JP2008203349A - Photosensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative photosensitive lithographic printing plate which has a highly safe light feature not incurring soiled paper or printing failure when printing even if handled for long time under white fluorescent light. <P>SOLUTION: This negative photosensitive lithographic printing plate has a photosensitive layer containing a polymer containing a monomer having a polymerizing double bond on the side chain as a copolymerizing component, a photopolymerization initiator, and a tocopherol compound, on the base plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to a photosensitive lithographic printing plate for scanning exposure which forms an image using various lasers. In particular, the present invention relates to a negative photosensitive lithographic printing plate having sensitivity to light in the wavelength range of 380 nm to 1300 nm.

  The negative type photosensitive lithographic printing plate that has been widely used conventionally has a photosensitive coating film (photosensitive layer) coated on an aluminum support. In this coating film, the exposed portion (exposed portion) is cured, and the unexposed portion (unexposed portion) is eluted by a development process. The cured portion remains as an image portion and accepts ink during printing, while the eluted portion exposes the hydrophilic aluminum surface, and printing is performed by receiving water (fountain solution) during printing.

  In recent years, with the advance of image forming technology, photosensitive lithographic printing plates exhibiting high sensitivity to visible light have been demanded. For example, research on a photosensitive lithographic printing plate corresponding to an output machine using an argon laser, a helium / neon laser, a red LED, or the like has been actively conducted.

  Furthermore, with the remarkable progress of semiconductor lasers, a near-infrared laser light source of 750 to 1300 nm can be easily used, and photosensitive lithographic printing plates corresponding to the laser light have attracted attention.

  Examples of photosensitive lithographic printing plates that utilize photopolymerization and are compatible with near-infrared lasers include, for example, JP-A-8-114916, JP-A-2000-122273, JP-A-2002-278080, and JP-A-2002-283752. No., JP-A No. 2002-241547, JP-A No. 2004-126031, and the like.

  These photosensitive lithographic printing plates generally have to be loaded in a cassette or skid dedicated to a laser exposure device (image setter) prior to exposure. During this operation, the photosensitive lithographic printing plate is exposed to the light of a room fluorescent lamp. Performance may be degraded. In recent years, photosensitive lithographic printing plates have been required to have a brighter working environment, particularly a performance (high safe light property) that can withstand long-time handling under a white fluorescent lamp. If the photosensitive lithographic printing plate has low safelight properties, it can be handled by reducing the illuminance in the room or changing the type of fluorescent light from white to yellow, red, etc. Getting worse. A photosensitive lithographic printing plate with low safe light property is exposed to indoor lamps such as fluorescent lamps, resulting in a problem of deterioration in developability in which a residual film is formed in a non-image area during development processing, and also a problem of causing soiling during printing. On the other hand, the film strength of the image area is also affected, and there is also a problem that printing durability is deteriorated particularly in a highlight halftone image, a fine line image, a minute image, and the like.

  A generally known negative photosensitive lithographic printing plate utilizing photopolymerization utilizes a photopolymerization reaction of a monomer or polymer having an acrylate polymerizable double bond. In such an acrylate-based polymerization reaction, the presence of oxygen at the time of exposure significantly inhibits the polymerization reaction due to the exposure, so that sufficient image formation cannot be performed. Usually, an oxygen barrier layer (overlayer) made of a water-soluble resin such as polyvinyl alcohol or polyvinylpyrrolidone is provided. This is described, for example, in JP-A-8-137096, JP-A-9-160226, JP-A-9-236911, JP-A-2001-166488, and the like, which are described in the above-mentioned patent publications. A photosensitive lithographic printing plate for an infrared laser is similarly provided with an overlayer. Methods for improving the safe light property by containing an ultraviolet absorber or a red dye in the over layer are disclosed in Japanese Patent Application Laid-Open No. 2003-233192 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2004-252201 (Patent Document 2). Has been. However, due to the presence of such an over layer, there is a problem of image quality deterioration due to light scattering during laser exposure, and a pre-water washing step for removing the over layer is required prior to alkali development during development. In addition, there is a problem in that a step of applying an overlayer after applying the photosensitive layer is necessary in manufacturing.

