JP2009241300A - Process-less photosensitive lithographic printing plate - Google Patents

Abstract

[PROBLEMS] To prevent the photosensitive layer and the backing layer from sticking or peeling off even when stored for a long time in a high humidity environment, and further, the deterioration of image quality due to reflection and scattering of light from the back is improved. Processless planographic printing plates.
SOLUTION: A hydrophilic layer and a cationic water-soluble polymer having a phenyl group substituted with a vinyl group on a side chain or a phenyl group substituted with a vinyl group on a side chain and a sulfonic acid group on a plastic film support. A water-soluble polymer and a photosensitive layer containing a photopolymerization initiator or photoacid generator in at least this order, and a metal oxide and carbon on the surface of the plastic film support opposite to the side having the photosensitive layer Processless photosensitive lithographic printing plate having a backing layer containing black.
[Selection figure] None

Description

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

  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 press from a development system that uses special chemicals normally used in conventional printing plates near a digital device, or a thermal phase. Non-photosensitive processless lithographic printing plates which have no development process using transfer or ink jet 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 for the plastic film support is advantageous in that it can be supplied in rolls and is lighter and easier to handle than the printing plate on 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 becomes hydrophilic, processless lithographic printing plate in which the image forming layer is melted and fixed by heat, and the non-fixed part is removed with water or a printing machine, or an oleophilic substance is removed with an inkjet head Processless planographic printing plates that print on the plate surface in an image form are known.

  As described in JP-A-2007-144823, the processless lithographic printing plate for printing an oleophilic substance on the plate surface in an image form by an ink jet method contains a polymer having a sulfate ester group and a metal oxide. A processless lithographic printing plate provided with a hydrophilic layer is disclosed. Japanese Patent Application Laid-Open No. 2000-158839 discloses a processless lithographic printing plate in which an acrylic resin and colloidal silica are coated on a support at a certain ratio and heated to provide a hydrophilic layer.

  As described in JP-A-2006-281470, as a hot-melt lithographic printing plate, a hydrophilic layer containing a layer that becomes hydrophobic by heat and a polyacrylic acid having an average molecular weight of 10,000 or more is formed thereon. A processless lithographic printing plate having a conductive layer is disclosed.

  In addition, as a processless lithographic printing plate in which an image forming layer is subjected to a crosslinking reaction by heat, as in JP-A-2005-238527, an image forming layer containing a photothermal conversion agent is applied on a support, A method is disclosed in which a hydrophilic layer is applied and the hydrophilic layer exposed at infrared rays is removed by water or on-machine development.

  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 1). According to the publication, a hydrophilic layer is provided on a plastic film support, and 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 photosensitive layer characterized by containing a water-soluble polymer having a phenyl group and a sulfonate group, and a photopolymerization initiator or an acid generator, an unexposed portion can be obtained by exposure and subsequent water development. Is removed, and a lipophilic image portion and a non-image portion of the hydrophilic layer can be formed.

  The use of the photopolymerizable photosensitive layer has an advantage that an image can be obtained with lower energy compared to, for example, an image forming method using heat. Furthermore, it is possible to obtain a high-definition printing plate as compared with an ink jet, and further to obtain a high-quality printed matter by using this.

  However, since the photopolymerizable photosensitive layer contains a highly water-soluble polymer, it is highly hygroscopic, and when stored under high humidity conditions, for example, in the form of a roll or in the form of a sheet There is a problem that the photosensitive layer and the support adhere to each other or the photosensitive layer is transferred to the support. Usually, the opposite side of the side having the photosensitive layer having the support is added with fine particles in the backing layer in order to facilitate fine adjustment of the alignment when the printing plate is wound around the cylinder of the printing press. A conductive material is added to the backing layer to make it slippery with respect to the cylinder of the printing press, or to prevent static electricity from being generated. There is a problem that the coating layer sticks and the photosensitive layer peels off.

