JPH0529111B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a method for producing a lithographic printing plate material suitable for use in electrophotographic engraving. (b) Prior art and problems to be solved by the invention Conventionally, lithographic printing plate materials used in electrophotographic engraving have been provided with a zinc oxide photoconductive layer on the surface of a base material such as metal foil or paper. is used. This is generally referred to as master paper.
An electrostatic latent image is formed on a zinc oxide photoconductive layer, and then lipophilic developing powder (toner) is attached to the electrostatic latent image to form an image area to form a lithographic printing plate.
By the way, since the zinc oxide lead photoconductive layer is exposed in the non-image area, it is necessary to make this area hydrophilic to prevent printing ink from adhering to it. This is done by applying it to the image area. However, after forming the image area, selectively applying a processing agent only to the non-image area is a troublesome task, and there is a risk that the processing agent will also be applied to the image area, making the image area hydrophilic as well. It was hot. Therefore, the present invention has been made for the purpose of obtaining a lithographic printing plate material that does not require applying various processing agents only to non-image areas after forming an image area, and the lithographic printing plate material obtained by the present invention Printing plate materials are made hydrophilic to non-image areas through conventional so-called development treatment. (d) Means and action for solving the problems That is, the present invention provides an organic solvent with (a) the general formula RSi(OH) ₃ (wherein R is 1 to 3 carbon atoms).
alkyl group, gamma-macrolopropyl group, vinyl group, 3,3,3-trifluoropropyl group, gamma-glycidoxypropyl group, gamma-methacryoxypropyl group, gamma-mercaptopropyl group, and phenyl group. )
A partial condensate of silane triol represented by: (b) polyvinyl alcohol with a degree of saponification of 30 to 60%, (c) a crosslinked product of an alkali salt of polyacrylic acid, and (d) an inorganic powder insoluble in organic solvents. A composition obtained by dissolving or dispersing and is applied to a substrate and dried to form an intermediate layer, and then a liquid adhesive in which a photoconductive substance is dispersed is applied to the intermediate layer, and then dried. The present invention relates to a method for producing a lithographic printing plate material, which is characterized by forming a surface layer. Component (a) used in the present invention is a partial condensate of silane triol. Specific examples of silane triols are as follows. _CH3Si (OH _{) 3} , C2H5Si ₍ OH) ₃ , _C3H7Si (OH) ₃ , (CH) ₃ , _CH2 =CHSi(OH _{) 3} , _{C6H5Si ( OH3} ) ₂ CHSi(OH) ₃ , F ₃ C-(CH ₂ ) ₂ Si(OH) ₃ , Cl(CH ₂ ) ₃ Si(OH) ₃ , H ₂ C=C(CH ₃ )COO(CH ₂ ) ₃ Si(OH) ₃ , HS(CH ₂ ) ₃ Si(OH) ₃ , Component (A) is obtained by partially condensing these silane triols alone or in combination. Partial condensation (partial condensate) is
This refers to a state in which the hydroxyl groups of the silane triol are not completely reacted, and a considerable amount of hydroxyl groups remains, for example, about 1 mole per 3 moles of silicon atoms. As the silane triol used in the present invention, it is most preferable to use monomethylsilane triol. A partial condensate of monomethylsilane triol is produced by adding monomethyltrialkoxysilane to a water-alcohol mixed solvent. As the alkoxy group, methoxy group, ethoxy group,
A propoxy group, an isopropyl group, etc. can be used. The reaction mechanism is that monomethylalkoxysilane is hydrolyzed and the resulting monomethylsilane triol is condensed. This condensation is not carried out completely in a water-alcohol mixed solvent, but is carried out partially to obtain a partial condensate of monomethylsilane triol. When the partial condensate of silane triol is heated or dried, the remaining hydroxyl groups are condensed to form a three-dimensional network polymer with an (O-Si-O) structure as a backbone, and it becomes a substrate for the intermediate layer of a lithographic printing plate material. This is the result. When curing the partial condensate of silane triol, it is preferable to use a curing catalyst such as an alkali metal salt of a carboxylic acid such as sodium acetate, an amine carboxylate, or a quaternary ammonium carboxylate because it facilitates curing. The component (b) used in the present invention has a saponification degree of 30
~60% polyvinyl alcohol. saponification degree
If it exceeds 60%, it becomes insoluble in organic solvents, which is undesirable, and if it exceeds 30%, the degree of hydrophilicity is low, which is not preferred. Polyvinyl alcohol mainly improves the hydrophilicity of the intermediate layer of lithographic printing plate materials. Component (iii) used in the present invention is a crosslinked product of an alkali salt of polyacrylic acid. Examples of the alkali salt of polyacrylate include sodium polyacrylate and calcium polyacrylate.
