JP2008221610A - Original plate of lithographic printing plate and lithographic printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate of a lithographic printing plate which has a protective layer prevented from foaming on the occasion of coating, enables efficient formation of an image by laser exposure and shows excellent on-machine developability as well after an elapse of time, and to provide a lithographic printing method using it. <P>SOLUTION: The original plate of the lithographic printing plate has the protective layer containing latex of a polymer which is synthesized by polymerizing polymerizable monomers in all of which acrylonitrile accounts for 50 mass%, and which contains neither a surfactant nor a protective colloid. It is preferable that the average particle diameter of the polymer latex is 3 μm or less and that an image recording layer contains (A) a radical generator, (B) a sensitized coloring matter and (C) a compound having an ethylenic unsaturated bond enabling addition polymerization. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

In general, a lithographic printing plate comprises an oleophilic image area that receives ink 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). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer to be an image portion is left, and other unnecessary image recording layers are removed with an alkaline developer or an organic solvent. Plate making is performed by a method of exposing the surface of the hydrophilic support by dissolving and removing to obtain a lithographic printing plate.

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

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 (CTP) technology has been attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.
As described above, in recent years, simplification, drying, and no processing of plate making operations have become more desirable than ever in terms of both consideration for the global environment and adaptation to digitalization. It is coming.

As a lithographic printing plate precursor adapted to the above-mentioned demand, an lithographic printing plate precursor having an image forming layer (image recording layer) containing heat-meltable fine particles, a light and / or heat polymerizable image recording layer, and the like are used. In these lithographic printing plate precursors, a protective layer (overcoat layer) is provided on the image recording layer in order to impart oxygen barrier properties, prevent scratches in the image recording layer, and prevent ablation that occurs during high-illuminance laser exposure. Provided. Examples of the protective layer material include water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, cellulose polymers (eg, carboxymethyl cellulose), and examples in which mica is added thereto. . (For example, Patent Documents 1 to 3). However, when these materials are used, one or more of oxygen barrier properties, printing durability, initial inking properties, in-printing inking properties, developability, on-press developability, scratch resistance, etc. There was a problem that the performance deteriorated. In particular, when water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, and cellulose-based polymers that are suitably used as a protective layer and mica are added to these, some oxygen barrier properties are exhibited, but developability, In many cases, the inking property and the printing durability were simultaneously decreased. In addition, when the above hydrophilic polymer is used, the film becomes weak due to its hygroscopicity, the strength of the surface of the protective layer is insufficient, stickiness occurs, and the protective layer is scratched, resulting in a decrease in oxygen barrier properties. There are various problems such as adhesiveness when printing plates are stacked, and developability deteriorates with time, especially at high temperatures, and this improvement is one of the important technical issues. ing.
In addition, the present inventors have attempted to use a latex of a polymer to solve these problems, and found that the above-described various performances can be improved. Severely, the surface of the coating was disturbed, and the developability sometimes deteriorated under the aging conditions.

JP-A-9-160226 JP 2001-171250 A JP 2005-119273 A

  An object of the present invention is to provide a lithographic printing plate precursor that has a protective layer in which foaming during coating is prevented, can form an image efficiently by laser exposure, and exhibits excellent on-press developability even after aging, and It is to provide a planographic printing method using the same.

  As a result of intensive studies to achieve the above object, the present inventors have used a protective layer containing a polymer latex containing acrylonitrile as a repeating unit, polymerized in the absence of a surfactant and a protective colloid. The inventors have found that the above object can be achieved and completed the present invention.

That is, the present invention is as follows.
1. A lithographic plate characterized by having a protective layer containing a polymer latex synthesized by polymerizing a polymerizable monomer in which 50% by mass or more of the total polymerizable monomer is acrylonitrile in the absence of a surfactant and a protective colloid A printing plate master.
2. 2. The lithographic printing plate precursor as described in 1 above, wherein the polymer latex has an average particle size of 3 μm or less.
3. The image-recording layer comprising (A) a radical generator, (B) a sensitizing dye, and (C) a compound having at least one addition-polymerizable ethylenically unsaturated bond. The lithographic printing plate precursor as described in any one of the above.
4). 4. The lithographic printing plate precursor as described in 3 above, wherein the (B) sensitizing dye is an infrared absorber.
5. The lithographic printing plate precursor as described in any one of 3 to 4 above, wherein the image recording layer is removable with printing ink and / or fountain solution.
6). The lithographic printing plate precursor as described in any one of 3 to 5, wherein the image recording layer further comprises (D) a binder polymer.
7). The lithographic printing plate precursor as described in any one of 3 to 6, wherein the image recording layer further contains (E) a microcapsule or a microgel.
8). On the support, it has an image recording layer that can be recorded by infrared laser exposure, and after image recording by infrared laser, it is mounted on a printing machine without passing through a development processing step, or image recording by infrared laser after mounting the printing machine The lithographic printing plate precursor as described in any one of 3 to 7 above, wherein printing is possible.
9. The lithographic printing plate precursor as described in any one of 1 to 8 above, wherein the polymer latex is copolymerized with a bifunctional or higher polymerizable monomer.
10. The lithographic printing plate precursor as described in any one of 1 to 9 above, wherein the surfactant content of the coating solution for forming the protective layer is 0.2% by mass or less.
11. The step of exposing the lithographic printing plate precursor according to any one of 1 to 10 imagewise with an infrared laser, and an oil-based ink and a water-based ink without performing any development treatment on the exposed lithographic printing plate precursor A lithographic printing method comprising: a printing step of supplying a component and printing, and removing an infrared laser unexposed portion of the lithographic printing plate precursor image recording layer in the course of the printing step.

  According to the present invention, a lithographic printing plate precursor having a protective layer in which foaming at the time of coating is prevented, capable of forming an image efficiently by laser exposure, and exhibiting excellent on-press developability after aging, and A lithographic printing method using the same can be provided.

Hereinafter, the present invention will be described in detail.
[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the present invention comprises a polymer latex synthesized by polymerizing a polymerizable monomer in which 50% by mass or more of the total polymerizable monomer is acrylonitrile in the absence of a surfactant and a protective colloid. It has a layer.
Furthermore, the lithographic printing plate precursor according to the invention comprises an image recording layer containing (A) a radical generator, (B) an infrared absorber, and (C) a compound having at least one ethylenically unsaturated bond capable of addition polymerization. It is preferable that the image recording layer further contains (D) a binder polymer, (E) a microcapsule or a microgel.
Such an image recording layer can be recorded by infrared irradiation. In addition, after image recording by infrared exposure, printing can be performed in a printing process without passing through any wet development process step. It is a so-called on-machine developable image recording layer in which an unexposed image recording layer is removed by an oily component / hydrophilic component such as fountain solution.
Hereinafter, each element of the lithographic printing plate precursor according to the invention, such as a protective layer and an image recording layer, will be described in detail.

[Protective layer]
The protective layer of the present invention is formed by polymerizing a polymerizable monomer in which 50% by mass or more of all polymerizable monomers is acrylonitrile, and is coated with a latex of a polymer not containing a surfactant and a protective colloid. It is characterized by.
When this polymer latex that does not contain surfactants and protective colloids is used, it does not contain surfactants that are physically adsorbed on the latex particles, so that foaming during the coating of the protective layer is prevented. Since the adsorbed surfactant is not desorbed from the latex particles (because the functional group having a surface active action is chemically bonded to the latex particles), after the lithographic printing plate precursor has elapsed, particularly after high temperature aging However, excellent on-press developability can be maintained.

From the viewpoint of the printing durability and thickness of the lithographic printing plate precursor, it is important to prevent intermixing of the image recording layer and the protective layer when providing the protective layer. For this reason, in this invention, the polymer used for a protective layer is used as latex. Here, latex refers to a material in which a polymer substance is stably dispersed in an aqueous medium.
Further, from the viewpoint of promoting polymerization and increasing sensitivity, it is one of the preferred forms to improve oxygen barrier properties. In this aspect, a polymer containing acrylonitrile is used as a latex in this aspect.

