JP2012159808A - Lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing plate that has excellent printing resistance, and is free from the occurrence of stains during printing.SOLUTION: A lithographic printing plate is formed by laminating a hydrophilic layer and an image forming layer in this order on a support. The hydrophilic layer contains a titanium dioxide dispersing element obtained by dispersing titanium dioxide in the presence of colloidal silica in a condition where the mixture ratio of titanium dioxide to colloidal silica is 1.5:1 to 4:1.

Description

  The present invention relates to a lithographic printing plate having a hydrophilic layer and an image forming layer in this order on a support.

  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. Furthermore, a system using a heat-sensitive hot melt layer instead of the photosensitive layer has been studied. In this system, an unprocessed plate can be handled in a bright room, and development can be performed on a printing press. it can.

  In these systems, it is necessary to previously provide a photosensitive layer or heat-sensitive layer as an image forming layer on the hydrophilic layer. Alternatively, in the heat-sensitive type, a hot-melt compound may be previously contained in the hydrophilic layer.

  In the former case, the ink receiving part is fixed by exposing the image part or heating the image part, and the other part is removed, but the hydrophilicity of the part that becomes the non-image part If the removal of the photosensitive layer or the heat-sensitive layer provided on the layer is incomplete, the hydrophilicity of the hydrophilic layer in the non-image area becomes insufficient, resulting in printing stains (background stains).

  On the contrary, if the photosensitive layer and the heat-sensitive layer are completely removed in the non-image area, the adhesion between the image area and the hydrophilic layer is weakened. As a result, the stain resistance is good, but the printing durability becomes a problem, and both the stain resistance and the printing durability are required to be improved.

  As a technique for hydrophilizing the hydrophilic layer, Japanese Patent Application Laid-Open No. 2008-265297 (Patent Document 1) contains a water-soluble polymer, a cross-linking agent that cross-links the water-soluble polymer, and colloidal silica on a support. JP-A-2009-226596 (Patent Document 2) discloses a negative photosensitive lithographic printing plate having a hydrophilic layer in which the ratio of the functional polymer and colloidal silica is specified. And a negative photosensitive lithographic printing plate containing inorganic fine particles and having a film surface pH value of the hydrophilic layer of 7.0 or more. Development with water or the like is possible with such a negative photosensitive lithographic printing plate, and although printing durability and stain resistance are improved, it is not sufficient, and further improvement has been demanded.

  As a means for improving the stain resistance of a negative photosensitive lithographic printing plate, it is conventionally known to provide an intermediate layer between a support and a hydrophilic layer. For example, JP 2010-237559 A (Patent) Document 3) discloses a negative photosensitive lithographic printing plate provided with an intermediate layer containing gelatin, urea, and a vinyl sulfone-based crosslinking agent, and JP 2010-231133 A (Patent Document 4) A negative photosensitive lithographic printing plate provided with an intermediate layer containing gelatin having a calcium ion concentration adjusted to a specific value or less is disclosed. Japanese Patent Application Laid-Open No. 2010-224188 (Patent Document 5) discloses gelatin or poly Although a negative photosensitive lithographic printing plate provided with an intermediate layer containing acrylic acid and a crosslinking agent has been disclosed, the stain resistance was not fully satisfactory.

  Further, although a method in which a hydrophilic layer contains necklace-like colloidal silica and anatase-type titanium dioxide is described in Japanese Patent Application Laid-Open No. 2001-138852 (Patent Document 6), it has good printing durability but has sufficient stain resistance. I could not get sex.

JP 2008-265297 A JP 2009-226596 A JP 2010-237559 A JP 2010-231133 A JP 2010-224188 A Japanese Patent Laid-Open No. 2001-138852

  An object of the present invention is to provide a lithographic printing plate excellent in stain resistance and printing durability.

