JP5274602B2 - Plate cleaning agent for planographic printing plate and plate surface processing method of planographic printing plate - Google Patents

Abstract

A plate cleaning agent is provided capable of suitably treating a plate surface without causing blinding in a lithographic printing plate obtained by platemaking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, and particularly an oxygen-blocking protective layer containing inorganic fine particles. The invention provides: an emulsified plate cleaning agent for a lithographic printing plate, which is used on a lithographic printing plate obtained by platemaking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, wherein the total cation content of a contained salt based on the total weight of the plate cleaning agent is 0.5% by weight or more, and 30% by weight or more of the cations are at least one type selected from the group consisting of potassium, cesium and rubidium based on the weight of all cations; and a plate surface treatment method for a lithographic printing plate, this method comprising: cleaning a lithographic printing plate, obtained by platemasking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, with the above-mentioned emulsified plate cleaning agent for a lithographic printing plate.

Description

  The present invention relates to a plate surface cleaning agent for a lithographic printing plate, specifically to an emulsification type plate surface cleaning agent, and more specifically, obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen-blocking protective layer. The present invention relates to an emulsion type plate surface cleaning agent used for a lithographic printing plate. The present invention also relates to a plate surface processing method for a lithographic printing plate using such an emulsion type plate surface cleaning agent.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). As described above, a difference in ink adhesion is caused on the surface of a lithographic printing plate, and after ink is applied only to an image portion, the ink is transferred to a printing medium such as paper and printed. In lithographic printing, the non-image area is moistened with fountain solution to increase the interfacial chemical difference between the image area and the non-image area, thereby increasing the ink repellency of the non-image area and the ink receptivity of the image area. Increases are made. Therefore, when the hydrophilicity of the non-image area of the lithographic printing plate deteriorates for some reason, ink often adheres to the area, so-called “soil stain” occurs, and conversely, some component adheres to the image area. In some cases, the image density of the printed matter does not increase without ink.
If the hydrophilicity deteriorates and becomes dirty, or if the ink no longer gets on the image area, the plate surface treatment of the lithographic printing plate is performed with a plate surface cleaning agent to recover these, and the hydrophilicity of the non-image area In general, it is common practice to recover the image area. Conventionally, various plate surface cleaning agents for lithographic printing plates have been proposed (see, for example, Patent Document 1 and Patent Document 2).

On the other hand, from the viewpoint of a lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin (image recording layer) is provided on a hydrophilic support has been widely used. Such a lithographic printing plate precursor is exposed through an original image such as a lithographic film, and then a portion to be an image portion of the image recording layer is left, and the other unnecessary image recording layer is made an alkaline developer or organic A lithographic printing plate is obtained by dissolving and removing with a solvent and making a plate by a method in which the surface of the hydrophilic support is exposed to form a non-image area.
In recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread, and various new image output methods corresponding to such digitization technology have come into practical use. It is coming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate (CTP) technology has been attracting attention.

As an example of the above-described lithographic printing plate precursor for CTP, a photopolymerization lithographic printing plate precursor has been proposed. Photopolymerization type lithographic printing plate precursors generally have a polymerization initiator (a compound that initiates and accelerates polymerization of a compound having a polymerizable unsaturated group by generating radicals by the energy of light, heat, or both). Therefore, in order to suppress radical deactivation due to oxygen in the air and improve the polymerization efficiency, an oxygen-blocking protective layer is usually provided on the image recording layer. Polyvinyl alcohol is well known as a component of this protective layer. In addition, it has been proposed to include inorganic fine particles in the oxygen-blocking protective layer (see, for example, Patent Document 3).
The inorganic compound used in such an oxygen-blocking protective layer partially remains on the surface of the image area after development, due to its own hydrophilicity and / or on the surface of the inorganic compound in dampening water. By adsorbing the hydrophilic component, sufficient ink receptivity on the surface of the image area is lost during printing, and as a result, the problem of ink imperfection in which the ink density on the printed matter is lowered tends to occur. The trouble that ink does not get on the image area during printing is called blinding. On the other hand, when scumming occurs during printing, processing with a plate surface cleaning agent has the disadvantage that blinding is likely to occur. So-called uneven wiping may occur.
In view of such problems, in the lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor provided with an oxygen-blocking protective layer, particularly an oxygen-blocking protective layer containing inorganic fine particles, blinding, Further, there is a demand for a plate surface cleaning agent that can be used satisfactorily without causing inconvenience such as uneven wiping.

JP 11-288104 A JP 2007-45055 A JP 2005-119273 A

  The present invention provides a planographic printing plate obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen-blocking protective layer, particularly an oxygen-blocking protective layer containing inorganic fine particles, without causing blinding. An object of the present invention is to provide a plate surface cleaning agent that can satisfactorily perform plate surface processing.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the type of cation in the plate surface cleaning agent, and further, the amount thereof is involved in the presence or absence of blinding, Therefore, by selecting a specific mode for the cation in the plate surface cleaning agent, it has been found that the occurrence of blinding can be suppressed, and the plate surface cleaning process can be carried out satisfactorily without causing unevenness of the ink in the image area. It came to complete.
Accordingly, the present invention provides an emulsion type plate surface cleaning agent for a lithographic printing plate for use in a lithographic printing plate obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen barrier protective layer, the plate surface cleaning agent The content of the total cation of the salt contained based on the total mass of is 0.5% by mass or more, and 30% by mass or more based on the mass of the total cation is at least one selected from potassium, cesium and rubidium An emulsifying type plate surface cleaning agent for a lithographic printing plate. Here, the salt includes salts such as organic salts and inorganic salts, and hydroxides.
As a preferred embodiment of the present invention, the emulsion type plate surface cleaning agent for a lithographic printing plate as described above, which is used for a lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor in which the oxygen-blocking protective layer contains inorganic fine particles There is.
The present invention further comprises washing a lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor provided with an oxygen-blocking protective layer with the above-mentioned emulsion type plate surface cleaning agent for a lithographic printing plate. It is directed to a lithographic printing plate processing method. The plate surface treatment method of the present invention is particularly suitable for treating a lithographic printing plate obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen-blocking protective layer containing inorganic fine particles.