  The glass transition temperature of the latex is preferably 20 ° C. or higher and 300 ° C. or lower, more preferably 30 ° C. or higher and 250 ° C. or lower, and particularly preferably 40 ° C. or higher and 230 ° C. or lower, from the viewpoints of stickiness prevention, scratch resistance improvement, and film formability during coating. preferable.

  The average particle size of the latex is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less from the viewpoint of dispersion stability.

  In the case where acrylonitrile is contained in the polymer, the acrylonitrile content is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and more preferably 80% by mass. It is particularly preferable to contain the above. If it is less than 50% by mass, the oxygen barrier property is greatly lowered, and good image formation cannot be obtained.

  The polymer latex of the present invention may contain other copolymerization components copolymerizable with acrylonitrile. Other copolymerization components that can be used in the present invention are not particularly limited as long as they can be copolymerized with acrylonitrile. Methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer as described in JP-B Nos. 54-25957, 59-53836 and 59-71048. , Monomers used in crotonic acid copolymer, (anhydrous) maleic acid copolymer, partially esterified maleic acid copolymer and partially amidated maleic acid copolymer, (meth) acrylates, (meth) acrylamide , Aromatic hydrocarbon rings having a vinyl group, heteroaromatic rings having a vinyl group, maleic anhydride, itaconic esters, crotonic acid Ester, (meth) acrylonitrile, crotonitrile, alpha-methyl crotonic nitrile, various styrenes, various benzoyloxy ethylenes, various acetoxy ethylene, vinyl carbazole, vinyl pyrrolidone, and the like.

  Among these, (meth) acrylic acid, optionally substituted alkyl having 1 to 25 carbon atoms or cycloalkyl (meth) acrylate, optionally having substituents having 6 to 25 carbon atoms. (Meth) acrylate having a ring, aralkyl (meth) acrylate having 7 to 25 carbon atoms which may have a substituent, aryl (meth) acrylate having 6 to 25 carbon atoms which may have a substituent,

(Meth) acrylamide, secondary or tertiary alkyl or cycloalkyl (meth) acrylamide having 1 to 25 carbon atoms which may have a substituent, and 6 to 25 carbon atoms optionally having a substituent (Meth) acrylamide having a secondary or tertiary bicyclo ring, optionally having a C 7-25 secondary or tertiary aralkyl (meth) acrylamide having a substituent, having a substituent A secondary or tertiary aryl (meth) acrylamide having 6 to 25 carbon atoms, (meth) acryloylmorpholine optionally having a substituent,

A substituted or unsubstituted aromatic hydrocarbon ring having 6 to 25 carbon atoms having a vinyl group, a substituted or unsubstituted heteroaromatic ring having 5 to 25 carbon atoms having a vinyl group, maleic anhydride, substituted or unsubstituted Styrene, α-methylstyrene, vinylimidazole, vinyltriazole, maleic anhydride, partially esterified maleic acid copolymer with substituted or unsubstituted alcohol having 1 to 25 carbon atoms, substituted or unsubstituted 1 to 25 carbon atoms Partially amidated maleic acid with amine, methyl jasmonate,

Itaconic acid, an alkyl or cycloalkyl ester having 1 to 25 carbon atoms which may have a substituent, an itaconic acid ester having a bicyclo ring having 6 to 25 carbon atoms which may have a substituent, substituted An itaconic acid aralkyl ester having 7 to 25 carbon atoms which may have a group, an itaconic acid aryl ester having 6 to 25 carbon atoms which may have a substituent,

Crotonic acid, C1-C25 alkyl crotonic acid or cycloalkyl ester which may have a substituent, Crotonic acid ester having a bicyclo ring having 6 to 25 carbons which may have a substituent, Substitution A crotonic acid aralkyl ester having 7 to 25 carbon atoms which may have a group, a crotonic acid aryl ester having 6 to 25 carbon atoms which may have a substituent,

Benzoyloxyethylenes optionally having substituents, acetoxyethylenes optionally having substituents, (meth) acrylonitrile, crotonnitrile, α-methylcrotonnitrile, optionally having substituents Vinylcarbazole and vinylpyrrolidone are preferred,

  Among them, (meth) acrylic acid, an optionally substituted alkyl having 1 to 20 carbon atoms or cycloalkyl (meth) acrylate, and optionally having a substituent having 6 to 20 carbon atoms. A (meth) acrylate having 7 to 20 carbon atoms, an aralkyl (meth) acrylate having 7 to 20 carbon atoms which may have a substituent, an aryl (meth) acrylate having 6 to 20 carbon atoms which may have a substituent,

(Meth) acrylamide, secondary or tertiary alkyl or cycloalkyl (meth) acrylamide having 1 to 20 carbon atoms which may have a substituent, and 6 to 20 carbon atoms optionally having a substituent (Meth) acrylamide having a secondary or tertiary bicyclo ring, optionally having a C 7-20 secondary or tertiary aralkyl (meth) acrylamide having a substituent, having a substituent Good secondary or tertiary aryl (meth) acrylamide having 6 to 20 carbon atoms, (meth) acryloylmorpholine optionally having a substituent,

A substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 carbon atoms having a vinyl group, a substituted or unsubstituted heteroaromatic ring having 5 to 20 carbon atoms having a vinyl group, maleic anhydride, substituted or unsubstituted Partially esterified maleic acid copolymers with alcohols having 1 to 20 carbon atoms, partially amidated maleic acids with substituted or unsubstituted amines having 1 to 20 carbon atoms, substituted or unsubstituted (α-methyl-) styrenes, Methyl jasmonate,

Itaconic acid, an alkyl or cycloalkyl ester having 1 to 20 carbon atoms which may have a substituent, an itaconic acid ester having a bicyclo ring having 6 to 20 carbon atoms which may have a substituent, substituted An aralkyl ester having 7 to 20 carbon atoms which may have a group, an aryl ester having 6 to 20 carbon atoms which may have a substituent,

Crotonic acid, C1-20 alkyl crotonic acid or cycloalkyl ester which may have a substituent, Crotonic acid ester having 6 to 20 carbon atoms which may have a substituent, substituted A crotonic acid aralkyl ester having 7 to 20 carbon atoms which may have a group, an aryl ester having 6 to 20 carbon atoms which may have a substituent,

Benzoyloxyethylenes optionally having substituents, acetoxyethylenes optionally having substituents, vinylcarbazole optionally having substituents, vinylpyrrolidone, (meth) acrylonitrile, crotonnitrile, α-methylcrotonnitrile is more preferred,

  In particular, (meth) acrylic acid, optionally substituted methyl (meth) acrylate, ethyl (meth) acrylate, linear or branched propyl (meth) acrylate, linear or branched butyl (meta ) Acrylate, linear or branched pentyl (meth) acrylate, normal hexyl (meth) acrylate, cyclohexyl (meth) acrylate, normal heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, normal octyl (meth) acrylate, normal Decyl (meth) acrylate, normal dodecyl (meth) acrylate,

Adamantyl (meth) acrylate optionally having a substituent, isobornyl (meth) acrylate, norbornanemethyl (meth) acrylate, norbornenemethyl (meth) acrylate, benzyl (meth) acrylate optionally having a substituent, Naphthylmethyl (meth) acrylate, anthracenemethyl (meth) acrylate, phenylethyl (meth) acrylate, optionally substituted phenyl (meth) acrylate, naphthyl (meth) acrylate,

