JP2002023349A - Photosensitive resin relief printing plate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin relief printing plate material excellent in water developability and image reproducibility in printing using a photosensitive resin relief printing plate and useful for manufacturing a printing plate having a sharp relief structure. SOLUTION: In the photosensitive resin relief printing plate material with at least a substrate and a photosensitive layer, the photosensitive layer has a multilayer structure having different UV transmittances (measured at 365 nm wavelength every 100 μm thickness).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin relief printing plate material suitable as a material for producing a printing plate material having high image reproducibility, printability and good water developability.

[0002]

2. Description of the Related Art A photosensitive resin plate material for letterpress printing having a structure in which a photopolymerizable photosensitive resin composition layer is provided on a base material such as metal or plastic has been replaced by a conventional metal plate in the printing field. The mainstream of. These plate materials are prepared by bringing a negative or positive original film with a transparent portion into close contact with the photosensitive resin layer, and then irradiating with actinic rays to photopolymerize the photosensitive resin layer corresponding to the transparent portion of the original film. Then, the unpolymerized portion is eluted into an appropriate solvent to form a relief on the substrate.

[0003] The photosensitive resin composition utilizing the photopolymerization reaction as described above is used for various applications including printing plates. Among them, a system using a soluble polyamide, fully saponified or partially saponified polyvinyl acetate as a base resin has been proposed as a polymer which can be developed by eluting an unpolymerized portion with neutral water. This known example can be roughly classified into three systems. The first system is to impart photosensitivity by blending a soluble polyamide and partially saponified polyvinyl acetate with a photopolymerizable monomer having an ethylenically unsaturated bond. Such known examples are disclosed in JP-B-46-39401, JP-B-50-30.
No. 903, JP-A-50-27602, JP-A-48-87903, JP-A-57-124730, JP-A-57-212217, and JP-B-59-217.
No. 50051, JP-A-59-172644,
JP-A-60-51833 can be mentioned.

A second system is to introduce an unsaturated group into a hydroxyl group of a soluble polyamide or partially saponified polyvinyl acetate. Such a well-known example is disclosed in JP-B-48-6.
No. 6151, JP-B-63-37369, JP-A-48-66151, JP-A-50-45087, JP-A-54-13890, JP-A-58-2
1736, JP-A-59-176303, JP-A-59-185332, JP-A-1-60133
No. gazette.

A third system is disclosed in Japanese Unexamined Patent Publication No. 3-32744.
No. 58, Japanese Patent Application Laid-Open No. 4-4283749, a carboxyl group is added to a partially saponified polyvinyl acetate side chain to make the polymer itself reactive, and further, an unsaturated epoxy compound is added to the carboxyl group. Is reacted in the system to introduce a double bond into the polymer to enhance photoreactivity.

However, the demand for higher definition of printed matter is increasing year by year, and the development of a high definition plate material for letterpress is urgently required. On the other hand, when the relief plate material is compared with a lithographic plate represented by a PS plate and a lithographic plate without water, it can be said that the resolution and image reproducibility of the plate material are several steps lower than those of the lithographic plate.

[0007] A photosensitive resin relief material having a relief depth of 0.1 to 2.0 mm, which is common in the resin relief printing technology field, does not generally provide a favorable sharp relief structure and often has a side surface having a gentle slope. Form.

[0008]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a printing plate having excellent water developability and image reproducibility and having a sharp relief structure in printing using a photosensitive resin relief printing plate. An object of the present invention is to provide a photosensitive resin relief printing plate material useful for manufacturing.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to develop a photosensitive resin relief printing plate material having the above-mentioned excellent characteristics, and have been made of a specific photosensitive resin composition. By forming a multilayer structure having different ultraviolet transmittance (measured value at a wavelength of 365 nm and a thickness of about 100 μm) in the photosensitive layer of the photosensitive resin letterpress material for printing, a sharp relief suitable for the purpose is constituted. They found that a photosensitive resin relief plate material could be provided, and based on this finding, completed the present invention.

