JP4813942B2 - Photosensitive composition and planographic printing plate using the same - Google Patents

Description

  The present invention relates to a photosensitive composition, and further to a lithographic printing plate precursor using the same. More specifically, the present invention relates to a negative photosensitive composition and a negative photosensitive lithographic printing plate capable of forming an image by ultraviolet or infrared laser irradiation.

  Conventionally, as a negative photosensitive composition or a negative photosensitive lithographic printing plate, a diazo resin salt and an alkali-soluble resin such as an acrylic resin or a polyurethane resin are used as main photosensitive layer components, and an exposed portion is exposed by ultraviolet exposure. Is photocured and the solubility in a developing solution is reduced, and unexposed areas are developed and dissolved to remove non-images so that the exposed areas are images. Usually, both conventional negative PS plates It is called.

  In addition, a high-sensitivity photosensitive composition that can be directly drawn by a laser and capable of making a plate has also been developed, and is composed of a photopolymerization initiator, a dye sensitizer, and a polymerizable compound, and is a photopolymer-based photosensitive that can be made by an argon laser (488 nm). Active compositions have been put to practical use.

  In recent years, high-power semiconductor lasers, YAG lasers, and the like that emit light in the region of 750 nm or more have been used as light sources. For example, Patent Document 1 discloses a resole resin, a novolak resin, a latent bronstec acid, and an infrared ray. A lithographic printing plate comprising an absorbent is disclosed. In this system, the light absorbed by the infrared absorber is converted into heat, and the generated heat decomposes the thermal acid generator to generate an acid. In the subsequent heating step (preheating), the generated acid is converted into a resole resin. It is cured to reduce the solubility in a developing solution to obtain an image. However, the non-image area is easily soiled and poorly developed due to preheating, and inefficiency and uneconomical related to heating are major problems.

  The photopolymerization (photopolymer) -based photosensitive composition sensitive in the above wavelength region is disclosed in Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and the like. Each of the photopolymerization type photosensitive compositions disclosed therein comprises an infrared absorber, a photopolymerization initiator, an ethylenically unsaturated compound, and a binder resin. Polyvinyl alcohol or the like is used on the photosensitive layer. A protective layer (overcoat layer) was provided. Since this overcoat layer is mainly water-soluble, the plates may block each other in a high-humidity atmosphere, and pre-washing for removing the overcoat layer may be necessary during development. When a printing plate is produced, there is an inconvenience in production such that an overcoat layer must be further applied after the photosensitive layer is applied.

As a photosensitive composition that does not require such an overcoat layer, a polymer having a phenyl group substituted with a vinyl group in the side chain, a photo radical generator, and absorption in the wavelength region from visible light to infrared light. Patent Document 6 discloses a photosensitive composition containing a sensitizer for sensitizing the photo radical generator. The polymer in the photosensitive composition is easily gelled as the polymer is polymerized, and cannot be made into a high polymer. As a result, a strong film cannot be formed, and the photosensitive layer is easily scratched. There was a problem.
Japanese Patent Laid-Open No. 7-20629 Japanese Unexamined Patent Publication No. 2000-122273 JP 2000-122274 A Japanese Patent Laid-Open No. 2000-131833 JP 2000-131837 A JP 2001-290271 A

Further, the photosensitive composition that does not require the overcoat layer may cause fogging due to leakage light or increase the output so that the exposure amount is about 100 mj / cm ² or more, or focus for positioning the plate. There was a problem that light fogging caused by laser light (light near 650 nm) occurred and streaky residual film residue (referred to as banding) was generated during development, causing stains.
In order to solve the above-mentioned problems, the present inventors have previously proposed a photosensitive composition containing a copolymer containing the monomer represented by the general formula (II) (Japanese Patent Application No. 2006-008129) and the above-mentioned A photosensitive composition containing a copolymer composed of a monomer represented by the general formula (II) and a styrene compound has been proposed, but a photosensitive composition having higher printing durability has been found and the present invention has been achieved. Is.

  Accordingly, an object of the present invention relates to a negative photosensitive composition that can be developed with an aqueous alkaline solution after irradiation with ultraviolet light or irradiation with a solid laser or semiconductor laser having an oscillation wavelength in the near infrared to infrared region, Providing a photosensitive composition and a lithographic printing plate that have no sensitivity variation, excellent adhesion to the support and scratch resistance, no banding phenomenon, high printing durability, and no need for an overcoat layer To do.

  That is, according to the present invention, it contains a copolymer having a monomer unit represented by the following general formulas (I) and (II), a polymerizable compound, a polymerization initiator, and an infrared absorber. And a lithographic printing original plate provided with the photosensitive composition on a support.

(In the formula, R ¹ represents a hydrogen atom or a cyano group, and m represents 0 or 1.)

  As will be described in detail below, the lithographic printing plate provided with the photosensitive composition according to the present invention does not require an overcoat layer, and is subjected to an alkali development similar to a conventional PS plate after UV exposure or laser exposure. It can be developed with a liquid, there is no deposit on the surface of the photosensitive layer, it does not stain the setter during exposure, there is no variation in sensitivity, it has excellent adhesion to the support and scratch resistance, and banding phenomenon Therefore, a printing plate having high printing durability can be obtained.

  Embodiments of the present invention will be described below. However, the embodiments described below do not limit the present invention. The copolymer according to the present invention includes a dicyclopentenyloxyethyl methacrylate represented by the following formula (I ′) and a monomer represented by the following general formula (II ′) as described in detail below. It may be a copolymer obtained by adding other monomers having an unsaturated bond group that can be polymerized to these components and other monomers having a carboxyl group or a hydroxyl group, if necessary, An alkali-soluble copolymer is preferable.

