JPH0529104B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a composition for forming a surface layer of a lithographic printing plate material suitable for use in electrophotolithography, and more specifically, it relates to a composition that has hydrophilic and The present invention relates to a composition that is applied to the surface of a substrate to form a surface layer so as to have water film retention properties and form an electrostatic latent image. (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, and it forms an electrostatic latent image on a zinc oxide photoconductive layer, and then attaches lipophilic developing powder (toner) to the electrostatic latent image to form an image area. to form a lithographic printing plate. By the way, since the zinc oxide 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. It is done by applying it to the 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 inventors of the present invention conducted intensive studies to obtain a lithographic printing plate material that does not require hydrophilic treatment of non-image areas after the formation of image areas. The inventors have discovered that a lithographic printing plate material having both properties and photoconductivity can be obtained, leading to the present invention. (d) Means and effects for solving the problems That is, the present invention relates to a composition for coating on a base material of a lithographic printing plate material, in which (a) general formula (); CH ₂ = CXCOO(CH ₂ ) _o Si(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. The present invention relates to a composition for forming a surface layer of a lithographic printing plate material, characterized in that it is formed by dissolving or dispersing (e) a photoconductive substance; The component (a) used in the present invention has the general formula ()
It is a trihydroxysilane compound represented by
Specific examples of trihydroxysilane compounds include:
Examples include γ-methacryloxypropyltrihydroxysilane and γ-acryloxypropyltrihydroxysilane. Component (b) used in the present invention is a polymerization catalyst for a trihydroxysilane compound. Specific examples of this polymerization catalyst include sodium acetate, sodium thiocyanate, triethylenetetramine, trimethylbenzylammonium hydroxide, 1,8-diazabicyclo(5,4,
0) Undecene-7 or its acetate, amine compounds and the like. A trihydroxysilane compound becomes a three-dimensional network polymer having an (O--Si--O) structure as a skeleton by its polymerization catalyst, and becomes the base of the surface layer of a printing plate material. The component (c) used in the present invention has a saponification degree of 30 to 60.
% polyvinyl alcohol. Saponification degree is 60%
If it exceeds 30%, it becomes insoluble in organic solvents, which is not preferable, and if it is less than 30%, the degree of hydrophilicity is low, which is not preferable. Polyvinyl alcohol mainly improves the hydrophilicity of the surface layer of printing plate materials. Component (2) used in the present invention is a crosslinked product of 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. As a crosslinking agent, diglycidyl ether compounds such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin diglycidyl ether, epichlorohydrin, epibromohydrin,
Haloepoxy compounds such as α-methylepichlorohydrin, aldehyde compounds such as glutaraldehyde and glyoxal, and isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate are used. The crosslinked polyacrylic acid alkali salt improves the hydrophilicity of the surface layer of the printing plate material and also improves the retention of dampening water. The photoconductive substances used as component (e) in the present invention include powdered zinc oxide, silicon, germanium, arsenic, tellurium, selenium, gallium arsenide, cadmium sulfide, cadmium selenide, lead sulfide, and lead telluride. , gallium arsenide, selenium-tellurium mixed crystal,
Inorganic substances such as 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, trinitrofluorenone, triallylcarbonium salt, benzopyrylium salt,
It is common to use a sensitizer such as crystal violet in combination. This photoconductive substance imparts photoconductivity to the surface layer of the printing plate material and enables the formation of an electrostatic latent image. The composition according to the present invention can be obtained by uniformly dissolving or dispersing the above-mentioned components (a) to (e) in an organic solvent. Examples of organic solvents include methyl alcohol,
Ethyl alcohol, isopropyl alcohol, butyl alcohol, acetic acid, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethyl cellosolve, butyl cellosolve, cello acetate, toluene, xylene, trichloroethylene, chloroform, etc. are used alone or in combination. In the present invention, it is preferable to add an inorganic powder insoluble in the organic solvent as necessary. Inorganic powders that are insoluble in organic solvents may be those that are insoluble in organic solvents or have extremely low solubility, such as zinc oxide, aluminum oxide, antimony oxide,
