JP2012189781A - Processing method of photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of a photosensitive lithographic printing plate in which excellent printing contamination resistance can be obtained if liquid exchange is not performed for a long period.SOLUTION: Provided is a processing method of a photosensitive lithographic printing plate that includes a photopolymerizable photosensitive layer on a substrate and includes an oxygen intercepting layer on a side further away from the substrate than the photopolymerizable photosensitive layer, in which the photosensitive lithographic printing plate is processed with a process liquid containing polyvinyl alcohol decomposing bacteria.

Description

  The present invention relates to a method for processing a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support and sequentially having an oxygen blocking layer on the side farther from the support than the photopolymerizable photosensitive layer.

  In recent years, computer-to-plate (CTP) technology that directly outputs digital data formatted on a computer screen to a lithographic printing plate has been developed along with the digitization of the plate making system, and various plates equipped with various lasers as output machines. The development of setters and photosensitive lithographic printing plates compatible with these is being actively pursued. As such an output machine, an output machine using various lasers such as a blue-violet semiconductor laser (violet laser), a helium neon laser, a red LED, a near infrared laser, an infrared laser, and an argon laser is preferably used.

  As a lithographic printing plate having a photopolymerizable photosensitive layer corresponding to such various lasers, for example, JP-A-9-134007 discloses a radically polymerizable compound having an ethylenically unsaturated bond, a photosensitizing dye, A lithographic printing plate containing a polymerization initiator is disclosed, and JP-A-5-5988, JP-A-5-194619, JP-A-2000-98603, and the like disclose combinations of an organic boron anion and a dye. JP-A-4-31863, JP-A-6-43333, etc. disclose a combination of a dye and an s-triazine compound, and JP-A-7-20629 and JP-A-6-36633. JP-A-7-271029 discloses a combination of a resole resin, a novolac resin, an infrared absorber and a photoacid generator. No. 2 and JP-A No. 11-231535 disclose a combination of a specific polymer, a photoacid generator and a near-infrared sensitizing dye, and JP-A No. 2001-290271 discloses a side chain. A photosensitive lithographic printing plate using a polymer having a phenyl group substituted with a vinyl group is disclosed. JP-A-2005-274695 and 2007-25220 disclose a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer corresponding to a violet laser light source.

  Furthermore, Japanese Unexamined Patent Application Publication No. 2003-215801 (Patent Document 1) discloses a photosensitive lithographic printing plate which is highly sensitive and can be developed with water. A cation in which a vinyl group is bonded to a side chain on a support via a phenyl group. A photosensitive lithographic printing plate having a photosensitive layer containing a water-soluble or anionic water-soluble polymer, a photopolymerization initiator or an acid generator is disclosed. Further, as a hydrophilic layer preferably used when a plastic film support is used as a support, a hydrophilic resin layer made of a (meth) acrylate polymer having a hydroxyalkyl group described in JP-B-49-2286, A hydrophilic layer composed of a urea resin and a pigment described in JP-A-56-2938, a hydrophilic layer obtained by curing an acrylamide polymer described in JP-A-48-83902 with aldehydes, A hydrophilic layer obtained by curing a composition containing a water-soluble melamine resin, polyvinyl alcohol, and a water-insoluble inorganic powder described in JP-A-62-280766, and an amidino in a side chain described in JP-A-8-184967. Hydrophilic layer obtained by curing a water-soluble polymer containing a repeating unit having a group, JP-A-8-272087 A hydrophilic layer containing a hydrophilic (co) polymer described in the publication and cured with hydrolyzed tetraalkylorthosilicate, a hydrophilic layer having an onium group described in JP-A-10-296895, A hydrophilic layer obtained by three-dimensionally cross-linking a cross-linked hydrophilic polymer having a Lewis base described in Kaihei 11-311861 by interaction with a polyvalent metal ion, and a hydrophilic layer described in JP-A No. 2000-122269 A hydrophilic layer containing a water-soluble resin and a water-dispersible filler is described.

  A lithographic printing plate having such a photopolymerizable photosensitive layer needs to have sufficient sensitivity in order to obtain an image having sufficient strength by exposure in a short time with a laser. In the photocrosslinking reaction utilizing radical polymerization, an oxygen blocking layer is usually provided on the side farther from the support than the photosensitive layer in order to prevent the generated radicals from being deactivated by oxygen and as a result the sensitivity is lowered. Things are known.

  In the case of a photosensitive lithographic printing plate having an alkali-eluting photosensitive layer, the oxygen blocking layer needs to be dissolved and removed with water before the photosensitive layer in the non-image area is eluted with an alkali developer after exposure. When processing with an automatic developing machine, a step of removing the oxygen blocking layer is provided as a pre-water washing tank before the developing tank. This is described in, for example, Japanese Patent Application Laid-Open No. 2003-84450 (Patent Document 2). Even in the development processing at a pH of 10 or less, pre-washing may be provided as necessary. This is described in, for example, JP 2010-32611 A (Patent Document 3). Furthermore, the photosensitive lithographic printing plate of Patent Document 1 described above can be developed with water (no need to remove the oxygen barrier layer before development), and therefore, the development process is performed without a pre-water washing tank.

  However, in any of the processing methods, when the photosensitive lithographic printing plate is processed for a long period of time, the photosensitive lithographic printing plate produced by plate making causes printing stains due to the removed oxygen blocking layer. There was a need for improvement. Further, in order to improve this dirt, it is necessary to frequently change the liquid, and improvement has been demanded. In particular, the non-image portion of the photosensitive lithographic printing plate having a hydrophilic layer on the plastic support described above is more hydrophilic than the non-image portion of the photosensitive lithographic printing plate having a roughened and anodized aluminum support. Therefore, the above-mentioned stains are particularly likely to occur, and improvement has been demanded.

