JPH0339304B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a partially saponified polyvinyl acetate-based photosensitive resin printing plate material having high image reproducibility, excellent printability, and good water developability. It is.

[Description of prior art]

Photosensitive resin plate materials for letterpress, lithographic and intaglio printing have recently been put into practical use, having a structure in which a photopolymerizable photosensitive resin layer is provided on a metal or plastic substrate. These printing plates are made by attaching a negative or positive original film with a transparent part to a photosensitive resin layer, and then irradiating it with actinic light to cause photopolymerization of the photosensitive resin layer corresponding to the transparent part of the original film. Then, a relief image is formed on the substrate by eluting the unpolymerized portion with a suitable solvent.

In this way, photosensitive resin compositions that utilize photopolymerization reactions are used for various purposes including printing plates. Among these, partially saponified polyvinyl acetate is used as the base polymer because it is a photosensitive resin that can be developed by eluting the unpolymerized portion with neutral water, and a photopolymerizable monomer is added to this to impart photosensitivity. What was done is being put into practice. Several methods have been proposed for adhering this type of photopolymer layer to a dimensionally stable substrate made of metal plastic.

First, a method has been proposed in which a layer consisting only of a water-soluble polymer is provided as an intermediate layer between a base material and a partially saponified polyvinyl acetate photosensitive resin layer (for example,
Tokuko Sho 46-42450). In this method, since the intermediate layer is not three-dimensional at all, the water resistance of the intermediate layer is insufficient, and a problem occurs in which the relief falls off from the base material during overdevelopment.

In order to improve these drawbacks, a system has been proposed in which a composition comprising partially saponified polyvinyl acetate and β-hydroxyethyl methacrylate is used in the intermediate layer (for example, US Pat. No. 3,877,939). In this case, since the intermediate layer itself undergoes thermal polymerization, a certain degree of water resistance is imparted. However, since the thermal polymerization component is a monofunctional methacrylate, the density of the crosslinked structure formed by thermal polymerization is insufficient. Therefore, during excessive development, the intermediate layer swells, causing a problem in which the relief peels off from the base material.

As a method to solve such peeling problems caused by over-development of the intermediate layer, the intermediate layer has a two-layer structure, and the lower layer in contact with the substrate is made of ethylene, which has good water resistance.
A method has been proposed in which a layer consisting of a vinyl alcohol donating polymer is provided, and a layer containing a component that crosslinks partially saponified polyvinyl acetate and partially saponified polyvinyl acetate itself, such as glyoxazole, is provided on top of the layer (for example, , Japanese Patent Publication No. 52-128701). In this case as well, if excessive washing is performed, there may be a problem in which peeling occurs between the upper and lower intermediate layers.

[Purpose of the invention]

An object of the present invention is to provide a water-developable, partially saponified polyvinyl acetate-based photosensitive resin plate material that has high image reproducibility and excellent printability, with no relief peeling off from the substrate even during excessive washing. There is a particular thing. Another object of the present invention is to provide a photosensitive resin plate material useful as a water-developable letterpress, intaglio, and lithographic printing plate.

[Structure of the invention]

That is, the structure of the present invention is a dimensionally stable photosensitive resin layer comprising partially saponified polyvinyl acetate having a degree of saponification of 60 to 99 mol% and a photopolymerizable monomer having an ethylenically unsaturated bond. In a photosensitive resin plate material coated on a base material, a 0.5 to 100μ thick composition obtained by curing a composition containing the following components A, B, and C between the base material and the photosensitive resin layer. This is a water-developable photosensitive resin plate material with an intermediate layer.

A Completely saponified or partially saponified polyvinyl acetate with saponification degree of 40 to 100 mol% 100 parts by weight B Vinyl monomer having ethylenically unsaturated bonds in the molecule 10 to 300 parts by weight C Phenol resin, melamine resin, epoxy resin, Thermosetting resin selected from the group consisting of urea resins 0.1 to 80 parts by weight [Description of preferred embodiments] The photosensitive resin layer used in the present invention has a saponification degree of
It is formed from a water-developable photosensitive resin that uses 60 to 99 mol% partially saponified polyvinyl acetate as a base polymer and blends a photopolymerizable monomer having an ethylenically unsaturated bond with this base polymer.