That is, the present invention provides: "A photosensitive resin relief printing plate having at least a support and a photosensitive layer, wherein the photosensitive layer has a multilayer structure composed of layers having different ultraviolet transmittances (measured at a wavelength of 365 nm and a thickness of about 100 μm). Resin letterpress material. "

Also preferably, 2. "At least one layer constituting the photosensitive layer comprises (A) a base resin, (B) a photoinitiator,
(C) a photopolymerizable unsaturated compound having an ethylenic double bond in the molecule, and (D) a photosensitive resin relief printing plate material according to the above-mentioned 1, which comprises at least a compound that absorbs ultraviolet light; More preferably, 3. "(D) The photosensitive resin relief printing plate according to the above item 2, wherein the compound absorbing ultraviolet rays has a molecular weight of 10,000 or more".

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail.
The photosensitive resin relief printing plate of the present invention has at least a support and a photosensitive layer, and the photosensitive layer has an ultraviolet transmittance (a wavelength of 365 nm,
It has a multilayer structure composed of layers having different thicknesses (measured value per 100 μm thickness).

[0013] The ultraviolet transmittance is measured by measuring a photosensitive layer sheet (thickness is not specified) with a spectrophotometer and measuring the ultraviolet transmittance at 365 nm.
In order to convert to about m, the ultraviolet transmittance at a thickness of 100 μm can be obtained by calculating from Lambert's law.

In the present invention, as the support, a metal plate such as steel, stainless steel, aluminum or copper, a plastic sheet such as polyester film, or a synthetic rubber sheet such as styrene-butadiene copolymer can be used.

In the present invention, the photosensitive layer means a layer which undergoes a photocuring reaction when irradiated with actinic rays.

In the present invention, the photosensitive layer is formed from multiple layers. Here, the multilayer means that it is composed of two or more layers. In the present invention, the photosensitive layer preferably comprises 2 to 10 layers, and more preferably 2 to 3 layers from the viewpoint of productivity.

Each layer forming these photosensitive layers has a thickness of 365 nm.
UV transmittance at wavelength of (value per 100μm thickness)
Need to be different. UV transmittance difference is 1% ~
Preferably it is 99%. When the photosensitive layer has a multilayer structure of three or more layers, it is not necessary that the UV transmittance at 365 nm wavelength (value per 100 μm thickness) of each layer is different, and the UV transmittance at 365 nm wavelength (thickness) is different. It is sufficient that there is at least one set of layers having different values per 100 μm).

Hereinafter, preferred photosensitive layer compositions in the present invention will be described.

The photosensitive layer may comprise (A) a base resin, (B) a photopolymerizable unsaturated compound having an ethylenic double bond, and (C) a photosensitive resin composition containing a photoinitiator as an essential component. preferable.

In the present invention, at least one of the photosensitive layers contains (D) a compound that absorbs ultraviolet light, so that the ultraviolet light transmittance at a wavelength of 365 nm (thickness of 1) is obtained.
(Values around 00 μm) are preferably different.

Hereinafter, each component will be described.

(A) Examples of the base resin include soluble polyamide and partially saponified polyvinyl acetate. Soluble means that it can be dissolved or dispersed in a solvent. As a soluble polyamide, the number average molecular weight in the molecular chain is 150-3.
A polyoxypropylene segment or a poly (oxyethylene / oxypropylene) copolymer segment of 10 to 70% by weight (for example, described in JP-B-59-500051) or a polyamide containing basic nitrogen (for example, JP-A-50-7605) and a polyamide having an ammonium salt type nitrogen atom (for example, described in JP-A-53-76602).

Also, as partially saponified polyvinyl acetate,
Saponification degree 60-99 mol%, number average polymerization degree 300-200
Polymers having 0 are preferably used.