In the present invention, this polyacrylic acid alkali salt is crosslinked with a crosslinking agent. Examples of crosslinking agents include diglycidyl ether compounds such as ethylene glycol diglycidyl ether, propylene glycol dicrycidyl ether, and glycerin diglycidyl ether, haloepoxy compounds such as epichlorohydrin, epibromhydrin, and α-methylepichlorohydrin, glutaraldehyde, glyoxal, etc. Isocyanate compounds such as aldehyde compounds, 2,4-tolylene diisocyanate, and hexamethylene diisocyanate are used. The crosslinked polyacrylic acid alkali salt improves the hydrophilicity of the intermediate layer of the lithographic printing plate material and also improves the retention of dampening water. Inorganic powders that are insoluble in organic solvents and are component (2) used in the present invention may be those that are insoluble in organic solvents or have extremely low solubility, such as zinc oxide, aluminum oxide, antimony oxide, and calcium oxide. , metal or non-metal oxides such as chromium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, lead oxide, bismuth oxide, magnesium oxide, manganese oxide, salts such as calcium carbonate and calcium sulfate, silicon such as silicon dioxide, etc. Examples include compounds, natural pigments such as kaolin, bentonite, and clay, and various metal powders such as aluminum, iron, and zinc. When inorganic powder insoluble in organic solvents is present in the intermediate layer of a lithographic printing plate material, it forms fine irregularities on the surface of the intermediate layer. Further, the particle size of the inorganic powder may be about 320 mesh passes, and the smaller the particle size, the more preferable it is. The composition used in the present invention can be obtained by uniformly dissolving or dispersing the components (a) to (d) described above in an organic solvent. Examples of organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,
Alcohols such as t-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, mixed solvents of these alcohols and water, acetic acid, ethyl acetate, butyl acetate, methyl ethyl ketone, Methyl isobutyl ketone, ethyl cellosolve, butyl cellosolve, acetic acid cellosolve,
Toluene, xylene, trichloroethylene, chloroform, acetone, tetrahydrofuran, ethylene glycol monoethyl ether acetate,
Ethylene glycol dimethyl ether and the like can be used alone or in combination. In preparing the composition used in the present invention, for example, a trialkoxysilane such as monomethyltrialkoxysilane is added to a water-alcohol mixed solvent, and the silane, which is the component (a), is hydrolyzed and condensed. A partial condensate of triol is generated, and then the (b) component saponification degree is 30.
~60% polyvinyl alcohol, component (3), a cross-linked product of polyacrylic acid alkali salt, and component (2), inorganic powder insoluble in organic solvents, are added, and if necessary, chelating agents, pigments, and dyes are added. , a thickener, etc. may be added and vigorous stirring may be performed to defoam. The quantitative proportions of each component in the composition used in the present invention are preferably as follows. That is,
The amount of polyvinyl alcohol is silane triol
Polyvinyl alcohol 50-200 parts per 100 parts by weight
It is about 80 to 180 parts by weight, more preferably about 80 to 180 parts by weight. If the amount of polyvinyl alcohol is less than 50 parts by weight, the hydrophilicity of the intermediate layer tends to be insufficient.
