromatic group, or a heterocyclic group.

In the present invention, 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 General Formula (U1), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom.
In general formula (U2), Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is linked to Y to form a quaternary pyridinium group, Z itself is adsorbable, so Z is not essential and Z may be a hydrogen atom.

  Examples of typical compounds represented by general formula (U1) or general formula (U2) are shown below.

  The polymer resin suitable as the undercoat layer compound preferably has a hydrophilic group. Examples of the hydrophilic group include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, and a hydroxypropyl group. Preferred examples include a group, a polyoxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, an ammonium group, an amide group, a carboxymethyl group, a sulfo group, and a phosphoric acid group. Of these, a sulfo group exhibiting high hydrophilicity is preferable.

Specific examples of the monomer having a sulfo group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t-butylsulfonic acid, Examples include 2-acrylamido-2-methylpropanesulfonic acid, sodium salt of (3-acryloyloxypropyl) butylsulfonic acid, and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and handling of synthesis.
These are suitably used when synthesizing a polymer resin suitable as a compound for the undercoat layer.

  The polymer resin for the undercoat layer in the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to make the polymer resin for the undercoat layer crosslinkable, a crosslinkable functional group such as an ethylenically unsaturated bond is introduced into the side chain of the polymer, or the polar substituent of the polymer resin is countercharged. Or a compound having an ethylenically unsaturated bond may be introduced by forming a salt structure.

  An example of a polymer having an ethylenically unsaturated bond in the side chain of the molecule is an ester or amide polymer of acrylic acid or methacrylic acid, wherein the ester or amide residue (-COOR or CONHR R) is ethylene. The polymer which has an ionic unsaturated bond can be mentioned.

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 or 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 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 of the polymer resin 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 polymer resin 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 polymer resin. 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.

The polymer resin for the undercoat layer preferably has a mass average molar mass of 5000 or more, more preferably 10,000 to 300,000, and a number average molar mass of 1000 or more is preferable. More preferably, it is ˜250,000. The polydispersity (mass average molar mass / number average molar mass) is preferably 1.1 to 10.
The polymer resin 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.

  The polymer resin for undercoating may be used alone or in combination of two or more.

  The undercoat layer of the present invention can contain a secondary or tertiary amine or a polymerization inhibitor in order to prevent contamination of the raw plate (unexposed lithographic printing plate precursor) over time. Secondary or tertiary amines include imidazole, 4-dimethylaminopyridine, 4-dimethylaminobenzaldehyde, tris (2-hydroxy-1-methyl) amine, 1,4-diazabicyclo [2,2,2] octane ( DABCO), 1,5,7-triazabicyclo [4,4,0] dec-5-ene, 1,8-diazabicyclo [5,4,0] undec-7-ene, 1,10-phenanthroline, 1 , 8-bis (dimethylamino) naphthalene, 4,4′-bis (dimethylamino) biphenyl, diphenylamine, 1,3-diphenylguanidine, 4-phenylpyridine, N, N′-ethylenebis (2,2,5,5) 5-tetramethylpyrrolidine) and the like.

Examples of the polymerization inhibitor include known thermal polymerization inhibitors. Among them, preferred polymerization inhibitors are phenolic hydroxy group-containing compounds, quinone compounds, N-oxide compounds, piperidine-1-oxyl free radical compounds, pyrrolidine-1-oxyl free radical compounds, N-nitrosophenylhydroxyl. It is a compound selected from the group consisting of amines, diazonium compounds, cationic dyes, sulfide group-containing compounds, nitro group-containing compounds, and transition metal compounds such as FeCl ₃ and CuCl ₂ . Of the above compounds, quinone compounds are particularly preferred. Specific examples of the quinone compounds include 1,4-benzoquinone, 2,3,5,6-tetrahydroxy-1,4-benzoquinone 2,5-dihydroxy-1,4-benzoquinone, chloranil, and 2,3-dichloro. -5,6-dicyano-1,4-benzoquinone, naphthoquinone, 2-fluoro-1,4-naphthoquinone, 2-hydroxyethyl-1,4-naphthoquinone, anthraquinone, 1,2,4-trihydroxyanthraquinone, 2, And 6-dihydroxyanthraquinone.

  The amount of these compounds added to the undercoat layer is preferably from 10 to 90% by mass, more preferably from 20 to 80% by mass, and most preferably from 30 to 70% by mass, based on the components of the undercoat layer.

In addition, a compound having an amino group or a functional group having a polymerization inhibiting ability and a group that interacts with the aluminum support surface can also be used as a compound that is effective for preventing stains during aging. Examples of groups that interact with the aluminum support surface include trialkoxysilyl groups, onium groups, or phenolic hydroxy 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 CO—, an acid group or a metal salt thereof.