JP 2003-215801 A JP 2003-84450 A JP 2010-32611 A

  An object of the present invention is a processing method of a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support, and having an oxygen blocking layer on the side farther from the support than the photopolymerizable photosensitive layer. Thus, it is an object of the present invention to provide a method for processing a photosensitive lithographic printing plate that can provide good printing stain resistance even when liquid replacement is not performed for a long period of time.

The above object has been achieved by the following invention.
A method for processing a photosensitive lithographic printing plate comprising a photopolymerizable photosensitive layer on a support, and having an oxygen blocking layer on a side farther from the support than the photopolymerizable photosensitive layer, A method for treating a photosensitive lithographic printing plate, comprising treating the lithographic printing plate with a treatment liquid containing a polyvinyl alcohol-degrading bacterium.

  According to the present invention, it is possible to provide a method for processing a photosensitive lithographic printing plate that can provide good printing stain resistance even when liquid replacement is not performed for a long time.

  The polyvinyl alcohol-degrading bacterium used in the processing method of the photosensitive lithographic printing plate of the present invention is described in, for example, a bacterium belonging to the genus Pseudomonas used for obtaining an enzyme described in Japanese Patent Publication No. 3499848, or JP-A-7-108297. Bacterium belonging to the genus Corynebacterium, Rhodococcus genus, Caseobacter genus, the bacterium belonging to the genus Sphingomonas aromatisivolans described in JP 2005-27839 A, and the comamonas One or a combination of bacteria belonging to the genus Testosteroni, such as those belonging to the genus Microbacterium levaniformans described in JP-A-2006-42612, can be used. Among them, bacteria belonging to the genus Pseudomonas used for obtaining the enzyme described in Japanese Patent Publication No. 3499848 are preferably used.

  The polyvinyl alcohol-degrading bacterium described above in the processing method of the photosensitive lithographic printing plate of the present invention is used for the step of removing the oxygen barrier layer of the automatic processor used for the plate making process, and is an automatic processor having a pre-cleaning tank. In such a case, the bacterium is added to the treatment liquid put into the pre-cleaning tank. In addition, in the case of processing with a chemical-less developer and pre-washing is not performed, the above-mentioned bacteria can be added to the processing solution put into the developing tank.

  As a method of adding polyvinyl alcohol-degrading bacteria to these treatment liquids, polyvinyl alcohol-degrading bacteria may be added directly to the treatment liquid, or through a filter in which polyvinyl alcohol-degrading bacteria are adsorbed on diatomaceous earth, pumice or activated carbon. It may be circulated and added to the treatment liquid.

When the bacterium of the present invention is introduced into a pre-water washing tank or a developing tank, the number of bacteria is preferably 10 ⁷ to 10 ¹¹ cfu / ml, more preferably 10 ⁸ to 10 ⁹ cfu / ml. The number of fungi is determined by applying 0.1 ml each of a 10-fold diluted solution to an agar medium and culturing to give a dilution ratio when the number of colonies generated is 50 to 500, and colonies generated at that time. Can be obtained by visual counting (colony counting method). In addition, an approximate number of bacteria can be obtained by using a calibration curve of turbidity measured with light of 600 nm wavelength using a turbidimeter and the number of bacteria obtained by the colony counting method.

  When the treatment is performed with the treatment liquid of the present invention to which polyvinyl alcohol-degrading bacteria are added, it is preferable that oxygen be constantly taken into the treatment liquid. Therefore, air is blown into the processing liquid with an air pump, or the processing liquid is always circulated, and preferably the circulated processing liquid is circulated by returning it from the upper part of the processing tank to the processing tank using a shower type. It is preferable to make the liquid come into contact with air as much as possible.

  The photosensitive lithographic printing plate used in the processing method of the present invention has an oxygen barrier layer on the side farther from the support than the photosensitive layer. As the layer structure of this photosensitive lithographic printing plate, for example, a photopolymerizable photosensitive layer is provided on a roughened and anodized aluminum support, and an oxygen blocking layer is provided on the photopolymerizable photosensitive layer. Alternatively, a hydrophilic layer, a hydrophilic auxiliary layer, and a photopolymerizable photosensitive layer are provided in this order on a plastic film support, and an oxygen blocking layer is provided on the photopolymerizable photosensitivity. Moreover, you may provide a back layer in the back side (opposite surface of a photopolymerizable photosensitive layer surface) of a plastic film support body.

[Support]
As the support for the photosensitive lithographic printing plate used in the processing method of the present invention, an aluminum support can also be used. In this case, the surface of the aluminum support is roughened by mechanical or electrolysis after degreasing the surface of the aluminum plate, for example, as described in JP-A-8-244371 and JP-A-10-129142. By performing chemical treatment on the surface such as anodization, sufficient adhesion to the image area and sufficient water retention of the non-image area can be obtained.

  Moreover, various plastic films are mentioned as a support body of the photosensitive lithographic printing plate used for the processing method of this invention. Plastic film supports include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyvinyl acetal, polycarbonate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose nitrate, and polyethylene resin on both sides of the paper. Typical examples include coated resin-coated paper, and polyethylene terephthalate and polyethylene naphthalate are particularly preferably used. These plastic films are preferably subjected to a hydrophilic treatment on the surface, and examples of the hydrophilic treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment.

[Hydrophilic layer]
In the photosensitive lithographic printing plate used in the processing method of the present invention, it is preferable to provide a hydrophilic layer on the plastic film support. The hydrophilic layer contains a water-soluble resin and inorganic fine particles. Examples of the inorganic fine particles include colloidal silica, titanium dioxide particles, alumina particles (for example, aluminum oxide hydrate, aluminum hydroxide), zeolite, and other metals. Examples thereof include particles made of an oxide, and colloidal silica and titanium dioxide particles are preferably used. These inorganic fine particles may be subjected to a surface treatment on the particle surface. The content of these inorganic fine particles in the hydrophilic layer is preferably 50% by mass or more, more preferably 55% by mass or more based on the total mass of the hydrophilic layer.

