JPH11231546A - Photosensitive resin printing plate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-developable photosensitive resin printing plate material having high image reproducibility and excellent suitability to printing by forming a 2nd middle layer comprising partially saponified PVA having reactive groups in its side chain. SOLUTION: The photosensitive resin printing plate material has a structure consisting of a substrate, a 1st middle layer, a 2nd middle layer and a photosensitive resin layer laminated in succession. The 2nd middle layer comprises partially saponified PVA having reactive groups in its side chain. The 1st middle layer is not particularly limited if it comprises a compsn. having adhesiveness to the substrate and capable of coating with the 2nd middle layer but a material having reactive groups is preferably contained in the compsn. so as to obtain enhanced adhesive strength by chemical reaction between the 1st and 2nd middle layers. The degree of saponification of the partially saponified PVA is 40-100 mol.%, preferably 70-90 mol.%. In the case of <40 mol.%, affinity for the substrate polymer is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin printing plate material having high image reproducibility, excellent printability and good water developability. More specifically, the present invention is characterized by an adhesive layer used as an intermediate layer in a photosensitive resin plate material using a specific carboxyl group-grafted modified polyvinyl alcohol as a base polymer.

[0002]

2. Description of the Related Art A photosensitive resin plate material having a structure in which a photopolymerizable photosensitive resin layer is provided on a metal or plastic substrate for letterpress, planographic printing and intaglio printing is used in various printing fields. In these plates, a negative or positive original film having a transparent part is brought into close contact with the photosensitive resin layer, and then irradiated with actinic rays 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 an appropriate solvent. 2. Description of the Related Art A photosensitive resin composition utilizing a photopolymerization reaction is used for various applications including a printing plate. Of these, polyvinyl alcohol is used as a photosensitive resin that can be developed by dissolving the unpolymerized portion with neutral water, and a photopolymerizable monomer is blended or introduced into this resin to impart photosensitivity. Have been.

There are several known examples of such an intermediate layer for bonding a photosensitive resin layer to a substrate and a composition thereof. First, a system in which a solvent-soluble polyester resin is used as the base resin of the intermediate layer is a very excellent intermediate layer because of its good adhesive strength. Japanese Patent Publication No. 40-12104 discloses that a solvent-soluble polyester is a diisocyanate. An intermediate layer cured by heat has been proposed. Japanese Patent Publication No. 41-12987 discloses a system in which a photopolymerizable vinyl monomer is blended with a solvent-soluble polyester, and Japanese Patent Publication No. 5-67024 discloses a solvent-soluble polyester, a polyvalent isocyanate, and a polyvalent epoxy. Intermediate layers composed of compounds have been proposed.

However, in the polyester / diisocyanate system disclosed in Japanese Patent Publication No. 40-12104, the diisocyanate reacts on the one hand with the hydroxyl group at the terminal of the polyester to impart solvent resistance to the intermediate layer, and on the other hand, the residual isocyanate group makes the photosensitive layer photosensitive. Since it has the dual property of expressing contact force with the resin layer, it is difficult to achieve both the adhesive force between the photosensitive resin layer and the intermediate layer and the resistance of the intermediate layer to the ink solvent. On the other hand,
In the method of 41-12987, the intermediate layer in the portion where the relief is not formed is not cured at all, so the solvent resistance is very poor, and in order to solve this, if the substrate is transparent, the substrate example A method of irradiating the entire surface with actinic rays has been proposed, but in this method, the entire bottom portion of the photosensitive resin layer is photopolymerized and remains after development, so that the relief depth becomes shallower.

[0005] As a polyester-based intermediate layer composition having improved these points, polyester /
The system composed of polyvalent isocyanate / polyvalent epoxy compound has good adhesive strength between the photosensitive resin layer and the substrate and resistance to the ink solvent. On the other hand, because it contains highly reactive isocyanate, it is easily affected by temperature and humidity, leaving it in the air deactivates the isocyanate, causing a decrease in adhesive strength. However, there remains a problem that it is extremely difficult.

