JPS61112150A - Composition for forming lithographic printing base layer - Google Patents

Abstract

PURPOSE:To obtain a paint for forming a lithographic printing base layer which is simply coated once on a base material and does not require surface polishing, etc. by dispersing water-insoluble inorg. powder into an aq. soln. consisting of PVA, zirconium nitrate, water soluble melamine resin and curing catalyst. CONSTITUTION:A soln. prepd. by adding guanidine sulfamate as the curing catalyst to an aq. water soluble melamine resin soln. is mixed with an aq. soln. of 5% PVA and 0.05-0.5 zirconium nitrate. The pulverous water-insoluble powder such as colloidal silica is dispersed into such soln. mixture by which the paint for forming the lithographic printing base layer is obtd. The paint is coated onto the degreased surface of a thin sheet of Al, etc. directly or after wet or dry polishing and is dried by hot wind. A photosensitive resin liquid is thereafter coated on the surface and is developed after exposure. The compsn. which has the high adhesive strength to a metallic base body and image layer, provides a smooth surface and is required to be coated once without the need for surface polishing, etc. is thus obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an improved composition for forming a lithographic printing support layer, and more specifically, the present invention relates to an improved composition for forming a lithographic printing support layer. The present invention relates to a composition for applying a layer that simultaneously satisfies adhesion.

[Conventional technology]

Lithographic printing is originally a printing method that takes advantage of the repellency of water and oil on the plate surface, and is broadly divided into a support layer and a photoresist layer on the surface thereof. Among these, aluminum plates have conventionally been widely used as the support layer, but they have been subjected to various processing and treatments in order to satisfy the required performance as a printing plate. That is, in order to provide image adhesion, the aluminum surface is chemically and mechanically polished to form fine irregularities (shaping treatment), then anodized to make the surface less susceptible to scratches, and then anodized. It undergoes numerous treatment steps, including treatment with a silicate solution to increase its hydrophilicity.

[Problem that the invention seeks to solve]

Performing such a large number of processes may lead to problems with quality stability and require constant perfection in quality control, equipment, and maintenance, resulting in a large cost increase for lithographic printing plate products. There was a drawback.

Furthermore, it is no exaggeration to say that there is no effective means for obtaining a support when a plastic film, sheet, paper, etc. is used as another base material.

In order to eliminate such drawbacks, the present inventors have developed a support that can completely satisfy the performance requirements of a lithographic printing support by simply providing a single layer on the surface of any base material through a single treatment. The present invention was achieved as a result of intensive research for development.

[Means for solving the problems] and [action] That is, the present invention provides an aqueous solution comprising polyvinyl alcohol, zirconium nitrate, a water-soluble melamine resin, and a curing catalyst thereof, and a water-insoluble inorganic powder dispersed in the aqueous solution. A composition for forming a lithographic printing support layer is provided.

As the polyvinyl alcohol of the present invention, commercially available fully saponified type, intermediately saponified type, and partially saponified type can all be used, but for the purpose of producing the polyvinyl alcohol with good reproducibility as a support in printing, it is preferable to use fully saponified type. is preferred.

The water-soluble melamine resin of the present invention may be either a commercially available monomer resin or a dimer type resin with an advanced degree of condensation polymerization.

Curing catalysts for melamine resin 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-hydrochloric acid, picoline-monochloroacetic acid, etc. Examples include organic amine salt catalysts such as , 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-insoluble inorganic powder in the present invention may be any powder that is insoluble in water or has extremely low solubility and has hydrophilic properties, such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, Metals and non-metal oxides such as tin, titanium oxide, iron oxide, copper oxide, lead oxide, bismuth oxide, magnesium oxide, manganese oxide,
Examples include salts such as calcium carbonate and calcium sulfate, silicon compounds such as colloidal silica, natural pigments such as kaolin, bentonite, and clay, and various metal powders such as aluminum, iron, and zinc. Among these inorganic powders, colloidal silica is particularly suitable.