  On the other hand, in JP-A-2001-290271, JP-A-2002-244288, and JP-A-2002-287340, a negative type using a photopolymerization reaction of a monomer or polymer having a phenyl group substituted with a vinyl group in the side chain. A photosensitive lithographic printing plate is described. Unlike the above acrylates, they do not have to have an overlayer, and have a high sensitivity enough to form a sufficient image. In particular, a photosensitive layer containing an organic boron salt as a photopolymerization initiator in the photosensitive layer. Sexual lithographic printing plates are very sensitive. However, the photosensitive lithographic printing plate is disadvantageous for safe light properties because of its high sensitivity, and a method of containing a hindered phenol compound and a hindered amine compound in the photosensitive layer is disclosed in JP-A-2006-39178 (Patent Document 3). However, the safelight property was not fully satisfactory.

On the other hand, the use of a tocopherol compound in a photosensitive lithographic printing plate is described in, for example, diazo compounds as described in JP-A-2-304568 (Patent Document 4) and JP-A-6-222554 (Patent Document 5). It is known as a technique that can improve the storage stability of a photosensitive lithographic printing plate having a resin.
JP 2003-233192 A Japanese Patent Laid-Open No. 2004-252201 JP 2006-39178 A JP-A-2-304568 JP-A-6-222554

  Accordingly, an object of the present invention is to provide a negative photosensitive lithographic printing plate having high safelight properties that does not cause the problem of smudges or poor printing durability during printing even when handled for a long time under a white fluorescent lamp. There is to do.

The above object of the present invention has been achieved by the following invention.
1) A negative photosensitive lithographic plate comprising a photosensitive layer containing a polymer containing a monomer having a polymerizable double bond in the side chain as a copolymerization component, a photopolymerization initiator, and a tocopherol compound on a support. Printed version.
2) The negative photosensitive lithographic printing plate according to 1), wherein the photosensitive layer further contains a hindered phenol compound.

  According to the present invention, it is a negative photosensitive lithographic printing plate having high safelight properties that can withstand long-time handling under a white fluorescent lamp.

  The present invention is a negative photosensitive lithographic printing plate having a photopolymerizable photosensitive layer, and the photosensitive layer includes a polymer containing a monomer having a polymerizable double bond in the side chain as a copolymerization component, a photopolymerization initiator. And a tocopherol compound.

[Polymer containing monomer having polymerizable double bond in side chain as copolymerization component]
The polymer containing a monomer having a polymerizable double bond in the side chain contained in the photosensitive layer of the photosensitive lithographic printing plate of the present invention as a copolymerization component (hereinafter referred to as a polymerizable double bond polymer) is polymerized in the side chain. Monomers having an ionic double bond (for example, 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, β-methoxyvinyl methacrylate, β-methoxyvinyl acrylate, vinylthioacrylate, vinylthiomethacrylate, etc.) as a copolymerization component, and Water-soluble group-containing monomers (for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene, 4-sulfostyrene, acrylonitrile, etc.) A polymer included as a copolymerization component is preferable.

  The polymerizable double bond polymer used in the present invention is particularly preferably a monomer having a phenyl group substituted with a vinyl group in the side chain and a carboxy group-containing monomer (for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic acid). Monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene and the like) (hereinafter referred to as vinylphenyl group-containing polymer). The monomer having a phenyl group substituted with a vinyl group in the side chain is a phenyl group substituted with a vinyl group bonded to the main chain directly or via a linking group, and the linking group is not particularly limited and is arbitrary. Or a linking group formed by combining them. Further, the phenyl group of the vinylphenyl group may have a substituent other than the vinyl group, for example, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group. It may be substituted with a group, an aryl group, an alkoxy group, an aryloxy group or the like. More specifically, the above-described vinylphenyl group-containing polymer has a group represented by the following general formula in the side chain.

In the formula, Z ₁ represents a linking group, and R ₁₁ , R ₁₂ and R ₁₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. An alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₁₄ represents a substitutable group or atom. n ₁ represents 0 or 1, m ₁ represents an integer of 0 to 4, and k ₁ represents an integer of ₁ to 4.

The above general formula will be described in more detail. As the linking group for Z ₁ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₁₅ ) —, —C (O) —O—, —C (R ₁₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following groups, alone or in combination of two or more. Here, R ₁₅ and R ₁₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

  Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole 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 ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring, and the like, and a substituent may be bonded to these heterocyclic rings. Examples of the group represented by the general formula are shown below, but are not limited to these examples.