(Meth) acrylamide, optionally substituted methyl or dimethyl (meth) acrylamide, ethyl or diethyl (meth) acrylamide, linear or branched propyl or dipropyl (meth) acrylamide, linear or branched butyl or Dibutyl (meth) acrylamide, linear or branched pentyl or dipentyl (meth) acrylamide, normal or dinormal hexyl (meth) acrylamide, cyclohexyl or dicyclohexyl (meth) acrylamide, 2-ethylhexyl or di (2-ethylhexyl) (meth) Acrylamide, optionally substituted adamantyl (meth) acrylamide, noradamantyl (meth) acrylamide, optionally substituted benzyl (meth) acrylate Luamide, naphthylethyl (meth) acrylamide, phenylethyl (meth) acrylamide, optionally substituted phenyl or diphenyl (meth) acrylamide, naphthyl (meth) acrylamide, (meth) acryloylmorpholine, piperidylacrylamide, pyrrolidyl Acrylamide,

Styrene, α-methyl styrene, vinyl pyridine, vinyl imidazole, vinyl triazole, maleic anhydride, methyl jasmonate, maleimide, N-substituted maleimide, itaconic acid, crotonic acid, optionally substituted methyl croto Nate, ethyl (crotonate, linear or branched propyl crotonate, linear or branched butyl crotonate, linear or branched pentyl crotonate, normal hexyl crotonate, cyclohexyl crotonate, normal heptyl crotonate, 2-ethylhexyl Crotonate, normal octyl crotonate, normal decyl crotonate, normal dedecyl crotonate, optionally substituted adamantyl crotonate, isobornyl crotonate, norbornane methyl crotonate , Norbornene methyl crotonate, optionally substituted benzyl crotonate, naphthyl methyl crotonate, anthracene methyl crotonate, phenyl ethyl crotonate, optionally substituted phenyl crotonate, naphthyl crotonate ,

Preferred are benzoyloxyethylene which may have a substituent, acetoxyethylene which may have a substituent, vinylcarbazole, vinylpyrrolidone, acrylonitrile and methacrylonitrile which may have a substituent.
The carboxyl group may be a metal salt.

Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an acyloxy having 1 to 20 carbon atoms. Group, an acyl group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 1 to 20 carbon atoms, an arylcarbonyl group having 6 to 20 carbon atoms, a dialkylamino group having 2 to 20 carbon atoms, and an alkylamino group having 1 to 20 carbon atoms , Halogen atom, cyano group, furyl group, furfuryl group, tetrahydrofuryl group, tetrahydrofurfuryl group, alkylthio group, trimethylsilyl group, trifluoromethyl group, carboxyl group, thienyl group, morpholino group, morpholinocarbonyl group, vinyl group,- OH group, -SO ₃ M group (M is, H, or Na, K), - COOM group (M is, H, or Na, K), (main ) Acryloyloxy group, a phenyl group, etc. are preferred,

Furthermore, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, an aralkyl group having 6 to 15 carbon atoms, an aryl group having 6 to 15 carbon atoms, an acyloxy group having 1 to 15 carbon atoms, a carbon number An acyl group having 1 to 15 carbon atoms, an alkoxycarbonyl group having 1 to 15 carbon atoms, an arylcarbonyl group having 6 to 15 carbon atoms, a dialkylamino group having 2 to 15 carbon atoms, an alkylamino group having 1 to 15 carbon atoms, a halogen atom, Cyano group, furyl group, furfuryl group, tetrahydrofuryl group, tetrahydrofurfuryl group, alkylthio group, trimethylsilyl group, trifluoromethyl group, carboxyl group, thienyl group, morpholino group, morpholinocarbonyl group, vinyl group, -OH group,- SO ₃ M group (M is, H, or Na, K), - COOM group (M is, H, or Na, K), (meth) acryloyl Oxy group, a phenyl group, etc. are preferred,

  In particular, methyl group, ethyl group, linear or branched propyl group, linear or branched butyl group, linear or branched pentyl group, normal hexyl group, cyclohexyl group, normal heptyl group, 2-ethylhexyl group, normal Octyl group, normal decyl group, normal dodecyl group, methyloxy group, ethyloxy group, linear or branched propyloxy group, linear or branched butyloxy group, linear or branched pentyloxy group, normal hexyloxy group, cyclohexyl Oxy group, normal heptyloxy group, 2-ethylhexyloxy group, normal octyloxy group, normal decyloxy group, normal dodecyloxy group, benzyl group, phenethyl group, naphthylmethyl group, naphthylethyl group, phenyl group, naphthyl group,

Methylcarbonyloxy group, ethylcarbonyloxy group, linear or branched propylcarbonyloxy group, linear or branched butylcarbonyloxy group, linear or branched pentylcarbonyloxy group, normal hexylcarbonyloxy group, cyclohexylcarbonyloxy group Normal heptylcarbonyloxy group, 2-ethylhexylcarbonyloxy group, normal octylcarbonyloxy group, normal decylcarbonyloxy group, normal dodecylcarbonyloxy group,

Methylcarbonyl group (acetyl group), ethylcarbonyl group, linear or branched propylcarbonyl group, linear or branched butylcarbonyl group, linear or branched pentylcarbonyl group, normal hexylcarbonyl group, cyclohexylcarbonyl group, normal heptyl Carbonyl group, 2-ethylhexylcarbonyl group, normal octylcarbonyl group, normaldecylcarbonyl group, normaldodecylcarbonyl group,

Methyloxycarbonyl group, ethyloxycarbonyl group, linear or branched propyloxycarbonyl group, linear or branched butyloxycarbonyl group, linear or branched pentyloxycarbonyl group, normal hexyloxycarbonyl group, cyclohexyloxycarbonyl group Normal heptyloxycarbonyl group, 2-ethylhexyloxycarbonyl group, normal octyloxycarbonyl group, normal decyloxycarbonyl group, normal dodecyloxycarbonyl group, benzoyl group, naphthylcarbonyl group,

Methyl or dimethylamino group, ethyl or diamino group, linear or branched propyl or dipropylamino group, linear or branched butyl or dibutylamino group, linear or branched pentyl or dipentylamino group, normal hexyl or dinorma Ruhexylamino group, cyclohexyl or dicyclohexylamino group, normal heptyl or dinormalheptylamino group, 2-ethylhexyl or di (2-ethylhexyl) amino group,

Fluorine atom, chlorine atom, bromine atom, cyano group, furyl group, furfuryl group, tetrahydrofuryl group, tetrahydrofurfuryl group, alkylthio group, trimethylsilyl group, trifluoromethyl group, carboxyl group, thienyl group, morpholino group, morpholinocarbonyl group , Vinyl group, —OH group, —SO ₃ M group (M is H or Na, K), —COOM group (M is H or Na, K), (meth) acryloyloxy group, phenyl group, etc. preferable.

  Further, these substituents may be further substituted with the above substituents.

Other copolymerizable monomers include phosphoric acid, phosphoric acid esters, quaternary ammonium salts, ethyleneoxy chains, propyleneoxy chains, sulfonic acids and their salts, hydrophilic monomers containing morpholinoethyl groups, and the like. It is useful for imparting dispersion stability.
Among the hydrophilic polymerizable monomers copolymerized with the above acrylonitrile, in particular, a polymerizable monomer having at least one acidic group selected from the group consisting of a sulfonic acid group, a sulfuric acid group, a carboxyl group, and a salt thereof. Useful. Specific examples include vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, p-styrene sulfonic acid, methacrylic acid sulfoethyl ester, methacrylic acid sulfopropyl ester, acrylic acid sulfoethyl ester, acrylic acid sulfopropyl ester, 2- Acrylamide-2-methyl-1-propanesulfonic acid, acrylic acid, methacrylic acid and their salts (alkali metal salts (Na, K, Li, etc.), ammonium salts (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetra Butylammonium, etc.), etc.).
These polymerizable monomers having an acidic group may be used alone or in combination of two or more.
The polymerizable monomer having an acidic group is preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 35% by mass or less in the whole monomer.

