JP2012128306A - Photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate which has sufficient performance for printing durability in an image area and resistance to scumming in a non-image area.SOLUTION: In a photosensitive lithographic printing plate having at least a hydrophilic layer containing colloidal silica and a photopolymerized photosensitive layer in this order on a plastic film support, a hydrophilic auxiliary layer is provided between the hydrophilic layer and the photopolymerized photosensitive layer, and the hydrophilic auxiliary layer contains a hydrophilic polymer that is 50 mass% or more to the entire solid portion in the hydrophilic auxiliary layer.

Description

  The present invention relates to a photosensitive lithographic printing plate having at least a hydrophilic layer and a photopolymerizable photosensitive layer in this order on a plastic film support, and more particularly to a photosensitive lithographic printing plate capable of chemicalless development.

  In recent years, computer-to-plate (CTP) technology that directly outputs digital data formatted on a computer screen to a lithographic printing plate has been developed along with the digitization of the plate making system, and various plates equipped with various lasers as output machines. The development of setters and photosensitive lithographic printing plates compatible with these is being actively pursued. As such an output machine, an output machine using various lasers such as a blue-violet semiconductor laser (violet laser), a helium neon laser, a red LED, a near infrared laser, an infrared laser, and an argon laser is preferably used.

  As a lithographic printing plate having a photopolymerizable photosensitive layer corresponding to such various lasers, for example, JP-A-9-134007 discloses a radically polymerizable compound having an ethylenically unsaturated bond, a photosensitizing dye, A lithographic printing plate containing a polymerization initiator is disclosed, and JP-A-5-5988, JP-A-5-194619, JP-A-2000-98603, and the like disclose combinations of an organic boron anion and a dye. JP-A-4-31863, JP-A-6-43333, etc. disclose a combination of a dye and an s-triazine compound, and JP-A-7-20629 and JP-A-6-36633. JP-A-7-271029 discloses a combination of a resole resin, a novolac resin, an infrared absorber and a photoacid generator. No. 2 and JP-A No. 11-231535 disclose a combination of a specific polymer, a photoacid generator and a near-infrared sensitizing dye, and JP-A No. 2001-290271 discloses a side chain. A lithographic printing plate using a polymer having a phenyl group substituted with a vinyl group is disclosed. JP-A-2005-274695 and 2007-25220 disclose a lithographic printing plate having a photopolymerizable photosensitive layer corresponding to a violet laser light source.

  In recent years, there has been proposed a photosensitive lithographic printing plate that avoids the use of an alkaline developer and can be developed with water or the like. For example, Japanese Patent Application Laid-Open No. 2003-215801 (Patent Document 1) discloses a cationic water-soluble polymer having a phenyl group substituted with a vinyl group in the side chain, or a phenyl group substituted with a vinyl group in the side chain and a sulfonate group. A negative photosensitive lithographic printing plate having a water-soluble polymer having a photosensitive layer and a photosensitive layer containing a photopolymerization initiator or an acid generator is disclosed.

  The processing steps of the photopolymerizable photosensitive lithographic printing plate corresponding to various laser light sources as described above are developed by using an automatic developing machine after being exposed by an output machine having various laser light sources. However, a lithographic printing plate having, for example, an anodized aluminum support as a support cannot be stored compactly in the output machine, and there is a problem that the area occupied by the output machine becomes large.

  Photosensitive lithographic printing plates using a plastic film support that can be stored compactly in an output machine generally have a hydrophilic layer on the plastic film support. Examples of such a hydrophilic layer include a hydrophilic resin layer made of a (meth) acrylate polymer having a hydroxyalkyl group described in JP-B-49-2286, and a urea resin described in JP-B-56-2938. A hydrophilic layer composed of a pigment, a hydrophilic layer obtained by curing an acrylamide polymer described in JP-A-48-83902 with aldehydes, and a water-soluble melamine described in JP-A-62-280766 A hydrophilic layer obtained by curing a composition containing a resin, polyvinyl alcohol and a water-insoluble inorganic powder, and a water-soluble polymer containing a repeating unit having an amidino group in the side chain described in JP-A-8-184967. Hydrolyzed layer obtained by curing, a hydrolyzed tet containing a hydrophilic (co) polymer described in JP-A-8-272087 A hydrophilic layer cured with an alkyl orthosilicate, a hydrophilic layer having an onium group described in JP-A-10-296895, and a crosslinked hydrophilic polymer having a Lewis base moiety described in JP-A-11-311861 A hydrophilic layer obtained by three-dimensional crosslinking by interaction with a valent metal ion, a hydrophilic layer containing a hydrophilic resin and a water-dispersible filler described in JP-A No. 2000-122269 are known.

  However, it has been difficult for the photosensitive lithographic printing plate having the hydrophilic layer described above to obtain sufficient printing durability and stain resistance. In particular, in a negative photosensitive lithographic printing plate that can be developed with water or the like, the oleophilicity of an image obtained by chemicalless development represented by water tends to be low, and a sufficient image density should be obtained during printing. When the ink feed amount was increased with a printing press, it was difficult to obtain sufficient stain resistance.

