JP2005275031A - Photosensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate having photosensitivity to infrared laser light of ≥750 nm, capable of forming excellent image quality, having good scuffing and blocking resistances, and requiring neither slip paper nor overcoat layer. <P>SOLUTION: In the photosensitive lithographic printing plate containing in a photosensitive layer of a polymer having an ethylenically unsaturated double bond in a side chain and having a carboxylic monomer as a copolymerized component, crosslinked polysiloxane particles having an average particle diameter of ≤1 μm are contained in the photosensitive layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photosensitive lithographic printing plate. More specifically, the present invention relates to a photosensitive lithographic printing plate for scanning exposure that is sensitive to light in the wavelength range of near infrared light to infrared light of 750 nm or more and forms an image. Regarding materials. In particular, the present invention relates to a photosensitive lithographic printing plate suitable for an automatic plate making system that does not require an interleaf or an overlayer.

  In recent years, in addition to conventional ultraviolet light (UV) as an exposure light source for photosensitive lithographic printing plates, visible to infrared laser light has been developed. Above all, solid lasers and semiconductor lasers that have a light emitting region from the near infrared to the infrared region are becoming more powerful and smaller, and a CTP (computer-to-plate) system that directly makes plates from digital data such as computers is promising. Development of scanning lithographic printing plates that are sensitive to infrared laser light has been actively conducted. From the viewpoint of work efficiency, the CTP system and the automatic plate making system for plate making work have been adopted. In such an automatic plate making system, several tens to thousands of plates are stacked on the plate feeding unit, and from there, exposure and plate making are sequentially performed. In this case, there are problems such as generation of scratches during transportation, loading, and plate making, and pressure bonding between the plate and the plate due to pressure (hereinafter blocking). For this problem, countermeasures such as sandwiching a sheet of paper (thin paper, film, laminated paper, etc.) between the plates or providing an over layer on the photosensitive layer are taken. However, when using an interleaf, problems such as troubles in the interleaf removal process before exposure and problems of increasing industrial waste occur. Various techniques such as JP-A-6-324478 (Patent Document 1) have been disclosed for providing an over layer on the photosensitive layer. However, a pre-water washing step for removing the over layer before development is disclosed. There is a problem that the presence of an over layer causes light scattering and the like during exposure to deteriorate image quality.

Further, as a countermeasure to be taken without providing an interleaf or over layer, there is a method disclosed in JP-A-57-34558 (Patent Document 2) in which a resin is dissolved or dispersed and sprayed on the surface of the photosensitive layer. There were problems such as missing matting agent. In addition, a technique disclosed in Japanese Patent Application Laid-Open No. 11-295882 (Patent Document 3) is disclosed in which a protrusion containing a monomer having a sulfonic acid as a constituent component is applied or dispersed on a photosensitive layer and heated to be dissolved and fixed. However, the matting agent used in the matting method that melts and fixes by heating is limited to the use of a matting agent that dissolves by heating to such an extent that the heating process does not adversely affect the photosensitive layer, and generally has a low hardness. Therefore, when pressure is applied, the matting agent is crushed or deformed to cause a blocking problem, or a matting agent that is large enough not to block even when crushed and deformed is required, and the influence on image quality and the like becomes a problem. As a technique for dispersing particles in the photosensitive layer and matting the surface, JP-A-11-109642 (Patent Document 4) discloses a technique for adding particles having rubber elasticity of 0.5 to 20 μm. However, due to the poor releasability, there were problems such as blocking when several hundred plates were stacked and aging, resulting in poor conveyance of the plates during plate making.
Japanese Patent Laid-Open No. 06-324478 JP-A-57-34558 JP 11-295882 A Japanese Patent Laid-Open No. 11-109642

  The present invention is a photosensitive lithographic printing plate having sensitivity to an infrared laser of 750 nm or more, forming excellent image quality, having good scratch resistance and blocking resistance, and does not require an interleaf or overlayer. It is an issue to provide.

  As a result of studies conducted by the inventors to solve this problem, (1) a polymer having an ethylenically unsaturated double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component in the photosensitive layer. A photosensitive lithographic printing plate containing a crosslinked polysiloxane particle having an average particle size of 1 μm or less in the photosensitive layer. (2) The photosensitive lithographic printing plate material described above, wherein the photosensitive layer contains a dye having absorption in a wavelength region of 750 nm or more and an organic borate. (3) The above photosensitive lithographic printing plate having no overlayer. This was achieved by the above (1), (2) and (3).

