JP2011100047A - Photosensitive negative lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive negative lithographic printing plate having high sensitivity, high preservability under a high humidity condition, and high printing durability. <P>SOLUTION: The photosensitive negative lithographic printing plate includes a hydrophilic layer, a photosensitive layer containing photosensitive polymer, and an over layer at least in this order on a plastic film support. The photosensitive layer contains organic fine particles having an average particle diameter of 80% or smaller of the sum of the thicknesses of the photosensitive layer and the over layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photosensitive negative lithographic printing plate having a hydrophilic layer, a photosensitive layer containing a photosensitive polymer, and an over layer in this order on a plastic film support. In particular, the present invention relates to a photosensitive negative lithographic printing plate that can be developed with a chemical-less developer containing substantially no alkali agent.

  In recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate without outputting it on film based on digital data produced on a computer, and various types equipped with various lasers as output machines. Plate setters and photosensitive lithographic printing plates compatible with these have been actively developed. When a plastic film support is used as a support for such a photosensitive lithographic printing plate, there is an advantage that it can be stored compactly in a plate setter. However, important problems or demands that have been highlighted with the spread of the CTP method include various points related to development processing. In the normal CTP, a lithographic printing plate is exposed to a laser image, and then a non-image portion is eluted with a developer containing a strong alkali agent, and is subjected to printing through a washing step and a gumming step. However, such an alkaline developer is harmful to the human body, and sufficient care and management are required for its handling and storage. In addition, the purchase cost and the cost related to waste liquid treatment impose a great burden on the user. In addition, the pH and temperature of the alkaline developer must be managed with great care. Handling is complicated and it is always difficult to obtain reproducible results in the plate making process.

  There has been proposed a photosensitive negative lithographic printing plate that avoids the use of such an alkaline developer and can be developed with water or the like. For example, according to Japanese Patent Application Laid-Open No. 2003-215801 (Patent Document 1), a cationic water-soluble heavy layer having a hydrophilic layer on a plastic film support and having a phenyl group with a vinyl group substituted on the side chain thereon. By applying a photosensitive layer containing a polymer or a water-soluble polymer having a phenyl group with a vinyl group substituted on the side chain and a sulfonate group, and a photopolymerization initiator or acid generator, exposure and subsequent water development Thus, the unexposed portion can be removed, and an ink receptive image portion and a non-image portion of the hydrophilic layer can be formed. Japanese Patent Application Laid-Open No. 2008-265297 (Patent Document 2) discloses a polymer having a sulfonic acid group and a phenyl group having a vinyl group bonded via a heterocycle in a side chain, a photopolymerization initiator, and By providing a photocurable photosensitive layer containing a sensitizing compound on a substrate having a specific hydrophilic layer surface, a highly sensitive photosensitive negative lithographic printing plate material capable of water development is provided. Is shown. It is shown that these systems can be developed with water without using an alkaline developer, and provide a photosensitive negative lithographic printing plate that gives a high-resolution print image.

  A lithographic printing plate having a photosensitive layer containing a photosensitive polymer is generally required to have sufficient sensitivity to exposure, particularly to short-time exposure with a laser, and that the sensitivity does not change with long-term storage. . For such a demand, it is difficult to obtain a sufficient effect with only the photosensitive layer, and it is conventionally known to use an overlayer. For example, JP-A-8-286379 (Patent Document 3), JP-A-10-228109 (Patent Document 4), JP-A-2002-169272 (Patent Document 5), and the like are water-soluble on the photosensitive layer. High sensitivity can be obtained by providing a polymer overlayer so that the photosensitive layer does not come into direct contact with oxygen during exposure (reducing the inhibition of polymerization by oxygen), and it is possible to prevent a decrease in sensitivity during long-term storage. be written.

  For such an overlayer, a water-soluble polymer is usually used because it needs to be removed together with the non-image area by development processing after exposure. However, water-soluble polymers change their oxygen permeability depending on the humidity of the air, so the oxygen permeability becomes high under high humidity conditions, and as a result, sufficient sensitivity is obtained when exposed under high humidity conditions. In addition, when stored under high-humidity conditions, the sensitivity was low and it was not satisfactory.

  In addition, as a method for improving a decrease in image formability when stored for a long period of time, a method of adding an inorganic stratiform compound to an overlayer is known as disclosed in JP-A-11-30867 (Patent Document 6). Since the inorganic layered compound has low oxygen permeability regardless of humidity, storage stability under high humidity conditions is improved. However, such printing plates are directly affected by the stress applied to the plate during printing. There was a problem that it was easy to obtain sufficient printing durability. JP 2000-147780 A (Patent Document 7) discloses a lipophilic portion and a hydrophilic layer as a protective layer that can provide sufficient adhesion between the protective layer and the photosensitive layer without deteriorating oxygen barrier properties. Although there is a method of adding inorganic fine particles having a sticky portion to the overlayer, there is a problem that it is difficult to obtain sufficient printing durability.

  On the other hand, Japanese Patent Application Laid-Open No. 2002-287340 (Patent Document 8), Japanese Patent Application Laid-Open No. 2002-287350 (Patent Document 9) and the like disclose that inorganic particles or inorganic particles are added to the photosensitive layer for the purpose of blocking or improving the image quality after development. It is described that organic fine particles may be used.

JP 2003-215801 A JP 2008-265297 A JP-A-8-286379 JP 10-228109 A JP 2002-169272 A Japanese Patent Laid-Open No. 11-30867 JP 2000-147780 A JP 2002-287340 A JP 2002-287350 A

  An object of the present invention is to provide a photosensitive negative lithographic printing plate having high sensitivity, excellent storage stability under high humidity conditions, and excellent printing durability.

The present invention has been achieved by the following invention.
(1) On a plastic film support, it has at least a hydrophilic layer, a photosensitive layer having a photosensitive polymer, and an over layer in this order, and the photosensitive layer is 80% of the sum of the thickness of the photosensitive layer and the over layer. A photosensitive negative lithographic printing plate comprising organic fine particles having the following average particle diameter:
(2) The photosensitive layer has a cationic water-soluble polymer having a polymerizable double bond in the side chain or a group selected from a sulfonate group and a sulfonate group having a polymerizable double bond in the side chain. The photosensitive negative lithographic printing plate as described in (1) above, which contains a water-soluble polymer and a photopolymerization initiator or photoacid generator.

  According to the present invention, a photosensitive negative lithographic printing plate having high sensitivity, excellent storage stability under high humidity conditions, and excellent printing durability can be provided.

  The photosensitive layer of the photosensitive negative lithographic printing plate of the present invention contains organic fine particles having an average particle size of 80% or less with respect to the sum of the thicknesses of the photosensitive layer and the over layer provided on the photosensitive layer.

  Examples of the organic fine particles include polyolefin particles such as polyacryl, polyethylene, polystyrene, polypropylene, polymethyl methacrylate, and polybutyl methacrylate, halogenated polyolefin particles such as polyfluoroethylene, polychloroethylene, and polytetrafluoroethylene, nylon. And the like, polyester particles such as polybutylene terephthalate and polyethylene terephthalate, polycarbonate particles, and silicone resin particles. These organic fine particles may be used alone or in combination of two or more.

Such organic fine particles may be commercially available. For example, organic fine particles mainly composed of acrylic resin such as Chemisnow MX180, MX300, MX600, MX1000, SX350 (manufactured by Soken Chemical Co., Ltd.) or Gantz Pearl GM-0401S, GM-0801 (manufactured by Ganz Kasei Co., Ltd.) , MX-8, MX-12, MX-15, MB-20, MB-30X5, MB30X-8 (manufactured by Sekisui Plastics Co., Ltd.), and the like, BM30X- 5, organic fine particles mainly composed of polybutyl methacrylate such as BM30X-8 (manufactured by Sekisui Plastics Co., Ltd.), polystyrene such as SBX-6, SBX-8 (manufactured by Sekisui Plastics Co., Ltd.) Organic fine particles, Chemipearl V200, V300 (Mitsui Chemicals, Inc.), Lubron L-5, L-5F, L-2, LD-1E, LD Polytetrafluoroethylene resin such as 100E (manufactured by Daikin Industries), T-10P-2, T-10P-3, T-15P-2, X-15P-2, T-17P-2, T -16P-2H, T-13P-35, T-10P-4, T-10P-5, T-13P-5, FA341, FA-341-7, TE-10P-2, TE-10P-3, TX -10P-3, TE-10P-5, TA-10P-5, A-20P-1, MB-10P-1, BC-10P-2, F-713, HI-DISPER3050 (Gifu Shellac Factory) Organic particles mainly composed of polyethylene such as Tospearl 105, Tospearl 120, Tospearl 130, Tospearl 145, Tospearl 3120, Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) It can be used resin particles. There is a preferred range for the amount of organic fine particles added, preferably 0.005 to 0.2 g / m ^{2, and} more preferably 0.01 to 0.1 g / m ² .