Furthermore, since most plastic film supports are different from aluminum supports in that they have at least a light transmission property, when a hydrophilic layer is provided on the plastic film support and a photosensitive layer is further provided, the back side is exposed during exposure. There is a problem that the image quality of the image obtained by the reflection and scattering of light from the light deteriorates.
JP 2003-215801 A

  The object of the present invention is to prevent the photosensitive layer and the backing layer from sticking or peeling off even if stored for a long time in a high humidity environment, and further to reduce the image quality due to light reflection and scattering from the back side. Is to provide an improved processless lithographic printing plate.

The present invention has been achieved by the following invention.
Water-soluble polymer containing a hydrophilic layer on a plastic film support and a cationic water-soluble polymer having a phenyl group substituted with a vinyl group on the side chain or a phenyl group substituted with a vinyl group on the side chain and a sulfonic acid group And a photosensitive layer containing at least a photopolymerization initiator or a photoacid generator in this order, and containing a metal oxide and carbon black on the surface of the plastic film support opposite to the side having the photosensitive layer. Processless photosensitive lithographic printing plate with a backing layer.

  According to the present invention, there is no sticking of the photosensitive layer and the backing layer even when stored for a long time in a high humidity environment, and the photosensitive layer is not peeled off from the front surface. Further, the image quality is deteriorated due to reflection and scattering of light from the back side. Can provide an improved processless planographic printing plate.

  In the present invention, the metal of the metal oxide includes metals and metalloids, such as sodium, magnesium, aluminum, potassium, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, strontium, zirconium, Examples include molybdenum, tin, indium, and barium.

Suitable examples of such metal oxides include MgO, Al ₂ O ₃ , TiO ₂ , V ₂ O ₅ , ZnO, ZrO ₂ , MoO ₃ , SnO ₂ , In ₂ O ₃ , BaTiO ₃ , and SrTiO ₃ . Of these, Al2O3 and TiO2 are preferable. These metal oxides are, for example, commercially available products such as alumina (for example, A32 and A33F manufactured by Nippon Light Metal Co., Ltd., AES11, AES-12 and AES-23 manufactured by Sumitomo Chemical Co., Ltd., manufactured by Showa Denko KK A-43M, A-50K, etc.), titanium oxide (for example, R-780, R-830, CR-50 manufactured by Ishihara Sangyo Co., Ltd., TA100, TA200, TA300 manufactured by Fuji Titanium Industrial Co., Ltd.), etc. Fine particles.

  These metal oxides can be used alone or in combination of two or more. When using 2 or more types together, it can also be added as fine particles of these mixtures.

As the fine particles of the above mixture, natural mineral fine particles containing at least one of metal oxides in the composition are also preferably used. Examples thereof include kaolin (main components: SiO ₂ , Al ₂ O ₃ , and H ₂ O), pumice (main components: SiO ₂ , Al ₂ O ₃ ), and talc (main components: SiO ₂ , MgO).

  The average particle size of the metal oxide used in the present invention is preferably from 0.01 to 30 μm, and preferably from 0.1 to 5 μm. Moreover, it is preferable that it is 10-60 mass% with respect to the total solid content which a backing layer contains, and, as for content of the metal oxide in a backing layer, 20-50 mass% is more preferable.

  In addition, the metal oxide may be subjected to various surface treatments as necessary. The surface treatment can be appropriately selected according to the purpose from, for example, a hydrophilic treatment with an alkali silicate aqueous solution, a dispersion stabilization with a surfactant, and the like.

  The backing layer of the present invention is a binder for stably dispersing the metal oxide in addition to the above-described metal oxide and preventing the metal oxide from being removed from the support by friction after coating. It is preferable to contain. Examples of the binder include synthetic polymer compounds such as acrylic resin, vinyl resin, polyurethane resin, and polyester resin, and natural polymer compounds such as gum arabic, starch, and gelatin. In the present invention, these may be emulsions dispersed in a solvent such as water or an organic solvent. As the binder used in the present invention, gelatin is preferably used.