  Examples of the compound having an interaction group between the amino group and the aluminum support surface include a salt of 1,4-diazabicyclo [2,2,2] octane and an acid, 4-aza-1-azoniabicyclo [2,2 , 2] Compound having at least one octane structure (for example, 1-methyl-4-aza-1-azoniabicyclo [2,2,2] octane = p-toluenesulfonate), ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid , Dihydroxyethylethylenediaminediacetic acid, 1,3-propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethyliminodiacetic acid, and the like. As a compound having a functional group having a polymerization inhibiting ability and a group that interacts with the surface of the aluminum support, 2-trimethoxysilylpropylthio-1,4-benzoquinone, 2,5-bis (trimethoxysilylpropylthio)- 1,4-benzoquinone, 2-carboxyanthraquinone, 2-trimethylammonioanthraquinone = chloride and the like.

The undercoat layer coating solution is obtained by dissolving the above-described undercoat polymer resin and necessary additives in an organic solvent (for example, 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.

(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 these, 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.

  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. Moreover, the transcription | transfer method which transfers an uneven | corrugated shape with the roll which provided the unevenness | corrugation in the rolling stage of aluminum can also 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, and 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 / dm 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. However, in order to further improve the adhesiveness with the upper layer, hydrophilicity, dirt resistance, heat insulation and the like. If necessary, it is immersed in an aqueous solution containing a hydrophilic compound and a micropore enlargement treatment or sealing treatment of an anodized film described in JP-A-2001-253181 or JP-A-2001-322365. The surface hydrophilization treatment to be performed can be appropriately selected and performed. Of course, the enlargement process and the sealing process are not limited to those described above, and any conventionally known methods can be performed. For example, as the sealing treatment, in addition to the vapor sealing, a single treatment with fluorinated zirconic acid, a treatment with sodium fluoride, and a vapor sealing with addition of lithium chloride are possible.

  The sealing treatment used in the present invention is not particularly limited, and a conventionally known method can be used. Among them, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and hot water. Sealing treatment is preferred. Each will be described below.

<1> Sealing treatment with an aqueous solution containing an inorganic fluorine compound As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, zirconate fluoride, titanate fluoride, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Of these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

  The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

  It is preferable that the aqueous solution containing an inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that on-machine developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.

  The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by mass or less, and more preferably 5% by mass or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
Further, the temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
Further, the aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
A method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

<2> Sealing treatment with water vapor The sealing treatment with water vapor includes, for example, a method in which pressurized or normal pressure water vapor is contacted with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The pressure of the water vapor is preferably in a range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

<3> Sealing treatment with hot water Examples of the sealing treatment with hot water include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

  The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate methods. In this method, the support is subjected to immersion treatment or electrolytic treatment with an aqueous solution such as sodium silicate. 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 and condensation reaction of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer comprising an inorganic thin film having a surface Preferred. 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 to the image recording layer, good printing durability and good stain resistance can be obtained.

(Back coat layer)
After the surface treatment is performed on the support or after the undercoat layer is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
As the back coat layer, for example, an organic polymer compound described in JP-A-5-45885, an organometallic compound or an inorganic metal compound described in JP-A-6-35174 is hydrolyzed and polycondensed. Preferable examples include a coating layer made of a metal oxide. Of these, the use of silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4, etc. is inexpensive. It is preferable in that it is easily available.

[Plate making method]
The plate making method of the lithographic printing plate precursor according to the present invention includes a step of image exposing the lithographic printing plate precursor, and supplying printing ink and fountain solution without performing any development treatment on the exposed lithographic printing plate precursor. And an on-press development characterized in that an unexposed portion of the lithographic printing plate precursor is removed in the course of the printing step. The imagewise exposure may be performed by first mounting the lithographic printing plate precursor on a printing machine, or the exposed lithographic printing plate precursor may be mounted on a printing machine, and then printing using the printing machine. By supplying ink and fountain solution and printing as it is, on-machine development processing in an early stage of printing, that is, the image recording layer in the unexposed area is removed, and accordingly the hydrophilic support surface is formed. Exposed to become dampening water receiving area and can be printed. As the printing ink and fountain solution, ordinary lithographic printing ink and fountain solution are used.
This will be described in more detail below.

In the present invention, the light source used for image exposure is preferably a laser. Although the laser used for this invention is not specifically limited, The solid laser and semiconductor laser etc. which irradiate infrared rays with a wavelength of 760-1200 nm are mentioned suitably.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In the laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, image exposure is performed after a lithographic printing plate precursor is mounted on a plate cylinder of the printing press.