  The average particle size of the organic fine particles added to the photosensitive layer of the present invention is 80% or less, preferably 70% or less with respect to the sum of the coating thicknesses of the photosensitive layer and the over layer. From the viewpoint of printing durability, the average particle size of the organic fine particles is preferably larger than the thickness of the photosensitive layer. The thickness of the photosensitive layer itself is preferably in the range of 0.5 to 10 μm, and more preferably in the range of 1 to 5 μm in order to greatly improve printing durability. The over layer is preferably formed in the range of 0.1 to 10 μm, and more preferably in the range of 0.5 to 5 μm.

  The photosensitive polymer contained in the photosensitive layer of the present invention is preferably a polymer containing a monomer having a polymerizable double bond as a copolymerization component. Examples of such a monomer include allyl acrylate, allyl methacrylate, and vinyl acrylate. , Vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β-phenyl vinyl acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro vinyl methacrylate, α-chloro vinyl acrylate, β-methoxy vinyl methacrylate , Β-methoxyvinyl acrylate, vinyl thioacrylate, vinyl thiomethacrylate and the like.

  As a preferable embodiment of the above polymer, a monomer having a polymerizable double bond and a water-soluble group-containing monomer (for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4- There is a copolymer having a polymerizable double bond and a water-soluble group in a side chain containing carboxystyrene, 4-sulfostyrene, acrylonitrile, etc.) as a copolymerization component. By including a water-soluble group in the polymer structure, good developability with an alkaline developer is promoted.

  As a more preferred embodiment of the copolymer, a monomer having a phenyl group substituted with a vinyl group as a monomer having a polymerizable double bond and a monomer having a carboxy group in the structure as a water-soluble group-containing monomer (for example, acrylic acid, methacrylic acid) Acid, 4-carboxystyrene, carboxyethyl acrylate, etc.) as a copolymerization component, and a copolymer having a phenyl group substituted with a vinyl group in the side chain and a carboxy group (hereinafter referred to as a carboxylic acid type polymer). . In this carboxylic acid type polymer, the carboxy group in the structure forms a salt with an alkaline substance (for example, sodium hydroxide, sodium carbonate, triethylamine, etc.) contained in the developer during the development processing, and the photopolymerizable polymer in the unexposed area. Development of the photosensitive layer is performed. Therefore, when a carboxylic acid type polymer is used, a method using an alkaline developer described later in the development process (hereinafter referred to as alkali development) is preferable, and the pH value of the alkaline developer is 10.0 or more. The monomer having a phenyl group substituted with a vinyl group is a cationic water-soluble polymer having a polymerizable double bond in the side chain described later, or a sulfonic acid group having a polymerizable double bond in the side chain. And a water-soluble polymer having a group selected from sulfonate groups is synonymous with a phenyl group substituted with a vinyl group that is preferably present in the side chain.

  Further, in the present invention, it is more preferable that the photosensitive negative lithographic printing plate can be developed by chemicalless development containing substantially no alkali agent. Such a photosensitive polymer has an ionic hydrophilic group. The photosensitive polymer having is preferably used. However, a photosensitive polymer having an ionic hydrophilic group can provide good developability in chemical-less development, but the photosensitive polymer has a sufficient printing durability than an image obtained by the carboxylic acid type polymer described above. Tends to be difficult to obtain. Therefore, the present invention can be particularly preferably used in such a system.

  A cationic water-soluble polymer having a polymerizable double bond in the side chain (hereinafter referred to as polymer A) or a polymerizable double bond in the side chain as a photosensitive polymer having an ionic hydrophilic group; And a water-soluble polymer having a group selected from a sulfonic acid group and a sulfonic acid group (hereinafter referred to as polymer B).

  The polymer A used in the present invention represents a polymer in which a polymerizable double bond is introduced into a side chain in a water-soluble polymer having a cationic group. Hereinafter, the polymer A will be described in detail.

  The cationic group in the polymer A is a group selected from organic onium groups such as an ammonium group, a sulfonium group, a phosphonium group, an iodonium group, and an oxonium group, and among these, a quaternary ammonium group is most preferable.

  The above-mentioned polymer having an organic onium group introduced therein is disclosed in JP-B-55-13020, JP-A-55-22766, JP-A-11-153589, JP-A-2000-103179, US Pat. 693,958 and US Pat. No. 5,512,418, and can be synthesized using a conventionally known chemical reaction. That is, a monomer containing a desired organic onium group is subjected to a polymerization reaction, or a trivalent N atom, a divalent S atom or a trivalent P atom introduced on a polymer chain constituting the polymer is usually used. The method of converting into an organic onium group is mentioned by the alkylation reaction. Furthermore, the nucleophilic substitution reaction between a nucleophilic reagent such as amines, sulfides and phosphines and a leaving group on the polymer chain (for example, sulfonic acid esters or halides) causes a polymer main chain or side chain to be formed. A method of introducing an organic onium group is also mentioned.

  Monomers for introducing a polymerizable double bond into the side chain of the photosensitive polymer include allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β -Phenyl vinyl acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro vinyl methacrylate, α-chloro vinyl acrylate, β-methoxy vinyl methacrylate, β-methoxy vinyl acrylate, vinyl thioacrylate, vinyl thiomethacrylate and the like.

  In the polymer A, a polymer having a phenyl group substituted with a vinyl group in the side chain, which has good adhesion between the image-formed portion after photopolymerization and the hydrophilic layer, is particularly preferable. In the present invention, the phenyl group substituted with a vinyl group is preferably introduced into the polymer via an appropriate linking group. In this case, the linking group is not particularly limited, and includes an arbitrary group, an atom, or a complex group thereof. Further, the vinyl group and the phenyl group may have a substituent. More specifically, the polymer introduced with a phenyl group substituted with a vinyl group has a group represented by the following general formula I in the side chain.

In the formula, R ₁ , R ₂ and R ₃ may be the same or different, and each is a hydrogen atom, halogen atom, carboxyl group, sulfo group, nitro group, cyano group, amide group, amino group, alkyl group. A group selected from a group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, an arylamino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, and an arylsulfonyl group The alkyl group and aryl group constituting these groups are a halogen atom, carboxyl group, sulfo group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkenyl group, hydroxy group, alkoxy group , Aryloxy group, alkylthio group, arylthio group, alkyla It may be substituted with a mino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group or the like. Among these groups, those in which R ₁ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (for example, a methyl group, an ethyl group, etc.) and R ₂ and R ₃ are hydrogen atoms are particularly preferable.

In the formula, R ₄ is hydrogen atom, halogen atom, carboxyl group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, Represents a group selected from an arylamino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group and an arylsulfonyl group. The alkyl group and aryl group constituting these groups are a halogen atom, a carboxyl group, a sulfo group. Group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkenyl group, alkynyl group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, Acyl group, alkoxycarbonyl Group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

In the formula, m ₁ represents an integer of ₁ to 4, p represents an integer of 0 or 1, and q ₁ represents an integer of ₁ to 4.

In the formula, L ₁ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent linking group consisting of an atom group selected from a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom. To express. Specific examples include groups composed of the structural units exemplified below and the heterocyclic groups shown below. These groups may be used alone or in any combination of two or more.

Examples of the heterocyclic ring constituting L ₁ include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiazole Triazole ring, indole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline And a nitrogen-containing heterocycle such as a ring and a quinoxaline ring, a furan ring, a thiophene ring, and the like. These heterocycles may have a substituent.

