JPS62138293A - Aqueous solution composite for formation of support surface of lithoprinting plate - Google Patents

Abstract

PURPOSE:To improve the durability of an aqueous film on the surface of a wetting water support by containing water-soluble melamine resin, a curing catalyst for water-soluble melamine resin, polyvinyl alcohol, zirconium nitrate, water-insoluble inorganic powder and phytic acid. CONSTITUTION:This invention is an aqueous solution composite for formation of a support surface layer of a lithoprinting plate contains water-soluble melamine resin, curing catalyst for water-soluble melamine resin, plyvinyl alcohol, zirconium nitrate, water-insoluble inorganic powder and phytic acid. As water-soluble melamine resin, either the monomer resin or the polymer resin such as dimer-type resin condensation-polymerized to some degree may be used. As a curing catalyst for water-soluble melamine resin, organic amine salt catalyst is preferred. The desirable type of polyvinyl alcohol is a perfect again type. The recommendable water-insoluble inorganic powder is silicon bioxide which is highly hydrophilic and hydrated/dispersed in water in colloidal form. Phytic acid contributes to the formation and maintenance of an aqueous film by wetting water on the surface of the support.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to an aqueous solution composition for forming a surface layer of a support for a lithographic printing plate, and more specifically, it relates to an aqueous solution composition for forming a surface layer of a support for a lithographic printing plate, and more specifically, it relates to an aqueous solution composition for forming a surface layer of a support on the surface of a support. The present invention relates to an aqueous solution composition that is applied to the surface of a base material to form a surface layer in order to provide adhesiveness and adhesion to a photosensitive resin.

(b) Problems to be solved by conventional techniques and inventions Conventionally, the surface of the support of lithographic printing plates has been subjected to graining treatment to improve adhesion to photosensitive resins, or to have hydrophilic properties. Various treatments such as immersion treatment in silicate solution etc. have been carried out to improve the quality.

However, performing these various treatments may cause problems with quality stability or quality control.

This has the drawback that the equipment and maintenance require constant integrity, resulting in expensive supports for lithographic printing plates.

In order to solve the above-mentioned drawbacks, the present inventor previously filed a patent application filed in 1983-
Tsutsumi proposed the invention related to No. 233845. This prior invention can be applied to the surface of a substrate by applying a composition in the form of an aqueous solution consisting of polyvinyl alcohol, zirconium nitrate, a water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, and a water-insoluble inorganic powder. The aim is to improve the hydrophilicity of the support surface and the adhesion to the photosensitive resin without performing any other treatment.

The present invention is a further improvement of the above-mentioned prior invention,
This further improves the ability of dampening solution to retain a water film on the surface of the support.

(c) Means and action for solving the problems, that is, the present invention comprises a water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, zirconium nitrate, a water-insoluble inorganic powder, and phytic acid. The present invention relates to an aqueous solution composition for forming a surface layer of a support of a lithographic printing plate, characterized by containing the following.

The water-soluble melamine resin used in the present invention may be either a commercially available monomer resin or a multimer resin such as a dimer type resin with a certain degree of polycondensation. Examples of curing catalysts for water-soluble melamine resins include ammonium salt catalysts such as ammonium chloride, diammonium phosphate, and ammonium sulfamate, hydrochloric acid or sulfamate salts of organic amino alcohols, dimethylaniline hydrochloride, pyridine-based catalysts, etc.
Examples include hydrochloric acid catalysts, organic amine salt catalysts such as picoline-monochloroacetic acid, and inorganic gold mud catalysts such as magnesium chloride, zinc chloride, and zinc sulfate.

Among them, it is preferable to use an organic amine salt catalyst. The water-soluble melamine resin becomes a three-dimensional network polymer by its curing catalyst, and becomes the base of the surface layer of the support.

As the polyvinyl alcohol used in the present invention, any commercially available completely saponified type, intermediate saponified type, or partially saponified type can be used, but the completely saponified type is used for the purpose of manufacturing with good reproducibility of performance as a support in printing. It is preferable. Polyvinyl alcohol is insolubilized by zirconium nitrate. Polyvinyl alcohol mainly improves the hydrophilicity of the surface layer of the support.

The water-insoluble inorganic powder used in the present invention may be one that is insoluble in water or has extremely low solubility, such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, tin oxide, r! Metal or non-metal oxides such as titanium iron chloride, copper oxide, lead oxide, hismuth oxide, magnesium oxide, manganese oxide, calcium carbonate.

Salts such as calcium sulfate, silicon compounds such as silicon dioxide,
Examples include natural pigments such as kaolin, bentonite, and clay, and various metal powders such as aluminum, iron, and zinc. Among these inorganic powders, silicon dioxide, which has excellent hydrophilicity and is hydrated to form a colloid (colloidal silica) and disperse in water, is particularly suitable. When the water-insoluble inorganic powder is present in the surface layer of the support, 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 suitable it is for use in the present invention.

Phytic acid used in the present invention is also called inosit hexalinic acid, and is a compound that is a viscous liquid, easily soluble in water, and has a high affinity for water. Phytic acid helps the dampening solution form and maintain a water film on the surface of the support.

In preparing the composition according to the present invention, for example, polyvinyl alcohol and zirconium nitrate are dissolved in water to prepare a solution A. Separately from liquid A, a water-soluble melamine resin and its curing catalyst are dissolved in water to obtain liquid B. Next, liquid A and liquid B are mixed, and water-insoluble inorganic acid) and phytic acid are mixed therein.
Further, if necessary, chelating agents, pigments, dyes, thickeners, etc. may be added and vigorous stirring may be performed to defoam.