  When gelatin is used as the backing layer of the present invention, other synthetic or natural polymer compounds or emulsions can be used in combination. Further, the backing layer preferably contains a cross-linking agent. Examples of the crosslinking agent include inorganic compounds such as chrome alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, and 2,3-dihydroxy-1 , 4-dioxane, 2,4-dichloro-6-hydroxy-s-triazine salt, compounds having active halogen such as 2,4-dichloro-6-hydroxy-s-triazine salt, divinyl sulfone, divinyl ketone, Various compounds such as N, N, N-triacroylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups and epoxy groups in the molecule, and dialdehyde starch as a polymer hardener These compounds can be used alone or in combination of two or more.

  The content of the binder in the backing layer is preferably 5 to 60% by mass and more preferably 10 to 50% by mass with respect to the total solid content contained in the backing layer. If it is the said range, since the roughness of the surface is kept moderate and the above-mentioned metal oxide appears on the surface of the backing layer, the photosensitive layer does not stick to the backing layer.

  Further, the backing layer of the present invention contains carbon black. Such carbon black is not particularly limited in particle size, structure, and surface shape, but those having a small particle size and good dispersibility are preferably used because of high hiding power. However, if the addition amount is large, the visibility of the image area on the printed surface may be lowered, so the minimum necessary addition amount is good. Specifically, carbon black having a particle diameter of 5 to 100 nm is preferably contained in the backing layer in an amount of 0.1 to 5% by mass, preferably 1 to 4% by mass.

  Further, various additives can be appropriately added to the backing layer. A dye or pigment for coloring, an anionic or cationic surfactant for improving coatability, and an oil or fat compound for improving slipperiness can be added.

  The thickness of the backing layer of the present invention is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

  The processless lithographic printing plate of the present invention has a hydrophilic layer on a support and a photosensitive layer thereon. Specifically, the hydrophilic layer used in the present invention contains a hydrophilic polymer and hydrophilic inorganic fine particles, and further, the hydrophilic polymer is cross-linked with a cross-linking agent to thereby adhere the hydrophilic layer to the support. It is possible to secure the strength against printing. As the hydrophilic polymer constituting the hydrophilic layer, it is preferable to use a copolymer of at least a monomer having hydrophilicity and a monomer capable of undergoing a crosslinking reaction with a crosslinking agent. Examples of the monomer for imparting hydrophilicity include anionic, cationic and other ionic monomers. Specifically, sulfo group-containing monomers such as vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, and 2-acrylamido-2-methylpropane sulfonic 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 chloride, chloride 2-triethylammonium ethyl methacrylate, 3-trimethylammonium propylacrylamide chloride, 3-dimethylaminopropylmethacrylamide, N, N, N-trimethyl-N-chloride (Meth) such as quaternary ammonium salts such as 4-vinylbenzyl) ammonium, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-isopropylmethacrylamide Examples include acrylamides, alkyleneoxy group-containing (meth) acrylates such as methacrylic acid methoxydiethylene glycol monoester, methacrylic acid methoxypolyethylene glycol monoester, and methacrylic acid polypropylene glycol monoester, N-vinylpyrrolidone, and N-vinylcaprolactam. It is not limited to these.

  Examples of the monomer that undergoes a crosslinking reaction with the crosslinking agent include monomers having a carboxyl group, an amino group, a hydroxyl group, and an acetoacetoxy group, and particularly preferred examples include a carboxyl group, an amino group, and a hydroxyl group. In order to obtain a hydrophilic polymer having these reactive groups in the molecule, it is preferable to incorporate various monomers having the reactive groups in a copolymerized form. Such 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 monoalkyl ester, Carboxyl group-containing monomers such as 4-carboxystyrene and acrylamide-N-glycolic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 3-dimethylamino Propylacrylamide, 3-dimethylaminopropylmethacrylamide, 4-aminostyrene, 4-aminomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine Amino group-containing monomers such as N, N-diethyl-N- (4-vinylbenzyl) amine, nitrogen-containing heterocycle-containing monomers such as 4-vinylpyridine, 2-vinylpyridine and N-vinylimidazole, N-methylolacrylamide, (Meth) acrylamides such as 4-hydroxyphenylacrylamide, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, glycerol monomethacrylate and the like; Examples include acetoacetoxy methacrylate. Examples of preferred hydrophilic polymers are shown below.

