JP2008276155A - Lithographic printing plate precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate precursor which can be favorably developed with a developer having pH of 2.0-6.5 and can prepare a lithographic printing plate excellent in printing durability and stain resistance. <P>SOLUTION: The lithographic printing plate precursor includes on a support a photosensitive layer containing (A) a binder polymer containing a positively charged nitrogen atom in a main chain and/or a side chain of the binder polymer, (B) a compound containing an ethylenically unsaturated bond and (C) a radical polymerization initiator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate precursor and an image forming method.

In general, a lithographic printing plate has a surface composed of an oleophilic image portion and a hydrophilic non-image portion. In lithographic printing, dampening water and oil-based ink are alternately applied to the plate surface, and the hydrophilic non-image area is dampened with a dampening water receiving area (ink non-receiving area) by utilizing the property that water and oil repel each other. ), After the ink is received only in the oleophilic 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 layer (image recording layer) is provided on a hydrophilic support has been widely used. Normally, after exposing a lithographic printing plate precursor through an original image such as a lithographic film, the photosensitive layer to be an image portion is left, and other unnecessary photosensitive layers are dissolved with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method of exposing the surface of the hydrophilic support to form a non-image portion by removing it.

  In the conventional plate-making process of a lithographic printing plate precursor, a step of dissolving and removing unnecessary photosensitive layers with a developer or the like is necessary after exposure, but simplifies such additional wet processing. Is listed as one of the issues. As one of simplification, it is desired that development can be performed with an aqueous solution close to neutrality or simple water.

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

  From the background as described above, it is now more strongly desired than ever to adapt both the simplification of the plate making operation and the digitization.

  On the other hand, for example, in Patent Document 1, in an image forming layer of a lithographic printing plate precursor having an image forming layer containing a hydrophobizing precursor, a hydrophilic resin, and a photothermal conversion agent on a hydrophilic support. In addition to the on-press development, it can also be used for printing after exposure by liquid development using water or a suitable aqueous solution as a developer by further containing a compound having an ethylene oxide chain. Has been.

  Patent Document 2 contains (i) a hydrophilic support, and (ii) a radical polymerizable ethylenically unsaturated monomer, a radical polymerization initiator and an infrared absorbing dye, and is cured by infrared laser exposure. Moreover, a lithographic printing plate precursor comprising an oleophilic heat-sensitive layer containing 60% by mass or more of water and developable with an aqueous developer having a pH of 2.0 to 10.0 is prepared and exposed imagewise with an infrared laser. A processing method for a lithographic printing plate precursor comprising removing an uncured region of the heat-sensitive layer with an aqueous developer is described.

On the other hand, as a photosensitive resin composition having an ammonium salt, a photosensitive resin composition introduced by opening an epoxy group with an amino group is known (see Patent Documents 3 to 5). It is not shown that both developability and printing durability can be achieved when used in the above. Also,
When a binder polymer having a hydroxyl group is used, the soiling property due to adsorption to the substrate is deteriorated, which causes a practical problem.
JP 2002-365789 A US Patent Application Publication No. 2004/0013968 JP-A-6-59448 JP-A-6-202329 JP-A-8-109232

  In order to maintain the developability of the aqueous developer having a pH of 2.0 to 10.0 as described above, and the aqueous developer of pH 2.0 to 6.5 having a lower pH, the photosensitive layer is hydrophilic or has high water penetration. The photosensitive layer cured by exposure has insufficient water resistance and film strength. In addition, when the binder polymer used in the conventional lithographic printing plate precursor is applied, there is a problem that the stain resistance cannot be satisfied by aqueous development at pH 2.0 to 6.5. In order to solve these problems, the photosensitive layer cured by laser exposure can impart excellent printing durability to the image area, and the photosensitive layer in the unexposed area is excellent by an aqueous developer having a pH of 2.0 to 6.5. Therefore, it is necessary to provide a lithographic printing plate precursor and an image forming method that can be removed.

  The present inventor has found that the above problem can be solved by incorporating a binder polymer having a positively charged nitrogen atom in the main chain and / or side chain into the photosensitive layer. That is, the present invention is as follows.

1. A lithographic printing plate precursor having a photosensitive layer containing the following (A) to (C) on a support.
(A) Binder polymer having a positively charged nitrogen atom in the main chain and / or side chain (B) Compound having an ethylenically unsaturated bond (C) Radical polymerization initiator (A) The above 1 wherein the binder polymer having a positively charged nitrogen atom in the main chain and / or side chain has a group represented by any of the following general formulas (1) to (4) Lithographic printing plate precursor.

In the formula, R _{1 to} R ₇ each represent a monovalent substituent, and X ⁻ represents an anion. Any _{two of} R ₁ and R ₂ and R _{4 to} R ₆ may be bonded to each other to form a ring.

3. (A) The lithographic printing plate precursor as described in 1 or 2 above, wherein the binder polymer having a positively charged nitrogen atom in the main chain and / or side chain is a (meth) acrylic resin or a urethane resin.
4). (A) The lithographic printing plate precursor as described in 1 or 2 above, wherein the binder polymer having a positively charged nitrogen atom in the main chain and / or side chain is a urethane resin.
5. In the general formulas (1) to (4), at least one of R ₁ and R ₂ , R ₃ ,
The lithographic printing plate precursor as described in any one of 1 to 4 above, wherein at least one of R _{4 to} R ₆ and R ₇ are hydrogen atoms.
6). The lithographic printing plate precursor as described in any one of 1 to 5 above, wherein the photosensitive layer further contains (D) a sensitizing dye.
7). After the lithographic printing plate precursor according to any one of 1 to 6 above is image-exposed with a laser, the unexposed photosensitive layer is removed in the presence of a developer having a pH of 2 to 6.5. An image forming method.

  Although the mechanism of action of the present invention is not clear, the following is presumed. Conventionally, developability to a developer having a pH of 2.0 to 10.0 has been imparted by increasing the hydrophilicity of the binder polymer, but this also means that the developer and dampening water are significantly penetrated into the exposed area. Inevitably, this was a major factor that deteriorated printing durability. The binder polymer having a positively charged nitrogen atom in the main chain and / or side chain of the present invention, preferably selected from the structures represented by the following general formulas (1) to (4) in the main chain and / or side chain. By introducing a specific salt structure such as a binder polymer having at least one group, the interaction between the binder polymer and the surfactant is improved, and developability to a developer having a pH of 2.0 to 6.5 is imparted. Think of it as possible. In addition, the specific salt structure selected from the structures represented by the general formulas (1) to (4) is currently considered to be able to improve the adhesion with the substrate or the undercoat layer. It is presumed that the permeability of the developer and dampening water at pH 2.0 to 6.5 can sometimes be lowered, and the printing durability is improved. These actions are considered to have achieved the contradictory performances of developability and printing durability with a developer having a pH of 2.0 to 6.5.

  According to the present invention, a lithographic printing plate capable of producing a lithographic printing plate that can be satisfactorily developed with a developer having a pH of 2.0 to 6.5, has excellent printing durability, and has excellent stain resistance. The original version can be provided.

  Hereinafter, the photosensitive layer, the lithographic printing plate precursor, and the image forming method according to the present invention will be described in detail.

(Photosensitive layer)
The photosensitive layer of the lithographic printing plate precursor according to the invention has a binder polymer having a positively charged nitrogen atom in the main chain and / or side chain, preferably the following general formulas (1) to ( 4) A binder polymer having at least one group selected from the structure represented by 4), a compound having an ethylenically unsaturated bond, and a radical polymerization initiator.
Hereinafter, the components of the polymerizable composition constituting the photosensitive layer will be described in more detail.

(Binder polymer having a positively charged nitrogen atom in the main chain and / or side chain)
The binder polymer having a positively charged nitrogen atom in the main chain and / or side chain of the present invention (hereinafter appropriately referred to as a specific binder polymer) is an ammonium salt in the main chain and / or side chain portion of the polymer chain. Any compound may be used as long as it is a polymer having a structure. A binder polymer having at least one group selected from structures represented by the following general formulas (1) to (4) in the main chain and / or side chain is preferable. The binder polymer having at least one group selected from the structures represented by the following general formulas (1) to (4) in the main chain and / or side chain is represented by the general formulas (1) to (4). Any compound may be used as long as the polymer compound has at least one group as a repeating unit.

Here, in general formulas (1) to (4), R _{1 to} R ₇ each independently represents a monovalent substituent. Here, the monovalent substituent is a substituent consisting of at least one atom selected from hydrogen, carbon, oxygen, nitrogen, sulfur, phosphorus, halogen and silicon. Further, any _{two of} R _1, R ₂ and R _{4 to} R ₆ may be bonded to each other to form a ring. The substituent consisting of at least one atom selected from hydrogen, carbon, oxygen, nitrogen, sulfur, phosphorus, halogen, and silicon is -H, -F, -Cl, -Br, -I,> C <, = C <, ≡C-, -O-, O =, -N <, -N =, ≡N, -S-, S =,> S <, ≡S≡, -P <, ≡P <,> Si <, ═Si <, ≡Si— and monovalent substituents formed by combining these. Monovalent substituents include hydrogen atoms, alkyl groups [eg, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl. Group, tridecyl group, hexadecyl group, octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2 -Methylhexyl, cyclohexyl, cyclopentyl, 2-norbornyl, chloromethyl, bromomethyl, 2-chloroethyl, trifluoromethyl, methoxymethyl, methoxyethoxyethyl, allyloxymethyl, phenoxymethyl Methylthiomethyl group, tolylthiomethyl group, Tylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamoyloxyethyl group, N-phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl Group, 2-oxoethyl group, 2-oxopropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxycarbonylbutyl group, chlorophenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-di Propylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfophenyl) carbamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group, N-methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group , Phosphonatohexyl group, Diethylphosphonobutyl group, Diphenylphosphonopropyl group, Methylphosphonobutyl group, Methylphosphonobutyl group, Tolylphosphonohexyl group, Tolylphosphonatohexyl group, Phosphonoxypropyl group, Phosphonato Oxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methylbenzyl group, etc.], aryl group [eg, phenyl group, biphenyl group, naphthyl group, tolyl group Xylyl group, mesityl group, cumenyl group, chlorophenyl group, Lomophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylamino Phenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group, ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, nitrophenyl group, cyanophenyl group, sulfophenyl group, sulfonatophenyl group , Phosphonophenyl group, phosphonatophenyl group, etc.), heteroaryl group (for example, thiophene, thiathrene, furan, pyran, isobenzofuran, chromene, Nten, phenoxazine, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indoir, indazole, purine, quinolidine, isoquinoline, phthalazine, naphthyridine, quinazoline, sinoline, pteridine, carbazole , A carboline, a phenanthrine, an acridine, a perimidine, a phenanthroline, a phthalazine, a phenazazine, a phenoxazine, a furan, a group derived from a hetero ring such as phenoxazine, an alkenyl group (for example, a vinyl group, a 1-propenyl group, a 1- Butenyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 1-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-chloro-1-ethenyl group, etc.], alkynyl group [example For example, an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a trimethylsilylethynyl group, etc.), a halogen atom [—F, —Br, —Cl, —I ], Hydroxyl group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N , N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkyls Hoxy group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N ′ -Arylureido group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N ′, N′-dialkyl-N-arylureido group, N′-aryl-N-alkylureido group, N′-aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-arylureido group, N′-alkyl-N′-aryl-N -Alkylurei Group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonyl Amino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkyl Carbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group , a sulfo group (-SO ₃ H And its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl Group, N, arylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonate group), dialkylphosphono group (-PO ₃ (alkyl) ₂ ), diaryl phosphono group (-PO ₃ (aryl) ₂ ), alkyl aryl phosphono group (—PO ₃ (alkyl) (aryl)), monoalkyl phosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkyl phosphonate group), monoaryl phosphono group (—PO 3 ₃ H (aryl)) and its conjugate base group (hereinafter referred to as aryl phosphonate group), phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonateoxy group), dialkyl Phosphonooxy group (—OPO ₃ (alkyl) ₂ ), diaryl phosphonooxy group (—OPO ₃ (aryl) ₂ ), alkylaryl phosphonooxy group (—OPO ₃ (alkyl) (aryl)), monoalkyl phosphine A phonooxy group (—OPO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as an alkylphosphonatooxy group), a monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group ( After that, And a cyano group, a nitro group, and the like. A hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a halogen atom, an alkoxy group, and an acyl group are preferable, and printing durability , A hydrogen atom, an alkyl group, and an aryl group are more preferable from the viewpoints of developability with a developer having a pH of 2.0 to 6.5 and stain resistance, and a hydrogen atom or the total number of carbon atoms of R _{1 to} R ₂ , R ₃ More preferred are alkyl groups and aryl groups in which the total number of carbon atoms in R ₄ , R _{4 to} R ₆ , and R ₇ have 1 to 12 carbon atoms, respectively. More preferably, at least one of R ₁ and R ₂ , R _3, at least one of R _{4 to} R ₆ , and R ₇ are hydrogen atoms.

Among general formulas (1) to (4), the most preferable structure is general formula (3). In particular, it is preferable that one of R _{4 to} R _{6 in} the general formula (3) is a hydrogen atom, and the remaining two are an alkyl group or an aryl group. Further, an alkyl group or an aryl group having a total of the remaining two carbon atoms of 1 to 12 is more preferable.

In the general formulas (1) to (4), X ⁻ is an anion. Specific examples thereof include halogen anions, halogen oxoacid anions (ClO ₄ ⁻ , IO ₃ ⁻ , BrO ₃ ⁻ , etc.), halogeno complexes. ion _{^{(BF 4 -, PF 6 -}} , AlCl 4 -, etc.), a sulfate anion, nitrate anion, phosphate anion, a borate anion, a carboxylate anion, sulfonate anion, a phosphonate anion and a metal complex anion ([Fe (CN ) ₆ ] ^- , etc.). Among these, a halogen anion, a halogeno complex ion, a borate anion, a carboxylate anion, and a sulfonate anion are preferable, and a halogeno complex ion, a borate anion, and a sulfonate anion are more preferable from the viewpoint of printing durability and stain resistance.

