JP2005275032A - Photosensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate material which stably prevents banding by multichannel infrared laser scanning exposure and dose not cause stain by banding. <P>SOLUTION: In a photosensitive lithographic printing plate obtained by applying on a support a photosensitive layer containing an alkali-soluble polymer, a photopolymerization initiator and a sensitizing dye having absorption at 750-900 nm and capable of sensitizing the photopolymerization initiator and by further applying an overcoat layer on the photosensitive layer, at least a dye having absorption at 750-900 nm is contained in the overcoat layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photosensitive lithographic printing plate capable of forming an image using a scanning exposure apparatus, and more particularly to a photosensitive lithographic printing plate for infrared laser scanning exposure.

  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. Among them, 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. Among these, it has a photopolymerization initiator, a dye sensitizer and a polymerizable compound, and utilizes polymerization of a polymerizable compound by radicals that generate light energy absorbed by the dye sensitizer from the photopolymerization initiator. JP-A-2001-290271 (Patent Document 1) discloses a photosensitive composition containing a polymer having a phenyl group substituted with a vinyl group in the side chain, a photo radical generator, and a sensitizing dye.

  On the other hand, problems common to direct-drawing photopolymerization systems using various laser beams include high sensitivity and banding. Banding means that when scanning exposure is performed with laser light, weak laser light is emitted, so when recording with laser light from multiple channels, it is synchronized with the scanning pitch due to slight overlap of multi-channel lasers. A phenomenon in which recording unevenness occurs, affects not only the image portion but also the non-image portion, and causes the non-image portion to become dirty and the network image to be clogged. In order to improve the recording speed using laser light, it is necessary to increase the sensitivity of the photoconductor, but on the other hand, such banding problems are inevitably generated.

To deal with such banding problems, Japanese Patent Application Laid-Open No. 2000-3031 (Patent Document 2) discloses a technique using ketones or glycol ethers as a solvent for a photosensitive composition. This was not sufficient as a stable measure depending on the storage state of the lithographic printing plate. Japanese Patent Application Laid-Open No. 2002-214776 (Patent Document 3) describes a technique in which a dye having the same wavelength as that of the photosensitive region is further added to the photosensitive layer as a banding inhibitor. This is not a sufficient measure because the balance between the dye as the banding inhibitor and the sensitizing dye is lost due to the storage state of the material, and a stable banding suppression effect cannot be obtained.
JP 2001-290271 A JP 2000-3031 A Japanese Patent Application Laid-Open No. 2002-214776

  An object of the present invention is to provide a photosensitive lithographic printing plate that stably prevents banding due to multi-channel infrared laser scanning exposure and does not generate stains due to banding.

  (1) On a support, a photosensitive layer containing an alkali-soluble polymer, a photopolymerization initiator, a sensitizing dye having absorption at 750 nm to 900 nm capable of sensitizing the photopolymerization initiator, and on the photosensitive layer A photosensitive lithographic printing plate comprising an over layer sequentially coated, wherein the over layer contains a dye having absorption at least from 750 nm to 900 nm. (2) The alkali-soluble polymer is a polymer having an ethylenically unsaturated double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component, and the photopolymerization initiator is an organic boron salt. The photosensitive lithographic printing plate as described above. Basically achieved by (1) and (2).

  The present invention provides a photosensitive lithographic printing plate that stably prevents banding due to multi-channel infrared laser scanning exposure and does not cause contamination due to banding.

  The photosensitive lithographic printing plate of the present invention is characterized in that an over layer containing a dye having absorption at least from 750 nm to 900 nm is laminated on the photosensitive layer. The over layer used in the present invention is preferably made of a hydrophilic polymer that is soluble in water or a mixed solvent with a water-miscible organic solvent, rather than being laminated on the photosensitive layer. Specific examples of the hydrophilic polymer include polyvinyl alcohol, polyvinyl alcohol partially substituted with ester, ether, acetal, cellulose such as polyvinyl pyrrolidone, polyethylene noxite, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc. Gelatin, gum arabic, methyl vinyl ether-maleic anhydride copolymer, partially saponified polyacrylate ester, natural polysaccharide, and the like. More preferably, gelatin, gum arabic, polyvinyl alcohol, polyvinyl alcohol partially substituted with ester, ether, acetal, polyvinyl pyrrolidone than the coating step at the time of photosensitive lithographic printing plate preparation and the development step at the time of plate making. good.

