JP5238279B2 - Processless planographic printing plate - Google Patents

Description

  The present invention relates to a processless lithographic printing plate having a plastic film as a support, and having a hydrophilic layer and an image forming layer at least in this order on the support. In particular, the image-forming layer is photosensitive and can be developed with water after exposure, or it can be mounted on a printing press after exposure to remove non-image areas by supplying ink and dampening water to the plate surface. Related to lithographic printing plates.

  With the digitization of the plate making system, there is an increasing demand for a printing plate suitable for a computer-to-plate system (referred to as a CTP system) that directly outputs data formatted on a computer screen to a planographic printing plate. In particular, a processless photosensitive lithographic printing plate that can be developed with water or developed on a printing machine, or a phase transition by heat, from a development system using special chemicals normally used in conventional printing plates near digital equipment. In addition, non-photosensitive processless lithographic printing plates having no development processing steps utilizing ink jets have attracted attention.

  In these CTP systems, since no special developing chemical is used, processing chemical costs are not required, or waste liquid processing costs are reduced, and at the same time, there is a merit of reducing environmental load. Furthermore, the printing system of the plastic film support has advantages that it can be supplied in rolls and is lighter and easier to handle than the printing plate of the aluminum support.

  As these CTP systems, for example, the wax in the image area is melted with a thermal head or a high-power near-infrared semiconductor laser to a printing plate coated with wax, and this becomes an oleophilic image area, and the wax is not dissolved. Processless lithographic printing plate in which the part remains hydrophilic, Processless lithographic printing plate that melts and fixes the image forming layer by heat, and removes the non-fixed part with water or a printing machine, or oleophilic with an inkjet head A processless lithographic printing plate that prints a substance on the surface of a printing plate in an image form is known.

  As a processless lithographic printing plate for printing an oleophilic substance on the plate surface in an ink jet manner, as described in JP-A-2007-144823 (Patent Document 1), a polymer having a sulfate group and a metal are used. It is disclosed to provide a hydrophilic layer containing an oxide. This publication discloses a hydrophilic layer having high film strength by crosslinking a polymer having a sulfate ester group with a polymer that reacts with a hydrophilic group and heating. On the other hand, Japanese Patent Application Laid-Open No. 2000-158839 (Patent Document 2) discloses a method in which an acrylic resin and colloidal silica are coated on a support at a certain ratio and heated.

  As described in JP-A-2006-281470 (Patent Document 3), a heat-melting lithographic printing plate includes a layer that becomes hydrophobic by heat, and a polyacrylic resin having an average molecular weight of 10,000 or more on the layer. A lithographic printing plate having a hydrophilic layer containing an acid is disclosed.

  In addition, as a processless lithographic printing plate in which an image forming layer is subjected to a crosslinking reaction by heat, an image forming layer containing a photothermal conversion agent is applied onto a support as disclosed in JP-A-2005-238527 (Patent Document 4). In addition, a method is disclosed in which a hydrophilic layer is applied thereon and the hydrophilic layer exposed to infrared rays is removed by water or on-machine development. In this case, the hydrophilic layer increases the film strength by crosslinking a polymer such as polyacrylic acid with an epoxy compound, and this hydrophilic layer is reacted with an N-alkyl or N-alkylene-substituted (meth) acrylamide compound that is not crosslinked. A method is disclosed in which the hydrophilic layer obtained in this manner is contained in a hydrophilic layer to prevent printing stains and speed up recovery of ink detachment.

  Further, there is a method in which a photopolymerizable photosensitive layer having photosensitivity to light of a specific wavelength is provided on a hydrophilic layer, and an unexposed portion is removed by water development or on-machine development after exposure. A photopolymerizable composition for obtaining such a photosensitive layer is described in JP-A No. 2003-215801 (Patent Document 5). According to the publication, a hydrophilic layer is provided on a plastic film support, on which a cationic water-soluble polymer having a phenyl group with a vinyl group substituted on the side chain, or a vinyl group substituted on the side chain. By applying a water-soluble polymer having a phenyl group and a sulfonate group, and a photosensitive layer characterized by containing a photopolymerization initiator or a photoacid generator, an unexposed portion is formed by exposure and subsequent water development. It is removed, and a lipophilic image part and a non-image part of the hydrophilic layer can be formed. As the hydrophilic layer, for example, a method of forming a hydrophilic layer by applying a (meth) acrylate monomer having a hydroxyalkyl group described in JP-B-49-2286 on a support and polymerizing by heating, JP, Contains a hydrophilic layer obtained by curing an acrylamide polymer described in JP-A-48-83902 with aldehydes, a water-soluble melamine resin described in JP-A-62-280766, polyvinyl alcohol, and a water-insoluble inorganic powder. A hydrophilic layer obtained by heat-curing the composition, a hydrophilic layer having an onium group described in JP-A-10-296895, and a crosslinked hydrophilic polymer having a Lewis base moiety described in JP-A-11-311861 Contains hydrophilic resin and water-dispersible filler obtained by three-dimensional crosslinking by interaction with polyvalent metal ions. Hydrophilic layer or the like are mentioned to.

In the various processless lithographic printing plates described above, in order for the formed image portion and non-image portion to have sufficient performance as a lithographic printing plate, the image portion is sufficiently adhered to the hydrophilic layer surface, It is necessary that the non-image area has sufficient hydrophilicity and that the non-image area itself is bonded to the support with sufficient strength. If this condition is not satisfied, a large number of prints may be caused due to poor printing durability due to peeling of the hydrophilic layer under the image area from the surface of the plastic film, or due to peeling of the hydrophilic layer surface of the non-image area from the surface of the plastic support. Printing stains may occur during sheet printing. Furthermore, even if the hydrophilic layer has good adhesion to the plastic support, if the hydrophilicity of the hydrophilic layer is not sufficient, ink will accumulate on the blanket surface by printing a large number of sheets, and the blanket will become dirty. Occurs, and further causes printing stains.
JP 2007-144823 A JP 2000-158839 A JP 2006-281470 A JP 2005-238527 A JP 2003-215801 A

  The object of the present invention is that a processless lithographic printing plate in which a hydrophilic layer and an image forming layer are provided on a plastic film support does not cause printing stains due to peeling of the hydrophilic layer even if a large number of sheets are printed. In addition, another object is to provide a processless lithographic printing plate having a good printing durability due to good adhesion between the hydrophilic layer and the image portion. It is another object of the present invention to provide a processless planographic printing plate that does not cause blanket stains even when a large number of sheets are printed.

The present invention has been achieved by the following invention.
1) On a plastic film support, it has a hydrophilic layer containing a water-soluble polymer and a compound having an epoxy group as a crosslinking agent for crosslinking the water-soluble polymer, and the following (1) to (3) In the processless lithographic printing plate having an image-forming layer formed by any of the above methods), the hydrophilic layer is a layer that acts as a non-image part during lithographic printing, and the water-soluble polymer is at least an epoxy A processless lithographic printing plate comprising a repeating unit which reacts with a group to form a crosslinked structure and a repeating unit having an ethyleneoxy group.
(1) A method in which a photopolymerizable photosensitive layer is provided on a hydrophilic layer and an unexposed portion is removed by water development or on-machine development after exposure.
(2) A method in which the image forming layer is melted and fixed on the hydrophilic layer by heat, and the non-fixed portion is removed with water or a printing machine.
(3) A method of printing an oleophilic substance on the surface of the plate surface in an image form with an inkjet head.
2) The processless lithographic printing plate as described in 1), wherein the water-soluble polymer further has a repeating unit having a hydrophilic group.
3) The processless lithographic printing plate according to 1) or 2), wherein the compound having an epoxy group is polyethylene glycol glycidyl ether.
4) The photopolymerizable photosensitive layer in the above method (1) is a cationic water-soluble polymer having a polymerizable double bond in the side chain, or a water solution having a polymerizable double bond in the side chain and having a sulfonic acid group. The processless lithographic printing plate according to any one of 1) to 3), which is a photosensitive layer containing a photopolymer and a photopolymerization initiator or photoacid generator.