Any method may be used for introducing the ammonium salt into the polymer. For example, a method of copolymerizing a quaternary ammonium group-containing acrylate monomer exemplified by [Chemical Formula 3] with another vinyl compound, The tertiary amine-containing acrylate monomer exemplified in [Chemical Formula 4] is copolymerized with another vinyl compound, and then neutralized with an acid and quaternary ammonium chloride or quaternary with an alkylating agent. A method of ammonium salification, a method of copolymerizing a quaternary ammonium group-containing diol compound exemplified in [Chemical Formula 5] with an isocyanate, a carboxylic acid and a carboxylic acid derivative, and a tertiary amine-containing diol exemplified in [Chemical Formula 6] Is copolymerized with isocyanate, carboxylic acid, carboxylic acid derivative, and then neutralized with acid to produce tertiary ammonium chloride or alkyl Quaternary ammonium how to chloride by agents.
In addition, examples of introduction sites include introduction to random side chains and main chains, introduction to block side chains and main chains, terminal capping and introduction to polymer ends, as described above, synthesis of macromonomers, grafting From the viewpoint of developability, introduction into a main chain or side chain in a random or block manner or introduction after grafting is preferable.

Specific examples of acids used to neutralize with acids to form tertiary ammonium salts include hydrohalic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid Mineral acids such as tetrafluoroboric acid and pentafluorophosphoric acid, halogen oxo acids such as perchloric acid, benzoic acid, 2,5-dichlorobenzoic acid, 3,5-dichlorobenzoic acid, pentafluoro Benzoic acid, 4-methoxybenzoic acid, 3,4-dimethoxybenzoic acid, 4-bromobenzoic acid, 4-dimethylaminobenzoic acid, 4-diethylaminobenzoic acid, 1-naphthoic acid, 4-nitrobenzoic acid, 4-phenyl Carboxylic acids such as benzoic acid, toluic acid, benzoylformic acid, acetic acid, tert-butylacetic acid, lauric acid, behenic acid, stearyl acid, nonanoic acid, 3-cyclohexanebutanoic acid, etc. 4-amino-1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 2,4,5-trichlorobenzenesulfonic acid, dansylic acid, p-xylene-2-sulfonic acid, 2,4-dinitrobenzene acid methanesulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 4-nitrobenzenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, 4-ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, ethanesulfonic acid, propanesulfonic acid, amino Ethanesulfonic acid, 2-cyclohexylaminoethanesulfonic acid, (+)-10-camphorsulfonic acid, sulfonic acid such as 3-hydroxypropanesulfonic acid, alkyl sulfuric acid such as 2-aminoethyl hydrogensulfate, ethyl phosphate, butyl phosphate Dibutylphos Eto, and the like phosphoric acids such as phenyl phosphonic acid. Among these, nonvolatile carboxylic acid, sulfonic acid, and phosphonic acid are preferable from the viewpoint of image formation stability. From the viewpoint of printing durability, the log P value of the neutralized acid is preferably 6 or less, preferably 4 or less, and more preferably 2 or less (here, the log P value is the distribution coefficient P ( This is a common logarithm of (Partition Coefficient). It is a physical property value that expresses how an organic compound is distributed in the equilibrium of a two-phase system of oil (generally 1-octanol) and water as a quantitative value. Log P = log (Coil / Cwater) Coil = Molar concentration in oil phase Cwater = Molar concentration in water phase) From the viewpoint of sensitivity, the pKa of the neutralized acid is preferably -5 to 8, more preferably -3 to 6, and further preferably -1 to 4. Specific examples of the neutralizing acid satisfying these include benzoic acid, 2,5-dichlorobenzoic acid, 3,5-dichlorobenzoic acid, pentafluorobenzoic acid, benzoylformic acid, lauric acid carboxylic acid, 2-naphthalenesulfonic acid, 2,4,5-trichlorobenzenesulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, 4-ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, ethanesulfonic acid, More preferred are propanesulfonic acid, (+)-10-camphorsulfonic acid sulfonic acid.

  Furthermore, allyloxypropionic acid, acrylamide hexanoic acid, 3-butenoic acid, acrylic acid, methacrylic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl phthalic acid, 2 -Carboxylic acids having radically polymerizable unsaturated double bonds such as methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 4-vinylbenzoic acid, etc. A sulfonic acid having a radically polymerizable unsaturated double bond such as 2-acrylamido-2-methylpropanesulfonic acid or 4-vinylbenzenesulfonic acid is more preferable from the viewpoints of sensitivity and printing durability.

Moreover, as an alkylating agent used in order to make a quaternary ammonium salt with an alkylating agent, a chlorinated product (R-Cl), a brominated product (R-Br), an iodinated product (R-1), a sulfate ester ( R′O—SO ₂ —OR ′), sulfonic acid ester (R′—SO ₂ —OR) and the like. Specific examples of these alkylating agents include dialkyl sulfuric acid, alkyl paratoluenesulfonate, alkyl-trifluoromethanesulfonate, alkyl trifluoromethanesulfonate (triflate), alkyl methanesulfonate (mesylate) and the like. Specific examples of such alkylating agents include chloromethane, chloroacetic acid, chloropropionic acid, iodomethane, 1-iodoethane, 1-iodooctane, bromomethane, 1-bromoethane, 1-bromohexane, 3-bromopropionic acid. n-methyl, dimethyl sulfate, diethyl sulfate, dibutyl sulfate, diamyl sulfate, dihexyl sulfate, dioctyl sulfate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, n-hexyl p-toluenesulfonate, p-toluenesulfonic acid n-octyl, methyl methanesulfonate, ethyl methanesulfonate, n-hexyl methanesulfonate, and the like. Iodomethane, 1-iodoethane, dimethyl sulfate, diethyl sulfate, methyl p-toluenesulfonate, p-toluenesulfonic acid Ethyl, methane Methyl sulfonic acid are preferable from the viewpoint of hydrophobicity and counter anion of quaternary ammonium salt.

  The skeleton structure of the specific binder polymer is arbitrary as long as it has at least one group selected from the structures represented by the general formulas (1) to (4) in the main chain and / or the side chain. However, as a chain polymerization resin, (meth) acrylic resin, styrene resin, epoxy resin, polyvinyl acetal resin, and as sequential polymerization resin, polyurethane resin, polyamide resin, polyester resin, polyurea resin From the viewpoints of synthesis suitability, film properties, printing durability, and developability, (meth) acrylic resins and styrene resins are preferred as chain polymerization resins, and polyurethanes as sequential polymerization resins are preferred. A resin is further preferred.

  The specific binder polymer of the present invention is represented by a compound having at least one group selected from the structures represented by the general formulas (1) to (4) and the general formulas (1) to (4). It may be a copolymer with another copolymerizable compound having no structure. Of the copolymerizable compounds, examples of the chain polymerization compound include the compounds listed in the following (m1) to (m11).

(M1) For example, acrylic esters and methacrylic esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  Examples of the sequential polymerization compound copolymerizable with a compound having at least one group selected from the structures represented by the general formulas (1) to (4) include the following bifunctional compounds: (Diamine compounds, dicarboxylic acids or derivatives thereof, diisocyanate compounds, diol compounds).

Examples of the diamine compound include those shown below.
Ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, 1,2-diamino-2-methylpropane, 1,5-diaminopentane, 2,2-dimethyl-1,3 -Propanediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecene, 4,4'-methylenebis (cyclohexylamine), 1,2-diaminocyclohexane, 1,4 -Aliphatic diamines such as diaminocyclohexane, isophorone diamine, 2,2 '-(ethylenedioxy) -bis (ethyleneamine), 4,7,10-trioxa-1,13-tridecanediamine, 1,2- Phenylenediamine, 2,3-diaminotoluene, 3,4-diaminotoluene, 4-chloro-1,2 -Phenylenediamine, 4,5-dimethyl-1,2-phenylenediamine, 4,5-dichloro-1,2-phenylenediamine, 1,3-phenylenediamine, 2,6-diaminotoluene, 2,4-diaminotoluene 2,4,6-trimethyl-1,3-phenylenediamine, 1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, 2,5-dichloro-1,4-phenylenediamine, 4, , 4 ′-(hexafluoroisopropylidene) diamine, 2,3-diaminonaphthalene, 1,5-diaminonaphthalene, p-xylenediamine, 4-aminobenzylamine, 2- (4-aminophenyl) ethyleneamine, bis ( Aromatic diamines such as 4-aminophenylmethane) and bis (4-aminophenyl) ether, etc. Of these, aromatic diamine compounds and aliphatic diamine compounds having 2 to 10 carbon atoms are particularly preferable.

  Dicarboxylic acids or their derivatives include succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, 1, Examples include 4-cyclohexanedicarboxylic acid, carboxynorbornanoic acid, 5-sodium sulfoisophthalic acid, 4-hydroxybenzylidene malonic acid, 3-hydroxyphthalic acid and other dicarboxylic acids or derivatives thereof. Among them, dicarboxylic acids having aromaticity or A derivative thereof, an aliphatic dicarboxylic acid having 2 to 10 carbon atoms or a derivative thereof is particularly preferred.

The specific polyamide resin according to the present invention can be easily produced by a method described in, for example, “New Polymer Experiments 3 Synthesis and Reaction of Polymers (2)” edited by Kyoritsu Publishing Co., Ltd.

As a diisocyanate compound, it represents with General formula (5). The diol compound is represented by the general formula (6). In the general formulas (5) and (6), X ⁰ and Y ⁰ each independently represent a divalent organic residue.

OCN-X ⁰ -NCO (5)
HO-Y ⁰ -OH (6)

  Specific examples of the diisocyanate compound represented by the general formula (5) include those shown below. That is, 2,4-tolylene diisocyanate, dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate Aromatic diisocyanate compounds such as 1,5-naphthylene diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer acid diisocyanate, etc. Aliphatic diisocyanate compounds; isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) diiso Alicyclic diisocyanate compounds such as cyanate and 1,3- (isocyanatomethyl) cyclohexane; a reaction product of diol and diisocyanate such as an adduct of 1 mol of 1,3-butylene glycol and 2 mol of tolylene diisocyanate A diisocyanate compound; and the like.

  Examples of the diol compound represented by the general formula (6) include a polyether diol compound, a polyester diol compound, and a polycarbonate diol compound.

  Examples of the polyether diol compound include compounds represented by the following formulas (7), (8), (9), (10) and (11), and random copolymerization of ethylene oxide and propylene oxide having a hydroxyl group at the terminal. Coalescence is mentioned.

In formulas (7) to (11), R ¹⁴ represents a hydrogen atom or a methyl group, and X ¹ represents the following group. Moreover, a, b, c, d, e, f and g each represent an integer of 2 or more, preferably an integer of 2 to 100.

  Specific examples of the polyether diol compound represented by the above formulas (7) and (8) include the following. That is, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, heptaethylene glycol, octaethylene glycol, di-1,2-propylene glycol, tri-1,2-propylene glycol, tetra-1, 2-propylene glycol, hexa-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propylene glycol, tetra-1,3-propylene glycol, di-1,3-butylene glycol, Tri-1,3-butylene glycol, hexa-1,3-butylene glycol, polyethylene glycol having a weight average molecular weight of 1000, polyethylene glycol having a weight average molecular weight of 1500, poly having a weight average molecular weight of 2,000 Tylene glycol, polyethylene glycol having a weight average molecular weight of 3000, polyethylene glycol having a weight average molecular weight of 7500, polypropylene glycol having a weight average molecular weight of 400, polypropylene glycol having a weight average molecular weight of 700, polypropylene glycol having a weight average molecular weight of 1000, polypropylene glycol having a weight average molecular weight of 2000 , Polypropylene glycol having a weight average molecular weight of 3000, polypropylene glycol having a weight average molecular weight of 4000, and the like.

Specific examples of the polyether diol compound represented by the formula (9) include those shown below.
That is, Sanyo Chemical Industries, Ltd. (trade name) PTMG650, PTMG1000, PTMG2000, PTMG3000, and the like.

  Specific examples of the polyether diol compound represented by the formula (10) include those shown below. That is, Sanyo Chemical Industries, Ltd. (trade name) New Pole PE-61, New Pole PE-62, New Pole PE-64, New Pole PE-68, New Pole PE-71, New Pole PE-74, New Pole PE-75, New Pole PE-78, New Pole PE-108, New Pole PE-128, New Pole PE-61, and the like.

Specific examples of the polyether diol compound represented by the formula (11) include those shown below.
That is, Sanyo Chemical Industries, Ltd. (trade name) New Pole BPE-20, New Pole BPE-20F, New Pole BPE-20NK, New Pole BPE-20T, New Pole BPE-20G, New Pole BPE-40, New Pole BPE-60, New Pole BPE-100, New Pole BPE-180, New Pole BPE-2P, New Pole BPE-23P, New Pole BPE-3P, New Pole BPE-5P, and the like.

  Specific examples of the random copolymer of ethylene oxide and propylene oxide having a hydroxyl group at the terminal include the following. That is, Sanyo Chemical Industries, Ltd. (trade name) New Pole 50HB-100, New Pole 50HB-260, New Pole 50HB-400, New Pole 50HB-660, New Pole 50HB-2000, New Pole 50HB-5100, etc. It is.

  Examples of the polyester diol compound include compounds represented by formulas (12) and (13).

In formulas (12) and (13), L ² , L ³ and L ⁴ may be the same or different.
Represents a divalent aliphatic or aromatic hydrocarbon group, and L ⁵ represents a divalent aliphatic hydrocarbon group. Preferably, L ^{2 to} L ⁴ each represent an alkylene group, an alkenylene group, an alkynylene group, or an arylene group, and L ⁵ represents an alkylene group. In addition, other functional groups that do not react with the isocyanate group, such as ether, carbonyl, ester, cyano, olefin, urethane, amide, ureido group or halogen atom may be present in L ^{2 to} L ⁵ . n1 and n2 are each an integer of 2 or more, preferably an integer of 2 to 100.

  As the polycarbonate diol compound, there is a compound represented by the formula (14).

In the formula (14), L ⁶ may be the same or different and each represents a divalent aliphatic or aromatic hydrocarbon group. Preferably, L ⁶ represents an alkylene group, an alkenylene group, an alkynylene group or an arylene group. In addition, other functional groups that do not react with the isocyanate group, such as ether, carbonyl, ester, cyano, olefin, urethane, amide, ureido group or halogen atom may be present in L ⁶ . n3 is an integer of 2 or more, and preferably represents an integer of 2 to 100.

  Specific examples of the diol compound represented by the above formula (12), (13) or (14) include (Exemplary Compound No. 1) to (Exemplary Compound No. 18) shown below. N in the specific examples represents an integer of 2 or more.