In the present invention, it is preferable to use a polyfunctional polymerizable monomer as the polymerizable monomer. First, from the viewpoint of improving the dispersion stability of the synthesized latex, it is preferable to form a ternary polymer latex using a polyfunctional monomer. Secondly, in the step of developing the exposed printing plate, it is preferable to form a ternary polymer latex using a polyfunctional monomer with regard to developability after change with time (corresponding to conditions after dry thermo). . The reason why the development property after the dry thermo is improved by the ternary polymer latex (crosslinked particles) is considered to be because the fusion of the latex particles contained in the protective layer with time is suppressed.
The polyfunctional polymerizable monomer is not particularly limited as long as it is a monomer having two or more polymerizable groups in the molecule.
Examples of multifunctional polymerizable monomers include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, glycerol dimethacrylate, glycerol diacrylate, 1,6-hexanediol dimethacrylate, divinylbenzene, penta Examples include erythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, and the like.
These polyfunctional polymerizable monomers are preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 35% by mass or less, based on the total amount of polymerizable monomers.

  Although the number of types of monomers to be copolymerized is not particularly limited, 1 to 12 types are preferable, 1 to 8 types are more preferable, and 1 to 5 types are particularly preferable.

  The content of the polymer latex of the present invention in the protective layer is preferably 5% by mass or more, more preferably 10% by mass or more, and most preferably 15% by mass or more based on the solid content of the protective layer. Within this range, good oxygen barrier properties and inking properties can be obtained.

  In the protective layer of the present invention, other polymers can be used in combination as long as they do not interfere with the function of the polymer latex. As the polymer that can be used in combination, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected. 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, polymethacrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide and cellophane. These may be used in combination of two or more as required.

  A relatively useful material among the above materials includes water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol that can be used in the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of an unsubstituted vinyl alcohol unit having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester 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, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA124H, PVA-CS, PVA-CST, PVA-HC, PVA- 203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, L-8 etc. are mentioned. Examples of the modified polyvinyl alcohol include KL-318, KL-118, KM-618, KM-118, SK-5102 having an anion-modified site, C-318, C-118 and CM-318 having a cation-modified site. M-205 and M-115 having terminal thiol modification sites, MP-103, MP-203, MP-102, MP-202 having terminal sulfide modification sites, and ester modification sites with higher fatty acids HL-12E, HL-1203, and other reactive silane-modified R-1130, R-2105, R-2130, and the like.

The protective layer may contain a layered compound as long as it does not interfere with the function of the polymer latex. The layered compound is a particle having a thin plate-like shape. For example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any of Li, K, Na, Ca, Mg, organic cation, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, V, and D is Si or Al. 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.H2O.

Examples of natural mica used in the protective layer include muscovite, soda mica, phlogopite, biotite, and sericite. In addition, examples of the synthetic mica include 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 / 5Li 1/8 (Si 4} O 10) swelling mica _{F 2.} Synthetic smectite is also useful.

Among the above layered compounds, fluorine-based swellable mica which is a synthetic layered compound is particularly useful from the viewpoint of availability and uniformity. 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 Significantly greater than viscous minerals. As a result, the lattice layer is deficient in positive charge, and in order to compensate for this, positive charges of organic cations such as Li +, Na +, Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are provided between the layers. Ions are adsorbed. 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 swelling synthetic mica have this tendency.

As the shape of the layered compound, from the viewpoint of diffusion control, the thinner the better, the better the plane size as long as the smoothness of the coated surface and the transmittance of actinic rays are not impaired. Therefore, 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.
The average particle diameter of the layered compound is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the suppression of permeation of oxygen and moisture is insufficient and the effect cannot be exhibited sufficiently. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among the 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 the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture 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.

  When the layered compound is used for the protective layer, it is used as a dispersion. A general method for dispersing a layered compound will be described using examples. First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen, and then dispersed using a disperser. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 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 protective layer coating solution using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a polymer latex.

  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 polymer used for a protective layer. Even when a plurality of types of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added to the polymer latex of the present invention in an amount corresponding to several mass% to give flexibility, and sodium alkyl sulfate, alkyl sulfone can be added. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers can be added. The addition amount of these activators can be added 0.001-100 mass% with respect to the polymer latex liquid of this invention.
As addition amount, 0.001-0.30 mass% is preferable with respect to polymer latex liquid, 0.001-0.25 mass% is more preferable, 0.001-0.20 mass% is especially preferable.

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

  Furthermore, other functions can be imparted to the protective layer. For example, 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.

This protective layer coating solution includes known anionic surfactants, nonionic surfactants, cationic surfactants, fluorosurfactants and water-soluble plasticizers for improving the physical properties of coatings. Additives can be added. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion with the image recording layer and the temporal stability of the coating solution may be added to the coating solution.
As addition amount, 0.001-0.30 mass% is preferable with respect to a protective layer coating liquid, 0.001-0.25 mass% is more preferable, 0.001-0.20 mass% is especially preferable.

The protective layer coating solution thus prepared is applied onto the image recording layer provided on the support and dried to form the protective layer. The coating solvent can be appropriately selected, but when the polymer latex of the present invention is used, it is preferable to use purified water such as distilled water or ion exchange 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. . Specific examples of the protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.
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. in the range of 02~1g / ^{m 2.}

(Image recording layer)
<(A) Radical generator>
Although it does not specifically limit as (A) radical generator of this invention, The compound represented with the following general formula (I) can be used conveniently.

In general formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom, a halogen atom, or a monovalent substituent. X- represents an anion.
Examples of the monovalent substituent include, for example, a halogen atom, amino group, substituted amino group, substituted carbonyl tomb, hydroxyl group, substituted oxy group, thiol group, thioether group, silyl group, nitro group, cyano group, alkyl group, alkenyl. Group, aryl group, heterocyclic group, sulfo group, substituted sulfonyl group, sulfonate group, substituted sulfinyl group, phosphono group, substituted phosphono group, phosphonato group, substituted phosphonato group, etc. It may have a group.

As the general formula (I) compound represented by the general formula framework of specific structure in the compound represented by (I) (cation portion) is bonded through the R ^1, in the cationic portion molecules Two or more compounds (multimeric forms) are also included, and such compounds are also preferably used.

Furthermore, the compound represented by general formula (I) may be a compound (polymer type) introduced into the polymer side chain via any of R ^{1 to} R ⁶ , and is mentioned as a preferred embodiment.

  Specific examples of the compound represented by the general formula (I) [Exemplary Compounds A-1 to A-34] are listed below, but the scope of the present invention is not limited thereto.

Only 1 type may be used for the compound represented by the said general formula (I), and 2 or more types may be used together. In that case, the monomer type, the multimer type, and the polymer type can be used in combination with different types of compounds.
As content of the compound represented by general formula (I) in this invention, 0.1-50 mass% is preferable in the image recording layer total solid of a lithographic printing plate precursor, More preferably, it is 0.5- It is 30 mass%, More preferably, it is 5-20 mass%.
When the content is within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained. Moreover, the compound represented by general formula (I) may be added to the same layer as other components, or another layer may be provided and added thereto.

  As the radical generator (A) of the present invention, other radical generators other than the compound represented by the general formula (I) can be used. In addition, at least one compound of the general formula (I) and at least one other radical generator can be used in combination.

  Other radical generators used in the present invention are compounds that generate radicals by light, heat, or both energies to initiate and accelerate the polymerization of a compound having a polymerizable unsaturated group, and are known in the art. Examples thereof include a thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, and a photopolymerization initiator. The radical generator suitably used in the present invention refers to a compound that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating a radical by thermal energy. As the thermal radical generator according to the present invention, a known polymerization initiator, a compound having a bond with small bond dissociation energy, or the like can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.

Other radical generators include, for example, (a) organic halides, (b) carbonyl compounds, (c) organic peroxides, (d) azo polymerization initiators, (e) azide compounds, (f) metallocenes Compounds, (g) hexaarylbiimidazole compounds, (h) organic borate compounds, (i) disulfone compounds, (j) oxime ester compounds, (k) onium salt compounds, and the like.
Hereinafter, each compound will be described.