Metal or nonmetal oxides such as calcium oxide, 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 dioxide, etc. Examples include silicon compounds, natural pigments such as kaolin, bentonite, and clay, and various metal powders such as aluminum, iron, and zinc. When an inorganic powder insoluble in an organic solvent is present in the surface layer of a printing plate material, it forms fine irregularities on the surface. 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. When preparing the composition according to the present invention, for example, the trihydroxysilane compound as the component (a) and the trihydroxysilane compound as the component (b)
After dissolving the polymerization catalyst of the trihydroxysilane compound as the component and polyvinyl alcohol with a degree of saponification of 30 to 60% as the component (iii) in an organic solvent, the crosslinked product of the alkali salt of polyacrylic acid as the component (d) and ( E) component photoconductive substance is added, and if necessary, an inorganic powder insoluble in an organic solvent, a chelating agent, a pigment, a dye, a thickener, etc. are added, and the bubbles are defoamed by vigorous stirring. . The quantitative proportions of each component in the composition according to the present invention are preferably as follows. That is, the amount of the polymerization catalyst for the trihydroxysilane compound may be sufficient as long as it is sufficient to polymerize the trihydroxysilane compound, and is usually about 0.1 to 5 parts by weight per 100 parts by weight of the trihydroxysilane compound. The amount of polyvinyl alcohol is about 50 to 200 parts by weight, more preferably about 80 to 180 parts by weight, per 100 parts by weight of the trihydroxysilane compound. If the amount of polyvinyl alcohol is less than 50 parts by weight, the surface layer tends to lack hydrophilicity, and if it exceeds 200 parts by weight, the surface layer may melt and cause printing stains. The amount of crosslinked polyacrylic acid alkali salt is
For 100 parts by weight of trihydroxysilane compound
The amount is about 50 to 200 parts by weight, more preferably about 80 to 150 parts by weight. The amount of polyacrylic acid alkali salt
If it is less than 50 parts by weight, the ability to retain dampening water on the surface of the printing plate material will decrease and the hydrophilicity will tend to decrease, and if it exceeds 200 parts by weight, the ability to retain dampening water will not tend to increase. It tends to be uneconomical. The amount of the photoconductive substance is about 5 to 50 parts by weight, preferably about 10 to 30 parts by weight, based on 100 parts by weight of the trihydroxysilane compound. 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 printing plate material. Also,
If it exceeds 50 parts by weight, the amount of polyvinyl alcohol or polyacrylic acid alkali salt tends to decrease relatively, and the hydrophilicity tends to decrease. In addition, the amount of inorganic powder insoluble in organic solvents to be added as necessary is determined by the amount of trihydroxysilane compound
The amount is about 30 to 150 parts by weight, preferably about 50 to 120 parts by weight, per 100 parts by weight. If the amount of the inorganic powder insoluble in the organic solvent is less than 30 parts by weight, variations in the unevenness of the surface of the printing plate material tend to occur, and the adhesion of the developing powder forming the image area tends to vary as well. Further, even if the amount exceeds 150 parts by weight, the adhesion of the developing powder cannot be improved much, and adding more than this tends to be uneconomical. As the base material for applying the composition according to 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 films or sheet-like molded products made of polyester, polypropylene, polyimide, polyacrylonitrile, polycarbonate, polyamide, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, etc. , synthetic paper, art paper,
Various materials such as coated paper, cardboard, thin paper, etc. 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 according to the present invention to a metal substrate, 5%
-Sulfosalicylic acid, ethylenediaminetetraacetic acid, trans-cyclohexane-1,2-diaminetetraacetic acid, butane-1,2,3,4-tetracarboxylic acid, propylenediaminetetraacetic acid, pentamethylenediaminetetraacetic acid, cyclopentane-1, Chelating agents such as 2-diaminetetraacetic acid, cyclohexane-1,4-diaminetetraacetic acid, and 2-hydroxytrimethylenediaminetetraacetic acid may be added to the composition according to the present invention. Furthermore, the substrate does not need to be pretreated prior to application of the composition according to the invention, as long as its surface is not 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. (d) Examples Example 1 100 parts by weight of γ-methacryloxypropyltrihydroxysilane and trimethylbenzyl were added to an organic solvent prepared by mixing 450 parts by weight of ethyl acetate, 600 parts by weight of ethyl alcohol, and 450 parts by weight of methyl isobutyl ketone. After dissolving 2 parts by weight of ammonium hydroxide and 100 parts by weight of polyvinyl alcohol with a degree of saponification of 55%, 100 parts by weight of a crosslinked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumikagel) and zinc oxide. 20 parts by weight, and particle size 10-15mm
100 parts by weight of silicon dioxide of μ was 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 at 230°C.