  Furthermore, the specific binder polymer can be provided with a crosslinking property in order to improve the film strength of the image area. In order to give the specific binder polymer crosslinkability, a crosslinkable functional group may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization or may be introduced by a polymer reaction.

  Here, the crosslinkable functional group is a group that crosslinks the binder polymer in the process of radical polymerization reaction that occurs in the photosensitive layer when the lithographic printing plate precursor is exposed. Although it will not specifically limit if it is a group of such a function, For example, an ethylenically unsaturated bond group, an epoxy group, etc. are mentioned as a functional group which can be addition-polymerized. Moreover, the functional group which can become a radical by light irradiation may be sufficient, As such a crosslinkable functional group, a thiol group, a halogen group, an onium salt structure etc. are mentioned, for example. Especially, an ethylenically unsaturated bond group is preferable and the functional group represented by the following general formula (i)-(iii) is especially preferable.

In the general formula (i), R ^{1 to} R ³ each independently represents a hydrogen atom or a monovalent organic group, and R ¹ is preferably a hydrogen atom or an alkyl which may have a substituent. A hydrogen atom or a methyl group is preferable because of high radical reactivity. R ² and R ³ are each independently a hydrogen atom, a halogen atom, an amino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyano group, an optionally substituted alkyl group, or a substituted group. An aryl group which may have a group, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, and a substituent An arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, an arylsulfonyl group which may have a substituent, and the like. Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, a substituent An alkyl group which may have a substituent and an aryl group which may have a substituent are preferable because of high radical reactivity.

X represents an oxygen atom, a sulfur atom, or —N (R ¹² ) —, and R ¹² represents a hydrogen atom or a monovalent organic group. Here, examples of the monovalent organic group include an alkyl group which may have a substituent. Among them, R ¹² is a hydrogen atom, a methyl group, an ethyl group, or an isopropyl group having a high radical reactivity. This is preferable.

  Here, examples of the substituent that can be introduced include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, A sulfo group, a nitro group, a cyano group, an amide group, an alkylsulfonyl group, an arylsulfonyl group and the like can be mentioned.

In the general formula (ii), R ^{4 to} R ⁸ each independently represents a hydrogen atom or a monovalent organic group, and R ^{4 to} R ⁸ are preferably a hydrogen atom, a halogen atom, an amino group, or a dialkyl. Amino group, carboxyl group, alkoxycarbonyl group, sulfo group, nitro group, cyano group, alkyl group which may have a substituent, aryl group which may have a substituent, alkoxy which may have a substituent A group, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, Examples include an arylsulfonyl group which may have a substituent. Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, an alkyl group which may have a substituent, and an aryl which may have a substituent Group is preferred.

Examples of the substituent that can be introduced are the same as those in the general formula (i). Y represents an oxygen atom, a sulfur atom, or —N (R ¹² ) —. R ¹² has the same meaning as R ^{12 in} formula (i), and preferred examples are also the same.

In the general formula (iii), R ⁹ represents a hydrogen atom or a monovalent organic group, and preferably includes a hydrogen atom or an alkyl group which may have a substituent. Among them, a hydrogen atom A methyl group is preferred because of high radical reactivity. R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyano group, or an alkyl group which may have a substituent. An aryl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, An arylamino group which may have, an alkylsulfonyl group which may have a substituent, an arylsulfonyl group which may have a substituent, etc. are mentioned, among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, An alkyl group which may have a substituent and an aryl group which may have a substituent are preferable because of high radical reactivity.

Here, examples of the substituent that can be introduced are the same as those in the general formula (i). Further, Z is an oxygen atom, a sulfur atom, -N (R ¹³⁾ -, or a phenylene group which may have a substituent. Examples of R ¹³ include an alkyl group which may have a substituent. Among them, a methyl group, an ethyl group, and an isopropyl group are preferable because of high radical reactivity.

  Among the above, the specific binder polymer having crosslinkability is more preferably a (meth) acrylic acid copolymer having a crosslinkable functional group in the side chain and polyurethane.

  The specific binder polymer having crosslinkability is, for example, a free radical (polymerization initiation radical or a growth radical in the polymerization process of a polymerizable compound) is added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is directly between the polymers. Through addition polymerization, a crosslink is formed between the polymer molecules to cure. Alternatively, atoms in the polymer (for example, hydrogen atoms on carbon atoms adjacent to the crosslinkable functional group) are extracted by free radicals to form polymer radicals that are bonded to each other, thereby causing crosslinking between polymer molecules. Forms and cures.

  The specific binder polymer 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 250,000. Is more preferable. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10. The specific binder polymer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

  The specific binder polymer may be used alone or in combination of two or more.

  In the specific binder, the structure represented by the general formulas (1) to (4) is preferably included as a repeating unit in an amount of 0.1 to 90 mol%, more preferably 3 to 50 mol%, and more preferably 5 to 30 mol%. It is more preferable to include.

  The content of the specific binder polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass with respect to the total solid content of the photosensitive layer.

Specific examples of the specific binder polymer containing the structures represented by the general formulas (1) to (4) as repeating units are listed below, but are not limited thereto.
The mass average molecular weight (Mw) in the table is measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.
In PB-1 to 100, the numerical value described together with the compound is the reaction ratio (mol%) of each constituent component. In the table, for example, “PPG1000” represents polypropylene glycol having an average molecular weight of 1000.

  Below, the synthesis example of the specific binder polymer of this invention is shown.

<Synthesis of Exemplary Compound (PA-1)>
A 500 mL three-necked flask equipped with a condenser and a stirrer was charged with 56 g of 1-methoxy-2-propanol and heated to 70 ° C. Under nitrogen flow, methyl acrylate 25.83g, 3-
A solution prepared by dissolving 44.34 g of (methacryloyloxy) propyltrimethylammonium chloride and 0.62 g of V-65 (trade name: polymerization initiator manufactured by Wako Pure Chemical Industries, Ltd.) with 56 g of 1-methoxy-2-propanol was added dropwise over 2 and a half hours. . The mixture was further reacted at 70 ° C. for 2 hours. Next, the reaction solution was poured into water to precipitate a copolymer. This was collected by filtration, washed and dried to obtain a binder polymer (PA-1). It was confirmed from the NMR spectrum, IR spectrum, and GPC that the product was the object.

<Synthesis of Exemplary Compound (PB-16)>
(Synthesis of 3- (3- (2,3-dihydroxypropylthio) propanamide) -N, N, N-trimethylpropaneammonium chloride)
Into a 300 mL eggplant-shaped flask, 54.08 g of 3-mercapto-1,2-propanediol was introduced, and 7 of 3- (acrylamidopropyl) trimethylammonium chloride was added using a dropping funnel.
A 5% by mass aqueous solution was added dropwise, and the mixture was stirred at room temperature for 3 hours. The completion of the reaction was confirmed by NMR, HPLC, IR spectrum, and mass spectrometry spectrum, and water in the reaction solution was removed by heating and drying under reduced pressure, and the obtained monomer was used as it was in the next reaction.

(Synthesis of (PB-16))
In a 500 mL three-neck flask equipped with a condenser and a stirrer, DMAc 42 g, polypropylene glycol (average molecular weight 1000) 20.0 g, 3- (3- (2,3-dihydroxypropylthio) propanamide) -N, N, N-trimethylpropane 9.45 g of ammonium chloride and 13.13 g of methylenediphenyl 4,4′-diisocyanate were introduced, and the reaction solution was brought to 50 ° C. to obtain a uniform solution. Two drops of neostan (manufactured by Nitto Kasei Co., Ltd .: bismuth catalyst) were added to the reaction solution and reacted at 80 ° C. for 4 hours. After adding 3.00 g of methanol to the reaction solution and quenching the reaction, the reaction solution was poured into 2 L of water to precipitate polyurethane. This is filtered. Washing and drying were performed to obtain a binder polymer (PB-16). It was confirmed from the NMR spectrum, IR spectrum, and GPC that the product was the object.

<Synthesis of Exemplified Compound (PB-30)>
In a 500 mL three-necked flask equipped with a condenser and a stirrer, 55 g of THF, 20.0 g of polypropylene glycol (average molecular weight 1000), 6.15 g of 3- (N, N-dimethylamino) -1,2-propanediol, Blemmer GLM (Nippon Yushi Co., Ltd.) (Made) 4.55 g, 20.60 g of methylenediphenyl 4,4′-diisocyanate, 3.46 g of hexamethylene diisocyanate, and 0.0884 g of benzoquinone were introduced, and the reaction solution was brought to 50 ° C. to obtain a uniform solution. Two drops of neostan (manufactured by Nitto Kasei Co., Ltd .: bismuth catalyst) were added to the reaction solution and reacted at 80 ° C. for 4 hours. To the reaction solution, 3.00 g of methanol was added to quench the reaction, and then 5.26 g of hydrochloric acid was added. The reaction solution was poured into 2 L of ethyl acetate to precipitate polyurethane. This is filtered. Washing and drying were performed to obtain a binder polymer (PB-30). It was confirmed from the NMR spectrum, IR spectrum, and GPC that the product was the object.

(Compound having an ethylenically unsaturated bond)
The polymerizable compound used in the photosensitive layer in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is a compound having at least one terminal ethylenically unsaturated bond, preferably two or more. To be elected. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or copolymers thereof and mixtures thereof. Examples of monomers include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably unsaturated carboxylic acids. An ester of an acid and an aliphatic polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and an aliphatic polyamine compound are used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and a monofunctional or polyfunctional compound. A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

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

  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 aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, JP-A-59- Those having an aromatic skeleton described in JP-A No. 5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

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

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

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56- Urethane compounds having an ethylene oxide skeleton described in Japanese Patent No. 17654, Japanese Patent Publication No. 62-39417, and Japanese Patent Publication No. 62-39418 are also suitable. 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 (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid-based compounds described in JP-A-2-25493 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 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 area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the compatibility and dispersibility with other components in the photosensitive layer (for example, binder polymer, polymerization initiator, colorant, etc.), the selection and use method of the polymerizable compound is an important factor. In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving adhesion to a support or a protective layer described later.

  The polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass, based on the total solid content of the photosensitive layer. These may be used alone or in combination of two or more. In addition, the usage method of the polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. The layer construction and coating method such as undercoating and overcoating can also be carried out.

(Radical polymerization initiator)
The radical polymerization initiator used in the photosensitive layer of the present invention is a compound that initiates and accelerates polymerization of a compound having a polymerizable unsaturated group by generating radicals by light or thermal energy. Such a radical polymerization initiator can be appropriately selected from known radical polymerization initiators and compounds having a bond having a small bond dissociation energy.
Examples of the radical polymerization initiator include organic halogen compounds, carbonyl compounds, organic peroxides, azo compounds, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, oxime ester compounds, oniums. A salt compound is mentioned.

Specific examples of the organic halogen compound include Wakabayashi et al., “Bull Chem.
c Japan "42, 2924 (1969), U.S. Pat. No. 3,905,815, JP-B 46-4605, JP-A 48-36281, JP-A 53-133428, JP-A 55-32070. JP, 60-239736, JP 61-169835, JP 61-169837, JP 62-58241, JP 62-212401, JP 63-70243, JP-A 63-298339, M.K. P. The compound as described in Hutt, "Journal of Heterocyclic Chemistry", 1 (No. 3) (1970) is mentioned. Of these, oxazole compounds and S-triazine compounds substituted with a trihalomethyl group are preferred.

  More preferable examples include s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring, and oxadiazole derivatives in which the oxadiazole ring is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -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- ( -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-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis ( Trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris ( Tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) Etc. -s- triazine and the following compounds.

Examples of the carbonyl compound include benzophenone, Michler ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2-dimethoxy- 2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 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, acetophenone derivatives such as 1,1,1-trichloromethyl- (p-butylphenyl) ketone, thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2- Thioxanthone derivatives such as chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate, ethyl p-diethylaminobenzoate, etc. Can be mentioned.

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

  Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butyl). Peroxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydro Peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2, -Oxanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate , Dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butyl peroxyacetate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, tert- Butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4 ′ − Tra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate), carbonyl And di (t-hexylperoxydihydrogen diphthalate).

  Examples of the metallocene compound include 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-yl, 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-penta Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoropheny -1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4 , 5,6-pentafluorophen-1-yl, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyr-1-yl) phenyl) titanium, JP-A-1-304453, Examples thereof include iron-arene complexes described in JP-A-1-152109.

Examples of the hexaarylbiimidazole compound include the specifications of JP-B-6-29285, US Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. And, 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) ) Bididazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4 ', 5,5'-
Tetraphenylbiimidazole, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′
, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like.

Examples of the organoboron compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188585, JP-A-9-188686, JP-A-9-188710, JP-A 2000-. No. 131837, Japanese Patent Application Laid-Open No. 2002-107916, Japanese Patent No. 2764769, Japanese Patent Application Laid-Open No. 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”, etc. Organic borate described, JP-A-6-157623
Organic boron sulfonium complexes or organic boron oxosulfonium complexes described in JP-A-6-175564 and JP-A-6-175561, and organic compounds described in JP-A-6-175554 and JP-A-6-175553. Boron iodonium complexes, organoboron phosphonium complexes described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-7-306527 And organic boron transition metal coordination complexes described in JP-A-7-292014.

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

  Examples of the oxime ester compound include JCS Perkin II (1979) 1653-1660), JCSPerkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, and JP-A 2000-66385. And compounds described in JP 2000-80068 A. Specific examples include compounds represented by the following structural formula.

  Examples of the onium salt compound include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055, 4,069,056, phosphonium salts described in European Patent Nos. 104,143, U.S. Pat. Nos. 339,049, 410,201,580, , 604,581 specification, J. 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. CuringASIA, p478 Tokyo, Oct (1988) and onium salts such as arsonium salts.

  In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.

The onium salts preferably used in the present invention are represented by the following general formulas (RI-I) to (RI-II).
An onium salt represented by I).

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

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

In the formula (RI-III), R ₃₁ , R ₃₂ and R ₃₃ are each independently an aryl group, alkyl group, alkenyl group or alkynyl having 20 or less carbon atoms, which may have 1 to 6 substituents. Represents a group. Among them, an aryl group is preferable from the viewpoint of reactivity and stability. 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. Specific examples include halogen ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, and sulfate ions. Of these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoints of stability and reactivity. 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.