Moreover, if it exceeds 200 parts by weight, the intermediate layer may melt and cause printing stains. The amount of crosslinked polyacrylic acid alkali salt is silane triol 100
It is about 50 to 200 parts by weight, more preferably about 80 to 150 parts by weight. If the amount of polyacrylic acid alkali salt is less than 50 parts by weight, the ability to retain dampening water on the surface of the intermediate layer will decrease and the hydrophilicity will tend to decrease, and if it exceeds 200 parts by weight, it will retain dampening water. There is a tendency that the ability to do so does not increase, resulting in uneconomical results. Further, the amount of the inorganic powder insoluble in the organic solvent is about 30 to 150 parts by weight, preferably about 50 to 120 parts by weight, based on 100 parts by weight of silane triol. If the amount of the inorganic powder insoluble in the organic solvent is less than 30 parts by weight, the unevenness of the surface of the intermediate layer of the lithographic printing plate material tends to vary, and the adhesion of the liquid adhesive applied later tends to vary as well. There is a tendency to Furthermore, even if the amount exceeds 150 parts by weight, the adhesion of the liquid adhesive applied later cannot be improved much, and adding more than this tends to be uneconomical. As the base material for applying the composition used in the present invention, any material may be used as long as it is inexpensive and satisfies the required performance as a lithographic printing plate, such as aluminum, iron, copper, zinc, Foils or plates made of single metals such as lead or alloys thereof,
Plastic film or sheet-like molded products such as polyester, polypropylene, polyimide, polyacrylonitrile, polycarbonate, polyamide, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, etc., synthetic materials, art paper, coated paper, cardboard, thin paper, etc. Various types can be used. Aluminum, zinc, iron, etc. are suitable as the metal base material. As the plastic base material, polyethylene, polyimide, and polycarbonate, which have relatively high dimensional stability, are suitable. As the paper base material, synthetic paper, coated paper, art paper, and cardboard are suitable. When applying the composition used in the present invention to a metal base material, for the purpose of increasing the adhesive strength with the base material,
5-sulfosalicylic acid, ethylenediaminetetraacetic acid, trans-cyclohexane-1,2-diaminetetraacetic acid, butane-1,2,3,4-tetracarboxylic acid, propylenediaminetetraacetic acid,
Chelating agents such as pentamethylenediaminetetraacetic acid, cyclopentane-1,2-diaminetetraacetic acid, cyclohexane-1,4-diaminetetraacetic acid, and 2-hydroxytrimethylenediaminetetraacetic acid are added to the composition used in the present invention. You can leave it there. Further, the substrate does not need to be pretreated prior to application of the composition used in the present invention, unless the surface thereof is contaminated with oily substances. If necessary, the specific surface area of the substrate surface can be reduced by physically treating the surface of the substrate by wet or dry hoing, ball polishing, brush polishing, etc., or by chemically treating it by chemical conversion treatment with acid or alkali. Of course, there is no problem in increasing it. After the composition is applied to the substrate in this manner, it is dried to form an intermediate layer on the substrate, and then a liquid adhesive is applied to this intermediate layer. A photoconductive substance is dispersed in the liquid adhesive. As photoconductive substances, powdered zinc oxide,
Silicon, germanium, arsenic, tellurium, selenium, gallium arsenide, cadmium sulfide, cadmium selenide, lead sulfide, lead telluride, gallium arsenide,
Inorganic substances such as selenium-tellurium mixed crystals and arsenic-selenium-tellurium mixed crystals, or organic substances such as berimide, oxathiazole, polyvinylcarbazole, polyvinylpyrene, polyvinyl acridine, polyacenaphthylene, and polyvinylanthracene can be used. In addition, when using an organic substance, it is common to use a sensitizer such as trinitrofluorene, triallylcarbonium salt, benzopyrylium salt, crystal violet, etc. in combination. This photoconductive substance imparts photoconductivity to the surface layer of the lithographic printing plate material and enables the formation of an electrostatic latent image. The liquid adhesive in which the photoconductive substance is dispersed is one in which a high molecular