According to the emulsification type plate surface cleaning agent of the present invention, in the lithographic printing plate obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen-blocking protective layer, various stains in a non-image area, Exhibits dirt removal capability and does not cause poor ink deposit or wiping unevenness in the image area.
According to the emulsion type plate surface cleaning agent of the present invention, a lithographic printing plate obtained by making a plate from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, particularly an oxygen-blocking protective layer containing inorganic fine particles, is obtained. The plate surface can be cleaned well and a high-quality printed product can be provided.

The emulsion type plate surface cleaning agent for a lithographic printing plate of the present invention contains a salt providing a cation as its component. Salts that provide cations for use in the present invention include inorganic salts, organic salts, hydroxides, and the like, and any of normal salts, hydrogen salts, basic salts, double salts, complex salts, and the like. Is included. The salt that provides the cation used in the present invention can be selected from known salts and hydroxides as components in the lithographic printing plate surface cleaner. The emulsification type plate surface cleaning agent for a lithographic printing plate of the present invention requires that the cation derived from the above-mentioned salt contains at least one selected from potassium (K), cesium (Cs) and rubidium (Rb). . That is, the emulsion type plate surface cleaning agent for a lithographic printing plate of the present invention needs to contain at least a salt that provides at least one cation of potassium, cesium and rubidium. Here, the cation derived from the salt contained in the emulsification type plate surface cleaning agent for lithographic printing plates of the present invention does not include a cation derived from water used for preparing the plate surface cleaning agent.
The emulsification type plate surface cleaning agent for lithographic printing plates of the present invention has a total cation content of 0.5% by mass or more, preferably 1.0% by mass or more, based on the total mass based on the total mass. In general, it is 10% by mass or less, and 30% by mass or more is at least one selected from potassium, cesium and rubidium based on the mass of the total cation.
The total cation derived from the salt included in the emulsification type plate surface cleaning agent for a lithographic printing plate of the present invention may be at least one selected from potassium, cesium and rubidium.

  The emulsification type plate surface cleaning agent for lithographic printing plates of the present invention includes, as composition examples thereof, (1) a water-soluble polymer compound, (2) phosphoric acid, polymerized phosphoric acid, a salt thereof such as an alkali metal salt, an organic phosphonic acid At least one compound selected from the group consisting of salts thereof, (3) nitric acid and / or nitrate, (4) sulfuric acid, sulfate and / or bisulfate, (5) aqueous phase containing water, and dissolving action in ink (6) comprising an oil phase containing a hydrocarbon solvent. The emulsion type plate surface cleaning agent for a lithographic printing plate of the present invention may contain (7) a surfactant, (8) a wetting agent, (9) a thixotropic agent, and (10) a pH adjuster as necessary. . In addition to the above components, preservatives, bactericides, colorants and the like may be added to the plate surface cleaning agent of the present invention.

Specific examples of the water-soluble polymer compound of the above component (1) include dextrin, cyclodextrin, alginate, fibrin derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose, methylcellulose, etc.), gum arabic, soybean polysaccharide Natural products and modified products thereof, polyvinyl alcohol and derivatives thereof, polyvinyl pyrrolidone, polyacrylamide and copolymers thereof, acrylic acid copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers Examples thereof include a polymer and a synthetic product such as a styrene / maleic anhydride copolymer.
Water-soluble soybean polysaccharide is mentioned as a film-forming polysaccharide extracted from soybean. The water-soluble soybean polysaccharide contains rhamnose, fucose, arabinose, xylose, galactose, glucose, uronic acid and the like as constituent sugars, and has an average molecular weight of 50,000 to 1,000,000. In the plate surface cleaning agent of the present invention, the content of the water-soluble soybean polysaccharide is suitably in the range of 0.5 to 20% by mass, preferably 1 to 10% by mass. The water-soluble soybean polysaccharide is dissolved in water or warm water of 50 ° C. or lower and used as a uniform aqueous solution. A method for producing such a water-soluble soybean polysaccharide is described in JP-A-5-32701. Moreover, as a commercial item of water-soluble soybean polysaccharide, Soya Five-S-LN (Fuji Oil Co., Ltd. product) etc. are mentioned. As the soybean polysaccharide that can be used in the present invention, a 10% by weight aqueous solution having a viscosity (25 ° C.) in the range of 5 to 100 cp is preferably used.
These substances can be used singly or in combination, and in order to make the plate surface cleaning agent have a preferred viscosity range (about 100 cps to about 1000 cps), the amount used is 1 to 24% by mass based on the total mass of the plate surface cleaning agent. It is suitable, More preferably, it can select from the range of 3-20 mass%.

Above as component (2) e.g. phosphoric acid, sodium phosphate, potassium phosphate, lithium phosphate, pyrophosphate, sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, triphosphate, sodium triphosphate, potassium triphosphate, triphosphate Lithium phosphate, tetraphosphate, sodium tetraphosphate, potassium tetraphosphate, lithium tetraphosphate, metaphosphate, sodium metaphosphate, potassium metaphosphate, lithium metaphosphate, trimetaphosphate, sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, hexametaphosphate , Sodium hexametaphosphate, potassium hexametaphosphate, lithium hexametaphosphate, methylene diphosphonic acid, 1-hydroxyethane 1,1-disulfonic acid, nitrilotrisphosphonic acid N-carboxymethyl N, N-di (methylenephosphonic acid), hexamethylenediamine-tetra (methylenephosphonic acid), ethylenediamine-tetra (methylenephosphonic acid), diethylenetriamine-penta (methylenephosphonic acid), N, N-di ( Carboxymethyl) -N-methylenephosphonic acid, N- (2-hydroxyethyl) -N, N-di (methylenephosphonic acid), N-hydroxymethyl-N, N′N′-ethylenediaminetris (methylenephosphonic acid), N-hydroxyethyl-N ′, N′-diethylethylenediamine-N, N, N ′, N′-tetra (methylenephosphonic acid), di (2-hydroxypropylene) triaminepenta (methylenephosphonic acid), tri (2- Hydroxypropylene) tetraamine hexa (methylene phosphonic acid) Door can be. These compounds are commercially available, for example from the Monsanto Chemical Company as “DEQUESTs” and the Philip A Hant Chemical Corp. Commercially available as "WAYPLEX" from Wayland Chemical Division). The compounds as described above can be used alone or in combination of two or more, and are 0.1 to 15% by mass, more preferably 0.5 to 10% by mass based on the total mass of the plate cleaning agent according to the present invention. It is contained so as to be in the range.