The quantitative ratio of each component in the composition according to the present invention is about 50 to 200 parts by weight, preferably 80 to 180 parts by weight of polyvinyl alcohol to 100 parts by weight of water-soluble melamine resin.
The weight part is normal. If polyvinyl alcohol is less than 50 parts by weight, the surface layer tends to lack hydrophilicity,
If the amount exceeds 200 parts by weight, the surface layer may melt and cause printing stains.

The amount of zirconium nitrate is 100% polyvinyl alcohol
About 2 to 10 parts by weight, preferably 4 to 7 parts by weight
It is a weight section. If the amount of zirconium nitrate is less than 2 parts by weight, the insolubilization of polyvinyl alcohol tends to be incomplete, and if it exceeds 10 parts by weight, when the composition according to the present invention is used as a surface layer of a support, non-image areas may be The surface of the formed support lacks hydration and accepts printing ink, which tends to cause so-called scumming on the plate surface. Also,
The amount of the curing catalyst for the water-soluble melamine resin may be sufficient to cure the water-soluble melamine resin (for example, 0.1 to 5 parts by weight per 100 parts by weight of the water-soluble melamine resin). be.

The amount of insoluble inorganic powder in 7 is 100% of the water-soluble melamine resin.
Approximately 30 to 150 parts by weight, or 5 parts by weight
The amount is about 0 to 120M parts. If the amount of the water-insoluble inorganic powder is less than 30 parts by weight, irregularities on the surface of the support tend to vary, leading to poor halftone dot reproducibility in the image area. If the amount exceeds 150 parts by weight, the amount of photosensitive liquid that permeates into the support increases, resulting in an increase in the amount of photosensitive liquid used, which becomes uneconomical.

The amount of phytic acid is about 50 to 200 parts by weight, or 80 to 15 parts by weight per 100 parts by weight of the water-soluble melamine resin.
Place around 0 parts by weight. If the amount of phytic acid is less than 50 parts by weight, the ability to retain a water film on the surface of the support tends to decrease, and if it exceeds 200 parts by weight, the ability to retain a water film tends not to increase, which becomes uneconomical. Tend.

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 + i; I+ Foil or plate made of metals such as zinc and lead or alloys thereof, plastics such as polyester, polypropylene, polyimide, polyacrylonitrile, polycarbonate, polyamide, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, etc. Molded products in film or sheet form, synthetic paper, art paper.

Various materials such as coated paper, cardboard, thin paper, etc. can be used. Metal base materials include aluminum, zinc,
Iron etc. are suitable. 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 and ethylenediaminetetraacetic acid for the purpose of increasing adhesive strength with the base material.

trans-cyclohexane-1,2-diaminetetraacetic acid, butane-1,2,3,4-tetracarboxylic acid, propylenediaminetetraacetic acid, pentamethylenecyaminetetraacetic acid, cyclopenkune-1,2-diaminetetraacetic acid M, cyclohexane A chelating agent such as -1,4-diaminetetraacetic acid or 2-hydroxytrimethylenediaminetetraacetic acid may be added to the composition according to the present invention. Furthermore, the substrate does not need to be particularly 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 First, each aqueous solution composition having the composition shown in Table 1 was prepared.

Each of these compositions was applied to a degreased aluminum thin plate (J
IS A-1100, thickness 0.15in, dimension 200w
x300mm) with a #6 bar coater,
Four types of lithographic printing plate supports were obtained by drying in a hot air dryer at 80°C in Table 1 for 3 minutes. A negative photosensitive resin liquid was applied to the surface of each support, and after drying for 1 minute in a hot air dryer at 120°C, a negative film (test pattern; I7
5 lines, halftone dots 3 to 75%) were overlapped and exposed for 30 seconds from a distance of 1 m using an ultra-high pressure mercury lamp (electrical capacity 4 KW). Thereafter, resolution was performed using a developer to obtain four types of lithographic printing plates.

In order to evaluate the dampening water retention of each planographic printing plate, it was tested by the following method. First, dampening water was supplied to the lithographic printing plate to form a water film on the non-image area.

Thereafter, the supply of dampening water was cut off, and proof printing was performed under the same conditions while supplying printing ink. As a result, Examples 1-
3, it was possible to obtain 8 proof sheets, but in the comparative example, 5 proof sheets were obtained, and printing stains became noticeable from the 6th sheet onward. As is clear from this, when the lithographic printing plate support according to the example is used, the water film retention in the non-image area is about 1.5 times higher than that of the lithographic printing plate support according to the comparative example. It turns out that it is excellent.

(e) Effects of the invention The support for a lithographic printing plate obtained by applying the aqueous solution composition of the present invention to a base material is an earlier invention of Japanese Patent Application No. 59-23
In contrast to the No. 3845 invention, phytic acid, which has excellent water film retention properties, is blended into the surface layer of the support. Therefore, when used as a lithographic printing plate, the water film formed on non-image areas by supplying dampening water is well maintained during printing and is less likely to be disturbed, reducing the chance of staining printed matter. . Furthermore, since the water film retention property is good, there is also an effect that the amount of dampening water supplied can be reduced.

Furthermore, by using the aqueous solution composition according to the present invention, a support for a flat or shadow printing plate having a surface layer with excellent hydrophilicity and excellent adhesion to a photosensitive resin can be obtained by simply coating the surface of the base material. can be obtained. Therefore, the conventional graining process 1w1. Characterized by the effect of eliminating the need for water treatment, etc.

Claims (1)

[Claims] A water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, and zirconium nitrate,
An aqueous solution composition for forming a surface layer on a support of a lithographic printing plate, comprising a water-insoluble inorganic powder and phytic acid.