  In the processless planographic printing plate in which a hydrophilic layer and an image forming layer are provided on a plastic film support according to the present invention, printing stains due to peeling of the hydrophilic layer do not occur even when a large number of sheets are printed. The processless lithographic printing plate having a good printing durability can be provided because of the good adhesion between and the hydrophilic layer. Furthermore, it is possible to provide a processless planographic printing plate in which blanket stains do not occur even when a large number of sheets are printed.

  The hydrophilic layer used in the processless lithographic printing plate of the present invention will be described. The water-soluble polymer of the present invention contained in the hydrophilic layer of the present invention needs to contain a reactive group in the molecule so that a crosslinking reaction can proceed efficiently with the epoxy compound described later. The term “water-soluble” as used herein means that the solubility in water is so high that an aqueous solution of 0.5% by mass or more can be obtained. Particularly preferred examples of the reactive group include a carboxyl group, an amino group, and a hydroxyl group. In order to obtain a water-soluble polymer having these reactive groups in the molecule, it is preferable to incorporate various monomers having the reactive groups in a copolymerized form. The water-soluble polymer of the present invention has a repeating unit that reacts with an epoxy group to form a crosslinked structure, and includes acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid. Carboxyl group-containing monomers such as acid, fumaric acid, cinnamic acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene, acrylamide-N-glycolic acid and their salts, allylamine, diallylamine, 2-dimethylamino Ethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene, 4-amino Amino group-containing monomers such as methylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, 4-vinylpyridine, 2-vinylpyridine , Nitrogen-containing heterocycle-containing monomers such as N-vinylimidazole, (meth) acrylamides such as N-methylolacrylamide and 4-hydroxyphenylacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, Examples thereof include hydroxyalkyl (meth) acrylates such as 2-hydroxypropyl methacrylate and glycerol monomethacrylate, and acetoacetoxy methacrylate, but are not limited to these examples.

  In the water-soluble polymer of the present invention, the proportion of the repeating unit that reacts with the epoxy group to form a crosslinked structure in the copolymer may be in the range of 1 to 40 in terms of mass ratio in the repeating unit. preferable. If it is less than this range, water resistance cannot be exhibited even if the crosslinking reaction proceeds. If this range is exceeded, the effect of hydrophilicity of the hydrophilic layer by introduction of ethyleneoxy group and the effect of adhesion between the image portion and the hydrophilic layer However, the stain resistance and printing durability due to printing may decrease.

  Next, the repeating unit having an ethyleneoxy group contained in the water-soluble polymer contained in the hydrophilic layer of the present invention includes methoxyethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol # 400 acrylate, Examples thereof include methoxypolyethylene glycol # 400 methacrylate, methoxypolyethylene glycol # 600 acrylate, methoxypolyethylene glycol # 600 methacrylate, and polyethylene glycol # 400 diacrylate, but are not limited to these examples.

  In the water-soluble polymer of the present invention, the ethyleneoxy repeat in the repeating unit having an ethyleneoxy group is preferably in the range of 1 to 14. If it exceeds this, the film strength after cross-linking may become weak regardless of the proportion of repeating units that react with the epoxy group to form a cross-linked structure. The proportion of the repeating unit having an ethyleneoxy group in the copolymer is preferably in the range of 1 to 90 in terms of the mass ratio of the repeating unit.

  Furthermore, in the water-soluble polymer of the present invention, it is preferable to introduce a monomer having a hydrophilic group into the repeating unit in order to further increase the hydrophilicity of the hydrophilic layer and prevent blanket contamination. The monomer having a hydrophilic group used for this purpose is preferably vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, 2-acrylamide-2- Sulfo group-containing monomers such as methylpropanesulfonic acid and salts thereof, phosphate group-containing monomers such as vinylphosphonic acid and salts thereof, dimethyldiallylammonium chloride, 2-trimethylammonium chloride, 2-trimethylammonium chloride , 2-triethylammonium ethyl acrylate chloride, 2-triethylammonium ethyl methacrylate chloride, 3-trimethylammonium propylacrylamide chloride, N, N, N-trimethyl chloride Quaternary ammonium salts such as (4-vinylbenzyl) ammonium, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-isopropylmethacrylamide, 3- (Meth) acrylamides such as dimethylaminopropylmethacrylamide, methacrylic acid methoxydiethylene glycol monoester, methacrylic acid methoxypolyethylene glycol monoester, and other alkyleneoxy group-containing (meth) acrylates such as methacrylic acid polypropylene glycol monoester, N-vinylpyrrolidone , N-vinylcaprolactam and the like, but are not limited thereto.

  Examples of preferred water-soluble polymers in the present invention are shown below.

  The average molecular weight of the water-soluble polymer is preferably 5,000 to 500,000, and more preferably 10,000 to 200,000. When the molecular weight is lower than this, the hydrophilic layer may dissolve or peel off when it comes into contact with water. On the other hand, if this range is exceeded, the viscosity of the coating liquid becomes high and uniform coating may not be possible.

The coating amount of the water-soluble polymers these hydrophilic layer contains is preferably 0.1-5 g / m ^2, more preferably from 0.3 to 3 g / m ^2.

  An epoxy compound is used as the crosslinking agent contained in the hydrophilic layer of the present invention. Such an epoxy compound is soluble in water or methanol or ethanol by at least 10% by mass. Such an epoxy compound is sold, for example, by Nagase ChemteX Corporation under the trade name “Denacol” and can be easily obtained. Preferred examples of the compound are given below.

  In particular, as an epoxy compound, polyethylene glycol glycidyl ether having the following structure is preferably used because it is excellent in printing stain due to peeling of the hydrophilic layer and printing durability due to peeling of the image portion and the hydrophilic layer. Examples are given below.

  There is a preferred range for the mass ratio between the various epoxy compounds as described above and the water-soluble polymer of the present invention. The crosslinking agent is preferably used in the range of 1 to 90 parts by mass with respect to the water-soluble polymer.

  The hydrophilic layer used in the present invention preferably contains colloidal silica in order to improve the adhesion of the image area and increase the hydrophilicity of the non-image area. The colloidal silica used in the present invention may be spherical, or a chain or pearl necklace colloidal silica is also preferably used.

The colloidal silica may be composed of a simple substance of SiO ₂ , but it is also possible to use a silica whose surface is slightly modified with Al ₂ O ₃ or the like in order to change the pH dependency of the dispersibility of silica. Further, depending on the pH of the coating liquid for the hydrophilic layer, an alkali dispersion or an acidic dispersion of colloidal silica can be selected and used.

  Examples of the spherical silica include “Snowtex XS”, “Snowtex S”, “Snowtex 20”, “MP-2040”, “MP-1040”, and “Snowtex ZL” manufactured by Nissan Chemical Industries, Ltd. Etc. These colloidal silicas have a pH of 9 or more, but when preparing an acidic coating liquid, it is possible to use “Snowtex O”, “Snowtex OL”, etc., which are made by demineralizing Na ions to make them acidic. I can do it. Examples of the chain silica include “Snowtex UP” manufactured by Nissan Chemical Industries, Ltd., and examples of the necklace-shaped silica include “Snowtex PS-S” and “Snowtex PS-M” manufactured by Nissan Chemical Industries, Ltd.