The radical polymerization initiator is not limited to the above, but particularly from the viewpoint of reactivity and stability, triazine initiators, organic halogen compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, oxime ester compounds, onium salts. Compounds are preferable, and triazine-based initiators, organic halogen compounds, metallocene compounds, hexaarylbiimidazole compounds, and onium salt compounds are more preferable.
The radical polymerization initiator is preferably added in an amount of 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content of the photosensitive layer. Can do.

(Other ingredients)
To the photosensitive layer of the polymerizable composition of the present invention, other components suitable for its use, production method and the like can be appropriately added. Hereinafter, the other components will be exemplified.

(Sensitizing dye)
The sensitizing dye used in the photosensitive layer of the present invention is appropriately selected depending on the use and the like, and is not particularly limited. For example, a compound that absorbs light of 350 to 450 nm, infrared rays, and the like. An absorbent is mentioned.

(1) Compound that absorbs light of 350 nm to 450 nm As a sensitizing dye having a maximum absorption in the wavelength range of 350 to 450 nm used in the present invention, for example, merocyanine dyes represented by the following general formula (V), Examples thereof include benzopyrans and coumarins represented by the general formula (VI), aromatic ketones represented by the following general formula (VII), anthracenes represented by the following general formula (VIII), and the like.

(In the formula, A represents an S atom or NR ₆ , R ₆ represents a monovalent non-metallic atomic group, Y represents a basic nucleus of a dye in cooperation with an adjacent A and an adjacent carbon atom. A non-metallic atomic group, X ₁ and X ₂ each independently represent a monovalent non-metallic atomic group, and X ₁ and X ₂ may combine with each other to form an acidic nucleus of the dye.)

(In the formula, = Z represents a carbonyl group, a thiocarbonyl group, an imino group or an alkylidene group represented by the partial structural formula (1 ′), and X ₁ and X ₂ have the same meanings as in the general formula (V). , R ₇ ~
R ₁₂ each independently represents a monovalent nonmetallic atomic group. )

(In the formula, Ar ₃ represents an aromatic group or a heteroaromatic group which may have a substituent, and R ₁₃ represents a monovalent non-metallic atomic group. More preferable R ₁₃ represents an aromatic group or It is a heteroaromatic group, and Ar ₃ and R ₁₃ may be bonded to each other to form a ring.)

(In the formula, X ₃ , X ₄ and R _{14 to} R ₂₁ each independently represent a monovalent non-metallic atomic group, and more preferable X ₃ and X ₄ are electron donating groups having a negative Hammett's substituent constant. .)

In the general formulas (V) to (VIII), preferred examples of the monovalent nonmetallic atomic group represented by X ₁ to X ₄ and R ₆ to R ₂₁ include a hydrogen atom, an alkyl group (for example, a methyl group, Ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group, octadecyl group, eicosyl group, isopropyl group, isobutyl group , S-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl group, 2-norbornyl group, chloromethyl group , Bromomethyl group, 2-chloroethyl group, trifluoromethyl group, methoxymethyl group, methoxy ester Toxiethyl group, allyloxymethyl group, phenoxymethyl group, methylthiomethyl group, tolylthiomethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamoyloxyethyl Group, N-phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxoethyl group, 2-oxopropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxycarbonylbutyl group, chloro Phenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, -Methyl-N- (sulfophenyl) carbamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfa Moylpropyl group, N-methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methyl Phosphonatobutyl group, tolylphosphonohexyl group, tolylphosphonatohexyl group, phosphonooxypropyl group, phosphonatoxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group P-methylbenzyl group , Cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group, etc.), aryl group ( For example, phenyl group, biphenyl group, naphthyl group, tolyl group, xylyl group, mesityl group, cumenyl group, chlorophenyl group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group , Acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group, ethoxyphenylcarbonyl Phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, phenyl group, cyanophenyl group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl group, phosphonatophenyl group, etc.), heteroaryl group (for example, thiophene, thiathrene) , Furan, pyran, isobenzofuran, chromene, xanthene, phenoxazine, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indoyl, indazole, purine, quinolidine, isoquinoline, phthalazine , Naphthyridine, quinazoline, cynoline, pteridine, carbazole, carboline, phenanthrine, acridine, perimidine, phenanthroline, phthalazine, phenalzadi , Phenoxazine, furazane, phenoxazine, etc.), alkenyl group (eg, vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 2-chloro-1-ethenyl group, etc.), alkynyl group (eg, ethynyl group) 1-propynyl group, 1-butynyl group, trimethylsilylethynyl group, etc.), halogen atom (-F, -Br, -Cl, -I), hydroxyl group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group Alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, Acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcal Vamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, arylsulfoxy group, acylthio group, acylamino group, N- Alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido group, N ′, N′-diarylureido group, N '-Alkyl-N'-arylureido group, N-alkylureido group, N-arylureido group, N'-alkyl-N-alkylureido group, N'-alkyl-N-arylureido group, N', N ' -Dialkyl-N-alkylureido groups, N ', N'-dialkyl-N-arylurees Group, N′-aryl-N-alkylureido group, N′-aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-aryl Ureido group, N′-alkyl-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl- N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group , Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-al Rucarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group , Sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfina Moyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfur group Famoyl group, N-a A reelsulfamoyl group, an N, N-diarylsulfamoyl group, an N-alkyl-N-arylsulfamoyl group, a phosphono group (—PO ₃ H ₂ ) and a conjugate base group thereof (hereinafter referred to as a phosphonate group), Dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl phosphono group (—PO ₃ (aryl) ₂ ), alkylaryl phosphono group (—PO ₃ (alkyl) (aryl)), monoalkyl phosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkylphosphonate group), monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as arylphosphonate) referred to as group), phosphonooxy group (-OPO ₃ H ₂₎ and its conjugated base group (hereinafter referred to as phosphonophenyl group , Dialkyl phosphonooxy group _{(-OPO 3 (alkyl) 2)} , diaryl phosphonooxy group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphonooxy group _{(-OPO 3 (alkyl) (aryl} )), mono Alkylphosphonooxy group (—OPO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkylphosphonateoxy group), monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base Groups (hereinafter referred to as arylphosphonatooxy groups), cyano groups, nitro groups, and the like. Among the above substituents, hydrogen atoms, alkyl groups, aryl groups, halogen atoms, alkoxy groups, and acyl groups are particularly preferred. preferable.

  Examples of the basic nucleus of the dye formed together with A adjacent to Y in the general formula (V) and the adjacent carbon atom include 5-, 6-, and 7-membered nitrogen-containing or sulfur-containing heterocycles. A 5- or 6-membered heterocyclic ring is preferable.

  Examples of nitrogen-containing heterocycles include L. G. Brooker et al. , J .; Am. Chem. Soc. 73, 5326-5358 (1951). Any of those known to constitute a basic nucleus in the merocyanine dyes described in the literature and the references can be suitably used. Specific examples include thiazoles (for example, thiazole, 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4,5- Di (p-methoxyphenylthiazole), 4- (2-thienyl) thiazole, etc.), benzothiazoles (for example, benzothiazole, 4-chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 7- Chlorobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, 5-methoxybenzo Cheer , 6-methoxybenzothiazole, 5-iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole, 5-ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-di Oxymethylenebenzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, 6-dimethylaminobenzothiazole, 5-ethoxycarbonylbenzothiazole, etc.), naphthothiazoles (for example, naphtho [1,2] thiazole, naphtho [2 , 1] thiazole, 5-methoxynaphtho [2,1] thiazole, 5-ethoxynaphtho [2,1] thiazole, 8-methoxynaphtho [1,2] thiazole, 7-methoxynaphtho [1,2] thiazole, etc.) , Chianafuteno 7 ′, 6 ′, 4,5-thiazole (for example, 4′-methoxythianaphtheno-7 ′, 6 ′, 4,5-thiazole, etc.), oxazole (for example, 4-methyloxazole, 5-methyloxazole) 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole, etc.), benzoxazoles (benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole) 5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 6-methoxybenzoxazole, 5-methoxybenzoxazole, 4-ethoxybenzoxazole, 5-chloroben Zoxazole, 6-methoxybenzoxazole, 5-hydroxybenzoxazole, 6-hydroxybenzoxazole, etc.), naphthoxazoles (eg, naphtho [1,2] oxazole, naphtho [2,1] oxazole, etc.), selenazoles ( For example, 4-methylselenazole, 4-phenylselenazole, etc.), benzoselenazoles (for example, benzoselenazole, 5-chlorobenzoselenazole, 5-methoxybenzoselenazole, 5-hydroxybenzoselenazole, tetrahydrobenzo Selenazole etc.), naphthoselenazoles (eg naphtho [1,2] selenazole, naphtho [2,1] selenazole etc.), thiazolines (eg thiazoline, 4-methylthiazoline etc.), 2-quinolines (eg Quinoline, 3- Tilquinoline, 5-methylquinoline, 7-methylquinoline, 8-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, etc.), 4 -Quinolines (eg, quinoline, 6-methoxyquinoline, 7-methylquinoline, 8-methylquinoline, etc.), 1-isoquinolines (eg, isoquinoline, 3,4-dihydroisoquinoline, etc.), 3-isoquinolines (eg, , Isoquinoline, etc.), benzimidazoles (eg, 1,3-diethylbenzimidazole, 1-ethyl-3-phenylbenzimidazole, etc.), 3,3-dialkylindolenins (eg, 3,3-dimethylindolenin, 3,3,5-trimethylindolenine, 3,3 7, - trimethyl indolenine, etc.), 2-pyridines (e.g., pyridine, 5-methyl-pyridine, etc.), 4-pyridine (for example, a pyridine, etc.) or the like.

Examples of the sulfur-containing heterocycle include a dithiol partial structure in dyes described in JP-A-3-296759.
Specific examples include benzodithiols (for example, benzodithiol, 5-t-butylbenzodithiol, 5-methylbenzodithiol, etc.), naphthodithiols (for example, naphtho [1,2] dithiol, naphtho [2,1] Dithiol etc.), dithiols (for example, 4,5-dimethyldithiols, 4-phenyldithiols, 4-methoxycarbonyldithiols, 4,5-dimethoxycarbonylbenzodithiols, 4,5-ditrifluoromethyldithiol, 4 , 5-dicyanodithiol, 4-methoxycarbonylmethyldithiol, 4-carboxymethyldithiol and the like.

  As mentioned above, for the sake of convenience, the description used in the description of the heterocyclic ring has conventionally used the name of the heterocyclic mother skeleton, but when forming the basic skeleton partial structure of the sensitizing dye, for example, in the case of the benzothiazole skeleton It is introduced in the form of an alkylidene-type substituent with one degree of unsaturation, such as a 3-substituted-2 (3H) -benzothiazolidene group.

  Among the sensitizing dyes having an absorption maximum in the wavelength range of 350 nm to 450 nm, a dye more preferable from the viewpoint of high sensitivity is a dye represented by the following general formula (IX).

(In General Formula (IX), A represents an aromatic ring or a hetero ring which may have a substituent, and X represents an oxygen atom, a sulfur atom or N- (R ₃ ). R ₁ , R ₂ and R ₃ each independently represents a hydrogen atom or a monovalent nonmetallic atomic group, and A and R ₁ and R ₂ and R ₃ are bonded to each other to form an aliphatic or aromatic ring. May be.)

General formula (IX) will be described in more detail. R ₁ , R ₂ and R ₃ are each independently a hydrogen atom or a monovalent nonmetallic atomic group, preferably a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, substituted or non-substituted It represents a substituted aryl group, a substituted or unsubstituted aromatic heterocyclic residue, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a hydroxyl group, and a halogen atom.

Preferable examples of R ₁ , R ₂ and R ₃ will be specifically described. Examples of preferable alkyl groups include linear, branched, and cyclic alkyl groups having 1 to 20 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, Butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, t-butyl group, isopentyl group, neopentyl group,
Examples thereof include a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Of these, linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 3 to 12 carbon atoms, and cyclic alkyl groups having 5 to 10 carbon atoms are more preferable.

As the substituent of the substituted alkyl group, a monovalent nonmetallic atomic group excluding hydrogen is used, and preferred examples include a halogen atom (—F, —Br, —Cl, —I), a hydroxyl group, an alkoxy group, Aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, Reelsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N'-alkylureido group, N ', N'-dialkylureido group, N'-arylureido Group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′- Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N'- Aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-ary Luureido group, N′-alkyl-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl- N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group , Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group , Alkylsul Finyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N -Alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (-PO ₃ H ₂₎ and its conjugated base group (hereinafter, phospho Referred to as bets group), dialkyl phosphono group _{(-PO 3 (alkyl) 2)} , diaryl phosphono group _{(-PO 3 (aryl) 2)} , alkyl aryl phosphono group _{(-PO 3 (alkyl) (aryl} )) , Monoalkyl phosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkyl phosphonate group), monoaryl phosphono group (—PO ₃ H (aryl)) and its conjugate base group (Hereinafter referred to as aryl phosphonate group), phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonateoxy group), dialkyl phosphonooxy group (—OPO ₃ (alkyl)) _2), diaryl phosphonooxy group (-OPO ₃ (aryl) _2), alkylaryl phosphonooxy group (-OPO ₃ alkyl) (aryl)), monoalkyl phosphonooxy group (-OPO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), monoaryl phosphonooxy group (-OPO ₃ H (Aryl)) and conjugated base groups thereof (hereinafter referred to as arylphosphonatooxy groups), cyano groups, nitro groups, aryl groups, heteroaryl groups, alkenyl groups, and alkynyl groups.

  Specific examples of the alkyl group in these substituents include the above-described alkyl groups, and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, a xylyl group, a mesityl group, and a cumenyl group. , Chlorophenyl group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylamino Phenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group, ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, phenyl group Cyanophenyl group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl phenyl group, phosphonophenyl phenyl group and the like.

As the preferred heteroaryl group as R ₁ , R ₂ and R ₃ , a monocyclic or polycyclic aromatic ring containing at least one of nitrogen, oxygen and sulfur atoms is used. Examples of particularly preferred heteroaryl groups For example, thiophene, thiathrene, furan, pyran, isobenzofuran, chromene, xanthene, phenoxazine, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indolizine, indazole, Purine, quinolidine, isoquinoline, phthalazine, naphthyridine, quinazoline, sinoline, pteridine, carbazole, carboline, phenanthrine, acridine, perimidine, phenanthrolin, phthalazine, phenalazine, phenoxazine, flaza And phenoxazine and the like. These may be further benzo-fused and may have a substituent.