The degree of saponification of the partially saponified polyvinyl acetate used as the base polymer is required to be 60 to 99 mol%. That is, if the degree of saponification is less than 60 mol%, the solubility in neutral water will be significantly reduced. Furthermore, water solubility also decreases when the degree of saponification is 100 mol%. Any polymerization degree can be used, but an average polymerization degree of 200 to 2000 is preferably used. In addition, by reacting partially saponified polyvinyl acetate with ethylene oxide, -O-CH ₂ - is added to the side chain.
Those with CH ₂ - bonds introduced, those copolymerized with a small amount of less than 20 mol% of components such as allylsulfonic acid, unsaturated carboxylic acids, unsaturated aldehydes, N
- Partially saponified polyvinyl acetate, which is obtained by reacting methylol acrylamide, unsaturated epoxy, etc. with a polymer and introducing unsaturated bonds into the side chains or terminals of the polymer, also has a degree of saponification calculated from the number of hydroxyl groups remaining in the polymer. is included if it is in the range of 60 to 99 mol%. It is also possible to use a mixture of two or more types of partially saponified polyvinyl acetate having different degrees of saponification and polymerization.

As the photopolymerizable monomer having an ethylenically unsaturated group to be blended into the base polymer, any one having a certain level of compatibility with the partially saponified polyvinyl acetate of the base polymer can be used. Such photopolymerizable monomers include monofunctional vinyl monomers having hydroxyl groups such as β-hydroxyethyl (meth)acrylate and β-hydroxypropyl (meth)acrylate, and C ₂ -C ₄₀ monomers such as ethylene glycol and propylene glycol. Vinyl monomer obtained by addition of di- to penta-valent polyhydric alcohol and (meth)acrylic acid, C ₆ to C ₅₀ di- to penta-valent polyglycidyl ether such as ethylene glycol diglycidyl ether and (meth)acrylic acid A polyfunctional vinyl monomer having a hydroxyl group obtained by the addition reaction of a _C3 to _C50 unsaturated carboxylic acid such as (meth)acrylic acid and glycidyl (meth)acrylate. , a polyfunctional vinyl monomer with a hydroxyl group obtained by the addition reaction of a C ₂ - _{C 40} polyvalent saturated carboxylic acid such as oxalic acid and glycidyl (meth)acrylate, such as xylylenediamine.
Polyfunctional vinyl monomer with hydroxyl group obtained by addition reaction of _C1 to _C40 primary or secondary amine and glycidyl (meth)acrylate, (meth)acrylamide, N-methylol (meth)acrylamide, diacetone (meth)acrylamide , methylenebis(meth)acrylamide, and a condensate of ethylene glycol and N-methylol(meth)acrylamide.

It is also possible to add a high boiling point alcohol to aid in the compatibility between the partially saponified polyvinyl acetate of the base polymer and the photopolymerizable monomer. Such compounds include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, butanediol, trimethylolpropane, trimethylolethane, tetramethylolethane, glycerin, diglycerin, and the like.

A photosensitizer may also be added to rapidly photopolymerize the photosensitive resin composition.
All known sensitizers can be used as such sensitizers. Examples include benzoins, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls.

In order to increase the heat resistance stability of the photosensitive resin composition,
All known thermal polymerization inhibitors can be used. Such stabilizers include phenols,
Examples include hydroquinones and catechols. It is also possible to add trace components such as surfactants, antifoaming agents, pigments, dyes, ultraviolet absorbers, and antihalation agents.