As another intermediate layer and its composition, JP-A-52-128701 discloses that a partially saponified polyvinyl alcohol and a partially saponified polyvinyl alcohol are crosslinked on a layer made of an ethylene-vinyl alcohol copolymer. An intermediate layer having a two-layer structure in which a layer made of components to be provided is provided, and an intermediate layer using a system in which a photopolymerizable monomer is blended with partially saponified polyvinyl alcohol (JP-A-3-67263) have been proposed. Also in these cases, problems such as peeling of the relief due to excessive washing and poor adhesion due to oozing of the monomer may occur.

[0007]

An object of the present invention is to provide an intermediate layer composition for bonding a substrate and a photosensitive resin layer,
To provide a water-developable photosensitive resin plate material having high adhesiveness, excellent resistance to ink solvents, high image reproducibility and excellent printability without the relief being peeled off from the substrate even during excessive washing, and Another object of the present invention is to provide a photosensitive resin plate material having a substrate that can be easily stored and managed.

[0008]

The present invention has the following structure to solve the above-mentioned problems. That is, a photosensitive resin plate material having a laminated structure in the order of a base material, a first intermediate layer, a second intermediate layer, and a photosensitive resin layer, wherein the second intermediate layer has a partial saponification having a reactive group in a side chain. A photosensitive resin plate material characterized by being composed of polyvinyl alcohol.

[0009]

Next, the present invention will be described in more detail.

The photosensitive resin layer used in the present invention is formed from a water-developable photosensitive resin containing a partially polymerized polyvinyl alcohol as a base polymer and containing a photopolymerizable monomer having an ethylenically unsaturated bond. . The degree of saponification of the partially saponified polyvinyl alcohol used as the base polymer is preferably from 60 to 99 mol%, more preferably from 70 to 90 mol%. That is, if the degree of saponification is less than 60 mol%, the solubility in neutral water may decrease, while if the degree of saponification exceeds 99 mol%, the water solubility may decrease.

The degree of polymerization of the partially saponified polyvinyl alcohol is preferably an average degree of polymerization of 300 to 2000, more preferably 500 to 1700. That is, if the average degree of polymerization is less than 300, the resulting photosensitive resin composition may be undesirably reduced in relief toughness. The average degree of polymerization is
If it exceeds 2,000, the washing speed of the obtained photosensitive resin composition may be reduced.

The partially saponified polyvinyl alcohol is reacted with ethylene oxide to form —O—CH ₂ —CH ₂ on the side chain.
Reacting a polymer with a compound having a bond introduced therein, a component obtained by copolymerizing a component such as allylsulfonic acid in a small amount of 20 mol% or less, an unsaturated carboxylic acid, an unsaturated aldehyde, N-methylolacrylamide, and an unsaturated epoxy. In the case of partially saponified polyvinyl alcohol having an unsaturated bond introduced into the side chain or terminal of the polymer, the degree of saponification calculated from the number of hydroxyl groups remaining in the polymer is in the range of 60 to 99 mol%. For example, it can be preferably used as the base polymer of the present invention. It is also possible to use a mixture of two or more kinds of partially saponified polyvinyl alcohols having different degrees of saponification and polymerization.

Examples of the photopolymerizable monomer having an ethylenically unsaturated bond include vinyl monomers or oligomers having at least one ethylenically unsaturated group in a molecule and having a certain degree of compatibility with partially saponified polyvinyl alcohol. Known ones can be used. It is also possible to add a high-boiling alcohol in order to assist the compatibility between the partially saponified polyvinyl alcohol and the photopolymerizable monomer. Examples of such compounds include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, butanediol, trimethylolpropane, trimethylolethane, tetramethylolethane, glycerin, diglycerin and the like.

These photosensitive resins generally contain an appropriate photosensitizer, and include a plasticizer, a thermal polymerization inhibitor, an ultraviolet absorber, a surfactant, an antifoaming agent, a dye and a pigment. Such known materials can be contained.

The first intermediate layer in the present invention is not particularly limited as long as it is a composition having an adhesive property to a substrate and capable of coating the second intermediate layer, but a substance having a reactive group in the composition. Are more preferable. This is because the effect of improving the adhesive strength can be obtained by expressing chemical adhesion between the first intermediate layer and the second intermediate layer.