  Colloidal silica that is preferably used in combination with the hydrophilic layer is a necklace formed by a series of spherical, needle-shaped, amorphous, or spherical particles having an average particle size of preferably 5 to 200 nm measured by a light scattering particle size distribution analyzer. Silica sols having various shapes such as shapes and particle diameters and stably dispersed in water are preferably used. As such materials, various colloidal silicas are provided, for example, under the name of Snowtex from Nissan Chemical Industries, Ltd., and as a spherical silica sol, Snowtex XS (particle diameter 4 to 6 nm), Snowtex S (particle diameter 8) To 11 nm), Snowtex 20 (particle size 10 to 20 nm), Snowtex XL (particle size 40 to 60 nm), Snowtex YL (particle size 50 to 80 nm), Snowtex ZL (particle size 70 to 100 nm), Snowtex As an acidic type silica sol from which MP-2040 (particle diameter: 200 nm) and sodium salt on the surface have been removed, Snowtex OXS, OS and the like can be preferably used. Examples of the needle-like or amorphous silica sol include Snowtex UP, OUP, and Fine Cataloid F-120 available from Catalyst Kasei Kogyo Co., Ltd. Examples of the necklace-shaped silica sol include Snowtex PS-S (particle diameter 80 to 120 nm), PS-M (particle diameter 80 to 150 nm), and PS-SO and PS-MO which are acidic types thereof. Furthermore, Snowtex C (particle diameter: 10 to 20 nm) whose surface is modified with alumina can also be used.

  Titanium dioxide particles preferably used in combination with colloidal silica are preferably spherical particles having an average particle diameter of 10 to 800 nm, and their production methods include chlorine method and sulfuric acid method, such as anatase type, rutile type, bulcalite type, etc. However, preferably, rutile type titanium dioxide is surface-treated with an inorganic substance. Examples of the inorganic treatment on the surface of titanium dioxide include alumina treatment, silica treatment, zirconia treatment, zinc treatment, tin treatment, and antimony treatment, and each oxide is used. Among these, silica treatment, zirconia treatment, and zinc treatment are preferable, and silica treatment and zirconia treatment are particularly preferable. These inorganic treatments may be composite treatments, and examples include composite treatment of silica and alumina, composite treatment of zirconia and alumina, and composite treatment of silica, zirconia and alumina. Such titanium dioxide particles are, for example, from Sakai Chemical Industry Co., Ltd. R-11P (particle diameter 200 nm), R-21 (particle diameter 200 nm), R-61N (particle diameter 260 nm), SR-1 (particle diameter 250 nm). ), R-5N (particle size 250 nm), R-45M (particle size 290 nm), A-110 (particle size 150 nm), A-190 (particle size 150 nm), Ishihara Sangyo Co., Ltd. TTO-55A (particle size) 30 to 50 nm) and TTO-55D (particle diameter 30 to 50 nm). In addition to the above combinations, several kinds of inorganic fine particles used in these hydrophilic layers can be used in combination.

  Examples of the water-soluble resin contained in the hydrophilic layer of the photosensitive lithographic printing plate used in the processing method of the present invention include polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, and gelatin. A polymer represented by the following general formula (1) is preferably used since a photosensitive lithographic printing plate having excellent soiling properties can be obtained.

  In the formula, X represents mass% of repeating units in the polymer composition, and represents an arbitrary numerical value from 1 to 40. The repeating unit A represents a repeating unit having a group selected from a carboxy group, an amino group, a hydroxyl group and an acetoacetoxy group as a reactive group, and the repeating unit B is a repeating unit having a hydrophilic group necessary for making the polymer water-soluble. Represents a unit.

  It is important that the water-soluble polymer represented by the general formula (1) contains a reactive group in the molecule for allowing a crosslinking reaction to proceed efficiently with a crosslinking agent described later. Examples of such reactive groups include a carboxy group, an amino group, a hydroxyl group, and an acetoacetoxy group. In order to obtain a water-soluble polymer having such a reactive group in the molecule, it is preferable to incorporate various monomers having a reactive group in a copolymerized form. As the monomer corresponding to the repeating unit A represented by the general formula (1), acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, cinnamic acid Carboxy group-containing monomers such as maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene, acrylamide-N-glycolic acid and their salts, allylamine, diallylamine, 2-dimethylaminoethyl acrylate, 2-dimethylamino Ethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, 3-dimethylaminopropyl acrylamide, 3-dimethylaminopropyl methacrylamide, 4-aminostyrene Amino group-containing monomers such as 4-aminomethylstyrene, N, N-dimethyl-N- (4-vinylbenzyl) amine, N, N-diethyl-N- (4-vinylbenzyl) amine, 4-vinylpyridine, 2 Nitrogen-containing heterocycle-containing monomers such as vinylpyridine and N-vinylimidazole, (meth) acrylamides such as N-methylolacrylamide and 4-hydroxyphenylacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy Examples thereof include hydroxyalkyl (meth) acrylates such as propyl acrylate, 2-hydroxypropyl methacrylate, and glycerol monomethacrylate, and acetoacetoxy methacrylate, but are not limited to these examples.

  In the above general formula (1), X, which is the proportion of the repeating unit A in the copolymer, is 1 to 40, and if it is less than this range, sufficient film strength cannot be obtained even if the crosslinking reaction proceeds. In some cases, if the amount is larger than this range, the effect of introducing the repeating unit B for imparting water solubility described below is reduced, and the affinity of the hydrophilic layer for water may be reduced.