Among the groups represented by the general formula, there are preferable ones. That is, it is preferable that R ₁₁ and R ₁₂ are hydrogen atoms and R ₁₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.). Furthermore, as the linking group for Z ₁ , those containing a heterocyclic ring are preferred, and those in which k ₁ is 1 or 2 are preferred.

  The vinylphenyl group-containing polymer contained in the photosensitive layer of the present invention is preferably an alkali-soluble polymer by introducing a carboxy group-containing monomer as described above. The proportion of the carboxy group-containing monomer contained in the vinylphenyl group-containing polymer is preferably 5% by mass or more and 99% by mass or less. If the proportion is less than this, the copolymer may not be dissolved in the alkaline aqueous solution. More preferably, the ratio of the carboxyl group-containing monomer contained in the copolymer composition is 10% by mass or more and 80% by mass or less, and particularly preferably 20% by mass or more and 70% by mass or less. The proportion of the monomer having a vinylphenyl group in the side chain contained in the copolymer composition is preferably 1% by mass to 95% by mass, more preferably 10% by mass to 80% by mass, 20 mass% or more and 75 mass% or less are especially preferable.

  As the carboxy group-containing monomer, acrylic acid, methacrylic acid, acrylic acid-2-carboxyethyl ester, methacrylic acid-2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid Examples include monoalkyl esters, 4-carboxystyrene and the like.

  The vinylphenyl group-containing polymer of the present invention may further contain another monomer as a copolymer component. Other monomers include styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, methyl methacrylate, Methacrylic acid alkyl esters such as ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate, aryl methacrylates such as phenyl methacrylate and benzyl methacrylate, or alkylaryl Esters, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monomethacrylate, methoxypolymethacrylate Methacrylic acid esters having an alkyleneoxy group such as lenglycol monoester, methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid esters such as methacrylic acid-2-dimethylaminoethyl, methacrylic acid-2-diethylaminoethyl, or Examples similar to these corresponding methacrylic acid esters as acrylic acid esters, vinylphosphonic acid or the like as a monomer having a phosphoric acid group, amino group-containing monomers such as allylamine or diallylamine, or vinylsulfonic acid and its salts Monosulfonic acid groups such as allylsulfonic acid and its salts, methallylsulfonic acid and its salts, styrenesulfonic acid and its salts, 2-acrylamido-2-methylpropanesulfonic acid and its salts Monomers, nitrogen-containing heterocycles such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole and N-vinylcarbazole, or 4-vinylbenzyltrimethylammonium chloride as a monomer having a quaternary ammonium base, Acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, etc., or acrylonitrile, methacrylate Ronitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropyl alcohol Acrylamide or methacrylamide derivatives such as rilamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, chloroacetic acid Vinyl esters such as vinyl, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, vinyl ethers such as methyl vinyl ether, butyl vinyl ether, and others, N-vinyl pyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride , Vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, glycidyl methacrylate, etc. Nomar, and the like.

  There is a preferred range for the molecular weight of the vinylphenyl group-containing polymer according to the present invention, and the weight average molecular weight is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 5,000 to 500,000.

  Examples of the vinylphenyl group-containing polymer having a group represented by the above general formula and having a carboxy group-containing monomer as a copolymerization component are shown below. In the formula, the number represents the mass% of each repeating unit in the copolymer total composition of 100 mass%.

[Photopolymerization initiator]
The photosensitive layer of the photosensitive lithographic printing plate of the present invention contains a photopolymerization initiator. Known compounds can be used as the photopolymerization initiator. For example, organic boron salts, trihaloalkyl-substituted compounds (for example, s-triazine compounds and oxadiazole derivatives, trihaloalkylsulfonyl compounds as trihaloalkyl-substituted nitrogen-containing heterocyclic compounds), hexaarylbisimidazoles, titanocene compounds, ketoximes Compounds, thio compounds, organic peroxides, onium salts (iodonium salts, diazonium salts, sulfonium salts described in JP-A-2003-114532) and the like. Among these photopolymerization initiators, organic boron salts are particularly preferred because of their high sensitivity. More preferably, a combination of an organic boron salt and a trihaloalkyl-substituted compound is used, resulting in higher sensitivity.

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

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, 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 ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is an alkyl group and the other substituent is an aryl group.