For example, in a system composed of polyester / polyvalent isocyanate / polyvalent epoxy compound, the adhesive strength and the resistance to the ink solvent are good, but since it contains a highly reactive isocyanate, it is affected by temperature and humidity. Cheap. In the case where a highly reactive compound such as isocyanate is contained in the first intermediate layer as described above, the reactive group density is reduced by the reaction between the hydroxyl group and the isocyanate in the second intermediate layer, and the weather resistance of the base material is improved. It also has the effect of facilitating storage management.

In the system composed of polyester / polyvalent isocyanate / polyvalent epoxy compound, polyesters include hydrocarbons such as benzene, toluene, xylene and n-hexane, and halogenated hydrocarbons such as carbon tetrachloride. Polyesters that can be dissolved in one or more of ordinary organic solvents alone or in a mixture such as ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, ethers such as methyl ether, and alcohols such as methyl alcohol. Resin. Therefore, polyethylene terephthalate used for synthetic fibers and films is not preferable because it is insoluble in organic solvents.

When polyester is used for the first intermediate layer,
Its molecular weight is preferably in the range from 5,000 to 50,000, more preferably from 8,000 to 40,000. That is, when the molecular weight is less than 5000, the ink solvent resistance of the intermediate layer may be insufficient even after the curing of the polyvalent isocyanate and the epoxy compound is completed. If the molecular weight exceeds 50,000, the viscosity of the intermediate layer solution tends to be high, and in order to adjust the viscosity, the concentration of the intermediate layer solution must be extremely low. It is also possible to use a mixture of two or more polyesters.

As the polyvalent isocyanate compound, a compound having two or more isocyanate groups in a molecule can be used. Specifically, the following are exemplified. That is, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, phenyl isocyanate And adducts synthesized by adding these polyisocyanates to trimethylolpropane and the like. Further, a so-called blocked polyvalent isocyanate in which an isocyanate group is blocked with phenol or the like and these blocking agents dissociate upon heating can also be used. Preferably, a methylene diisocyanate system is used.

When a polyvalent isocyanate is used in combination with the polyester in the first intermediate layer, the polyvalent isocyanate is used in an amount of 5 to 200 parts by weight, preferably 10 to 1 part by weight, per 100 parts by weight of the polyester.
It is preferably in the range of 00 parts by weight. The polyvalent isocyanate reacts with a hydroxyl group or a carboxyl group at the terminal of the polyester and further reacts with the isocyanate groups or with water to form a crosslinked structure, thereby imparting solvent resistance to the intermediate layer. Therefore, if the addition amount is less than 5 parts by weight, the crosslinking density may not be sufficient, and the solvent resistance of the intermediate layer may be poor. Conversely, if it exceeds 200 parts by weight, the crosslinking density may be excessive, and the intermediate layer may become brittle and crack. Also, 2
It is also possible to use a mixture of more than two kinds of polyvalent isocyanates.

As the polyvalent epoxy compound, a compound having a molecular weight of 500 or more having two or more epoxy groups in a molecule is preferable, and bisphenol type epoxy such as bisphenol A and bisphenol F, and hydroxyphenyl such as tetrahydroxyphenyl are preferable. A type epoxy, a resorcin type epoxy, a novolak type epoxy, a polyglycol type epoxy, a polyolefin type epoxy, a glycidyl ether type epoxy compound, or the like can be used. These epoxy compounds include hydrocarbons such as benzene, toluene, xylene and n-hexane, ketones such as acetone and methyl ethyl ketone, halogenated hydrocarbons such as carbon tetrachloride, esters such as ethyl acetate, and ethyl cellosolve. Such as cellosolves and glycol ethers such as oxytol acetate are often dissolved alone or mixed with one or more of mixed systems and mixed with polyester or polyvalent isocyanate. Two or more polyvalent epoxy compounds can be used in combination. Particularly preferred is a bisphenol A type epoxy.