  (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. Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”, and the oxazole compound and s-triazine compound substituted with a trihalomethyl group.

  More preferably, an s-triazine derivative having at least one mono, di, or trihalogen-substituted methyl group bonded to the s-triazine ring, 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, -(3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [1 -(P-methoxyphenyl) -2,4-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 (trichloromethyl) -s-triazine, 2- (p -Tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-natoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-pheni Thio-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 and the like.

  (B) Examples of carbonyl compounds include benzophenone, Michler's 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) 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 peroxide Carbonate, dimethoxyisopropylperoxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butylperoxyacetate, tert-butylperoxypivalate, tert-butylperoxyneodecanoate, tert -Butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ', 4,4'-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3', 4 4′-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate ), Carbonyldi (t-hexylperoxydihydrogen diphthalate), and the like.

(D) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.
(F) As the metallocene compound, 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, such as 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 Examples include 4,5,6-pentafluorophen-1-yl, iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109, and the like.

  (G) Examples of hexaarylbiimidazole compounds include, for example, JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Various compounds described in the publication, 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'-tetra (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5,5 '-Tetraphenylbiimi Sol, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5 Examples include 5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like.

(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-A-2000-131837, JP-A-2002-107916, Japanese Patent No. 2764769, JP-A-2002-116539, etc., and Kunz, Martin “Rad Tech'98. Proceeding April 19-22, 1998, Chicago Organoboron salts or organic boron oxosulfonium complexes described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, JP-A-6-175554, JP-A-6-175553 The organoboron iodonium complex described in JP-A-9-188710, the organoboron phosphonium complex described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-5-140589 Specific examples include organoboron transition metal coordination complexes such as 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) P1653-1660), J. MoI. C. S. Perkin II (1979) P156-162, Journal of Photopolymer Science and Technology (1995) P202-232, compounds described in JP-A 2000-66385, compounds described in JP-A 2000-80068, specifically described below Compound etc. are mentioned.

(K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Bal et al, Polymer, 21, 423 (1980), diazonium salts, US Pat. No. 4,069,055, ammonium salts described in JP-A-4-365049, US Pat. No. 4,069, No. 055, No. 4,069,056, phosphonium salts described in European Patent Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201; -150848, JP-A-2-296514, European Patent Nos. 370,693, 390,214, 233,567, 297,443, 297,442, USA Patent Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,734,444 , 2,833,827, German Patent 2,904,626, the 3,604,580 Patent, sulfonium salts described in the specification of Nos. 3,604,581,
J. et al. 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, from the viewpoint of reactivity and stability, the oxime ester compound or the diazonium salt, iodonium salt, and sulfonium salt described in detail below are preferable. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (RI-I) to (RI-III).

In 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 alkyl groups 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 an 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, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the surface, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, and sulfinate ion are preferable.

In 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. Alkyl group, alkenyl group having 1 to 12 carbon atoms, alkynyl group having 1 to 12 carbon atoms, aryl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, aryloxy group having 1 to 12 carbon atoms, halogen atom , C 1-12 alkylamino group, C 1-12 dialkylamino group, C 1-12 alkylamide group or arylamide group, carbonyl group, carboxyl group, cyano group, sulfonyl group, carbon number 1 -12 thioalkyl group and C1-C12 thioaryl group are mentioned. Z ^21- represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the viewpoint of reactivity, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable.

In 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 halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the viewpoint of reactivity, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable. More preferred are the carboxylate ions described in JP-A No. 2001-343742, and particularly preferred are the carboxylate ions described in JP-A No. 2002-148790.
Examples of onium salts that can be suitably used as radical generators in the present invention will be given below, but the present invention is not limited thereto.

From the viewpoint of improving visibility among these other radical generator, a onium salts, inorganic anions as counter ions, ^e.g., PF6 @ -, BF4 @ ^-, and C4F9SO3 ^- preferably has the like, further, color Therefore, diaryl iodonium salts having two or more electron donating groups are preferable. This radical generator is a compound having a diaryliodonium skeleton, and this aryl group is a compound having 2 or more, preferably 3 or more electron donating groups such as an alkyl group and an alkoxy group. The electron donating group is preferably introduced at the para-position and ortho-position of the aryl group of the iodonium salt.

These other radical generators may be used alone or in combination of two or more. Moreover, these radical generators may be added to the same layer as other components, or another layer may be provided and added thereto.
The total content of the radical generator in the present invention is preferably from 0.1 to 50% by mass, more preferably from 0.5 to 30% by mass, and more preferably from 1 to 20% by mass with respect to the total solid content constituting the image recording layer. Most preferred is a ratio.

<(B) Sensitizing dye>
The image recording layer of the present invention preferably uses a sensitizing dye corresponding to each light source in order to improve compatibility with a light source such as an infrared laser, visible light, or ultraviolet laser.

(1) In the case of an infrared laser When the lithographic printing plate precursor of the present invention is image-formed with a light source that emits an infrared ray of 760 to 1200 nm, it is usually essential to use an infrared absorber. The infrared absorber has a function of converting absorbed infrared rays into heat and a function of being excited by infrared rays and transferring electrons / energy to a radical generator containing the compound of the general formula (I). 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, and an infrared absorbing dye is preferable from the viewpoint of effects.

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 JP-A-58-181690 and JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-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.

In addition, 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 suitable. ) 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 preferable example of the dye includes near infrared absorbing dyes described as the formulas (I) and (II) in US Pat. No. 4,756,993.
Other preferable examples of the infrared absorbing dye of the present invention include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. From the viewpoint of color change due to electron transfer, a 5-membered ring in the molecule, In particular, those having a 5-membered heterocycle containing a nitrogen atom are preferred. Further, cyanine dyes and indolenine cyanine dyes are preferred, and one particularly preferred example is a cyanine dye represented by the following general formula (i).

In general formula (i), X ¹ represents a hydrogen atom, a halogen atom, —N (Aryl) ₂ , X ² -L ¹ or a group represented by the structural formula below. Here, Aryl represents an aryl group which may have a substituent, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, a hetero atom. The aromatic ring which has and the C1-C12 hydrocarbon group containing a hetero atom are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.
Wherein, X _a below ^- Z _a is described below ^- has the same definition as substitution R ^a is a hydrogen atom, an alkyl group, an aryl group, selected substituted or unsubstituted amino group, and a halogen atom Represents a group.

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

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. 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 halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, from the storage stability of the recording layer coating solution. Tetrafluoroborate ion, hexafluorophosphate ion, and aryl sulfonate ion.
In view of improving visibility, _{Z a} ^- is preferably an inorganic anion or a counter anion of a strong acid, from this point of _{^{view, PF 6 -, BF 4 -}} , CF 3 SO 3 -, C 4 F ₉ SO ₃ ^— can be mentioned, and PF ₆ ^— is most preferable among them.

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

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

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

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

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

  As a method for dispersing the pigment, a known dispersion technique used 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).

  Among the above infrared absorbers, particularly preferable infrared absorbers for the lithographic printing plate precursor according to the invention include compounds having at least one solvent-soluble group on the skeleton of the cyanine dye. The solvent-soluble group in the present invention refers to an organic functional group that can improve the solvent solubility of the infrared absorber, and is not particularly limited as long as it is a functional group having such a function. Oxy group, aryloxy group, alkylcarbonyl group, arylcarbonyl group, alkyloxycarbonyl group, aryloxycarbonyl group, sulfonylamide group, carboxyl group, sulfonyl acid group, hydroxy group, alkylcarbonyloxy group, arylcarbonyloxy group, and And an amide group. Among these, more preferable solvent-soluble groups include an alkyloxy group, an aryloxy group, an alkyloxycarbonyl group, and an aryloxycarbonyl group. The most preferred solvent-soluble groups include alkyloxy groups and aryloxy groups.