The coating amount of the overlayer used in the present invention is preferably in the range of 0.1 g / m ² to 10 g / m ² , more preferably 0.1 g / m ² to 6 g / m after drying. ² .

  The overlayer used in the present invention is coated and dried using various known coating methods. Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, spray coating, slide bead coating, hopper coating, blade coating, and wire doctor coating.

Any dye having absorption at 750 nm to 900 nm used in the overlayer of the present invention can be used as long as it is a dye having absorption at least from 750 nm to 900 nm. In order to act effectively and accurately, it is preferable to contain a dye having an absorption maximum from 750 nm to 900 nm. As these dyes, various cationic dyes, anionic dyes, neutral dyes having no charge, merocyanine, coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Preferred examples include a dye selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dye as a cationic dye, It can be used alone or in combination of two or more. As the addition amount, it is necessary to add an amount appropriately adjusted according to the sensitivity of the photosensitive layer, the film thickness of the over layer, etc., but as an approximate preferable addition amount, when one is used alone, two or more are used together. the addition amount of the total, it is preferably added in the range of ^{0.0001g / m 2 ~0.1g / m 2} . The content can be dispersed or dissolved in the overlayer and added, but it is preferably dissolved and added. When the hydrophilic polymer is used as the overlayer, it is more preferable to use a water-soluble dye. Examples of further preferable water-soluble dyes are shown below, but are not limited to these examples.

  The action mechanism of the present invention is presumed as follows. Although the cause of the weak laser light leaking, which is the cause of banding, is not clear, the part that is not originally irradiated with laser light is irradiated with laser light that is considerably weaker than normal exposure. The sensitizing dye in the photosensitive layer absorbs the leaked light and acts on the photopolymerization initiator to start the polymerization, and banding occurs. In particular, a slight overlap portion of the multi-channel laser is irradiated with leakage light twice, so that recording unevenness synchronized with the scanning pitch occurs. When this is dealt with by adjusting to reduce the sensitivity of the photosensitive layer, the strength of the image area is lowered and the printing durability is affected. In the photosensitive layer, it is necessary to form a good image with an exposure energy obtained by subtracting all or one part of the leakage light energy from the normal exposure energy. There is a large difference between the energy for normal exposure and the exposure energy for leakage light, and there is a large difference in the amount of radicals generated by each energy. Polymerization of radicals is probabilistically strongly correlated with radical density, and because one radical is generated, one polymerization does not occur, but polymerization is caused by the presence of radicals of a certain density or higher. Therefore, it is possible to take a countermeasure with substantially no problem by absorbing an appropriate amount of leaked light. The overlayer containing a dye having absorption at 750 nm to 900 nm of the present invention can absorb this weak light leakage before the sensitizing dye in the photosensitive layer absorbs, thereby preventing banding. Therefore, a banding prevention over layer is required on the photosensitive layer. By absorbing the leaked light in the over layer separated from the photosensitive layer, an efficient, stable and reliable effect can be exhibited. Of course, the effect of the original photosensitive layer on image formation must be taken into account, but it is necessary to add a dye that absorbs excessive leakage light by being able to absorb the leakage light stably and reliably. However, the addition of the necessary minimum amount is sufficient, the influence of the original photosensitive layer on image formation can be minimized, and there is substantially no problem.

  In the over layer of the present invention, in addition to the binder polymer and the dye having absorption at 750 nm to 900 nm, for example, nonionic, anionic, cationic, betaine, fluorine-based surfactants, antifoaming agents, It is also one of preferable modes to contain inorganic particles and organic particles as a plasticizer and a matting agent, a dye that does not absorb light in the photosensitive region, a pigment, and an antioxidant. Further, an over layer having other functions such as scratch resistance, storage stability with time, and blocking resistance may be provided on the over layer of the present invention.

  As the alkali-soluble polymer used in the present invention, any polymer can be used as long as it is soluble in an alkali having a pH of 8 or higher. A polymer having ethylenic unsaturation capable of addition polymerization is preferred, and a polymer having a polymerizable double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component is more preferred.

  Regarding the polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component preferably used in the present invention, examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, acrylic acid 2- Examples include carboxyethyl ester, methacrylic acid 2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 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 -Ethio-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 4 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 5 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 4 is shown below, it is not limited to these examples.