  A photosensitive lithographic printing plate having photosensitivity to an infrared laser of 750 nm or more, excellent image quality, good scratch resistance and blocking resistance, and no need for an interleaf or overlayer is obtained.

The present invention will be described in detail below.
The photosensitive layer of the photosensitive lithographic printing plate of the present invention contains crosslinked polysiloxane particles having an average particle size of 1 μm or less as a matting agent. The crosslinked polysiloxane particles used in the present invention are compounds having a siloxane skeleton having a repeating unit of the following chemical formula 1. Specific examples of the crosslinked polysiloxane particles having an average particle diameter of 1 μm or less used in the present invention include Tospearl manufactured by Toshiba Silicone Co., Ltd. The average particle size of the matting agent is a value measured by a centrifugal sedimentation method. The addition amount of the matting agent is preferably 0.5% by mass to 30% by mass with respect to the dry photosensitive layer. More preferably, it is the range of 2 mass%-25 mass%.

  R in Chemical Formula 1 is an alkyl group or an aryl group, and n is an integer of 1000 or more.

  The action mechanism of the present invention is estimated as follows. Filling with a matting agent having a fine particle size of 1 μm or less has no effect on image quality and can exert an effect on scratch resistance. In addition, for blocking prevention, the surface of the photosensitive layer itself is not pressure-bonded by utilizing the releasability and non-adhesiveness of the matting agent material of the crosslinked polysiloxane material, not the effect of adding a matting agent which has been conventionally performed. It is considered that a sufficient effect can be obtained because blocking can be prevented.

  The polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component used in the present invention will be described. As the carboxyl 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 monoalkyl ester, Examples include 4-carboxystyrene and the like.

  As monomers for introducing a polymerizable double bond into the polymer side chain, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl-acrylate, 1-propenyl-methacrylate, β-phenyl-vinyl- Methacrylate, β-phenyl-vinyl-acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro-vinyl-methacrylate, α-chloro-vinyl-acrylate, β-methoxy-vinyl-methacrylate, β-methoxy-vinyl-acrylate, vinyl -Thio-acrylate, vinyl-thio-methacrylate and the like.

  The polymer used in the present invention is particularly preferably a polymer having a phenyl group substituted with a vinyl group in a side chain and a carboxy group-containing monomer as a copolymerization component. The phenyl group substituted with a vinyl group is bonded to the main chain directly or through a linking group, and the linking group is not particularly limited, and includes any group, atom, or a combination thereof. The phenyl group may be substituted with a substitutable group or atom, and the vinyl group is a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, It may be substituted with an aryl group, an alkoxy group, an aryloxy group or the like. More specifically, the polymer having a phenyl group in which a vinyl group is substituted on the side chain described above has a group represented by the following chemical formula 2 in the side chain.

In the formula, Z ₁ represents a linking group, and R ₁ , R ₂ , and R ₃ 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. A 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 ₄ 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 ₅ ) —, —C (O) —O—, —C (R ₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following chemical formula 3 alone or in combination of two or more. Here, R ₅ and R ₆ 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.
Although the example of group represented by Chemical formula 2 is shown below, it is not limited to these examples.

Among the groups represented by the above chemical formula 2, there are preferable groups. That is, it is preferable that R ₁ and R ₂ are hydrogen atoms and R ₃ 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.

  Examples of polymers having a group represented by Chemical Formula 2 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%.