In preparing the composition of 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, mix A and B solutions, add water-insoluble inorganic powder, metal chelating agents, pigments, dyes, thickeners, etc. as necessary, and vigorously stir and stir. All you have to do is defoamer.

The quantitative ratio of each component in the composition of the present invention is not particularly determined since the required performance as a lithographic printing support varies widely, but the amount of zirconium nitrate is 2 to IO Parts by weight, preferably L7<, is 4 to 7 parts by weight. If the amount of this component is too small, the insolubilization of polyvinyl alcohol will be incomplete, and if it is too large, the hydration of the surface of the support forming the non-image area will be impaired when the composition of the present invention is used as a support. Insufficient printing ink is received, causing so-called stains on the plate surface (there is a ψ direction).

The amount of water-soluble melamine resin is 10% of polyvinyl alcohol.
50 to 200 parts by weight, preferably 80 parts by weight
~180 parts by weight.

If the amount of this component is too small, the adhesive force with the substrate tends to decrease, and if it is too large, the permanence of the surface of the support is insufficient, which tends to cause staining on the plate surface.

The amount of the inorganic powder is 50 to 200 parts by weight, preferably 70 to 150 parts by weight, based on 100 parts by weight of polyvinyl alcohol. If the amount of this component is too small, irregularities on the surface of the support will tend to vary (poor halftone reproducibility in the image area).If the amount of this component is too large, the photosensitive liquid will penetrate into the inside of the support. As a result, the amount of photosensitive liquid used increases, which is uneconomical.The particle size of this component is normally one that passes through a 320 mesh sieve, but if it is finer than that, it is uneconomical. can be used with good results.

As the substrate for applying the composition of the present invention, any material may be used as long as it is inexpensive and satisfies the required performance as a lithographic printing plate (aluminum, iron,
Metal posts such as copper, tin, zinc, and lead, or foils or plates made of alloys thereof; plastics such as polyester, polypropylene, polyimide, polyacrylonitrile, polycarbonate, polyamide, polyvinyl chloride, polyvinylidene chloride, polystyrene, and polyethylene; film,
Or sheet-like molded products, synthetic paper, art paper, coated paper,
Various materials such as cardboard and thin paper can be used.

Aluminum, zinc, iron, etc. are suitable as the metal base material. As the plastic base material, polyester, 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 of the present invention to a metal substrate, 5-sulfosalicylic acid, ethylenediaminetetraacetic acid, trans-cyclohexane-
Metal chelating agents such as 1,2 diaminetetraacetic acid may be added to the compositions of the present invention.

Also, the substrate does not need to be pretreated prior to application of the composition of the present invention, especially as long as the 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 honing, ball polishing, brush polishing, etc., or by chemically treating it by chemical conversion treatment with acid or alkali. It goes without saying that it can be increased.

〔Effect of the invention〕

The composition of the present invention applied onto a substrate is then heat treated to form a cured film suitable as a lithographic printing support. That is, although the details are unknown, polyvinyl alcohol and water-soluble melamine resin are cured and fused together by heat treatment and the action of a curing catalyst to form a film firmly adhered to the base material. In particular, polyvinyl alcohol has the function of making it insoluble in water and at the same time fixing the substance having residual hydrophilic groups to the film surface, thereby maintaining the hydrophilicity required as a support for planographic printing for a long period of time. on the other hand,
Navy? The soluble inorganic powder plays the role of forming appropriate irregularities on the surface of the support and firmly holding the photosensitive resin layer to be laminated on the surface by physical adhesive action.

As described above, the present invention relates to surface polishing, anodic oxidation, hydrophilization, and other treatments IaG′r″W that have been independently carried out in the past in order to satisfy the function of a lithographic printing plate support.
(t, L, M'r; 40) *WJK, tsf6-[1
The purpose of the present invention is to provide a composition that can function as a support for a lithographic printing plate by forming a lithographic printing plate support.

〔Example〕

Next, the present invention will be explained in more detail based on experimental examples and the like.