  The amount of colloidal silica contained in the hydrophilic layer is preferably such that the mass ratio of the water-soluble polymer of the present invention to colloidal silica is 1: 1 to 1: 4, more preferably 1: 1.5 to 1: 3. It is. A colloidal silica may add a single kind and may mix two or more sorts. When mixing, it is preferable that the mass ratio of the total solid content of colloidal silica and the polymer of this invention becomes the said mass ratio.

  In addition, dyes or pigments may be added to block light other than during exposure or to prevent halation. Furthermore, by adding inorganic fine particles such as titanium dioxide and silicon dioxide, it is possible to make the surface uneven, thereby improving the adhesion of the image area and improving the hydrophilicity of the non-image area.

  Further, in order to sufficiently crosslink the epoxy compound and the hydrophilic polymer of the present invention, conditions under a temperature of 40 to 100 ° C., preferably 45 to 80 ° C., before application of the image forming layer or coating of the photosensitive layer. And stored for 12 hours to 1 week, preferably 1 day to 5 days.

  On the hydrophilic layer of the present invention, the image forming layer is melted and fixed by heat, and the non-fixed portion is removed with water or a printing machine, or an oleophilic substance is printed on the surface of the plate surface in an image form with an inkjet head. An oleophilic image forming layer can be formed using a method or the like. As a preferable heat-meltable image forming layer, for example, a method using a heat-meltable fine particle compound described in JP-A-2007-175924 can be mentioned. Further, as a preferable ink composition for forming an image forming layer by an ink jet method, for example, an ink composition of a hot-melt solid ink mainly composed of wax as described in JP-A-2001-270261 or the like, or An ink composition containing an ultraviolet curable resin or a thermosetting resin as described in JP-A-56-10960, JP-A-5-204138, or the like, or described in JP-A-2004-66816, etc. And an ink composition containing a water-based ultraviolet curable resin.

  In the present invention, it is particularly preferable to use the following image forming layer in the adhesiveness of the image portion. The image forming layer preferably used in the present invention has a cationic water-soluble polymer having a polymerizable double bond in the side chain (hereinafter referred to as polymer A) or a polymerizable double bond and a sulfonic acid group in the side chain. A photosensitive layer containing a water-soluble polymer (hereinafter referred to as polymer B) and a photopolymerization initiator or photoacid generator.

  The polymer A used in the present invention represents a polymer in which a polymerizable double bond is introduced into a side chain in a water-soluble polymer having a cationic group. Hereinafter, the polymer A will be described in detail.

  The cationic group in the polymer A is a group selected from organic onium groups such as an ammonium group, a sulfonium group, a phosphonium group, an iodonium group, an oxonium group, and the quaternary ammonium group among these is most preferable.

  The above-mentioned polymer having an organic onium group introduced therein is disclosed in JP-B-55-13020, JP-A-55-22766, JP-A-11-153589, JP-A-2000-103179, US Pat. 693,958 and U.S. Pat. No. 5,512,418, can be synthesized using conventionally known chemical reactions. That is, a monomer containing a desired organic onium group is subjected to a polymerization reaction, or a trivalent N atom, a divalent S atom or a trivalent P atom introduced into a polymer chain constituting the polymer is usually used. The method of introduce | transducing an organic onium group by alkylation reaction of these is mentioned. Furthermore, the nucleophilic substitution reaction between a nucleophilic reagent such as amines, sulfides, and phosphines and a polymer chain-like leaving group (for example, sulfonic acid esters or halides) results in the polymer main chain or side chain. A method of introducing an organic onium group is also mentioned.

  As monomers for introducing a polymerizable double bond into the side chain of a polymer containing a polymerizable double bond, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl Examples include 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 thioacrylate, vinyl thio methacrylate, and the like. It is done.

  In the polymer A, a polymer having a phenyl group substituted with a vinyl group in the side chain, which has good adhesion between the image-formed portion after photopolymerization and the hydrophilic layer, is particularly preferable. In the present invention, the phenyl group substituted with a vinyl group is preferably introduced into the polymer via an appropriate linking group. In this case, the linking group is not particularly limited, and includes an arbitrary group, an atom, or a complex group thereof. Further, the vinyl group and the phenyl group may have a substituent. More specifically, the polymer introduced with a phenyl group substituted with a vinyl group has a group represented by the following general formula (I) in the side chain.

In the formula, R ₁ , R ₂ and R ₃ may be the same or different and are each a hydrogen atom, a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, or an alkyl group. Represents a group selected from aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group The alkyl group and aryl group constituting these groups are a halogen atom, carboxyl group, sulfo group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkenyl group, hydroxy group, alkoxy group, Aryloxy group, alkylthio group, arylthio group, alkylamino group , An arylamino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, and the like. Among these groups, those in which R ₁ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (for example, a methyl group, an ethyl group, etc.) and R ₂ and R ₃ are hydrogen atoms are particularly preferable.

In the formula, R ₄ is hydrogen atom, halogen atom, carboxyl group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, Represents a group selected from an arylamino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group and an arylsulfonyl group. The alkyl group and aryl group constituting these groups are a halogen atom, a carboxyl group, a sulfo group. Group, nitro group, cyano group, amide group, amino group, alkyl group, aryl group, alkenyl group, alkynyl group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, Acyl group, alkoxycarbonyl , An aryloxycarbonyl group, an alkylsulfonyl group, may be substituted by an arylsulfonyl group.

In the formula, m ₁ represents an integer of ₁ to 4, p represents 0 or 1, and q ₁ represents an integer of ₁ to 4.

In the formula, L ₁ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent linking group consisting of an atom group selected from a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom. Represent. Specific examples include groups composed of the structural units exemplified below and the heterocyclic groups shown below. These groups may be used alone or in any combination of two or more.

Examples of the heterocyclic ring constituting L ₁ include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thia Triazole ring, indole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline And a nitrogen-containing heterocycle such as a ring and a quinoxaline ring, a furan ring, a thiophene ring, and the like. These heterocycles may have a substituent.

  When the polyvalent linking group described above has a substituent, examples of the substituent include a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkenyl group, and an alkynyl group. Group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

The case where an organic onium group such as a quaternary ammonium group forming a cationic group is contained in any atomic group constituting the linking group L ₁ is particularly preferably used. In the case where such an organic onium group is not contained in the linking group, it is necessary to separately include a repeating unit having an organic onium group in the repeating unit constituting the main chain.

  The method for introducing a phenyl group substituted with a vinyl group into the polymer is not particularly limited. For example, Japanese Patent Publication No. 49-34041, Japanese Patent Publication No. 6-105353, Japanese Unexamined Patent Publication No. 2000-181062, Japanese Unexamined Patent Publication No. 2000-2000. Any method as disclosed in JP-A-187322 and the like may be used. In these cases, when a polymer as a precursor is synthesized in advance, a repeating unit having an organic onium group is introduced in the form of a copolymer, or a polymerizable unsaturated bonding group is introduced into the precursor polymer. In form, it is necessary to form an organic onium group, such as by the method described above.