  As a technique for solving such a problem, Japanese Patent Application Laid-Open No. 2008-265297 (Patent Document 2) contains a water-soluble polymer on a support, a crosslinking agent for crosslinking the water-soluble polymer, and colloidal silica, A photosensitive lithographic printing plate having a hydrophilic layer in which the ratio of the water-soluble polymer and colloidal silica is specified is disclosed. Further, JP 2009-226596 A (Patent Document 3) discloses that the hydrophilic layer includes at least a water-soluble polymer and A photosensitive lithographic printing plate containing inorganic fine particles and having a film surface pH value of 7.0 or more is disclosed. In addition, as a lithographic printing plate containing a water-soluble resin in a hydrophilic layer, Japanese Patent Application Laid-Open No. 2005-035003 (Patent Document 4) discloses inorganic fine particles such as metal oxide fine particles and colloidal silica in a hydrophilic layer that becomes a non-image portion. And a lithographic printing plate containing a water-soluble resin such as a polysaccharide. JP-A 2006-306031 (Patent Document 5) discloses a lithographic printing plate in which a water-soluble polymer and an alkoxide compound are coated on a support. Is disclosed. However, sufficient stain resistance cannot be obtained, and further improvement has been demanded.

JP 2003-215801 A JP 2008-265297 A JP 2009-226596 A JP 2005-035003 A JP 2006-306031 A

  An object of the present invention is to provide a printing planographic printing plate having a hydrophilic layer containing colloidal silica and a photopolymerizable photosensitive layer in this order on a plastic film support. It is an object of the present invention to provide a photosensitive lithographic printing plate capable of obtaining sufficient performance with respect to the soil resistance.

The above object has been achieved by the following invention.
1) A photosensitive lithographic printing plate having at least a hydrophilic layer containing colloidal silica and a photopolymerizable photosensitive layer in this order on a plastic support, the hydrophilic layer and the photopolymerizable photosensitive layer; A photosensitive lithographic printing plate comprising a hydrophilic auxiliary layer in between, wherein the hydrophilic auxiliary layer contains 50% by mass or more of a hydrophilic polymer based on the total solid content of the hydrophilic auxiliary layer.

  According to the present invention, photosensitive lithographic printing that improves the anti-smudge property of the non-image part without degrading the printing durability of the image part, and as a result, sufficient performance can be obtained in both the printing durability and the anti-smudge property. A version can be provided.

The present invention will be described in detail below.
The photosensitive lithographic printing plate of the present invention is a photosensitive lithographic printing plate having at least a hydrophilic layer, a hydrophilic auxiliary layer, and a photopolymerizable photosensitive layer in this order on a plastic film support. As the layer structure of this photosensitive lithographic printing plate, in addition to the hydrophilic layer, hydrophilic auxiliary layer, and photopolymerizable photosensitive layer described above, for example, an intermediate layer may be provided between the plastic film support and the hydrophilic layer. A protective layer may be provided on the top of the photopolymerizable photosensitive layer (with the support facing down), or the back side of the plastic film support (opposite to the surface of the photopolymerizable photosensitive layer as viewed from the support) A back layer may be provided.

[Support]
Examples of the support for the photosensitive lithographic printing plate of the present invention include various plastic films. Representative examples of the plastic film support include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyvinyl acetal, polycarbonate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, and cellulose nitrate. Polyethylene terephthalate and polyethylene naphthalate are preferably used. These films are preferably subjected to hydrophilic treatment on the surface before providing various functional layers. Examples of such hydrophilic treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. .

[Middle layer]
The photosensitive lithographic printing plate of the present invention preferably has an intermediate layer containing a hydrophilic polymer and a crosslinking agent between the plastic film support and the hydrophilic layer. Examples of the hydrophilic polymer include polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, gelatin and the like, and gelatin or polyacrylic acid is preferable. This intermediate layer provides better printing durability and stain resistance, but this effect is due to the liquid absorbing effect that the intermediate layer can store water to some extent and the cushioning effect that cushions the mechanically applied force. Presumed to be obtained.

  The gelatin contained in the intermediate layer has an average molecular weight of 3000 or more. For example, alkaline gelatin using cow bone or cow skin as raw material, acidic gelatin using pork skin as raw material, modified gelatin (eg, phthalated gelatin) Impurities contained in these gelatins (for example, salts such as calcium ions, sodium ions, chloride ions, lipids, nucleic acids and their degradation products, aldehydes, etc.) are reduced by purification and desalting treatment. And gelatin. The polyacrylic acid has an average molecular weight of 3000 or more and is a polyacrylic acid or a copolymer of acrylic acid and another monomer (for example, acrylic acid-methacrylic acid copolymer, acrylic acid- (4-carboxy) styrene copolymer). Polymer, acrylic acid-maleic acid copolymer, acrylic acid-acrylamide copolymer), and polyacrylic acids such as modified acrylic acid. Gelatin or polyacrylic acid is used in the intermediate layer of the present invention. May be.

  The dry weight of the intermediate layer is preferably between 0.5 g and 50 g per square meter, more preferred range is between 1 g and 25 g per square meter, and most preferred range is between 3 g and 15 g per square meter. It is. When the dry weight of the intermediate layer is small, the ground stain resistance of the non-image area may deteriorate, or the printing durability of the image area may deteriorate. Further, if the dry weight of the intermediate layer is excessive, the printing durability of the image area may be deteriorated.