(In the formula, R ¹ represents a hydrogen atom or a cyano group, and m represents 0 or 1.)

  The blending ratio of the dicyclopentenyloxyethyl methacrylate represented by the formula (I ′) in the copolymer according to the present invention is 5 to 40% by weight, more preferably 10 to 30% by weight. When the content is 5% by weight or more, particularly 10% by weight or more, the aqueous solution becomes stable with respect to the alkaline aqueous solution used as a developer, and a strong image can be obtained when an image is formed. 40% by weight or less, particularly 30% by weight or less, is preferable because it is easy to dissolve in an alkaline aqueous solution and the development speed is not increased and the sensitivity is not decreased.

  The blending ratio of the vinyl cinnamate represented by the formula (II ′) or the derivative thereof or cinnamylidene vinyl acetate or the derivative thereof in the copolymer is 20 to 70% by weight, more preferably 30 to 60% by weight. . When the amount is 20% by weight or more, particularly 30% by weight or more, the sensitivity does not become slow and a tough image can be obtained, and when it is 70% by weight or less, particularly 60% by weight or less, light or heat fogging occurs. It is preferable because it can be easily handled indoors.

In the above copolymer, in addition to the dicyclopentenyloxyethyl methacrylate represented by the formula (I ′) and the monomer (monomer) represented by the formula (II ′), other polymerizable components may be added as necessary. As the monomer (monomer), for example, monomers listed in the following (1) to (9) are preferable.
(1) A monomer having an aromatic hydroxyl group. For example, N- (p-hydroxyphenyl) acrylamide, N- (p-hydroxyphenyl) methacrylamide, p-isopropenylphenol, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, o-hydroxyphenyl Acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxyphenyl methacrylate, N- (p-hydroxyphenyl) maleimide and the like can be mentioned.
(2) A monomer having an aliphatic hydroxyl group. Examples thereof include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxypropyl methacrylate and the like.
(3) α, β-unsaturated carboxylic acid. For example, acrylic acid, methacrylic acid, maleic anhydride and the like can be mentioned.
(4) (Substituted) alkyl acrylate. For example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, glycidyl acrylate, benzyl acrylate, ethyl phenylcarbamate acrylate -G and the like. In the present specification, “(substituted)” means “substituted or unsubstituted”.
(5) (Substituted) alkyl methacrylate. For example, methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, amylmethacrylate, benzylmethacrylate, phenylmethacrylate, cyclohexylmethacrylate, Examples thereof include glycidyl methacrylate and ethyl phenylcarbamate.
(6) Acrylamide or methacrylamide. For example, acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, etc. Can be mentioned.
(7) Urethane (meth) acrylate. For example, polyether type urethane (meth) acrylate, polyester type urethane (meth) acrylate and the like can be mentioned.
(8) Styrenes. For example, styrene, α-methylstyrene, chloromethylstyrene and the like.
(9) N-vinyl pyrrolidone, N-vinyl carbazole, N-vinyl pyridine, acrylonitrile, methacrylonitrile and the like.
These may be used singly or in combination of two or more of the same group of compounds (1) to (9), or may be used in combination of two or more of different groups of compounds.

  There is no restriction | limiting in particular about the manufacturing method of the said copolymer, It can manufacture similarly to the manufacturing method of a normal vinyl type or acrylic type copolymer. For example, a desired copolymer can be obtained by dissolving each monomer component in a suitable solvent, adding a conventionally used radical polymerization initiator, and performing polymerization by heating as necessary. The copolymer thus obtained has a polystyrene calculated weight average molecular weight of 10,000 to 200,000, preferably 20,000 to 150,000, as measured by gel permeation chromatography (GPC). . If the weight average molecular weight is less than 10,000, the image portion is likely to swell and the mechanical strength is insufficient. If it exceeds 200,000, it is not preferable because stains due to poor development are likely to occur.

  Examples of the solvent used for the polymerization of the copolymer include methyl cellosolve, propylene glycol monomethyl ether, dioxane, methyl ethyl ketone, cyclohexanone, N, N-dimethylformamide and the like. Examples of the radical polymerization initiator used for the polymerization of the copolymer include 2,2'-azobis (2-methylbutyronitrile), benzoyl peroxide, and the like. The addition amount is 0.1 to 1.0% by weight based on the total amount of monomers.

  When the photosensitive composition of the present invention is used as a photosensitive layer, the content of the copolymer in the photosensitive layer is usually 20 to 95% by weight, preferably 30 to 90% by weight. If it is 20% by weight or more, the printing durability will not be deteriorated, and if it is 95% by weight or less, development defects and stability over time will not be deteriorated.

  The said copolymer used for this invention may be used independently, and may use 2 or more types together. Moreover, the said copolymer in this invention can also be mixed and used with another conventionally well-known binder polymer in the range which does not impair an effect.