Among the groups represented by the above chemical formula 4, there are preferable ones. 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 4 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 photosensitive layer of the present invention sensitizes the decomposition of the photopolymerization initiator in the light of the near infrared to infrared wavelength region of 750 to 900 nm. For example, merocyanine, coumarin, xanthene, thioxanthene, and azo dyes can be used as neutral dyes, anionic dyes, and neutral dyes 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 and trihaloalkyl-substituted compounds are preferably used. More preferably, an organic boron salt and a trihaloalkyl-substituted compound are used in combination.

  As the organic boron salt preferably used in the present invention, a compound having an organic boron anion represented by Chemical formula 17 is preferably used.

In the chemical formula 17, 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, 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 17 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 preferred photopolymerization initiator used in combination with the organic boron salt used in 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. These pigments or dyes may be used singly or in combination of two or more.

  The pigment is preferably added to the photosensitive layer of the photosensitive 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 dissolved in the organic solvent. It is preferable to add.

  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 photosensitive 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 22, there are preferred 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 22 are shown below, but the invention is 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, slide bead 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 photosensitive lithographic printing plate obtained by such treatment is placed 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, a photosensitive coating solution having the following formulation of photosensitive solution was prepared using Chemical Formula 10 (P-1) synthesized by adding chloromethylstyrene, and then grained with a wire doctor coater having a thickness of 0.30 mm. The sample was coated on the aluminum plate that had been subjected to the treatment and anodizing treatment so that the dry film thickness was 4 microns, and was dried with hot air at 90 ° C. to prepare a sample coated with the photosensitive layer. On top of that, an over liquid is prepared by the following formulation of over liquid 1 and over liquid 2, and is coated with a wire doctor coater so that the mass after drying is 1 g / m ² and dried with hot air at 55 ° C. The photosensitive lithographic printing plates of Samples 1 to 7 were obtained. Also, two types of over liquids, the following prescription over liquid 3-a and over liquid 3-b, were prepared, and the over liquid 3-a was dried on the photosensitive layer of the sample coated with the photosensitive layer with a dry mass of 1 g / m ^2. On top of that, two layers were simultaneously applied by a slide bead coating application method so that the over liquid 3-b had a dry mass of 2 g / m ^2, and dried with hot air at 60 ° C. to prepare Sample 8. Sample contents are listed in Table 1.

<Photosensitive solution>
Polymer 10 (P-1) 10% dioxane solution 300 parts by weight Photopolymerization initiator Chemical 19 (BC-5) 4 parts by weight Chemical 21 (BS-1) 2 parts by weight Ethylenically unsaturated compound Chemical 23 (C-5) ) 15 parts by mass Pentaerythritol tetraacrylate 7 parts by mass Sensitizing dye Chemical formula 15 (S-33) 0.3 part by mass Polymerization inhibitor 2,6-di-t-butylcresol 0.2 part by mass Solvent 1,3-dioxolane 70 parts by mass cyclohexanone 20 parts by mass Carbon black with an average particle size of 185 nm
5% by weight of 25% methyl ethyl ketone solution

<Over liquid 1>
Polymer Polyvinyl alcohol (GL-05R manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 5 parts by mass Polyvinylpyrrolidone (K-30 manufactured by Tokyo Chemical Industry Co., Ltd.) 5 parts by mass Dye Types listed in Table 1 0.03 parts by mass Interface Activating agent Anionic surfactant (Nikko Chemical Co., Ltd. OTP-75) 0.2 parts by weight Solvent distilled water 90 parts by weight <over liquid 2>
Polymer Polyvinyl alcohol (GL-05R manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 5 parts by mass Polyvinylpyrrolidone (K-30 manufactured by Tokyo Chemical Industry Co., Ltd.) 5 parts by mass Dye Types listed in Table 1 0.03 parts by mass Matte Agent Cross-linked acrylic particles (MX-180 manufactured by Soken Chemical Industry Co., Ltd.) 0.5 parts by mass Surfactant Anionic surfactant (OTP-75 manufactured by Nikko Chemical Co., Ltd.) 0.2 parts by mass Solvent distilled water 90 Part by mass <Over liquid 3-a>
Polymer Polyvinyl alcohol (GL-05R manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 5 parts by mass Polyvinylpyrrolidone (K-30 manufactured by Tokyo Chemical Industry Co., Ltd.) 5 parts by mass Dye Types listed in Table 1 0.03 parts by mass Interface Activating agent Anionic surfactant (Nikko Chemical Co., Ltd. OTP-75) 0.2 parts by mass Solvent distilled water 190 parts by mass <over liquid 3-b>
Polymer Polyvinyl alcohol (GL-05R manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 5 parts by mass Polyvinylpyrrolidone (K-30 manufactured by Tokyo Chemical Industry Co., Ltd.) 5 parts by mass Matting agent Cross-linked acrylic particles (Soken Chemical Industry Co., Ltd.) 0.3-part by weight surfactant Anionic surfactant (OTP-75 by Nikko Chemical Co., Ltd.) 0.3 part by weight Betaine surfactant (AM-manufactured by Nippon Surfactant Co., Ltd.) 2150)
0.1 parts by mass Solvent distilled water 190 parts by mass