was heated for 60 seconds to form a surface layer (surface film), and a lithographic printing plate material was obtained. A toner image (test pattern: 175 lines, halftone dots 3 to 75%) was formed on the surface of this lithographic printing plate material using an electrophotographic copying machine to obtain a lithographic printing plate. 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 2 100 parts by weight of γ-methacryloxypropyltrihydroxysilane, 3 parts by weight of trimethylbenzylammonium, and saponification degree
After dissolving 80 parts by weight of 40% polyvinyl alcohol, a crosslinked product of sodium polyacrylate (Sumitomo Chemical
90 parts by weight of Sumikagel (trade name) manufactured by Co., Ltd., 30 parts by weight of lead telluride, and 55 parts by weight of titanium oxide having a particle size of 10 to 15 mmμ were added and mixed and stirred to obtain a composition. This composition was used in the same manner as in Example 1 to obtain a lithographic printing plate. Example 1 using this lithographic printing plate
When printing was carried out in the same manner as in Example 2, about 10,000 prints were obtained without any occurrence of scumming or the like. Example 3 100 parts by weight of γ-acryloxypropyltrihydroxysilane was added to an organic solvent prepared by mixing 400 parts by weight of ethyl acetate, 600 parts by weight of ethyl alcohol, 450 parts by weight of methyl isobutyl ketone, and 100 parts by weight of cellosolve acetate. After dissolving 2 parts by weight of trimethylbenzylammonium hydroxide and 100 parts by weight of polyvinyl alcohol with a degree of saponification of 50%,
Crosslinked product of sodium polyacrylate (manufactured by Sumitomo Chemical Co., Ltd.,
50 parts by weight of Sumikagel (trade name), 15 parts by weight of polyvinyl carbazole, 1 part by weight of crystal violet as a sensitizer, and 30 parts by weight of barium sulfate with a particle size of 10 to 15 mmμ are mixed and stirred to form a composition. I got it. This composition was used in the same manner as in Example 1 to obtain a lithographic printing plate. Example 1 using this lithographic printing plate
When printing was carried out in the same manner as in Example 3, about 10,000 prints were obtained without any occurrence of scumming or the like. Comparative Example 100 parts by weight of γ-methacryloxypropyltrihydroxysilane and 2 parts by weight of trimethylbenzylammonium hydroxide were added to an organic solvent prepared by mixing 450 parts by weight of ethyl acetate, 600 parts by weight of ethyl alcohol, and 450 parts by weight of methyl isobutyl ketone. After dissolving 30 parts by weight of zinc oxide and 100 parts by weight of silicon dioxide having a particle size of 10 to 15 mmμ,
A composition was obtained by mixing and stirring. This composition was used in the same manner as in Example 1 to obtain a lithographic printing plate. When printing was carried out using this lithographic printing plate in the same manner as in Example 1, in the comparative example, background smear occurred from the start of printing, and from about the 200th sheet onwards, the background smear became noticeable and printing could not be continued. Ta. As is clear from the above results, by using the lithographic printing plate material according to the example, more printed matter with less scumming can be obtained compared to the lithographic printing plate material according to the comparative example. (e) Effects of the invention The lithographic printing plate material obtained by applying the composition according to the present invention to a substrate has a surface layer that is different from that of the conventional lithographic printing plate material (master paper). Since it has been made hydrophilic in advance and has improved water film retention in non-image areas, printing with this material can produce printed matter with less scumming. Further, when an inorganic powder insoluble in an organic solvent is added to the composition of the present invention, fine irregularities are formed on the surface of the lithographic printing plate material, and the image area formed by the toner adheres to the printing plate material. It has the effect of improving sexual performance.

[Claims]

1 General formula below [In the formula, R ₁ represents a phenyl group and R ₂ represents a benzyl group, R ₁ represents a phenyl group and R ₂ represents a methyl group, or R ₁ and R ₂ represent a methyl group. represent ] An organic semiconductor represented by 2. In an electrophotographic photoreceptor in which a photosensitive layer is formed on a substrate, the following general formula is used as a charge transport material for the photosensitive layer.