  The 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 or alkylaryl esters such as phenyl methacrylate and benzyl methacrylate , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester methacrylate, methoxyethylene methacrylate Methacrylic acid esters having an alkyleneoxy group such as glycol monoester and methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid esters such as 2-dimethylaminoethyl methacrylate and 2-diethylaminoethyl methacrylate, or acrylic acid esters Examples of these corresponding methacrylic acid esters, or monomers having a phosphoric acid group such as vinylphosphonic acid, amino group-containing monomers such as allylamine and diallylamine, or vinylsulfonic acid and its salts, allylsulfone Monomers having a sulfonic acid group such as acid and its salt, methallylsulfonic acid and its salt, styrenesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfonic acid and its salt As monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or monomers having a quaternary ammonium base, 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyl Trimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, or acrylonitrile, methacrylonitrile, Acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropyl acrylate Acrylamide or methacrylamide derivatives such as amide, 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, and vinyl ethers such as methyl vinyl ether and butyl vinyl ether, N-vinyl pyrrolidone, acryloyl morpholine, tetrahydrofurfuryl methacrylate, vinyl chloride , Various monomers such as vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, glycidyl methacrylate, etc. And the like.

  There is a preferred range for the molecular weight of the 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.

The sensitizing dye used in the present invention sensitizes the decomposition of the photopolymerization initiator with light in the near-infrared to infrared wavelength region of 750 nm or more. Merocyanine, coumarin, xanthene, thioxanthene, azo dye and the like can be used as the dye and neutral dye having no charge. 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.
Examples of particularly preferred sensitizing dyes are shown below.

  There is a preferred range for the proportion of the sensitizing dye in the photosensitive composition, and the sensitizing dye is contained in the range of 0.01 to 50 parts by mass in 100 parts by mass of the photosensitive composition. It is preferable.

  As the photopolymerization initiator of the present invention, any compound can be used as long as it is a compound capable of generating radicals by light irradiation. For example, trihaloalkyl-substituted compounds (for example, triazine compounds and oxadiazole derivatives as trihaloalkyl-substituted nitrogen-containing heterocyclic compounds, trihaloalkylsulfonyl compounds), hexaarylbisimidazoles, titanocene compounds, ketoxime compounds, thio compounds, organic compounds A peroxide etc. are mentioned. Among these photopolymerization initiators, organic boron salts are preferably used, and more preferably, organic boron salts and trihaloalkyl-substituted compounds are used. As the organic boron salt preferably used, a compound having an organic boron anion represented by Chemical formula 15 is used.

In the chemical formula 15, R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ may be the same or different, and may be an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. Represents. 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.

  As said organic boron salt, it is a salt containing the organic boron anion represented by Chemical formula 15 shown previously, and an alkali metal ion and an onium compound are preferably used as a cation which forms a salt. Particularly preferable examples of the onium salt with an organic boron anion include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

  There is a preferable range for the proportion of the organic boron salt in the photosensitive composition, and the organic boron salt is contained in the range of 0.1 to 50 parts by mass in 100 parts by mass of the photosensitive composition. Preferably it is.

  A preferable photopolymerization initiator used in combination with the organic boron salt according to the present invention is a trihaloalkyl-substituted compound. The trihaloalkyl-substituted compound mentioned here is specifically a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule, and preferred examples include the trihaloalkyl group. Examples of the compound bonded to the nitrogen heterocyclic group include s-triazine derivatives and oxadiazole derivatives, or a trihaloalkylsulfonyl compound in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocyclic ring via a sulfonyl group. Can be mentioned.

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

  When a trihaloalkyl-substituted compound is used, there is a preferred range in the photosensitive layer of the photosensitive lithographic printing plate, and the proportion in the total 100 parts by mass of the photosensitive layer is 0.1 to 50 parts by mass. It is preferably included in the range of parts. Further, these are preferable because the sensitivity is particularly improved when they are contained in the photosensitive layer together with the above-described organic boron salt. In this case, the ratio to the organic boron salt is trihaloalkyl substitution with respect to 1 part by mass of the organic boron salt. The compound is preferably contained in the range of 0.1 to 50 parts by mass.

  The photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably contains a colorant. It is used for enhancing the visibility of the image area, and more preferably has absorption in the visible light region in order to improve the safelight property. Examples of these colorants include inorganic pigments, organic pigments, and dyes as described below.

  Examples of inorganic pigments include mica-like iron oxide, red lead, yellow lead, silver vermilion, ultramarine, titanium dioxide, coated mica, stone team chromate, titanium yellow, zinc chromate, molybdenum red, chromium oxide, calcium leadate, and the like. . Organic pigments include carbon black, phthalocyanine pigment, monoazo pigment, disazo pigment, condensed azo pigment, isoindolinone pigment, quinophthalone pigment, nickel azo pigment, perinone pigment, perylene pigment, anthrone pigment, quinacridone pigment, anthraquinone pigment, Examples thereof include thioindigo pigments, dioxazine pigments, indanthrone pigments, and pyranthrone pigments. Examples of the dye include various dyes such as a phthalocyanine dye, a triarylmethane dye, an anthraquinone dye, and an azo dye.