  When the polyvalent linking group described above has a substituent, examples of the substituent include a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkenyl group, and an alkynyl group. Group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

In any atom group constituting a linking group L _1, if it contains an organic onium group such as quaternary ammonium groups which form a cationic group therein is particularly preferably used. In the case where such an organic onium group is not contained in the linking group, it is necessary that a repeating unit having an organic onium group is separately contained in the repeating unit constituting the main chain.

  The method for introducing a phenyl group substituted with a vinyl group into the polymer is not particularly limited. For example, Japanese Patent Publication No. 49-34041, Japanese Patent Publication No. 6-105353, Japanese Unexamined Patent Publication No. 2000-181062, Japanese Unexamined Patent Publication No. 2000-2000. Any method as disclosed in JP-A-187322 and the like may be used. In these cases, when a polymer as a precursor is synthesized in advance, a repeating unit having an organic onium group is introduced in the form of a copolymer, or a polymerizable unsaturated bonding group is introduced into the precursor polymer. In form, it is necessary to form an organic onium group, such as by the method described above.

  Specific examples of monomers that can constitute the polymer A include allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, 2-dimethylaminopropylacrylamide, 3-dimethyl. Aminopropylacrylamide, 3-dimethylaminopropylmethacrylamide, 4-aminostyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, etc. Amino group-containing monomers and quaternary ammonium salts thereof, nitrogen-containing heterocyclic ring-containing monomers such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole and the quaternary ammonium salts thereof (4- Bini Benzyl) quaternary phosphonium salt monomers such as trimethylphosphonium bromide, tertiary sulfonium salt monomers such as dimethyl-2-methacryloyloxyethylsulfonium methosulfate, 2-chloromethylstyrene, 4-chloromethylstyrene, 4-bromomethylstyrene, Examples thereof include, but are not limited to, halogenated alkyl group-containing monomers such as 2-chloroethyl acrylate and 2-chloroethyl methacrylate.

  Further, the polymer A may constitute a copolymer with any other monomer, and the monomer constituting the copolymer may be water-soluble or water-insoluble. Specific examples of water-soluble monomers include acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, cinnamic acid, maleic acid monoalkyl ester, fumaric acid Carboxyl group-containing monomers such as monoalkyl esters, 4-carboxystyrene, acrylamide-N-glycolic acid and their salts, phosphoric acid group-containing monomers such as vinylphosphonic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl Acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacryl Amino group-containing monomers such as amide, 4-aminostyrene, 4-aminomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine And quaternary ammonium salts thereof, nitrogen-containing heterocycle-containing monomers such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole and N-vinylcarbazole, and quaternary ammonium salts thereof, acrylamide, methacrylamide, N, (Meth) acrylamides such as N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-isopropylmethacrylamide, diacetoneacrylamide, N-methylolacrylamide, 2-hydroxyethyl methacrylate, 2- Hydroxypropyl Examples thereof include hydroxyalkyl (meth) acrylates such as acrylate, 2-hydroxypropyl methacrylate and glycerol monomethacrylate, alkyleneoxy group-containing (meth) acrylates such as methacrylic acid, N-vinylpyrrolidone and N-vinylcaprolactam. It is not limited to. These water-soluble monomers may be used alone or in combination of any two or more.

  In addition, in order to optimize the developability in chemicalless development and improve the strength of the image area, it is also preferable to form a copolymer with any water-insoluble monomer. Styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-chloromethylstyrene, 4-methoxystyrene, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl methacrylate, n -Hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl acrylate, alkyl (meth) acrylates such as dodecyl methacrylate, aryl (meth) acrylates such as phenyl methacrylate, benzyl methacrylate, or arylalkyl (Meth) acrylates, acrylonitrile, methacrylonitrile, phenylmaleimide, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, and other vinyl ethers, methyl vinyl ether, butyl vinyl ether, etc. Other examples include various monomers such as acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, and glycidyl methacrylate. A copolymer composed of any combination of these can be used as the polymer A.

  In any atomic group constituting a linking group for bonding a phenyl group substituted with a vinyl group to the main chain, an organic onium group such as a quaternary ammonium group that forms a cationic group is included in this group Is most preferred. In this case, since the number of phenyl groups substituted with vinyl groups contained in the polymer is directly proportional to the number of organic onium groups, the phenyl groups substituted with vinyl groups contained in the polymer to improve sensitivity. Is more preferable. The unit structure of the polymer in the case where the phenyl group substituted with the vinyl group as described above is bonded to the main chain through a cationic group can be specifically represented by the following general formula II.

In the formula, A ₁ ⁺ represents an organic onium group selected from organic onium groups such as an ammonium group, a sulfonium group, a phosphonium group, an iodonium group, and an oxonium group, and n ₁ and n ₂ each represents 0 or 1. When A ₁ ⁺ is an iodonium group, n ₁ = n ₂ = 0, and when A ₁ ⁺ is a sulfonium group, n ₁ = 1 and n ₂ = 0, and A ₁ ⁺ is an ammonium group or a phosphonium group In this case, n ₁ = n ₂ = 1.

In the formula, R ₅ and R ₆ may be the same or different, and are each an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group, a benzyl group, etc.) or an aryl group (for example, These groups may be substituted, and examples of the substituent in this case include a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, Amino group, alkyl group, aryl group, alkenyl group, alkynyl group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group , Alkylsulfonyl group, arylsulfonyl group and the like. Further, R ₅ and R ₆ may be a group containing a phenyl group substituted with a vinyl group represented by the above general formula III.

In the formula, R ₇ , R ₈ and R ₉ may be the same or different and have the same meanings as R ₁ , R ₂ and R ₃ in the general formula I, respectively. Among these groups, those in which R ₇ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (for example, a methyl group, an ethyl group, etc.) and R ₈ and R ₉ are hydrogen atoms are particularly preferable. R ₁₀ has the same meaning as R ₄ in formula I. L ₂ and L ₃ are each independently an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent group consisting of an atom group selected from a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom. And specifically has the same meaning as L ₁ in formula I. m ₂ represents an integer of 0 to 4, p ₂ represents an integer of 0 or 1, and q ₂ represents an integer of 1 to 4.

In addition, a ring structure in which an N atom, an S atom, a P atom, and the like forming an organic onium group represented by A ₁ ⁺ are combined with a group arbitrarily selected from R ₅ , R _6, L ₂ , and L ₃ (For example, a pyridinium ring, 2-quinolium ring, morphonium ring, piperidinium ring, pyrrolidinium ring, tetrahydrothiophenium ring, etc.) may be formed. These ring structures are halogen atoms, carboxyl groups, sulfo groups, nitro groups, cyano groups, amide groups, amino groups, alkyl groups, aryl groups, alkenyl groups, alkynyl groups, hydroxy groups, alkoxy groups, aryloxy groups, alkylthio groups. , Arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

  In the polymer A of the present invention, in addition to the polymer having a repeating unit in which a phenyl group substituted with a vinyl group as described above is bonded to the main chain through a cationic group, the vinyl group is substituted. A polymer having a repeating unit in which the phenyl group is bonded to the main chain directly or via a linking group containing no cationic group and a repeating unit having a cationic group can also be used.

  Examples of the polymer A in the present invention are shown below, but the present invention is not limited to these examples. The numbers in the exemplified structural formulas represent the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  There exists a preferable range about the ratio for which each repeating unit which comprises the polymer A accounts in the whole polymer. As described above, when a polymerizable double bond is bonded to the main chain via a cationic group on the side chain, the repeating unit is in the range of 10% to 80% by weight of the total polymer composition. It is particularly preferred.

  In the case of a polymer comprising a repeating unit in which a polymerizable double bond is bonded directly or via a linking group containing no cationic group to a main chain and a repeating unit having a cationic group, the polymerizable double bond is It is particularly preferable that the repeating unit having a bond is in the range of 5% by mass to 50% by mass. The proportion of the repeating unit having a cationic group is preferably in the range of 30% by mass to 95% by mass, particularly preferably in the range of 50% by mass to 90% by mass.

  There is a preferred range for the molecular weight of the polymer A, the mass average molecular weight is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 10,000 to 300,000. The polymer A in this invention may be used individually by 1 type, and may mix and use arbitrary 2 or more types.