Further, a partially saponified polyvinyl acetate obtained by introducing a polymerizable unsaturated bond into a part thereof can also be used. For example, modified polyvinyl alcohol obtained by reacting partially saponified polyvinyl acetate (that is, a vinyl acetate / vinyl alcohol copolymer) with a dicarboxylic anhydride to add a carboxyl group to a side chain. As a specific production method, an acid anhydride is mainly added to partially saponified polyvinyl acetate having a saponification degree of 60 to 99 mol% and a number average polymerization degree of 300 to 2,000. As the acid anhydride, maleic anhydride, trimellitic anhydride, succinic anhydride, phthalic anhydride, pyromellitic anhydride, glutaric anhydride, hydrogenated phthalic anhydride, naphthalene dicarboxylic anhydride and the like can be used. The content of the acid anhydride residue is based on the sum of vinyl acetate units and vinyl alcohol units before the reaction.
The range of 0.1 to 15 mol% is preferred. Content is 0.1
If it is less than mol%, the image reproducibility, water resistance, durability during printing, etc. will not be much different from the case where unmodified fully saponified or partially saponified polyvinyl acetate is used, while if it exceeds 15 mol%, the water solubility of the polymer will be less. It decreases significantly. As a method for reacting partially saponified polyvinyl acetate with an acid anhydride to introduce a carboxyl group into a polymer side chain, the partially saponified polyvinyl acetate is dissolved in a solvent, the acid anhydride is reacted in a catalyst, and then the reaction is performed again. A method of producing denatured polyvinyl alcohol by repeating precipitation-drying, or a method of partially saponifying an organic solvent which can swell without dissolving partially saponified polyvinyl acetate such as acetone or N, N-dimethylformamide (DMF). There is a method of swelling vinyl acetate and reacting the acid anhydride with the addition of a catalyst, followed by drying to obtain a modified polyvinyl alcohol.

In order to further improve the image reproducibility of the minute portion, a resin obtained by introducing an unsaturated bond, preferably an unsaturated epoxy compound, into the above resin is preferably used as the base resin (A). Examples of such unsaturated epoxy compounds include compounds having one or more epoxy groups and one or more acrylic or vinyl groups in the molecule, and include glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate,
3,4-Epoxycyclohexyl methacrylate is a typical compound, and is obtained by an addition reaction of an unsaturated compound having one or more active hydrogens in a molecule and a compound having two or more epoxy groups in a molecule. Such unsaturated epoxy compounds can also be used.

The polymer is obtained by reacting the carboxyl group or amino group at the terminal or side chain of the soluble polyamide shown as (A) the base resin, the carboxyl group of the modified polyvinyl alcohol, or the partially saponified polyvinyl acetate with the acid anhydride. To the carboxyl group added to the side chain,
Further, by reacting the unsaturated epoxy compound, an unsaturated group can be introduced into the polymer itself, which brings about an effect of significantly improving photoreactivity. In this reaction, the modified polyvinyl alcohol and the unsaturated epoxy compound may be reacted in a separate step, or the unsaturated epoxy compound is introduced into the carboxyl group in the polymer by an addition reaction in the step of preparing the photosensitive resin composition. It is also possible.

When a polymerizable unsaturated bond is introduced into the base resin (A) by the unsaturated epoxy compound, the unsaturated epoxy compound is added to 100 parts by weight of the base resin into which the polymerizable unsaturated bond is not introduced. A range of 1 to 10 parts by weight is preferred. If it is 10 parts by weight or less, the compatibility with the polymer or the photopolymerizable monomer will not be lost, and no exudation or precipitation will occur on the plate surface, and the density of the crosslinked structure generated by photopolymerization will be excessive. Thus, the relief made by the plate is hard and brittle, so that cracks do not occur during printing.