  The average molecular weight of the hydrophilic 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 it exceeds this range, the viscosity of the coating liquid becomes high and uniform coating may not be possible.

  Examples of the crosslinking agent used for the hydrophilic layer include an epoxy compound, a compound having an oxazoline group, and a compound having an isocyanate group. The epoxy compound used in the present invention is soluble in water, methanol or ethanol, and preferably has a hydrophilic group and two or more epoxy groups in the molecule. These compounds are sold by Nagase ChemteX Corporation under the trade name “Denacol” and can be easily obtained.

  In order for the crosslinking reaction to proceed efficiently between the epoxy compound and the hydrophilic polymer as described above, the reactive group contained in the hydrophilic polymer is particularly preferably a carboxyl group or an amino group.

  As the oxazoline compound, a compound containing two or more of the following groups as substituents in the molecule is preferable. Examples of commercially available compounds include various grades provided by Nippon Shokubai Co., Ltd. under the trade name “Epocross”. These compounds are preferably used. In order for the crosslinking reaction to proceed efficiently between such an oxazoline compound and the water-soluble polymer, a carboxyl group is particularly preferred as the reactive group contained in the hydrophilic polymer.

  As the isocyanate compound, a compound that is stable in water is preferable, and a so-called self-emulsifiable isocyanate compound or a blocked isocyanate compound is preferably used. Examples of the self-emulsifying isocyanate compound include Japanese Patent Publication No. 55-7472 (U.S. Pat. No. 3,996,154) and Japanese Patent Laid-Open No. 5-222150 (U.S. Pat. No. 5,252,696). Self-emulsifiable isocyanate as described in JP-A-9-71720, JP-A-9-328654, JP-A-10-60073, and the like. Specifically, for example, a polyisocyanate having an isocyanurate structure of a cyclic trimer skeleton formed from an aliphatic or alicyclic diisocyanate in the molecule, or a polyisocyanate having a burette structure, a urethane structure or the like in the molecule. A very preferable example is a polyisocyanate compound having a structure obtained by adding a polyethylene glycol or the like having one terminal etherification to only a part of the polyisocyanate group as a base polyisocyanate. A method for synthesizing an isocyanate compound having such a structure is described in the above specification. Specific examples of such isocyanate compounds are commercially available in which polyisocyanates obtained by cyclic trimerization using hexamethylene diisocyanate or the like as a starting material are used as base polyisocyanates. And so on. The blocked isocyanate compound is blocked with bisulfite, alcohols, lactams, oximes, active methylenes, etc. as seen in, for example, JP-A-4-184335 and JP-A-6-175252. Blocked isocyanate is preferably used. In order for the crosslinking reaction to proceed efficiently between such an isocyanate compound and the water-soluble polymer, the reactive group contained in the hydrophilic polymer is particularly preferably a hydroxyl group or an amino group.

  There is a preferred range for the ratio of the various crosslinking agents and hydrophilic polymers as described above. The crosslinking agent is preferably used in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the hydrophilic polymer. Any of the various crosslinking agents described above is preferably used, but a particularly preferred crosslinking agent is an epoxy compound.

  As the hydrophilic inorganic fine particles contained in the hydrophilic layer, colloidal silica is preferably used from the viewpoint of improving the adhesiveness of the image area and increasing 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. Also, depending on the pH of the coating liquid of 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”, “Snowtex-ZL” manufactured by Nissan Chemical Co., Ltd. It is done. These colloidal silicas have a pH of 9 or more. However, when creating an acidic coating solution, use “Snowtex O”, “Snowtex-OL”, etc., which is made by demineralizing Na ions to make it acidic. You can also. Examples of the chain silica include “Snowtex UP” manufactured by Nissan Chemical Industries, and examples of the pearl necklace-like silica include “Snowtex PS-S” and “Snowtex PS-M”.