  Next, the water-soluble polymer (polymer B) having a polymerizable double bond in the side chain and having a group selected from a sulfonic acid group and a sulfonic acid group will be described in detail.

  The polymer B is a polymer in which a group selected from a polymerizable double bond and a sulfonic acid group and a sulfonate group is bonded to the main chain either directly or via an arbitrary linking group. These linking groups are not particularly limited, and include any group, atom, or a combination thereof. The group selected from a polymerizable double bond and a sulfonic acid group and a sulfonate group may be independently bonded to the main chain, or may be selected from a polymerizable double bond, a sulfonic acid group, and a sulfonate group. The groups to be bonded may share a part or all of the linking group.

  Monomers for introducing a polymerizable double bond into the side chain of the photosensitive polymer include allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β -Phenyl vinyl acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro vinyl methacrylate, α-chloro vinyl acrylate, β-methoxy vinyl methacrylate, β-methoxy vinyl acrylate, vinyl thioacrylate, vinyl thiomethacrylate and the like.

  Also in the polymer B, like the polymer A, a polymer having a phenyl group substituted with a vinyl group and having good adhesion between the image-formed portion after photopolymerization and the hydrophilic layer is particularly preferable. The phenyl group substituted with a vinyl group is preferably introduced into the polymer via an appropriate linking group. In this case, the linking group is not particularly limited, and includes an arbitrary group, an atom, or a complex group thereof. Further, the vinyl group and the phenyl group may have a substituent. Examples of the substituent include a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkoxy group, and an aryloxy group.

  More specifically, the polymer B has groups represented by the following general formulas III and IV in the side chain.

In the formula, R ₁₁ , R ₁₂ and R ₁₃ may be the same or different, and each has the same meaning as R ₁ , R ₂ and R _{3 in the} general formula I, and R ₁₄ represents the general formula I Is synonymous with R _{4 of} L ₄ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent linking group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group, specifically It is synonymous with L < ₁ > in the said general formula I. m ₃ represents an integer of 0 to 4, p ₃ represents an integer of 0 or 1, and q ₃ represents an integer of 1 to 4.

Among the groups represented by the above general formula, those in which R ₁₁ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.) and R ₁₂ and R ₁₃ are hydrogen atoms are preferred. . The linking group L ₄ preferably includes a heterocyclic ring, and q ₃ is preferably 1 or 2.

In the formula, L ₅ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent linking group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group. Specifically, it is synonymous with L ₁ in the general formula I. Further, L ₅ may share a part or all of L _{4 in} the general formula III.

In the formula, X ⁺ represents a cation having a charge necessary for neutralizing the sulfoanion. Specific examples of such cations include inorganic ions such as alkali metal ions, alkaline earth metal ions and transition metal ions (for example, sodium, potassium, calcium, magnesium, barium and zinc), organic ammonium ions (for example, ammonium, Triethylammonium, pyridinium, tetra-n-butylammonium, etc.), iodonium ions (eg, phenyliodonium, etc.), sulfonium ions (eg, triphenylsulfonium, etc.), diazonium ions, etc. Among these, alkali metal ions or organic ammonium ions are included. Particularly preferred.

  The method for introducing a phenyl group substituted with a vinyl group in the polymer is not particularly limited. However, when a monomer having a phenyl group substituted with a vinyl group is polymerized, the vinyl group also reacts to form a gel. This is not preferable because it is expected to occur. Therefore, it is particularly preferable to synthesize a precursor polymer having no phenyl group substituted with a vinyl group, and then introduce a phenyl group substituted with the vinyl group by a conventionally known polymer reaction.

  The method for introducing a group selected from a sulfonic acid group and a sulfonic acid group into the polymer is not particularly limited, and a monomer having a group selected from the sulfonic acid group and the sulfonic acid group may be copolymerized, A precursor polymer having no group selected from a sulfonic acid group and a sulfonate group is synthesized, and then a group selected from the sulfonic acid group and the sulfonate group is introduced by a conventionally known polymer reaction. Also good.

  The polymer B of the present invention may be a polymer composed only of the above-described repeating unit having a polymerizable double bond in the side chain and a repeating unit having a group selected from a sulfonic acid group and a sulfonic acid group. Alternatively, a polymer into which another repeating unit is introduced may be used as long as the effects of the present invention are not hindered. Further, it may be a copolymer with another monomer, and specific examples of such a monomer include all the water-soluble monomers and water-insoluble monomers exemplified for the polymer A. One type may be used, or two or more types may be used.

  Examples of the polymer B of the present invention are shown below, but the present invention is not limited to these examples. The numbers in the exemplified structural formulas represent the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The weight average molecular weight of the polymer B of the present invention is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 10,000 to 300,000. The polymer B in this invention may be used individually by 1 type, and may mix and use arbitrary 2 or more types.

  There is a preferred range for the solubility of the aforementioned polymers A and B of the present invention in water. That is, the polymer is preferably dissolved in an amount of 0.5 g or more with respect to 100 ml of ion-exchanged water at 25 ° C., more preferably 2.0 g or more.

  The photosensitive layer of the present invention can be used by mixing any known various binder resins in addition to the polymer A or B described above. The binder resin in this case is not particularly limited, and specifically, a polymer arbitrarily constituted from the monomers exemplified above, polyvinylphenol, phenol resin, polyhydroxybenzal, gelatin, polyvinyl alcohol, carboxymethylcellulose, etc. Cellulose resin, polyimide resin, and the like. These binder resins are preferably water-soluble, and are water-soluble binder resins using at least one or more water-soluble monomers as exemplified above, and water-soluble binder resins such as gelatin, polyvinyl alcohol, and carboxymethyl cellulose. Is preferred.

  The photosensitive layer of the photosensitive negative lithographic printing plate of the present invention preferably contains a photopolymerization initiator or a photoacid generator in combination with the above-described photosensitive polymer. As a photoinitiator used for this invention, arbitrary compounds can be used if it is a compound which can generate | occur | produce a radical by irradiation of light or an electron beam.

  Examples of the photopolymerization initiator that can be used in the present invention include (a) aromatic ketones, (b) aromatic onium compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e And ketoxime ester compounds, (f) azinium compounds, (g) active ester compounds, (h) metallocene compounds, (i) trihaloalkyl-substituted compounds, (j) organoboron compounds, and the like.

  (A) Preferred examples of aromatic ketones include compounds having a benzophenone skeleton or a thioxanthone skeleton described in “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” JPFOUASSIER, JFRABEK (1993), P. 77 to P. 177. Α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, and JP-B-47. Benzoin derivatives described in JP-A-236364, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, Benzoin ethers described in JP-A No. 62-81345 and JP-A No. 2-211452 P-di (dimethylaminobenzoyl) benzene described in JP-A-61-194062, a thio-substituted aromatic ketone described in JP-A-61-194062, an acylphosphine sulfide described in JP-B-2-9597, and JP-B-2-9596 Examples thereof include acylphosphines described in JP-A No. 63-61950, thioxanthones described in JP-B No. 63-61950, and coumarins described in JP-B No. 59-42864.

  (B) Examples of aromatic onium salts include N, P, As, Sb, Bi, O, S, Se, Te, or I aromatic onium salts. Examples of such aromatic onium salts include compounds exemplified in Japanese Patent Publication No. 52-14277, Japanese Patent Publication No. 52-14278, Japanese Patent Publication No. 52-14279, and the like.

  (C) Examples of organic peroxides include almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. For example, 3,3 ′, 4,4′-tetra (tert-butyl) Peroxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (tert-amylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (tert-hexylperoxycarbonyl) benzophenone, 3, 3 ', 4,4'-tetra (tert-octylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (cumylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra ( p-Isopropylcumylperoxycarbonyl) benzophenone, di-tert-butyldiperoxyisophthalate, etc. Tel systems are preferred.

  (D) Examples of hexaarylbiimidazole include lophine dimers described in JP-B Nos. 45-37377 and 44-86516, such as 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) bi Imidazole, 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-trifluoromethylphenyl) -4 4,4 ', 5,5'-tetraphenylbiimidazole and the like.