Dimensionally stable substrates for backing the photosensitive layer made of the above photosensitive resin composition include metal materials such as steel, aluminum, copper, and zinc, and plastics such as polyester, polyamide, polyethylene, polypropylene, and polyvinyl chloride. Materials such as paper, woven cloth, etc. can be used. These materials are often molded into a flat plate shape and used as a base material, but they can also be molded into other shapes such as a cylindrical shape and used. Metal base materials can be used as they are, but they can also be used with surface treatments such as phosphoric acid treatment, chromate treatment, etching treatment, or graining treatment, or with plating such as zinc plating, tin plating, or chrome plating. Treated products can also be used. Furthermore, in order to enhance the rust-preventing power of the metal substrate, it is also possible to use a metal substrate whose surface is coated with a rust-preventing paint such as epoxy, phenol, or acrylic in advance. In order to improve the adhesion between these anticorrosion layers and the intermediate layer described below, it is also possible to provide an adhesive layer between them. As such an adhesive layer, a mixture of completely saponified or partially saponified polyvinyl acetate, an epoxy resin, and a phenolic resin can be used. In the case of a plastic base material, it is also possible to use one that has been subjected to surface matting treatment by sandblasting or chemical etching, or surface discharge treatment by corona discharge, etc., in order to improve the adhesion between the intermediate layer and the base material. It is also possible to provide an additional adhesive layer between the plastic substrate and the intermediate layer to increase the adhesion between the intermediate layer and the substrate. As such an adhesive layer, a mixture of polyester resin and diisocyanate as main components, chlorinated polypropylene, etc. are used.

In the present invention, the intermediate layer that serves to bond the photosensitive resin layer and the base material has a saponification degree of component A.
From the group consisting of 40 to 100 mol% of fully saponified or partially saponified polyvinyl acetate, a vinyl monomer with an ethylenically unsaturated group in the molecule of component B, and a phenolic resin, melamine resin, epoxy resin, and urea resin as component C. It is formed by curing a resin composition made of a selected thermosetting resin. Each component forming the intermediate layer will be explained below.

The degree of saponification of the fully saponified or partially saponified polyvinyl acetate used as component A must be in the range of 40 to 100 mol%. Saponification degree is 40
If it is less than mol%, the affinity with the partially saponified polyvinyl acetate having a degree of saponification of 60 to 99 mol%, which is the base polymer of the photosensitive layer, will be poor, resulting in insufficient adhesion between the intermediate layer and the photosensitive layer. can't get it. For these reasons, the degree of saponification of component A needs to be in the range of 40 to 100 mol%, and preferably,
It is 60-99 mol%.

Any average degree of polymerization of component A can be used, but if the degree of polymerization is too low, the water resistance after photocuring tends to be insufficient, and if the degree of polymerization is too high, it will be difficult to apply to the substrate. There is a tendency to Therefore,
The average degree of polymerization is preferably 400 to 4000.

Completely saponified or partially saponified polyvinyl acetate as component A may be one in which ethylene oxide is reacted with the side chain as in the case of the composition for the photosensitive layer;
It also includes those copolymerized with a small amount of 20 mol% or less of alysulfonic acid, etc., and those with unsaturated groups introduced into the side chains or terminals. It is also possible to use a mixture of two or more types of A component. Also, A
The components may be the same as the partially saponified polyvinyl acetate used in the photosensitive layer to be laminated, but they are not necessarily the same.

Any vinyl monomer having an ethylenically unsaturated bond in the molecule used as component B can be any one having a certain degree of compatibility with component A. Specifically, monofunctional vinyl monomers having a hydroxyl group at _C2 to _C40 such as β-hydroxyethyl (meth)acrylate, methoxyethylene glycol (meth)
_C3 to _C50 alkoxy polyalkylene glycol (meth)acrylates like acrylates,
Polyfunctional vinyl monomers obtained by the addition reaction of _C2 - _C40 polyhydric alcohols such as ethylene glycol and (meth)acrylic acid, and _C6 - _C50 polyhydric monomers such as ethylene glycol diglycidyl ether.
Polyfunctional vinyl monomer with hydroxyl group obtained by addition of pentavalent polyvalent glycidyl ether and (meth)acrylic acid, addition of _C3 to _C50 unsaturated carbon such as (meth)acrylic acid and glycidyl (meth)acrylate Polyfunctional vinyl monomers with hydroxyl groups obtained by reaction, C ₁ ~ such as xylylene diamine
A polyfunctional vinyl monomer with a hydroxyl group obtained by the addition of a _C40 primary or secondary diamine and glycidyl (meth)acrylate, and (meth)acrylamide, N-methylol (meth)acrylamide, methylenebis(meth)acrylamide, ethylene glycol and Examples include (meth)acrylamides such as a condensate of N-methylolmethacrylamide. It is also possible to use two or more kinds of B components together.