Examples of preferable alkenyl groups for R ₁ , R ₂ and R ₃ include vinyl groups, 1-
A propenyl group, a 1-butenyl group, a cinnamyl group, a 2-chloro-1-ethenyl group, and the like. Examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 1-butynyl group, and a trimethylsilylethynyl group. Can be mentioned. Examples of G ₁ in the acyl group (G ₁ CO—) include hydrogen and the above alkyl groups and aryl groups. Among these substituents, even more preferred are halogen atoms (—F, —Br, —Cl, —I), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, N-alkylamino groups, N, N— Dialkylamino group, acyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, acylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, sulfo group, sulfonate group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfide Moyl group, N-alkyl-N-arylsulfamoyl group, phosphono group, phosphonate group, dialkyl phosphono group, diaryl phosphono group, monoalkyl phosphono group, alkyl phosphonate group, monoaryl phosphono group, aryl phosphine group Examples include an onato group, a phosphonooxy group, a phosphonateoxy group, an aryl group, and an alkenyl group.

  On the other hand, examples of the alkylene group in the substituted alkyl group include divalent organic residues obtained by removing any one of the hydrogen atoms on the alkyl group having 1 to 20 carbon atoms. Can include linear alkylene groups having 1 to 12 carbon atoms, branched chains having 3 to 12 carbon atoms, and cyclic alkylene groups having 5 to 10 carbon atoms.

Specific examples of preferable substituted alkyl groups as R ₁ , R ₂ and R ₃ obtained by combining the substituent and the alkylene group include chloromethyl group, bromomethyl group, 2-chloroethyl group, trifluoromethyl group, methoxy Methyl group, methoxyethoxyethyl group, allyloxymethyl group, phenoxymethyl group, methylthiomethyl group, tolylthiomethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N -Cyclohexylcarbamoyloxyethyl group, N-phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxoethyl group, 2-oxopropyl group, carboxypropyl group, methoxycarbo Nylethyl group, allyloxycarbonylbutyl group, chlorophenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl- N- (sulfophenyl) carbamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group N-methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobu Group, tolylphosphonohexyl group, tolylphosphonatohexyl group, phosphonooxypropyl group, phosphonateoxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p -Methylbenzyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group, etc. Can be mentioned.

Specific examples of preferred aryl groups as R ₁ , R ₂ and R ₃ include those in which 1 to 3 benzene rings form a condensed ring, and those in which a benzene ring and a 5-membered unsaturated ring form a condensed ring. Specific examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group. Among these, a phenyl group and a naphthyl group are more preferable. .

Specific examples of preferred substituted aryl groups as R ₁ , R _2, and R ₃ include those having a monovalent non-metallic atomic group excluding hydrogen as a substituent on the ring-forming carbon atom of the aforementioned aryl group. . Examples of preferred substituents include the alkyl groups, substituted alkyl groups, and those previously shown as substituents in the substituted alkyl group. Preferred examples of such a substituted aryl group include a biphenyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a chlorophenyl group, a bromophenyl group, a fluorophenyl group, a chloromethylphenyl group, and a trifluoromethylphenyl group. Hydroxyphenyl group, methoxyphenyl group, methoxyethoxyphenyl group, allyloxyphenyl group, phenoxyphenyl group, methylthiophenyl group, tolylthiophenyl group, ethylaminophenyl group, diethylaminophenyl group, morpholinophenyl group, acetyloxyphenyl group, Benzoyloxyphenyl group, N-cyclohexylcarbamoyloxyphenyl group, N-phenylcarbamoyloxyphenyl group, acetylaminophenyl group, N-methylbenzoylaminophenyl group, carbo Cyphenyl group, methoxycarbonylphenyl group, allyloxycarbonylphenyl group, chlorophenoxycarbonylphenyl group, carbamoylphenyl group, N-methylcarbamoylphenyl group, N, N-dipropylcarbamoylphenyl group, N- (methoxyphenyl) carbamoylphenyl group N-methyl-N- (sulfophenyl) carbamoylphenyl group, sulfophenyl group, sulfonatophenyl group, sulfamoylphenyl group, N-ethylsulfamoylphenyl group, N, N-dipropylsulfamoylphenyl group, N-tolylsulfamoylphenyl group, N-methyl-N- (phosphonophenyl) sulfamoylphenyl group, phosphonophenyl group, phosphonatophenyl group, diethylphosphonophenyl group, diphenylphosphono Enyl group, methylphosphonophenyl group, methylphosphonatophenyl group, tolylphosphonophenyl group, tolylphosphonatophenyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallylphenyl group, 2- Examples thereof include a methylpropenylphenyl group, a 2-propynylphenyl group, a 2-butynylphenyl group, and a 3-butynylphenyl group.

Next, A in the general formula (IX) will be described. A represents an aromatic ring or a hetero ring which may have a substituent. Specific examples of the aromatic ring or hetero ring which may have a substituent include R ₁ and R in the general formula (IX) similar to those described in ₂ and R ₃ can be exemplified.

  The sensitizing dye represented by the general formula (IX) of the present invention includes an acidic nucleus as shown above, an acidic nucleus having an active methylene group, a substituted or unsubstituted aromatic ring or heterocyclic ring, These can be synthesized by referring to Japanese Patent Publication No. 59-28329.

  Preferred specific examples (D1) to (D75) of the compound represented by the general formula (IX) are shown below. In addition, an isomer with a double bond connecting an acidic nucleus and a basic nucleus is not limited to either isomer.

Details of the usage, such as which structure of these sensitizing dyes are used, whether they are used alone or in combination of two or more, and how much is added, can be appropriately set in accordance with the performance design of the final photosensitive material .
For example, compatibility with the photosensitive composition layer can be enhanced by using two or more sensitizing dyes in combination. In selecting the sensitizing dye, in addition to the photosensitivity, the molar extinction coefficient at the emission wavelength of the light source used is an important factor. By using a dye having a large molar extinction coefficient, the amount of the dye added can be made relatively small, which is economical and advantageous from the viewpoint of film physical properties of the photosensitive layer when used in a lithographic printing plate precursor. is there. The photosensitivity and resolution of the photosensitive layer and the physical properties of the exposed film are greatly affected by the absorbance at the light source wavelength, and thus the addition amount of the sensitizing dye is appropriately selected in consideration of these.

  However, for example, for the purpose of curing a thick film having a thickness of 5 μm or more, the degree of curing may be increased by lower absorbance. When used as a lithographic printing plate used in a relatively thin film thickness, the addition amount of the sensitizing dye is such that the absorbance of the photosensitive layer of the present invention is in the range of 0.1 to 1.5, preferably 0.25 to 1. It is preferable to set so as to be in the range. Usually, the amount is preferably 0.05 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and most preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the total solid content of the photosensitive layer.

(2) Infrared absorber An infrared absorber is a component used in order to raise the sensitivity with respect to an infrared laser. The infrared absorber has a function of converting absorbed infrared rays into heat. The infrared absorber used in the present invention is preferably a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

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

  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, pyranyl compounds described in JP-A-59-216146, cyanine dyes described in US It is disclosed in the pentamethine thiopyrylium salt described in Japanese Patent No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds are also preferably used. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).

  Other preferable examples of the infrared absorbing dye include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and one particularly preferred example is a cyanine dye represented by the following general formula (I).

In the general formula (I), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.

（式中、Ｘａ^-は後述するＺａ^-と同義であり、Ｒ^aは、水素原子、アルキル基、アリール
基、置換又は無置換のアミノ基、ハロゲン原子より選択される置換基を表す。）

(Wherein, Xa ^- is Za described later ^- is synonymous with, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.)

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

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (I) has an anionic substituent in its structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexagonal salt, in view of storage stability of the photosensitive layer coating solution. Fluorophosphate ion and aryl sulfonate ion.

  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 , Loso pigments, nitro pigments, natural materials, 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 surface treatment methods described above are described in “Characteristics and Applications of Metal Soap” (Sachibo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

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

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

  These infrared absorbers can be added by being encapsulated in microcapsules.

As the addition amount, it is preferable to add so that the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the photosensitive layer is in the range of 0.3 to 1.3 by the reflection measurement method, more preferably, It is in the range of 0.4 to 1.2. Within this range, a uniform polymerization reaction proceeds in the depth direction of the photosensitive layer, and good film strength of the image area and adhesion to the support can be obtained.
The absorbance of the photosensitive layer can be adjusted by the amount of infrared absorber added to the photosensitive layer and the thickness of the photosensitive layer. Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, a photosensitive layer having a thickness appropriately determined in a range where the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is measured by an optical densitometer. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

(Chain transfer agent)
The photosensitive layer of the present invention can contain a chain transfer agent. Chain transfer agents contribute to sensitivity and storage stability. As the compound that acts as a chain transfer agent, for example, a compound group having SH, PH, SiH, and GeH in the molecule is used. These can donate hydrogen to low-activity radical species to generate radicals, or can be oxidized and then deprotonated to generate radicals.

In the photosensitive layer of the present invention, thiol compounds (for example, 2-mercaptobenzimidazoles, 2-mercaptobenzthiazoles, 2-mercaptobenzoxazoles, 3-
Mercaptotriazoles, 5-mercaptotetrazoles, etc.) can be preferably used as chain transfer agents.

Among these, a thiol compound represented by the following general formula (II) is particularly preferably used. By using this thiol compound as a chain transfer agent, the problem of odor and sensitivity reduction due to evaporation from the photosensitive layer and diffusion to other layers are avoided, and it has excellent storage stability and high sensitivity and high printing durability. A lithographic printing plate precursor is obtained.

In general formula (II), R represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, and A represents a 5-membered ring having a carbon atom together with an N = CN moiety Alternatively, it represents an atomic group that forms a 6-membered heterocycle, and A may further have a substituent.

  More preferably, those represented by the following general formula (IIA) or general formula (IIB) are used.

  In general formula (IIA) and formula (IIB), R represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and X represents a halogen atom, an alkoxyl group or a substituent. The alkyl group which may have or the aryl group which may have a substituent is represented.

Specific examples of the compound represented by the general formula (II) are shown below, but the present invention is not limited thereto.

  The amount of these chain transfer agents such as thiol compounds used is preferably 0.01 to 20% by mass, more preferably 0.1 to 15% by mass, based on the total solid content of the photosensitive layer. More preferably, it is 1.0-10 mass%.

(Microcapsule)
In the present invention, as a method for causing the photosensitive layer to contain the above-described photosensitive layer constituents and other constituents described later, for example, as described in JP-A Nos. 2001-277740 and 2001-277742, A part of the components can be encapsulated in microcapsules and added to the photosensitive layer. In that case, each component can be contained in any ratio in and out of the microcapsule.

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

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into said water-insoluble polymer.

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

(Surfactant)
In the present invention, it is preferable to use a surfactant in the photosensitive layer in order to promote developability and 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. Also preferred are the fluorosurfactants described in JP-A-62-170950, JP-A-62-226143 and JP-A-60-168144.

  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 photosensitive layer.

(Hydrophilic polymer)
In the present invention, a hydrophilic polymer can be contained in order to improve the developability and the dispersion stability of the microcapsules.
Examples of the hydrophilic polymer include hydroxy group, carboxyl group, carboxylate group, hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, ammonium group, Preferred are those having a hydrophilic group such as an amide group, carboxymethyl group, sulfonic acid group, and phosphoric acid group.

Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, homopolymers of hydroxybutyl methacrylate Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate Polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a 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 hydrophilic polymer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000. The hydrophilic polymer may be any of a random polymer, a block polymer, a graft polymer, and the like.
The content of the hydrophilic polymer in the photosensitive layer is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the photosensitive layer.

(Coloring agent)
In the present invention, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in 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 addition amount is preferably 0.01 to 10% by mass with respect to the total solid content of the photosensitive layer.

(Bake-out agent)
In the photosensitive layer of the present invention, a compound that changes color by an acid or a radical can be added in order to form a printout image. As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

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

  In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, 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 acid or radical is 0.01 to 15% by mass relative to the solid content of the photosensitive layer.

(Polymerization inhibitor)
The lithographic printing plate of the present invention comprises (D) a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of a compound having a polymerizable ethylenically unsaturated bond during production or storage of the lithographic printing plate. It is preferable to add. In particular, when producing a polyurethane having a crosslinkable group as described above, it is preferable to add a polymerization inhibitor also during the production of the polyurethane in order to suppress thermal polymerization of the crosslinkable group and improve storage stability.

  Suitable thermal polymerization inhibitors for the present invention include phenolic hydroxyl group-containing compounds, N-oxide compounds, piperidine-1-oxyl free radical compounds, pyrrolidine-1-oxyl free radical compounds, N-nitrosophenylhydroxylamine It is preferable that the compound is selected from the group consisting of azo dyes, diazonium compounds, and cationic dyes.

  Among them, the above-mentioned phenolic hydroxyl group-containing compound is 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), phenolic resins, and cresol resins; N-oxide compounds are 5,5 -Dimethyl-1-pyrroline-N-oxide, 4-methylmorpholine-N-oxide, pyridine-N-oxide, 4-nitropyridine N-oxide, 3-hydroxypyridine-N-oxide, picolinic acid-N-oxide, Selected from the group consisting of nicotinic acid-N-oxide and isonicotinic acid N-oxide Piperidine-1-oxyl free radical compounds are piperidine-1-oxyl free radical, 2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-oxo-2,2, 6,6-tetramethylpiperidine-1-oxyl free radical, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, 4-acetamido-2,2,6,6-tetramethyl Piperidine-1-oxyl free radical, 4-maleimido-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, and 4-phosphonoxy-2,2,6,6-tetramethylpiperidine-1-oxyl Selected from the group consisting of free radicals; pyrrolidine-1-oxyl free radical Compounds are 3-carboxyproxyl free radicals (3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl free radical); N-nitrosophenylhydroxylamines are N-nitrosophenyl A compound selected from the group consisting of hydroxylamine primary cerium salt and N-nitrosophenylhydroxylamine aluminum salt; diazonium compounds are 4-diazophenyldimethylamine hydrogen sulfate, 4-diazodiphenylamine tetrafluoro A compound selected from the group consisting of borate and hexafluorophosphate of 3-methoxy-4-diazodiphenylamine; and cationic dyes such as crystal violet, methyl violet, ethyl violet and victoria More preferably, the compound is selected from the group consisting of pure blue BOH.