More specifically, those having a cyanine dye structure represented by the general formula (i) and having at least one solvent-soluble group in the molecule are preferable. Any of the cyanine dye structures represented by the general formula (i), preferably an aromatic hydrocarbon group represented by Ar ¹ or Ar ² , nitrogen atoms at both ends, and X ¹ represents —N (Aryl) ₂ More preferably, a solvent-soluble group is introduced into the aromatic ring or the like. From the viewpoint of improving the on-press developability, it is most preferable to introduce a solvent-soluble group on the nitrogen atoms at both ends. Although the number of solvent-soluble groups to be introduced is at least one, the image recording layer can be applied evenly in a high concentration state, and the residue during on-press development due to the components in the image recording layer can be applied. From the standpoint of suppressing the generation of the color and improving the on-press developability, it is preferable that 2 to 6 are introduced on one molecule of the cyanine dye.

  Specific examples of the infrared absorbent that can be suitably used in the present invention include, but are not limited to, the following.

The infrared absorber may be added to the same layer as other components, or may be added to another layer, but when the negative planographic printing plate precursor is prepared, the image recording layer It adds so that the light absorbency in the maximum absorption wavelength in the wavelength range of 760 nm-1200 nm may be in the range of 0.3-1.2 by the reflection measurement method. Preferably, it is the range of 0.4-1.1. Within this range, a uniform polymerization reaction in the depth direction of the image recording layer proceeds, 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. 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 precursor is formed, and the reflection density is optically measured. Examples thereof include a method of measuring with a densitometer, a method of measuring with a spectrophotometer by a reflection method using an integrating sphere, and the like.

  The addition amount of the infrared absorber to the image recording layer is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and more preferably 1 to 10% by mass in the total solid content. % Addition is more preferable.

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

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

  The content of the sensitizing dye compatible with visible light or ultraviolet laser is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.5 to 30% by mass, based on the total solid content constituting the image recording layer. Preferably it is 1-20 mass%.

<(C) Compound having at least one ethylenically unsaturated bond capable of addition polymerization>
The image recording layer of the present invention contains (C) a compound having at least one addition-polymerizable ethylenically unsaturated bond (hereinafter, appropriately referred to as a polymerizable compound) in order to perform an efficient curing reaction. Is preferred.
The polymerizable compound in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one terminal ethylenically unsaturated bond, preferably two or more. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, an amino group or a mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and a monofunctional or polyfunctional compound. A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

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

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

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate Sorbitol tetritaconate, etc. 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.

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

^{_{CH 2 = C (R 4)}} COOCH 2 CH (R 5) OH (ii)
(However, R ⁴ and R ⁵ represent H or CH _3. )

  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, and 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 gazette, 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), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic 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 unsaturated groups (for example, acrylic ester, methacrylic ester, styrenic compound, A method of adjusting both sensitivity and strength by using a vinyl ether compound) is also effective.
In addition, the selection and use method of the addition polymerization compound is an important factor for compatibility with other components in the image recording layer (for example, binder polymer, radical generator, colorant, etc.) and dispersibility. 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 substrate and the protective layer described later.

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

<(D) Binder polymer>
In the image recording layer according to the present invention, a binder polymer can be further used as necessary for the purpose of improving the film properties of the image recording layer to be formed.
As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and a linear organic polymer having a film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

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

Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, where the ester or amide residue (-COOR or CONHR R) is ethylene. Examples thereof include polymers having a polymerizable 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, or an alkyl group having 1 to 20 carbon atoms, an aryl group, and an alkoxy group. R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue. Represents a group).

Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-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.

  The binder polymer having crosslinkability, for example, has a free radical (polymerization initiation radical or a growth radical in the polymerization process of the polymerizable compound) added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is formed directly between the 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 together, thereby causing cross-linking between polymer molecules. Forms and cures.

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

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

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

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

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

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

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

(D) Content of binder polymer is 0-90 mass% with respect to the total solid of an image recording layer, It is preferable that it is 0-80 mass%, and it is more preferably 0-70 mass%. preferable. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use (C) polymeric compound and (D) binder polymer in the quantity used as 0.5 / 1-4/1 by mass ratio.

  In the image recording layer of the lithographic printing plate precursor according to the present invention, in addition to the above components (A) to (C) and further each component such as (D) a binder polymer used as desired, the effects of the present invention are not impaired. Depending on the purpose, various compounds can be contained.

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

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

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

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

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

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

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

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

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

<Bakeout agent>
In the image recording layer of the present invention, a compound that changes color by an acid or a radical can be added to produce a printout image.
In the present invention, an image having excellent plate inspection properties is formed in the exposed region by the synergistic effect of the radical generator (A) and the infrared absorber (B). Although not necessary, it can be used in combination for the purpose of improving plate inspection.
Examples of compounds that can be used for this purpose include various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine.

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

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

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

<Polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer, a small amount of a thermal polymerization inhibitor is preferably added to the image recording layer of the present invention.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t- (Butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

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

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

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

<Low molecular hydrophilic compound>
The image recording layer of the present invention may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of hydrophilic low-molecular compounds 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, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

<(E) Microcapsule / Microgel>
In the present invention, several modes can be used as a method of incorporating the above-mentioned image recording layer constituent components (A) to (C) and the above-mentioned other constituent components into the image recording layer. One is a molecular dispersion type image recording layer in which the constituent components are dissolved and applied in an appropriate solvent as described in, for example, JP-A-2002-287334. In another embodiment, for example, as described in JP-A-2001-277740 and JP-A-2001-277742, all or part of the constituent components are encapsulated in microcapsules and contained in the image recording layer. It is a microcapsule type image recording layer. Further, in the microcapsule type image recording layer, the constituent component can be contained outside the microcapsule. Here, it is preferable that the microcapsule-type image recording layer includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule. As another embodiment, an embodiment in which the image recording layer contains crosslinked resin particles, that is, microgel, can be mentioned. The microgel may contain a part of the constituent component in and / or on the surface thereof. In particular, an embodiment in which a reactive microgel is formed by having a polymerizable compound on the surface is particularly preferable from the viewpoint of image forming sensitivity and printing durability.
In order to obtain better on-press developability, the image recording layer is preferably a microcapsule type or microgel type image recording layer.

As a method for microencapsulating or microgelling the image recording layer constituent components, known methods can be applied.
For example, as a method for producing microcapsules, 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, The method by the interfacial polymerization method found in US Pat. No. 42-446, the method by the precipitation of polymer found in US Pat. Nos. 3,418,250 and 3,660,304, the isocyanate found in US Pat. No. 3,796,669 Method using polyol wall material, method using isocyanate wall material found in US Pat. No. 3,914,511, urea found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802 -Formaldehyde or urea formaldehyde A method using a resorcinol-based wall forming material, a method using a wall material such as melamine-formaldehyde resin, hydroxycellulose, etc. found 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 seen in British Patent Nos. 952807 and 967074 There are laws, but it is not limited to these.

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

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, non-patent document as described in JP-A-5-61214, and the like. Granulation by aqueous dispersion polymerization can be used. However, it is not limited to these methods.
As the method using the interfacial polymerization, the known microcapsule production method described above 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 still more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

<Phosphonium compound>
A phosphonium compound may be added to the image recording layer and / or the protective layer in order to improve the inking property. The phosphonium compound is preferably a phosphonium compound represented by the following general formula (iii) or (iv). Especially, the phosphonium compound represented by general formula (iii) is preferable.

In formula (iii), Ar _{1 to} Ar ₆ each independently represents an aryl group or a heterocyclic group, L represents a divalent linking group, X represents an n-valent counter anion, and n represents 1 to 1 3 represents an integer, and m represents a number satisfying n × m = 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.

X ⁻ represents a counter anion, and preferred examples include halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, carboxylate anions, sulfate anions, PF 6 ⁻ , BF 4 ⁻ and perchlorate anions. Can be mentioned. Of these, halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, and carboxylate anions are particularly preferable.

  Specific examples of the phosphonium salt represented by the general formula (iii) used in the present invention are shown below.