The present invention has been achieved by the following invention.
A lithographic printing plate in which a hydrophilic layer and an image forming layer are laminated in this order on a support, a titanium dioxide dispersion in which titanium dioxide is dispersed in the presence of colloidal silica, the mixing ratio of titanium dioxide and colloidal silica A lithographic printing plate characterized in that the hydrophilic layer contains a dispersion formed by dispersing under a condition that is titanium: colloidal silica = 1.5: 1 to 4: 1.

  According to the present invention, it is possible to provide a photosensitive lithographic printing plate having excellent printing durability and improved generation of printing stains.

  The present invention will be described in detail below.

[Hydrophilic layer]
The lithographic printing plate of the present invention has a hydrophilic layer on a support. The hydrophilic layer may be a single layer or a multilayer structure including two or more layers.

  The hydrophilic layer of the present invention preferably contains a water-soluble polymer and a crosslinking agent, and the hydrophilic layer exposed by removing the image forming layer with such a structure acts as a non-image part during printing. . Such a water-soluble polymer is not particularly limited, and for example, polymers such as polyacrylic acid, polymethacrylic acid, and polyvinyl alcohol can be used. In particular, in the present invention, a non-photosensitive water-soluble polymer represented by the following general formula I 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 above general formula I needs to contain a reactive group in the molecule for allowing a crosslinking reaction to proceed efficiently 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 I, 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 above general formula I, 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 may not be exhibited even if the crosslinking reaction proceeds. If this range is exceeded, the effect of introducing the repeating unit B for imparting water solubility described below may be reduced, and the affinity of the hydrophilic layer for water may be reduced.

  Furthermore, as the monomer for giving the repeating unit B in the general formula I, 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.

These water-soluble polymers preferably have a weight average molecular weight of 5,000 to 500,000, 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 water-soluble polymers, preferably to 0.1-5 g / ^{m 2,} and 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, a compound having an isocyanate group, and a hydrazide compound. 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, for example, 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 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 Asahi Kasei Kogyo Co., Ltd. It is available under names such as WX1741. The blocked isocyanate compound is blocked with bisulfite, alcohols, lactams, oximes, active methylenes, etc. as seen in, for example, JP-A-4-184335 and JP-A-6-175252. Blocked isocyanate is preferably used. In order for the crosslinking reaction to proceed efficiently between the isocyanate compound and the water-soluble polymer, the reactive group contained in the water-soluble polymer is particularly preferably a hydroxyl group or an amino group.

  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 contrary, when it is used in excess of 40 parts by mass, the affinity of the hydrophilic layer for water is lowered, which may cause printing stains.

  The hydrophilic layer used in the present invention contains a dispersion of titanium dioxide that is dispersed in the presence of colloidal silica in order to improve the adhesiveness of the image area and to increase the hydrophilicity of the non-image area. .

  The titanium dioxide used in the present invention may have any crystal structure of anatase, rutile and brookite. In addition, either a chlorine method or a sulfuric acid method may be used as a manufacturing method. Furthermore, atoms such as aluminum and silicon may be contained. As an average particle diameter, 0.01-0.5 micrometer is preferable and 0.1-0.3 micrometer is more preferable.

  Examples of the titanium dioxide used in the present invention include chlorine-based rutile titanium dioxide such as “CR-50”, “CR-50-2”, and “CR-60” manufactured by Ishihara Sangyo Co., Ltd. "SR-1", "R-42", "R-45M" manufactured by Kogyo Co., Ltd., "R-550", "R-630", "R-660" manufactured by Ishihara Sangyo Co., Ltd. Rutile type titanium dioxide of sulfuric acid method or “A110”, “A190”, “A197” manufactured by Sakai Chemical Industry Co., Ltd., “MC-50” “MC-90” “MC” manufactured by Ishihara Sangyo Co., Ltd. Anatase type titanium dioxide such as “−150”.