  The intermediate layer of the present invention preferably contains a cross-linking agent for cross-linking the hydrophilic polymer, and examples of the cross-linking agent include various known compounds. Specific examples include epoxy compounds, aziridine compounds, oxazoline compounds, isocyanate compounds and derivatives thereof, aldehyde compounds such as formalin, methylol compounds, hydrazide compounds, and the like. Particularly preferred crosslinking agents are epoxy compounds, aldehyde compounds, and methylol. Of these, epoxy compounds are particularly preferred.

  As the epoxy compound, a compound having two or more epoxy groups in the molecule is preferably used. Specific examples of preferred epoxy compounds are shown below.

  Specific examples of preferable compounds as the aziridine compound are shown below.

  As the oxazoline compound, a compound containing two or more groups represented by the following general formula (1) as a substituent in the molecule is preferable, and various commercially available compounds are provided, for example, from Nippon Shokubai Co., Ltd. under the trade name Epocross. Various grades of compounds are preferably used.

  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 self-emulsifying isocyanate compounds include Japanese Patent Publication No. 55-7472 (US Pat. No. 3,996,154) and Japanese Patent Laid-Open No. 5-222150 (US 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.

  Examples of aldehyde compounds and methylol compounds such as formaldehyde and glyoxal include formaldehyde, glyoxal, and various N-methylol compounds as shown below.

  Specific examples of compounds that can be preferably used as the hydrazide compound are shown below.

  There is a preferred range for the ratio of the various crosslinking agents and hydrophilic 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 hydrophilic polymer.

  In addition to the inorganic porous compound, gelatin or polyacrylic acid, and the crosslinking agent, the intermediate layer of the present invention may contain polymers, latexes, surfactants, pH adjusters and the like.

[Hydrophilic layer]
The hydrophilic layer of the photosensitive lithographic printing plate of the present invention contains colloidal silica. Colloidal silica is a variety of shapes and particles such as a sphere, needle shape, irregular shape, or a necklace shape in which spherical particles are connected, preferably having an average particle size of 5 to 200 nm as measured by a light scattering particle size distribution analyzer. A silica sol having a diameter of silica particles and stably dispersed in water is preferably used. As such materials, various colloidal silicas are provided, for example, under the name of Snowtex from Nissan Chemical Industries, Ltd., and as a spherical silica sol, Snowtex XS (particle diameter 4 to 6 nm), Snowtex S (particle diameter 8) To 11 nm), Snowtex 20 (particle size 10 to 20 nm), Snowtex XL (particle size 40 to 60 nm), Snowtex YL (particle size 50 to 80 nm), Snowtex ZL (particle size 70 to 100 nm), Snowtex As an acidic type silica sol from which MP-2040 (particle diameter: 200 nm) and sodium salt on the surface have been removed, Snowtex OXS, OS and the like can be preferably used. Examples of the needle-like or amorphous silica sol include Snowtex UP, OUP, and Fine Cataloid F-120 available from Catalyst Kasei Kogyo Co., Ltd. Examples of the necklace-shaped silica sol include Snowtex PS-S (particle diameter 80 to 120 nm), PS-M (particle diameter 80 to 150 nm), and PS-SO and PS-MO which are acidic types thereof.

  The hydrophilic layer of the present invention preferably contains a water-soluble resin together with the above-described colloidal silica, and more preferably contains the water-soluble resin and colloidal silica in a mass ratio of 1: 1 to 1: 3. . In addition to the colloidal silica, the hydrophilic layer contains other inorganic fine particles, such as titanium dioxide particles, alumina particles (for example, aluminum oxide hydrate, aluminum hydroxide), zeolite, particles made of other metal oxides, and the like. These other inorganic fine particles may be subjected to a surface treatment on the particle surface.

  Examples of the water-soluble resin contained in the hydrophilic layer of the present invention include polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, gelatin, and the like. In particular, a negative photosensitive lithographic plate having excellent anti-stain resistance in non-image areas. Since a printing plate is obtained, a polymer represented by the following general formula (2) is preferably used.

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

  It is important that the water-soluble polymer represented by the general formula (2) contains a reactive group in the molecule for allowing a crosslinking reaction to proceed efficiently with a crosslinking agent described later. Examples of such reactive groups include a carboxy 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 (2), acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, cinnamic acid Carboxy group-containing monomers such as maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene, acrylamide-N-glycolic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylamino Ethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene Amino group-containing monomers such as 4-aminomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, 4-vinylpyridine, 2 Nitrogen-containing heterocycle-containing monomers such as vinylpyridine and N-vinylimidazole, (meth) acrylamides such as N-methylolacrylamide and 4-hydroxyphenylacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy Examples thereof include hydroxyalkyl (meth) acrylates such as propyl acrylate, 2-hydroxypropyl methacrylate, and glycerol monomethacrylate, and acetoacetoxy methacrylate, but are not limited to these examples.

  In the general formula (2), X, which is the ratio of the repeating unit A in the copolymer, is 1 to 40, and if it is less than this range, sufficient film strength cannot be obtained even if the crosslinking reaction proceeds. In some cases, if the amount is larger than this range, the effect of introducing the repeating unit B for imparting water solubility described below is reduced, and the affinity of the hydrophilic layer for water may be reduced.