  Furthermore, as a monomer for giving the repeating unit B in the general formula (1), vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, 2- Sulfonic acid group-containing monomers such as acrylamido-2-methylpropanesulfonic acid and their salts, Phosphoric acid group-containing monomers such as vinylphosphonic acid and their salts, dimethyl diallyl ammonium chloride, acrylic acid-2- (trimethylammonio) Ethyl ester, methacrylic acid-2- (trimethylammonio) ethyl ester, acrylic acid-2- (triethylammonio) ethyl ester, methacrylic acid-2- (triethylammonio) ethyl ester, (3-acrylamidopropyl) trime Quaternary ammonium salts such as ruammonium chloride, N, N, N-trimethyl-N- (4-vinylbenzyl) ammonium chloride, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N (Meth) acrylamides such as N, diethylacrylamide, N-isopropylmethacrylamide, methacrylic acid methoxydiethylene glycol monoester, methacrylic acid methoxypolyethylene glycol monoester, methacrylic acid polypropylene glycol monoester , N-vinyl pyrrolidone, N-vinyl caprolactam and the like, but are not limited thereto. These water-soluble monomers may be used alone to constitute the repeating unit B, or any two or more of them may be used. Specific examples of preferred water-soluble polymers in the photosensitive lithographic printing plate used in the processing method of the present invention are shown below. In the present invention, water-soluble means that 0.5 g or more of a water-soluble polymer is dissolved in 1 L of water. Specific examples of the water-soluble polymer represented by the general formula (1) are shown below.

  A crosslinking agent for crosslinking a water-soluble resin is preferably used in the hydrophilic layer of the photosensitive lithographic printing plate used in the processing method of the present invention. Examples of the crosslinking agent include various known compounds. Specific examples include epoxy compounds, aziridine compounds, oxazoline compounds, isocyanate compounds and derivatives thereof, aldehyde compounds such as formalin, methylol compounds, hydrazide compounds, and the like. Particularly preferred crosslinking agents include epoxy compounds, aldehyde compounds, and methylol. A compound.

  As the epoxy compound, a compound having two or more epoxy groups in the molecule is preferably used. Specific examples of preferred epoxy compounds are shown below.

  Specific examples of preferable compounds as the aziridine compound are shown below.

  As the oxazoline compound, a compound containing two or more groups represented by the following general formula (2) in the molecule as a substituent is preferable, and various commercially available compounds are provided, for example, by Nippon Shokubai Co., Ltd. under the trade name Epocross. Various grades of compounds are preferably used.

  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 self-emulsifying isocyanate compounds include Japanese Patent Publication No. 55-7472 (US Pat. No. 3,996,154) and Japanese Patent Laid-Open No. 5-222150 (US 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.

  Examples of aldehyde compounds and methylol compounds such as formaldehyde and glyoxal include formaldehyde, glyoxal, and various N-methylol compounds as shown below.

  Specific examples of compounds that can be preferably used as the hydrazide compound are shown below.

  There is a preferred range for the ratio of the various crosslinking agents and water-soluble resins 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 water-soluble resin.

  Furthermore, the hydrophilic layer of the photosensitive lithographic printing plate preferably contains an acrylic polyol resin. This improves stain resistance and printing durability. The aspect in which the acrylic polyol resin used in the present invention is contained as an aqueous dispersion is preferable.

  Examples of the acrylic polyol resin used in the present invention include those obtained by copolymerizing an acrylic monomer having a hydroxyl group and an acrylic monomer having no hydroxyl group, and having two or more hydroxyl groups in one molecule. Examples of such an acrylic polyol resin include water-based acrylic polyols manufactured by Shinto Paint Co., Ltd., acrylic polyols manufactured by DIC Corporation (WE-301, WE-306), and bihydrs manufactured by Sumika Bayer Urethane Co., Ltd. (VPLS2058, VPLS2235, XP2470). Etc. are commercially available, and these can be obtained and used.

  The acrylic polyol resin is preferably used in the range of 0.1 to 0.5 parts by mass with respect to 100 parts by mass of the water-soluble resin described above.

  There is a preferred range for the dry weight of the hydrophilic layer, specifically, the dry weight of the hydrophilic layer is between 0.6 g and 10 g per square meter, and the preferred range is between 2 g and 6 g per square meter. It is.

  The hydrophilic layer of the photosensitive lithographic printing plate used in the processing method of the present invention can contain a surfactant, a pH adjuster and the like in addition to the water-soluble resin, the inorganic fine particles, and the hardener.

[Photopolymerizable photosensitive layer]
The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate used in the processing method of the present invention specifically includes a polymer containing a monomer having a polymerizable double bond as a copolymerization component and a photopolymerization initiator. It is a photosensitive layer. Examples of the monomer having a polymerizable double bond include allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β-phenyl vinyl acrylate, vinyl methacrylamide, vinyl. Examples include acrylamide, α-chlorovinyl methacrylate, α-chlorovinyl acrylate, β-methoxyvinyl methacrylate, β-methoxyvinyl acrylate, vinyl thioacrylate, vinyl thiomethacrylate, and the like.

  As a preferable embodiment of the above polymer, a monomer having a polymerizable double bond and a water-soluble group-containing monomer (for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4- There is a copolymer having a polymerizable double bond and a water-soluble group in a side chain containing carboxystyrene, 4-sulfostyrene, acrylonitrile, etc.) as a copolymerization component. By including a water-soluble group in the polymer structure, the developability of the photopolymerizable photosensitive layer in the unexposed area is promoted.