  The colloidal silica added during the dispersion of titanium of the present invention may have a spherical shape or a chain shape, or a shape in which about 10 to 20 spherical particles are connected. The average particle size of the spherical colloidal silica is preferably 5 to 50 nm, and more preferably 10 to 20 nm. The mixing ratio of titanium dioxide and colloidal silica is titanium dioxide: colloidal silica = 1.5: 1 to 4: 1 as solids mass ratio, and more preferably 2.0: 1 to 3: 1.

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 alkali 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”, and “Snowtex ZL” manufactured by Nissan Chemical Industries, Ltd. Etc. 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”.

  A single kind of colloidal silica may be added, or two or more kinds may be mixed and added. When mixing, the mixing ratio of the total solid content of colloidal silica and titanium dioxide is set to the above mixing ratio.

  When preparing the titanium dioxide dispersion of the present invention, it is preferable to use water as a dispersion medium, and a solution of titanium dioxide, water and colloidal silica may be directly mixed simultaneously, or titanium dioxide is added to water. Later, colloidal silica may be added.

  The dispersion containing the titanium dioxide dispersion of the present invention is preferably dispersed using a homomixer or a homogenizer. When dispersing with a homogenizer, it is preferable to disperse at 1000-12000 rpm for 3-20 minutes.

  In the hydrophilic layer in the present invention, the amount of titanium dioxide dispersion added is preferably such that the solid content of the titanium dioxide dispersion is 25 to 70% by mass with respect to the total solid content of the hydrophilic layer. 30 to 60% by mass is more preferable. If the amount of the titanium dioxide dispersion relative to the water-soluble polymer is too small, the printing durability is deteriorated. Conversely, if the amount of the titanium dioxide dispersion is too large, the stain resistance is deteriorated.

  The hydrophilic layer in the present invention may contain silica particles having an average particle size of 3.4 to 9.0 μm and a pore volume of less than 0.62 ml / g. By adding fine particles, irregularities can be formed on the surface, the adhesion of the image area can be improved, and the printing durability can be improved.

  The hydrophilic layer of the present invention preferably contains an acrylic polyol resin. As such a resin, it is desirable to use an aqueous dispersion of an acrylic polyol resin. Examples of the water-dispersible acrylic polyol resin include resins commercially available from DIC Corporation as WE-301 and WE-300. By containing the acrylic polyol resin, excellent film strength and printing durability can be obtained. The amount of acrylic polyol resin used in the hydrophilic layer is preferably in the range of 0.1 to 0.4 parts by mass with respect to 1 part by mass of the water-soluble polymer.

  In order to sufficiently crosslink the hydrophilic layer, it should be stored at a temperature of 30 to 100 ° C., preferably 40 to 80 ° C., for 12 hours to 1 week, preferably 1 to 5 days before applying the photosensitive layer. Is preferred.

[Support]
As a support for the negative photosensitive lithographic printing plate of the present invention, paper, a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron and the like which can withstand lithographic printing can be used. The surface of the support may be coated on one or both sides with one or more polymer films or metal thin films. The surface of these supports can be surface-treated in order to improve the adhesion with the coating layer.

  Particularly preferably used supports are paper coated with a polyolefin polymer on both sides or one side, a polyester film, a polyester film whose surface is hydrophilized, an aluminum plate subjected to a surface treatment, and the like. These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. The support may be light transmissive so that backside exposure is possible. Further, the support may have an undercoat layer. In that case, for example, an aqueous undercoat composition containing an epoxy compound described in JP-A-60-213942 is exemplified.

  In the lithographic printing plate of the present invention, a hydrophilic layer and an image forming layer are coated on a support, and the image forming layer may be a photopolymerizable photosensitive layer which may be a heat-melting compound. It may be a layer. As the heat-meltable image forming layer, for example, those described in JP-A-2001-138665 may be used. Preferred examples of the photopolymerizable photosensitive layer will be described below.