  Furthermore, as a monomer for giving the repeating unit B in the general formula (2), vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, 2- Sulfonic acid group-containing monomers such as acrylamido-2-methylpropanesulfonic acid and their salts, Phosphoric acid group-containing monomers such as vinylphosphonic acid and their salts, dimethyl diallyl ammonium chloride, acrylic acid-2- (trimethylammonio) Ethyl ester, methacrylic acid-2- (trimethylammonio) ethyl ester, acrylic acid-2- (triethylammonio) ethyl ester, methacrylic acid-2- (triethylammonio) ethyl ester, (3-acrylamidopropyl) trime Quaternary ammonium salts such as ruammonium chloride, 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. Specific examples of preferable water-soluble polymers in the present invention are shown below. In the present invention, water-soluble means that 0.5 g or more of a water-soluble polymer is dissolved in 1 L of water.

  The hydrophilic layer of the present invention preferably contains a crosslinking agent, and can be selected from the same group of compounds as the crosslinking agent that can be contained in the above-mentioned intermediate layer. There is a preferred range for the ratio. 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 resin. Particularly preferred crosslinking agents are epoxy compounds.

  The hydrophilic layer of the present invention can contain a surfactant, a pH adjuster and the like in addition to the water-soluble polymer, inorganic fine particles, and crosslinking agent described above.

  There is a preferred range for the dry weight of the hydrophilic layer, specifically, the dry weight of the hydrophilic layer is between 0.6 g and 10 g per square meter, and the preferred range is between 2 g and 6 g per square meter. It is.

  The hydrophilic layer of the present invention can contain a surfactant, a pH adjuster and the like in addition to the water-soluble resin, inorganic fine particles, and hardener.

[Hydrophilic auxiliary layer]
The hydrophilic auxiliary layer of the photosensitive lithographic printing plate of the present invention is located between the hydrophilic layer and the photopolymerizable photosensitive layer described above, and the hydrophilic auxiliary layer is in the total solid content of the hydrophilic auxiliary layer. On the other hand, it contains 50% by mass or more of a hydrophilic polymer.

  Preferred hydrophilic polymers include polysaccharides in addition to the hydrophilic polymer contained in the intermediate layer and the water-soluble resin contained in the hydrophilic layer. Specific polysaccharides include welan gum, diyutan gum, guar gum, locust bean gum, tara gum, cassia gum, xanthan gum, gum arabic, tragacanth gum, caraya gum, galactomannan, glucomannan, pectin, carrageenan, mannose, glucuronic acid, alginic acid, Examples include, but are not limited to, starch, amylose, amylopectin, glycogen, cellulose, dextrin, glucan, fructan, chitosan, chitin, agarose, heparin, hyaluronic acid, xyloglucan and the like. The preferred hydrophilic polymer contained in the hydrophilic auxiliary layer includes the polymer represented by the general formula (2) or the polysaccharide, and the polysaccharide is particularly preferred.

  The hydrophilic auxiliary layer of the present invention contains 50% by mass or more of the hydrophilic polymer based on the total solid content of the hydrophilic auxiliary layer, and the more preferable content of the hydrophilic polymer is 70% by mass or more, and more preferably 85%. It is at least 9% by mass, most preferably at least 92.5% by mass. The hydrophilic auxiliary layer of the present invention has a preferable dry mass. If the dry mass is too large, the adhesiveness of the image layer may be lowered and printing durability may be deteriorated. If the dry mass is too small, the hydrophilic polymer may be used. In some cases, the soil dirt resistance improving effect due to may not be obtained. A preferred range for the dry weight of the hydrophilic auxiliary layer is from 1 mg to 1000 mg, more preferably from 5 mg to 600 mg, and most preferably from 10 mg to 300 mg per square meter.

  The hydrophilic auxiliary layer of the present invention preferably contains inorganic fine particles. Examples of the inorganic fine particles include colloidal silica, titanium dioxide particles, alumina particles (for example, aluminum oxide hydrate, aluminum hydroxide), zeolite, and other metal oxide particles, among which colloidal silica is preferable. Moreover, it is preferable that a hydrophilic auxiliary layer contains a crosslinking agent, and it is preferable to use in 1-40 mass% with respect to a hydrophilic polymer.

  The hydrophilic auxiliary layer of the present invention can contain a silane coupling agent, a surfactant, a pH adjuster and the like in addition to the hydrophilic polymer and the inorganic fine particles.

[Photopolymerizable photosensitive layer]
The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate of the present invention is a negative photosensitive layer containing a polymer containing a monomer having a polymerizable double bond as a copolymerization component and a photopolymerization initiator. preferable. Examples of the monomer having a polymerizable double bond 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. Examples include acrylamide, α-chlorovinyl methacrylate, α-chlorovinyl acrylate, 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, the developability of the photopolymerizable photosensitive layer in the unexposed area is promoted.

  As a more preferable embodiment of the above-described copolymer, a copolymer having a monomer having a phenyl group substituted with a vinyl group as a monomer having a polymerizable double bond can be mentioned. The phenyl group substituted with a vinyl group is a vinyl group substituted with an aromatic ring such as a benzene ring or a naphthalene ring, and the vinyl group is a halogen atom, a carboxy 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, an aryloxy group and the like, and the aromatic ring may have a substituent. By incorporating a copolymer with a water-soluble group and a phenyl group with a vinyl group substituted in the side chain in the polymer structure into the photopolymerizable photosensitive layer, the recombination of styryl radicals generated by the generated radicals increases the recombination. A sensitive negative photosensitive lithographic printing plate is obtained. The phenyl group substituted with a vinyl group is specifically represented by the following general formula (3).