  The amount of colloidal silica contained in the hydrophilic layer is preferably such that the mass ratio of the hydrophilic polymer and colloidal silica is 1: 1 to 1: 4, more preferably 1: 1.5 to 1: 3. . 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, the hydrophilic layer may contain a dye or a pigment in order to block light other than during exposure or prevent halation. Furthermore, by adding inorganic fine particles such as titanium oxide and silicon dioxide, irregularities can be made on the surface, thereby improving the adhesion of the image area and improving the hydrophilicity of the non-image area.

  The hydrophilic layer is produced by applying and drying a coating liquid of a composition composed of the above-described elements on a support. 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 0.3 μm to 10 μm, and more preferably in the range of 0.5 μm to 5 μm. .

  Further, in order to sufficiently crosslink the cross-linking agent and the hydrophilic polymer, before coating the photosensitive layer, the temperature is 40 to 100 ° C., preferably 45 to 80 ° C. for 12 hours to 1 week, preferably 1 It is preferable to store for 5 days.

  The photosensitive layer of the present invention comprises a cationic water-soluble polymer having a phenyl group substituted with a vinyl group in the side chain (hereinafter referred to as polymer A) or a phenyl group and a sulfonic acid group substituted with a vinyl group in the side chain. It contains 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 phenyl group substituted with a vinyl group 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, and an oxonium group, and among these, a quaternary ammonium group is most preferable.

  The above-mentioned polymer A into which an organic onium group has been introduced is disclosed in JP-B-55-13020, JP-A-55-22766, JP-A-11-153859, JP-A-2000-103179, US Pat. No. 4,693. , 958, and 5,512, 418, can be synthesized using a conventionally known chemical reaction. 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, sulfonate esters or halides) results in the polymer main chain or side chain. A method of introducing an organic onium group is also mentioned.

  The phenyl group substituted with a vinyl group in the polymer A is a group that can contribute to a photopolymerization reaction or a photocrosslinking reaction by the action of a photopolymerization initiator or a photoacid generator. 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 into which a phenyl group substituted with a vinyl group is introduced 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 each is a hydrogen atom, a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group. A group selected from a group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, 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, 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, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, 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 an integer of 0 or 1, and q ₁ represents an integer of ₁ to 4.

In the formula, L ₁ represents a polyvalent linking group consisting of an atom selected from a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom, or an atomic group selected from a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom. To express. 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, mark doll 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, Examples thereof include nitrogen-containing heterocycles such as quinoline ring and quinoxaline ring, furan ring, and thiophene ring, and 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, JP-B-49-34041, JP-A-6-105353, JP-A-2000-181062, and JP-A-2000-187322. Any method as shown in a publication or 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 precursor of the polymer A include allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, 2-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) ) Amino group-containing monomers such as amines and quaternary ammonium salts thereof, nitrogen-containing heterocycle-containing monomers such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole and N-vinylcarbazole, and quaternary ammonium salts thereof , ( -Vinylbenzyl) Quaternary phosphonium salt monomers such as trimethylphosphonium bromide, Tertiary sulfonium salt monomers such as dimethyl-2-methacryloyloxyethylsulfonium methosulfate, 2-chloromethylstyrene, 4-chloromethylstyrene, 4-bromomethyl Examples include, but are not limited to, halogenated alkyl group-containing monomers such as styrene, 2-chloroethyl acrylate, and 2-chloroethyl methacrylate.

  Further, 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 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, dodecyl methacrylate, aryl (meth) acrylates such as phenyl methacrylate, benzyl methacrylate, or arylalkyl (meth) acrylate , Acrylonitrile, methacrylonitrile, phenylmaleimide, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate and other vinyl esters, methyl vinyl ether, vinyl ether such as butyl vinyl ether, and others, acryloyl Examples include various monomers such as morpholine, 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.