As the photopolymerizable unsaturated compound (B) having an ethylenic double bond in the molecule, any compound can be used as long as it is addition polymerizable, but (A) a compound compatible with the base resin Is preferably used. Specifically, the following are mentioned. 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2
-Hydroxybutyl methacrylate, 3-chloro-2-
Monoacrylates and monomethacrylates having a hydroxyl group such as hydroxypropyl acrylate and 3-chloro-2-hydroxypropyl methacrylate. Polyhydric acrylates and methacrylates obtained by reacting a polyhydric alcohol such as ethylene glycol with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Polyhydric acrylates and polyhydric methacrylates having a hydroxyl group which are synthesized by the reaction of a polyhydric glycidyl ether such as ethylene glycol diglycidyl ether and an unsaturated carboxylic acid such as acrylic acid and methacrylic acid. Polyhydric acrylates and methacrylates having a hydroxyl group, which are synthesized by reacting an unsaturated epoxy compound such as glycidyl methacrylate with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, methylenebisacrylamide, N-methylol acrylamide or polyhydric acrylamide obtained by condensation reaction of polyhydric alcohol with N-methylol methacrylamide and polyhydric acrylamide Acrylamide-based photopolymerizable monomers such as methacrylamide, and the like, preferably acrylic or methacrylic esters having a hydroxyl group and acrylic or methacrylamide.

(B) in the photosensitive resin letterpress material of the present invention
The content of the photopolymerizable unsaturated compound having an ethylenic double bond in the molecule is in the range of 20 to 200 parts by weight, preferably 50 to 150 parts by weight, per 100 parts by weight of the base resin (A). . If it is 20 parts by weight or more, the density of the crosslinked structure generated by photopolymerization does not become insufficient,
Sufficient image reproducibility is obtained. When the content is 200 parts by weight or less, the density of the crosslinked structure generated by photopolymerization does not become excessive, and the relief made by the plate becomes very brittle, causing problems such as cracks in the relief during printing. Nothing.

In the present invention, the (C) photoinitiator has a function of initiating the polymerization of a (B) photopolymerizable unsaturated compound having an ethylenic double bond in the molecule by absorbing light. Usually, those having a radical polymerization initiating property are preferably used. As the photoinitiator (C), benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls and the like are generally used, and these are roughly classified into two types. One is a benzoin alkyl ether compound represented by benzoin methyl ether or benzoin isopropyl ether, and the second is benzophenones, anthraquinones, benzyls, and acetophenones.

In order to obtain a printing plate having good sensitivity and good image reproducibility, an acetophenone compound having a hydroxyl group or a benzophenone compound is preferred as the photoinitiator (C). These compounds have a feature that they are excellent in ultraviolet transmittance and therefore have a high degree of photocrosslinking at the bottom of the photosensitive layer even at low sensitivity, and can reproduce fine points and fine lines.

The acetophenone compound referred to in the present invention has a skeleton represented by the following chemical structural formula (1).

[0033]

Embedded image (In the formula (1), R represents an aromatic group.) The acetophenone compound preferably has a hydroxyl group in view of the compatibility with the base resin, and has a skeleton of the following chemical structural formula (2). The ones having are preferably used.

[0034]

Embedded image (In the formula (2), R represents an aromatic group.) From the viewpoint of photoinitiation efficiency, those having a molecular weight of 300 or less are preferably used. Such compounds include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Examples include methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone, and the like.

In the present invention, (C) the use of these compounds alone or in combination of two or more of them as the photoinitiator does not impair the effect, and the above compounds and acetophenones having no hydroxyl group, benzoin It may be mixed with alkyl ethers, benzophenones, anthraquinones, benzyls, and diacetyls.

The photoinitiator (C) can be used in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the base resin (A). However, when an acetophenone compound having a molecular weight of 300 or less and having a hydroxyl group in the molecule is used in combination with benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, and diacetyls, the amount of the latter is not more than 300 and 30% by weight based on the acetophenone compound having a hydroxyl group in the molecule
The following are preferred. When the amount exceeds 30% by weight, the storage stability of the composition is reduced due to the effects of benzoin alkyl ethers, benzophenones, anthraquinones, benzyls and diacetyls, and the image reproduction is caused by a decrease in the ultraviolet transmittance of the photosensitive layer. Properties tend to decrease.