  As a more preferable embodiment of the above-described copolymer, a copolymer having a monomer having a phenyl group substituted with a vinyl group as a monomer having a polymerizable double bond can be mentioned. The phenyl group substituted with a vinyl group is a vinyl group substituted with an aromatic ring such as a benzene ring or a naphthalene ring, and the vinyl group is a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group. , An amino group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group and the like, and the aromatic ring may have a substituent. By incorporating a copolymer with a water-soluble group and a phenyl group with a vinyl group substituted in the side chain in the polymer structure into the photopolymerizable photosensitive layer, the recombination of styryl radicals generated by the generated radicals increases the recombination. A sensitive photosensitive lithographic printing plate is obtained. The phenyl group substituted with a vinyl group is specifically represented by the following general formula (3).

In the formula, R ₁₁ , R ₁₂ and R ₁₃ may be the same or different and are each a hydrogen atom, halogen atom, carboxy group, sulfo group, nitro group, cyano group, amide group, amino group, 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, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkenyl group, a hydroxy group, and an alkoxy group. , Aryloxy group, alkylthio group, arylthio group, alkyl It may be substituted with an amino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group or the like. Among these groups, those in which R ₁₁ 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 ₁₂ and R ₁₃ are hydrogen atoms are particularly preferable.

In the formula, R ₁₄ represents a hydrogen atom, a halogen atom, a carboxy group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, 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 carboxy 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, an alkynyl group, and a hydroxy 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, an arylsulfonyl group and the like.

In the formula, m ₁ represents an integer of 0 to 4, and p ₁ represents an integer of 0 or 1. 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 comprising a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom group.

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 carboxy 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.

  As the most preferred embodiment of the copolymer, a monomer having a phenyl group substituted with a vinyl group as a monomer having a polymerizable double bond, and a monomer having a carboxy group in the structure as a water-soluble group-containing monomer (for example, acrylic acid, methacrylic acid) Acid, 4-carboxystyrene, carboxyethyl acrylate, etc.) as a copolymerization component, and a copolymer having a phenyl group substituted with a vinyl group in the side chain and a carboxy group (hereinafter referred to as a carboxylic acid type polymer). . In this carboxylic acid type polymer, the carboxy group in the structure forms a salt with an alkaline substance (for example, sodium hydroxide, sodium carbonate, triethylamine, etc.) contained in the developer during the development processing, and the photopolymerizable polymer in the unexposed area. Development of the photosensitive layer is performed. Therefore, when a carboxylic acid type polymer is used, a method using an alkaline developer described later in the development process (hereinafter referred to as alkali development) is preferable, and the pH value of the alkaline developer is 10.0 or more.

  Specific examples of the carboxylic acid type polymer in the photosensitive lithographic printing plate used in the processing method of the present invention are shown below.

  As the most preferred embodiment of the copolymer, a monomer having a phenyl group substituted with a vinyl group as a monomer having a polymerizable double bond and a monomer having a sulfonic acid group in the structure as a water-soluble group-containing monomer (for example, 3-sulfopropyl methacrylate, 4-sulfostyrene, 4-sulfo-n-butylmethacrylamide, sulfo-tert-butylacrylamide, etc.) as a copolymerization component, and a phenyl group and a sulfonic acid group in which a vinyl group is substituted on the side chain (Hereinafter referred to as sulfonic acid type polymer), and the sulfonic acid group forms a salt (for example, sodium salt, potassium salt, triethylammonium salt, lithium salt, tetramethylammonium salt, etc.). May be. In this sulfonic acid type polymer, since the sulfonic acid group in the structure enhances water solubility, the above-mentioned alkaline developer may be used, but in a more preferred embodiment of the photosensitive lithographic printing plate used in the processing method of the present invention. It is possible to use a method (hereinafter referred to as chemicalless development) using a chemicalless developer in which the pH value of a certain developer is in the range of 4.0 or more and less than 10.0. However, the oleophilicity of the image formed by the sulfonic acid type polymer is relatively low, and when the ink feed amount is increased by the printing machine so as to obtain a sufficient image density at the time of printing, the non-image portion is particularly easily stained. . Therefore, in such a system, it is required to impart high water retention to the hydrophilic layer, and the photosensitive lithographic printing plate used in the processing method of the present invention can be used particularly suitably in such a system. In addition, the sulfonic acid type polymer, like the carboxylic acid type polymer described above, has a phenyl group having a vinyl group substituted on the side chain, so that high sensitivity can be achieved.

  Specific examples of the sulfonic acid type polymer in the photosensitive lithographic printing plate used in the processing method of the present invention are shown below.

  The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate used in the processing method of the present invention contains a photopolymerization initiator. As the photopolymerization initiator used in the photosensitive lithographic printing plate used in the processing method of the present invention, any compound can be used as long as it is a compound capable of generating radicals upon irradiation with light or electron beam.

  Examples of the photopolymerization initiator that can be used for the photosensitive lithographic printing plate used in the processing method of the present invention include (a) an organic boron salt compound, (b) an aromatic onium salt compound, and (c) an organic peroxide. (D) hexaarylbiimidazole compound, (e) ketoxime ester compound, (f) azinium salt compound, (g) active ester compound, (h) metallocene compound, (i) trihaloalkyl-substituted compound, (j) aroma And particularly preferred photopolymerization initiators are (a) an organic boron salt compound and (i) a trihaloalkyl-substituted compound.

  Examples of (a) organic boron salt compounds include JP-A-8-217813, JP-A-9-106242, JP-A-9-188585, JP-A-9-188686, and 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.

  (B) Examples of the aromatic onium salt compound include N, P, As, Sb, Bi, O, S, Se, Te or I aromatic onium salts. Examples of such aromatic onium salt compounds 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.

  (C) Examples of 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'-tetra ( Peroxidation of p-isopropylcumylperoxycarbonyl) benzophenone, di (tert-butyldiperoxy) isophthalate, etc. Ester systems are preferred.