  The polymer A of the present invention is particularly preferably a case where a phenyl group substituted with a vinyl group is bonded to the main chain via a cationic group. 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 vinyl groups contained in the polymer were substituted in order to improve sensitivity. Since the solubility in water does not decrease even if the proportion of the phenyl group is increased, both sensitivity and water developability can be satisfied at the same time. The unit structure of the polymer in the case where the phenyl group substituted with the vinyl group as described above is bonded to the master through a cationic group can be specifically represented by the following general formula (II).

In the formula, A ₁ ⁺ represents an organic onium group selected from organic onium groups 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, a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group, a benzyl group, etc.) or an aryl group (for example, 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, 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 (II), 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 (II). 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 polyvalent 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 (II). 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, a vinyl group is substituted in addition to a polymer having a repeating unit in which a phenyl group substituted with a vinyl group as described above is bonded to a principal group through a cationic group. A polymer having a repeating unit in which a phenyl group is bonded to the main chain directly or via a linking group containing no cationic group and a repeating unit having a cationic group can also be used.

  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 must be in the range of 10% by mass to 80% by mass of the total polymer composition. Is particularly preferred.

  In the case of a polymer comprising a repeating unit in which a phenyl group substituted by a vinyl group is bonded to the main chain directly or via a linking group not containing a cationic group and a repeating unit having a cationic group, a vinyl group In the case of a repeating unit having a substituted phenyl group, 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. If the repeating unit having a cationic group is not 30% by mass or more, sufficient water solubility may not be obtained, and if it is not 90% by mass or less, sufficient image formation may not be possible.

  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 phenyl group substituted with a vinyl group in the side chain and having a sulfonic acid group will be described in detail.

  The polymer B of the present invention is a polymer in which a phenyl group substituted with a vinyl group and a sulfonic acid 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 phenyl group and the sulfonic acid group substituted with the vinyl group may be independently bonded to the main chain, or the phenyl group substituted with the vinyl group and the sulfonic acid group share part or all of the linking group. You may combine in the form to do.

  In the phenyl group substituted by the vinyl group, the phenyl group may be substituted, and the vinyl group is a halogen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, It may be substituted with an alkyl group, aryl group, alkoxy group, aryloxy group or the like.

  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 R _{4 in} 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 formula (I). m ₃ represents an integer of 0 to 4, p ₃ represents an integer of 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. . The linking group L ₄ preferably contains 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 are included. 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 a repeating unit having a phenyl group substituted with a vinyl group in the side chain and a repeating unit having a sulfonic acid group, or the effect of the present invention. As long as the above is not hindered, a polymer in which another repeating unit is further introduced may be used. Further, 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 for 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 photosensitive layer 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 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 “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” J.P.FOUASSIER, J.F.RABEK (1993), P.A. Compounds having a benzophenone skeleton or thioxanthone skeleton described in 77 to 177, α-thiobenzophenone compounds described in Japanese Patent Publication No. 47-6416, benzoin ether compounds described in Japanese Patent Publication No. 47-3981, and Japanese Patent Publication No. 47- An α-substituted benzoin compound described in Japanese Patent No. 22326, a benzoin derivative described in Japanese Patent Publication No. 47-23664, an aroylphosphonic acid ester described in Japanese Patent Publication No. 57-30704, and Japanese Patent Publication No. 60-26483. Dialkoxybenzophenones described in JP-B-60-26403, benzoin ethers described in JP-A-62-81345, p-di (dimethylaminobenzoyl) benzene described in JP-A-2-211452, A thio-substituted fragrance described in JP-A-61-194062 Group ketones, acylphosphine sulfides described in JP-B-2-9597, acylphosphines described in JP-B-2-9596, thioxanthones described in JP-B-63-61950, JP-B-59-42864 Mention may be made of the coumarins described in the publication.

(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 Nos. 52-14277, 52-14278, 52-14279, and the like.