  Specific examples of monomers that can constitute the polymer A include allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, 2-dimethylaminopropylacrylamide, and 3-dimethyl. Aminopropyl methacrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, etc. Amino group-containing monomers and quaternary ammonium salts thereof, nitrogen-containing heterocyclic ring-containing monomers such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole and the quaternary ammonium salts thereof (4 -Vini Benzyl) quaternary phosphonium salt monomers such as trimethylphosphonium bromide, tertiary sulfonium salt monomers such as dimethyl-2-methacryloyloxyethylsulfonium methosulfate, 2-chloromethylstyrene, 4-chloromethylstyrene, 4-bromomethylstyrene, Examples thereof include, but are not limited to, halogenated alkyl group-containing monomers such as 2-chloroethyl acrylate and 2-chloroethyl methacrylate.

  In addition, the polymer A may constitute a copolymer with any other monomer, and the monomer constituting the copolymer may be water-soluble or water-insoluble. Specific examples of water-soluble monomers include acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, cinnamic acid, maleic acid monoalkyl ester, fumaric acid Carboxyl group-containing monomers such as monoalkyl esters, 4-carboxystyrene, acrylamide-N-glycolic acid and their salts, phosphoric acid group-containing monomers such as vinylphosphonic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl Acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacryl Amino group-containing monomers such as amide, 4-aminostyrene, 4-aminomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-benzylbenzyl) amine, and the like; Nitrogen-containing heterocycle-containing monomers such as quaternary ammonium salts, 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole and the like, and quaternary ammonium salts thereof, acrylamide, methacrylamide, N, N -(Meth) acrylamides such as dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-isopropylmethacrylamide, diacetoneacrylamide, N-methylolacrylamide, 2-hydroxyethyl methacrylate, 2-hydroxy Propyl Examples include hydroxyalkyl (meth) acrylates such as acrylate, 2-hydroxypropyl methacrylate, and glycerol monomethacrylate, alkyleneoxy group-containing (meth) acrylates of methacrylic acid, N-vinylpyrrolidone, and N-vinylcaprolactam. It is not limited. These water-soluble monomers may be used alone or in combination of any two or more.

  In addition, in order to optimize water developability and improve the strength of the image area, it is also preferable to form a copolymer with any water-insoluble monomer. Examples of these include styrene, 4- Styrene derivatives such as methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-chloromethylstyrene, 4-methoxystyrene, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, Alkyl (meth) acrylates such as 2-ethylhexyl methacrylate, cyclohexyl acrylate and dodecyl methacrylate, aryl (meth) acrylates such as phenyl methacrylate and benzyl methacrylate, or arylalkyl (meth) acrylates , Acrylonitrile, methacrylonitrile, phenylmaleimide, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., vinyl ethers such as methyl vinyl ether, butyl vinyl ether, etc. Examples thereof include various monomers such as acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, and glycidyl methacrylate. A copolymer composed of any combination of these can be used as the polymer A.

  Arbitrary atomic groups constituting a linking group for bonding a phenyl group substituted with a vinyl group to the main chain include an organic onium group such as a quaternary ammonium group forming a cationic group. The case is most preferable. In this case, since the number of phenyl groups substituted with vinyl groups contained in the polymer is directly proportional to the number of organic onium groups, the phenyl groups substituted with vinyl groups contained in the polymer to improve sensitivity. Both can be satisfied at the same time. The unit structure of the polymer when the phenyl group substituted with the vinyl group as described above is bonded to the main chain through a cationic group can be specifically represented by the following general formula (II).

In the formula, A ₁ ⁺ represents an organic onium group such as an ammonium group, a sulfonium group, a phosphonium group, an iodonium group, an oxonium group, and n ₁ and n ₂ each represents 0 or 1. When A ₁ ⁺ is an iodonium group, n ₁ = n ₂ = 0, and when A ₁ ⁺ is a sulfonium group, n ₁ = 1 and n ₂ = 0, and A ₁ ⁺ is an ammonium group or a phosphonium group. In this case, n ₁ = n ₂ = 1.

In the formula, R ₅ and R ₆ may be the same or different, and are each an alkyl group (for example, methyl group, ethyl group, isopropyl group, cyclohexyl group, benzyl group) or an aryl group (for example, phenyl group, 1 -Naphthyl group and the like, and these groups may be substituted, and examples of the substituent in this case include a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, Alkyl group, aryl group, alkenyl group, alkynyl group, hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl Group, arylsulfonyl group and the like. Further, R ₅ and R ₆ may be a group containing a phenyl group substituted by a vinyl group represented by the general formula (II).

In the formula, R ₇ , R ₈ and R ₉ may be the same or different and have the same meanings as R ₁ , R ₂ and R ₃ in the general formula (I), respectively. Among these groups, those in which R ₇ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (for example, a methyl group, an ethyl group, etc.) and R ₈ and R ₉ are hydrogen atoms are particularly preferable. R ₁₀ has the same meaning as R ₄ in formula (I). L ₂ and L ₃ are each independently an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a multivalent group consisting of an atom group selected from a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom. Specifically, it is synonymous with L < ₁ > in the said general formula (I). m ₂ represents an integer of 0 to 4, p ₂ represents an integer of 0 or 1, and q ₂ represents an integer of 1 to 4.

A ring structure in which an N atom, an S atom, a P atom, or the like forming an organic onium group represented by A ₁ ⁺ is combined with a group arbitrarily selected from R ₅ , R _6, L ₂ , and L ₃ (For example, a pyridinium ring, 2-quinolium ring, morphonium ring, piperidinium ring, pyrrolidinium ring, tetrahydrothiophenium ring, etc.) may be formed. These ring structures are halogen atoms, carboxyl groups, sulfo groups, nitro groups, cyano groups, amide groups, amino groups, alkyl groups, aryl groups, alkenyl groups, alkynyl groups, hydroxy groups, alkoxy groups, aryloxy groups, alkylthio groups. , Arylthio group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

  Further, in the polymer A of the present invention, in addition to the polymer having a repeating unit in which a phenyl group substituted with a vinyl group as described above is bonded to the main chain through a cationic group, a vinyl group is substituted. It is also possible to use a polymer having a repeating unit in which the phenyl group is bonded directly or via a linking group containing no cationic group to the main chain and a repeating unit having a cationic group.

  Examples of the polymer A in the present invention are shown below, but the present invention is not limited to these examples. The numbers in the exemplified structural formulas represent the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  There exists a preferable range about the ratio for which each repeating unit which comprises the polymer A of this invention accounts in all the polymers. As described above, when a polymerizable double bond is bonded to the main chain via a cationic group on the side chain, the repeating unit is in the range of 10% to 80% by weight of the total polymer composition. This is particularly preferred.

  In the case of a polymer comprising a repeating unit in which a polymerizable double bond is bonded directly or via a linking group containing no cationic group to a main chain and a repeating unit having a cationic group, the polymerizable double bond is In the case of a repeating unit having a bond, it is particularly preferably in the range of 5% by mass to 50% by mass. The proportion of the repeating unit having a cationic group is preferably in the range of 30% by mass to 95% by mass, and particularly preferably in the range of 50% by mass to 90% by mass.

  There is a preferred range for the molecular weight of the polymer A of the present invention, the weight average molecular weight is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 10,000 to 300,000. The polymer A in this invention may be used individually by 1 type, and may mix and use arbitrary 2 or more types.

  Next, the water-soluble polymer (polymer B) having a polymerizable double bond and a sulfonic acid group in the side chain will be described in detail.

  The polymer B of the present invention is a polymer in which a polymerizable double bond and a sulfonate group are bonded to the main chain either directly or via an arbitrary linking group. These linking groups are not particularly limited, and include any group, atom, or a combination thereof. The polymerizable double bond and the sulfonate group may be independently bonded to the main chain, or the phenyl group substituted with the vinyl group and the sulfonate group share part or all of the linking group. You may combine with.