  (E) Examples of ketoxime esters include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2-acetoxyiminopentane- 3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutan-2-one, 2- And ethoxycarbonyloxyimino-1-phenylpropan-1-one.

  Examples of (f) azinium salt compounds include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, JP-B-46. The compound group which has NO bond as described in -42363 gazette etc. can be mentioned.

  (G) Examples of active ester compounds include imide sulfonate compounds described in JP-B-62-2223 and the like, and active sulfonates described in JP-B-63-14340, JP-A-59-174831, and the like. Can be mentioned.

  (H) Examples of metallocene compounds include JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, and JP-A-2-4705. And titanocene compounds described in JP-A-1-304453, and iron-arene complexes described in JP-A-1-152109 and the like.

  (I) Specific examples of the trihaloalkyl-substituted compound include compounds having at least one trihaloalkyl group such as a trichloromethyl group and a tribromomethyl group in the molecule. US Pat. No. 3,954,475 Specification, U.S. Pat. No. 3,987,037, U.S. Pat. No. 4,189,323, JP-A-61-151644, JP-A-63-298339, JP-A-4-69661 And trihalomethyl-s-triazine compounds described in JP-A-11-153859, JP-A-54-74728, JP-A-55-77742, JP-A-60-138539, 2-Trihalomethyl-1,3 described in JP-A-61-143748, JP-A-4-362644, JP-A-11-84649, etc. 4- oxadiazole derivatives. Moreover, the trihaloalkyl sulfonyl compound as described in Unexamined-Japanese-Patent No. 2001-290271 etc. which this trihaloalkyl group couple | bonded with the aromatic ring or the nitrogen-containing heterocyclic ring through the sulfonyl group is mentioned.

  (J) Examples of the organic boron salt compound include JP-A-8-217813, JP-A-9-106242, JP-A-9-18885, JP-A-9-188686, JP-A-9-188710. Organoboron ammonium compounds described in JP-A-6-175561, JP-A-6-175564, JP-A-6-157623, and the like. Organoboron iodonium compounds described in JP-A-6-175553, JP-A-6-175554, etc., Organoboron phosphonium compounds described in JP-A-9-188710, JP-A-6-348011, JP-A-7- 128785, JP-A-7-140589, JP-A-7-2920 4 JP, organic boron transition metal coordination complex compound described in JP-A-7-306527 Patent Publication, and the like. Examples of the counter anion described in JP-A-62-143044 and JP-A-5-194619 include cationic dyes containing an organic boron anion.

  As the photopolymerization initiator related to the present invention, an organic boron salt is particularly preferably used. More preferably, an organic boron salt and a trihaloalkyl-substituted compound (for example, an s-triazine compound, an oxadiazole derivative or a trihaloalkylsulfonyl compound as a trihaloalkyl-substituted nitrogen-containing heterocyclic compound) are used in combination.

  The organic boron anion constituting the organic boron salt is represented by the following general formula V.

In the formula, each of R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ may be the same or different, and represents an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, or a heterocyclic group. To express. Of these, it is particularly preferred that one of R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ is an alkyl group and the other substituent is an aryl group.

  In the above-mentioned organoboron anion, a cation that forms a salt is simultaneously present. Examples of the cation in this case include alkali metal ions, onium ions, and cationic sensitizing dyes. Examples of onium salts include ammonium, sulfonium, iodonium and phosphonium compounds. When a salt of an alkali metal ion or onium compound and an organic boron anion is used, photosensitivity in the wavelength range of light absorbed by the dye is imparted by adding a sensitizing dye separately. Further, when an organic boron anion is contained as a counter anion of the cationic sensitizing dye, photosensitivity is imparted according to the absorption wavelength of the sensitizing dye. However, in the latter case, it is preferable to further contain an organic boron anion as a counter anion of the alkali metal or onium salt.

  The organic boron salt used in the present invention is a salt containing the organic boron anion represented by the general formula V shown above, and alkali metal ions and onium compounds are preferably used as cations forming the salt. Particularly preferable examples of the onium salt with an organic boron anion include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

  As the photoacid generator used in the present invention, any compound can be used as long as it is a compound capable of decomposing by irradiation with light or electron beam and generating a strong acid such as hydrochloric acid or sulfonic acid or an acid such as Lewis acid. it can. Examples of photoacid generators that can be used in the present invention include (k) aromatic diazonium salt compounds, (l) p-valic acid-o-nitrobenzyl ester, benzenesulfonic acid-o-nitrobenzyl ester, o- Sulfonic acid ester derivatives such as nitrobenzyl esters, (m) 9,10-dimethoxyanthracene-2-sulfonic acid-4-nitrobenzyl ester, pyrogallol trismethanesulfonate, naphthoquinonediazide-4-sulfonic acid esters, (n) Sulfones such as dibenzylsulfone and 4-chlorophenyl-4'-methoxyphenyldisulfone, (o) phosphate ester derivatives and (p) U.S. Pat. No. 3,332,936, JP-A-2-83638, JP 11-322707 A, JP 2000-1469 A, etc. And the like sulfonyl diazomethane compounds described.

  In the present invention, a trihaloalkyl-substituted compound can be used as a photopolymerization initiator that can be used with an organic boron salt to realize higher sensitivity and higher contrast. Specifically, the trihaloalkyl-substituted compound is a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule. As a preferable example, the trihaloalkyl group is a nitrogen-containing complex. Examples of the compound bonded to the ring group include s-triazine derivatives and oxadiazole derivatives, or trihaloalkylsulfonyl compounds in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocycle via a sulfonyl group. .

  Particularly preferred examples of trihaloalkyl-substituted nitrogen-containing heterocyclic compounds and trihaloalkylsulfonyl compounds are shown below.

  The photopolymerization initiator and photoacid generator may be used alone or in any combination of two or more. Further, any photopolymerization initiator and any photoacid generator can be used in combination. The content of the photopolymerization initiator and the photoacid generator is preferably in the range of 1 to 100% by mass and more preferably in the range of 1 to 40% by mass with respect to any amount of the photosensitive polymer.

  As another preferable element constituting the photosensitive layer in the invention, a polymerizable monomer having a polymerizable unsaturated bond group in the molecule can be exemplified. The polymerizable unsaturated bond group represents an ethylenically unsaturated double bond group that can contribute to a photopolymerization reaction or a photocrosslinking reaction by the action of a photopolymerization initiator or a photoacid generator. In particular, it is preferable to use a polyfunctional polymerizable monomer having two or more polymerizable unsaturated bond groups in the molecule. Examples of such polymerizable monomers include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene. Polyfunctional acrylate monomers such as glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylol propane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc. Methacrylate monomers, as well as itaconic acid monomers, crotonic acid monomers , Maleic acid ester monomers.

  Examples of other polymerizable monomers include styrene derivatives. The styrene derivative is preferably a compound having two or more vinylphenyl groups in the molecule. For example, 1,4-divinylbenzene, 1,4-diisopropenylbenzene, 1,4-bis (4-vinylbenzyloxy) benzene, 1,2,3-tris (4-vinylbenzyloxy) benzene, 3,5-tris (4-vinylbenzyloxy) benzene, 2,2-bis [4- (4-vinylbenzyloxy) phenyl] propane, 1,1,2,2-tetrakis [4- (4-vinylbenzyl) Oxy) phenyl] ethane, α, α, α ′, α′-tetrakis [4- (4-vinylbenzyloxy)] p-xylene, 1,2-bis (4-vinylbenzylthio) ethane, 1,4- Bis (4-vinylbenzylthio) butane, bis [2- (4-vinylbenzylthio) ethyl] ether, 2,5-bis (4-vinylbenzylthio) -1,3,4-thiadiazole, , 4,6-Tris (4-vinylbenzylthio) -1,3,5-triazine, N, N-bis (4-vinylbenzyl) -N-methylamine, N, N, N ′, N′-tetrakis (4-vinylbenzyl) -1,2-diaminoethane, N, N, N ′, N′-tetrakis (4-vinylbenzyl) p-phenylenediamine, maleic acid bis (4-vinylbenzyl) ester and the like. .