The vinyl monomer of component B plays the role of imparting water resistance to the adhesive layer by polymerizing with heat or actinic rays to form a crosslinked structure. Therefore,
If the amount is 10 parts by weight or less based on 100 parts by weight of component A, such effects cannot be exhibited. On the contrary, 300
If the amount exceeds 1 part by weight, problems such as cracks in the adhesive layer will occur due to excessive crosslinking density. For the above reasons, the amount of component B used must be in the range of 10 to 300 parts by weight, preferably 30 to 200 parts by weight, per 100 parts by weight of component A. B
It is also possible to use two or more kinds of components together.

In order to rapidly carry out thermal polymerization of component B, a known thermal polymerization initiator can be added. Such thermal polymerization initiators include peroxides such as benzoyl peroxide, nitrogen compounds such as azobisisobutyronitrile, organometallic compounds such as tetraalkyl lead, and dibenzyl disulfide. Examples include sulfides.

In order to cure component B by photopolymerization, a known photosensitizer can be added. Examples of such sensitizers include benzoins, benzophenones, matraquines, benzyls, acetophenones, and diacetyls.

Examples of the thermosetting resin selected from the group consisting of phenol resin, melamine resin, epoxy resin, and urea resin as component C include the following. Phenol resins obtained by reacting aromatic phenols such as phenol, cresol, xylenol, and dinuclear or polynuclear phenolic compounds with formaldehyde can be used. Phenol resins include resol type obtained by reacting with excess formaldehyde and novolak type obtained by reacting with excess phenol, both of which can be used. As the melamine resin, methylolmelamine, which is obtained by reacting melamine with formaldehyde, and etherified melamine resin, which is modified with butanol or ethanol, are used. As the epoxy resin, in addition to those synthesized from a polyhydric phenol such as bisphenol A and epichlorohydrin, those having a glycidyl group such as ethylene glycol diglycidyl ether can also be used. As the urea resin, methylol urea resin obtained by reacting urea and formaldehyde and alkylated methylol urea resin obtained by reacting this with methanol or the like can be used.

Component C imparts water resistance to the intermediate layer by thermosetting, and at the same time plays the role of developing adhesive strength between the base metal or plastic and the intermediate layer. Therefore, if the amount added is less than 0.1 part by weight, no effect will be achieved, and if it is added in excess of 80 parts by weight, the intermediate layer will be thermally hardened too much, resulting in a decrease in the adhesive strength between the photosensitive layer and the intermediate layer. is often significantly reduced. For these reasons, the amount of component C used is
It is necessary to range from 0.1 to 80 parts by weight, more preferably from 1 to 50 parts by weight, based on 100 parts by weight of the component. It is also possible to use two or more types of C components together.

In order to quickly heat-cure component C, it is also possible to use a curing agent that is compatible with each resin. Such curing agents include amines such as hexamethylenetetramine for phenolic resins,
In the case of melamine resins and urea resins, acid catalysts and alkali salts such as p-toluenesulfonic acid are often used, and in the case of epoxy resins, amines and organic acids or their anhydrides are often used. Of course, sufficient effects can be obtained even without adding such a curing agent by selecting an appropriate curing temperature and curing time.

All known heat stabilizers can be used to improve the storage stability of the intermediate layer composition. In addition, surfactants, antifoaming agents,
Dyes, pigments, ultraviolet absorbers, antihalation agents, etc. can also be added.

The thickness of the intermediate layer is required to be in the range of 0.5 to 100μ. When the thickness is less than 0.5 μm, adhesive strength between the photosensitive layer and the intermediate layer is often not developed, and the adhesive layer itself often dissolves into water during excessive washing. When the thickness exceeds 100 microns, the total thickness of the printing plate is determined by the printing press, so making the intermediate layer too thick will reduce the thickness of the photosensitive layer. Therefore, the depth of the obtained relief becomes shallow, and the problem that ink is supplied to areas where no relief is formed is likely to occur. For these reasons, the thickness of the intermediate layer must be between 0.5 and 100 microns, preferably between 1 and 50 microns.