[Photopolymerizable photosensitive layer]
The photosensitive polymer contained in the photosensitive layer preferable as the image forming 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, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β-phenyl vinyl acrylate, vinyl methacrylamide, vinyl acrylamide, α-chlorovinyl methacrylate, α-chlorovinyl acrylate, Examples thereof include β-methoxyvinyl 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 photosensitive layer of the present invention, it is more preferable that development by chemicalless development containing substantially no alkali agent is possible. As such a photosensitive polymer, a photosensitive polymer having an ionic hydrophilic group is used. Preferably used. However, a photosensitive polymer having an ionic hydrophilic group can provide good developability in chemicalless development, but the photosensitive polymer tends to be less oleophilic than an image obtained by the carboxylic acid type polymer described above. In particular, when the ink feed amount is increased by a printing machine so as to obtain a sufficient image density during printing, the shadow of the shadow portion is particularly likely to occur. Therefore, in such a system, it is required to impart high water retention to the hydrophilic layer, and the present invention can be used particularly suitably 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 II 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, thia 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.

  In addition, 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 esters, methyl vinyl ether, butyl vinyl ether and other vinyl ethers And other 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 when the phenyl group substituted with the vinyl group as described above is bonded to the main chain via a cationic group can be specifically represented by the following general formula III.

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, a phenyl group). , 1-naphthyl group, etc.) and these groups may be substituted, and examples of the substituent in this case include halogen atom, carboxyl group, sulfo 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, alkyl A sulfonyl group, an arylsulfonyl group, etc. are mentioned. Further, R ₅ and R ₆ may be a group containing a phenyl group substituted by a vinyl group represented by the above general formula II.

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 II, 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 II. 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 II. 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.

  Further, 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, a 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 photosensitive image forming layer 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%.

  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 weight 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 IV and V 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 II, and R ₁₄ represents the general formula II. 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 the same meaning as L ₁ in formula II. 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 II. Further, L ₅ may share part or all of L _{4 in} the general formula IV.

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 in the photosensitive image forming layer of the present invention comprises a repeating unit having a polymerizable double bond in the side chain and a repeating unit having a group selected from a sulfonate group and a sulfonate group. The polymer may be a polymer, or may be a polymer into which another repeating unit is introduced as long as the effect of the present invention is not hindered. Furthermore, 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 in the polymer A. One type may be used, or two or more types may be used.

  Examples of the polymer B in the photosensitive image forming layer 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 in the photosensitive image forming layer of the present invention 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 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 polymers A and B 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 image forming layer of the present invention may 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 lithographic printing plate comprising the photosensitive image forming layer of the present invention preferably contains a photopolymerization initiator or a photoacid generator in addition to 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 photosensitive image forming layer of the present invention include (a) aromatic ketones, (b) aromatic onium compounds, (c) organic peroxides, and (d) hexa Arylbiimidazole compounds, (e) 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 relating to the photosensitive image forming layer of 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 organoboron anion constituting the organoboron salt is represented by the following general formula VI.

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 photosensitive image forming layer of the present invention is a salt containing the organic boron anion represented by the general formula VI described above, and the cation forming the salt includes alkali metal ions and onium. Compounds are preferably used. 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.

  The photoacid generator used in the photosensitive image-forming layer of the present invention is a compound that can be decomposed by irradiation with light or electron beam to generate a strong acid such as hydrochloric acid or sulfonic acid or an acid such as a Lewis acid. Any compound can be used. 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 photosensitive image-forming layer of the present invention, a trihaloalkyl-substituted compound can be used as a photopolymerization initiator that can be further enhanced in sensitivity and contrast when used with an organic boron salt. 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 image forming layer of the present 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 press without carrying out development processing, and negative photosensitive property with excellent printing durability. A lithographic printing plate can be obtained.

  The photosensitive image-forming layer of the present invention may contain a sensitizer that has absorption in the visible light to infrared light region and sensitizes the aforementioned photopolymerization initiator or photoacid generator. preferable. 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.

  In the photosensitive image forming layer of the present invention, it is also preferable to add 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.

[Over layer]
It is preferable to provide an over layer on the photosensitive image forming layer of the present invention. The over layer preferably contains a water-soluble polymer, and as such a water-soluble polymer, 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.