  Using a Trendsetter 800II Quantum manufactured by Creo (a multi-channel scanning exposure apparatus using a light source 830 nm laser), the printing image containing 50% halftone dots is exposed with a light amount of 7 W. After exposure, Dainippon Screen Mfg. Co., Ltd. PS plate automatic processor PD-1310 was used as an automatic processor, and the following developer was used for processing at a liquid temperature of 28 ° C. for 20 seconds. A gum solution 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

  The lithographic printing plate prepared as described above was subjected to banding evaluation, image quality evaluation and printing evaluation according to the following evaluation criteria. As the image quality evaluation, 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. As printing evaluation, printing durability and stain resistance were evaluated. Evaluation of printing durability was performed using Heidelberg TOK (trademark of an offset printing machine manufactured by Haidelberg) as a printing machine, with a 0.1 mm gauge film sandwiched between the plate cylinder and the plate, and the pressure during printing being increased. Use 1% aqueous solution of BEST ONE Ink H (T & KTOKA Co., Ltd.) and Astro Mark III (Niken Chemicals Co., Ltd.) as the dampening solution. The evaluation was based on the number of sheets that were missing and could not be printed. In addition, as an evaluation of stain resistance, the printing press uses Heidelberg TOK (trademark of an offset printing press manufactured by Haidelberg), and a pressure gauge during printing is increased by sandwiching a gauge film of 0.05 between the plate cylinder and the plate. The ink is FINE INK New Champion Purple S (Dainippon Ink Chemical Co., Ltd.), and the dampening solution is Eu-3 (Fuji Photo Film Co., Ltd. PS plate dampening solution). Using a 0.5% aqueous solution, the smudge of a sample printed on 10,000 sheets was evaluated. The results are shown in Table 2.

Banding evaluation ○: Banding is not seen ×: Image quality evaluation where banding is seen ○: Edge image has a sharp and uniform halftone image.
X: Unevenness is seen in the edge portion of the image and a non-uniform network image is formed.
Printing durability ○: 150,000 sheets or more ×: Less than 150,000 sheets stain evaluation ○: Very good ×: Halftone dot clogging or non-image area is stained

In order to evaluate the stability, Samples 1 to 8 were heated for 2 months in a heating machine with a temperature of 38 ° C. and a humidity of 80% RH, and the banding property and printing stain property were evaluated in the same manner as in the above test. The results were the same, and Samples 1 to 6 and 8 of the present invention showed good platemaking properties and printability. The comparison 7 was a worse level than before heating by heating for 2 months with a heater at a temperature of 38 ° C. and a humidity of 80% RH.

  From the above results, it can be seen that the photosensitive lithographic printing plate of the present invention prevents banding by plate making in a multi-channel infrared scanning exposure apparatus, and there is no clogging or smearing of the net image portion due to banding. It can also be seen that the provision of the overlayer of the present invention does not cause deterioration in image quality or adverse effects on printing durability. It can also be seen that the effect is stable and does not change even after storage over time.

Claims (2)

  On the support, an alkali-soluble polymer, a photopolymerization initiator, a photosensitive layer containing a sensitizing dye having absorption at 750 nm to 900 nm capable of sensitizing the photopolymerization initiator, and an overlayer on the photosensitive layer A photosensitive lithographic printing plate which is sequentially applied, wherein the overlayer contains a dye having absorption at least from 750 nm to 900 nm.   The alkali-soluble polymer is a polymer having an ethylenically unsaturated double bond in a side chain, a carboxyl group-containing monomer as a copolymerization component, and the photopolymerization initiator is an organic boron salt. The photosensitive lithographic printing plate according to claim 1.