In order to form an intermediate layer on a dimensionally stable substrate, the composition for the intermediate layer is dissolved in a suitable solvent such as an alcohol/water mixed solvent to form a solution, and then applied to a roll coater, gravure coater, curtain flow coater, or slit coater. After coating the base material to a predetermined thickness using a die coater, sprayer, etc., drying and appropriate curing are performed at an appropriate temperature. The thermal polymerization of component B is generally less likely to occur than the thermal curing of component C due to the inhibiting effect of oxygen.
In order to solve this problem, it is effective to add a thermal polymerization initiator to the intermediate layer composition. It is also possible to add a photosensitizer and then expose the entire surface to actinic rays after drying to completely polymerize component B through photopolymerization. When the intermediate layer is insufficiently cured, the intermediate layer lacks water resistance and solvent resistance, resulting in elution of the intermediate layer during excessive washing and swelling of the intermediate layer due to printing ink. On the other hand, if the curing progresses too much, the intermediate layer will be excessively crosslinked, resulting in insufficient adhesive strength with the photosensitive layer. Therefore, the curing conditions must be controlled within a range where the water resistance and solvent resistance of the intermediate layer and the adhesion to the photosensitive layer are compatible.

All known methods can be used to form the photosensitive resin layer on the intermediate layer formed on the dimensionally stable base material in this manner. For example, it is possible to cast a photosensitive resin solution onto the intermediate layer and remove the solvent using a drying device, or to create a photosensitive sheet using a dry film forming method and thermally laminate this sheet onto the intermediate layer. . Further, it is also possible to mold the photosensitive resin composition by discharging it from a die onto the intermediate layer in a state in which it does not contain a melting compound but contains a small amount.

The photosensitive resin layer adhered to the dimensionally stable substrate by the intermediate layer of the present invention is exposed to light after a positive or negative original image film is brought into close contact with the surface of the photosensitive layer using a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or the like. It is carried out using an actinic ray irradiation device such as a chemical lamp. At this time, photopolymerization occurs only in the portions irradiated with actinic light through the transparent portions of the original film.

After the exposure, the plate material is used in a spray type or brush type developing device using neutral water as a developing solution, by eluting and removing unpolymerized portions into developing water. Development ends when the surface of the intermediate layer is exposed. In this way, a relief is formed which is firmly adhered to the dimensionally stable substrate in the intermediate layer.

The intermediate layer of the present invention exhibits adhesion to the photosensitive layer due to the affinity between the completely saponified or partially saponified polyvinyl acetate of component A and the photosensitive layer whose base polymer is the partially saponified polyvinyl acetate of the upper layer. Further, the synergistic effect of the polymerization of the vinyl monomer as component B and the thermosetting of the thermosetting resin as component C provides the intermediate layer with sufficient water resistance and solvent resistance. Moreover, strong adhesive force is developed between the substrate and the intermediate layer when the C component is thermally cured. As mentioned above,
By combining the three components A, B and C, it has superior water resistance compared to conventional intermediate layers.
An intermediate layer having both solvent resistance and adhesive properties is obtained.

A plate material bonded to a dimensionally stable base material through this intermediate layer is most effective when used as a letterpress material, but it can also be applied to intaglio materials such as planographic materials and gravure printing materials. It is.

The present invention will be explained in more detail below in Examples.

Example 1 A composition for an intermediate layer was prepared as follows.
100 parts by weight of partially saponified polyvinyl acetate with a degree of saponification of 80 mol% and an average degree of polymerization of 1000 in ethanol/water =
It was dissolved in 250 parts by weight of a 50/50 (weight ratio) mixed solvent by heating at 80°C. Next, 100 parts by weight of diethylene glycol dimethacrylate as a vinyl monomer and 15 parts by weight of "National Xylene Resin" X-1 (manufactured by Matsushita Electric Works, Ltd.), which is a novolak type phenol resin, were added and mixed thoroughly with stirring.

The intermediate layer composition thus obtained was applied using a roll coater to a thickness of 5 μm onto a 160 μm thick steel substrate whose surface had been treated with zinc phosphate. It was then placed in an oven at 240°C for 2 minutes for drying and heat curing.