  The polymerizable compound used in the present invention may be a general radical polymerizable monomer, a polyfunctional monomer having two or more ethylenic double bonds capable of addition polymerization in the molecule, or a polyfunctional oligomer. it can. The compound is not limited, but preferred examples include 2-ethylhexyl acrylate, 2-hydroxypropyl acrylate, glycerol acrylate, tetrahydrofuryl acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate, tetrahydrofurfuryloxy acrylate, 1,3 -Acrylate of ε-caprolactone adduct of dioxane alcohol, short functional acrylic ester such as 1,3-dioxolane acrylate, or methacrylic acid, itaconic acid in which these acrylates are replaced with methacrylate, itaconate, clonate, maleate, Crotonic acid, maleic acid esters such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol Acrylate, pentaerythritol diacrylate, hydroquinone diacrylate, resorcin diacrylate, hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, tricyclodecane dimethylol acrylate, 1,6-hexanediol diglycidyl ether Difunctional acrylates such as diacrylates, or methacrylic acid, itaconic acid, crotonic acid, maleic acid esters such as trimethylolpropane triacrylate, ditrileate in which these acrylates are replaced with methacrylate, itaconate, clonate, maleate Methylolpropane tetraacrylate, trimethylolethane triacrylate, pentaerythritol triacrylate, Intererythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ε-caprolactone adduct of dipentaerythritol hexaacrylate, pyrogallol triacrylate, propionic acid / dipentaerythritol triacrylate, propionic acid / dipentaerythritol tetraacrylate , Polyfunctional acrylic esters such as ethoxylated isocyanuric acid triacrylate, or methacrylic acid, itaconic acid, crotonic acid, maleic acid ester, etc. in which these acrylates are replaced by methacrylate, itaconate, clonate, maleate, etc. Can do.

  Prepolymers can also be used as described above. Examples of the prepolymer include compounds as described below. Moreover, the prepolymer which introduce | transduced acrylic acid or methacrylic acid to the oligomer of a suitable molecular weight, and provided photopolymerizability can also be used conveniently. These prepolymers may be used alone or in combination of two or more, and may be used in admixture with the aforementioned monomers and / or oligomers.

  Examples of prepolymers include adipic acid, trimellitic acid, maleic acid, phthalic acid, terephthalic acid, malonic acid, succinic acid, glutaric acid, itaconic acid, pyromellitic acid, fumaric acid, dodecanoic acid, and tetrahydrophthalic acid. Basic acid, ethylene glycol, propylene glycol, diethylene glycol, propylene oxide, 1,4-butanediol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, 1,6- Polyester acrylates in which (meth) acrylic acid is introduced into a polyester obtained by combining a polyhydric alcohol such as hexanediol, such as bisphenol A, epichlorohydrin, (meth) acrylic acid, Epoxy acrylates in which (meth) acrylic acid is introduced into an epoxy resin such as ernovolak, epichlorohydrin, (meth) acrylic acid, such as ethylene glycol-adipic acid, tolylene diisocyanate, 2-hydroxyethyl acrylate, polyethylene glycol, tolylene Isocyanate, 2-hydroxyethyl acrylate, hydroxyethylphthalyl methacrylate, xylene diisocyanate, 1,2-polybutadiene glycol, tolylene diisocyanate, 2-hydroxyethyl acrylate, trimethylolpropane, propylene glycol, tolylene diisocyanate, 2-hydroxyethyl Like acrylate, urethane acrylate in which (meth) acrylic acid is introduced into urethane resin, such as poly Loki San acrylate, silicone resin acrylate such as polysiloxane Diisocyanate 2-hydroxyethyl acrylate, other, include the oil-modified alkyd resin (meth) prepolymer alkyd-modified acrylates obtained by introducing an acryloyl group.

  As another preferred example of the polymerizable compound, two or more phenyl groups substituted with vinyl groups in the molecule represented by the following general formula (IV) as described in JP-A-2001-290271 are used. The polyfunctional styrene crosslinking agent which has is mentioned.

In the general formula (IV), Z represents a linking group, and R ²¹ , R ²² and R ²³ each independently represent a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group. A group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, etc., and these groups are substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, and the like. Also good. R ²⁴ represents a substitutable group or atom. h represents an integer of 0 to 4, and k represents an integer of 2 or more.

Here, examples of the linking group represented by Z, an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene ^{group, -N (R 4) -,} - C (O) -O -, - C (R 5 ) = N—, —C (O) —, a sulfonyl group, a heterocyclic structure, and a benzene ring structure, or a group in which two or more are combined. Here, R ⁴ and R ⁵ 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 structure constituting the linking group represented by Z 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, benztriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrazine ring, triazine ring, Examples include nitrogen-containing heterocycles such as quinoline ring and quinoxaline ring, furan ring, and thiophene ring. These heterocyclic structures are further alkyl groups, amino groups, aryl groups, alkenyl groups, carboxy groups, sulfo groups, and hydroxy groups. Have substituents such as It may be.

Examples of the substitutable group or atom represented by R ²⁴ 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 alkoxy group, and an aryloxy group. Further, these groups or atoms may have a substituent such as an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, or a hydroxy group.

Among the compounds represented by the general formula (IV), those having the structure shown below are preferable. That is, R ²¹ and R ²² in the general formula (IV) are hydrogen atoms, R ²³ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and K is an integer of 2-10. Is preferred.
Specific examples (M-1) to (M-7) of the compound represented by the general formula (IV) are shown below, but are not limited to these specific examples.

  In the present invention, these monomers can be used in a chemical form such as a prepolymer, that is, a dimer, a trimer and an oligomer, or a mixture thereof and a copolymer thereof.

  The amount of the polymerizable compound used is preferably 1 to 90% based on the weight of the total solid content of the photosensitive composition, from the viewpoint of film formation, printing durability, and storage stability. Preferably it is 5 to 80%, More preferably, it is 10 to 70%.