(C) Examples of the organic peroxide include almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. For example, 3,3 ′, 4,4′-tetra- (tert -Butylperoxycarbonyl) 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, 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'- Traphenylbiimidazole, 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.

(F) Examples of azinium salt compounds include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, JP-B-46-42363. The compound group which has NO bond as described in gazettes 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 things.

(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 the 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 No. 3,987,037, No. 4,189,323, JP-A Nos. 61-151644, 63-298339, No. 4-69661, Trihalomethyl-s-triazine compounds described in JP-A-11-153589, etc., JP-A-54-74728, JP-A-55-77742, JP-A-60-138539, JP-A-61-143748 2-trihalomethyl-1,3,4-oxadiazole derivatives described in JP-A-4-362644, JP-A-11-84649, etc. And the like. 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, and JP-A-9-188710. Organoboron ammonium compounds and organoboron sulfonium compounds and organoboron oxosulfonium compounds described in JP-A-6-175561, JP-A-6-175564, JP-A-6-157623, etc. JP-A-6-175553, JP-A-6-175554, etc., organoboron iodonium compounds, JP-A-9-188710, etc., organoboron phosphonium compounds, JP-A-6-348011, JP-A-7- No. 128785, No. 7-140589, No. 7-292014, No. 7- And organic boron transition metal coordination complex compound described in 06527 JP, 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, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group or a heterocyclic group. To express. Of these, it is particularly preferred that one of R 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 compound and an organic boron anion is used, 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 compounds 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.

  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.

  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. it can. Examples of photoacid generators that can be used in the present invention include (k) aromatic diazonium salt compounds, (l) p-valic acid-o-nitrobenzyl ester, benzenesulfonic acid-o-nitrobenzyl ester, o- 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, Described in JP-A-11-322707, 2000-1469, etc. Sulfonyl diazomethane compounds and the like can be exemplified.

  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 a phenyl group substituted with two or more vinyl 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 and the like. .

  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 by being mounted on a printing machine without performing a development process, and a processless having excellent printing durability. A lithographic printing plate can be obtained.

  The photosensitive layer of the processless lithographic printing plate of the present invention can be sensitive to light of various wavelengths by containing a dye in 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, And coumarin, ketocoumarin, quinacridone, indigo, styryl, squarylium compound, pyrylium compound, and further, European Patent No. 0,568,993, US Patent No. 4,508,811, No. 5,227, The compounds described in No. 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 layer, and further in the range of 5 to 200 mg per square meter of the photosensitive layer. This is particularly preferred.

  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 the photosensitive layer of the processless lithographic printing plate contains, a colorant can also 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 parts by mass to 0.5 parts by mass with respect to 1 part by mass of the polymer.

  The photosensitive layer of the processless lithographic printing plate can be added with other elements in addition to the above elements for various purposes. 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.

  The photosensitive layer of the processless lithographic printing plate of the present invention is produced by applying a coating liquid of a photosensitive composition comprising the above-described elements onto a support and drying. 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 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.

Synthesis example 1
Example of synthesis of hydrophilic polymer (WP-1) In a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube, 80 g of acrylamide and 20 g of acrylic acid were weighed, 100 g of ethanol and pure water 450 g was added and dissolved. On a water bath adjusted to 60 ° C., 0.4 g of 2,2′-azobis (2-amidinopropane) dihydrochloride as a polymerization initiator was added to initiate polymerization. Since the temperature of the system increased after the start of polymerization, cold water was added to keep the internal temperature at 70 ° C., and stirring was continued at this temperature for 4 hours. The obtained copolymer solution was used for evaluation without purification.

  A coating solution for a backing layer having the following composition was prepared. Then, the coating solution was applied to a polyethylene terephthalate film support having a thickness of 0.10 mm and having a gelatin undercoat layer, and dried for 30 m so as to have a dry thickness of 3.0 μm. This was put into a thermostat kept at 50 ° C. for 2 days to be crosslinked.