The following photosensitive resin composition for the photosensitive layer was prepared. First, partially saponified polyvinyl acetate with a saponification degree of 85 mol% and an average polymerization degree of 600 100
Part by weight was dissolved in 150 parts by weight of a mixed solvent of ethanol/water = 50/50 (weight ratio) by heating at 80°C. Next, 80 parts by weight of β-hydroxyethyl methacrylate and 20 parts by weight of ethylene glycol diacrylate were added as photopolymerizable monomers, and 2 parts by weight of benzoin isopropyl ether was added as a photosensitizer, and the mixture was thoroughly stirred and mixed.

The composition for a photosensitive layer thus obtained was cast onto the intermediate layer previously provided on the substrate so that the thickness of the photosensitive layer after drying was 395 μm. This at 60℃
The solvent was removed by placing it in an oven for 3 hours. In this way, a plate material with a total thickness of 560μ was produced.

A test negative film (133 lines with 3%, 5%, and 10% halftone dots, diameters of 200μ and 300μ independent points, widths of 50μ and 70μ with fine line parts) was vacuum-adhered to the surface of the photosensitive layer of this photosensitive resin plate material. It was exposed to ultraviolet light from a high-pressure mercury lamp for 1 minute. This exposed plate material is heated to
Development was carried out at a pressure of 3 Kg/cm ² using a spray type developing device containing neutral water at 30°C. After developing for 2 minutes, the unpolymerized portion was eluted into water and a relief was obtained on the substrate. Since the intermediate layer has good water resistance, sufficient image reproducibility was obtained without the loss of minute parts such as independent points with a diameter of 200 μ and thin lines with a width of 50 μ.

A printing test was conducted using the obtained printing plate, but no swelling of the intermediate layer due to printing ink was observed.
We were able to print 500,000 sheets without any particular problems.

Example 2 A composition for an intermediate layer was prepared as follows.
First, a partially saponified polyvinyl acetate with a degree of saponification of 85 mol% and an average degree of polymerization of 2000 was selected. 100 parts by weight of this partially saponified polyvinyl acetate was dissolved by heating at 80°C in 350 parts by weight of a mixed solvent of ethanol/water = 40/60 (weight ratio). Then, tetraethylene glycol diacrylate 60 as the vinyl monomer
parts by weight and 2 parts by weight of the photosensitizer dimethylbenzyl ketal were added. In addition, “Supervecamine” L105-, a methyl etherified melamine resin,
60 (product of Dainippon Ink Chemical Co., Ltd.) and 0.1 part by weight of p-toluenesulfonic acid as a curing accelerator were added and mixed with thorough stirring.

The intermediate layer composition solution obtained in this way was coated with epoxy anti-corrosion paint to a thickness of 2 μm in advance.
It was coated with a curtain flow coater on a chrome-plated steel plate substrate (thickness 250μ) that had been coated and cured to a dry thickness of 8μ. Then 150
Drying and curing was accomplished by passing in an oven at 0.degree. C. for 3 minutes. Under these conditions, the melamine resin was almost completely thermally cured due to the effect of the curing accelerator, but the vinyl monomer was hardly thermally polymerized and lacked water resistance, so it was exposed to ultraviolet light from a mercury lamp for 2 minutes. The vinyl monomer was photopolymerized by exposure to light to obtain a substrate with an intermediate layer.

A composition for a photosensitive layer was prepared as follows. first,
100 polymer parts of partially saponified polyvinyl acetate with a degree of saponification of 78 mol% and an average degree of polymerization of 700 are mixed with ethanol/water =
It was dissolved in 150 parts by weight of a 50/50 (weight ratio) mixed solvent at 70°C. Next, 80 parts by weight of an addition reaction product of propylene glycol diglycidyl ether and methacrylic acid was added as a photopolymerizable monomer, and further 30 parts by weight of trimethylolpropane, 3 parts by weight of dimethylbenzyl ketal as a photosensitizer, and 3 parts by weight of dimethylbenzyl ketal as a heat stabilizer were added. 0.1 part by weight of hydroquinone monomethyl ether was added and thoroughly stirred and mixed.

The photosensitive resin solution thus obtained was cast onto the chrome-plated steel plate substrate provided with the previously obtained intermediate layer so that the total thickness after drying was 950 μm. Next, the plate was placed in an oven at 60° C. for 5 hours to remove the solvent, thereby obtaining a photosensitive resin plate.