  As the component (3) nitric acid and / or nitrate used in the present invention, in addition to nitric acid, as nitrate, zinc nitrate, cobalt nitrate, magnesium nitrate, sodium nitrate, potassium nitrate, nickel nitrate, bismuth nitrate, tin nitrate, strontium nitrate, Examples thereof include metal salts of nitric acid such as cesium nitrate, rubidium nitrate, cerium nitrate, and ammonium nitrate. The use range of nitric acid and / or water-soluble metal nitrate used in the present invention is 0.1 to 10% by mass, more preferably 0.5 to 5% by weight, based on the total mass of the plate surface cleaning agent. .

Regarding the sulfuric acid, sulfate and / or bisulfate of the component (4) used in the present invention, in addition to sulfuric acid, sulfate or bisulfate is, for example, sodium sulfate, potassium sulfate, cesium sulfate, rubidium sulfate as sulfate. And aluminum sulfate. Bisulfate is represented by the general formula M (HSO ₄ ) _n (where M is a metal and n is the valence of M). For example, strontium hydrogen sulfate, potassium hydrogen sulfate, calcium hydrogen sulfate, sulfuric acid Examples include thallium hydrogen, sodium hydrogen sulfate, lead hydrogen sulfate, bismuth hydrogen sulfate, magnesium hydrogen sulfate, and rhodium hydrogen sulfate. These compounds can be used singly or in combination of two or more, and are contained in the range of 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, based on the total mass of the plate surface cleaning agent according to the present invention. It is done.
The remaining component of the aqueous phase of the plate surface cleaning agent of the present invention is water, and the amount thereof is suitably 45 to 85% by mass, more preferably 50 to 80%, based on the total mass of the plate surface cleaning agent of the present invention. % By mass.

On the other hand, the hydrocarbon solvent of component (6) can be used in combination with the oil phase of the plate surface cleaning agent of the present invention. As the component (6), a petroleum fraction usually used for washing printing ink and having a boiling point of 120 to 350 ° C. is particularly useful. Specific examples of such hydrocarbon solvents include, for example, a product of Nippon Petrochemical Co., Ltd., having a boiling point of 150 to 200 ° C., a clean sol, a dry solvent, an A solvent, a K solvent, a mineral spirit A and a high aroma 25, and a boiling point of 200. -250 ° C insecticidal solvent, fog solvent and non-sulfur solvent, No.3 solvent, boiling point 250-300 ° C, No.4 solvent, No.5 solvent, No.6 solvent, No.7 solvent, ester of tall oil fatty acid, Swazol (aromatic High boiling point solvent, manufactured by Maruzen Petrochemical Co., Ltd.), exosol (manufactured by Exxon Chemical Co., Ltd.), and exol (naphthenic solvent, manufactured by ExxonMobil). The range of use of these hydrocarbon solvents is suitably from 1 to 50% by weight, more preferably from 5 to 35% by weight, based on the total mass of the plate surface cleaning agent.
Since component (6) does not mix with the water of component (5), it is used in a sufficiently mixed and dispersed state when used. At this time, it is useful to add a surfactant of component (7) for the purpose of enhancing the dispersion stability. Surfactants that can be used in the present invention include anionic surfactants and nonionic surfactants.

  Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates. , Alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated castor oil , Sulfated tallow oil, sulfates of fatty acid alkyl esters, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfate Stealth salts, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styrylphenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, styrene-anhydrous Examples thereof include partially saponified products of maleic acid copolymers, partially saponified products of olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates. Of these, dialkyl sulfosuccinates, alkyl sulfate esters and alkylbenzene sulfonates are particularly preferably used.

  Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, Sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters , Polyglycerin fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fat Acid diethanol amides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, and trialkylamine oxides. Among them, sorbitan fatty acid partial esters, polyoxyethylenated castor oil ether, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block polymers and the like are preferably used. Two or more of these surfactants may be used in combination. Although the usage-amount of surfactant is not specifically limited, A preferable range is 0.5-10 mass% based on the total mass of a plate surface cleaning agent.

In addition to the above components, one or more wetting agents (component (8)) that impart good spreading characteristics to the plate surface cleaning agent and suppress drying and improve suitability for use are also useful. A suitable wetting agent is a compound represented by the general formula: HO— (R—O) _n —H (wherein R is C _m H _2m (m = 2 to 6) and n is 1 to 500). It is. Specific examples of preferred compounds include ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and the like. As the wetting agent, glycerin, sorbitol, pentaerythritol is useful. The amount of the wetting agent used is generally in the range of 0.5 to 10% by mass, more preferably in the range of 1 to 5% by mass, based on the total mass of the plate surface cleaning agent.

  The thixotropic agent of component (9) lowers the viscosity of the liquid due to dynamic pressure, and when it is static, the viscosity increases to improve the working characteristics when the plate surface is treated with a sponge or the like. Suitable thixotropic agents include fine powder of silicic acid, pumice, calcium carbonate, zeolite and the like. The amount used is suitably in the range of 0.5 to 10% by mass, preferably in the range of 1 to 7% by mass, based on the total mass of the plate surface cleaning agent.

