JPH0473397B2 - - Google Patents

Description

Detailed Description of the Invention (a) Field of Industrial Application 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 particularly, 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 for a lithographic printing plate. 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 the conventional technology and the invention Conventionally, the surface of the support of a lithographic printing plate has been subjected to graining treatment to improve adhesion to the photosensitive resin, or to improve hydrophilicity. Various treatments, such as immersion treatment in a silicate solution or the like, have been carried out.

However, performing these various treatments may cause problems with quality stability, quality control,
The disadvantage is 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 proposed an invention related to Japanese Patent Application No. 59-233845. In this prior invention, 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 is applied to the surface of a substrate.
The aim is to improve the hydrophilicity of the support surface and the adhesion to the photosensitive resin without performing various treatments as in the past.

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

(c) Means and effects for solving the problems That is, the present invention provides a water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, and a chelate compound that is coordinated with the polyvinyl alcohol. The present invention relates to an aqueous solution composition for forming a support surface layer of a lithographic printing plate, which contains a metal compound, a water-insoluble inorganic powder, and an ethylenediamine derivative represented by the following general formula ().

General formula (); (In the formula, x and y represent positive integers of 2 to 10.) The water-soluble melamine resin used in the present invention is a commercially available monomer resin or a multimer resin such as a dimer type resin with a certain degree of polycondensation. Any resin may be used. 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 metal 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 a metal compound that is coordinated to the polyvinyl alcohol to form a chelate compound. Zirconium nitrate is generally used as this metal compound, but other zirconium salts can also be used. Polyvinyl alcohol mainly improves the hydrophilicity of the surface layer of the support.

The water-insoluble inorganic powder used in the present invention includes:
Any substance that is insoluble or has extremely low solubility in water may be used, such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, lead oxide, bismuth oxide, bismuth oxide, etc. Metal or nonmetal oxides such as magnesium and manganese oxide, calcium carbonate,
Examples include salts such as calcium sulfate, silicon compounds such as silicon dioxide, natural pigments such as kaolin, bentonite, and clay, and various metal powders such as aluminum, iron, and zinc. Among these inorganic powders,
Particularly suitable is silicon dioxide, which has excellent hydrophilicity and is hydrated and dispersed in water as a colloid (colloidal silica). When the water-insoluble inorganic powder is present in the surface layer of the support, it forms fine irregularities on the surface. In addition, the particle size of the inorganic powder should be about 320 mesh pass,
The smaller the particle size, the more suitable it is for use in the present invention.

The ethylenediamine derivative represented by the general formula () used in the present invention (hereinafter simply referred to as "ethylenediamine derivative") is a substance obtained by adding propylene oxide to ethylenediamine and then adding ethylene oxide. The number of moles of propylene oxide and ethylene oxide added is 8 to 40 moles. If the number of moles of propylene oxide and ethylene oxide added is less than 8 moles, the degree of hydrophilicity is undesirably low. Furthermore, if the number of moles added exceeds 40 moles, the substance itself becomes too viscous, making it unfavorable for handling. Ethylenediamine 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, a solution A is prepared by dissolving, for example, polyvinyl alcohol and a metal compound such as zirconium nitrate that is coordinated with the polyvinyl alcohol to form a chelate compound in water. Separately from liquid A, a water-soluble melamine resin and its curing catalyst are dissolved in water to obtain liquid B. Next, liquids A and B are mixed, water-insoluble inorganic powder and ethylenediamine derivative, and if necessary, chelating agents, pigments, dyes, thickeners, etc. are added, and strong stirring is performed to remove the liquid. Just make bubbles.

The quantitative ratio of each component in the composition according to the present invention is approximately 50 to 200 parts by weight, preferably 80 to 180 parts by weight, of polyvinyl alcohol per 100 parts by weight of the water-soluble melamine resin. 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 the metal compound that is coordinated with polyvinyl alcohol to form a chelate compound is about 2 to 10 parts by weight per 100 parts by weight of polyvinyl alcohol.
Preferably it is about 4 to 7 parts by weight. If the amount of the metal compound 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, and is, for example, about 0.1 to 5 parts by weight per 100 parts by weight of the water-soluble melamine resin.

The amount of water-insoluble inorganic powder is the amount of water-soluble melamine resin
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 water-insoluble inorganic powder is less than 30 parts by weight, irregularities on the surface of the support tend to vary, resulting in poor halftone dot reproducibility in the image area. Also, if it exceeds 150 parts by weight,
The amount of permeation of the photosensitive liquid into the support increases, resulting in an increase in the amount of photosensitive liquid used, which tends to be uneconomical.