  After exposing the lithographic printing plate precursor imagewise with an infrared laser, printing with supplying dampening water and printing ink without going through a development process such as a wet development process, the exposed part of the image recording layer The image recording layer cured by exposure forms a printing ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied fountain solution and printing ink, and a hydrophilic surface is exposed in that portion. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area and printing is started.

Here, dampening water or printing ink may be supplied to the printing plate first, but printing is first performed in order to prevent the dampening water from being contaminated by the removed image recording layer components. It is preferable to supply ink. As the fountain solution and printing ink, normal lithographic fountain solution 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.

[Examples 1-16 and Comparative Examples 1-2]

1. Production of lithographic printing plate precursors (1) to (11), (17) (1) Production of support 10% by mass in order to remove rolling oil on the surface of a 0.3 mm thick aluminum plate (material JIS A 1050) After degreasing treatment at 50 ° C. for 30 seconds using an aqueous solution of sodium aluminate, three bundle-planted nylon brushes having a bristle diameter of 0.3 mm and a pumice-water suspension having a median diameter of 25 μm (specific gravity 1.1 g / cm) ^{Using 3} ), the aluminum surface was grained and washed thoroughly with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. At this time, the etching amount of the grained surface 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 source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. 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 nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, the plate was provided with a direct current anodic oxide film having a current density of 15 A / dm ² and a current density of 15 g / m ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, followed by washing with water. It dried and produced the support body (1).
Thereafter, in order to ensure the hydrophilicity of the non-image area, the support (1) was subjected to a silicate treatment at 60 ° C. for 10 seconds using a 2.5 mass% No. 3 sodium silicate aqueous solution. The adhesion amount of Si was 10 mg / m ² . Then, it washed with water and the support body (2) was obtained. 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.

(2) Formation of undercoat layer Next, the following undercoat layer coating solution (1) was applied on the support (2) so that the dry coating amount was 20 mg / m ² , and the oven was set at 100 ° C. Was dried for 30 seconds to prepare a support having an undercoat layer used in the following experiments.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Water 6.15g

(3) Formation of image recording layer The image recording layer coating solution (1) having the following composition was bar-coated on the undercoat layer formed as described above, and then oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount. An image recording layer of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

<Photosensitive solution (1)>
-Binder polymer (1) [the following structure] 0.240 g
Infrared absorber (1) [the following structure] 0.030 g
-Radical polymerization initiator (1) [the following structure] 0.162 g
Polymerizable compound tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate 0.062g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
・ Fluorosurfactant (1) [The following structure] 0.008g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution (1)>
・ Microgel (1) 2.640 g
・ Distilled water 2.425g

  Structure of the binder polymer (1), infrared absorber (1), radical polymerization initiator (1), phosphonium compound (1), low molecular weight hydrophilic compound (1), and fluorine-based surfactant (1) Is as follows.

-Synthesis of microgel (1)-
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by 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 12,000 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 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was designated as the microgel (1). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

(3) Formation of Protective Layer After the protective layer coating solution (1) having the following composition was further bar-coated on the image recording layer, it was oven-dried at 120 ° C. for 60 seconds, and the dry coating amount was 0.15 g / m ^2. The lithographic printing plate precursors (1) to (11) [for Examples 1 to 11] and the lithographic printing plate precursor (17) [for Comparative Example 1] were obtained.

<Coating liquid for protective layer (1)>
・ Inorganic layered compound dispersion (1) 1.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.55 g
-Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd., saponification degree: 81.5 mol%,
Degree of polymerization 500) 6% by weight aqueous solution 0.03 g
・ Nippon Emulsion Co., Ltd. surfactant (Emalex 710) 1 mass% aqueous solution 8.60 g
・ Ion-exchanged water 6.0g
・ Azinium salts (compound types listed in Table 1) Amounts listed in Table 1

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

2. Preparation of planographic printing plate precursors (12) to (15) Except that the image recording layer coating solution (1) is changed to the following image recording layer coating solution (2), it is the same as the preparation of the planographic printing plate precursor (1). Lithographic printing plate precursors (12) to (15) [for Examples 12 to 15] were obtained.