The polyvalent epoxy compound itself has a function of imparting solvent resistance to the intermediate layer by being polymerized by the action of heat or a curing agent or a catalyst. As mentioned above,
Since the polyvalent isocyanate also has a function of imparting solvent resistance to the intermediate layer, the action of the epoxy compound plays a supplementary function to the isocyanate. That is, if it is intended to sufficiently improve the solvent resistance of the intermediate layer using only isocyanate, most of the isocyanate groups are consumed for the crosslinking reaction and the residual isocyanate groups contributing to the development of adhesion to the second intermediate layer. May be insufficient. However, since the epoxy compound can be cured to impart solvent resistance, it is considered that it is possible to obtain good solvent resistance while leaving the isocyanate group required for adhesion development. preferable. The amount of the epoxy compound to be added is preferably in the range of 0.5 to 150 parts by weight, more preferably 1 to 100 parts by weight, based on 100 parts by weight of the polyester. If the amount is less than 0.5 part by weight, the effect of adding the epoxy compound may not be sufficient, and if it exceeds 150 parts by weight, the crosslinking density may be excessive.

The second intermediate layer in the present invention is composed of partially saponified polyvinyl alcohol having a reactive group in a side chain. If the partially saponified polyvinyl alcohol does not have a reactive group in the side chain, it has excellent adhesiveness and resistance to ink solvents, and has excellent image reproducibility without the relief peeling off from the substrate even during excessive washing. The object of the present invention of obtaining a water-developable photosensitive resin plate material having printability cannot be achieved.

The degree of saponification of the partially saponified polyvinyl alcohol used for the second intermediate layer is preferably 40 to 100 mol%, more preferably 70 to 90 mol%. That is, the degree of saponification is 40
If the amount is less than mol%, the affinity of the photosensitive resin layer with the base polymer may be poor, and it may not be easy to obtain a sufficient adhesive force between the second intermediate layer and the photosensitive resin layer.

The partially saponified polyvinyl alcohol used for the second intermediate layer has a reactive group in the side chain as described above. The reactive group includes a partially saponified polyvinyl alcohol reacted with carboxylic anhydride. It is preferable that the polymer is modified by the addition of an unsaturated epoxy compound to thereby impart reactivity to the polymer by radical polymerization, since the effect of the present invention can be particularly excellent.

As for the degree of polymerization of the partially saponified polyvinyl alcohol used for the second intermediate layer, those having an average degree of polymerization of 300 to 2,000, preferably 500 to 1800, and particularly preferably 1000 to 1800 can be preferably used. That is, if the average degree of polymerization is less than 300, the water resistance of the substrate may be insufficient, and if the average degree of polymerization exceeds 2,000, the viscosity of the solution may be high, and it may be difficult to apply the composition on a substrate. There is.

The carboxylic anhydride preferably used for modifying the partially saponified polyvinyl alcohol used as the second intermediate layer in the present invention includes an intramolecular anhydride from a carboxylic acid having two or more carboxyl groups in the molecule. Are preferred, as specific examples, succinic anhydride, maleic anhydride, acetic anhydride, trimellitic anhydride, phthalic anhydride,
Examples thereof include pyromellitic anhydride, glutaric anhydride, hydrogenated phthalic anhydride, and naphthalene dicarboxylic anhydride. Among these, succinic anhydride, maleic anhydride, trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, glutaric anhydride, hydrogenated phthalic anhydride, naphthalene dicarboxylic anhydride are preferred, and succinic anhydride is particularly preferred. . These carboxylic anhydrides can be used alone or in combination of two or more. Further, a carboxylic anhydride having two or more carboxyl groups in the molecule and containing no olefinically unsaturated bond is more preferable.

The modification conditions for the modified polyvinyl alcohol are as follows:
It is easy to introduce carboxyl groups at a high reaction rate,
From the viewpoint of effectively preventing the remaining carboxylic anhydride and its hydrolyzate from remaining as impurities, a method by a reaction in a molten state is preferable to a method in the presence of a solvent. The reaction temperature at this time is, in the case of performing a melt reaction in the absence of a solvent, a temperature range in which either partially saponified polyvinyl alcohol or carboxylic anhydride is melted and a sufficient reaction rate is obtained, that is, 100 ° C. ~ 400 ° C is good. However, if the reaction temperature is too high, the cross-linking reaction of polyvinyl alcohol proceeds as a side reaction.
° C, especially 100 ° C to 200 ° C.