  Examples of the polymerization initiator used in the present invention include (a) an organophosphorus compound such as (a) bis (p-aminophenol-unsaturated) ketone, (b) triphenylphosphine or a phosphonium salt, and (c) a mercapto derivative. , (D) tetrazonium derivatives, (e) imidazoles, (f) carbonyl compounds, (g) peroxides, (h) halogenated compounds, (i) organic boron salts, (j) sensitizing dyes, and the like. In particular, an organic boron salt is preferably contained. Specific examples of the above (a) to (j) are given below, but the present invention is not limited to these.

  Examples of the (a) bis (p-aminophenol-unsaturated) ketone include 2,6-bis (4′-dimethylaminobenzylidene) cyclohexanone, 2,5-bis (4′-dimethylaminobenzylidene) cyclopenta Non, 2,5-bis (4′-diethylaminobenzylidene) cyclopentanone, 2,6-bis (4′-diethylamino-2′-methylbenzylidene) cyclohexane, 2,5-bis (4′-diethyl-2 ′) -Methylbenzylidene) cyclopentanone and the like.

  Examples of the organophosphorus compounds (b) include triphenyl phosphine, allyl triphenyl phosphonium bromide, allyl triphenyl phosphonium chloride, n-amyl triphenyl phosphonium chloride, benzyl triphenyl phosphonium. Examples include chloride, bromomethyltriphenylphosphonium bromide, and n-butyltriphenylphosphonium bromide.

  Examples of the (c) mercapto derivative include 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and the like.

  Examples of the (d) tetrazonium derivative include 2,3-diphenyl-5- (p-diphenyl) tetrazonium chloride, 2,5-diphenyl-3- (p-diphenyl) tetrazonium chloride, 2,3 -Diphenyl-5-ethyltetrazonium chloride, 2,3-diphenyl-5- (m-hydroxyphenyl) tetrazonium chloride, 2,3-diphenyl-5- (p-methoxyphenyl) tetrazonium chloride, 2 , 3-Diphenyl-5-methoxytetrazonium chloride, 2,5-diphenyl-3- (p-phenylazophenyl) tetrazonium chloride, 2,3-diphenyl-3- (4-styrylphenyl) tetrazonium Chloride, 2,3-diphenyl-5- (p-tolyl) tetrazonium chloride, 2,3 Diphenyl-3- (4-trimethylammonium-indole) phenyl tetrazolium chloride and the like.

  Examples of (e) imidazoles include hexaarylbisimidazole, 2- (2-chlorophenyl) -4, 5-diphenylimidazole dimer, 2- (2,3-dichlorophenyl) -4, 5-diphenylimidazole dimer. And 2- (2-chlorophenyl) -4,5-bis (4-methoxyphenyl) imidazole dimer.

  Examples of the carbonyl compounds (f) include benzoin, benzoin isopropyl ether, benzyldimethyl ketal, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 1-hydroxycyclohexylphenyl. Ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino propane, and the like.

  Examples of the above (g) peroxide include di-t-butyl peroxide, benzoyl peroxide, succinic acid peroxide, 1,3-di (t-butyldioxycarbonyl) benzene, 3,3 ′, 4. , 4′-tetrakis (t-butyldioxycarbonyl) benzophenone and the like.

  Examples of the halogenated compound (h) include 2,4,6-tri (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2-naphthyl- Examples include 4,6-bis (trichloromethyl) -s-triazine.

  The (i) organic boron salt serves as a radical generator when irradiated with near-infrared rays or infrared rays, and polymerizes a polymerizable compound. In particular, when a resin having a double bond group is present, the organoboron salt has a higher molecular weight by entangled a polymerizable compound with the group. Thereby, the film strength is improved, the sensitivity is high, the adhesiveness with the support is excellent, and the printing durability is improved. As the organic boron salt, an organic boron anion-counter cation complex is preferably used. Examples of the organic boron anion include those described in JP-A-62-143044, JP-A-9-188585, JP-A-9-188686, JP-A-9-188710, and the like. Methyl-diphenylboron anion, n-butyl-triphenylboron anion, n-butyl-trinaphthylboron anion, n-butyl-tri (p-methoxyphenyl) boron anion, n-butyl-tri (t-butylphenyl) boron An anion, an ethyl-tri (1-naphthyl) boron anion, etc. are preferable. Examples of the counter cation include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts.

  Examples of the sensitizing dye (j) include xanthene dyes, merocyanine dyes, coumarins, and ketocoumarin dyes.

  The said polymerization initiator in this invention may use only 1 type, and may use 2 or more types together. The polymerization initiator in the photosensitive composition of the present invention is preferably added in an amount of 0.01 to 50% by weight, preferably 0.1 to 40% by weight, based on the total solid content. When the addition amount is 0.01% by weight or more, the sensitivity becomes faster, and when it is 50% by weight or less, the developability of the non-image area is further improved, which is preferable.

  The infrared absorbent used in the present invention has a function of converting absorbed infrared light into heat and a function of generating excited electrons, and is a dye or pigment having an absorption maximum from a wavelength of 760 nm to 1200 nm.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include azo dyes, metal complex dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium dyes, and metal thiolate complex dyes. It is done.

  As the pigment used in the present invention, commercially available pigments and pigments described in the Color Index Handbook, “Latest Pigment Handbook” (edited by the Japan Pigment Technical Association, published in 1977) and the like can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, Kinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used.