The same negative film as in Example 1 was vacuum-adhered to the surface of the photosensitive layer of this plate material, and exposed to ultraviolet light from a chemical lamp for 5 minutes. This exposed plate material was heated to 25°C in water.
Developed using a brush type developing device containing neutral water. After developing for 2 minutes, the unexposed areas were eluted into water and a relief was obtained on the substrate. Since the intermediate layer has good water resistance and sufficient adhesion to the relief, it was confirmed that independent points with a diameter of 200μ and fine lines with a width of 50μ were sufficiently reproduced. Furthermore, the results of the printing test were also good.

Example 3 A composition for an intermediate layer was prepared as follows. 100 parts by weight of partially saponified polyvinyl acetate with a degree of saponification of 96 mol% and an average degree of polymerization of 600 was mixed with ethanol/water = 30/
It was dissolved in 300 parts by weight of a mixed solvent of 70% by weight at 80°C. Next, 40 parts by weight of 2-hydroxyethyl methacrylate, 2 parts by weight of azobisisobutyronitrile as a thermal polymerization initiator, and 40 parts by weight of epoxy resin "Epicote" 826 (product of Ciel Chemical Co., Ltd.) were added and thoroughly stirred. Mixed.

The intermediate layer solution obtained in this manner was applied by gravure onto a polyester film substrate (thickness 150μ) that had been coated with a polyester/isocyanate adhesive to a thickness of 30μ and cured in advance so that the film thickness after drying was 10μ. It was applied with a coater. Then 140
Drying and curing was accomplished by passing in an oven at 0.degree. C. for 5 minutes.

On this substrate, the same photosensitive layer composition as in Example 1 was cast so that the total thickness after drying (including the substrate) was 700μ, and the solvent was removed by placing it in an oven at 60°C for 5 hours. .

The obtained plate material was made in the same manner as in Example 1 and evaluated. As a result, sufficient image reproducibility was obtained without any minute parts falling off. A printing test was conducted using the obtained printing plate, and 500,000 copies were printed without any problems.

Example 4 A composition for an intermediate layer was prepared as follows. 100 parts by weight of partially saponified polyvinyl acetate with a degree of saponification of 70 mol% and an average degree of polymerization of 1500 was mixed with ethanol/water = 60/
It was dissolved in 250 parts by weight of a mixed solvent of 40 (weight ratio) by heating at 80°C. Next, 150 parts by weight of an addition reaction product of 1 mole of propylene glycol diglycidyl ether and 2 moles of acrylic acid as a vinyl monomer was added.
In addition, “Betsukamine”, a butylated urea resin,
2 parts by weight of G-1800 (product of Dainippon Ink & Chemicals Co., Ltd.) were added and thoroughly mixed with stirring.

The intermediate layer composition solution thus obtained was applied onto a grained aluminum substrate having a thickness of 350 μm so that the thickness after drying would be 30 μm. It was then dried and heat cured by passing it through an oven at 180°C for 6 minutes.

On the thus obtained aluminum substrate with the intermediate layer, the same photosensitive composition as in Example 2 was cast so that the total thickness after drying (including the substrate) was 580μ, and the mixture was placed in an oven at 60°C. for 1 hour to completely remove the solvent.

This plate material was evaluated in the same manner as in Example 2. As a result, it was found that there is strong adhesion between the relief and the substrate down to the smallest parts. The results of the printing test also confirmed that there were no problems at all.

Claims (1)

[Claims] 1. A photosensitive resin layer containing partially saponified polyvinyl acetate with a degree of saponification of 60 to 99 mol% and a photopolymerizable monomer having an ethylenically unsaturated bond is coated on a dimensionally stable base material. In the photosensitive resin plate material formed by curing a composition containing the following components A, B, and C between the base material and the photosensitive resin layer, the thickness is 0.5 to 100 μm.
A water-developable photosensitive resin plate material characterized by having an intermediate layer of. A Completely saponified or partially saponified polyvinyl acetate with saponification degree of 40 to 100 mol% 100 parts by weight B Vinyl monomer having an ethylenically unsaturated group in the molecule 10 to 300 parts by weight C Phenol resin, melamine resin, epoxy resin, 0.1 to 80 parts by weight of a thermosetting resin selected from the group consisting of urea resins.