  Alternatively, a polymerizable oligomer having radical polymerizability can be preferably used instead of the above polymerizable monomer. For example, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate and the like can be used in the same manner as the polymerizable monomer as various oligomers into which acryloyl group and methacryloyl group are introduced.

  Among the photosensitive layers using the above-described photosensitive polymer, the photosensitive layer using the polymer B is particularly preferable because the strength of the image area is particularly excellent. When the photosensitive layer made of the polymer B is used as a lithographic printing plate, it is particularly suitable for printing on a printing machine without developing, and is a photosensitive negative type excellent in printing durability. A lithographic printing plate can be obtained.

  The photosensitive layer of the present invention preferably contains a sensitizer that has absorption in the visible light to infrared light region and sensitizes the above-described photopolymerization initiator or photoacid generator. As the sensitizer, various sensitizing dyes are preferably used. Such sensitizing dyes include cyanine, phthalocyanine, merocyanine, porphyrin, spiro compound, ferrocene, fluorene, fulgide, imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, trimethine acridine, coumarin, Examples include ketocoumarin, quinacridone, indigo, styryl, squarylium compound, pyrylium compound, thiopyrylium compound, and further EP 0,568,993, U.S. Pat. No. 4,508,811, U.S. Pat. The compounds described in 227,227, etc. can also be used.

In recent years, an output machine equipped with a blue semiconductor laser having a transmission wavelength of 400 to 430 nm has been developed. This output machine has a maximum energy amount of about several hundred μJ / cm ² , and the photosensitive material used is required to have high sensitivity. In the lithographic printing plate of the present invention, a lithographic printing plate corresponding to this output machine can be used by combining the following sensitizing dyes.

  As sensitizing dyes at 700 to 900 nm, cyanine, phthalocyanine, merocyanine, coumarin, porphyrin, spiro compound, ferrocene, fluorene, fulgide, imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, Coumarin, ketocoumarin, quinacridone, indigo, styryl, squarylium compound, pyrylium compound, and further, European Patent No. 0,568,993, US Pat. No. 4,508,811, US Pat. No. 5, The compounds described in 227,227 can also be used.

  Sensitizing dyes corresponding to near-infrared light in the vicinity of 700 to 900 nm are shown below.

  There is a preferable range for the content of the sensitizing dye as described above, and it is preferably added in the range of 1 to 300 mg per square meter of the photosensitive layer, and further added in the range of 5 to 200 mg per square meter of the photosensitive layer. Is particularly preferred.

  The photosensitive layer of the negative photosensitive lithographic printing plate of the present invention is also preferably added with other components for various purposes in addition to the components described above. In particular, it is preferable to add various polymerization inhibitors for the purpose of preventing thermal polymerization or thermal crosslinking of the polymerizable unsaturated bonding group and improving the long-term storage stability. As the polymerization inhibitor in this case, compounds having various phenolic hydroxyl groups such as hydroquinones, catechols, naphthols, and cresols, quinone compounds, and the like are preferably used, and hydroquinone is particularly preferably used. In this case, the polymerization inhibitor is preferably added in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the photosensitive polymer.

  As other elements, a colorant can also be preferably added. As the colorant, it is used for the purpose of enhancing the visibility of the image area after exposure and development processing, such as carbon black, phthalocyanine dye, triarylmethane dye, anthraquinone dye, azo dye, etc. Various dyes and pigments can be used, and it is preferably used in the range of 0.005 parts by mass to 0.5 parts by mass with respect to 1 part by mass of the photosensitive polymer.

  When the photosensitive layer is applied, it is prepared by applying and drying a coating liquid of a composition composed of the above-described elements on the hydrophilic layer. Various known methods can be used as the coating method, and examples thereof include bar coater coating, curtain coating, blade coating, air knife coating, roll coating, spin coating, and dip coating.

As the water-soluble polymer contained in the overlayer used in the present invention, a water-soluble polymer that blocks oxygen is preferable, and a water-soluble vinyl polymer is a typical example, and among them, polyvinyl alcohol is preferably used. In particular, it is preferable to use completely saponified polyvinyl alcohol from the viewpoints of sensitivity and storage stability, and the sensitivity can be increased to several tens of μJ / cm ² .

  As the overlayer of the lithographic printing plate of the present invention, in addition to the above-mentioned polymer, the photosensitive layer has good film-forming properties so as to prevent contact with air as much as possible, especially contact with oxygen as much as possible. Those that can be removed together are preferred. Examples of such compounds include water-soluble acrylic resins, polyvinyl pyrrolidone, gelatin, and gum arabic.

  The polyvinyl alcohol used for the over layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of unsubstituted vinyl alcohol units necessary for the development of the required water solubility. . Similarly, a part may contain other copolymerization components. Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100% and a polymerization degree 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-405, PVA-420, PVA- 613 etc. are mentioned. Examples of the copolymer include 88-100% hydrolyzed polyvinyl acetate chloroacetate or propionate, polyvinyl formal, polyvinyl acetal, and copolymers thereof.

  Water is preferable as a solvent used when the over layer is applied, but alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone may be mixed with water. The solid content concentration in the coating solution is suitably 1 to 20% by mass.

  Further, an additive such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film may be added to the over layer. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like.

  Examples of the plastic film support used as the support for the photosensitive negative planographic printing plate of the present invention include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyvinyl acetal, polycarbonate, cellulose diacetate, and cellulose triacetate. , Cellulose propionate, cellulose butyrate, cellulose nitrate and the like. The surface of these plastic film supports is subjected to various hydrophilization treatments for the purpose of improving the adhesion with the hydrophilic layer and providing water retention to the non-image area. Such hydrophilic treatment includes chemical treatment, discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, high-frequency treatment, active plasma treatment, laser treatment, and other surface treatments, and a hydrophilic subbing layer is applied to the surface. These methods may be combined and implemented. These supports may have an undercoat layer containing gelatin or polymer latex.

  The photosensitive negative lithographic printing plate of the present invention has at least a hydrophilic layer, an image forming layer, and an over layer in this order. Layer. By providing such an intermediate layer, it is possible to prevent the occurrence of scratches when handling the printing plate after the development processing, and the intermediate layer contains water during printing, so that the stress on the image area is relieved, resulting in printing durability. Is preferable because it improves more.

There is no restriction | limiting in particular in the gelatin used for the intermediate | middle layer containing gelatin, The thing extracted from a cow, a pig, a fish, etc. can be used. The coating amount of this intermediate layer is preferably 0.5 to 5 g / m ^{2, and} more preferably 1 to 3 g / m ² . If the coating amount is smaller than this, the ability to prevent printing stains due to the formation of the intermediate layer may be reduced, resulting in printing stains. If the coating amount is too large, the intermediate layer may become water during printing. Therefore, the adhesion between the image portion and the hydrophilic layer is weakened, and as a result, the printing durability may be deteriorated.

  Carbon black or a coloring pigment or titanium oxide may be added to the intermediate layer as an antihalation layer. Furthermore, the roughness of the hydrophilic layer surface can be changed by adding silica particles having an average particle size of 0.1 to 10 μm. The amount of these fine particles added is desirably 200% by mass or less based on gelatin. Further, a water-soluble polymer such as polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl pyrrolidone, carboxymethyl cellulose, etc. may be added.

  Further, the intermediate layer of the present invention preferably contains a gelatin hardener. Examples of such hardeners include gelatin hardeners such as inorganic compounds such as chromium alum and ammonium alum, aldehydes such as formalin, glyoxal, malealdehyde, succinaldehyde and glutaraldehyde, formalin and urea, and nitrogen-containing hetero N-methylols such as ethylene urea obtained by condensation with a ring, compounds having active halogen such as mucochloric acid, 2,4-dihydroxy-6-chloro-triazine salt, divinyl sulfone, divinyl ketone and N, N, N-triacylylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups in the molecule, epoxy compounds such as diethylene glycol diglycidyl ether and sorbitol polyglycidyl ether, polymer hardener age Include compounds such as dialdehyde starch, may be used alone or two or more thereof.

  The addition amount of these gelatin hardeners is preferably 1 to 30% by mass, more preferably 5 to 20% by mass with respect to gelatin.