In the formula, R ₁₁ , R ₁₂ and R ₁₃ may be the same or different and are each a hydrogen atom, halogen atom, carboxy 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, a carboxy 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, a hydroxy group, and an alkoxy group. , Aryloxy group, alkylthio group, arylthio group, alkyl It may be substituted with an amino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group or the like. Among these groups, those in which R ₁₁ 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 ₁₂ and R ₁₃ are hydrogen atoms are particularly preferable.

In the formula, R ₁₄ represents a hydrogen atom, a halogen atom, a carboxy group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, 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 carboxy 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, an alkynyl group, and a hydroxy 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, an arylsulfonyl group and the like.

In the formula, m ₁ represents an integer of 0 to 4, and p ₁ represents an integer of 0 or 1. 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 comprising a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group.

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 carboxy 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.

  As the most 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.

  Specific examples of the carboxylic acid type polymer in the present invention are shown below.

  As the most 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 sulfonic acid group in the structure as a water-soluble group-containing monomer (for example, 3-sulfopropyl methacrylate, 4-sulfostyrene, 4-sulfo-n-butylmethacrylamide, sulfo-tert-butylacrylamide, etc.) as a copolymerization component, and a phenyl group and a sulfonic acid group in which a vinyl group is substituted on the side chain (Hereinafter referred to as sulfonic acid type polymer), and the sulfonic acid group forms a salt (for example, sodium salt, potassium salt, triethylammonium salt, lithium salt, tetramethylammonium salt, etc.). May be. In this sulfonic acid type polymer, since the sulfonic acid group in the structure enhances water solubility, the above-mentioned alkaline developer may be used, but the pH value of the developer which is a more preferred embodiment of the present invention is 4.0 or more. A method using a chemicalless developer in the range of less than 10.0 (hereinafter referred to as chemicalless development) is possible. However, the oleophilicity of the image formed by the sulfonic acid type polymer is relatively low, and when the ink feed amount is increased by the printing machine so as to obtain a sufficient image density at the time of printing, the non-image portion is particularly easily stained. . 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. In addition, the sulfonic acid type polymer, like the carboxylic acid type polymer described above, has a phenyl group having a vinyl group substituted on the side chain, so that high sensitivity can be achieved.

  Specific examples of the sulfonic acid type polymer in the present invention are shown below.

  The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate of the present invention contains a photopolymerization initiator. 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) an organic boron salt compound, (b) an aromatic onium salt compound, (c) an organic peroxide, (d) a hexaarylbiimidazole compound, ( e) ketoxime ester compounds, (f) azinium salt compounds, (g) active ester compounds, (h) metallocene compounds, (i) trihaloalkyl-substituted compounds, (j) aromatic ketones, etc. The polymerization initiator is (a) an organic boron salt compound and (i) a trihaloalkyl-substituted compound.

  Examples of (a) organic boron salt compounds include JP-A-8-217813, JP-A-9-106242, JP-A-9-188585, JP-A-9-188686, and 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.

  (B) Examples of the aromatic onium salt compound include N, P, As, Sb, Bi, O, S, Se, Te or I aromatic onium salts. Examples of such aromatic onium salt compounds 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 ( Peroxidation of p-isopropylcumylperoxycarbonyl) benzophenone, di (tert-butyldiperoxy) isophthalate, etc. Ester systems are preferred.

  (D) Examples of hexaarylbiimidazole compounds include lophine dimers described in JP-B-45-37377 and JP-B-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 ', 5,5'-tetraphenylbiimidazole and the like.

  (E) Examples of ketoxime ester compounds 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-toluenesulfonyloxyimino) butan-2-one , 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one and the like.

  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-62-2623, etc., and active sulfonates described in JP-B-63-14340, JP-A-59-174831, etc. be able to.

  (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) Preferred examples of aromatic ketones include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY”. P. FUOASSIER, J.A. F. RABEK (1993), P.A. 77-P. 177, a compound having a benzophenone skeleton or a thioxanthone skeleton, an α-thiobenzophenone compound described in Japanese Patent Publication No. 47-6416, a benzoin ether compound described in Japanese Patent Publication No. 47-3981, and Japanese Patent Publication No. 47-22326 Α-substituted benzoin compounds described in JP-A No. 47-23664, benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, and JP-B-60-26483 Dialkoxybenzophenones, benzoin ethers described in JP-B-60-26403, JP-A-62-181345, p-di (dimethylaminobenzoyl) benzene described in JP-A-2-211452, A thio-substituted aromatic group described in JP-A-61-194062 Ton, an acylphosphine sulfide described in JP-B-2-9597, an acylphosphine described in JP-B-2-9596, a thioxanthone described in JP-B-63-61950, and JP-B-59-42864 Can be mentioned.

  The photopolymerization initiator used in the present invention includes compounds known as photoacid generators. As the photoacid generator, 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. 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.

  The organic boron salt compound which is a particularly preferable photopolymerization initiator in the present invention is composed of an organic boron salt, and the organic boron anion constituting the organic boron salt is represented by the following general formula (4).

In the formula, each of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ may be the same or different, and represents an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. To express. Of these, it is particularly preferred that one of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ 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 (4) shown above, and alkali metal ions and onium compounds are preferably used as cations forming the salt. The 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. Specific examples of particularly preferred organic boron salts are shown below.