  From the viewpoint of uniformity in the photosensitive composition and durability as an image area when applied to a negative recording layer, the amount of these infrared absorbers added is based on the total solid content contained in the photosensitive composition. 0.01 to 50% by weight, preferably 0.1 to 40% by weight. When the addition amount is 0.01% by weight or more, the sensitivity becomes faster, and when it is 50% by weight or less, the developability of the non-image area is further improved, which is preferable.

  In addition to the above essential components, other components suitable for the application, production method and the like can be appropriately added to the photosensitive composition of the present invention. Hereinafter, it illustrates about a preferable other component.

[Polymerization inhibitor]
In the photosensitive composition of the present invention, in order to prevent unnecessary thermal polymerization of a polymerizable compound having an ethylenically unsaturated double bond, that is, a polymerizable compound, during production or storage of the photosensitive composition. It is desirable to add a small amount of a thermal polymerization inhibitor. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01 wt% to about 5 wt% with respect to the weight of the total solid content in the entire composition.
In addition, when the photosensitive composition of the present invention is applied to a lithographic printing plate precursor, a higher fatty acid derivative such as behenic acid or behenic acid amide is added as necessary to prevent polymerization inhibition by oxygen. Then, it may be unevenly distributed on the surface of the negative recording layer in the course of drying after coating. The amount of the higher fatty acid derivative added is preferably about 0.5 wt% to about 10 wt% with respect to the total solid content in the total composition.

[Colorant]
Further, a dye or pigment may be added to the photosensitive composition of the present invention for the purpose of coloring. As a result, when the photosensitive composition of the present invention is applied to a lithographic printing original plate, it is possible to improve so-called plate inspection properties such as visibility after plate making as a printing plate and image density measuring instrument suitability. As the colorant, it is preferable to use a pigment or a dye. Examples of the pigment include phthalocyanine pigments, azo pigments, carbon black, and titanium oxide. As the dye, a leuco pigment, an oil-soluble dye, or a basic dye is preferable. Specifically, Crystal Violet, Malachite Green, Victoria Bull, Methylene Blue, Ethyl Violet, Rhodamine B, Victoria Pure Blue BOH (Hodogaya Chemical Industries), Oil Blue 613 (Orient Chemical Industries), Oil Green Etc. are preferred. The amount of the pigment or dye added as the colorant is preferably about 0.5 to about 50% by mass with respect to the total solid content of the photosensitive composition. When the amount is 0.5% by mass or more, the image forming layer is sufficiently colored and the image can be easily seen. When the amount is 50% by mass or less, a colorant residue hardly remains in a non-image area after development.

[Other additives]
Depending on the purpose, the photosensitive composition of the present invention further includes an oxygen scavenger such as phosphine, phosphonate, phosphite, a reducing agent, an anti-fading agent, a surfactant, a plasticizer, an antioxidant, an ultraviolet absorber, a protective agent. A glaze, an antistatic agent, and other additives imparting various characteristics may be mixed with a diluting solvent or the like.

Further, it can improve the ink deposition property on the surface of the negative recording layer when the inorganic filler for improving the physical properties of the cured film, other plasticizers, and the photosensitive composition of the present invention are applied to the lithographic printing plate precursor. You may add well-known additives, such as a fat-sensitizing agent.
Examples of the plasticizer include butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

<Lithographic printing plate>
The lithographic printing original plate of the present invention is characterized by having a negative recording layer (photosensitive layer) containing the photosensitive composition of the present invention on a support. Moreover, you may further have other layers, such as an intermediate | middle layer (undercoat layer) or an overcoat layer, as needed.

  Improves detachability between plates when a large number of lithographic printing original plates of the present invention are stacked without interleaving paper, and also improves detachability between interleaving paper and plate even when interleaving interleaving paper Therefore, the surface of the photosensitive layer of the lithographic printing original plate may be matted. As a method for matting the surface of the photosensitive layer, a method of adding a matting agent or the like to the photosensitive composition of the present invention, a solution in which a water-soluble resin or a water-soluble resin and a matting agent are dissolved and dispersed on the surface of the photosensitive layer. There are methods such as spray coating. Examples of the matting agent include silicon dioxide, zinc oxide, titanium oxide, alumina powder, starch, starch, polymer particles (for example, particles such as polyacrylic acid and polystyrene), and the like.

  Although not particularly limited, a photosensitive layer in which the above components are dissolved in a solvent is applied onto a support to provide a photosensitive layer, whereby a lithographic printing plate precursor can be produced.

  Examples of the solvent include methanol, ethanol, propanol, methylene chloride, ethyl acetate, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, dimethylformamide, dimethyl Examples thereof include, but are not limited to, sulfoxide, dioxane, dioxolane, acetone, cyclohexanone, trichloroethylene, and methyl ethyl ketone. These solvents can be used alone or in admixture of two or more. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.

Various methods can be used as the coating method, and examples thereof include spin coating, extrusion coating, bar coater coating, roll coating, air knife coating, dip coating, and curtain coating. The coating amount of the photosensitive layer varies depending on the use, but is preferably 0.5 to 5.0 g / m ² at the time of drying.

  Examples of the support include a metal plate such as aluminum, zinc, copper, or steel, a metal plate plated or vapor-deposited with chromium, zinc, copper, nickel, aluminum, iron, or the like, paper, plastic film, or glass. Examples thereof include a plate, paper coated with a resin, and a plastic film subjected to a hydrophilic treatment.