  Next, the hydrophilic layer of the present invention will be described. Since the hydrophilic layer of the present invention contains a water-soluble polymer and a cross-linking agent, it can act as a non-image part during printing by a development process after exposure. It does not specifically limit as a water-soluble polymer, For example, polymers, such as polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, can be used. In particular, in the present invention, a non-photosensitive water-soluble polymer represented by the following general formula VI is more preferably used.

  In the above formula, X represents mass% of the repeating unit in the copolymer composition, and represents any numerical value from 1 to 40. The repeating unit A is a repeating unit having a group selected from a carboxyl group, an amino group, a hydroxyl group, and an acetoacetoxy group as a reactive group. The repeating unit B is a repeating unit having a hydrophilic group necessary for making the copolymer water-soluble.

  The water-soluble polymer represented by the general formula VI needs to contain a reactive group in the molecule so that a crosslinking reaction efficiently proceeds with a crosslinking agent described later. Such reactive groups include a carboxyl group, an amino group, a hydroxyl group, and an acetoacetoxy group. In order to obtain a water-soluble polymer having such a reactive group in the molecule, it is preferable to incorporate various monomers having a reactive group in a copolymerized form. As monomers corresponding to the repeating unit A represented by the general formula VI, acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, cinnamic acid, maleic acid Monoalkyl esters, monoalkyl esters of fumaric acid, 4-carboxystyrene, carboxyl-containing monomers such as acrylamide-N-glycolic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene, 4- Amino group-containing monomers such as minomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, 4-vinylpyridine, 2-vinyl Nitrogen-containing heterocycle-containing monomers such as pyridine and N-vinylimidazole, (meth) acrylamides such as N-methylolacrylamide and 4-hydroxyphenylacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate , Hydroxyalkyl (meth) acrylates such as 2-hydroxypropyl methacrylate and glycerol monomethacrylate, acetoacetoxy methacrylate, and the like, but are not limited to these examples.

  In the general formula VI, X, which is the ratio of the repeating unit A in the copolymer, is preferably in the range of 1 to 40, and if it is less than this range, the water resistance cannot be exhibited even if the crosslinking reaction proceeds. If this range is exceeded, the effect of introduction of the repeating unit B for imparting water solubility described below is reduced, and the affinity of the hydrophilic layer for water may be lowered, which is not preferable.

  Furthermore, as a monomer for giving the repeating unit B in the general formula VI, vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, 2-acrylamide- Sulfo group-containing monomers such as 2-methylpropanesulfonic acid and salts thereof, phosphate group-containing monomers such as vinylphosphonic acid and salts thereof, dimethyldiallylammonium chloride, 2-trimethylammonium chloride, 2-trimethylammonium chloride Ethyl methacrylate, 2-triethylammonium ethyl acrylate chloride, 2-triethylammonium ethyl methacrylate chloride, 3-trimethylammonium propylacrylamide chloride, 3-dimethylaminopropyl Pyrmethacrylamide, quaternary ammonium salts such as N, N, N-trimethyl-N- (4-vinylbenzyl) ammonium chloride, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N (Meth) acrylamides such as N, diethylacrylamide, N-isopropylmethacrylamide, methacrylic acid methoxydiethylene glycol monoester, methacrylic acid methoxypolyethylene glycol monoester, methacrylic acid polypropylene glycol monoester , N-vinyl pyrrolidone, N-vinyl caprolactam and the like, but are not limited thereto. These water-soluble monomers may be used alone to constitute the repeating unit B, or any two or more of them may be used. The example of the preferable water-soluble polymer which the hydrophilic layer of this invention contains is shown below.

  The average molecular weight of these water-soluble polymers is preferably 5,000 to 500,000, and more preferably 10,000 to 200,000. When the molecular weight is lower than this, the hydrophilic layer may dissolve or peel off when it comes into contact with water. On the other hand, if it exceeds this range, the viscosity of the coating liquid becomes high and uniform coating may not be possible.

The coating amount of these non-photosensitive water-soluble polymers is preferably 0.1 to 5 g / m ^2, more preferably 0.2 to 3 g / m ² .

  Examples of the crosslinking agent contained in the hydrophilic layer of the present invention include an epoxy compound, a compound having an oxazoline group, and a compound having an isocyanate group. The epoxy compound used in the present invention is soluble in water, methanol or ethanol, and preferably has a hydrophilic group and two or more epoxy groups in the molecule. Preferred examples of the epoxy compound are given below.

  These compounds are sold by Nagase ChemteX Corporation under the trade name “Denacol” and can be easily obtained.

  In order for the crosslinking reaction to proceed efficiently between the epoxy compound and the water-soluble polymer as described above, the reactive group contained in the water-soluble polymer is particularly preferably a carboxyl group or an amino group.

  As the oxazoline compound, a compound containing two or more groups shown below as substituents in the molecule is preferable, and various grades provided under the trade name “Epocross” from Nippon Shokubai Co., Ltd. as commercially available various compounds. These compounds are preferably used. In order for the crosslinking reaction to proceed efficiently between the oxazoline compound and the water-soluble polymer, a carboxyl group is particularly preferred as the reactive group contained in the non-photosensitive water-soluble polymer.

  As the isocyanate compound, a compound that is stable in water is preferable, and a so-called self-emulsifiable isocyanate compound or a blocked isocyanate compound is preferably used. Examples of the self-emulsifying isocyanate compound include Japanese Patent Publication No. 55-7472 (U.S. Pat. No. 3,996,154) and Japanese Patent Laid-Open No. 5-222150 (U.S. Pat. No. 5,252,696). ), Self-emulsifiable isocyanate as described in JP-A-9-71720, JP-A-9-328654, JP-A-10-60073, and the like. Specifically, for example, a polyisocyanate having an isocyanurate structure of a cyclic trimer skeleton formed from an aliphatic or alicyclic diisocyanate in a molecule, or a polyisocyanate having a burette structure, a urethane structure or the like in the molecule. A highly preferred example is a polyisocyanate compound having a structure obtained by adding a polyethylene glycol or the like having one terminal etherification to only one part of the polyisocyanate group as a base polyisocyanate. A method for synthesizing an isocyanate compound having such a structure is described in the above specification. As a specific example of such an isocyanate compound, a polyisocyanate based on cyclic trimerization using hexamethylene diisocyanate or the like as a starting material is commercially available. For example, Duranate WB40 or It is available under names such as WX1741. As the blocked isocyanate compound, for example, as seen in JP-A-4-184335 and JP-A-6-175252, it was blocked with bisulfite, alcohols, lactams, oximes, active methylenes, etc. Blocked isocyanate is preferably used. In order for the crosslinking reaction to proceed efficiently between such an isocyanate compound and a non-photosensitive water-soluble polymer, the reactive group contained in the non-photosensitive water-soluble polymer is particularly a hydroxyl group or an amino group. preferable.

  Examples of compounds that can be preferably used as hydrazide compounds are shown below. In order for the crosslinking reaction to proceed efficiently between the hydrazide compound and the water-soluble polymer, an active methylene group such as an acetoacetoxy group is particularly preferable as the reactive group contained in the water-soluble polymer.

  There is a preferred range for the ratio of the various crosslinking agents and water-soluble polymers as described above. The crosslinking agent is preferably used in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the water-soluble polymer. If the amount is less than 1 part by mass, the water resistance of the crosslinking is insufficient, and peeling of the hydrophilic layer occurs during printing. There is. On the other hand, when it is used in excess of 40 parts by mass, the affinity of the hydrophilic layer for water is lowered, which may cause soiling.

  The hydrophilic layer used in the present invention preferably contains colloidal silica in order to improve the adhesion of the image area and increase the hydrophilicity of the non-image area. The colloidal silica used in the present invention may have a spherical shape, and a chain or pearl necklace colloidal silica is also preferably used.

The colloidal silica may be composed of a simple substance of SiO ₂ , but it is also possible to use a silica whose surface is slightly modified with Al ₂ O ₃ or the like in order to change the pH dependence of the dispersibility of silica. Further, an alkaline dispersion or an acidic dispersion of colloidal silica can be selected and used depending on the pH of the coating liquid for the hydrophilic layer.