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

  The above photopolymerization initiators may be used alone or in any combination of two or more. The content of the photopolymerization initiator is preferably in the range of 1 to 100 parts by mass and more preferably in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the polymer containing a monomer having a polymerizable double bond as a copolymerization component. Is particularly preferred.

  The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably contains a sensitizing dye. Such a sensitizing dye sensitizes the aforementioned photopolymerization initiator to the absorption maximum wavelength of the sensitizing dye. This makes it possible to cope with exposure by various lasers (for example, a blue-violet semiconductor laser and a near infrared laser). And when the said photoinitiator is an organic boron salt, it has the characteristic that the sensitivity with respect to various laser beams becomes very high by combining with this sensitizing dye. The sensitizing dye specifically sensitizes the decomposition of the photopolymerization initiator in a wavelength range of 380 to 1300 nm, and includes various cationic dyes, anionic dyes, and merocyanine as neutral dyes having no charge. , Coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Specific examples of the sensitizing dye according to the present invention are shown below.

  As the sensitizing dye of the present invention, a system that imparts sensitivity to light in the wavelength region of 750 to 1100 nm is preferable for near infrared laser, and the sensitizing dye needs to have absorption in such a wavelength region. There is a particularly preferred specific example used for such purposes.

  Specific examples of particularly preferable sensitizing dyes used for blue-violet semiconductor lasers having a light source at a short wavelength as sensitizing dyes of the present invention are shown below.

  The sensitizing dyes may be used alone or in any combination of two or more. The content of the sensitizing dye is preferably in the range of 0.1 to 50 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer containing a monomer having a polymerizable double bond as a copolymerization component. The range of is particularly preferable.

  Addition of a colorant can also be preferably performed as another element constituting the photopolymerizable photosensitive layer. As a colorant, it is used for the purpose of enhancing the visibility of the image area after exposure and development processing, and various kinds of carbon black, phthalocyanine dye, triarylmethane dye, anthraquinone dye, azo dye, etc. Dyes and pigments can be used.

  About the element which comprises a photopolymerizable photosensitive layer, in addition to the above-mentioned element, other elements can be additionally contained for various purposes. For example, inorganic fine particles or organic fine particles are also preferably added for the purpose of preventing blocking of the photosensitive layer composition.

  There is a preferred range for the dry weight of the photopolymerizable photosensitive layer, preferably a dry weight ranging from 0.2 g to 5 g per square meter, most preferably 0.5 g to 3 g per square meter. It is a range.

  The photosensitive lithographic printing plate of the present invention may have a protective layer on the photosensitive layer as viewed from the support, and promotes deactivation of radical species generated by laser exposure in the photopolymerizable photosensitive layer. A protective layer with the ability to block oxygen as a factor is preferable. Especially when the laser light source of the exposure machine is a violet laser, a sufficient amount of energy cannot be obtained with a commercially available light source. It is particularly preferred. It is preferable to use a water-soluble polymer compound having relatively excellent crystallinity for the protective layer, and specifically, polyvinyl alcohol, vinyl alcohol / vinyl phthalate copolymer, vinyl acetate / vinyl alcohol / vinyl phthalate copolymer. Examples thereof include water-soluble polymers such as polymers, vinyl acetate / crotonic acid copolymers, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, polyacrylic acid, and polyacrylamide, which can be used alone or in combination. . Of these, the use of polyvinyl alcohol as a main component gives the best results in terms of basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol used in the protective layer is 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. Also good. 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.

  The content of the polyvinyl alcohol in the protective layer is preferably 50% by mass or more, more preferably 70% by mass or more in terms of solid content.

  Polyvinyl alcohol, other water-soluble polymers, various organic compounds, and inorganic compounds may be added to the protective layer of the present invention. A surfactant may be added for the purpose of improving the coating property for coating on the photopolymerizable photosensitive layer.

  The dry weight of the protective layer of the present invention is selected in consideration of fogging, adhesion and scratch resistance in addition to oxygen barrier properties and development removability, but is preferably between 0.1 g and 3 g per square meter.

[Plate making method]
The photosensitive lithographic printing plate of the present invention is subjected to contact exposure or laser scanning exposure, and then a pattern is formed by removing uncured portions with an alkaline developer or a chemicalless developer. In a negative photosensitive lithographic printing plate, the exposed portion is crosslinked, so that the solubility in an alkaline developer or a chemical-less developer is lowered, and an image portion is formed.

  As the plate making method of the photosensitive 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, 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.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as well as the effects.

(Preparation of photosensitive lithographic printing plate 1)
<Intermediate layer>
On a polyester film support with a thickness of 100 μm, apply the following intermediate layer formulation with a wire bar so that the dry mass is 8 g (per square meter), and dry it with a dryer at 50 ° C. for 10 minutes. Further, the dried product was heated in a dryer at 40 ° C. for 2 days.

<Intermediate layer prescription>
Gelatin 10 parts by weight Crosslinker H-6 1 part by weight Ion-exchanged water 100 parts by weight pH adjuster (pH value adjusted to 5.0 with aqueous sodium hydroxide or sulfuric acid)

<Hydrophilic layer>
On the said intermediate | middle layer, it apply | coated so that a dry mass might be set to 4.0g (per square meter) with a wire bar with the following hydrophilic layer prescription, and it dried for 10 minutes with a 50 degreeC dryer.