  (D) Examples of hexaarylbiimidazole compounds include lophine dimers described in JP-B-45-37377 and JP-B-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) bi Imidazole, 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) -4,4 ', 5,5'-tetraphenylbiimidazole and the like.

  (E) Examples of ketoxime ester compounds 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-toluenesulfonyloxyimino) butan-2-one , 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one and the like.

  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. be able to.

  (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-1-152109 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 trihaloalkyl sulfonyl 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) Preferred examples of aromatic ketones include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY”. P. FUOASSIER, J.A. F. RABEK (1993), P.A. 77-P. 177, a compound having a benzophenone skeleton or a thioxanthone skeleton, an α-thiobenzophenone compound described in Japanese Patent Publication No. 47-6416, a benzoin ether compound described in Japanese Patent Publication No. 47-3981, and Japanese Patent Publication No. 47-22326 Α-substituted benzoin compounds described in JP-A No. 47-23664, benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, and JP-B-60-26483 Dialkoxybenzophenones, benzoin ethers described in JP-B-60-26403, JP-A-62-181345, p-di (dimethylaminobenzoyl) benzene described in JP-A-2-211452, A thio-substituted aromatic group described in JP-A-61-194062 Ton, an acylphosphine sulfide described in JP-B-2-9597, an acylphosphine described in JP-B-2-9596, a thioxanthone described in JP-B-63-61950, and JP-B-59-42864 Can be mentioned.

  The photopolymerization initiator used in the photosensitive lithographic printing plate used in the processing method of the present invention includes compounds known as photoacid generators. As the photoacid generator, any compound can be used as long as it is a compound capable of decomposing by irradiation with light or electron beam and generating a strong acid such as hydrochloric acid or sulfonic acid or an acid such as Lewis acid. Examples of the photoacid generator that can be used for the photosensitive lithographic printing plate used in the processing method of the present invention include (k) aromatic diazonium salt compound, (l) pivalic acid-o-nitrobenzyl ester, benzenesulfone. O-nitrobenzyl esters such as acid-o-nitrobenzyl ester, (m) 9,10-dimethoxyanthracene-2-sulfonic acid-4-nitrobenzyl ester, pyrogallol trismethanesulfonate, naphthoquinonediazide-4-sulfonic acid ester Sulfonate derivatives such as (n) dibenzylsulfone, sulfones such as 4-chlorophenyl-4'-methoxyphenyldisulfone, (o) phosphate ester derivatives and (p) US Pat. No. 3,332,936 Description, JP-A-2-83638, JP-A-11-322707 Publication, can be exemplified sulfonyl diazomethane compounds described in JP-2000-1469 Patent Publication.

  The organoboron salt compound that is a particularly preferred photopolymerization initiator in the photosensitive lithographic printing plate used in the processing method of the present invention is composed of an organoboron salt, and the organoboron anion constituting the organoboron salt is the following general It is represented by Formula (4).

In the formula, each of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ may be the same or different, and represents an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. To express. Of these, it is particularly preferred that one of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is an alkyl group and the other substituent is an aryl group.

  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 organoboron salt used in the photosensitive lithographic printing plate used in the processing method of the present invention is a salt containing the organoboron anion represented by the general formula (4) shown above, as a cation forming the salt. Alkali metal ions and onium compounds are preferably used. 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. Specific examples of particularly preferred organic boron salts are shown below.

  In the photosensitive lithographic printing plate used in the processing method of the present invention, a trihaloalkyl-substituted compound can be used as a photopolymerization initiator that can be further enhanced in sensitivity and 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 specific examples of trihaloalkyl-substituted nitrogen-containing heterocyclic compounds and trihaloalkylsulfonyl compounds are shown below.

  The above photopolymerization initiators may be used alone or in any combination of two or more. The content of the photopolymerization initiator is preferably in the range of 1 to 100 parts by mass and more preferably in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the polymer containing a monomer having a polymerizable double bond as a copolymerization component. Is particularly preferred.

  The photopolymerizable photosensitive layer of the photosensitive lithographic printing plate used in the processing method of the present invention preferably contains a sensitizing dye. Such a sensitizing dye sensitizes the aforementioned photopolymerization initiator to the absorption maximum wavelength of the sensitizing dye. This makes it possible to cope with exposure by various lasers (for example, a blue-violet semiconductor laser and a near infrared laser). And when the said photoinitiator is an organic boron salt, it has the characteristic that the sensitivity with respect to various laser beams becomes very high by combining with this sensitizing dye. The sensitizing dye specifically sensitizes the decomposition of the photopolymerization initiator in a wavelength range of 380 to 1300 nm, and includes various cationic dyes, anionic dyes, and merocyanine as neutral dyes having no charge. , Coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Specific examples of the sensitizing dye relating to the photosensitive lithographic printing plate used in the processing method of the present invention are shown below.

  As the sensitizing dye of the photosensitive lithographic printing plate used in the processing method of the present invention, a system that imparts photosensitivity to light in the wavelength region of 750 to 1100 nm is preferable for near infrared laser, It is necessary to have absorption in such a wavelength region, and a particularly preferable specific example used for such purpose is shown below.

  Specific examples of particularly preferable sensitizing dyes used for blue-violet semiconductor lasers having a light source at a short wavelength as sensitizing dyes for photosensitive lithographic printing plates used in the processing method of the present invention are shown below. .

  The sensitizing dyes may be used alone or in any combination of two or more. The content of the sensitizing dye is preferably in the range of 0.1 to 50 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer containing a monomer having a polymerizable double bond as a copolymerization component. The range of is particularly preferable.

  Addition of a colorant can also be preferably performed as another element constituting the photopolymerizable photosensitive layer. As a colorant, it is used for the purpose of enhancing the visibility of the image area after exposure and development processing, and various kinds of carbon black, phthalocyanine dye, triarylmethane dye, anthraquinone dye, azo dye, etc. Dyes and pigments can be used.