In the photosensitive composition of the present invention, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, etc. are used as a compatibilizer between (A) the base resin and (B) the photopolymerizable monomer. Trimethylolethane polyhydric alcohols, p-
It is also possible to add sulfonamides such as toluenesulfonamide and N-butylbenzenesulfonamide. These polyhydric alcohols and sulfonamides have the effect of increasing the flexibility of the photopolymerized portion and preventing the occurrence of relief cracks. Such polyhydric alcohols and sulfonamides are preferably in a range of 30% by weight or less based on the photosensitive layer portion of the photosensitive resin relief printing plate.

In order to increase the thermal stability and storage stability of the photosensitive resin composition of the present invention, a polymerization inhibitor can be used. Preferred thermal polymerization inhibitors include phenols, hydroquinones, catechols and the like. These thermal polymerization inhibitors can be used in the range of 0.001 to 5% by weight based on the photosensitive resin composition.
Further, dyes, pigments, surfactants, defoamers, ultraviolet absorbers, fragrances, and the like can be added.

As the compound (D) which absorbs ultraviolet rays, known compounds can be used arbitrarily, but those which are compatible with (A) the base resin and (B) the photopolymerizable monomer are preferably used.
Further, from the viewpoint of the magnitude of ultraviolet light absorption, a benzophenone-based monomer is more preferably used.

As the benzophenone-based monomer, a compound represented by the following formula (3), that is, a 2-hydroxybenzophenone compound is preferably used.

[0041]

Embedded image (In the formula (3), X represents oxygen or —OR—, Y represents hydrogen or a methyl group, and R represents a linear or branched alkylene group having 1 to 10 carbon atoms or a carbon atom having at least one hydroxyl group. It represents a linear or branched alkylene group of the formulas 1 to 10.)

Specific examples of the 2-hydroxybenzophenone compound represented by the above formula (3) include 2-hydroxy-4-acryloxybenzophenone and 2-hydroxy-benzophenone.
4-methacryloxybenzophenone, 2-hydroxy-
4- (2-acryloxyethoxy) benzophenone, 2
-Hydroxy-4- (2-methacryloxyethoxy) benzophenone, 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone, and the like, but are not limited thereto, and may have the general formula (3) And may have a substituent other than that represented by
Particularly preferred among these are 2-hydroxy-4
-Acryloxybenzophenone, 2-hydroxy-4-
Methacryloxybenzophenone, 2-hydroxy-4-
(2-acryloxyethoxy) benzophenone and 2-hydroxy-4- (2-methacryloxyethoxy) benzophenone.

Other (D) compounds that absorb ultraviolet light include 2- (2H-benzotriazol-2-yl)-
p-cresol, 2-benzotriazol-2-yl-
4,6-di-tert-butylphenol, 2- (4,6-
Diphenyl-1,3,5-triazin-2-yl) -5
-[(Hexyl) oxy] -phenol, octabenzone, and a copolymer containing at least a benzophenone-based monomer and a compound having a hydroxyl group and / or a carboxyl group as a monomer component may also be mentioned. A copolymer containing a monomer and a compound having a hydroxyl group and / or a carboxyl group as a monomer component is preferable.

As the compound having a hydroxyl group and / or a carboxyl group, a known acrylic or methacrylic monomer having a hydroxyl group and / or a carboxyl group can be used. Specific examples include the following (however, acrylate and methacrylate are referred to as (meth) acrylate). Monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, acrylic acid, methacrylic acid , 2- (meta)
Monomers having a carboxyl group such as acryloyloxyethyl succinic acid and 2- (meth) acryloyloxyethyl phthalic acid are exemplified.