  Examples of the cation constituting the organic boron salt include alkali metal ions and onium compounds, but onium salts are preferred, for example, ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and triarylalkyls. Examples thereof include phosphonium salts such as phosphonium salts. Moreover, a cationic sensitizing dye may be used as the cation constituting the organic boron salt. Examples of particularly preferred organic boron salts are shown below.

  Other preferred photopolymerization initiators include trihaloalkyl-substituted compounds, and it is particularly preferable to combine a trihaloalkyl-substituted compound with an organic boron salt. The above-mentioned trihaloalkyl-substituted compound is specifically a compound having at least one trihaloalkyl group such as a trichloromethyl group or tribromomethyl group in the molecule. As a preferred example, the trihaloalkyl group is a nitrogen-containing compound. Examples of the compound bonded to the heterocyclic 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 heterocyclic ring via a sulfonyl group. It is done.

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

  The content of the photopolymerization initiator as described above 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 100% by mass of the polymerizable double bond polymer. preferable.

[Tocopherol compound]
When the photosensitive layer of the photosensitive lithographic printing plate which is a preferred embodiment of the present invention contains an organic boron salt as a photopolymerization initiator, the sensitivity of the photosensitive lithographic printing plate is increased, so that the safelight property is disadvantageous. Although the mechanism of action is not clear, it has been found that the inclusion of a tocopherol compound in the photosensitive layer of the photosensitive lithographic printing plate of the present invention is effective in improving the safelight properties of the lithographic printing plate.

  The tocopherol compound contained in the photosensitive layer of the photosensitive lithographic printing plate of the present invention is a tocopherol (α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol), a tocopherol derivative (for example, acetic acid-α-tocopherol, nicotinic acid-α -Tocopherol etc.) are included, and particularly preferred is tocopherol. The content of the tocopherol compound is preferably in the range of 0.01 to 50% by mass and more preferably in the range of 0.1 to 5% by mass with respect to 100% by mass of the polymerizable double bond polymer.

[Hindered phenol compounds]
By combining the tocopherol compound and the hindered phenol compound in the photosensitive layer of the photosensitive lithographic printing plate of the present invention, the photosensitive lithographic printing plate works extremely effectively for improving the safelight property of the photosensitive lithographic printing plate. A conventionally known compound can be used as the hindered phenol compound. For example, 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,2′-methylenebis (4-methyl-6- t-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] Methane, bis [3,3′-bis- (4′-hydroxy-3′-tert-butylphenyl) butyric acid] glycol ester, 2,6-di-tert-butyl-4-ethylphenol, 2,2 '-Methylenebis (4-ethyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, etc. The content of the hindered phenol compound is preferably in the range of 0.1 to 50% by mass and more preferably in the range of 0.5 to 10% by mass with respect to 100% by mass of the polymerizable double bond polymer. It is preferable that

[Sensitizing dye]
The photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably contains a sensitizing dye. The sensitizing dye sensitizes the decomposition of the photopolymerization initiator in a wavelength range of 380 nm to 1300 nm. Various cationic dyes, anionic dyes, and neutral dyes having no charge include merocyanine, coumarin, and xanthene. Thioxanthene, azo dyes and the like can be used. Among these, particularly preferable examples are dyes selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dyes as cationic dyes. It is. In combination with these cationic dyes, they are preferably used because of their particularly high sensitivity and excellent storage stability. Furthermore, in recent years, an output machine (plate setter) equipped with a violet semiconductor laser having an oscillation wavelength in the range of 380 to 410 nm has been developed. As a photosensitive system having high sensitivity corresponding to this output machine, a system containing a pyrylium compound or a thiopyrylium compound as a sensitizing dye is preferable. Examples of sensitizing dyes according to the present invention are shown below.

  Among the above sensitizing dyes, a system that gives light sensitivity to light in the near infrared to infrared wavelength region of 750 nm or more is particularly preferable, and it is necessary to have absorption in such a wavelength region as a sensitizing dye. There are particularly preferred examples used for such purposes.

  The sensitizing dye preferably used in the photosensitive layer of the photosensitive lithographic printing plate of the present invention is used so as to be compatible with the laser light source type of each image setter, but also in the spectral distribution (mainly 300 to 800 nm) of a white fluorescent lamp. In particular, when combined with an organic boron salt which is a preferred photopolymerization initiator of the present invention, it has a high sensitivity and is disadvantageous for safelight properties. However, by using the tocopherol compound of the present invention, the influence on the sensitivity is small and the safelight property can be improved. There is a preferred range in the quantitative ratio between the sensitizing dye and the photopolymerization initiator contained in the photosensitive layer of the present invention. The photopolymerization initiator is preferably used in the range of 0.01 to 100 parts by mass with respect to 1 part by mass of the sensitizing dye, and more preferably in the range of 0.1 to 50 parts by mass of the photopolymerization initiator. Is preferably used.