Furthermore, from the viewpoint of preventing side reactions caused by polymerization inhibitors during polyurethane synthesis, it is preferable to use benzoquinone and its derivatives, more specifically 1,4-benzoquinone derivatives having 8 or more carbon atoms. , 5-Di-tert-butyl-1,4-benzoquinone, 2-tert-butyl-1,4-benzoquinone, naphthoquinone, 2,5-diphenyl-p-benzoquinone, phenyl-p-quinone, 2,3,5 , 6-Tetramethyl-1,4-. More preferred are benzoquinone and 2,5-diamilbenzoquinone.
The addition amount of the polymerization inhibitor contained in the lithographic printing plate of the present invention is preferably 0.01 to 10000 ppm, preferably 0.1 to 5000 ppm with respect to the mass after drying of the total polymerizable composition. Is more preferable, and is most preferably 0.5 to 3000 ppm.

(Higher fatty acid derivatives, etc.)
In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenamide is added to the photosensitive layer of the present invention so that it is unevenly distributed on the surface of the photosensitive layer during the drying process after coating. May be. The amount of the higher fatty acid derivative added is preferably from about 0.1 to about 10% by mass based on the total solid content of the photosensitive layer.

(Plasticizer)
The photosensitive layer of the present invention may contain a plasticizer. 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 photosensitive layer.

(Inorganic fine particles)
The photosensitive layer of the present invention may contain inorganic fine particles in order to improve the strength of the cured film in the 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 photosensitive layer, sufficiently retains the film strength of the photosensitive 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 photosensitive layer.

(Low molecular hydrophilic compound)
The photosensitive layer of the present invention can contain a hydrophilic low molecular weight compound for improving developability. Examples of hydrophilic low molecular weight compounds include water-soluble organic compounds such as glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Its salts, organic carboxylic acids such as tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, amino acids and their salts, and organic such as tetraethylammonium chloride Quaternary ammonium salts.

[Lithographic printing plate precursor]
Next, a method for producing a lithographic printing plate precursor will be described in more detail. The lithographic printing plate precursor comprises a photosensitive layer containing the polymerizable composition of the present invention and a support, and is prepared by appropriately providing a protective layer, an undercoat layer and a backcoat layer depending on the application.

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

The coating, the photosensitive layer coating amount on the support obtained after drying (solid content) may be varied according to the intended purpose, generally 0.3 to 3.0 g / m ² is preferred. Within this range, good sensitivity and good film properties of the photosensitive layer can be obtained.
Various methods can be used as a 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 hydrophilic support. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of different 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 0.1 to 0.6 mm, more preferably 0.15 to 0.4 mm, and still more preferably 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 photosensitive 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 thus cannot be specified in general. d m ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

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

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

  The hydrophilization treatment is described in the specifications of 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 the specification of No. 272.

  When using a support with insufficient surface hydrophilicity such as a polyester film as the support of the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. As the hydrophilic layer, at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A-2001-199175 A hydrophilic layer formed by coating a coating solution containing a colloid of oxide or hydroxide, or organic hydrophilicity obtained by crosslinking or pseudo-crosslinking an organic hydrophilic polymer described in JP-A-2002-79772 A hydrophilic layer having a hydrophilic matrix, a hydrophilic layer having an inorganic hydrophilic matrix obtained by sol-gel conversion comprising hydrolysis, condensation reaction of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer made of an inorganic thin film having a surface is preferred. Arbitrariness. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or a hydroxide colloid is preferable.

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

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the photosensitive 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.

[Protective layer]
In the lithographic printing plate precursor according to the invention, a protective layer (oxygen blocking layer) is preferably provided on the photosensitive layer in order to block diffusion and penetration of oxygen that hinders the polymerization reaction during exposure. The protective layer used in the present invention has an oxygen permeability A of 1.0 ≦ A ≦ 20 (mL / m ² · day) at 25 ° C. and 1 atm.
) Is preferable. When the oxygen permeability A is extremely low at less than 1.0 (mL / m ² · day), unnecessary polymerization reaction occurs at the time of production and raw storage, and unnecessary fogging and image streaking occur during image exposure. The problem that fatness arises arises. Conversely, when the oxygen permeability A exceeds 20 (mL / m ² · day) and is too high, the sensitivity is lowered. The oxygen permeability A is more preferably 1.5 ≦ A ≦ 12 (mL / m ² · day), and further preferably 2.0 ≦ A ≦ 10.0.
The range is (mL / m ² · day). In addition to the oxygen permeability described above, the properties desired for the protective layer further do not substantially inhibit the transmission of light used for exposure, have excellent adhesion to the photosensitive layer, and are easy in the development process after exposure. It is desirable that it can be removed. The device concerning such a protective layer has been conventionally made, and is described in detail in US Pat. No. 3,458,311 and JP-B-55-49729.

  As a material that can be used for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity is preferably used. Specifically, polyvinyl alcohol, vinyl alcohol / vinyl phthalate copolymer, vinyl acetate / vinyl are used. Examples include water-soluble polymers such as alcohol / vinyl phthalate copolymer, vinyl acetate / crotonic acid copolymer, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, polyacrylic acid, and polyacrylamide. Or they can be mixed. Of these, the use of polyvinyl alcohol as the main component gives the best results in terms of basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components. Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100 mol% and a polymerization repeating unit in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8 and the like, and these can be used alone or in combination. In a preferred embodiment, the content of polyvinyl alcohol in the protective layer is 20 to 95% by mass, and more preferably 30 to 90% by mass.

Moreover, well-known modified polyvinyl alcohol can also be used preferably. 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. Examples thereof include polyvinyl alcohol having various polymerization degrees having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, and the like.

  As a component used by mixing with polyvinyl alcohol, polyvinyl pyrrolidone or a modified product thereof is preferable from the viewpoint of oxygen barrier properties and development removability, and the content in the protective layer is 3.5 to 80% by mass, preferably 10 to 60%. It is 15 mass%, More preferably, it is 15-30 mass%.

  Components of the protective layer (selection of PVA, use of additives), coating amount, and the like are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of the unsubstituted vinyl alcohol unit in the protective layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. The molecular weight of the (co) polymer such as polyvinyl alcohol (PVA) can be in the range of 2000 to 10 million, preferably in the range of 20,000 to 3 million.

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers to the (co) polymer Mass% can be added.

  In addition, adhesion to the photosensitive layer and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on an oleophilic photosensitive layer, film peeling due to insufficient adhesion tends to occur, and the peeled part causes defects such as poor film hardening due to inhibition of oxygen polymerization. On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, in U.S. Patent Application No. 292,501 and U.S. Patent Application No. 44,563, an acrylic emulsion or a water-insoluble vinyl pyrrolidone-vinyl acetate copolymer is contained in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and laminating on a photosensitive layer. Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method for the protective layer is described in detail in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729.

Furthermore, the protective layer in the lithographic printing plate precursor according to the invention preferably contains an inorganic stratiform compound for the purpose of improving oxygen barrier properties and photosensitive layer surface protection.
Here, the inorganic layered compound is a particle having a thin flat plate shape. For example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any one of K, Na, and Ca, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, and 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.H ₂ O.

In the mica group, natural mica includes muscovite, soda mica, phlogopite, biotite, and sericite. As the synthetic mica, fluorine phlogopite KMg ₃ (AlSi ₃ O ₁₀
) F ₂ , Potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) Non-swelling mica such as F ₂ , and Na tetrasilicic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Swelling mica such as Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite Na or Li hectorite (Na, Li) _1/8 Mg _{2 /} 5Li _1/8 (Si ₄ O ₁₀ ) F ₂ Is mentioned. Synthetic smectites are also useful.

In the present invention, among the inorganic layered compounds, fluorine-based swellable mica, which is a synthetic inorganic layered compound, is particularly useful. That is, this swellable synthetic mica and swellable viscosity minerals such as montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, Atomic substitution is significantly greater than other viscous minerals. As a result, the lattice layer is deficient in positive charges, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers in order to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have this tendency and are useful in the present invention, and swellable synthetic mica is particularly preferably used.

  As the shape of the inorganic layered compound used in the present invention, from the viewpoint of diffusion control, the smaller the thickness, the better. The plane size is as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. Larger is better. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  As for the particle diameter of the inorganic stratiform compound used in the present invention, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When 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.

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

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

  In addition to the inorganic layered compound, known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the protective layer coating solution. 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, known additives for improving the adhesion to the photosensitive layer and the temporal stability of the coating solution may be added to the coating solution.

  The protective layer coating solution thus prepared is applied onto the photosensitive layer provided on the support and dried to form a protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. . 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 is preferably in the range of 0.05 to 10 g / m ^{2 in} terms of the coating amount after drying. When the inorganic layered compound is contained, 0.1 to 0.5 g / The range of m ² is more preferable, and when the inorganic layered compound is not contained, the range of 0.5 to 5 g / m ² is more preferable.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, it is preferable to provide an undercoat layer of a compound containing a polymerizable group on a support. When an undercoat layer is used, the photosensitive layer is provided on the undercoat layer. The undercoat layer reinforces the adhesion between the support and the photosensitive layer in the exposed area, and easily peels the photosensitive layer from the support in the unexposed area, thereby improving developability.
As the undercoat layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of description are mentioned suitably. Particularly preferable compounds include compounds having a polymerizable group such as a methacryl group or an allyl group and a support adsorbing group such as a sulfonic acid group, a phosphoric acid group, or a phosphoric acid ester. A compound having a hydrophilicity-imparting group such as an ethylene oxide group in addition to the polymerizable group and the support-adsorbing group can also be exemplified as a suitable compound.
The coating amount (solid content) of the undercoat layer is preferably 0.1 to 100 mg / m ² ,
More preferably, it is 30 mg / m ² .

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

(Image forming method)
The lithographic printing plate precursor in the present invention is image-exposed with a light source of 350 nm to 450 nm, and then is rubbed with a rubbing member in the presence of a developer having a pH of 2.0 to 6.5 by an automatic processor. The protective layer and the unexposed photosensitive layer can be removed at once to form an image on the surface of the aluminum plate support.
That is, after removing the protective layer and the non-exposed portion of the photosensitive layer at once, it can be set on a printing machine and printed immediately.
In addition, such processing in an automatic developing machine has an advantage that it is free from dealing with the development residue derived from the protective layer / photosensitive layer that occurs in the case of on-press development.

The developer used in the present invention is an aqueous solution having a pH of 2.0 to 6.5. For example, water alone or an aqueous solution containing water as a main component (containing 60% by mass or more of water) is preferable. In particular, an aqueous solution having the same composition as that of a generally known fountain solution, a surfactant (anionic, nonionic, An aqueous solution containing a cationic system or the like, or an aqueous solution containing a water-soluble polymer compound is preferable. In particular, an aqueous solution containing both a surfactant and a water-soluble polymer compound is preferable. The pH of the developer is more preferably 2.0 to 6.0, and still more preferably 2.0 to 5.0.
When an acidic to neutral developer is used, it is preferable to contain either an organic acid or an inorganic acid. By containing an organic acid or an inorganic acid, the developability can be improved during plate making, and the occurrence of stains on the non-image area of the plate-making printing plate can be suppressed.

  Examples of the anionic surfactant used in the present invention include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid salts, linear alkyl benzene sulfonic acid salts, branched alkyl benzene sulfonic acid salts, Alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfonates , Sulfated castor oil, sulfated beef tallow oil, fatty acid alkyl ester sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid compounds Glyceryl sulfate ester salt, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate ester salt, styrene -Partially saponified products of maleic anhydride copolymer, partial saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensate and the like. Among these, dialkyl sulfosuccinates, alkyl sulfate esters and alkyl naphthalene sulfonates are particularly preferably used.

  It does not specifically limit as a cationic surfactant used for this invention, A conventionally well-known thing can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

Nonionic surfactants used in the present invention include polyethylene glycol type higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkylamine ethylene. Oxide adduct, fatty acid amide ethylene oxide adduct, fat and oil ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, etc. Fatty acid ester of alcohol type glycerol, fatty acid ester of pentaerythritol, sorbitol and sorbita Fatty acid esters of fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines.
These nonionic surfactants may be used alone or in combination of two or more. In the present invention, ethylene oxide adduct of sorbitol and / or sorbitan fatty acid ester, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, polyhydric alcohol Fatty acid esters are more preferred.

Further, from the viewpoint of stable solubility or turbidity in water, the nonionic surfactant used in the developer of the present invention is HLB (Hydrophile-Lipophile).
The (Balance) value is preferably 6 or more, and more preferably 8 or more. Furthermore, the ratio of the nonionic surfactant contained in the developer is preferably 0.01 to 10% by mass, and more preferably 0.01 to 5% by mass.
Also, acetylene glycol-based and acetylene alcohol-based oxyethylene adducts, fluorine-based and silicon-based surfactants can be used in the same manner.
As the surfactant used in the developer of the present invention, a nonionic surfactant is particularly suitable from the viewpoint of foam suppression.

  Examples of the water-soluble polymer compound used in the developer of the present invention include soybean polysaccharide, modified starch, gum arabic, dextrin, fibrin derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, pullulan. , Polyvinyl alcohol and its derivatives, polyvinyl pyrrolidone, polyacrylamide and acrylamide copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, etc. It is done.

  A well-known thing can be used for the said soybean polysaccharide, for example, there exists a brand name Soya Five (made by Fuji Oil Co., Ltd.) as a commercial item, and the thing of various grades can be used. What can be preferably used is one in which the viscosity of a 10% by mass aqueous solution is in the range of 10 to 100 mPa / sec.

  As the modified starch, known ones can be used. Starch such as corn, potato, tapioca, rice, wheat is decomposed with acid or enzyme in the range of 5 to 30 glucose residues per molecule, and further in an alkali. It can be made by a method of adding oxypropylene or the like.

Two or more water-soluble polymer compounds can be used in combination. The content of the water-soluble polymer compound in the developer is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 10% by mass.

  Further, the developer of the present invention may contain an organic solvent. Examples of the organic solvent that can be contained include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (manufactured by Esso Chemical Co., Ltd.) or gasoline, kerosene, etc.), and aromatic hydrocarbons (toluene). , Xylene, etc.), halogenated hydrocarbons (methylene dichloride, ethylene dichloride, tricrene, monochlorobenzene, etc.) and polar solvents.