  As the support of the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Thus, the composition of the aluminum plate applied to the present invention is not specified, and a conventionally known and publicly available aluminum plate can be appropriately used. The thickness of the aluminum plate used in the present invention is approximately 0.1 to 0.5 mm, preferably 0.12 to 0.4 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant or an alkaline aqueous solution is performed to remove the rolling oil on the surface. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically roughening the surface, and a method of selectively dissolving the surface chemically. By the method. As the mechanical method, known methods such as brush polishing, ball polishing, blast polishing, and buff polishing can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, a method combining a mechanical method and an electrochemical method disclosed in JP-A-53-123204 can also be used. The roughened aluminum plate is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodization treatment to enhance the water retention and wear resistance of the surface as desired. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used as an electrolyte used for anodizing the aluminum plate.

The treatment conditions for anodization vary depending on the electrolyte used and cannot be specified. However, in general, the concentration of the electrolyte is 1 to 60% by weight, the liquid temperature is 5 to 60 ° C., and the current density is 2 to 50 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 5 seconds to 3 minutes are suitable. If the amount of anodic oxide film is 0.5 to 5.0 g / m ² is appropriate, small and wear resistance becomes worse than 0.5 g / m ^2, When it is 5.0 g / m ² or more, the anodic oxidation It is not preferable because a dye or the like easily penetrates into the holes.

  After the anodization, the aluminum plate is further subjected to a chemical conversion treatment with, for example, an alkali silicate, sodium phosphate, sodium fluoride, zirconium fluoride, alkyl titanate, trihydroxybenzoic acid alone or in a mixed solution, Sealing treatment by immersion in aqueous solution or steam bath, chemical conversion or coating treatment with aqueous solution of strontium acetate, zinc acetate, magnesium acetate or calcium benzoate, polyvinylpyrrolidone, polyaminesulfonic acid, polyvinylphosphonic acid, polyacrylic Chemical conversion or coating treatment with acid, polymethacrylic acid or the like can also be performed as a post-treatment.

  Furthermore, as the above-mentioned support, an aluminum support subjected to the surface treatment described in JP-A-10-297130 can be used.

  As a laser light source for irradiating the lithographic printing original plate of the present invention, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser or a semiconductor laser is preferable. The emission wavelength is preferably 760 to 850 nm. Examples of the light source for ultraviolet exposure include a carbon arc lamp, a mercury lamp, a metal halide lamp, a xenon lamp, and a chemical lamp. The emission wavelength is preferably 300 to 500 nm.

  As the developer and developer replenisher used for the development of the lithographic printing original plate of the present invention, an aqueous alkaline developer is suitable. Alkaline agents include sodium hydroxide, potassium, ammonium, lithium, sodium silicate, potassium, ammonium, lithium, tribasic sodium phosphate, potassium, ammonium, sodium borate, potassium, Inorganic alkaline agents such as ammonium and sodium carbonate, and organic alkalis such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, sodium octoate, and tetramethylammonium hydroxide Agents and the like. These alkali agents may be used alone or in combination of two or more.

  A surfactant, an organic solvent, a chelating agent, and the like can be added to the developer and the development replenisher as necessary. As the surfactant, an anionic surfactant or an amphoteric surfactant can be used.

  Examples of the anionic surfactant include sulfuric esters of alcohols having 8 to 22 carbon atoms (for example, polyoxyethylene alkyl sulfate soda salt), alkyl aryl sulfonates (for example, sodium dodecylbenzenesulfonate, polyoxyethylene dodecylphenyl). For example, sulfate soda salt, alkyl naphthalene sulfonate soda, naphthalene sulfonate soda, formalin condensate of naphthalene sulfonate soda, sodium dialkyl sulfonate, alkyl ether phosphate, alkyl phosphate, and the like can be used. In addition, as the amphoteric surfactant, for example, alkylbetaine type and alkylimidazoline type surfactants are preferable.

  As the solvent, alcohols and ethers are preferable, but solvents that do not dissolve 10% or more in water (20 ° C.) are preferable. Examples of this type of solvent include benzyl alcohol and phenyl glycol. . Furthermore, water-soluble sulfites such as sodium sulfite, potassium sulfite, lithium sulfite, and magnesium sulfite can be added.

Examples of the chelating agent include polyphosphoric acids such as Na ₂ P ₂ O ₇ , Na ₅ P ₃ O ₃ , Na ₃ P ₃ O ₇ , calgon (sodium polymetaphosphate), such as ethylenediaminetetraacetic acid, its potassium salt, and its sodium Salt, amine salt thereof, diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof, triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid, potassium salt thereof, sodium salt thereof, nitrilotriacetic acid, And organic phosphonic acids such as potassium salt, sodium salt, 1,2-diaminocyclohexanetetraacetic acid, potassium salt, sodium salt, aminotri (methylenephosphonic acid), potassium salt, sodium salt and the like. . Of these, ethylenediaminetetraacetic acid, its potassium salt, its sodium salt, its amine salt, ethylenediaminetetra (methylenephosphonic acid), its ammonium salt, its potassium salt, hexamethylenediaminetetra, its ammonium salt, and its potassium salt are preferred. The optimum amount of such a chelating agent varies depending on the hardness of the hard water used and the amount used, but is generally contained in the developer in the range of 0.01 to 5% by weight. Let

  The synthesis examples and examples of the present invention will be described in more detail below, but the present invention is not limited thereto.