Experimental Examples 1 to 14 Thickness after degreasing 0.15'm/m (7), J
ISA-1100 aluminum sheet, dimension 2
00 m/m x 300 m/m, and prepared in advance a solution of 5 g of melamine resin (manufactured by Nippon Carbide Industries Co., Ltd.; product Nikaresin) dissolved in 30 g of water and 1 g of guanidine sulfamate added as a catalyst to this thin aluminum plate. Polyvinyl alcohol (Shin-Etsu Chemical Co., Ltd. product type C-17) 5% and zirconium nitrate 0
．． Mix an aqueous solution containing 05% to 0.5% as appropriate, add melamine resin to 50 to 200 parts by weight per 100 parts by weight of polyvinyl alcohol, and add colloidal silica (product of Nippon Aerosil Industries Co., Ltd.). Species C0
Each aqueous solution prepared by #FEJ was coated with a bar coater of 116 so that the amount of K84) was in the range of 20 to 200 parts by weight per 100 parts by weight of polyvinyl alcohol, and the mixture was heated at 180°C.
The mixture was dried for 3 minutes in a hot air dryer to obtain a lithographic printing support. For comparison, a sample coated with a mixture of melamine resin and colloidal silica was prepared as Experimental Example-1.

In order to conduct a test to see whether these satisfies the required characteristics as a lithographic printing plate, a negative photosensitive resin liquid was applied to the surface of each of the supports, dried for 1 minute in a hot air dryer at 120°C, and then A negative film (test pattern: 175 lines, halftone dot area 3% to 97%) was layered on the coated surface and set in a vacuum printing frame as usual, and then exposed to an ultra-high pressure mercury lamp (
After exposing for 30 seconds from a distance of 1 m using a 4KW electric capacity manufactured by Oak Seisakusho, the plate was developed using a developer, then washed with water, drained with a squeegee, poured protective ink onto the printing plate, and removed with a sponge. After observing the quality of the ink receptivity in the image area, the printing plate was washed with water, and the excess water on the printing plate was wiped off again using a squeegee. After drying, various processing and R-rating were performed. To measure the adhesion of the image area, use a Tipa set rotary abrader (wearing wheel 1cs-17, load +000E), apply offset ink to the wearing wheel, and apply the dots (175 lines, 5% screen area) of the image area. It was determined whether the halftone dots fell off after 1000 wears by rubbing the area. Evaluation of image reproducibility is based on test pattern of 175 lines and halftone dot area of 3% to 9.
The reproducibility is 7%, and the sensitivity is evaluated by the number of stages of Stethoptaburesoto (Kodanoku No. 221), and the hydrophilicity of the non-image area is evaluated by the staining status due to the above-mentioned protect ink.
Separately, after applying offset ink directly to a non-image area, water was poured onto the surface and the offset ink was measured to see if it came off.

The results are shown in Table 1.

Printing Test Example-1 A 20% solid aqueous solution was prepared with the composition of Experimental Example 4,
Width 5 pre-degreased using reverse coater
00 m/m, thickness 0.15 m/m JIS A-
A lithographic printing support was obtained by continuously coating the surface of a No. 1100 aluminum coil. The drying temperature at this time was 230° C. and the coating speed was 30 m/min.

The surface of the lithographic printing support obtained in this way was coated with a negative type photosensitive liquid in a conventional manner to form a photosensitive resin plate (from now on, PS
(referred to as a plate), cut out a part, overlaid a dark image film on the coated surface, exposed it for 40 seconds from a distance of 1 m using an ultra-high pressure mercury lamp, and applied Nipaku PS developer NN-22.
After development in step 1, the plate was washed with water and dried to prepare a lithographic printing plate. When this printing plate was printed on high-quality paper using a Heidel WORD printing machine, more than 50,000 copies could be printed without any problems.