  As monomers for introducing a polymerizable double bond into the side chain of a polymer containing a polymerizable double bond, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl Examples include 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 thioacrylate, vinyl thio methacrylate, and the like. It is done.

  In the polymer B, like the polymer A, a polymer having a phenyl group substituted with a vinyl group and having good adhesion between the image-formed portion after photopolymerization and the hydrophilic layer is particularly preferable. The phenyl group substituted with a vinyl group is preferably introduced into the polymer via an appropriate linking group. In this case, the linking group is not particularly limited, and includes an arbitrary group, an atom, or a complex group thereof. Further, the vinyl group and the phenyl group may have a substituent. Examples of the substituent include a halogen atom, a carboxyl 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.

  More specifically, the polymer B of the present invention has groups represented by the following general formulas (III) and (IV) in the side chain.

In the formula, R ₁₁ , R ₁₂ , and R ₁₃ may be the same or different, and are respectively synonymous with R ₁ , R ₂ , and R _{3 in the} general formula (I). ₁₄ has the same meaning as in the general formula (I). L ₄ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or a polyvalent linking group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group; Is synonymous with L ₁ in the general formula (I). m ₃ represents an integer of 0 to 4, p ₃ represents 0 or 1, and q ₃ represents an integer of 1 to 4.

Among the groups represented by the above general formula, those in which R ₁₁ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.) and R ₁₂ and R ₁₃ are hydrogen atoms are preferred. . In addition, the linking group L ₄ preferably includes a heterocyclic ring, and q ₃ is preferably 1 or 2.

In the formula, L ₅ represents an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom or a polyvalent linking group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group, Specifically, it is synonymous with L < ₁ > in the said general formula (I). Further, L ₅ may share part or all of L _{4 in} the general formula (III).

In the formula, X ⁺ represents a cation having a charge necessary for neutralizing the sulfoanion. Specific examples of such cations include inorganic ions such as alkali metal ions, alkaline earth metal ions and transition metal ions (for example, sodium, potassium, calcium, magnesium, barium and zinc), organic ammonium ions (for example, ammonium, Triethylammonium, pyridinium, tetra-n-butylammonium, etc.), iodonium ions (eg, phenyliodonium, etc.), sulfonium ions (eg, triphenylsulfonium, etc.), diazonium ions, etc. Among these, alkali metal ions or organic ammonium ions Is particularly preferred.

  The method for introducing a phenyl group substituted with a vinyl group in the polymer is not particularly limited. However, when a monomer having a phenyl group substituted with a vinyl group is polymerized, the vinyl group also reacts to form a gel. It is anticipated that this will occur. Therefore, it is particularly preferable to synthesize a precursor polymer having no phenyl group substituted with a vinyl group, and then introduce a phenyl group substituted with the vinyl group by a conventionally known polymer reaction.

  The method for introducing the sulfonate group into the polymer is not particularly limited, and a monomer having the sulfonate group may be copolymerized, or a precursor polymer having no sulfonate group is synthesized, Thereafter, the sulfonate group may be introduced by a conventionally known polymer reaction.

  The polymer B of the present invention may be a polymer composed only of the above-described repeating unit having a polymerizable double bond in the side chain and a repeating unit having a sulfonate group, or hinders the effect of the present invention. As long as there is not, the polymer which introduce | transduced another repeating unit may be sufficient. Furthermore, it may be a copolymer with another monomer, and specific examples of such a monomer include all the water-soluble monomers and water-insoluble monomers exemplified in the polymer A. One type may be used, or two or more types may be used.

  Examples of the polymer B of the present invention are shown below, but the present invention is not limited to these examples. The numbers in the exemplified structural formulas represent the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The weight average molecular weight of the polymer B of the present invention is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 10,000 to 300,000. The polymer B in this invention may be used individually by 1 type, and may mix and use arbitrary 2 or more types.

  There is a preferred range for the solubility of the aforementioned polymers A and B of the present invention in water. That is, 0.5 g or more of the polymer is preferably dissolved in 100 ml of ion-exchanged water at 25 ° C., more preferably 2.0 g or more.

  The photosensitive layer of the present invention can be used by mixing any known various binder resins in addition to the polymer A or B described above. The binder resin in this case is not particularly limited, and specifically, a polymer arbitrarily constituted from the monomers exemplified above, polyvinylphenol, phenol resin, polyhydroxybenzal, gelatin, polyvinyl alcohol, carboxymethylcellulose, etc. Cellulose resin, polyimide resin, and the like. These binder resins are preferably water-soluble, and are water-soluble binder resins using at least one or more water-soluble monomers as exemplified above, and water-soluble binder resins such as gelatin, polyvinyl alcohol, and carboxymethyl cellulose. Is preferred.

  The image portion of the lithographic printing plate of the present invention contains a photopolymerization initiator or a photoacid generator in combination with the polymer A or B described above. As a photoinitiator used for this invention, arbitrary compounds can be used if it is a compound which can generate | occur | produce a radical by irradiation of light or an electron beam.

  Examples of photopolymerization initiators that can be used in the present invention include (a) aromatic ketones, (b) aromatic onium compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e And ketoxime ester compounds, (f) azinium compounds, (g) active ester compounds, (h) metallocene compounds, (i) trihaloalkyl-substituted compounds, (j) organoboron compounds, and the like.

  (A) Preferred examples of aromatic ketones include compounds having a benzophenone skeleton or a thioxanthone skeleton described in “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” JPFOUASSIER, JFRABEK (1993), P. 77 to P. 177. Α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, and JP-B-47. Benzoin derivatives described in JP-A-236364, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, Benzoin ethers described in JP-A No. 62-81345 and JP-A No. 2-211452 P-di (dimethylaminobenzoyl) benzene described in JP-A-61-194062, a thio-substituted aromatic ketone described in JP-A-61-194062, an acylphosphine sulfide described in JP-B-2-9597, and JP-B-2-9596 Examples thereof include acylphosphines described in JP-A No. 63-61950, thioxanthones described in JP-B No. 63-61950, and coumarins described in JP-B No. 59-42864.

  (B) Examples of aromatic onium salts include N, P, As, Sb, Bi, O, S, Se, Te, or I aromatic onium salts. Examples of such aromatic onium salts include compounds exemplified in Japanese Patent Publication No. 52-14277, Japanese Patent Publication No. 52-14278, Japanese Patent Publication No. 52-14279, and the like.

  Examples of (c) organic peroxides include almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. For example, 3,3 ′, 4,4′-tetra- (tert- Butyl peroxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (tert-amylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (tert-hexylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra (tert-octylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (cumylperoxycarbonyl) benzophenone, 3,3 ', 4,4'- Peracids such as tetra (p-isopropylcumylperoxycarbonyl) benzophenone and di-tert-butyldiperoxyisophthalate Ester is preferable.

  (D) Examples of hexaarylbiimidazole include lophine dimers described in JP-B Nos. 45-37377 and 44-86516, such as 2,2′-bis (o-chlorophenyl) -4,4. ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-bromophenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o, p -Dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetra (m-methoxyphenyl) biimidazole 2,2'-bis (o, o'-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-nitrophenyl) -4,4', 5 , 5 ' Tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-trifluoromethylphenyl) -4, Examples include 4 ', 5,5'-tetraphenylbiimidazole.

  (E) Examples of ketoxime esters include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2-acetoxyiminopentane- 3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutan-2-one, 2- And ethoxycarbonyloxyimino-1-phenylpropan-1-one.