Synthesis Example 1: Synthesis of copolymer solution 1 In a 500 ml four-necked round bottom flask equipped with a condenser, thermometer, and stirrer, 20 g of dicyclopentenyloxyethyl methacrylate, 40 g of vinyl cinnamate, 5 g of methacrylic acid, 2-hydroxy 15 g of ethyl methacrylate, 20 g of methyl acrylate and 100 g of cyclohexanone were added, and the mixture was heated and stirred at 80 to 85 ° C. in a nitrogen gas atmosphere. Further, 2,2′-azobis (2-methylbutyronitrile) was used as a polymerization initiator. Add 0.4 g and continue stirring for 6 hours. Thereafter, the reaction solution was cooled and then diluted with cyclohexanone to obtain a 30 wt% resin solution (copolymer solution 1). This resin had a polystyrene calculated weight average molecular weight of about 50,000 as determined by gel permeation chromatography (GPC).

Synthesis Example 2: Synthesis of copolymer solution 2 A copolymer solution 2 was synthesized in the same manner as in Example 1. The composition at this time was dicyclopentenyloxyethyl methacrylate / vinyl cinnamate / methacrylic acid / 2-hydroxyethyl methacrylate / methyl acrylate = 25/35/5/10/25% by weight. The polystyrene calculated weight average molecular weight was about 40,000 as determined by Eation Chromatography (GPC).

Synthesis Example 3: Synthesis of Comparative Copolymer Solution 3 For comparison, a copolymer solution 3 was synthesized in the same manner as in Example 1 as a copolymer excluding dicyclopentenyloxyethyl methacrylate. The composition at this time was vinyl cinnamate / methacrylic acid / 2-hydroxyethyl methacrylate / methyl acrylate = 50/5/20/25% by weight, and polystyrene by gel permeation chromatography (GPC) measurement of this resin. The calculated weight average molecular weight was about 40,000.

Preparation of Support After a 0.30 mm thick aluminum plate (material 1050) was degreased with alkali, the surface was polished with a nylon brush while applying a water suspension of Permiston, and then thoroughly washed with water. Next, a 15% by weight sodium hydroxide aqueous solution was poured for 5 seconds at 70 ° C., the surface was etched by 3 g / m ² , then further washed with water, and then an electrolytic solution composed of 1N hydrochloric acid and aluminum ions (20 g / L). Electrolytic polishing was performed at 200 coulomb / dm ² . Subsequently, after washing with water, the surface was etched again with a 15% by weight sodium hydroxide aqueous solution at 70 ° C., washed with water, and then anodized in a 15% sulfuric acid aqueous solution at 30 ° C. to obtain 2.0 g / m 2. ^Two anodized films were formed. After washing with water, it was immersed in a 5% by weight aqueous solution of potassium silicate A at 70 ° C. for 10 seconds, washed with water and dried.

Examples 1-3
Next, using the photosensitive solutions [A-1], [A-2], and [A-3] having the following compositions, they are applied on the aluminum plate and dried, and then Examples 1 to 3 are applied. Lithographic printing original plates [A-1], [A-2], and [A-3] were prepared. The coating amount at this time was 2.0 g / m ² in terms of dry mass.

Photosensitive solution [A-1]
Copolymer (A): Copolymer solution 1 (27.0 g)
Polymerizable compound (B): urethane acrylate (UA-61 manufactured by Shin-Nakamura Chemical Co., Ltd.)
00) (2.0 g)
Polymerization initiator (C): Triphenylphosphine (0.3 g)
2- (2,3-Dichlorophenyl) -4,5-dipheni
Ruimidazole dimer (0.3 g)
n-butyl-triphenylboron-tetrabutylan
Monium complex (1.0 g)
Infrared absorber (D): Cyanine compound (G) shown below (0.2 g)
Colorant ... Oil Blue 613 (0.3g)
Solvent ... Dioxolane (30 g)
Cyclohexanone (30g)

Photosensitive solution [A-2]
Copolymer (A) ... Copolymer solution 2 (27.0 g)
Polymerizable compound (B): ethoxylated isocyanuric acid triacrylate (Shin Nakamura)
Chemical industry NK ester A-9300) (2.0 g)
Polymerization initiator (C): Triphenylphosphine (0.3 g)
2- (2,3-dichlorophenyl) -4,5-diphe
Nilimidazole dimer (0.3 g)
n-butyl-triphenylboron-tetrabutyla
Numonium complex (1.0 g)
Infrared absorber (D): Cyanine compound (G) shown above (0.2 g)
Colorant ... Oil Blue 613 (0.3g)
Solvent ... Dioxolane (30 g)
Cyclohexanone (30g)

Photosensitive solution [A-3]
Copolymer (A): Copolymer solution 1 (27.0 g)
Polymerizable compound (B): ethoxylated isocyanuric acid triacrylate (Shin Nakamura)
Chemical industry NK ester A-9300) (2.0 g)
Polymerization initiator (C): Triphenylphosphine (0.3 g)
2- (2,3-Dichlorophenyl) -4,5-dipheni
Ruimidazole dimer (0.3 g)
n-butyl-tri (t-butylphenyl) boron-teto
Rabutylammonium complex (1.0 g)
Infrared absorber (D): Cyanine compound (G) shown above (0.2 g)
Colorant ... Oil Blue 613 (0.3g)
Solvent ... Dioxolane (30 g)
Cyclohexanone (30g)