weight polymer is dissolved in an organic solvent or water. As the polymer, methylcellulose, ethylcellulose, polyvinyl acetate, polyvinyl chloride, etc. are used. Furthermore, as the organic solvent, methyl alcohol, ethyl alcohol, propyl alcohol, acetone, etc. are used. The amount of photoconductive substance in the liquid adhesive is about 5 to 100 parts by weight, preferably about 10 to 50 parts by weight, based on 100 parts by weight of the high molecular weight polymer. When the amount of the photoconductive substance is less than 5 parts by weight, it tends to be difficult to form an electrostatic latent image on the surface of the lithographic printing plate material. Moreover, if it exceeds 100 parts by weight, the adhesive strength of the surface layer to the intermediate layer tends to decrease. A surface layer is formed by applying this liquid adhesive onto the intermediate layer and evaporating the organic solvent or water. A toner image is formed on the surface layer of the thus obtained lithographic printing plate material having a three-layer structure consisting of the base material, intermediate layer and surface layer using an electrophotographic copying machine. After the toner image is formed, a lithographic printing plate is obtained by removing the surface layer in the non-image area using an organic solvent, water, or the like. Therefore, since the intermediate layer is exposed in the non-image area and is highly hydrophilic, water adheres to the non-image area and ink adheres to the toner image, making it difficult to perform planographic printing successfully. can. (d) Examples Example 1 100 parts by weight of monomethyltrimethoxysilane was added to an organic solvent prepared by mixing 700 parts by weight of water and 700 parts by weight of isopropanol, and then the degree of saponification was 55.
After dissolving 100 parts by weight of % polyvinyl alcohol, cross-linked sodium polyacrylate (Sumitomo Chemical
Co., Ltd., product name Sumikagel) 100 parts by weight, particle size 10
100 parts by weight of silicon dioxide having a particle size of ~15 mmμ and 1 part by weight of sodium acetate were added and mixed and stirred to obtain a composition. This composition was applied to a degreased aluminum thin plate (JIS A-1100, thickness 0.15 mm, dimensions 200 mm x 300
mm) with a #6 bar coater and heated to 100°C.
was heated for 60 seconds to form an intermediate layer on the aluminum thin plate. Furthermore, a liquid adhesive having the following composition was applied onto this intermediate layer using a #6 bar coater, and dried at 100° C. for 60 seconds to obtain a lithographic printing plate material. Zinc oxide: 30 parts by weight Ethyl cellulose: 60 parts by weight Ethyl alcohol: 500 parts by weight A toner image (toner composition: carbon black as a coloring agent, polystyrene as a binder,
After forming a test pattern (175 lines, 3 to 75% halftone dots), this was immersed in ethyl alcohol for 1 minute to remove the surface layer exposed in the non-image area to obtain a lithographic printing plate. Ta. When this lithographic printing plate was printed on high-quality paper using a Heidel KORD printing machine, approximately 10,000 prints were obtained without any background smudges. Example 2 After adding 100 parts by weight of monomethyltrimethoxysilane to an organic solvent prepared by mixing 800 parts by weight of water and 500 parts by weight of methanol, and then dissolving 80 parts by weight of polyvinyl alcohol with a degree of saponification of 40%. , 90 parts by weight of a crosslinked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumikagel), 55 parts by weight of titanium oxide with a particle size of 10 to 15 mmμ, and 2 parts by weight of sodium acetate were mixed and stirred to form a composition. I got something. This composition was used in the same manner as in Example 1 to form an intermediate layer on a thin aluminum plate. Then, a liquid adhesive having the following composition was applied onto the intermediate layer under the same conditions as in Example 1, and dried to obtain a lithographic printing plate material. Lead telluride 20 parts by weight Polyvinyl acetate 40 parts by weight Acetone 500 parts by weight A toner image (toner composition: carbon black as a coloring agent, polystyrene as a binder,
After forming a test pattern (175 lines, 3 to 75% halftone dots), this was immersed in acetone for 1 minute to remove the surface layer exposed in the non-image area to obtain a lithographic printing plate. . Example 1 was carried out using this lithographic printing plate material.