  The plate surface cleaning agent of the present invention is preferably prepared acidic, specifically in the range of pH 1.0 to 4.0, preferably in the range of pH 1.5 to 4.0, more preferably in the range of pH 1.5 to 4.0. A range of 3.0 is preferred. In order to adjust to such a pH range, a pH adjuster (component (10)) can be used. As the pH adjuster, phosphoric acid, nitric acid, sulfuric acid, phosphorous acid, and organic carboxylic acid such as citric acid, acetic acid, malonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, butyric acid, maleic acid, picolinic acid and the like can be used. Moreover, you may use together the alkali which is a hydroxide of a metal hydroxide, for example, an alkali metal or an alkaline-earth metal. Examples of such metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide.

  In addition to the above components, preservatives (bactericides), colorants and the like can be added. As preservatives, phenol or derivatives thereof, formalin, imidazole derivatives, sodium dihydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one derivatives, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium salts pyridine, quinoline Derivatives such as guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, bromonitroalcohol-based examples such as 2-bromo-2-nitropropane-1,3-diol and the like can be mentioned. The preferred addition amount of the preservative is an amount that exerts stability against bacteria, mold, yeast, etc., and is generally added in the vicinity of 0.01 to 3% by mass based on the total mass of the plate surface cleaning agent. In addition, it is preferable to use two or more preservatives in combination so as to be effective against various molds and bacteria. The colorant is used for imparting a desired color tone to the plate surface cleaning agent of the present invention to give a visual contrast, and can be selected from a wide range of dyes. As a particularly preferable colorant, a color tone such as blue, purple, and red is suitably used. Specific examples include crystal violet, safranin, brilliant blue, malachite green, and acid rhodamine B. The amount used is suitably 0.0001 to 0.1% by mass, more preferably 0.0003 to 0.05% by mass, based on the total mass of the plate surface cleaning agent.

  The emulsification type plate surface cleaning agent for a lithographic printing plate of the present invention can be produced as a general emulsified O / W type or W / O type emulsion according to a conventional method.

The emulsification type plate surface cleaning agent for a lithographic printing plate of the present invention is a lithographic printing obtained by making a plate from a photopolymerization lithographic printing plate precursor provided with an oxygen-blocking protective layer, particularly an oxygen-blocking protective layer containing inorganic fine particles. It can be suitably used for a plate. An example of such a photopolymerization type lithographic printing plate precursor is described in JP-A-2005-119273.
As a structure of a photopolymerization type lithographic printing plate precursor in which the plate surface cleaning agent of the present invention can be suitably used, (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound on a support. And a planographic printing plate precursor having an oxygen-blocking protective layer containing inorganic fine particles, particularly an inorganic layered compound, in this order.

Hereinafter, the configuration, plate making and printing steps of the photopolymerizable lithographic printing plate precursor will be briefly described.
[Oxygen barrier protective layer]
The inorganic fine particles contained in the oxygen barrier protective layer are classified into spherical fine particles and layered fine particles.
[Spherical fine particles]
Inorganic spherical fine particles include metals and metal compounds such as oxides, composite oxides, hydroxides, carbonates, sulfates, silicates, phosphates, nitrides, carbides, sulfides and the like. Specific examples include at least two kinds of composites, such as glass, zinc oxide, silica, alumina, zircon oxide, tin oxide, potassium titanate, strontium titanate, aluminum borate, magnesium oxide, magnesium borate, water Aluminum oxide, magnesium hydroxide, calcium hydroxide, titanium hydroxide, basic magnesium sulfate, calcium carbonate, magnesium carbonate, calcium sulfate, magnesium sulfate, calcium silicate, magnesium silicate, calcium phosphate, silicon nitride, titanium nitride, aluminum nitride , Silicon carbide, titanium carbide, zinc sulfide and their small amounts Both such two or more composite compound thereof. Preferred examples include glass, silica, alumina, potassium titanate, strontium titanate, aluminum borate, magnesium oxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium phosphate, and calcium sulfate.
Silica fine particles are preferred. For example, Snowtex 50 (particle diameter 0.025 μm), Snowtex O-40 (particle diameter 0.025 μm), Snowtex CM (particle diameter 0.025 μm) manufactured by Nissan Chemical Industries, Ltd., Snowtex 20L (particle diameter 0.045 μm), Snowtex XL (particle diameter 0.05 μm), Snowtex YL (particle diameter 0.65 μm), Snowtex ZL (particle diameter 0.85 μm), MP1040 (particle diameter 0. 1 μm), MP2040 (particle diameter: 0.2 μm), MP3040 (particle diameter: 0.3 μm), MP1040 (particle diameter: 0.1 μm), MP4540M (particle diameter: 0.45 μm), Silicia 310 (manufactured by Fuji Silysia Chemical Ltd.) Particle diameter 1.4 μm), silicia 320 (particle diameter 1.6 μm), silicia 350 (particle diameter 1.8 μm), silicia 370 (particle diameter 3.0 μm), silicia 530 (particle diameter 1.9 μm), silicia 550 (particle diameter 2.7 μm), silicia 250 (particle diameter 2.7 μm), silicia 430 (particle diameter 2.5 μm), etc. Can be mentioned.
Inorganic-organic composite fine particles are also preferable, for example, synthetic resin particles, natural polymer particles, etc., preferably acrylic resin, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, polyethyleneimine, polystyrene, polyurethane, polyurea, polyester, polyamide Resin particles such as polyimide, carboxymethyl cellulose, gelatin, starch, chitin, chitosan, etc. More preferably, the surface of resin particles such as acrylic resin, polyethylene, polypropylene, polystyrene is coated with the above inorganic fine particles. .
Among these inorganic spherical fine particles, it is particularly preferable that the inorganic component is silica (SiO ₂ ) from the viewpoint of dispersion stability, cost, and high friction coefficient when used as a coating solution.