In the above reaction, it is suitable to use the carboxylic anhydride in the range of 0.001 to 20 parts by weight based on 100 parts by weight of the partially saponified polyvinyl alcohol. The lower limit of the charged amount of the carboxylic anhydride is further 0.
1 part by weight, 1 part by weight, and 3 parts by weight are preferred. On the other hand, the upper limit of the charged amount is more preferably 10 parts by weight and then 5 parts by weight. If the amount of the carboxylic anhydride is less than 0.001 part by weight, a satisfactory modifying effect is difficult to appear, and if it is more than 20 parts by weight, a side reaction such as a cross-linking reaction in a molten state may have an adverse effect, and a good result is not always obtained. Not always.

In the present invention, the modified polyvinyl alcohol used for the second intermediate layer is obtained by reacting a partially saponified polyvinyl alcohol and preferably a carboxylic anhydride, and then adding an unsaturated epoxy compound to the carboxyl group of the side chain. It is preferable that radical polymerization reactivity by an unsaturated bond is imparted, and chemical adhesion is exhibited between the first intermediate layer and the photosensitive resin layer. Specific examples of the unsaturated epoxy compound include glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, and 3,4-epoxycyclohexyl methacrylate. These compounds can be used alone or in combination of two or more. An unsaturated epoxy compound obtained by an addition reaction of an unsaturated compound having one or more active hydrogens in a molecule and an unsaturated compound having two or more epoxy groups in a molecule is also included.

The amount of the unsaturated epoxy compound used in the present invention is preferably at least 0.1 part by weight based on 100 parts by weight of the modified polyvinyl alcohol. If the amount of the unsaturated epoxy compound is less than 0.1 part by weight, the effect of improving photocrosslinkability may not be sufficiently obtained.

[0032] Other small components may be added to the intermediate layer composition of the present invention. Examples of such additives include plasticizers, pigments, dyes, ultraviolet absorbers, antihalation agents, surfactants, and photopolymerizable vinyl monomers. As the dye, an azo dye is particularly exemplified.

Examples of the base material used for the photosensitive resin plate material of the present invention include those having good dimensional stability as described below. That is, a gold-plated material such as steel, aluminum, zinc, and copper, a plastic material such as polyethylene terephthalate, polyamide, and polypropylene; paper; and woven fabric. In the case of a metal material, a material subjected to a plating treatment such as chromium plating, a chemical conversion treatment such as a phosphoric acid treatment, or a surface treatment such as graining is preferably used. It is also possible to apply and cure an epoxy-based paint or the like in advance on the surface of the metal base material for the purpose of rust prevention or the like. In the case of a plastic material, a material which has been subjected to a surface treatment such as a sand blast treatment, a chemical etching treatment, a discharge treatment such as corona discharge, and a plasma treatment is also preferably used. These materials are used as a base material of a photosensitive resin plate material in an arbitrary shape such as a flat plate or a cylinder, but are most commonly used as a flat plate base material.

The simplest method of providing an intermediate layer on a dimensionally stable substrate is to apply a composition solution for an intermediate layer to each of a first intermediate layer and a second intermediate layer, and then remove the solvent. is there. As a coating method, a known method such as a roll coater, a curtain flow coater, a slit die coater, a gravure coater, and a spray can be applied. The removal of the solvent is generally performed by blowing hot air in a drying furnace.

The thickness of the first intermediate layer is preferably in the range of 0.5 to 100 μm, more preferably 2 to 50 μm. 0.5 thickness
If it is less than μm, the adhesive force between the first intermediate layer and the second intermediate layer may not be exhibited, and conversely, the thickness of the first intermediate layer may be 10
If it exceeds 0 μm, in the case of letterpress material, the overall depth is limited by the printing machine, so the relief depth becomes shallow,
There is a possibility that a problem that the printing ink is supplied to the surface of the plate material in a portion having no relief may occur.

Similarly, the thickness of the second intermediate layer is 0.5 to 100 μm,
More preferably, it is in the range of 2 to 50 μm. Thickness
When the thickness is less than 0.5 μm, the first intermediate layer and the second intermediate layer or the adhesive force between the second intermediate layer and the photosensitive resin layer may not be exhibited, and conversely, the thickness of the second intermediate layer is 100 μm. Beyond that, in the case of letterpress materials, the overall thickness is limited by the printing machine, so the depth of the relief becomes shallow, and there is a risk that printing ink will be supplied to the plate material surface where there is no relief. is there.