<Backcoat layer coating solution 1>
Gelatin 40.0 parts by mass Denacol EX614 4.0 parts by mass (manufactured by Nagase ChemteX Corporation; epoxy compound)
Aron-T50 0.1 parts by mass metal oxide A (described in Table 1) 30.0 parts by mass carbon black (Aqua-Black 162 (average particle size 100 nm): manufactured by Tokai Carbon Co., Ltd.)
It was adjusted to 100 parts by mass with 3.0 parts by mass of water.

  Thereafter, a hydrophilic layer coating solution having the following composition was prepared on the opposite surface of the polyethylene terephthalate film coated with the backing layer, and coated and dried to a dry thickness of 1.5 μm. This was placed in a thermostat kept at 50 ° C. for 2 days to crosslink.

<Coating solution>
Hydrophilic polymer (WP-1) 3.1 parts by mass Denacol EX811 0.47 parts by mass (manufactured by Nagase ChemteX Corporation; epoxy compound)
PS-M 6.2 parts by mass (Nissan Chemical Co., Ltd .; colloidal silica)
Ethanol 10.0 parts by mass Water was adjusted to 100 parts by mass.

A coating solution of a photosensitive composition having the following composition was prepared, and then the coating solution was dried on the hydrophilic layer at a dry film thickness of 1 μm and 70 ° C. for 2 minutes to prepare a sample.
<Coating liquid A>
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 sample was wound around a paper core having an outer diameter of 80 mm for 30 m, the end was taped and placed in a black plastic bag, and allowed to stand for 1 week in an environment of 35 ° C. and relative humidity of 80%. Thereafter, the tape was removed from the bag, and the blocking between the photosensitive layer and the backing layer was evaluated according to the following criteria. ○: The photosensitive layer and the backing layer do not adhere at all. ○: The edge portion of the film is slightly adhered. (Triangle | delta): The photosensitive layer and the backing layer have adhere | attached in a part of film inside. Δ ×: Most of the film is adhered. X: The photosensitive layer and the backing layer are adhered so that the film is not peeled off. The results are shown in Table 1.

In addition, a part of the above sample is not left in an environment of 35 ° C. and a relative humidity of 80%, but is wound around a photosensitive drum in which a groove having a depth of 0.1 mm and a width of 10 mm is dug, and the wavelength is 830 nm. After exposing a 2400 dpi, 175 line 50% flat mesh and 80% flat mesh with an exposure energy of 120 mJ / cm ² with a laser beam with a diameter of 20 μm, soak it in water at 25 ° C. for 15 seconds and use a cellulose sponge. The photosensitive layer was rubbed to develop and dried.

  The halftone dot area ratio of the portion of the sample exposed to 50% flat screen was measured. Further, the exposed portion of the 80% flat mesh was visually observed, and whether or not the drum groove pattern appeared on the flat mesh was visually evaluated according to the following criteria. ○: No groove pattern is seen in the image area. Δ: Drum groove pattern is seen thinly. X: Drum groove pattern is clearly seen. The results are shown in Table 1.

  As can be seen from Table 1, the sample of the comparative example caused blocking under high humidity conditions, whereas the sample of the present invention did not. Moreover, the addition of carbon black could prevent the influence of the groove of the drum.

  Samples were prepared under the same conditions as in Example 1 except that the polymer used in the photosensitive layer of Example 1 was changed to polymer B (SP-1), and evaluation was performed based on the same criteria as in Example 1. Similar results were obtained.

Claims (1)

  Water-soluble polymer containing a hydrophilic layer on a plastic film support and a cationic water-soluble polymer having a phenyl group substituted with a vinyl group on the side chain or a phenyl group substituted with a vinyl group on the side chain and a sulfonic acid group And a photosensitive layer containing at least a photopolymerization initiator or a photoacid generator in this order, and containing a metal oxide and carbon black on the surface of the plastic film support opposite to the side having the photosensitive layer. Processless photosensitive lithographic printing plate with a backing layer.