The inorganic spherical fine particles preferably have an average particle size of 0.001 to 1 μm, more preferably an average particle size of 0.03 to 0.5 μm, and still more preferably an average particle size of 0.001. It is 05-0.2 micrometer. If it is too large, the oxygen barrier property is remarkably lowered, so that the image forming sensitivity is lowered. Further, since the contact area of the spherical fine particles is small, the effect of increasing the friction coefficient cannot be obtained sufficiently, and deviation tends to occur. If it is too small, the structure of the inorganic layered compound cannot be disturbed, and the fog suppression effect cannot be obtained. As for the coefficient of friction, the amount of protrusion on the surface is small, so that a sufficient effect on the amount of addition cannot be obtained, and there is a problem that the balance with the image formability cannot be achieved.
The average particle size was measured by centrifugal sedimentation using a particle size distribution analyzer BI-DCP (manufactured by Brookhaven Instruments).
Content of all the inorganic spherical fine particle components contained in a protective layer becomes like this. Preferably it is 0.1-80 mass%, More preferably, it is 1-50 mass%, More preferably, it is 5-30 mass%.

[Inorganic layered fine particles]
The inorganic layered fine particles are particles having a thin flat plate shape. For example, the following general formula: A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [where A is Any of K, Na, and Ca, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.
In the mica group, examples of natural mica include muscovite, soda mica, phlogopite, biotite and sericite. Synthetic mica includes non-swelling mica such as fluor-phlogopite mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite Na or Li hectorite (Na, Li) _1/8 Mg _2/5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic smectite is also useful.

Among the inorganic layered compounds, fluorine-based swellable mica, which is a synthetic inorganic layered compound, is particularly useful. That is, this and swelling synthetic mica, montmorillonite, saponite, hectorite, swelling clay minerals such as bentonite have a stratiform structure comprising a unit crystal lattice layer having thickness of approximately 10 to 15 angstroms, the lattice metal atom substitution is significantly greater than other clay minerals. As a result, the lattice layer is deficient in positive charges, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers in order to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , since the ionic radius is small, the bond between the layered crystal lattices is weak, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have a strong tendency and are more useful. In particular, swellable synthetic mica is preferably used.
As the shape of the inorganic layered compound to be used, from the viewpoint of diffusion control, the thinner the better, the better the plane size as long as the smoothness of the coated surface and the transmittance of actinic rays are not hindered. . Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio represents “major diameter / thickness of particle” and can be measured, for example, from a projection drawing of a particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

As for the particle diameter of the inorganic layered compound to be used, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.
When the inorganic layered compound particles having such a large aspect ratio are contained in the oxygen-blocking protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. The oxygen-blocking protective layer is prevented from deteriorating, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor is not deteriorated due to changes in humidity, and the storage stability is excellent.
The content of the inorganic stratiform compound in the protective layer is preferably 5/1 to 1/100 by mass ratio with respect to the amount of the binder used in the protective layer. Even when a plurality of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

It is preferable to use a binder together with the inorganic fine particles in the oxygen barrier protective layer.
The binder is not particularly limited as long as it has good dispersibility of inorganic fine particles, for example, layered fine particles, and can form a uniform film in close contact with the image recording layer. Water-soluble polymers and water-insoluble polymers are not particularly limited. Any of these can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, starch Examples thereof include water-soluble polymers such as derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane. These may be used in combination of two or more as required.
Of these, water-soluble polymers are preferable from the viewpoint of easy removal of the protective layer remaining in the non-image area and handling properties during film formation, and water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid. Acrylic resin, gelatin, gum arabic, and the like are preferable. Among them, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin can be applied from the viewpoint of being able to be applied using water as a solvent and easily removed by dampening water during printing. More preferred are gum arabic and the like.

  The polyvinyl alcohol that can be used in the oxygen-blocking protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of unsubstituted vinyl alcohol units having the required water solubility. Similarly, a part may contain other copolymerization components. Specific examples of polyvinyl alcohol include those having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA124H, PVA-CS, PVA-CST, PVA-HC, PVA- manufactured by Kuraray Co., Ltd. 203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, L-8 etc. are mentioned. Examples of the copolymer include 88-100 mol% hydrolyzed polyvinyl acetate chloroacetate or propionate, polyvinyl formal, polyvinyl acetal, and copolymers thereof.

The inorganic fine particles, for example, layered fine particles are dispersed in water by an appropriate method, and an oxygen-blocking protective layer coating solution is prepared from this dispersion. In addition to the above components, known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the oxygen barrier protective layer coating solution. The prepared oxygen barrier protective layer coating solution is applied on the image recording layer provided on the support and dried to form an oxygen barrier protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the oxygen-blocking protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 is applied. be able to. Specific examples of the oxygen barrier protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.
The coating amount of the oxygen blocking protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / m ^2, more preferably in the range of 0.02 to 3 g / m ^2, and most preferably Is in the range of 0.02 to 1 g / m ² .

Component constituting the image recording layer [(A) actinic ray absorber]
An actinic ray absorber is a compound that absorbs light emitted from an exposure light source, efficiently generates radicals from a polymerization initiator in photon mode and / or heat mode, and contributes to improvement in sensitivity of a lithographic printing plate precursor. . The actinic ray absorber is preferably an infrared absorber when the lithographic printing plate precursor is imagewise exposed with an infrared laser, and a wavelength of 250 to 420 nm when the lithographic printing plate precursor is exposed imagewise with an ultraviolet laser. Sensitizing dyes that absorb the light are preferred. The infrared absorber is preferably a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm. Such an infrared absorber can be appropriately selected from known ones.

Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Furthermore, cyanine dyes and indolenine cyanine dyes are preferred.
These infrared absorbers are added in a proportion of 0.001 to 50% by mass, preferably 0.005 to 30% by mass, particularly preferably 0.01 to 10% by mass, based on the total solid content of the image recording layer. Can do. Within this range, high sensitivity can be obtained without adversely affecting the uniformity and film strength of the image recording layer.

Further, a sensitizing dye may be used, and the sensitizing dye used is a compound having absorption at a wavelength of 250 to 420 nm. Specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, and 9-fluorenone. 2-chloro-9-fluorenone, 2-methyl-9-fluorenone, 9-anthrone, 2-bromo-9-anthrone, 2-ethyl-9-anthrone, 9,10-anthraquinone, 2-ethyl-9, 10 -Anthraquinone, 2-t-butyl-9,10-anthraquinone, 2,6-dichloro-9,10-anthraquinone, xanthone, 2-methylxanthone, 2-methoxyxanthone, thioxanthone, benzyl, dibenzalacetone, p- (Dimethylamino) phenylstyryl ketone, p- (dimethylamino) phenyl p Methyl styryl ketone, benzophenone, p- (dimethylamino) benzophenone (or Michler's ketone), p- (diethylamino) benzophenone, and the like benzanthrone.
These sensitizing dyes are preferably from 0.1 to 50% by mass, more preferably from 0.5 to 30% by mass, particularly preferably from 0.8 to 20% by mass, based on the total solid content constituting the image recording layer. Can be added.