<Image recording layer coating solution (2)>
-Binder polymer (1) [above structure] 0.24 g
・ Infrared absorber (2) [the following structure] 0.05 g
・ Radical polymerization initiator (1) [above structure] 0.20 g
・ Polymerizable compound (Aronix M-215, manufactured by Toa Gosei Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound (sodium n-heptylsulfonate) 0.05 g
・ Grease sensitizer (benzyl-dimethyl-octylammonium / PF ₆ salt) 0.018 g
Sensitizing agent Ammonium group-containing polymer (Exemplified compound (23) of the present specification, reduced specific viscosity 44 cSt / g / ml) 0.035 g
・ Fluorosurfactant (1) [above structure] 0.005 g
・ Methyl ethyl ketone 18.0g

3. Preparation of lithographic printing plate precursor (16) The lithographic printing plate precursor (1) was used except that the protective layer coating solution (2) in which the inorganic layered compound dispersion (1) was not added in the protective layer coating solution (1) was used. A lithographic printing plate precursor (16) [for Example 16] was obtained in the same manner as in the production.

4). Preparation of lithographic printing plate precursor (18) A lithographic printing plate precursor (18) [for Comparative Example 2] was obtained in the same manner as the preparation of the lithographic printing plate precursor (17) except that the protective layer (2) was used.

5). Evaluation (exposure) of lithographic printing plate precursor
The resulting lithographic printing plate precursors (1) to (18) were subjected to the conditions of an external drum rotation speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi on a Fujixel-made Luxel PLASETTER T-6000III equipped with an infrared semiconductor laser. Exposed. The exposure image includes a solid image and a 50% dot chart of a 20 μm dot FM screen.

(Evaluation of ink fillability)
The obtained exposed original plate was attached to a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. Wet with the standard automatic printing start method of LITHRONE26 using dampening water of Ecology-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) and Epple Pantone Blau 072C (ink manufactured by Epple). After supplying water and ink and developing on the machine, printing was performed on Tokishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour. The number of printing paper sheets required until the ink density on the printing paper in the exposed area of the image recording layer reached a specified standard density was measured as ink fillability. The results are shown in Table 1.

(Evaluation of printing durability)
Printing was further continued after the evaluation of the ink deposition property described above. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. Printing durability was evaluated using the number of printed copies when the value measured by the Gretag densitometer for the 50% halftone dot area ratio of the FM screen in the printed material was 5% lower than the measured value for the 100th printed sheet. . The results are shown in Table 1.

(Evaluation of dirtiness)
The resulting lithographic printing plate precursor was image-exposed with a Trend setter 3244VX manufactured by Creo equipped with an infrared semiconductor laser under the conditions of an output of 6.4 W, an outer drum rotation speed of 150 rpm, and a resolution of 2400 dpi. The exposure image includes a solid image and a halftone gradation chart of a 20 μm dot FM screen. The exposed original plate is attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg, and dampening water [IF102 (etch solution manufactured by FUJIFILM Corporation) / water = 3/97 (volume ratio)] and TRANS-G (N). Using black ink (manufactured by Dainippon Ink & Chemicals, Inc.) and supplying dampening water and ink, 100 sheets were printed at a printing speed of 6000 sheets per hour.
Thereafter, the water scale of the printing press was narrowed down, and the amount of water supply was gradually reduced until tangling occurred in the net image. At this time, the degree of occurrence of entangled dirt was evaluated by the following index, and this was evaluated as dirtiness. The results are shown in Table 1.

A: Good entanglement and sufficient water / ink balance.
B: Slight entanglement occurs but is an acceptable level.
C: NG level in a state where entanglement occurred and the halftone shadow side was crushed.
D: Poor entanglement occurs just by squeezing a little water.

  As is apparent from Table 1, in the examples using the present invention, the inking property is improved without impairing the dirtiness and printing durability.

Claims (7)

  A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, wherein the protective layer contains an azinium salt. The lithographic printing plate precursor as claimed in claim 1, wherein the azinium salt is represented by the following general formula (I) or general formula (II).

In General Formula (I) and General Formula (II), R ¹ represents a monovalent organic group, and R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom or a halogen atom. Or a monovalent organic group. X ⁻ represents an anion. W represents a divalent organic linking group.   The lithographic printing plate precursor as claimed in claim 1, wherein the protective layer contains an inorganic stratiform compound.   The lithographic plate according to any one of claims 1 to 3, wherein the image recording layer contains (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound. A printing plate master.   The lithographic printing plate precursor as claimed in any one of claims 1 to 4, wherein the image recording layer comprises a hydrophobizing precursor.   6. The image recording layer according to claim 1, wherein the image recording layer is an image recording layer capable of forming an image by supplying printing ink and fountain solution on a printing machine after exposure to remove an unexposed portion. The lithographic printing plate precursor as described in any one of the above.   The lithographic printing plate precursor according to claim 6 is image-exposed and then mounted on a printing press or image-exposed after being mounted on a printing press, and printing ink and fountain solution are supplied to perform on-press development processing. A plate making method characterized by the above.