<Hydrophilic layer formulation>
* Colloidal silica indicates dry mass.
Water-soluble resin (WP-4) 1 part by mass Colloidal silica Snowtex PS-M manufactured by Nissan Chemical Industries, Ltd.
(Particle diameter 80-150 nm) 1.5 parts by mass Crosslinker H-9 0.2 parts by mass pH adjuster (pH value adjusted to 5.0 with aqueous sodium hydroxide or sulfuric acid)
25 parts by mass of ion exchange water

<Hydrophilic auxiliary layer>
On the above hydrophilic layer, the following hydrophilic auxiliary layer formulation 1 is applied with a wire bar so that the dry mass is 0.2 g (per square meter), and dried at 50 ° C. for 10 minutes. Went. Thereafter, a photopolymerizable photosensitive layer was applied on the hydrophilic auxiliary layer so as to have a dry mass of 1.5 g (per square meter) with a wire bar according to the following photopolymerizable photosensitive layer formulation. Drying was performed for 3 minutes in a dryer at 0 ° C. Further, a protective layer is applied on the photopolymerizable photosensitive layer with a wire bar in the following protective layer formulation so that the dry mass becomes 1.5 g (per square meter), and 10% by a dryer at 70 ° C. Drying was performed for a minute to obtain a photosensitive lithographic printing plate 1.

<Hydrophilic auxiliary layer formulation 1>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer Xanthan gum 0.012 parts by mass Inorganic fine particles SNOWTEX PS-M 0.00764 parts by mass manufactured by Nissan Chemical Industries, Ltd. Crosslinker H-9 0.00036 parts by mass Ion-exchanged water 10 parts by mass

<Photopolymerizable photosensitive layer formulation>
Sulfonic acid type polymer SP-1 1 part by weight Photopolymerization initiator BC-4 0.1 part by weight Photopolymerization initiator T-8 0.1 part by weight Sensitizing dye S-19 0.05 part by weight Colorant Victoria Blue 0 .2 parts by mass Acetone 5 parts by mass Ethanol 5 parts by mass Tetrahydrofuran 10 parts by mass

<Protective layer prescription>
Kuraray PVA-117 1 part by mass Ion-exchanged water 20 parts by mass

(Preparation of photosensitive lithographic printing plate 2)
The photosensitive lithographic printing plate 2 was prepared in the same manner except that a hydrophilic auxiliary layer was provided using the following hydrophilic auxiliary layer formulation 2 instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 2>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer Xanthan gum 0.016 parts by weight Inorganic fine particles Nissan Chemical Co., Ltd. Snowtex PS-M 0.00352 parts by weight Crosslinker H-9 0.00048 parts by weight Ion-exchanged water 10 parts by weight

(Preparation of photosensitive lithographic printing plate 3)
The photosensitive lithographic printing plate 3 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 3 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 3>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer Xanthan gum 0.018 parts by weight Inorganic fine particles Nissan Chemical Industries, Ltd. Snowtex PS-M 0.00146 parts by weight Crosslinker H-9 0.00054 parts by weight Ion-exchanged water 10 parts by weight

(Preparation of photosensitive lithographic printing plate 4)
The photosensitive lithographic printing plate 4 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 4 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 4>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer Xanthan gum 0.019 parts by weight Inorganic fine particles Nissan Chemical Industries Co., Ltd. Snowtex PS-M 0.00043 parts by weight Crosslinker H-9 0.00057 parts by weight Ion-exchanged water 10 parts by weight

(Preparation of photosensitive lithographic printing plate 5)
The photosensitive lithographic printing plate 5 was prepared in the same manner except that a hydrophilic auxiliary layer was provided using the following hydrophilic auxiliary layer formulation 5 instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 5>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer (hyaluronic acid) 0.019 parts by mass Inorganic fine particles Nissan Chemical Industries, Ltd. Snowtex PS-M 0.00043 parts by mass Crosslinker H-9 0.00057 parts by mass Ion-exchanged water 10 parts by mass

(Preparation of photosensitive lithographic printing plate 6)
The photosensitive lithographic printing plate 6 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 6 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 6>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer (WP-4) 0.019 parts by weight Inorganic fine particles Nissan Chemical Industries, Ltd. Snowtex PS-M 0.00043 parts by weight Crosslinker H-9 0.00057 parts by weight Ion-exchanged water 10 parts by weight

(Preparation of photosensitive lithographic printing plate 7)
The photosensitive lithographic printing plate 7 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 1 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 7>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer (WP-5) 0.019 parts by mass Inorganic fine particles Nissan Chemical Industries, Ltd. Snowtex PS-M 0.00043 parts by mass Crosslinker H-9 0.00057 parts by mass Ion-exchanged water 10 parts by mass

(Preparation of photosensitive lithographic printing plate 8)
The photosensitive lithographic printing plate 8 was prepared in the same manner except that a hydrophilic auxiliary layer was provided using the following hydrophilic auxiliary layer formulation 8 instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 8>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.)
0.019 parts by mass Inorganic fine particles Nissan Chemical Co., Ltd. Snowtex PS-M 0.00043 parts by mass Crosslinker H-9 0.00057 parts by mass Ion-exchanged water 10 parts by mass

(Preparation of photosensitive lithographic printing plate 9)
The photosensitive lithographic printing plate 9 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 9 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 9>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer gelatin (IK-195 manufactured by Nippi Gelatin Co., Ltd.)
0.019 parts by mass Inorganic fine particles Nissan Chemical Co., Ltd. Snowtex PS-M 0.00043 parts by mass Crosslinker H-9 0.00057 parts by mass Ion-exchanged water 10 parts by mass

(Preparation of photosensitive lithographic printing plate 10)
The photosensitive lithographic printing plate 10 was prepared in the same manner except that the hydrophilic auxiliary layer formulation 10 described below was used instead of the hydrophilic auxiliary layer formulation 1 used in the preparation of the photosensitive lithographic printing plate 1. Was made.