[(B) Polymerization initiator]
A polymerization initiator is a compound that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating radicals by energy of light, heat, or both. Examples of the polymerization initiator that can be used include a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, and a photopolymerization initiator.
Examples of the polymerization initiator as described above include organic halogen compounds, carbonyl compounds, organic peroxides, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, and oximes. Examples thereof include ester compounds, oxime ether compounds, and onium salt compounds.
The polymerization initiator used preferably has a maximum absorption wavelength of 400 nm or less. More preferably, the maximum absorption wavelength is 360 nm or less, and most preferably 300 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the white light safety of the lithographic printing plate precursor is improved.
These polymerization initiators are added in a proportion of 0.1 to 50% by mass, preferably 0.5 to 30% by mass, particularly preferably 1 to 20% by mass, based on the total solid content constituting the image recording layer. Can do. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained. These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

[(C) Polymerizable compound]
The polymerizable compound used in the image recording layer is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one terminal ethylenically unsaturated bond, preferably two or more. . Such a compound group is widely known in the industrial field, and these can be used without any particular limitation. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

About these polymerizable compounds, the details of usage such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. Further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, polymerization initiator, colorant, etc.), the selection and use method of the polymerizable compound is an important factor, For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion to the support or the oxygen barrier protective layer.
The polymerizable compound is used in the image recording layer in an amount of preferably 5 to 80% by mass, more preferably 25 to 75% by mass. These may be used alone or in combination of two or more. In addition, the usage of the polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. The layer construction and coating method such as undercoating and overcoating can also be carried out.

[Other components of image recording layer]
In the image recording layer, components other than the above (A), (B), (C), for example, binder polymer, surfactant, colorant, print-out agent, polymerization inhibitor (thermal polymerization inhibitor), higher fatty acid Derivatives, plasticizers, inorganic fine particles, low molecular weight hydrophilic compounds and the like can be contained.
For example, as the binder polymer, a conventionally known one can be used without limitation, and a linear organic polymer having a film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.
A binder polymer may be used independently or may be used in mixture of 2 or more types. The content of the binder polymer is preferably 10 to 90% by mass and more preferably 20 to 80% by mass with respect to the total solid content of the image recording layer. Within this range, good image area strength and image formability can be obtained. Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 1 / 9-7 / 3 by mass ratio.

In the image recording layer, a surfactant can be used in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.
Surfactant can be used individually or in combination of 2 or more types. The surfactant is preferably contained in the image recording layer in an amount of 0.001 to 10% by mass, and more preferably 0.01 to 5% by mass.

In the image recording layer, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc., and JP-A-62-2 And dyes described in Japanese Patent No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.
These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The amount added is preferably 0.01 to 10% by mass in the image recording layer.

  In the image recording layer, a compound that changes color by an acid or a radical can be added in order to generate a printout image. As such a compound, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

In order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during production or storage of the image recording layer, it is preferable to add a small amount of a thermal polymerization inhibitor to the image recording layer.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t- (Butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), and N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The thermal polymerization inhibitor is preferably contained in the image recording layer in an amount of about 0.01 to about 5% by mass.

  In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to the image recording layer, and it is unevenly distributed on the surface of the image recording layer in the drying process after coating. Also good. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

The image recording layer is formed by dispersing or dissolving the above-described constituents in an appropriate solvent to prepare a coating solution and coating it.
The image recording layer can be formed by preparing a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents, and repeating a plurality of coatings and dryings.
Image recording layer coating weight (solids) is preferably from ^{0.3~1.5g / m 2, 0.5~1.5g / m} 2 is more preferable.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

The support used for the lithographic printing plate precursor is not particularly limited as long as it is a dimensionally stable plate. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.
The lithographic printing plate precursor may be further provided with a back coat or an undercoat layer.

[Prepress, print]
A lithographic printing plate precursor as described above is exposed imagewise by exposure through a transparent original having a line image, a halftone dot image or the like, or by laser scanning exposure with digital data. Examples of the exposure light source include a carbon arc, a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a halogen lamp, an ultraviolet light laser, a visible light laser, and an infrared light laser. A laser is particularly preferable, and examples thereof include a solid-state laser and a semiconductor laser that emit infrared light of 760 to 1200 nm, and a semiconductor laser that emits light of 250 to 420 nm. When a laser is used, scanning exposure is preferably performed in an image-like manner according to digital data. In order to shorten the exposure time, it is preferable to use a multi-beam laser device.

The method of using the fountain solution for the lithographic printing plate is not particularly limited. After the exposure of the lithographic printing plate precursor as described above, the unnecessary image recording layer is dissolved and removed with a suitable developer, and then printing can be performed by supplying oil-based ink and fountain solution to the plate surface.
Alternatively, after the above-described lithographic printing plate precursor is imagewise exposed with laser light, printing can be performed by supplying oil-based ink and fountain solution without any development processing steps. That is, a so-called on-press development method in which a non-image portion is removed on a printing machine to obtain a lithographic printing plate during the printing process can be employed.
Specifically, after exposing a lithographic printing plate precursor with a laser beam, mounting it on a printing machine without passing through a development processing step, after mounting the lithographic printing plate precursor on a printing machine, on the printing machine Examples include a method of performing exposure with laser light and printing without going through a development processing step.