[Ethylenically unsaturated compound]
The photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably further contains an ethylenically unsaturated compound. By combining this, a higher sensitivity can be realized, and a lithographic printing plate excellent in printing performance can be obtained.

  Examples of the ethylenically unsaturated compound according to the present invention include polymerizable compounds having two or more polymerizable double bonds (for example, acrylate, methacrylate, etc.) in the molecule. Examples of ethylenically unsaturated compounds include polyfunctional monomers (eg, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanate). Nurate, tripropylene glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc.) and polyfunctional oligomers (polyester methacrylate, urethane methacrylate, epoxy methacrylate, etc.) ).

  A preferred embodiment of the ethylenically unsaturated compound includes a polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule. When this compound is used, crosslinking is effectively carried out by recombination of styryl radicals generated by the generated radicals, which is extremely preferable for producing a highly sensitive negative photosensitive lithographic printing plate. A polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule is typically represented by the following general formula.

In the formula, Z ₃ represents a linking group, and R ₃₁ , R ₃₂ and R ₃₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. An alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₃₄ represents a group or atom substitutable on the benzene ring. m ₃ represents an integer of 0 to 4, _{k 3} is an integer of 2 or more.

Further details will be described. As the linking group for Z ₃ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₃₅ ) —, —C (O) —O—, —C (R ₃₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₃₅ and R ₃₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

  Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole 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 ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring and the like, and a substituent may be bonded to these.

Among the compounds represented by the above general formula, there are preferable compounds. That is, R ₃₁ and R ₃₂ are hydrogen atoms, R ₃₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₃ is preferably a compound having 2 to 10. Specific examples of the polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule are shown below, but are not limited to these examples.

  There is a preferred range regarding the proportion of the ethylenically unsaturated compound as described above in the photosensitive composition, and the ethylenically unsaturated compound is 1 to 60 parts by mass in 100 parts by mass of the total photosensitive composition. It is preferably included in the range, and more preferably in the range of 5 to 50 parts by mass.

  As other elements constituting the photosensitive layer, hindered amine compounds described in JP-A Nos. 2002-244288 and 2006-39178 can be contained.

  Addition of a colorant can be preferably performed as another element constituting the photosensitive layer. The colorant is used for the purpose of enhancing the visibility of the image area after exposure and development processing, and includes various types such as carbon black, phthalocyanine dyes, triarylmethane dyes, anthraquinone dyes, and azo dyes. These pigments and pigments can be used, and can be preferably added in the range of 0.005 parts by mass to 0.5 parts by mass with respect to 1 part by mass of the polymerizable double bond polymer.

  Regarding the elements constituting the photosensitive layer, in addition to the elements described above, other elements may be added 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 or improving the sharpness of an image after development.

  Regarding the thickness of the photosensitive layer itself of the photosensitive lithographic printing plate of the present invention, it is preferably formed on the support with a dry thickness in the range of 0.5 μm to 10 μm, and more preferably in the range of 1 μm to 5 μm. This is extremely preferable for greatly improving the printability. For the photosensitive layer, a solution in which the above-described elements are mixed is prepared, and is applied onto a support and dried using various known coating methods. As the support, for example, a film or polyethylene-coated paper may be used, but a more preferable support is an aluminum plate that is polished and has an anodized film. Below, the processing method of an aluminum support body is demonstrated.

  The aluminum plate is usually grained to a more preferable shape. Examples of the graining method include mechanical graining (mechanical surface roughening), chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. In addition, electrochemical graining (electrochemical roughening, electrolytic graining), which is electrochemically grained in hydrochloric acid electrolyte or nitric acid electrolyte, or the aluminum surface is scratched with metal wire Mechanical graining methods (mechanical roughening treatment) such as brush grain method, ball grain method to grain the aluminum surface with abrasive balls and abrasives, brush grain method to grain the surface with nylon brush and abrasives, etc. Can be used. These graining methods can be used alone or in combination. For example, a combination of a mechanical surface roughening treatment with a nylon brush and an abrasive and an electrolytic surface roughening treatment with a hydrochloric acid electrolytic solution or a nitric acid electrolytic solution, or a combination of a plurality of electrolytic surface roughening treatments may be mentioned.