  The above pigments and dyes may be used alone, but two or more of them may be used in combination.

  The pigment is preferably added to the photosensitive layer of the lithographic printing plate in a state dispersed in an organic solvent by a disperser such as a paint conditioner, a ball mill, a jet mill, or a homogenizer, and the dye is added in a state dissolved in the organic solvent. It is preferable.

  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 in the molecule. Examples of preferred ethylenically unsaturated compounds include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene Polyfunctional acrylic monomers such as glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate and the like can be mentioned.

  Alternatively, an oligomer having radical polymerizability is preferably used in place of the above-described polymerizable compound, and polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, etc. as various oligomers into which acryloyl group or methacryloyl group is introduced Are also used in the same manner, but these can also be preferably used as ethylenically unsaturated compounds.

  A more preferred embodiment of the ethylenically unsaturated compound is 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, so that it is extremely preferable for producing a highly sensitive 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 ₂ 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. m ₂ represents an integer of 0 to 4, and k ₂ represents an integer of 2 or more.

Further details will be described. As the linking group for Z ₂ , 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, or a group in which two or more are combined. 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.

Among the compounds represented by the above formula 20, there are preferable compounds. That is, R ₁₁ and R ₁₂ are hydrogen atoms, R ₁₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₂ is preferably a compound having 2-10. Specific examples of the compound represented by Chemical Formula 20 are shown below, but are not limited to these examples.

  There is a preferred range for the proportion of the ethylenically unsaturated compound as described above in the photosensitive layer of the photosensitive lithographic printing plate, and the ethylenically unsaturated compound is from 1 part by mass to 60 parts in a total of 100 parts by mass of the photosensitive layer. It is preferably contained in the range of 5 parts by mass, more preferably in the range of 5 to 50 parts by mass.

  A polymerization inhibitor can also be preferably added as another element constituting the photosensitive lithographic printing plate. For example, compounds such as quinone and phenol are preferably used, and compounds such as hydroquinone, p-methoxyphenol, catechol, t-butylcatechol, 2-naphthol, and 2,6-di-t-butyl-p-cresol are used. Preferably used. The preferred proportion of these polymerization inhibitors and the aforementioned ethylenically unsaturated compounds is preferably used in the range of 0.001 to 0.1 parts by mass with respect to parts by mass of the ethylenically unsaturated compounds.

  Regarding the thickness of the photosensitive layer itself of the photosensitive lithographic printing plate, 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. It is extremely preferable to improve it. The photosensitive layer is coated and dried on the support 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.

  Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, hopper coating, blade coating, and wire doctor coating.

  As the developer of the present invention, any aqueous alkaline solution can be used as long as the pH is 8 or more. Examples of the alkali agent include sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, sodium borate, potassium borate, ammonium borate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, Inorganic alkaline agents such as potassium carbonate, ammonium carbonate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, trisodium phosphate, tribasic potassium phosphate and tribasic ammonium phosphate, monomethylamine , Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine , Monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-ethylethanolimine, Nn-butylethanolamine, Nt-butylethanolamine, Nn-butyldiethanolamine, Nt-butyldiethanolamine N-methylethanolamine, N-methyldiethanolamine, N-aminoethylethanolamine, N-aminoethylpropanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Examples include organic alkali agents, alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate, and ammonium silicate. These can be used alone or in combination of two or more.