After exposing the lithographic printing plate precursor imagewise with a laser beam and supplying it with dampening water and oil-based ink without passing through a development process such as a wet development process, the exposed part of the image recording layer The image recording layer cured by exposure forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured image recording layer is dissolved or dispersed and removed by the supplied dampening water and / or oil-based ink, and a hydrophilic surface is exposed in that area. As a result, the fountain solution component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, dampening water or oil-based ink may be supplied to the printing plate first, but the dampening water is first oil-based in order to prevent the dampening water from being contaminated by the image recording layer in the unexposed area. It is preferable to supply ink.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

The emulsification type plate surface cleaning agent for lithographic printing plates of the present invention should be used for removing background stains caused by the causes that have occurred at all stages from plate making to printing, during plate making or after storage, during printing, etc. Can do.
In order to use the emulsification type plate surface cleaning agent for a lithographic printing plate of the present invention, it is necessary to wipe it with a cloth, a sponge, etc., wipe the soiled portion or the entire plate surface, then leave it for about 30 seconds, and then wipe it off with water. .

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. “Parts” and “%” represent parts by mass and mass%, respectively, unless otherwise specified.
[Preparation of emulsifying type plate surface cleaning agent]
Example 1
5 parts by mass of water-soluble soybean polysaccharide was dissolved in 53 parts by mass of pure water while heating. Next, 2 parts by mass of sodium metaphosphate was dissolved while stirring, and sulfuric acid: 0.5 part by mass, nitric acid: 0.5 part by mass: potassium hydroxide: 3 parts by mass were added and mixed to prepare an aqueous phase. Further, phosphoric acid was added little by little to adjust the aqueous phase to pH 2.0. On the other hand, 15 parts by mass of Swazol 1000, 15 parts by mass of Exol D-40, 2 parts by mass of Perex OT-P, 1 part by mass of Nonion OP-80, and 1 part by mass of Pionin D-212, dissolved oil phase Was prepared. Next, the aqueous phase prepared as described above was stirred and heated and adjusted to 35 ° C., and the oil phase was slowly added dropwise to prepare a dispersion, and a milky white emulsion type plate cleaning agent was prepared through a homogenizer.
The plate surface cleaning agent thus obtained had the same pH 2.0 as that of the aqueous phase.

Examples 2 to 6, Reference Example 1 and Comparative Examples 1 to 12
An emulsion type plate surface cleaning agent was prepared in the same manner as in Example 1 except that the composition was changed.
The compositions of the emulsion type plate surface cleaning agents of Examples 1 to 6, Reference Example 1 and Comparative Examples 1 to 12 are shown in the following Tables 1 to 3 (unit of composition: parts by mass). In addition, the pH value of each emulsification type plate surface cleaning agent, the total cation amount derived from the contained salt (mass%), and the ratio (mass%) of at least one selected from potassium, cesium and rubidium based on the total cation amount Describe together.

[Creation of lithographic printing plate precursor]
(1) Preparation of support In order to remove rolling oil on the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution. After that, the aluminum surface was grained using ^three bundle-planted nylon brushes having a bristle diameter of 0.3 mm and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. . This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed in an aqueous solution containing 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. with an aluminum plate serving as an anode with an electric quantity of 50 C / dm ² In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, the plate was provided with a DC anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolyte, and then washed with water. It dried and produced the support body (1).
Thereafter, in order to ensure the hydrophilicity of the non-image area, the support (1) was subjected to a silicate treatment at 60 ° C. for 10 seconds using an aqueous 2.5 mass% No. 3 sodium silicate solution, and then washed with water for support. Body (2) was obtained. The adhesion amount of Si was 10 mg / m ² . The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

(2) Formation of undercoat layer Next, the following undercoat layer coating solution (1) is applied onto the support (2) so that the dry coating amount is 20 mg / m ² , and used in the following experiments. A support having a layer was prepared.
<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Water 6.15g

(3) Formation of image recording layer The image recording layer coating solution (1) having the following composition was bar-coated on the undercoat layer formed as described above, and then oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount. An image recording layer of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

<Photosensitive solution (1)>
-Binder polymer (1) [the following structure] 0.240 g
Infrared absorbing dye (1) [the following structure] 0.030 g
-Radical generator (1) [the following structure] 0.162 g
-Radical polymerizable compound Tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate 0.062g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
-Sensitizing agent Ammonium group-containing polymer [the following structure, reduced specific viscosity 44 cSt / g / ml] 0.035 g
・ Fluorosurfactant (1) [The following structure] 0.008g
・ 2-butanone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution (1)>
・ Microgel (1) 2.640 g
・ Distilled water 2.425g

  The binder polymer (1), infrared absorbing dye (1), radical generator (1), phosphonium compound (1), low molecular weight hydrophilic compound, (1) ammonium group-containing polymer, and fluorosurfactant ( The structure of 1) is as shown below.

-Synthesis of microgel (1)-
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (Mitsui Chemical Polyurethane Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was designated as the microgel (1). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

(4) Formation of Protective Layer Further, a protective layer coating solution (1) having the following composition was further bar-coated on the image recording layer, followed by oven drying at 125 ° C. for 75 seconds, and a dry coating amount of 0.15 g / m ^2. A lithographic printing plate precursor was obtained by forming a protective layer.
Coating liquid for protective layer (1)
・ Polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd.) 0.16 g
(Saponification degree 81.5 mol%, polymerization degree 500)
・ Terminal sulfonic acid-modified polyvinyl alcohol CKS-50 0.49 g
(Nippon Synthetic Chemical Industry Co., Ltd.)
-EMALEX 710 (manufactured by Nippon Emulsion Co., Ltd., surfactant) 0.13 g
・ Inorganic layered compound dispersion (1) 22.28 g
Colloidal silica MP1040 (manufactured by Nissan Chemical Industries / average particle size 0.1 μm / 40 mass% aqueous solution)
0.30g
・ Ion-exchanged water 52g

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.
Thus, a photopolymerization planographic printing plate precursor in which an oxygen-blocking protective layer containing an inorganic stratiform compound was provided on the image recording layer was obtained.