Polar solvents include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, propylene glycol monoethyl ether , Propylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polypropylene glycol, tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol, etc.) , (Acetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), esters (ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, methyl lactate, butyl lactate, ethylene glycol monobutyl acetate, propylene Glycol monomethyl ether acetate, diethylene glycol acetate, diethyl phthalate, butyl levulinate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.).

  If the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. If the developer contains an organic solvent, safety, ignition, From the viewpoint of property, the concentration of the solvent is preferably less than 40% by mass.

  In addition to the above, the developer of the present invention may contain a preservative, a chelate compound, an antifoaming agent, an organic acid, an inorganic acid, an inorganic salt, and the like.

  Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium salts, pyridine, Derivatives such as quinoline and guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3diol, 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used.

  Examples of chelate compounds include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, and hydroxyethylethylenediaminetriacetic acid. Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids and phosphonoalkanetricarboxylic acids. Organic amine salts are also effective in place of the sodium and potassium salts of the chelating agents.

As the antifoaming agent, a general silicon-based self-emulsifying type, emulsifying type, or nonionic surfactant having a HLB of 5 or less can be used. Silicon antifoaming agents are preferred.
Among them, emulsification dispersion type and solubilization can be used.

  Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt.

  Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like.

  The developer described above can be used as a developer and developer replenisher for the exposed negative lithographic printing plate precursor, and is preferably applied to an automatic processor described later. When developing using an automatic processor, the developing solution becomes fatigued according to the amount of processing, so the processing capability may be restored using a replenisher or a fresh developer. This replenishing method is also preferably applied to the lithographic printing plate making method of the present invention.

  The development treatment with an aqueous solution having a pH of 2.0 to 6.5 in the present invention can be preferably carried out by an automatic processor equipped with a developer supply means and a rubbing member. As an automatic processor, for example, an automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs a rubbing process while transporting a lithographic printing plate precursor after image recording, or a cylinder Examples thereof include an automatic processor described in US Pat. Nos. 5,148,746, 5,568,768 and British Patent 2,297,719, which rub the lithographic printing plate precursor after image recording set thereon while rotating a cylinder. Among these, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll that can be preferably used in the present invention can be appropriately selected in consideration of the difficulty of scratching the image area and the stiffness of the support of the lithographic printing plate precursor. As the rotating brush roll, a known one formed by planting a brush material on a plastic or metal roll can be used. For example, as described in Japanese Patent Application Laid-Open No. 58-159533, Japanese Patent Application Laid-Open No. 3-100554, or Japanese Utility Model Publication No. 62-167253, metal or plastic in which brush materials are implanted in rows. A brush roll in which the groove mold material is radially wound around a plastic or metal roll as a core without any gap can be used.
The brush material includes plastic fibers (for example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6.6 and nylon 6.10, polyacrylonitrile, poly (meth) acrylate, etc. Acrylic and polyolefin synthetic fibers such as polypropylene and polystyrene) can be used. For example, the fiber has a hair diameter of 20 to 400 μm and a hair length of 5 to 30 mm. Can be used. Furthermore, the outer diameter of the rotating brush roll is preferably 30 to 200 mm, and the peripheral speed at the tip of the brush rubbing the plate surface is preferably 0.1 to 5 m / sec.
Moreover, it is preferable to use two or more rotating brush rolls.

  The rotating direction of the rotating brush roll used in the present invention may be the same or opposite to the conveying direction of the planographic printing plate precursor of the present invention. Thus, when two or more rotating brush rolls are used, it is preferable that at least one rotating brush roll rotates in the same direction and at least one rotating brush roll rotates in the opposite direction. This further ensures the removal of the heat sensitive layer in the non-image area. Furthermore, it is also effective to swing the rotating brush roll in the direction of the rotation axis of the brush roll.

  Although the temperature of the developer can be used at any temperature, it is preferably 10 ° C to 50 ° C.

  In the present invention, the lithographic printing plate after the rubbing treatment can be optionally washed with water, dried and desensitized. In the desensitizing treatment, a known desensitizing solution can be used.

In addition, as the plate-making process of the lithographic printing plate from the lithographic printing plate precursor according to the present invention, the entire surface may be heated before exposure, during exposure, and between exposure and development, if necessary. By such heating, the image forming reaction in the photosensitive layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Further, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full post heating or full exposure. Usually, the heating before development is preferably performed under a mild condition of 150 ° C. or less. If the temperature is too high, problems such as covering up to the non-image area occur. Very strong conditions are used for heating after development. Usually, it is the range of 200-500 degreeC. If the temperature is low, sufficient image strengthening action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area occur.

The plate making process will be further described in detail.
In the present invention, as described above, the development treatment may be performed immediately after the exposure step, but a heat treatment step may be provided between the exposure step and the development step. This heat treatment has the effect of improving the printing durability and further improving the uniformity of the image curing degree within the plate surface, and the conditions can be appropriately set within the range where these effects are present. Examples of the heating means include a conventional convection oven, an IR irradiation device, an IR laser, a microwave device, a Wisconsin oven, and the like. For example, it can be carried out by holding the plate surface temperature in the range of 70 to 150 ° C. for 1 second to 5 minutes. Preferably, the temperature is 80 ° C to 140 ° C for 5 to 1 minute, more preferably 90 ° C to 130 ° C for 10 to 30 seconds. This range is preferable in that the above effect can be obtained efficiently and there is no adverse effect such as deformation of the printing plate due to heat.
In the present invention, a development processing step is performed after the above-described exposure step and preferably the heat treatment step, to obtain a lithographic printing plate. The plate setter used in the exposure process, the heat treatment means used in the heat treatment, and the developing device used in the development process are preferably connected to each other and automatically continuously processed. Specifically, it is a plate making line in which a plate setter and a developing device are coupled by a conveying means such as a conveyor. A heat treatment unit may be provided between the plate setter and the developing device, and the heating unit and the developing device may be integrated.

When the printing plate to be used is easily affected by ambient light in the work environment, it is preferable that the plate making line is shielded by a filter or a cover.
After the image formation as described above, the entire surface may be exposed with an actinic ray such as ultraviolet light to accelerate the curing of the image portion. Examples of the light source for the entire surface exposure include a carbon arc lamp, a mercury lamp, a gallium lamp, a metal halide lamp, a xenon lamp, a tungsten lamp, and various laser lights. Furthermore, in order to obtain sufficient printing durability, the overall exposure is preferably at least 10 mJ / cm ² or more, more preferably 100 mJ / cm ² or more.
Heating may be performed simultaneously with the entire surface exposure, and further improvement in printing durability is recognized by heating. Examples of the heating device include a conventional convection oven, an IR irradiation device, an IR laser, a microwave device, a Wisconsin oven, and the like. At this time, the plate surface temperature is preferably 30 ° C to 150 ° C, more preferably 35 ° C to 130 ° C, and still more preferably 40 ° C to 120 ° C.

Prior to the above development processing, the lithographic printing plate precursor is exposed through a transparent original image having a line image, a halftone dot image or the like, or imagewise exposed by laser beam scanning or the like using digital data.
A desirable wavelength of the light source is 350 nm to 450 nm, and specifically, an InGaN semiconductor laser is suitable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.
Other exposure light beams that can be used in the present invention include ultra-high pressure, high pressure, medium pressure, and low pressure mercury lamps, chemical lamps, carbon arc lamps, xenon lamps, metal halide lamps, various visible and ultraviolet laser lamps, fluorescent lamps. A lamp, a tungsten lamp, sunlight, etc. can also be used.

As available laser light sources of 350 nm to 450 nm, the following can be used.
As a gas laser, Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), He—Cd laser (
441 nm, 325 nm, 1 mW to 100 mW), as solid laser, Nd: YAG (YVO ₄ ) and SHG crystal × 2 times combination (355 nm, 5 mW to 1 W), Cr: LiSAF and SHG crystal combination (430 nm, 10 mW), As a semiconductor laser system, a KNbO ₃ ring resonator (430 nm, 30 mW), a combination of a waveguide type wavelength conversion element and AlGaAs, InGaAs semiconductor (380 nm to 450 nm, 5 mW to 100 mW), a waveguide type wavelength conversion element, AlGaInP, and an AlGaAs semiconductor the combination of (300nm~350nm, 5mW~100mW), AlGaInN ( 350nm~450nm, 5mW~30mW), other, N ₂ laser as a pulse laser (337 nm, pulse 0.1~10mJ), XeF (351nm Pulse 10~250mJ). In particular, an AlGaInN semiconductor laser (commercially available InGaN-based semiconductor laser 400 to 410 nm, 5 to 30 mW) is preferable in terms of wavelength characteristics and cost.

In addition, examples of usable lasers include infrared lasers. Although an infrared laser is not specifically limited, The solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 760-1200 nm are mentioned suitably. The output of the infrared laser is preferably 100 mW or more. In order to shorten the exposure time, it is preferable to use a multi-beam laser device.
The exposure time per pixel is preferably within 20 μsec. Moreover, it is preferable that irradiation energy amount is 10-300 mJ / cm < ² >.

Further, as the lithographic printing plate exposure apparatus of the scanning exposure method, there are an inner drum method, an outer drum method, and a flat bed method as an exposure mechanism, and a light source that can continuously oscillate among the light sources can be preferably used. . Practically, the following exposure apparatus is particularly preferable in terms of the relationship between the photosensitive material sensitivity and the plate making time.
・ Single beam to triple beam exposure equipment that uses one or more gas lasers or solid-state laser light sources so that the internal drum system produces a semiconductor laser with a total output of 20 mW or more. One or more semiconductor lasers, gas lasers or solid-state lasers are used so that the total output is 20 mW or more with a multi-beam (1 to 10) exposure device / outer drum system using one or more semiconductor lasers, gas lasers or solid-state lasers. Multi-beam (1 to 9) exposure apparatus and multi-beam (10 or more) exposure apparatus using one or more semiconductor lasers or solid-state lasers so that the total output is 20 mW or more in the external drum system. In general, laser sensitive drawing type lithographic printing plates generally use photosensitive material sensitivity X (J / cm ²
), Exposure area S (cm ² ) of photosensitive material, power q (W) of one laser light source, number of lasers n
The equation (eq 1) is established between the total exposure time t (s).

  X · S = n · q · t (eq 1)

i) In the case of the internal drum (single beam) system, the laser rotation speed f (radians / s), the sub-scanning length Lx (cm) of the photosensitive material, the resolution Z (dots / cm), and the total exposure time t (s) In general, equation (eq 2) holds.

  f · Z · t = Lx (eq 2)

ii) External drum (multi-beam) system Drum rotation speed F (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), number of beams In general, formula (eq 3) is established during (n).

  F.Z.n.t = Lx (eq 3)

iii) Flat head (multi-beam) system Polygon mirror rotation speed H (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), Equation (eq 4) is generally established between the number of beams (n).

  F.Z.n.t = Lx (eq 4)

Resolution (2560 dpi) required for the actual printing plate, plate size (A1 / B1, sub-scan length 42 inch), exposure conditions of about 20 sheets / hour and photosensitive characteristics of the planographic printing plate precursor of the present invention (photosensitive wavelength, By substituting (sensitivity: about 0.1 mJ / cm ² ) into the above formula, it is understood that a combination with a multi-beam exposure method using a laser having a total output of 20 mW or more is particularly preferable in the planographic printing plate precursor of the present invention. it can. Further, by combining operability, cost, etc., a combination with an external drum type semiconductor laser multi-beam (10 or more) exposure apparatus is most preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

<Examples 1-17, Comparative Examples 1-2>
[Preparation of lithographic printing plate precursor type I]
An aluminum plate (material JIS A1050) having a thickness of 0.3 mm was etched by being immersed in 10% by weight sodium hydroxide at 60 ° C. for 25 seconds, washed with running water, neutralized with 20% by weight nitric acid, and then washed with water. . This was subjected to an electrolytic surface roughening treatment in a 1% by mass nitric acid aqueous solution using a sinusoidal alternating waveform current at an anode time electricity of 300 coulomb / dm ² . Subsequently 1% by mass
After dipping in an aqueous solution of sodium hydroxide at 40 ° C. for 5 seconds and then in a 30% by weight sulfuric acid aqueous solution and desmutting at 60 ° C. for 40 seconds, in a 20% by weight aqueous sulfuric acid solution at a current density of 2 A / dm ² . Anodization was performed for 2 minutes so that the thickness of the anodized film was 2.7 g / m ² . Then, it processed at 20 degreeC for 10 second with 1 mass% of sodium silicate aqueous solution. The center line average roughness (Ra) of the support thus obtained was measured using a needle having a diameter of 2 μm and found to be 0.25 μm (Ra indication according to JIS B0601).

Furthermore, after applying the following undercoat liquid (1) with a bar, it was oven-dried at 80 ° C. for 10 seconds to apply a dry coating amount of 10 mg / m ² , and a support having an undercoat layer used in the following experiments. Produced.

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

A photosensitive layer coating solution 1 having the following composition was bar coated on the aluminum support provided with the undercoat layer, followed by oven drying at 70 ° C. for 60 seconds to form a photosensitive layer having a dry coating amount of 1.1 g / m ^2. A protective layer coating solution 1 having the following composition is formed on the coating layer using a bar so that the dry coating amount is 0.75 g / m ^2, and then dried at 125 ° C. for 70 seconds for protection. A layer was formed to prepare a lithographic printing plate precursor type I series.