As a method for providing a photosensitive resin layer on a substrate provided with an intermediate layer according to the present invention, all known methods can be used. For example, a photosensitive sheet is obtained from a photosensitive resin solution by a dry film forming method, a method of thermally laminating the photosensitive sheet on an intermediate layer, and removing the solvent in a drying furnace after directly casting the photosensitive resin solution on the intermediate layer. A method of forming a photosensitive resin layer by distilling out most of the solvent from the photosensitive resin solution, heating the mixture with an extruder, discharging onto an intermediate layer, and forming a photosensitive resin layer without a drying step. It is.

In order to form a relief image for printing using the photosensitive resin composition of the present invention, a negative or positive original film is adhered onto the photosensitive resin layer prepared by the above method, and a film of 300 to 400 nm is formed. The photosensitive resin layer is made insoluble by photopolymerization by irradiating ultraviolet rays having a wavelength as a center. Next, a relief image is formed on the support by eluting the unpolymerized portion into water with a spray developing device or a brush developing device using neutral water.

[0039]

The present invention will be described in more detail with reference to the following examples.

(Example 1) [Modification of partially saponified polyvinyl alcohol] Succinic anhydride was added to 4% by weight of partially saponified polyvinyl alcohol obtained from polyvinyl acetate and having a number average polymerization degree of 500 and a saponification degree of 70 mol%. After dry blending, the mixture was melt-kneaded with a single screw extruder set at a temperature of 210 ° C. to obtain a pale yellow transparent modified polyvinyl alcohol.

[Preparation of Photosensitive Resin Layer Composition] 100 parts by weight of the previously synthesized modified polyvinyl alcohol was added to 200 parts by weight of a mixed solvent of ethanol / water = 50/50 (weight ratio). Dissolved over 3 hours. Subsequently, 5 parts by weight of glycidyl acrylate was added and stirred for 30 minutes to introduce an unsaturated bond into the polymer component. Subsequently, 35 parts by weight of an addition reaction product of 1 mol of propylene glycol diglycidyl ether and 2 mols of acrylic acid and 35 parts by weight of 2-hydroxyethyl acrylate as a photopolymerizable monomer, 3 parts by weight of dimethyl pendyl ketal as a photoinitiator, and other components As a component, 10 parts by weight of diethylene glycol and 0.1 part by weight of hydroquinone monomethyl ether were added and sufficiently stirred and mixed to prepare a photosensitive resin composition solution.

[Preparation of Composition for First Intermediate Layer] "Nichigo Polyester" L which is a polyester resin soluble in an organic solvent
P-035 (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight: about 20,000) 100
Parts by weight of toluene / methyl ethyl ketone = 80/20
2,000 parts by weight of the mixed solvent (weight ratio) was heated to 80 ° C. and dissolved. After cooling, 170 parts by weight of hexamethylene diisocyanate as a polyvalent isocyanate, and "Epicoat" 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) as an epoxy compound,
Molecular weight about 380) 60 parts by weight, 50 parts by weight of "EPON" DMP-30 (manufactured by Hanoi Chemical Co., Ltd.) as an epoxy curing agent, 1 part by weight of ethyl methyl imidazole as a curing catalyst, and an azo-based yellow face as an antihalation agent A certain “Yellow” P
R359 (manufactured by Sumika Color Co., Ltd.) (50 parts by weight) was added, and the mixture was thoroughly stirred and mixed.

[Preparation of Composition for Second Intermediate Layer] 20 parts by weight of the modified polyvinyl alcohol synthesized above was mixed with ethanol / water =
It was added to 200 parts by weight of a 50/50 (weight ratio) mixed solvent and dissolved at 70 ° C. for 3 hours. Next, 2 parts by weight of glycidyl acrylate was added and stirred for 30 minutes to obtain a second intermediate layer composition solution.

[Coating of Intermediate Layer] The composition solution for the first intermediate layer obtained as described above was applied to a chromium-plated steel sheet (250 mm thick).
μm), after coating with a roll coater so that the film thickness after dry operation becomes 10 μm, put in a 250 ° C. oven for 1 minute to remove the solvent, and then apply the second intermediate layer on the first intermediate layer. The composition was applied by a roll coater so that the film pressure after drying was 5 μm, and then placed in an oven at 160 ° C. for 1 minute to remove the solvent to obtain a substrate.