  As the overlayer of the lithographic printing plate of the photosensitive image-forming layer of the present invention, in addition to the above-mentioned polymer, the photosensitive layer has good film-forming properties in order to prevent contact with air as much as possible, particularly oxygen, and development. Those which are sometimes removable together with the unexposed photosensitive layer 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.

[Plate making method]
The lithographic printing plate in the photosensitive image forming layer of the present invention is subjected to contact exposure or laser scanning exposure and then subjected to pattern formation 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 a plate making method of a lithographic printing plate in the photosensitive image forming layer of the present invention, development with a chemicalless developer is preferably performed. 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, the phrase “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.

[Preparation of negative photosensitive lithographic printing plate]

  Titanium dioxide, colloidal silica, and water were mixed as in the following composition, and dispersed with a homomixer at 8000 rpm for 10 minutes. Table 1 shows the titanium dioxide and colloidal silica used and the amounts added. In addition, titanium dioxide was added to 10 parts by mass of water without adding colloidal silica, and dispersion was performed with a homomixer. However, Aron T50 (a polyacrylic acid dispersant manufactured by Toagosei Co., Ltd.) was added. 0.1 part by mass was added and dispersed to 50 parts by mass with water to prepare a dispersion. This titanium dioxide dispersion was used in the hydrophilic layer coating liquid of Comparative Example 4.

<Dispersion containing titanium dioxide dispersion>
Titanium dioxide 10 parts by mass (solid content)
Colloidal silica A X parts by mass (solid content)
Colloidal silica BY parts by mass (solid content)
Adjusted to 50 parts by weight with water.

<Hydrophilic layer>
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 0.20 mm, The hydrophilic layer coating liquid 1 having the following composition was applied with a wire bar so that the dry solid content of the water-soluble polymer (A-5) was 0.8 g / m ² and dried using a drier. Separately, the titanium dioxide dispersion and colloidal silica used in Comparative Example 4 above were directly added to the hydrophilic layer coating liquid in the addition amounts shown in Table 1, and the same procedure was followed. The hydrophilic layer of Example 5 was obtained. Then, it warmed for 1 week in a 40 degreeC storage, and raised the bridge | crosslinking level.

<Hydrophilic layer coating solution>
Water-soluble polymer (A-5: weight average molecular weight 100,000) 1.0 part by mass (solid content)
Cross-linking agent (E-11) 0.2 parts by mass (solid content)
Titanium dioxide dispersion 2.0 parts by mass (solid content)
Silica particles 0.2 parts by mass (solid content)
(Grace Devison Silo Block S500, average particle size 5.1 μm, pore volume 0.40 ml / g)
Acrylic polyol resin (WE301 manufactured by DIC Corporation) 0.24 parts by mass (solid content)
Ethanol 5.0 parts by mass The pH was adjusted to 7.0 using 1N sodium hydroxide and adjusted to 48 parts by mass with water.

<Photopolymerizable photosensitive layer / over layer>
The above manner resulting hydrophilic layer, a photopolymerizable photosensitive layer coating solution 20 g / m 2 ^(wet coating amount) below, the over layer coating solution 30 g / m 2 ^(wet coating amount ) Was applied in this order with a continuous coater, and dried in a drying zone at 50 ° C. for 7 minutes. The surface temperature of the coated product at the end of the drying zone was 50 ° C. Then, it wound up in the winding chamber immediately adjacent to the humidity control zone through the humidity control zone immediately adjacent to the end of the drying zone. Thereafter, the wound-up coating was heated in a heating cabinet for 24 hours to obtain a negative photosensitive lithographic printing plate 1. The environment of the humidity control zone, the winding chamber, and the heating chamber is 40 ° C. and 40% RH.