[Comparative Example 1]
A lithographic printing original plate [B-1] according to Comparative Example 1 was produced using a comparative photosensitive solution [B-1] having the following composition, which was applied on the aluminum plate and dried. The coating amount at this time was 2.0 g / m ² in terms of dry mass.
Photosensitive solution for comparison [B-1]
Copolymer (A) ... Copolymer solution 3 (27.0 g)
Polymerizable compound (B): ethoxylated isocyanuric acid triacrylate (Shinnaka)
NK Ester A-9300 (Mura Chemical Industry Co., Ltd.) (2.0
g)
Polymerization initiator (C): Triphenylphosphine (0.3 g)
2- (2,3-dichlorophenyl) -4,5-diphe
Nilimidazole dimer (0.3 g)
n-butyl-triphenylboron-tetrabutyla
Numonium complex (1.0 g)
Infrared absorber (D): Cyanine compound (G) shown above (0.2 g)
Colorant ... Oil Blue 613 (0.3g)
Solvent ... Dioxolane (30 g)
Cyclohexanone (30g)

[Comparative Example 2]
A lithographic printing original plate [B-2] according to Comparative Example 2 was prepared using a comparative photosensitive solution [B-2] having the following composition, which was applied on the aluminum plate and dried. The coating amount at this time was 2.0 g / m ² by dry weight.
Polymer (A): Polymer (P-1) (8.0 g)
Polymerizable compound (B) ... above-mentioned compound (M-1) (2.0 g)
Polymerization initiator (C): Triphenylphosphine (0.3 g)
2- (2,3-dichlorophenyl) -4,5-diphe
Nilimidazole dimer (0.3 g)
n-butyl-triphenylboron-tetrabutyla
Numonium complex (1.6g)
Infrared absorber (D): Cyanine compound (G) shown above (0.2 g)
Colorant: 10% phthalocyanine pigment dispersion (1.5 g)
Solvent ... Dioxolane (30 g)
Cyclohexanone (30g)
The polymer (P-1) is a polymer synthesized by the method of Synthesis Example 1 of JP-A-2001-290271.

  The performance evaluation of each lithographic printing plate of Examples 1 to 3 and Comparative Examples 1 and 2 produced as described above was performed as follows.

[Evaluation of sensitivity]
Each of the above printing plates is exposed by using a semiconductor laser with a wavelength of 830 nm (manufactured by Creo: TrendSetter 400QTM) while changing the exposure amount in stages, and an automatic solution in which a diluent is charged to 1: 1 of the following composition developer Developed with a developing machine (Raptor 85 Thermal (manufactured by Glunz & Jensen)) at a liquid temperature of 30 ° C. with a development time of 12 seconds, 50% halftone reproduction is obtained, and it is necessary for the image to remain completely solid. The minimum exposure amount was evaluated as sensitivity. The results are shown in Table 1 below.

(Developer formulation)
40g triethanolamine
Sodium carbonate 4g
200 g of butyl naphthalene sulfonic acid
60g of phenyl glycol
Adjust to 1000 ml with water

[Evaluation of scratch resistance]
Each printing plate is exposed with the above-described semiconductor laser at the minimum exposure necessary for the image to remain completely solid, developed in the same manner as above, and rubbed with a sponge while washing the image portion with water, The degree of image loss and the ease of scratching were visually observed. The results are shown in Table 1 below. The evaluation criteria are as follows. ○: Scratches and missing images do not occur. (Triangle | delta): A crack | scratch generate | occur | produces in the sponge-like shape and the image omission of the part generate | occur | produces. X: All images are missing and do not become images.

[Evaluation of printing durability]
Using the semiconductor laser, each printing plate is irradiated with a solid portion and a halftone dot portion with a minimum exposure amount at which the solid portion is completely solid in each plate, and then developed in the same manner as described above, and then each printing plate Got. Next, each printing plate is set on a Heidelberg GTO printing machine, alkaline dampening water (LRH-ALKY (manufactured by Toyo Ink Co., Ltd.) 200-fold diluted solution) is used as dampening water, and lithographic printing ink (large Using Nihon Ink Chemical Co., Ltd. (F gloss ink), print on high-quality paper and count the number of printed sheets until 3% of the dots are missing. The results are shown in Table 1 below.

[Evaluation of banding (1)]
When exposed and developed with the above minimum exposure amount, streaking (banding) due to leakage light or focus laser light (light near 650 nm) for plate positioning is confirmed. The case where banding was clearly recognized was rated as x, and the case where no banding occurred was marked as ○. The results are shown in Table 1 below.

[Evaluation of banding (2)]
Stripes (banding) were confirmed when developed under the same development conditions as in the sensitivity evaluation except that the exposure was performed at an exposure amount 1.5 times the minimum exposure amount. The case where banding was clearly recognized was rated as x, and the case where no banding occurred was marked as ○. The results are shown in Table 1 below.

  As is apparent from Table 1, the lithographic printing plate precursor according to the present invention does not require an overcoat layer, provides a desired sensitivity at a low exposure amount, has excellent printing durability, and has excellent scratch resistance. It was found that the printing plate is excellent and suitable for infrared lasers, which does not generate streaks due to leakage light or focus laser light for positioning the plate.

Claims (4)

A copolymer having monomer units represented by the following formulas (I) and (II).

(In the formula, R ¹ represents a hydrogen atom or a cyano group, and m represents 0 or 1.)   A photosensitive composition comprising the copolymer according to claim 1.   The photosensitive composition of Claim 2 in which the said photosensitive composition further contains a polymeric compound, a polymerization initiator, and an infrared absorber. A photosensitive composition comprising an alkali-soluble copolymer having a monomer unit represented by formulas (I) and (II) according to claim 1, a polymerizable compound, a polymerization initiator, and an infrared absorber. A lithographic printing original plate in which an object is provided on a support.