The amount of the ethylenediamine derivative is about 30 to 150 parts by weight, preferably about 50 to 100 parts by weight, based on 100 parts by weight of the water-soluble melamine resin. If the amount of the ethylenediamine derivative is less than 30 parts by weight, the ability to retain a water film on the surface of the support tends to decrease, and if it exceeds 150 parts by weight, the ability to retain a water film tends not to increase, making it 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, 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 First, an aqueous solution composition having the composition shown below was prepared.

Water-soluble melamine resin 100 parts by weight Guanidine sulfamate 0.5 parts by weight Polyvinyl alcohol 100 parts by weight Zirconium nitrate 6 parts by weight Silicon dioxide 100 parts by weight Aqueous solution concentration 20% by weight This composition was applied to a degreased aluminum thin plate (JIS A-1100, thickness 0.15mm, dimensions 200mm
mm) with a #6 bar coater at 180°C.
The mixture was dried for 3 minutes in a hot air dryer to obtain a support for a lithographic printing plate. A negative photosensitive resin liquid was applied to the surface of this support, dried for 1 minute in a hot air dryer at 120°C, and then a negative film (test pattern: 175 lines, halftone dots 3-75%) was applied on the coated surface. This was overlapped and exposed for 30 seconds from a distance of 1 m using an ultra-high pressure mercury lamp (electrical capacity 4 kW). Thereafter, it was resolved using a developer to obtain a lithographic printing plate.

In order to evaluate the dampening water retention of this lithographic 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 while supplying printing ink. As a result, in Example 1, 12 proof sheets could be obtained.

Example 2 A lithographic printing plate was obtained under the same conditions as in Example 1 except that the following aqueous solution composition was used, and its performance test was conducted.

Water-soluble melamine resin 100 parts by weight Ammonium chloride 0.7 parts by weight Polyvinyl alcohol 77 parts by weight Zirconium nitrate 4 parts by weight Titanium oxide 55 parts by weight Aqueous solution concentration: 15% by weight As a result, in Example 2, 10 proof sheets could be obtained.

Example 3 A lithographic printing plate was obtained under the same conditions as in Example 1 except that the following aqueous solution composition was used, and its performance test was conducted.

Water-soluble melamine resin 100 parts by weight Methylaniline 2 parts by weight Polyvinyl alcohol 67 parts by weight Zirconium nitrate 3 parts by weight Barium sulfate 30 parts by weight Aqueous solution concentration: 13% by weight As a result, in Example 3, 12 proof sheets could be obtained.

Comparative Example A lithographic printing plate was obtained under the same conditions as in Example 1, except that the following aqueous solution composition was used, and its performance test was conducted.

Water-soluble melamine resin 100 parts by weight Guanidine sulfamate 0.5 parts by weight Polyvinyl alcohol 100 parts by weight Zirconium nitrate 6 parts by weight Silicon dioxide 100 parts by weight Aqueous solution concentration 20% by weight As a result, in the comparative example, 5 proof sheets were obtained.6 Printing stains became noticeable from the first sheet onwards.

As is clear from the above results, when the lithographic printing plate support according to the example is used, the water film retention in the non-image area is approximately twice as high as that of the lithographic printing plate support according to the comparative example. It turns out to be 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 superior to the invention of Japanese Patent Application No. 59-233845, which is the earlier invention. Ethylenediamine derivatives with excellent water film retention properties are blended into the surface layer. Therefore, when used as a lithographic printing plate, the water film formed on non-image areas by supplying dampening water is well retained during printing and is less likely to be disturbed, reducing the chance of staining the 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.

Moreover, if the aqueous solution composition according to the present invention is used,
A lithographic printing plate support having a surface layer with excellent hydrophilicity and excellent adhesion to a photosensitive resin can be obtained simply by coating the surface of the substrate. Therefore, it also has the effect of eliminating the need for conventional graining treatments, hydrophilization treatments, etc.

Claims (1)

[Scope of Claims] 1. A water-soluble melamine resin, a curing catalyst for the water-soluble melamine resin, polyvinyl alcohol, a metal compound that is coordinated to the polyvinyl alcohol to produce a chelate compound, and a water-insoluble inorganic powder;
An aqueous solution composition for forming a surface layer on a support of a lithographic printing plate, comprising: an ethylenediamine derivative represented by the following general formula (). General formula (); (In the formula, x and y represent positive integers from 2 to 10.)