Photosensitive layer coating solution 1
-Specific binder polymer of the present invention (exemplary compounds described in Table 1) 0.40 g
・ 0.58g of compound with ethylenically unsaturated bond
(Dipentaerythritol pentaacrylate; SR39 manufactured by Nippon Kayaku Co., Ltd.)
・ Radical polymerization initiator (I-1) 0.08g
Sensitizing dye (D-1) 0.06g
・ Chain transfer agent (S-1) 0.07 g
・ 0.40 g of ε-phthalocyanine pigment dispersion
[Pigment: 15 parts by mass, Allyl methacrylate / methacrylic acid (80/20) copolymer as a dispersant: 10 parts by mass, Cyclohexanone / methoxypropyl acetate / 1-methoxy-2-propanol = 15 parts by mass / 20 parts as a solvent Parts / 40 parts by mass]
・ Thermal polymerization inhibitor 0.01g
(N-nitrosophenylhydroxylamine aluminum salt)
・ Fluorine-based surfactant (F-1) 0.001 g
・ Polyoxyethylene-polyoxypropylene condensate 0.04g
(Asahi Denka Kogyo Co., Ltd., Pluronic L44)
・ Tetraethylammonium chloride 0.01g
・ 3.5 g of 1-methoxy-2-propanol
・ Methyl ethyl ketone 8.0g

Protective layer coating solution 1
・ Polyvinyl alcohol (saponification degree 98 mol%, polymerization degree 500) 40 g
・ Polyvinylpyrrolidone (molecular weight 50,000) 5g
・ Poly [vinyl pyrrolidone / vinyl acetate (1/1) molecular weight 70,000]
0.5g
・ Surfactant (Emalex 710; manufactured by Nippon Emulsion Co., Ltd.)
0.5g
・ 950g of water

[Exposure, development and printing]
For each lithographic printing plate precursor type I series, use a 405 nm semiconductor laser with an output of 100 mW to perform imagewise exposure with varying energy density. After the laser exposure, place the lithographic printing plate precursor in an oven within 30 seconds and blow hot air. The entire surface of the lithographic printing plate precursor was heated by spraying and kept at 110 ° C. for 15 seconds.

Thereafter, using a developing solution 1 having the following composition, development processing was performed with an automatic developing processor having a structure shown in FIG. 1 to prepare a lithographic printing plate (without heating). The pH of the developer was 4.6. The automatic processor is an automatic processor having two rotating brush rolls. As the rotating brush roll, the first brush roll and the polybutylene terephthalate fiber (hair diameter 200 μm, hair length 17 mm). Using a brush roll with an outer diameter of 90 mm implanted with 200 mm / min in the same direction as the conveying direction (peripheral speed 0.94 m / sec at the tip of the brush), the second brush roll is made of polybutylene terephthalate Using a brush roll having an outer diameter of 60 mm in which fibers (hair diameter: 200 μm, hair length: 17 mm) were planted, it was rotated 200 times per minute in the direction opposite to the conveying direction (peripheral speed of the brush tip: 0.63 m / sec). . The transportation of the lithographic printing plate precursor was carried out at various transport speeds.
The developer was showered from the spray pipe with a circulation pump and supplied to the plate surface. The tank capacity of the developer was 10 liters.

Developer 1
・ Water 100.00g
・ Benzyl alcohol 1.00g
・ Polyoxyethylene naphthyl ether (oxyethylene average number n = 13) 1.00 g
・ Dioctylsulfosuccinate sodium salt 0.50 g
・ Arabic gum 1.00g
・ Ethylene glycol 0.50g
・ Primary ammonium phosphate 0.05g
・ Citric acid 0.05g
・ Ethylenediaminetetraacetate tetrasodium salt 0.05g

Next, the planographic printing plate is attached to a printing machine SOR-M manufactured by Heidelberg, and fountain solution (E
U-3 (Fuji Film Co., Ltd. etchant) / water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) And printing was performed at a printing speed of 6000 sheets per hour.

[Evaluation]
The lithographic printing plate precursor was evaluated for developability, sensitivity, printing durability and stain resistance as follows. The results are shown in Table 1.

<Developability>
Development was carried out at various conveying speeds as described above, and the cyan density of the non-image area was measured with a Macbeth densitometer. The transport speed at which the cyan density of the non-image area was equal to the cyan density of the aluminum substrate was determined and defined as developability. The evaluation of developability is represented by the relative developability defined as follows using Comparative Example 1 as a reference (1.0). A larger relative developability value indicates higher developability and better performance.
Relative developability = (target photosensitive material transport speed) / (reference photosensitive material transport speed)

<Sensitivity>
After 100 sheets were printed as described above and it was confirmed that a printed matter having no ink stains in the non-image area was obtained, 500 sheets were printed continuously. In the total 600th printed matter, the exposure amount with no unevenness in the ink density in the image area was measured as sensitivity. Sensitivity evaluation is represented by the relative sensitivity defined as follows using Comparative Example 1 as a reference (1.0). The larger the relative sensitivity value, the higher the sensitivity and the better the performance.
Relative sensitivity = (sensitivity of standard photosensitive material / sensitivity of target photosensitive material)

<Print durability>
As the number of printed sheets was increased, the photosensitive layer was gradually worn out and the ink acceptability was lowered, so that the ink density in the printing paper was lowered. In the printing plate exposed with the same exposure amount, the printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The evaluation of printing durability is represented by the relative printing durability defined as follows using Comparative Example 1 as a reference (1.0). The larger the relative printing durability number, the higher the printing durability.
Relative printing durability = (printing durability of target photosensitive material) / (printing durability of standard photosensitive material)

<Dirty>
After printing 500 sheets as described above, non-image areas with no ink stains are “◎”, “◎” are inferior to practical use, but “○” is practical, and some stains can be seen. The problem is indicated by “△”, and the dirty one is indicated by “×”.

As shown in Table 1, it can be seen that by using the binder polymer of the present invention, it is possible to improve the developability and the printing durability compared to Comparative Examples 1 and 2 outside the scope of the present invention. . Furthermore, although it is thought that it contributes to adsorption | suction with an aluminum substrate, it was unexpected that the stain | pollution | contamination property of the lithographic printing plate using the binder polymer of this invention improved compared with a comparative example. The counter anion X of the binder polymer ^- For, halogen-based, or a carboxylic acid, but a halogeno complex anion, a halogen oxoacid anion, a borate anion, it sulfonate anion is more preferred from the viewpoint of printing durability, stain resistance I understand.

<Examples 18 to 49, Comparative Examples 3 to 4>
[Preparation of lithographic printing plate precursor type II series]
Except for changing the photosensitive layer coating solution 1 to the photosensitive layer coating solution 2 and the protective layer coating solution 1 to the protective layer coating solution 2, the same as the lithographic printing plate precursor type I series, including the undercoat coating solution formulation, is used. It was.

Photosensitive layer coating solution 2
-Specific binder polymer of the present invention (Exemplary compounds described in Table 2)
0.54g
-Compound (M-1) having an ethylenically unsaturated bond 0.48 g
・ Radical polymerization initiator (I-1) 0.08g
Sensitizing dye (D-1) 0.06g
・ Chain transfer agent (S-2) 0.07g
・ 0.40 g of ε-phthalocyanine pigment dispersion
[Pigment: 15 parts by mass, Allyl methacrylate / methacrylic acid (80/20) copolymer as a dispersant: 10 parts by mass, Cyclohexanone / methoxypropyl acetate / 1-methoxy-2-propanol = 15 parts by mass / 20 parts as a solvent Parts / 40 parts by mass]
・ Thermal polymerization inhibitor 0.01g
(N-nitrosophenylhydroxylamine aluminum salt)
・ Fluorine-based surfactant (F-1) 0.001 g
・ Polyoxyethylene-polyoxypropylene condensate 0.04g
(Asahi Denka Kogyo Co., Ltd., Pluronic L44)
・ Tetraethylammonium chloride 0.01g
・ 3.5 g of 1-methoxy-2-propanol
・ Methyl ethyl ketone 8.0g

Protective layer coating solution (2)
・ The following mica dispersion (1): 13.00 g
Polyvinyl alcohol (saponification degree 98 mol%, polymerization degree 500)
1.30g
-Sodium 2-ethylhexyl sulfosuccinate 0.20 g
-Poly (vinyl pyrrolidone / vinyl acetate (1/1)) molecular weight 70,000
0.050g
・ Surfactant (Emalex 710; manufactured by Nippon Emulsion Co., Ltd.)
0.050g
・ Water 133.00g

Preparation of Mica Dispersion (1) To 368 g of water, 32 g of synthetic mica (“Somasif ME-100” manufactured by Co-op Chemical Co., Ltd., aspect ratio: 1000 or more) was added, and the average particle size (laser scattering method) was obtained using a homogenizer. ) Disperse to 0.5 μm to obtain a mica dispersion (1).

[Exposure, development and printing]
Each of the planographic printing plate precursor type II series was exposed, developed and printed in the same manner as in Example 1 except that the developer 1 was changed to the developer 2.

Developer 2
・ Water 100.00g
・ N-lauryldimethylbetaine 10.00g
(Takemoto Yushi Co., Ltd .; Pionein C157K)
・ Polystyrenesulfonic acid 1.00g
・ Primary ammonium phosphate 0.05g
・ Citric acid 0.05g
・ Ethylenediaminetetraacetate tetrasodium salt 0.05g
Furthermore, after adjusting so that pH of a developing solution might be set to 5.0 using phosphoric acid, it was used as the developing solution 2.

[Evaluation]
The obtained lithographic printing plate was evaluated in the same manner as in Example 1. However, the standard (1.0) of developability, sensitivity, and printing durability was set to the comparative example 3. The results are shown in Table 2.

  As shown in Table 2, by using the binder polymer of the present invention, it is possible to improve developability, printing durability, and stain resistance as compared with Comparative Examples 3 and 4 outside the scope of the present invention. You can see that

<Examples 50 to 86, Comparative Examples 5 to 6>
[Preparation of lithographic printing plate type III series]
Except for changing the protective layer coating solution from the protective layer coating solution 2 to the protective layer coating solution 1, the same one as in the lithographic printing plate precursor II series was used, including the undercoat coating solution formulation.

[Exposure, development and printing]
Each of the lithographic printing plate precursor type III series precursors was exposed, developed and printed in the same manner as in Example 1 except that the developer 1 was changed to the developer 3.

Developer 3
・ Water 100.00g
・ Polyoxyethylene lauryl amino ether 10.00g
(Takemoto Yushi Co., Ltd .; Pionein D3110)
・ Polystyrenesulfonic acid 1.00g
・ Primary ammonium phosphate 0.05g
・ Citric acid 0.05g
・ Ethylenediaminetetraacetate tetrasodium salt 0.05g
Furthermore, after adjusting so that the pH of a developing solution might be set to 5.0 using phosphoric acid, it was used as the developing solution 3.

[Evaluation]
The obtained lithographic printing plate was evaluated in the same manner as in Example 1. However, the standard (1.0) of developability, sensitivity, and printing durability was set to the comparative example 5. The results are shown in Table 3.

  As shown in Table 3, by using the binder polymer of the present invention, it is possible to improve developability, printing durability, and stain resistance as compared with Comparative Examples 3 and 4 outside the scope of the present invention. You can see that

<Examples 87 to 102, Comparative Examples 7 to 8>
[Preparation of lithographic printing plate precursor IV series]
Except for changing the photosensitive layer coating solution from the photosensitive layer coating solution 2 to the photosensitive layer coating solution 3 shown below, the same one as in the lithographic printing plate precursor II series was used, including the undercoat coating solution formulation.

Photosensitive layer coating solution 3
-Specific binder polymer of the present invention (Exemplary compounds described in Table 4)
0.50g
・ 1.00 g of a compound having an ethylenically unsaturated bond
(Isocyanuric acid EO-modified triacrylate; NK ester M-315, manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ Radical polymerization initiator (I-2) 0.08g
Sensitizing dye (D-2) 0.06g
・ 0.40 g of ε-phthalocyanine pigment dispersion
[Pigment: 15 parts by mass, allyl methacrylate / methacrylic acid (80/20) copolymer as dispersant: 10 parts by mass, cyclohexanone / methoxypropyl acetate / 1-methoxy-2-propanol = 15 parts by mass / 20 parts as solvent Parts / 40 parts by mass]
・ Thermal polymerization inhibitor 0.01g
(N-nitrosophenylhydroxylamine aluminum salt)
・ Fluorine-based surfactant (F-1) 0.001 g
・ 1-methoxy-2-propanol 7.0g
・ Methyl ethyl ketone 7.0g

[Exposure, development and printing]
Each of the lithographic printing plate precursor type IV series was subjected to image exposure with a water-cooled 40 W infrared semiconductor laser-mounted Creo Trendsetter 3244VX under the conditions of an outer drum rotation speed of 210 rpm and a resolution of 2400 dpi while changing the energy density. The obtained exposed lithographic printing plate precursor was developed and printed in the same manner as in Example 1 except that the developer 1 was changed to the developer 2.

[Evaluation]
The obtained lithographic printing plate was evaluated in the same manner as in Example 1. However, the standard (1.0) of developability, sensitivity, and printing durability was set to the comparative example 7. The results are shown in Table 4.

  As shown in Table 4, by using the binder polymer of the present invention, it is possible to improve developability, printing durability, and stain resistance as compared with Comparative Examples 3 and 4 outside the scope of the present invention. You can see that

Structure of automatic processor

Explanation of symbols

1: rotating brush roll 2: receiving roll 3: transport roll 4: transport guide plate 5: spray pipe 6: pipeline 7: filter 8: plate supply table 9: plate discharge table 10: developer tank 11: circulation pump 12: plate

Claims (7)

A lithographic printing plate precursor having a photosensitive layer containing the following (A) to (C) on a support.
(A) Binder polymer having a positively charged nitrogen atom in the main chain and / or side chain (B) Compound having an ethylenically unsaturated bond (C) Radical polymerization initiator (A) The binder polymer having a positively charged nitrogen atom in the main chain and / or side chain has a group represented by any one of the following general formulas (1) to (4). The lithographic printing plate precursor described.

In the formula, R _{1 to} R ₇ each represent a monovalent substituent, and X ⁻ represents an anion. Any _{two of} R ₁ and R ₂ and R _{4 to} R ₆ may be bonded to each other to form a ring.   (A) The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the binder polymer having a positively charged nitrogen atom in the main chain and / or side chain is a (meth) acrylic resin or a urethane resin.   (A) The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the binder polymer having a positively charged nitrogen atom in the main chain and / or side chain is a urethane resin. In the general formulas (1) to (4), at least one of R ₁ and R ₂ , R ₃ , R ₄
The lithographic printing plate precursor as claimed in claim 1, wherein at least one of ˜R ₆ and R ₇ are hydrogen atoms.   The lithographic printing plate precursor as claimed in any one of claims 1 to 5, wherein the photosensitive layer further comprises (D) a sensitizing dye.   After the lithographic printing plate precursor according to any one of claims 1 to 6 is image-exposed with a laser, the unexposed portion of the photosensitive layer is removed in the presence of a developer having a pH of 2 to 6.5. An image forming method.

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