  Examples of (f) azinium salt compounds include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, JP-B-46. The compound group which has NO bond as described in -42363 gazette etc. can be mentioned.

  (G) Examples of active ester compounds include imide sulfonate compounds described in JP-B-62-2623, etc., and active sulfonates described in JP-B-63-14340, JP-A-59-174831, etc. I can do it.

  (H) Examples of metallocene compounds include JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, and JP-A-2-4705. And titanocene compounds described in JP-A-1-304453, and iron-arene complexes described in JP-A-1-304453, JP-A-1-152109, and the like.

  (I) Specific examples of the trihaloalkyl-substituted compound include compounds having at least one trihaloalkyl group such as a trichloromethyl group and a tribromomethyl group in the molecule. US Pat. No. 3,954,475 Specification, U.S. Pat. No. 3,987,037, U.S. Pat. No. 4,189,323, JP-A-61-151644, JP-A-63-298339, JP-A-4-69661 And trihalomethyl-s-triazine compounds described in JP-A-11-153859, JP-A-54-74728, JP-A-55-77742, JP-A-60-138539, 2-Trihalomethyl-1,3 described in JP-A-61-143748, JP-A-4-362644, JP-A-11-84649, etc. 4- oxadiazole derivatives. Moreover, the trihaloalkylsulfonyl compound as described in Unexamined-Japanese-Patent No. 2001-290271 etc. which this trihaloalkyl group couple | bonded with the aromatic ring or the nitrogen-containing heterocyclic ring through the sulfonyl group is mentioned.

  (J) Examples of the organic boron salt compound include JP-A-8-217813, JP-A-9-106242, JP-A-9-18885, JP-A-9-188686, JP-A-9-188710. Organoboron ammonium compounds described in JP-A-6-175561, JP-A-6-175564, JP-A-6-157623, and the like. Organoboron iodonium compounds described in JP-A-6-175553, JP-A-6-175554, etc., Organoboron phosphonium compounds described in JP-A-9-188710, JP-A-6-348011, JP-A-7- 128785, JP-A-7-140589, JP-A-7-2920 4 JP, organic boron transition metal coordination complex compound described in JP-A-7-306527 Patent Publication, and the like. Examples of the counter anion described in JP-A-62-143044 and JP-A-5-194619 include cationic dyes containing an organic boron anion.

  As the photopolymerization initiator related to the present invention, an organic boron salt is particularly preferably used. More preferably, an organic boron salt and a trihaloalkyl-substituted compound (for example, an s-triazine compound, an oxadiazole derivative, or a trihaloalkylsulfonyl compound as a trihaloalkyl-substituted nitrogen-containing heterocyclic compound) are used in combination.

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

In the formula, each of R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ may be the same or different, and represents an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. Represent. Of these, it is particularly preferred that one of R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ is an alkyl group and the other substituent is an aryl group.

  In the above-mentioned organoboron anion, a cation that forms a salt is simultaneously present. Examples of the cation in this case include alkali metal ions, onium ions, and cationic sensitizing dyes. Examples of onium salts include ammonium, sulfonium, iodonium and phosphonium compounds. When a salt of an alkali metal ion or onium ion and an organic boron anion is used, the photosensitivity in the wavelength range of light absorbed by the dye is imparted by adding a sensitizing dye separately. Further, when an organic boron anion is contained as a counter anion of the cationic sensitizing dye, photosensitivity is imparted according to the absorption wavelength of the sensitizing dye. However, in the latter case, it is preferable to further contain an organic boron anion as a counter anion of the alkali metal or onium salt.

  The organic boron salt used in the present invention is a salt containing the organic boron anion represented by the general formula (V) described above, and alkali metal ions and onium ions are preferably used as cations forming the salt. The Particularly preferable examples of the onium salt with an organic boron anion include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

  As the photoacid generator used in the present invention, any compound can be used as long as it is a compound that can be decomposed by irradiation with light or electron beam to generate a strong acid such as hydrochloric acid or sulfonic acid or an acid such as Lewis acid. I can do it. Examples of the photoacid generator that can be used in the present invention include (k) an aromatic diazonium salt compound, (l) o-nitrogen such as pivalic acid-o-nitrobenzyl ester and benzenesulfonic acid-o-nitrobenzyl ester. Sulfonic acid ester derivatives such as nitrobenzyl esters, (m) 9,10-dimethoxyanthracene-2-sulfonic acid-4-nitrobenzyl ester, pyrogallol trismethanesulfonate, naphthoquinonediazide-4-sulfonic acid esters, (n) Sulfones such as dibenzylsulfone and 4-chlorophenyl-4'-methoxyphenyldisulfone, (o) phosphate ester derivatives and (p) U.S. Pat. No. 3,332,936, JP-A-2-83638, JP-A-11-322707, JP-A-2000-1469, etc. Placing a sulfonyl diazomethane compounds and the like can be exemplified.

  In the present invention, a trihaloalkyl-substituted compound can be used as a photopolymerization initiator that realizes higher sensitivity and higher contrast when used with an organic boron salt. Specifically, the trihaloalkyl-substituted compound is a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule. As a preferable example, the trihaloalkyl group is a nitrogen-containing complex. Examples of the compound bonded to the ring group include s-triazine derivatives and oxadiazole derivatives, or trihaloalkylsulfonyl compounds in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocycle via a sulfonyl group. .

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

  The photopolymerization initiator and photoacid generator may be used alone or in any combination of two or more. Further, any photopolymerization initiator and any photoacid generator can be used in combination. The content of the photopolymerization initiator and the photoacid generator is preferably in the range of 1 to 100% by mass, more preferably in the range of 1 to 40% by mass, based on the amount of either the polymer A or B.

  As another preferable element constituting the photosensitive layer in the present invention, a polymerizable monomer having a polymerizable unsaturated bond group in the molecule can be exemplified. The polymerizable unsaturated bond group represents an ethylenically unsaturated double bond group that can contribute to a photopolymerization reaction or a photocrosslinking reaction by the action of a photopolymerization initiator or a photoacid generator. In particular, it is preferable to use a polyfunctional polymerizable monomer having two or more polymerizable unsaturated bond groups in the molecule. Examples of such polymerizable monomers include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene. Polyfunctional acrylate monomers such as glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylol propane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc. Methacrylate monomers, as well as itaconic acid monomers, crotonic acid monomers , Maleic acid ester monomers.

  Examples of other polymerizable monomers include styrene derivatives. The styrene derivative is preferably a compound having two or more vinylphenyl groups in the molecule. For example, 1,4-divinylbenzene, 1,4-diisopropenylbenzene, 1,4-bis (4-vinylbenzyloxy) benzene, 1,2,3-tris (4-vinylbenzyloxy) benzene, 3,5-tris (4-vinylbenzyloxy) benzene, 2,2-bis [4- (4-vinylbenzyloxy) phenyl] propane, 1,1,2,2-tetrakis [4- (4-vinylbenzyl) Oxy) phenyl] ethane, α, α, α ′, α′-tetrakis [4- (4-vinylbenzyloxy)] p-xylene, 1,2-bis (4-vinylbenzylthio) ethane, 1,4- Bis (4-vinylbenzylthio) butane, bis [2- (4-vinylbenzylthio) ethyl] ether, 2,5-bis (4-vinylbenzylthio) -1,3,4-thiadiazole, , 4,6-Tris (4-vinylbenzylthio) -1,3,5-triazine, N, N-bis (4-vinylbenzyl) -N-methylamine, N, N, N ′, N′-tetrakis (4-vinylbenzyl) -1,2-diaminoethane, N, N, N ′, N′-tetrakis (4-vinylbenzyl) -p-phenylenediamine, maleic acid bis (4-vinylbenzyl) ester, etc. It is done.