  About the element which comprises a photopolymerizable photosensitive layer, in addition to the above-mentioned element, other elements can be additionally contained for various purposes. For example, inorganic fine particles or organic fine particles are also preferably added for the purpose of preventing blocking of the photosensitive layer composition.

  There is a preferred range for the dry weight of the photopolymerizable photosensitive layer, preferably a dry weight ranging from 0.2 g to 5 g per square meter, most preferably 0.5 g to 3 g per square meter. It is a range.

  When the photosensitive layer is applied, it is prepared by applying and drying a coating liquid of a composition composed of the above-described elements on the hydrophilic layer. Various known methods can be used as the coating method, and examples thereof include bar coater coating, curtain coating, blade coating, air knife coating, roll coating, spin coating, and dip coating.

[Oxygen barrier layer]
The photosensitive lithographic printing plate used in the processing method of the present invention has an oxygen barrier layer on the side farther from the support than the photopolymerizable photosensitive layer. The oxygen barrier layer is a layer containing a water-soluble polymer that blocks oxygen, and a water-soluble vinyl polymer is a typical example. Of these, polyvinyl alcohol is preferably used. In particular, it is preferable to use completely saponified polyvinyl alcohol from the viewpoints of sensitivity and storage stability.

    Polyvinyl alcohol used in the oxygen barrier layer may be partially substituted with ester, ether, and acetal as long as it contains a substantial amount of unsubstituted vinyl alcohol units necessary for the development of the required water solubility. good. Similarly, a part may contain other copolymerization components. Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100% and a polymerization degree of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA -203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-405, PVA-420, PVA-613 Etc. Examples of the copolymer include 88-100% hydrolyzed polyvinyl acetate chloroacetate or propionate, polyvinyl formal, polyvinyl acetal, and copolymers thereof.

  Water is preferable as the solvent used for applying the oxygen blocking layer, but alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone may be mixed with water. The solid content concentration in the coating solution is suitably 1 to 20% by mass.

  Further, an additive such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film may be added to the oxygen barrier layer. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like.

  The dry coating amount of the oxygen barrier layer of the photosensitive lithographic printing plate used in the processing method of the present invention is selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. Preferably between 0.1 g and 3 g per square meter.

[Development processing method]
The photosensitive lithographic printing plate of the present invention is subjected to contact exposure or laser scanning exposure, and then a pattern is formed by removing non-image areas with an alkaline developer or a chemicalless developer having a pH of 10 or more. In particular, it is preferably a negative photosensitive lithographic printing plate in which the exposed portion is cross-linked so that the solubility in an alkaline developer or a chemical-less developer is lowered and an image portion is formed.

  As a development processing method for the photosensitive lithographic printing plate of the present invention, development with a chemicalless developer is preferably performed. Unlike a strong alkali developer (generally having a pH of 10 or more) containing a large amount of an alkali agent that has been generally used, the chemicalless developer is substantially free of an alkali agent. Therefore, the pH of the developer used in the water development of the present invention is 4 or more and less than 10, preferably 4 or more and 9.5 or less, more preferably 4 or more and 9 or less. Here, the phrase “substantially free of alkali agent” means that the alkali agent is 1% by mass or less, more preferably 0.1% by mass or less, based on the total mass of the developer. The developer used in the chemicalless development or 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 entire developer, and other additives include ethanol, isopropanol, Adds various organic solvents such as n-butyl cellosolve, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, benzyl alcohol, anionic, cationic, nonionic surfactants, pH buffers, preservatives, etc. You can also The amount of the additive varies depending on the type and purpose of the additive, but is preferably 10 parts by mass or less, more preferably 3 parts by mass or less with respect to 100 parts by mass of water. Furthermore, a commercially available printing plate surface protecting solution or a printing plate fountain solution can be used. In the processing method of the present invention, for example, a water washing step, a gum processing step, or the like may be performed after the above-described development processing step.

  In the development processing method described above, in the development with an alkaline developer, an alkali agent contained in an alkaline developer having a pH of 10 or more lowers the film strength of the exposed portion of the photopolymerizable photosensitive layer to some extent. Since the development with the liquid does not include an alkaline compound, damage to the exposed portion of the photopolymerizable photosensitive layer is minimized, and the printing durability of the image portion is higher. Therefore, a more preferable development processing method of the photosensitive lithographic printing plate used in the processing method of the present invention is development with a chemicalless developer.

[Preparation of photosensitive lithographic printing plate]

  Titanium dioxide, colloidal silica, and water were mixed as in the following composition, and dispersed with a homomixer at 8000 rpm for 10 minutes.

<Dispersion containing titanium dioxide dispersion>
SR-1 (Titanium dioxide particles: Sakai Chemical Industry Co., Ltd.) 10 parts by mass (solid content)
ST-PSM (Colloidal silica: manufactured by Nissan Chemical Industries, Ltd.) 2 parts by mass (solid content)
ST-C (Colloidal silica: manufactured by Nissan Chemical Industries, Ltd.) 2 parts by mass (solid content)
Adjusted to 50 parts by weight with water.

<Hydrophilic layer>
With respect to what was subjected to aqueous subbing with a subbing composition containing an epoxy compound shown in Example 4 of JP-A-60-213942 on a polyethylene terephthalate support having a thickness of 0.20 mm, The hydrophilic layer coating liquid 1 having the following composition was applied with a wire bar so that the dry solid content of the water-soluble polymer (A-5) was 0.8 g / m ² and dried using a drier.