Printing Test Example-2 A positive type photosensitive liquid was coated on the surface of the lithographic printing support obtained in the same manner as in Printing Test Example-1 in the usual manner to create a 28 plate, and a positive image film was placed on the coated surface. The plate was exposed to light for 50 seconds from a distance of 1 m using an ultra-high pressure mercury lamp in step 4, developed using a positive type developer P L-101 (manufactured by Ohka Kogyo Co., Ltd.), and then washed and dried to obtain a lithographic printing plate. Using this printing plate, printing was performed in the same manner as in Printing Test Example-1, but no problems occurred.
We were able to print over 10,000 copies.

Experimental Examples 13 to 17 The compositions shown in Table 2 below were prepared and coated on the surface of an aluminum plate in the same manner as in Experimental Examples 1 to 12 to create a support, and then evaluated for quality as a lithographic printing plate. For the purpose of printing, a photosensitive resin liquid was applied to the coated surface to prepare a °ζps plate, which was then exposed and developed to form a printing plate.As a result of evaluation, all showed good plate-making characteristics as shown in Table 3. .

1゛Table 3 Printing Test Example-3 Experimental Example-13 and Experimental Example-17 Composition Aqueous Solution Pot 2
01 was prepared, a printing plate was prepared in exactly the same manner as in Printing Test Example-1, and as a result of printing, more than 50,000 copies could be printed without any problems.

Experimental Example 18 The following composition was coated on a base material made by gluing a pre-degreased aluminum foil with a thickness of 25 μm on the surface of synthetic paper with a thickness of 0.2 m/m, and the following composition was applied at a temperature of 230°C. A heat treatment was performed for a minute to obtain a lithographic printing support.

Polyvinyl alcohol 5 (it part)
Zircon nitrate 0.05 melamine resin
8 Guanadine sulfamate 0.07 Colloidal silica 5 Water 100 Next, a PS plate was prepared according to Printing Test Example 3, and as a result of making the plate and using it for printing, it was found that there were no problems with printing (more than 50,000 copies could be printed).

Experimental Example 19 The following composition was coated on the surface of a 100 μm thick polyester film whose surface had been previously blasted by air honing and heat treated at 230° C. for 1 minute to obtain a lithographic printing support.

Polyvinyl alcohol 7 (ffi 1
part') Zircon nitrate 0.05 Melamine resin IO Guanadine sulfamic acid 0.05 Kaolin
3 Colloidal silica l Water 100 Next, prepare a PS plate according to Printing Test Example-3, make the plate and print it.
As a result of using i11, we were able to print over 50,000 copies without any problems.

Experimental Example 20 The following composition was coated on the surface of a 50 μm thick iron foil that had been previously degreased and heat treated at 200° C. for 1 minute to obtain a lithographic printing support.

Polyvinyl alcohol 6 (11 parts) Zircon nitrate 0.07 Melamine resin
6 Guanadine sulfamate 0.06 Calcium sulfate 2 Titanium oxide 2 Water 100 Next, a PS plate was created according to Printing Test Example-3, and as a result of making the plate and using it for printing, more than 50,000 copies could be printed without any problems. Ta.

Experimental Example-21 The following composition was applied to the surface of a base material made by gluing a 25μ thick polycarbonate film on both sides of the iron foil used in Experimental Example-20, and heat treated at a temperature of 170°C for 3 minutes. A support for lithographic printing was obtained.

Polyvinyl alcohol 8 (parts by weight) Zircon nitrate 0.03 Melamine resin
5 Guanadine sulfamate 0.05 Calcium carbonate 1 Aluminum oxide 2 Colloidal silica 1 Water 100 Next, a PS plate was created according to Printing Test Example-3, and as a result of making the plate and using it for printing, it was found that it was 50,000 yen without any trouble in printing. I was able to print more than one copy.

Claims (1)

[Claims] (1) A lithographic printing support layer-forming composition comprising an aqueous solution comprising polyvinyl alcohol, zirconium nitrate, a water-soluble melamine resin, and its curing catalyst, and a water-insoluble inorganic powder dispersed in the aqueous solution.