  Examples of the spherical silica include “Snowtex XS”, Snowtex S ”,“ Snowtex 20 ”,“ MP-2040 ”,“ MP-1040 ”,“ Snowtex ZL ”manufactured by Nissan Chemical Industries, Ltd. Is mentioned. These colloidal silicas have a pH of 9 or more, but when preparing an acidic coating solution, it is possible to use “Snowtex O”, “Snowtex OL”, etc., which are made by demineralizing Na ions to make them acidic. it can. Examples of the chain silica include “Snowtex UP” manufactured by Nissan Chemical Industries, Ltd., and examples of the necklace-like silica include “Snowtex PS-S” and “Snowtex PS-M”.

  The amount of colloidal silica contained in the hydrophilic layer is preferably such that the mass ratio of the water-soluble polymer of the present invention to colloidal silica is 1: 1 to 1: 4, more preferably 1: 1.5 to 1. : 3. A colloidal silica may add a single kind and may mix two or more sorts. When mixing, it is preferable that the mass ratio of the total solid content of colloidal silica and the polymer of this invention becomes the said mass ratio.

  In addition, a dye or a pigment may be added to the hydrophilic layer in order to block light other than during exposure or to prevent halation. Furthermore, by adding inorganic fine particles such as titanium oxide and silicon dioxide, irregularities can be formed on the surface, the adhesion of the image area can be improved, and the hydrophilicity of the non-image area can be improved.

  Further, in order to sufficiently crosslink the hydrophilic layer, it is stored for 12 hours to 1 week, preferably 1 day to 5 days at a temperature of 40 to 100 ° C., preferably 45 to 80 ° C. before applying the photosensitive layer. It is preferable.

  The photosensitive negative lithographic printing plate of the present invention is subjected to contact exposure or laser scanning exposure, and then a pattern is formed by removing unexposed portions with an alkaline developer or a chemicalless developer. The exposed portion is cross-linked, so that the solubility in an alkaline developer or a chemicalless developer is lowered, and an image portion is formed.

  As the plate making method of the photosensitive negative lithographic printing plate of the present invention, it is preferable to perform development with a chemicalless developer. Unlike a strong alkali developer (usually exceeding pH 10) that contains a large amount of an alkali agent that has been generally used, the chemical-less developer is substantially free of an alkali agent. Therefore, the pH of the developer used in the water development of the present invention is 10 or less, preferably pH 9.5 or less, and more preferably pH 9 or less. The lower limit of pH is about 3. Here, “substantially free of alkali agent” means that the alkali agent is 1% by mass or less, more preferably 0.1% by mass or less, based on the total mass of the developer. The developer used in the chemicalless development or water development of the present invention is such that water accounts for 70% by mass or more, more preferably 80% by mass or more of the entire developer, and other additives include ethanol, isopropanol, Various organic solvents such as n-butyl cellosolve, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and benzyl alcohol, or anionic, cationic, and nonionic surfactants can be added.

With respect to what was subjected to aqueous subbing with a subbing composition containing an epoxy compound shown in Example 4 of JP-A-60-213942 on a polyethylene terephthalate support having a thickness of 0.10 mm, The intermediate layer coating solution having the following composition was applied and dried so that the dry solid content was 3 g / m ² .

<Intermediate layer coating solution>
Gelatin (HK28 manufactured by Nippi Co., Ltd.) 3 parts by weight Water 10 parts by weight Titanium oxide 3 parts by weight Carbon black dispersion (solid content 32% by weight) 0.5 parts by weight EX851 (manufactured by Nagase ChemteX Corporation: epoxy compound) 0.3 parts by mass Surfactant 0.5 parts by mass The water was adjusted to 50 parts by mass.

Next, a hydrophilic layer coating liquid 1 having the following composition was prepared. The coating solution was applied and dried on the intermediate layer so that the dry solid content was 1.0 g / m ² . This was put into a thermostat kept at 50 ° C. for 2 days to be crosslinked.

<Hydrophilic layer coating liquid 1>
Water-soluble polymer (A-5) 2.9 parts by mass (solid content)
Cross-linking agent (E-11) 0.47 parts by mass (solid content)
Colloidal silica (PS-M manufactured by Nissan Chemical Industries, Ltd.) 6.2 parts by mass (solid content)
Ethanol 10.0 mass parts It adjusted to 100 mass parts with water.

  The pH of the hydrophilic layer coating solution 1 was adjusted to 5.0 using 1N sulfuric acid. The water-soluble polymer (A-5) used here has an average molecular weight of approximately 100,000.

A photosensitive layer coating solution A having the following composition was prepared, then applied onto the hydrophilic layer and dried at 70 ° C. for 2 minutes. The thickness of the photosensitive layer obtained by coating, the organic fine particles used and the average particle diameter thereof are shown in Table 1. In Comparative Example 4 shown in Table 1, P78A, which is a wet process silica manufactured by Mizusawa Chemical Industry Co., Ltd., was used instead of organic fine particles.
<Photosensitive layer coating liquid A>
Polymer A (CP-1 or SP-1) 3.0 parts by mass Photopolymerization initiator (BC-6) 0.5 parts by mass Photopolymerization initiator (T-9) 0.25 parts by mass Sensitizing dye (VS -8) 0.1 part by weight Blue pigment 0.1 part by weight Organic fine particles (described in Table 1) 0.3 part by weight 1,3-dioxolane 25.0 parts by weight Water 25.0 parts by weight

  Further, an overlayer coating solution having the following composition was prepared, applied on the sample coated with the photosensitive layer, and dried at 50 ° C. for 2 minutes to prepare a sample. The thickness of the over layer obtained by coating is shown in Table 1.

<Over layer>
PVA105 (manufactured by Kuraray Co., Ltd .: polyvinyl alcohol) 10 parts by weight Water 90 parts by weight Surfactant 0.5 parts by weight

  The photosensitive negative lithographic printing plates thus obtained and these were stored for one month under constant temperature and humidity conditions at 40 ° C. and 50% relative humidity and 35 ° C. and 80% relative humidity. Used for.

<Sensitivity>
Wound on the photosensitive drum, a wavelength at 405nm energy in the laser beam spot diameter 10μm to 10~250μJ / cm ^2, after the exposure by changing the exposure energy by 10μJ / cm ^2, 15 seconds 25 ° C. Water Then, the surface having the photosensitive layer was lightly rubbed with a cellulose sponge and developed. The minimum exposure amount at which an image was clearly formed at this time is shown in Table 1 as sensitivity (μJ / cm ² ).

<Residual film>
The state of the non-image area developed as described above was evaluated according to the following criteria. The results are shown in Table 1.
○: There is no remaining film at all.
Δ: There is no residual film, but the entire non-image area is lightly dyed in blue of the pigment of the photosensitive layer.
Δ ×: The entire non-image area is dyed light blue and a part of the remaining film is seen.
X: A residual film exists in the whole.

<Print durability>
The plate developed as described above was subjected to a printing test using a HAMADA 234C (Hamada Printing Co., Ltd.) offset printer. The dampening solution used was 3% Astro Mark III solution, and the ink used was BEST ONE (manufactured by T & K TOKA). In the evaluation, the number of printed sheets until a 10% flat screen image of the printed material was missing was examined every 1000 sheets, and evaluated according to the following criteria. The results are shown in Table 1.
○: 20000 or more.
Δ: 16000 or more and less than 20000
Δ ×: 12,000 or more and less than 16000.
X: Less than 12,000 sheets.

  From the results shown in Table 1, it can be seen that a photosensitive negative lithographic printing plate having high sensitivity, excellent storage stability under high humidity conditions, and excellent printing durability can be obtained by the present invention.

Claims (2)

  A plastic film support has at least a hydrophilic layer, a photosensitive layer containing a photosensitive polymer, and an over layer in this order, and the photosensitive layer is 80% or less of the sum of the thickness of the photosensitive layer and the over layer. A photosensitive negative lithographic printing plate comprising organic fine particles having an average particle diameter.   The photosensitive layer is a cationic water-soluble polymer having a polymerizable double bond in the side chain or a water-soluble polymer having a polymerizable double bond in the side chain and a group selected from a sulfonic acid group and a sulfonic acid group. The photosensitive negative lithographic printing plate according to claim 1, comprising a coalescence and a photopolymerization initiator or a photoacid generator.