<Photopolymerizable photosensitive layer coating solution>
Polymer B SP-1 1.1 parts by mass (solid content)
Photopolymerization initiator BC-6 0.2 parts by mass (solid content)
Photopolymerization initiator T-9 0.05 parts by mass (solid content)
Sensitizing dye VS-8 0.08 parts by mass (solid content)
0.25 parts by mass of blue pigment (solid content)
1,3-dioxolane 10ml
This was adjusted to 20 parts by mass with 1,3-dioxolane.

<Over layer>
PVA105 (manufactured by Kuraray Co., Ltd .: polyvinyl alcohol) 2.2 parts by mass (solid content)
Surfactant 0.5 parts by weight The amount was adjusted to 30 parts by weight with water.

For the obtained negative photosensitive lithographic printing plate (Comparative Examples 1 to 5, Inventions 1 to 8), using a plate setter (VIPLAS, manufactured by Mitsubishi Paper Industries Co., Ltd.) equipped with a 405 nm violet laser, 1500 dpi 150 lines Were exposed at an exposure dose of 100 μJ / cm ² .

<Chemical-less development processing>
The exposed plate was immersed in water at 25 ° C. for 30 seconds, and the surface having the photosensitive layer was lightly rubbed with a cellulose sponge to develop the plate, thereby obtaining a printing plate.

<Printing durability test method>
Each plate obtained by the above development processing is mounted on a printing machine Ryobi 560, 10% by mass isopropyl alcohol aqueous solution as a moisturizing liquid, and F Nippon Gloss ink (hard type) manufactured by Dainippon Ink & Chemicals, Inc. as ink. Printing was performed using the 100th and 1000th sheets, and samples up to 30,000th were sampled every 1000 sheets. The conditions during printing were an indoor temperature of 23 ° C. and an indoor humidity of 55% RH.

<Evaluation criteria for printing durability>
In the above 1000th to 30,000th printed matter (every 1000th printed matter), the image portion was visually observed for defects, and the printing durability was evaluated according to the following criteria. The results are shown in Table 1. In addition, printing durability is so good that the numerical value of evaluation criteria is large.
5: No defect in the image area even at the 30,000th image 4: Defect occurs in the image area between the 21,000th image and the 299000th image: The 31,000th image to the 20,000th image A defect occurs in the image area during the period 2: A defect occurs in the image area between the 2000th sheet and the 10,000th sheet.

<Print stain evaluation method>
Each plate obtained by the above development processing is mounted on a printing press Ryobi 660, 2% by mass solution of SLM-OD50 (Mitsubishi Paper Co., Ltd.) as a moisturizing liquid, and DIC F gloss purple (soft) as ink. Type) was printed, and samples from the 1000th sheet to the 15,000th sheet were sampled every 1000 sheets. The conditions during printing were an indoor temperature of 23 ° C. and an indoor humidity of 55% RH.

<Print stain evaluation criteria>
In the printed materials (every 1000 sheets) from the 1000th sheet to the 15,000th sheet, the print stain on the non-image area was visually evaluated according to the following criteria. The results are shown in Table 1. In addition, it is excellent in dirt resistance, so that the numerical value of evaluation criteria is large.
5: No smudges are seen in the non-image area at the 15,000th sheet. The smudges occur in the non-image area between the 4th 10,000th sheet and the 14,000th sheet. Stain occurs in the non-image area between the eyes 2: Stain occurs in the non-image area between the 3000th sheet and the 5000th sheet. Stain occurs in the non-image area after the 1: 2000th sheet.

  As can be seen from Table 1, according to the present invention, it is understood that a negative photosensitive lithographic printing plate having excellent printing durability and improved generation of printing stains can be obtained.

Claims (1)

  A lithographic printing plate in which a hydrophilic layer and an image forming layer are laminated in this order on a support, a titanium dioxide dispersion in which titanium dioxide is dispersed in the presence of colloidal silica, the mixing ratio of titanium dioxide and colloidal silica A lithographic printing plate characterized in that the hydrophilic layer contains a dispersion formed by dispersing under a condition that is titanium: colloidal silica = 1.5: 1 to 4: 1.