  Alternatively, a polymerizable oligomer having radical polymerizability can be preferably used instead of the above polymerizable monomer. For example, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, and the like can be used in the same manner as the polymerizable monomer as various oligomers into which acryloyl group and methacryloyl group are introduced.

  Among the photosensitive layers using the polymer A and the polymer B described above, a photosensitive composition using the polymer B is particularly preferable because the strength of the image area is particularly excellent. When the photosensitive layer made of the polymer B is used as a processless lithographic printing plate, it is particularly suitable for printing on a printing machine without performing a development process, and a processless having excellent printing durability. A lithographic printing plate can be obtained.

  When a photosensitive layer is used in the processless lithographic printing plate of the present invention, it is possible to give sensitivity to light of various wavelengths by adding a dye to the photosensitive layer.

  As sensitizing dyes at 700 to 900 nm, cyanine, phthalocyanine, merocyanine, coumarin, porphyrin, spiro compound, ferrocene, fluorene, fulgide, imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, Coumarin, ketocoumarin, quinacridone, indigo, styryl, squarylium compound, pyrylium compound, and further, European Patent No. 0,568,993, US Pat. No. 4,508,811, US Pat. No. 5, The compounds described in the specification of 227,227 can also be used.

  Specific examples of sensitizing dyes that can be preferably used are shown below, but the present invention is not limited thereto. Sensitizing dyes corresponding to near-infrared light in the vicinity of 700 to 900 nm are shown below.

  There is a preferable range for the content of the sensitizing dye as described above, and it is preferable to add in the range of 1 to 300 mg per square meter of the photosensitive composition, and further, 5 to 200 mg per square meter of the photosensitive composition. It is particularly preferable to add in the range.

  In the processless lithographic printing plate of the present invention, it is also preferable to add other components for various purposes in addition to the components described above. In particular, it is preferable to add various polymerization inhibitors for the purpose of preventing thermal polymerization or thermal crosslinking of the polymerizable unsaturated bonding group and improving the long-term storage stability. As the polymerization inhibitor in this case, compounds having various phenolic hydroxyl groups such as hydroquinones, catechols, naphthols, and cresols, quinone compounds, and the like are preferably used, and hydroquinone is particularly preferably used. In this case, the addition amount of the polymerization inhibitor is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer.

  As another element when a photosensitive layer is applied to a processless lithographic printing plate, a colorant can be preferably added. As the colorant, it is used for the purpose of enhancing the visibility of the image area after exposure and development processing, such as carbon black, phthalocyanine dye, triarylmethane dye, anthraquinone dye, azo dye, etc. These dyes and pigments can be used, and it is preferably used in the range of 0.005 to 0.5 parts by mass with respect to 1 part by mass of the polymer.

  In addition to the above-mentioned elements, other elements can be added and added for various purposes as constituent elements when a photosensitive layer is applied to a processless lithographic printing plate. For example, inorganic fine particles or organic fine particles are preferably added for the purpose of preventing blocking of the photosensitive composition or improving the sharpness of an image after development.

  When a photosensitive layer is applied to a processless lithographic printing plate, a photosensitive composition coating liquid composed of the above-described elements is applied on a support and dried. As the coating method, various known methods can be used, and examples thereof include bar coater coating, curtain coating, blade coating, air knife coating, roll coating, spin coating, and dip coating. Regarding the thickness of the photosensitive layer itself when used as a 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. Is preferable in order to greatly improve.

  Examples of the plastic film support used as the support for the processless lithographic printing plate of the present invention include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyvinyl acetal, polycarbonate, cellulose diacetate, cellulose triacetate, and propion. Examples include acid cellulose, cellulose butyrate, and cellulose nitrate. The surface of these plastic film supports is subjected to various hydrophilization treatments for the purpose of improving the adhesion with the hydrophilic layer and providing water retention to the non-image area. Such hydrophilic treatment includes chemical treatment, discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, high-frequency treatment, active plasma treatment, laser treatment, and other surface treatments, and a hydrophilic layer is coated on the surface. The method etc. are mentioned, You may implement these processes in combination.

  The photosensitive image forming layer formed on the hydrophilic layer as described above is subjected to contact exposure or laser scanning exposure, and then a pattern is formed by removing an unexposed portion with a developer. The exposed portion is cross-linked, so that the solubility in a developing solution is lowered and an image portion is formed.

  The photosensitive image forming layer in the processless photosensitive lithographic printing plate of the present invention is characterized in that it can be developed with water. The developer used for water development is substantially free of an alkali agent, unlike a strong alkali developer (usually exceeding pH 10) which contains a large amount of an alkali agent generally used conventionally. Therefore, the pH of the developer used in the water development of the present invention is 10 or less, preferably pH 9.5 or less, and more preferably pH 9 or less. The lower limit of pH is about 3. The developer used in the water development of the present invention is such that water accounts for 70% by mass or more, more preferably 80% by mass or more of the total developer, and other additives include ethanol, isopropanol, and n-butyl cellosolve. Further, various organic solvents such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin and benzyl alcohol, or anionic, cationic and nonionic surfactants can be added.

  Next, typical synthesis examples of the water-soluble polymer used in the hydrophilic layer of the present invention will be given, but other exemplified compounds can be easily synthesized by referring to the same method or a conventionally known method as described above. I can do it. The method for synthesizing the polymer of the photosensitive layer can be synthesized according to the synthesis example described in JP-A-2003-215301.

Synthesis example 1
Synthesis Example of Hydrophilic Polymer (WP-7) Sodium styrenesulfonate (120 g) was weighed into a 1-liter four-necked flask equipped with a reflux tube, a nitrogen introduction tube, a thermometer and a stirrer, and ethanol (100 g ) And pure water (500 g) were added and stirred. To this was added phosphoric acid (27.7 g) at room temperature. Next, dimethylaminoethyl methacrylate (40 g) was added, and further methoxypolyethylene glycol # 400 methacrylate (40 g) was added and stirred and dissolved. The mixture was transferred to a 75 ° C. water bath under a nitrogen atmosphere and stirred. When the internal temperature reached 70 ° C., 1.4 g of azobisamidinopropane dihydrochloride was added to initiate polymerization, and heat generation was observed 10-30 minutes after the start of polymerization, and ethanol reflux was observed. . Stirring was continued for 4 hours after the start of polymerization while maintaining the internal temperature at 75 ° C., and the obtained copolymer solution was used for evaluation as it was without purification. The average molecular weight of the hydrophilic polymer obtained here was about 100,000. Other related water-soluble polymers were basically synthesized by the same synthesis method.

  A hydrophilic layer coating solution having the following composition was prepared. Next, the coating solution was applied and dried on a polyethylene terephthalate film support having a gelatin undercoat layer having a thickness of 0.10 mm so as to have a dry thickness of 1.0 μm. This was put into a thermostat kept at 50 ° C. for 2 days to be crosslinked.

<Hydrophilic layer coating solution>
Polymer (described in Table 1) 3.1 parts by mass (solid content)
Cross-linking agent (described in Table 1) 0.47 parts by mass (solid content)
Colloidal silica (PS-M) 6.2 parts by mass (solid content)
Ethanol 10.0 mass parts It adjusted to 100 mass parts with water.

  The pH of the coating solution was adjusted to 8.0 using 1N sodium hydroxide and 1N sulfuric acid. The polymers and crosslinking agents used are listed in Table 1. All the polymers used here have an average molecular weight of approximately 100,000. As a comparative example, a polymer having the following structure and polyacrylic acid (average molecular weight 100,000) were used.