[Test method]
Using the photopolymerization type lithographic printing plate precursor obtained as described above, plate making was performed by on-press development under the following printing condition 1 or printing condition 2, and then the performance of various plate surface cleaning agents was tested.
<Printing condition 1>
Printing machine: Heidelberg MOV (Alcolor water supply device)
Ink: Toyo Ink Co., Ltd. Environmentally Friendly NonVOC Ink Name TK NEX NV100 Process Red Ink Dampening Water: FUJIHUNT Dampening Water PressMax 30.33 was diluted to 4% and used.
Plate making conditions: Thermal laser setter CREO Quantum is used to burn the image of the FM screen TAFFTA20, then it is attached to the printing machine, dampening water and ink are supplied to complete on-machine development, and printing is performed as follows A test was conducted.
<Dirt removal>
The following processing (1, 2, 3) was applied to the non-image area on the plate that had been subjected to on-press development.
When printing was resumed, ink adhered to the treated area, resulting in smearing. Various plate surface cleaning agents were soaked into the sponge, the entire plate surface was wiped 5 times, the stain was removed, and printing was resumed. The soil recovery was evaluated.
1. Air oxidation stain: Stored in a dryer at 150 ° C. for 3 hours without applying gum.
2. Scratch dirt: Using a scratch tester (manufactured by Shinto Kagaku Co., Ltd.), the diamond needle 4R was scratched with a load of 100 g, 200 g, and 300 g and left in the atmosphere for 3 days.
3. Oil stain: 1 g of oleic acid was dissolved in 10 g of mineral spirit, dipped in absorbent cotton and buff dried.

The recoverability with respect to the above various stain treatments 1 to 3 was evaluated according to the following criteria.
1. Air oxidation stain removability: Evaluation of stain removal state with 100th printed material ○… Excellent Δ… Slightly inferior ×… Inferior Scratch dirt: Evaluation of the state of dirt on the scratched part with the 100th printed material ○ ・ ・ ・ Excellent Δ ・ ・ ・ Slightly inferior × ・ ・ ・ Inferior Oil stain: Evaluate the state of removal of dirt with the 100th printed material ○ ・ ・ ・ Excellent △ ・ ・ ・ Slightly inferior × ・ ・ ・ Inferior

<Printing condition 2>
Printing machine: New DAIYA made by Mitsubishi Heavy Industries
Ink: Sheet ink name of DIC Graphic Co., Ltd. Process G ink of Fusion G Dampening solution: Dampening solution manufactured by FUJIHUNT PressMax 30.33 was diluted to 4% and used.
Plate making conditions: Thermal laser setter CREO Quantum is used to burn the image of the FM screen TAFFTA20, then it is attached to the printing machine, dampening water and ink are supplied to complete on-machine development, and printing is performed as follows A test was conducted.
<Ink ride>
On the plate that had been developed on-press, 1000 sheets were printed, and the press was stopped. Various plate surface cleaners were soaked in the sponge, the entire plate surface was wiped 5 times, and printing was resumed. Ink printing on the solid image portion and the halftone image portion during printing 2000 sheets from the start was evaluated according to the following criteria from the viewpoints of occurrence of wiping unevenness and ink deposition.
4). Occurrence of wiping unevenness: Evaluated by the number of printed sheets from the start until the wiping unevenness disappears .... 50 or less sheets until the wiping unevenness does not come out from the start or disappears.・ ・ ・ 100-500 sheets printed until the wiping unevenness disappears △ × ・ ・ 500 or more sheets printed until the wiping unevenness disappears. Ink fillability: Evaluated by the number of prints from the start until the ink is completely deposited ○ ・ ・ ・ Completely ink deposit with less than 50 sheets ○ △ ・ ・ Print 50-100 sheets until complete ink deposit △ ・・ ・ Print 100-500 sheets until complete ink deposition △ × ・ ・ Print more than 500 sheets until complete ink deposition × ・ ・ ・ Even after printing 2000 sheets, complete ink deposition cannot be obtained. It is described according to the following table.

ノニオン ＯＰ−８０（モノオレイン酸ソルビタン、日本油脂）
パイオニン Ｄ−２１２（ポリオキシエチレンヒマシ油エーテル、竹本油脂） The components included in the oil phase are as follows.
Swazol 1000 (Aromatic high boiling point solvent, Maruzen Petrochemical)
Swazol 1500 (Aromatic high boiling point solvent, Maruzen Petrochemical)
Swazol 2000 (Aromatic high boiling point solvent, Maruzen Petrochemical)
Exol D-40 (Naphthenic solvent, ExxonMobil)
Exol D-80 (Naphthenic solvent, ExxonMobil)
Exol D-110 (Naphthenic solvent, ExxonMobil)
Perex OT-P (sodium dialkylsulfosuccinate, Kao)
70% active ingredient

Nonion OP-80 (Sorbitan monooleate, Japanese fat)
Pionein D-212 (polyoxyethylene castor oil ether, Takemoto oil)

Claims (5)

An emulsifying type plate surface cleaning agent for a lithographic printing plate used for a lithographic printing plate obtained by making a plate from a photopolymerization type lithographic printing plate precursor provided with an oxygen barrier protective layer, based on the total mass of the plate surface cleaning agent The total cation content of the salt contained is 2.38 % by mass or more, and 30% by mass or more based on the mass of the total cation is at least one selected from potassium, cesium and rubidium. An emulsion type plate surface cleaning agent for lithographic printing plates. The emulsion type plate surface washing agent for lithographic printing plates according to claim 1, wherein the content of all cations of the salt contained based on the total mass of the plate surface washing agent is 10% by mass or less. The emulsion type plate surface cleaning agent for a lithographic printing plate according to claim 1 or 2 , wherein the oxygen barrier protective layer is used for a lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor containing inorganic fine particles. The lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor provided with an oxygen-blocking protective layer is obtained with the emulsion type plate surface cleaning agent for a lithographic printing plate according to any one of claims 1 to 3 . A plate surface processing method for a lithographic printing plate, comprising washing. The lithographic printing plate processing method according to claim 4 , wherein a lithographic printing plate obtained by making a plate from a photopolymerization lithographic printing plate precursor provided with an oxygen-blocking protective layer containing inorganic fine particles is washed.