[Preparation of Plate Material] A 950 μm-thick laminated plate material was obtained by casting the photosensitive resin layer composition on the above substrate and drying it in a hot air oven at 60 ° C. for 5 hours. Was.

[Evaluation of plate performance] A gray scale negative film for sensitivity measurement and a negative film for evaluating image reproducibility (133 lines,
(3%, 5%, 10% halftone dots, 200 μm and 300 μm diameter independent points, and 50 μm and 70 μm thin lines) were adhered in vacuum on the photosensitive resin layer and exposed to a high pressure mercury lamp for 2 minutes. Then 25
When development was performed using a brush-type developing device containing neutralized water at ℃ ° C, the non-image area was completely eluted in water in 2 minutes and 30 seconds, and a relief image was obtained. As a result of evaluating the obtained relief, the intermediate layer shows good water resistance,
The image area was sharply reproduced up to a fine part such as a 200 μm independent point and a 50 μm fine line, and sufficient image reproducibility was obtained.

When a printing test was carried out using this resin plate material, a printed matter having a sharp print without thickening of image lines was obtained. Even after printing 300,000 passes, no problem such as peeling of the relief occurred, and the adhesion performance between the relief and the substrate could be confirmed. No swelling or dissolution of the intermediate layer by the ink solvent was observed.

(Example 2) [Modification of partially saponified polyvinyl alcohol] Maleic anhydride was added to partially saponified polyvinyl alcohol obtained from polyvinyl acetate and having a number average polymerization degree of 1700 and a saponification degree of 80 mol%.
After dry blending by weight, the mixture was melt-kneaded with a single screw extruder set at a temperature of 100 ° C. to obtain a pale yellow transparent modified polyvinyl alcohol.

[Preparation of Photosensitive Resin Layer Composition] 100 parts by weight of partially saponified polyvinyl alcohol having a number average degree of polymerization of 600 and a degree of saponification of 85 mol% was mixed with ethanol / water = 50/50 (weight ratio).
Was added to 150 parts by weight of a mixed solvent, and dissolved at 80 ° C. for 3 hours. Subsequently, 5 parts by weight of glycidyl acrylate was added and stirred for 30 minutes to introduce an unsaturated bond into the polymer component.
Subsequently, 35 parts by weight of an addition reaction product of 1 mol of propylene glycol diglycidyl ether and 2 mol of acrylic acid as a photopolymerizable monomer and 2-hydroxyethyl acrylate 3
5 parts by weight, dimethylpentyl ketal 3 as a photoinitiator
10 parts by weight of diethylene glycol and 0.1 parts by weight of hydroquinone monomethyl ether as other components were added, and the mixture was sufficiently stirred and mixed to prepare a photosensitive resin composition solution.

[Preparation of Composition for First Intermediate Layer] The same composition as in Example 1 was prepared.

[Preparation of Composition for Second Intermediate Layer] 20 parts by weight of the modified polyvinyl alcohol modified under the above conditions were added to 200 parts by weight of a mixed solvent of ethanol / water = 50/50 (weight ratio). For 3 hours. Next, 5 parts by weight of glycidyl acrylate was added and stirred for 30 minutes to obtain a second intermediate layer composition solution.

[Application of Intermediate Layer] The composition solution for the first intermediate layer obtained as described above was applied to a chromium-plated steel plate (thickness: 250
μm) after coating with a roll coater so that the film thickness after the dry operation becomes 10 μm, put in a 250 ° C. oven for 1 minute to remove the solvent, and then apply the second intermediate layer on the first intermediate layer. The composition was applied by a roll coater so that the film pressure after drying was 5 μm, and then placed in an oven at 160 ° C. for 1 minute to remove the solvent to obtain a substrate.

[Preparation of Plate Material] A 950 μm-thick laminated plate material was obtained by casting the photosensitive resin layer composition on the above substrate and drying it in a hot air oven at 60 ° C. for 5 hours. Was.