  In the case of the brush grain method, the long wavelength of the surface of the aluminum support is selected by appropriately selecting the conditions such as the average particle size, maximum particle size, bristle diameter of the brush used, density, indentation pressure, etc. The average depth of the component recesses can be controlled. The recesses obtained by the brush grain method preferably have an average wavelength of 3 to 15 μm and an average depth of 0.3 to 1 μm.

As the electrochemical surface roughening method, an electrochemical method in which graining is chemically performed in a hydrochloric acid electrolytic solution or a nitric acid electrolytic solution is preferable. A preferred current density is 50 to 400 C / dm ² in terms of electricity at the time of anode. More specifically, for example, in an electrolytic solution containing 0.1 to 50% by mass of hydrochloric acid or nitric acid, under conditions of a temperature of 20 to 100 ° C., a time of 1 second to 30 minutes, and a current density of 100 to 400 C / dm ² . This is done using direct current or alternating current. According to the electrolytic surface-roughening treatment, it is easy to impart fine irregularities to the surface, which is suitable for improving the adhesion between the photosensitive layer and the aluminum support.

  By electrochemical surface roughening after mechanical surface roughening, crater-like or honeycomb-like pits having an average diameter of about 0.3 to 1.5 μm and an average depth of 0.05 to 0.4 μm are formed on an aluminum plate. It can be made to produce on the surface of 80-100% of area ratio. In the case where only the electrochemical surface roughening method is performed without performing the mechanical surface roughening method, the average pit depth is preferably less than 0.3 μm. The provided pits have the effect of improving the resistance to stains on the non-image area of the printing plate and the printing durability. In the electrolytic surface roughening treatment, an amount of electricity necessary for providing sufficient pits on the surface, that is, the product of the current and the time during which the current flows is an important condition. From the viewpoint of energy saving, it is desirable that sufficient pits can be formed with a smaller amount of electricity. The surface roughness after the roughening treatment is such that the arithmetic average roughness (Ra) measured at a cut-off value of 0.8 mm and an evaluation length of 3.0 mm in accordance with JIS B0601-1994 is 0.2-0. It is preferably 8 μm.

  The grained aluminum plate is preferably subjected to chemical etching. As the chemical etching treatment, acid etching or alkali etching is known, and a chemical etching treatment using an alkaline solution is a particularly excellent method in terms of etching efficiency.

The alkali agent suitably used for the alkaline solution is not particularly limited, and examples thereof include sodium hydroxide, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, and lithium hydroxide. The alkaline etching treatment is preferably performed under such a condition that the amount of dissolved Al is 0.05 to 1.0 g / m ² . The other conditions are not particularly limited, but the alkali concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and the alkali temperature is 20 to 100 ° C. It is preferable that it is, and it is more preferable that it is 30-50 degreeC. The alkali etching treatment is not limited to one method, and a plurality of steps can be combined. In the present invention, an alkali etching treatment can be performed after the mechanical roughening treatment and before the electrochemical roughening treatment. In this case, the dissolution amount of Al is preferably 0.05 to 30 g / m ² .

  After performing the alkali etching treatment, pickling is performed to remove dirt (smut) remaining on the surface. Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. In particular, as a method for removing smut after the electrolytic surface roughening treatment, it is preferably brought into contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739. A method is mentioned.

  Moreover, when performing a chemical etching process with an acidic solution, the acid used for an acidic solution is not specifically limited, For example, a sulfuric acid, nitric acid, and hydrochloric acid are mentioned. The concentration of the acidic solution is preferably 1 to 50% by mass. Moreover, it is preferable that the temperature of an acidic solution is 20-80 degreeC.

  The aluminum plate treated as described above is further subjected to anodizing treatment. The anodizing treatment can be performed by a method conventionally used in this field. Specifically, when direct current or alternating current is applied to an aluminum plate in an aqueous solution or non-aqueous solution of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc., alone or in combination of two or more. An anodized film can be formed on the surface of the aluminum plate.