In the general formula (iv), R _{1 to} R ₄ are each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aryloxy group, which may have a substituent, Represents an alkylthio 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.
Here, when R _{1 to} R ₄ are an alkyl group, an alkoxy group or an alkylthio group, the carbon number is usually 1 to 20, and when the R _{1 to} R ₄ is an alkenyl group or an alkynyl group, the carbon number is usually 2 to 15 and a cycloalkyl group. In some cases, the number of carbon atoms is usually 3 to 8, the aryl group is a phenyl group, a naphthyl group, etc., the aryloxy group is a phenoxy group, a naphthyloxy group, etc., the arylthio group is a phenylthio group, etc. Examples of the group include a furyl group and a thienyl group. Examples of the substituent that may be present include an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group, an alkylthio group, an aryl group, an aryloxy group, and an arylthio group. Group, sulfino group, sulfo group, phosphino group, phosphoryl group, amino group, nitro group, cyano group, hydroxy group, halogen atom and the like. These substituents may further have a substituent.
Examples of the anion represented by X ⁻ include halide ions such as Cl ⁻ , Br ⁻ and I ⁻ , inorganic acid anions such as ClO ₄ ⁻ , PF ₆ ⁻ and SO ₄ ⁻² , organic carboxylate anions and organic sulfonate anions. Can be mentioned. Examples of the organic group of the organic carboxylate anion and organic sulfonate anion include methyl, ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl, fluorophenyl, difluorophenyl, pentafluorophenyl, thienyl, pyrrolyl and the like. Among these, Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , PF ₆ ^{— and the} like are preferable. Specific examples of phosphonium compounds suitable for the present invention are shown below.

  The addition amount of the phosphonium salt to the image recording layer or the protective layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass in the solid content of each layer, and 0.1 to 5% by mass. Most preferred. Within these ranges, good ink fillability can be obtained.

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

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

[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. A preferable support includes 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, and even more preferably from 0.2 to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform a 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 roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

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

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

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. 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.

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

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.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
Examples of the back coat layer include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organic metal compounds or inorganic metal compounds described in JP-A-6-35174, and the like. 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 is inexpensive. It is preferable in that it is easily available.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the image recording layer and the support, if necessary, particularly in the case of an on-press development type lithographic printing plate precursor. Since the undercoat layer tends to cause the image recording layer to peel off from the support in the unexposed area, the on-press developability is improved. In addition, in the case of infrared laser exposure, since the undercoat layer functions as a heat insulating layer, the heat generated by the exposure does not diffuse to the support and can be used efficiently, so that the sensitivity can be increased. There is.
Specific examples of the undercoat layer compound (undercoat compound) include silane coupling agents having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, Preferable examples include phosphorus compounds having an ethylenic double bond reactive group described in Kaihei 2-304441.
The most preferred undercoat compound includes a polymer resin obtained by copolymerizing a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

An essential component of the undercoat polymer resin is an adsorptive group on the surface of the hydrophilic support. The presence or absence of adsorptivity on 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, the support on which the test compound is applied is sufficiently washed with an easily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the amount of adsorption of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. The compound having support adsorptivity is a compound that remains at 1 mg / m ² or more even after the above-described washing treatment.

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

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

In the above formula, 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, and preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferred is a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom. Z is a functional group that adsorbs to the surface of the hydrophilic support.
In the formula (v), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom. In the formula (v), L is a divalent linking group. L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group) or divalent A heterocyclic group, or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, R is an aliphatic group, an aromatic group; Or a heterocyclic group) or a combination with carbonyl (—CO—).

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

L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).
In the formula (vi), 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. L represents the same divalent linking group or single bond as in formula (v).

The adsorptive functional group is as described above.
Examples of typical compounds represented by formula (v) or (vi) are shown below.

Examples of the hydrophilic group of the undercoat polymer resin that can be used in the present invention include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, a hydroxypropyl group, a polyoxypropyl group, and an amino group. Preferred examples include a group, aminoethyl group, aminopropyl group, ammonium group, amide group, carboxymethyl group, sulfonic acid group, and phosphoric acid group. Among these, a monomer having a sulfonic acid group exhibiting high hydrophilicity is preferable. Specific examples of the monomer having a sulfonic acid group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, 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. Of these, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferred in view of hydrophilic performance and handling of synthesis.

  The polymer resin for the undercoat layer of 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.

  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 (-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) in 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 include —CH ₂ CH═CH ₂ (described in JP-B-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 molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1000 or more, preferably 2000 to 25 More preferably, it is 10,000. The polydispersity (mass average molecular weight / number average molecular weight) 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, etc., but is preferably a random polymer.

The undercoat polymer resin may be used alone or in combination of two or more. The undercoat layer coating solution is obtained by dissolving the above-described undercoat polymer 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.}

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

[Printing method]
In the lithographic printing method of the present invention, as described above, after exposing the lithographic printing plate precursor of the present invention imagewise with an infrared laser, an oil-based ink and an aqueous component are supplied without any development processing steps. Print.
Specifically, after exposing the lithographic printing plate precursor with an infrared laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on the printing machine, Examples include a method of printing with an infrared laser and printing without going through a development process.

After the lithographic printing plate precursor is exposed imagewise with a laser, the aqueous component and the oil-based ink are supplied and printed without going through a development process such as a wet development process. The image recording layer cured by the above process forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in the portion.
As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, the water-based component or oil-based ink may be first supplied to the plate surface, but the oil-based ink is first used in order to prevent the water-based component from being contaminated by the image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and the oil-based ink, a normal fountain solution 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.

1. Examples of polymer latex synthesis Examples of polymer latex are shown below, but the polymer latex used in the present invention is not limited thereto.

[Synthesis Example 1]
To a 200 ml three-necked flask equipped with a mechanical stirrer, 118 g of water, 4.8 g of acrylonitrile, 0.2 g of methacryloyloxyethyl sulfonic acid sodium salt (sulfoethyl methacrylate Na salt: SEM) and 1.19 g of divinylbenzene were added. Next, the inside of the system was purged with nitrogen, followed by nitrogen flow (flow rate: 10 ml / min). Next, after heating up to 70 degreeC, potassium persulfate (KPS: 0.27g) was added, stirring at the rotational speed of 300 rpm. After the addition, the mixture was stirred at 70 ° C. for 3 hours. Subsequently, the temperature was raised to 95 ° C., and the amount of nitrogen flow was set at a flow rate = 100 ml / min, followed by stirring for 2 hours. Distilled acrylonitrile was captured by a Dean-Stark tube equipped with a cooling tube.
Table 1 shows the solid content, the amount of aggregates generated during polymerization, the stability of the latex, the particle size, and the amount of residual monomers.
As shown in Table 1, a polymer latex containing acrylonitrile at a high content, no residual monomer, and high dispersion stability was obtained by using a simple production apparatus.

[Synthesis Examples 2 to 6]
Emulsion polymerization was carried out in the same manner as in Example 1 except that the type, amount, and initiator type of the copolymerization monomer were changed as shown in Table 1. The results are shown in Table 1.

[Comparative Synthesis Example 1]
To a 200 ml three-neck flask equipped with a mechanical stirrer, 85 g of water, 0.3 g of SDS (sodium dodecyl sulfate), and 5 g of acrylonitrile were added. Subsequently, the inside of the system was flowed with nitrogen (flow rate: 10 ml / min.) And heated to 70 ° C. An aqueous solution (10 ml) of KPS (potassium persulfate) 0.27 g was added at 70 ° C. over 2 hours, and after completion of the KPS addition, the mixture was further stirred at 70 ° C. for 1 hour to obtain a latex (solid content = 4.16). % By mass: average particle diameter = 0.165 μm (laser scattering method)).

[Comparative Synthesis Example-2]
A latex was obtained in the same manner as Comparative Synthesis Example 1 except that the polymerization monomer was changed to 4.5 g of acrylonitrile and 0.5 g of divinylbenzene (solid content = 4.46% by mass: average particle size = 0.130 μm ( Laser scattering method)).