<Hydrophilic layer coating liquid 1>
Water-soluble resin (WP-4: weight average molecular weight 100,000) 1.0 part by mass (solid content)
Cross-linking agent (H-6) 0.2 parts by mass (solid content)
Dispersion containing titanium dioxide dispersion 2.0 parts by mass (solid content)
Silica particles 0.2 parts by mass (solid content)
(Grace Devison Silo Block S500, average particle size 5.1 μm, pore volume 0.40 ml / g)
Acrylic polyol resin (WE301 manufactured by DIC Corporation) 0.24 parts by mass (solid content)
Ethanol 5.0 parts by mass The pH was adjusted to 7.0 using 1N sodium hydroxide and adjusted to 48 parts by mass with water.

<Photopolymerizable photosensitive layer / oxygen barrier layer>
The above manner resulting hydrophilic layer, the photopolymerizable photosensitive layer coating solution 20 g / m 2 ^(wet coating amount) below, the oxygen barrier layer coating solution 30 g / m 2 ^(wet coating The multilayer coating was performed in this order with a continuous coater so that the amount was equal, and drying was performed for 7 minutes in a drying zone at 50 ° C. The surface temperature of the coated product at the end of the drying zone was 50 ° C. Then, it wound up in the winding chamber immediately adjacent to the humidity control zone through the humidity control zone immediately adjacent to the end of the drying zone. Thereafter, the wound coating was heated in a heating cabinet for 24 hours to obtain a photosensitive lithographic printing plate 1. The environment of the humidity control zone, the winding chamber, and the heating chamber is 40 ° C. and 40% RH.

<Photopolymerizable photosensitive layer coating solution>
Polymer B SP-1 1.1 parts by mass (solid content)
Photopolymerization initiator BC-6 0.2 parts by mass (solid content)
Photopolymerization initiator T-9 0.05 parts by mass (solid content)
Sensitizing dye S-17 0.08 parts by mass (solid content)
0.25 parts by mass of blue pigment (solid content)
1,3-dioxolane 10ml
This was adjusted to 20 parts by mass with 1,3-dioxolane.

<Oxygen barrier coating solution>
PVA105 (manufactured by Kuraray Co., Ltd .: polyvinyl alcohol) 2.2 parts by mass (solid content)
Surfactant 0.5 parts by weight The amount was adjusted to 30 parts by weight with water.

The resulting photosensitive lithographic printing plate 1 was exposed to an image of 1500 dpi 150 lines at an exposure amount of 100 μJ / cm ² using a plate setter (VIPLAS manufactured by Mitsubishi Paper Industries Co., Ltd.) equipped with a 405 nm violet laser.

<Development processing>
P-1310T (manufactured by Dainippon Screen Mfg. Co., Ltd.) in which water is charged into all of the developing tank, the washing tank, and the gum tank, the width x length of the exposed plate is 30 ° C. and the developing condition is 15 seconds. A plate of 1000 mm was continuously produced using 450 mm and 560 mm plates, and sampling was performed every 100 plates as a plate for printing. During continuous plate making of 1000 plates, water was replenished by the amount that the liquid level was lowered. This is referred to as Comparative Example 1.

  On the other hand, in the same manner as in the above comparative example except that the fungus (Pseudomonas sp. 113P3 (accession number: FERMP-13383)) described in Japanese Patent Publication No. 3499848 was introduced into the developing tank and developed. Then, 1000 plates were made continuously, and printing plates were sampled every 100 plates. This is defined as Invention 1.

  In addition, the water described in JP-A-2006-42612 (microbacterium Levaniformans KSS11 strain (accession number: FERM-P-20081)) described in JP-A-2006-42612 was introduced into the developing tank and developed. In the same manner as in the comparative example, 1000 plates were continuously made, and printing plates were sampled every 100 plates. This is referred to as the present invention 2.

In the processing methods of the present invention 1 and the present invention 2, the amount of bacteria introduced into the developing tank was determined by measuring the absorbance of 600 nm light of the solution from a spectrophotometer, which was defined as turbidity. From the calibration curve for the turbidity of the number of bacteria, it was confirmed that the number of bacteria at this time was approximately 6 × 10 ⁸ cfu / ml.

<Print stain resistance evaluation method>
Printing stain evaluation was performed on each plate sampled every 100 plates by the processing method of Comparative Example 1 and Inventions 1 and 2 described above. For printing, the sampled plate is attached to the printing machine Ryobi 660, SLM-OD50 (Mitsubishi Paper Co., Ltd.) 2% by weight as a dampening liquid, and DIC Corporation F gloss purple (soft type) as ink. Was printed, and the printed material from the 1000th sheet to the 15,000th sheet was sampled every 1000 sheets from the start of printing. The conditions during printing are an indoor temperature of 23 ° C. and an indoor humidity of 55% RH.

<Print stain resistance evaluation criteria>
In the 1000th to 15,000th printed matter (every 1000th sheet) after the start of printing, the print stain on the non-image area was visually evaluated according to the following criteria. The results are shown in Table 1. In addition, it is excellent in dirt resistance, so that the numerical value of evaluation criteria is large.
5: No background stains are seen even after printing up to the 15,000th sheet.
4: Background stains occur in the non-image area between the 10,000th and 14,000th sheets.
3: Background stain occurs in the non-image area between the 6000th sheet and the 9000th sheet.
2: Ground stain occurs in the non-image area between the 3000th and 5000th sheets.
1: Background stains occur in the non-image area at the 2000th and below.

  As can be seen from Table 1, according to the treatment method of the present invention, it is understood that good printing stain resistance can be obtained even when the liquid is not changed for a long time.

Claims (1)

  A method for processing a photosensitive lithographic printing plate comprising a photopolymerizable photosensitive layer on a support, and having an oxygen blocking layer on a side farther from the support than the photopolymerizable photosensitive layer, A method for treating a photosensitive lithographic printing plate, comprising treating the lithographic printing plate with a treatment liquid containing a polyvinyl alcohol-degrading bacterium.