  The developer used in the present invention can be used in combination with other various surfactants, and examples thereof include anionic, cationic, nonionic and amphoteric surfactants. These surfactants used in combination are added to the developer in the range of 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

  Various development stabilizers can be used in the developer used in the present invention. Preferred examples thereof include polyethylene glycol adducts of sugar alcohols described in JP-A-6-282079, phosphonium salts such as tetrabutylphosphonium bromide, and iodonium salts such as diphenyliodonium chloride. Furthermore, anionic surfactants or amphoteric surfactants described in JP-A-50-51324, water-soluble cationic polymers described in JP-A-55-95946, and JP-A-56-142528 are described. There are water-soluble amphoteric polyelectrolytes that have been described. Further, an organic boron compound to which an alkylene glycol is added as described in JP-A No. 59-84241, a polyethylene glycol having a weight average molecular weight of 300 or more as described in JP-A No. 61-215554, and a cation as described in JP-A No. 63-175858. And a fluorine-containing surfactant having a functional group, a water-soluble ethylene oxide adduct obtained by adding 4 mol or more of an acid or an alcohol or an alcohol disclosed in JP-A-2-39157, and a water-soluble polyalkylene compound.

  It is advantageous in terms of transportation that the developer used in the present invention is a concentrated solution in which the water content is less than that in use, and is diluted with water at the time of use. The degree of concentration in this case is suitably such that each component does not cause separation or precipitation, and depending on the content, it can usually be concentrated to about concentrate: water = 1: 0 to 1:10. In addition, since the container is alkaline, it is preferable to use a material that does not permeate carbon dioxide and that does not break during transportation for safety. Usually, a resin container such as a hard bottle or a cubicener is preferably used.

  In the processing method of the present invention, the processing is performed with a normal automatic processor after exposure. The automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray tank, and is assembled by a pump while horizontally transporting the exposed printing plate. Each processing solution is sprayed from a spray nozzle to develop and post-process. Recently, a developing method has been developed in which a printing plate is dipped and conveyed by a submerged guide roll in a developing tank filled with a developing solution, and such a developing method can also be suitably applied to the present invention. . Such an automatic developer can be processed while replenishing the replenisher according to the development processing amount, operating time, and the like.

  The printing plate developed with the developer having such a composition is subjected to post-processing with a washing water, a rinse solution containing a surfactant, a finisher mainly composed of gum arabic or starch derivatives, or a protective gum solution. The In the post-treatment of the printing plate of the present invention, these treatments can be used in various combinations. For example, development → water washing → rinsing liquid treatment containing surfactant or development → water washing → finisher liquid treatment is a rinse liquid or finisher. Less liquid fatigue is preferable. Furthermore, a countercurrent multistage process using a rinse liquid or a finisher liquid is also a preferred embodiment. These post-processing are generally performed using an automatic developing machine including a developing unit and a post-processing unit. As the post-treatment liquid, a method of spraying from a spray nozzle or a method of conveying through a treatment tank filled with the treatment liquid is used. A method is also known in which a small amount of aqueous water is supplied to the plate surface after development and washed with water, and the waste solution is reused as dilution water for the developer stock solution. In such automatic processing, each processing solution can be processed while being replenished with the respective replenishing solution according to the processing amount and operating time. In addition, a so-called disposable treatment method in which treatment is performed with a substantially unused post-treatment liquid can be applied. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing.

  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. The part in an Example shows a mass part.

  According to the method described in JP-A-2000-290271 as a polymer synthesis example, a monomer obtained by reacting equimolar amounts of chloromethylstyrene and bismuthiol and methacrylic acid are neutralized with triethylamine and polymerized in ethanol. After completion, Chemical Formula 8 (P-1) synthesized by adding chloromethylstyrene was used. As the matting agent, Tospearl 105 (average particle size 0.5 μm) and Tospearl 240 (average particle size 4.0 μm) are both manufactured by Toshiba Silicone Corporation (crosslinked polysiloxane matting agent), Chemisnow MP-5000 (average particle size) 0.4 μm acrylic / styrene copolymer matting agent), and after preparing a photosensitive composition liquid according to the following formulation, on an aluminum plate subjected to graining treatment and anodizing treatment with a thickness of 0.30 mm with a wire doctor coater The sample was coated so that the dry film thickness was 5 μm and dried with hot air at 90 ° C. to prepare a sample coated with the photosensitive composition. Sample contents are shown in Table 1.