The conditions for the anodizing treatment vary depending on the electrolyte used, and thus cannot be determined unconditionally. In general, however, the electrolyte concentration is 1 to 80% by mass, the solution temperature is −5 to 70 ° C., and the current density is 0.8. 5 to 60 A / dm ² , voltage 1 to 100 V, and electrolysis time 10 to 200 seconds are appropriate. Among these anodizing treatments, the method of anodizing at a high current density in a sulfuric acid electrolyte solution described in British Patent 1,412,768 is particularly preferable.

In the present invention, the amount of anodized layer is preferably from 1 to 10 g / ^{m 2,} more preferably from 1.5~7g / ^{m 2,} particularly preferably from 2-5 g / ^{m 2} . After the roughening treatment, an alkali etching treatment can be performed before the electrochemical roughening treatment. In this case, the dissolution amount of Al is preferably 0.05 to 30 g / m ² .

  The photosensitive lithographic printing plate obtained by coating the photosensitive layer on the aluminum support produced as described above is subjected to laser scanning exposure according to the photosensitive area imparted to the photosensitive layer and exposed. Since the solubility in an alkaline developer is reduced due to crosslinking of the exposed portion, the pattern of the exposed image is formed by eluting the unexposed portion with an alkaline developer described later.

  A particularly preferable laser light source used for the laser scanning exposure according to the present invention is a laser having an oscillation wavelength in the near infrared region, and various semiconductor lasers, solid lasers such as YAG lasers and glass lasers are most preferable.

  The photosensitive layer of the present invention is coated on a support and dried using various known coating methods. Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, hopper coating, blade coating, and wire doctor coating.

  The alkaline developer used in the present invention preferably has a pH of 10 to 12 at 25 ° C. As an alkaline compound for adjusting the pH of the developer to the above range, sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethylethanolamine, triethylammonium hydroxide Of these, alkanolamines are particularly preferable. Furthermore, it is also preferable to add various alcohols such as ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin and benzyl alcohol to the alkaline developer. Also, various surfactants can be preferably added. After developing with such an alkaline developer, normal gumming is preferably performed using gum arabic, dextrins, and the like.

  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>
The following photosensitive layer coating solution is applied on a 0.24 mm thick aluminum plate that has been grained and anodized to a dry thickness of 3.5 μm, and dried with warm air at 75 ° C. And a photosensitive lithographic printing plate of the present invention and a comparison was obtained.

<Prescription of photosensitive layer coating solution of the present invention>
Polymerizable double bond polymer (P-1; weight average molecular weight of about 90,000) 10 parts by weight Photopolymerization initiator (described in Table 1) 2 parts by weight Photopolymerization initiator trihaloalkyl-substituted compound (T-4) 1 part by weight Increase Dye-sensitive dye (S-39) 0.4 parts by mass Ethylenically unsaturated compound (C-5) 2 parts by mass Hindered amine compound (Chemical formula 28) 1 part by mass 10% phthalocyanine dispersion 0.5 part by mass 1,4-dioxane 70 Part by mass Cyclohexanone 20 parts by mass Tocopherol compound (described in Table 1) 0.05 part by mass Hindered phenol compound (2,2′-methylenebis (4-methyl-6-tert-butylphenol) (described in Table 1) None or 0.5 Parts by mass

<Comparison of photosensitive layer coating solution>
Polymerizable double bond polymer (P-1; weight average molecular weight of about 90,000) 10 parts by weight Photopolymerization initiator (described in Table 1) 2 parts by weight Photopolymerization initiator trihaloalkyl-substituted compound (T-4) 1 part by weight Increase Dye-sensitive dye (S-39) 0.4 parts by mass Ethylenically unsaturated compound (C-5) 2 parts by mass Hindered amine compound (Chemical formula 28) 1 part by mass 10% phthalocyanine dispersion 0.5 part by mass 1,4-dioxane 70 Parts by mass cyclohexanone 20 parts by mass radical scavenger (described in Table 1) None or 0.05 parts by mass hindered phenol compound (2,2′-methylenebis (4-methyl-6-tert-butylphenol) (described in Table 1) None or 0.5 parts by weight

  The present invention and the comparative photosensitive lithographic printing plate are exposed for 2 hours with a white fluorescent lamp (white fluorescent lamp FLR40SW / M / 36 manufactured by Mitsubishi Electric Corporation) so that the plate surface becomes 500 lux, and the present invention and Safelight exposed and unexposed samples were obtained for each comparative photosensitive lithographic printing plate.