[Evaluation of Plate Performance] The same negative film as in Example 1 was vacuum-contacted on the photosensitive resin layer, exposed to a chemical lamp for 3 minutes, and developed with a brush type developing device containing 25 ° C. neutralized water. When the test was performed, the non-image area was completely eluted in water in 3 minutes, and a relief image was obtained. As a result of evaluating the obtained relief, the image area was 3% halftone dot, 200 μm independent point, 50 μm
Even the fine parts such as m fine lines were sharply reproduced.

The results of the printing test were also good.

(Comparative Example 1) Number average polymerization degree 500, saponification degree 7
20 parts by weight of partially saponified polyvinyl alcohol of 0 mol% was added to 200 parts by weight of a mixed solvent of ethanol / water = 50/50 (weight ratio) without denaturation to prepare a second intermediate layer composition solution. A photosensitive resin plate material was prepared in the same manner as in Example 1.

Exposure and development were performed in exactly the same manner as in Example 1. As a result, the non-image area was completely eluted in water in 2 minutes and 30 seconds, and a relief image was obtained. However, in the image portion, a fine portion such as a 200 μm independent point and a 50 μm fine line was partially cut, exhilarated and markedly distorted.

(Comparative Example 2) 20 parts by weight of a partially saponified polyvinyl alcohol having a number average polymerization degree of 500 and a saponification degree of 70 mol% was modified with 200 parts by weight of a mixed solvent of ethanol / water = 50/50 (weight ratio). Example 1 was repeated except that 5 parts by weight of a photopolymerizable monomer (an addition reaction product of 1 mol of propylene glycol diglycidyl ether and 2 mol of acrylic acid) was used as a second intermediate layer composition solution. When a photosensitive resin plate material was prepared in the same manner as in Example 1, bleed-out of the photopolymerizable monomer occurred in the intermediate layer, and no adhesive force was developed between the intermediate layer and the photosensitive resin layer.

[0059]

The photosensitive resin plate material of the present invention can provide a photosensitive resin printing plate material having high image reproducibility, excellent printability, and good water developability.

The photosensitive resin composition of the present invention provides a printing plate material having high sensitivity, high definition image reproducibility, excellent water developability, and excellent relief toughness. Although it is particularly suitable as a relief printing material, it can also be used as a lithographic printing material, an intaglio printing material or a stencil printing material.

The photosensitive resin plate material of the present invention can be used for a photosensitive resin plate material in which a solvent-soluble polyester / diisocyanate system has been used as an intermediate layer. The adhesive strength and the resistance of the intermediate layer to the ink solvent can be compatible. Further, it is possible to solve poor weather resistance and difficulties in storage management of a substrate provided with an intermediate layer, which are observed in a system composed of polyester / polyvalent isocyanate / polyvalent epoxy compound. Further, an intermediate layer having a two-layer structure in which a layer made of a partially saponified polyvinyl alcohol and a component for crosslinking the partially saponified polyvinyl alcohol itself is provided on a layer made of an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol Problems such as peeling of relief due to excessive washing and poor adhesion due to exudation of monomers, as seen in photosensitive resin plate materials using an intermediate layer using a system in which a photopolymerizable monomer is blended, It is improved by using a partially saponified polyvinyl alcohol having a two-layer structure of one intermediate layer and a second intermediate layer, and a second intermediate layer on the photosensitive resin layer side, having a reactive group capable of performing a radical reaction in a molecule. You.

Claims (4)

[Claims] 1. A photosensitive resin plate material having a laminated structure in the order of a substrate, a first intermediate layer, a second intermediate layer, and a photosensitive resin layer, wherein the second intermediate layer has a reactive group in a side chain. A photosensitive resin plate material comprising a partially saponified polyvinyl alcohol. 2. The photosensitive resin plate material according to claim 1, wherein the partially saponified polyvinyl alcohol forming the second intermediate layer has a saponification degree of 40 to 100 mol%. 3. The photosensitive resin plate material according to claim 1, wherein the partially saponified polyvinyl alcohol forming the second intermediate layer has a number average degree of polymerization of 300 to 2,000. 4. The partially saponified polyvinyl alcohol having a reactive group forming the second intermediate layer is obtained by modifying the partially saponified polyvinyl alcohol with carboxylic anhydride and then adding an unsaturated epoxy compound. The photosensitive resin plate material according to any one of claims 1 to 3, wherein the polymer is provided with reactivity by radical polymerization.