<Coating liquid for photosensitive composition>
Polymer 8 (P-1) 10% dioxane solution
300 parts by weight Matting agent Table 1 type and amount (parts by weight)
Photopolymerization initiator
17 (BC-5) 4 parts by mass
19 (BS-1) 2 parts by mass Ethylenically unsaturated compound
Chemical formula 21 (C-5) 15 parts by mass Pentaerythritol tetraacrylate 10 parts by mass Sensitizing dye Chemical formula 13 (S-33) 0.4 part by mass Polymerization inhibitor 2,6-di-t-butylcresol
0.2 parts by mass Solvent 1,3-dioxolane 70 parts by mass
20 parts by mass of cyclohexanone Carbon black with an average particle size of 185 nm
15% by weight of 25% methyl ethyl ketone solution

The sample prepared as described above was cut into 5 cm ² squares, the burrs on the end face were removed, the layers were stacked so that the photosensitive layer surface and the back surface of the support were in contact, and a weight of 15 kg / cm ² was applied to the photosensitive layer surface while the temperature was 35 The sample was allowed to stand for 1 month in a heater with a temperature of 80% and a humidity of 80%.

○: No blocking ×: Blocking (Some parts of the photosensitive layer stick to the back side, or two sheets are lifted simultaneously)

  For samples 1 to 7 prepared in the same manner, a HEIDON-18 type continuous load type scratch tester was used, a needle tip of 500 μm was attached, and the contact angle between the needle tip and the photosensitive layer of the sample was 60 °. The method of entering a wound when scratching with a weight of 50 g was evaluated according to the following evaluation criteria. (Scratch test 1) Table 2 shows the results.

○: No scratches.
○ △: A mark remains but does not become a scratch.
X: Scratches occur.

  Samples 1 to 7 produced in the same manner were cut into 398 mm × 1100 mm, and each 40 sheets were stacked so that the photosensitive layer surface and the back surface of the support were in contact with each other. This was packaged with paper, packaged with a cardboard case, packaged, and subjected to a truck transportation test. The scratches were evaluated according to the following evaluation criteria. (Scratch test 2). The results are shown in Table 2.

○: No scratches.
X: Scratches occur.

A sample prepared in the same manner as above, using an external drum plate setter mounted with a 830 nm semiconductor laser, PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd., drum rotation speed 1000 rpm resolution 2400 dpi, laser irradiation energy 100 mJ / cm ² And 50% flat screen exposure. After exposure, an automatic developing machine PD-1310 manufactured by Dainippon Screen Mfg. Co., Ltd. was used as an automatic developing machine, and the following developing solution was used to carry out a developing process at a liquid temperature of 29 ° C. for 15 seconds, followed by A gum solution having the following formulation was applied.

<Developer>
35% sodium alkylnaphthalene sulfonate
(Surfactant manufactured by Kao Corporation) 30g
KOH 25g
50 g of 20% potassium silicate aqueous solution (containing 20% SiO ₂ ) 50 g
N-aminoethylethanolamine 30g
1L with water
<Gum solution>
1g potassium phosphate 5g
Gum arabic 25g
Dehydroacetic acid 0.5g
EDTA2Na 1g
1L with water

  For the lithographic printing plate prepared as described above, the sharpness of the edge portion of the halftone dots was observed, the image quality was evaluated according to the following evaluation criteria, and the results are shown in Table 2.

○: A uniform halftone image is formed with sharp edges.
X: Unevenness is seen in the edge portion of the image and a non-uniform network image is formed.

  Sample No. Although the image part and the non-image part were formed for the sample of evaluation judgment ○ Δ of the scratch test 1 of No. 1, no adverse effect was observed. For the sample of evaluation evaluation x in the scratch test 1 of No. 7, scratches appeared in the image area, and elution defects occurred in the non-image area.

  From the above results, it can be seen that the present invention sufficiently retains scratch resistance and blocking resistance without deteriorating excellent image quality and without requiring a slip sheet or an over layer.

Claims (3)

  In a photosensitive lithographic printing plate containing a polymer having an ethylenically unsaturated double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component in the photosensitive layer, the photosensitive layer has an average particle size of 1 μm or less. A photosensitive lithographic printing plate comprising cross-linked polysiloxane particles.   2. The photosensitive lithographic printing plate material according to claim 1, wherein the photosensitive layer contains a dye having an absorption in a wavelength region of 750 nm or more and an organic borate.   The photosensitive lithographic printing plate according to claim 1, which does not have an overlayer.