<Appropriate exposure energy amount>
The above comparison and the photosensitive lithographic printing plate of the present invention (safelight unexposed sample) were subjected to drum rotation speed using PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd. At 400 rpm, laser exposure (1200 dpi, 100 lines) is performed while changing the exposure energy amount every 20 mJ / cm ² , and the exposed plate is developed with a developing solution described later. The exposure energy amount that is within 2% was determined as the appropriate exposure energy amount (mJ / cm ² ) of each sample and listed in Table 1.

<Laser exposure>
The sample obtained by the exposure of the above white fluorescent lamp, and further the safelight unexposed sample are exposed (1200 dpi, 100 lines) with the appropriate exposure energy amount determined above, and the exposed plate is subjected to the development processing described later. Made a plate.

<Development processing>
The development processing method uses an automatic developing machine PD-1310 for PS plate manufactured by Dainippon Screen Mfg. Co., Ltd. as an automatic developing machine, and develops using a developer having the following formulation (developing temperature 28 ° C., developing time 20 Second treatment), followed by washing with water, applying a gum solution having the following formulation, and drying to obtain a printing plate.

<Developer>
N-ethylethanolamine 37g
85 g of phosphoric acid aqueous solution 10 g
60% of 25% by weight tetramethylammonium hydroxide aqueous solution
35% by weight of sodium alkylnaphthalenesulfonate aqueous solution 30g
EDTA2 sodium 1g
1L with water
pH = 11.20

<Gum solution>
Monopotassium phosphate 5g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2 sodium 1g
1L with water

<Non-image area developability test>
The non-image area of the printing plate obtained by the development process was observed with a magnifying glass (50 times magnification), and the remaining film of the non-image area was evaluated according to the following criteria. In addition, developability is so good that the numerical value of evaluation criteria is large. The results are shown in Table 1.
<Non-image area developability evaluation criteria>
3: There is no residual film in the non-image area. 2: A residual film exists in the form of dots in the non-image area. 1: A residual film exists on almost the entire surface of the non-image area.

<Print stain test>
The printing plate obtained by the above development processing is mounted on a printing machine Ryobi 560, using 1% Toho Etch aqueous solution manufactured by Toho Seiki as a moisturizing liquid, and Dainippon Ink & Chemicals F gloss purple (soft type) as ink. 1000 sheets of white coated paper were printed (the 1000th sheet was sampled). The conditions during printing were an indoor temperature of 23 ° C. and a relative humidity of 65%. The sampled printed matter was visually observed, and the background stain on the non-image area was evaluated according to the following criteria. Note that the greater the numerical value of the evaluation standard, the better the soiling. The results are shown in Table 1.
<Evaluation criteria for dirt>
3: There is no background stain in the non-image area 2: There is a slight background contamination in the non-image area 1: There is significant background contamination in the non-image area

<Printing durability test>
The printing plate obtained by the above development processing is mounted on a printing press Ryobi 560, white coated paper using a 10% isopropyl alcohol aqueous solution as a moisturizing liquid, and F gloss ink (hard type) manufactured by Dainippon Ink and Chemicals as an ink. Printed 100,000 sheets (sampling the 100,000th sheet). The conditions during printing were an indoor temperature of 23 ° C. and a relative humidity of 65%. A 1% halftone dot image of the sampled printed matter was observed with a magnifying glass (50 times magnification), and printing durability was evaluated according to the following criteria. The larger the evaluation standard value, the better the printing durability. The results are shown in Table 1.
<Evaluation criteria for printing durability>
3: 1% halftone dot images all remain 2: 1% halftone dot images are partially missing 1: 1% halftone dot images are mostly missing

  From the results shown in Table 1, the photosensitive lithographic printing plate is exposed to a white fluorescent lamp for a long time, so that the comparative photosensitive lithographic printing plate significantly deteriorates the development processability and printing characteristics. It can be seen that the lithographic printing plate has very little influence on the development processability and printing characteristics and is excellent in safe light properties.

Claims (2)

  A negative photosensitive lithographic printing plate having a photosensitive layer containing a polymer containing a monomer having a polymerizable double bond in the side chain as a copolymerization component, a photopolymerization initiator, and a tocopherol compound on a support. .   The negative photosensitive lithographic printing plate according to claim 1, wherein the photosensitive layer further contains a hindered phenol compound.