When printing under the same conditions as above, we were able to obtain approximately 10,000 prints without any background smudges. Example 3 Example 3 100 parts by weight of γ-glycidoxypropyltrimethoxysilane was added to an organic solvent prepared by mixing 400 parts by weight of water and 1000 parts by weight of isopropanol, and then polyvinyl alcohol with a degree of saponification of 50% was added.
After dissolving 100 parts by weight of sodium polyacrylate, 50 parts by weight of a crosslinked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumikagel) and barium sulfate with a particle size of 10 to 15 mmμ.
30 parts by weight and 1 part by weight of sodium acetate were added, mixed and stirred to obtain a composition. This composition was used in the same manner as in Example 1 to form an intermediate layer on a thin aluminum plate. Then, a liquid adhesive having the following composition was applied onto the intermediate layer under the same conditions as in Example 1, and dried to obtain a lithographic printing plate material. Polyvinyl carbazole 25 parts by weight Crystal violet (sensitizer) 1 part by weight Ethyl cellulose 40 parts by weight Ethyl alcohol 350 parts by weight A toner image (toner composition: carbon as a coloring agent) is printed on the surface of this lithographic printing plate material using an electrophotographic copying machine. black, polystyrene as binder,
After forming a test pattern (175 lines, 3 to 75% halftone dots), this was immersed in ethyl alcohol for 1 minute to remove the surface layer exposed in the non-image area to obtain a lithographic printing plate. Ta. When printing was carried out using this lithographic printing plate material under the same conditions as in Example 1, about 10,000 prints could be obtained without occurrence of scumming or the like. (E) Effects of the Invention The lithographic printing plate material obtained by the method of the present invention has a three-layer structure of a base material, an intermediate layer, and a surface layer. The intermediate layer is obtained by coating a specific composition and is hydrophilic, and the surface layer is obtained by coating a liquid adhesive containing a photoconductive substance and has good toner receptivity. Therefore, after forming a toner image on the surface layer, by removing the surface layer in the non-image area with an organic solvent or the like, the intermediate layer is exposed in the non-image area and the non-image area becomes hydrophilic. Of course, it goes without saying that the organic solvent used to remove the non-image area must not have an adverse effect on the toner image area. In the planographic printing plate thus obtained, water adheres to the non-image areas and ink adheres to the toner image areas, allowing good planographic printing. As is clear from the above explanation, the lithographic printing plate material obtained by the method of the present invention can be prepared by the process of selectively applying a hydrophilic treatment agent to non-image areas, as in the conventional lithographic printing plate material (master paper). is no longer necessary, and a lithographic printing plate can be easily obtained by simply immersing the toner in an organic solvent or the like after forming a toner image to remove the surface layer of the non-image area (this can also be referred to as development treatment with an organic solvent or the like). This effect is achieved.

[Claims]

1 In an organic solvent, (a) General formula (); CH ₂ = CXCOO (CH ₂ )nSi(OH) ₃ () (wherein, X represents a hydrogen atom or a methyl group,
n represents an integer of 1 to 6. ) A trihydroxysilane compound represented by (b) a polymerization catalyst for the trihydroxysilane compound, (c) polyvinyl alcohol with a saponification degree of 30 to 60%, and (d) a crosslinked product of an alkali salt of polyacrylic acid. , (e) A liquid adhesive in which an inorganic powder insoluble in an organic solvent and a composition formed by dissolving or dispersing the following are applied to a base material, dried to form an intermediate layer, and then a photoconductive substance is dispersed. 1. A method for producing a lithographic printing plate material, which comprises applying an agent to the intermediate layer and then drying it to form a surface layer.