<Hydrophilic auxiliary layer formulation 10>
* The dry weight of inorganic fine particles is indicated.
Hydrophilic polymer Xanthan gum 0.008 parts by mass Inorganic fine particles Snowtex PS-M 0.01176 parts by mass manufactured by Nissan Chemical Industries, Ltd. Cross-linking agent H-9 0.00024 parts by mass Ion-exchanged water 10 parts by mass

(Preparation of photosensitive lithographic printing plate 11)
In preparing the photosensitive lithographic printing plate 1, a photosensitive lithographic printing plate 11 was prepared in the same manner as the photosensitive lithographic printing plate 1 except that the hydrophilic auxiliary layer was not provided.

<Exposure>
With respect to each of the photosensitive lithographic printing plates 1 to 10 thus produced, a 2400 dpi 175 line image was exposed to 100 μJ / cm ² using a plate setter (VIPLAS manufactured by Mitsubishi Paper Industries Co., Ltd.) equipped with a 405 nm violet laser. And exposed.

<Chemical-less development processing>
Each exposed plate exposed as described above is pasted on an aluminum plate having a thickness of 200 μm (the photopolymerizable photosensitive layer is on the upper side), and used as a PS plate made by Dainippon Screen Mfg. Co., Ltd. Development processing was performed using an automatic developing machine PD-1310 to obtain a plate for printing. As for the conditions of the development processing, the above-mentioned exposure has been completed by setting ion exchange water in the first tank of the automatic processor (having a Morton mechanism in the processing step), setting the liquid temperature to 30 ° C., and the processing time to 15 seconds. The plate was processed, the processed plate was taken out from the outlet of the first tank, and then naturally dried to obtain a water developing plate.

<Printing durability test method>
Each plate obtained by the above development processing is mounted on a printing press Ryobi 660, and printed using a 10% by mass isopropyl alcohol aqueous solution as a moisturizing liquid and T & K TOKA Supertech GT Black SOYA (medium type) as an ink. The printed material from the 1000th sheet up to the 20,000th sheet was 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 printed material from the 1000th sheet to the 20,000th sheet (every 1000 sheets), the image area with 5% halftone dots (small image area) is observed for defects with a 50 × magnifier, and the image area is printed. Sex was evaluated according to the following criteria. The results are shown in Table 1.
A: Defects are not observed in the image area even at the 20,000th sheet. O: Defects are observed in the image area between the 15,000th sheet and the 19,000th sheet. O: 10,000th sheet to 10,000. The occurrence of a defect in the image portion is observed between the 4000th sheet. Δ: The occurrence of a defect is observed in the image portion between the 6000th sheet and the 9000th sheet. Δ ×: An image between the 2000th sheet and the 5000th sheet. Occurrence of defects in the image area is observed x: Defects are observed in the image area on the 1000th sheet

<Soil stain resistance printing test method>
Each plate obtained by the above development processing is mounted on a printing press Ryobi 660, using a 10% by mass isopropyl alcohol aqueous solution as a moisturizing liquid, and UNIDOY 4CS G-1 Crimson (soft type) as ink. Printing was performed, and samples from the 1000th sheet to the 10,000th sheet were sampled every 1000 sheets. The conditions during printing were an indoor temperature of 23 ° C. and an indoor humidity of 55% RH.

<Evaluation criteria for soil resistance>
In the 1000th to 10,000th printed materials (every 1000th sheet), the soil resistance of the non-image area was visually evaluated according to the following criteria. The results are shown in Table 1.
A: No smudge is observed in the non-image area even at the 20,000th sheet. O: Occurrence of a smudge is observed in the non-image area between the 15,000th sheet and the 19,000th sheet. Between the 1st and 14,000th sheets, the occurrence of background smudge is observed in the non-image area. Δ: Between the 6000th sheet and the 9000th sheet, occurrence of the background smudge is recognized. Δ ×: 2000th sheet Generation of dirt on the non-image area is recognized between the 5,000th sheet and the non-image area on the 1000th sheet.

  From the results shown in Table 1, it is possible to obtain a good photosensitive lithographic printing plate excellent in printing durability and background stain resistance by setting the amount of the hydrophilic polymer contained in the hydrophilic auxiliary layer to 50% by mass or more. I understand.

Claims (1)

  A photosensitive lithographic printing plate having at least a hydrophilic layer containing colloidal silica and a photopolymerizable photosensitive layer in this order on a plastic support, the gap between the hydrophilic layer and the photopolymerizable photosensitive layer A photosensitive lithographic printing plate comprising a hydrophilic auxiliary layer, wherein the hydrophilic auxiliary layer contains 50% by mass or more of a hydrophilic polymer based on the total solid content of the hydrophilic auxiliary layer.