A coating solution for a photosensitive layer having the following composition was prepared, and then the coating solution was applied on each hydrophilic layer described in Table 1 so that the dry thickness was 1.0 μm, and dried at 70 ° C. for 2 minutes. A sample was prepared.
<Photosensitive layer coating solution>
Polymer A (CP-1) 3.0 parts by mass Photopolymerization initiator (BC-6) 0.5 parts by mass Photopolymerization initiator (T-4) 0.25 parts by mass Sensitizing dye (S-4) 0 .1 part by weight Blue pigment 0.1 part by weight 1,3-dioxolane 25.0 parts by weight Water 25.0 parts by weight

The above sample is wound around a photosensitive drum, exposed to a test pattern of 2400 dpi and 175 lines with a laser beam having a wavelength of 830 nm and a spot diameter of 20 μm at an exposure energy of 120 mJ / cm ² , and then immersed in water at 25 ° C. for 15 seconds. The photosensitive layer was rubbed with a cellulose sponge for development and dried.

  The sample was subjected to a printing test using an H234C (Hamada Printing Machinery Co., Ltd.) offset printing machine. The dampening solution used was a 1% by weight diluted solution of Toho Etch (Toho Seiki Co., Ltd.), and the ink used was New Champion Ink H (Dainippon Ink Chemical Co., Ltd.). Printing was performed up to 20000 sheets, and the printed material, the hydrophilic layer of the plate surface at that time, and the surface of the image part were observed with a 100 times magnifier and evaluated as follows. The hydrophilic layer was evaluated according to the following criteria. ○: No printing stain occurs and no change in the surface of the hydrophilic layer is observed. ○ Δ: The printed material is not stained, but the hydrophilic layer is slightly scratched. (Triangle | delta): Printing stain generate | occur | produces in a part of printed matter, and when the hydrophilic layer of the printing plate surface of the printing stain generate | occur | produced is observed, it is observed that the hydrophilic layer has peeled off. Δ: Stain is generated on the printed matter, and the image portion is missing on the printed matter. When the plate surface is observed, the hydrophilic layer is peeled off at the portion of the printed stain, and the image portion is hydrophilic at the missing portion of the image portion. It is observed that is peeled off. X: Print stains occur on the printed matter, and the image portion is missing. When the printing plate is observed, the hydrophilic layer is peeled off at the portion where the printing stain is generated, and the portion lacking the image portion is peeled off from the hydrophilic layer.

  Furthermore, the blanket stain after printing 20000 sheets was evaluated by the following criteria by attaching a cellophane tape to the non-image part of the blanket printed 20000 sheets and peeling it off. ○: Ink stains are not adhered to the cellophane tape. (Triangle | delta): Cellophane tape A little ink is attached. X: The cellophane tape is black, and when the printed material is viewed, the stain is slightly seen. The results are shown in Table 1.

  As can be seen from Table 1, in the sample of the comparative example, after printing 20000 sheets, stains in the non-image area and chipping in the image area occurred, and when the plate surface was observed, peeling of the hydrophilic layer and peeling of the image area were observed. On the other hand, with the sample of the present invention, the printed matter did not change even after printing 20000 sheets, and the plate surface did not change. Furthermore, the blanket stain did not occur in the polymer into which the hydrophilic group was introduced.

  A coating solution was prepared in the same manner as in Example 1 except that the polymer A used in the photosensitive layer coating solution of Example 1 was changed to the polymer B (SP-1). Was coated on a polyethylene terephthalate film support having a gelatin subbing layer of 0.1 mm. This sample was exposed and developed under the same conditions as in the example, a printing test was performed under the same conditions as in Example 1, and printing durability and printing stains were evaluated according to the same criteria. The results are shown in Table 2.

  As can be seen from Table 2, in the sample of the comparative example, as in Example 1, the non-image area was smeared and the image area was chipped after printing 20000 sheets. While peeling of the part was observed, in the sample of the present invention, the printed material did not change even after printing 20000 sheets, and the plate surface did not change. Further, when a hydrophilic layer using a polymer into which a hydrophilic group was introduced was used, blanket contamination did not occur. Moreover, compared with the evaluation result of Example 1 which used the polymer A for the photosensitive layer, the result better than Example 1 was obtained in Example 2 using the polymer B by printing evaluation.

An ink for an ink jet printer was prepared according to the following formulation, and printed on the comparative example of Example 1 and the hydrophilic layer of the present invention with an ink jet printer (PM-770C; manufactured by Seiko Epson Corporation). Since the head is clogged when the viscosity of the ink composition is high, an ultraviolet curable resin and denatured ethanol (ethanol 85.5% by mass, isopropyl alcohol 13.4) are adjusted so that the viscosity of the ink composition is 2 to 5 mPa · s. Mass%, ethyl acetate 1.1 mass%, boiling point 81 ° C.). After printing, the printed portion was exposed for 15 seconds with a high-pressure mercury lamp (80 W · cm ² , power supply 1 kW) to cure the ink composition.

<Ink composition for inkjet printer>
The following UV curable resin 25 parts by mass Edible blue No. 1 0.4 parts by mass Darocur 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one; manufactured by Ciba Specialty Chemicals Co., Ltd.)
2 parts by mass Denatured ethanol 52.6 parts by mass Water 20 parts by mass

  The sample was printed up to 10,000 sheets under the same printing conditions as in Example 1, and evaluated according to the same criteria as in Example 1. The results are shown in Table 3.

  As can be seen from Table 3, in the sample of the comparative example, after printing 10,000 sheets, stains in the non-image area and chipping in the image area occurred, and when the plate surface was observed, peeling of the hydrophilic layer and peeling of the image area were observed. On the other hand, in the sample of the present invention, the printed matter did not change even after printing 10,000 sheets, and the plate surface did not change. Furthermore, blanket stains did not occur in the hydrophilic layer using a polymer having a hydrophilic group introduced therein.

Claims (4)

A plastic film support has a hydrophilic layer containing a water-soluble polymer and a compound having an epoxy group as a crosslinking agent for crosslinking the water-soluble polymer, and further has the following (1) to (3) In a processless lithographic printing plate having an image forming layer formed by any method, the hydrophilic layer is a layer that acts as a non-image part during lithographic printing, and the water-soluble polymer has at least an epoxy group and A processless lithographic printing plate comprising a repeating unit which reacts to form a crosslinked structure and a repeating unit having an ethyleneoxy group.
(1) A method in which a photopolymerizable photosensitive layer is provided on a hydrophilic layer and an unexposed portion is removed by water development or on-machine development after exposure.
(2) A method in which the image forming layer is melted and fixed on the hydrophilic layer by heat, and the non-fixed portion is removed with water or a printing machine.
(3) A method of printing an oleophilic substance on the surface of the plate surface in an image form with an inkjet head. 2. The processless lithographic printing plate according to claim 1, wherein the water-soluble polymer further has a repeating unit having a hydrophilic group.   3. The processless lithographic printing plate according to claim 1, wherein the compound having an epoxy group is polyethylene glycol glycidyl ether. The photopolymerizable photosensitive layer in the method (1) is a cationic water-soluble polymer having a polymerizable double bond in the side chain or a water-soluble polymer having a polymerizable double bond in the side chain and having a sulfonic acid group. The processless lithographic printing plate according to any one of claims 1 to 3, which is a photosensitive layer containing a coalescence and a photopolymerization initiator or a photoacid generator.