2. Preparation of planographic printing plate precursor [Example 1]
(1) Production of support After degreasing treatment at 50 ° C. for 30 seconds using a 10% by mass aqueous sodium aluminate solution to remove rolling oil on the surface of a 0.3 mm thick aluminum plate (material 1050) The aluminum surface was grained using three bundle-planted nylon brushes having a bristle diameter of 0.3 mm and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. This plate was etched by being immersed in a 25 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 aqueous nitric acid solution (containing 0.5% by mass aluminum ions), and the liquid temperature was 50 ° C. The AC power supply waveform is electrochemical roughening treatment using a trapezoidal rectangular wave AC with a time 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 AC. 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.

Furthermore, in a 0.5% by weight aqueous solution of hydrochloric acid (containing 0.5% by weight of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C., an electrolytic solution of nitric acid is used under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. An electrochemical surface roughening treatment was performed in the same manner, followed by washing with water by spraying. The plate was provided with a direct current anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, then washed with water and dried. 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. Furthermore, the following undercoat liquid (1) was applied so that the dry coating amount was 6 mg / m ² to obtain a support.

-Undercoat liquid (1)-
Undercoat compound (1) (mass average molecular weight: 60,000) 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

(2) Formation of Image Recording Layer and Protective Layer An image recording layer coating solution having the following composition was bar coated on the support on which the undercoat layer had been formed, followed by oven drying at 100 ° C. for 60 seconds. An image recording layer of 0 g / m ² was formed. Subsequently, a protective layer coating solution having the following composition is bar-coated on the image recording layer and oven-dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.160 g / m ^2. I got the original version.
The image recording layer coating solution was obtained by mixing and stirring the following photosensitive solution and microgel solution (1) immediately before coating.

-Sensitive solution-
(D) Binder polymer (1) 0.177 g
(A) Radical generator (Exemplary Compound A-9) 0.142 g
(B) Infrared absorber (1) 0.0308 g
(C) Polymerizable compound (Aronix M-215 (manufactured by Toa Gosei Co., Ltd.)) 0.319 g
Phosphonium compound (1) 0.035 g
Fluorosurfactant (1) 0.004g
Anionic surfactant 0.125g
(Pionine A-24-EA (Takemoto Yushi Co., Ltd., 40% by mass aqueous solution)
Methyl ethyl ketone 2.554g
1-methoxy-2-propanol 7.023 g

-Microgel solution (1)-
Microgel dispersion (1) 1.800 g
1.678 g of water

-Synthesis of microgel dispersion (1)-
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75% by mass ethyl acetate solution) 10.0 g, as a polymerizable compound Aronix M-215 (Toa Synthesis Co., Ltd.) 6.00 g and Piionin A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 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 40 ° C. for 2 hours. The microcapsule liquid thus obtained was diluted with distilled water to a solid content concentration of 21% by mass to obtain a microgel dispersion (1). The average particle size was 0.23 μm.
The structure of each compound used in the photosensitive solution is shown below.

-Protective layer coating solution-
-Latex of Synthesis Example-1 4.01g
・ Nonionic surfactant 0.013g
(Emalex 710, manufactured by Nippon Emulsion Co., Ltd.)
・ Ion-exchanged water 6.0g

[Examples 2 to 8]
In Example 1, a lithographic printing plate precursor was prepared in the same manner as in Example 1 except that the type of latex in the protective layer coating solution, the amount of latex used, and the dry coating amount of the protective layer were changed as shown in Table 1. .

[Comparative Example 1]
A lithographic printing plate precursor was prepared in the same manner as in Example 1, except that the latex of Synthesis Example-1 in the protective layer coating solution was replaced with the latex of Comparative Synthesis Example-1.

[Comparative Example 2]
A lithographic printing plate precursor was prepared in the same manner as in Example 1 except that the latex of Synthesis Example-1 in the protective layer coating solution was replaced with the latex of Comparative Synthesis Example-2.

3. Evaluation of lithographic printing plate precursor The obtained lithographic printing plate precursor was exposed with a water-cooled 40W infrared semiconductor laser-mounted Creo Trendsetter 3244VX under conditions of an output of 11.7 W, an outer drum rotation speed of 250 rpm, and a resolution of 2400 dpi. As described above, on-machine developability, on-machine developability after high-temperature forced aging, and foaming property were evaluated. The results are shown in Table 2.

(Evaluation of on-press developability)
Further, the obtained exposed original plate is not developed and attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg, and dampening solution (EU-3 (Etchi solution manufactured by FUJIFILM Corporation) / water / isopropyl. Alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.), and after supplying fountain solution and ink, 6,000 per hour Printing was performed at the printing speed of the sheet. At this time, the number of printing sheets (on-press developability) required until the ink was not transferred to the unexposed portion (non-image portion) of the image recording layer was evaluated. The smaller the number, the better the on-press developability.

(Evaluation of on-press developability after high temperature forced aging)
After the lithographic printing plate precursor was prepared, the lithographic printing plate precursor was allowed to stand for 48 hours at a temperature of 65 ° C. and a relative humidity of 65%, and then the on-press developability was evaluated in the same manner.

(Evaluation of foaming properties)
30 ml of the protective layer coating solution was placed in a transparent bottle, and raised and lowered 15 cm at a rate of once per second was repeated 5 times. Immediately after that, the height of foaming was measured.

From the results shown in Table 2, it was found that the lithographic printing plate precursor to which the protective layer of the present invention was applied was excellent in antifoaming property when coated with the protective layer, on-press developability, and on-press developability after aging.
In particular, it is considered that the on-press developability after aging is improved by the ternary polymer latex (crosslinked particles) because the fusion of the latex particles contained in the protective layer over time is suppressed.

Claims (11)

  A lithographic plate comprising a protective layer containing a polymer latex synthesized by polymerizing a polymerizable monomer in which 50% by mass or more of the total polymerizable monomer is acrylonitrile in the absence of a surfactant and a protective colloid A printing plate master.   The lithographic printing plate precursor as claimed in claim 1, wherein the polymer latex has an average particle size of 3 µm or less.   2. An image recording layer comprising (A) a radical generator, (B) a sensitizing dye, and (C) a compound having at least one addition-polymerizable ethylenically unsaturated bond. The lithographic printing plate precursor as described in any one of 2 above.   The lithographic printing plate precursor as claimed in claim 3, wherein the sensitizing dye (B) is an infrared absorber.   The lithographic printing plate precursor as claimed in any one of claims 3 to 4, wherein the image recording layer is removable with printing ink and / or fountain solution.   The lithographic printing plate precursor as claimed in any one of claims 3 to 5, wherein the image recording layer further comprises (D) a binder polymer.   The lithographic printing plate precursor as claimed in any one of claims 3 to 6, wherein the image recording layer further comprises (E) a microcapsule or a microgel.   On the support, it has an image recording layer that can be recorded by infrared laser exposure, and after image recording by infrared laser, it is mounted on a printing machine without passing through a development processing step, or image recording by infrared laser after mounting the printing machine The lithographic printing plate precursor according to any one of claims 3 to 7, wherein printing is possible.   The lithographic printing plate precursor as claimed in any one of claims 1 to 8, wherein the polymer latex is copolymerized with a bifunctional or higher polymerizable monomer.   The lithographic printing plate precursor according to any one of claims 1 to 9, wherein the surfactant content of the coating solution for forming the protective layer is 0.2% by mass or less.   The step of exposing the lithographic printing plate precursor according to any one of claims 1 to 10 imagewise with an infrared laser, and without performing any development treatment on the exposed lithographic printing plate precursor, A lithographic printing method comprising: a printing step of supplying an aqueous component and printing, wherein an infrared laser unexposed portion of the lithographic printing plate precursor image recording layer is removed during the printing step.