Further, as copolymerization components, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate Ester monomers such as acrylate and butoxyethyl (meth) acrylate, diacetone acrylamide, N, N-
Acrylamide-based monomers such as dimethylacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminoethylacrylamide and the like can be copolymerized.

The benzophenone-based monomer and the compound having a hydroxyl group and / or a carboxyl group can be easily copolymerized into a copolymer by a general method such as a radical reaction. Examples thereof include solution polymerization, suspension polymerization, and emulsion polymerization. In particular, solution polymerization is preferred.Toluene, aromatic solvents such as xylene, ethyl acetate, ester solvents such as butyl acetate, methyl ethyl ketone, ketone solvents such as methyl isobutyl ketone, N-butanol,
Alcohol solvents such as propanol, ethanol, and methanol, and water can be used. As the polymerization initiator, peroxides such as benzoyl peroxide and azo compounds such as azobisisobutylnitrile can be used. If necessary, a chain transfer agent such as lauryl mercaptan or octyl thioglycolate can be added.

Further, the ultraviolet transmittance for forming the photosensitive layer (3
(D) at different wavelengths (measured at 65 nm)
In order not to collapse by the migration of the compound that absorbs ultraviolet light,
It is more preferable that at least one layer of the multilayer structure contains a compound that absorbs ultraviolet light having a molecular weight of 10,000 or more, among the compounds (D) that absorb ultraviolet light.

The following method is exemplified as a method for producing the photosensitive resin relief printing plate of the present invention. First, a solution of a necessary kind of a photosensitive resin composition is prepared in order to form a multilayer structure having different ultraviolet transmittances in the photosensitive layer. That is,
After each of the base resin (A) is dissolved by heating in a solvent such as a mixed solvent of water / alcohol, if necessary, an unsaturated epoxy compound is added to carry out an addition reaction. (B)
A photopolymerizable monomer, (C) a photoinitiator and a heat stabilizer are added. Further, if necessary, (D) a substance that absorbs ultraviolet light is added, and the mixture is stirred and sufficiently mixed. In this way, solutions of several kinds of photosensitive resin compositions having different ultraviolet transmittances are obtained.

To form a photosensitive layer having a multilayer structure from the above mixed solution, for example, most of the solvent is distilled out, and then heated to a molten state and extruded on a support to form a first layer. Was melted by the same method as the first layer.
The second layer is formed by extruding the mixed solution for the layer onto the first layer. By repeating this process a required number of times, a photosensitive layer having a multilayer structure can be formed. As another method, a photosensitive layer having a multilayer structure can be formed by preparing a photosensitive sheet of a kind required by a dry film forming method and bonding the required number of sheets on a support. . Further, the first layer is formed by dry film formation directly on the support, and the second layer is formed by dry film formation directly on the first layer in the same manner as the first layer, and this is repeated as necessary. Thus, a photosensitive layer having a multilayer structure can be obtained. Also, using these methods in combination is effective for forming a multilayer structure.

The photosensitive layer is usually formed to a thickness of 0.01 to 10 mm, preferably 0.1 to 2.0 mm.

In order to form a relief image for printing using the photosensitive resin relief printing plate of the present invention, a negative or positive original film is adhered onto the photosensitive layer prepared as described above, and a wavelength of usually 300 to 400 nm is applied. UV light from high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, carbon arc lamps, and chemical lamps, and insolubilized by photopolymerization.

Next, the unpolymerized portion is eluted in water by a spray developing device or a brush developing device using neutral water, whereby a relief is formed on the support to form a printing plate.

The present invention provides a photosensitive resin relief printing plate material excellent in water developability and image reproducibility and useful for producing a printing plate having a sharp relief structure.

This is because the photosensitive layer, which is a molded product of the photosensitive resin composition composed of the base resin and the photoreactive monomer in the present invention, has a multilayer structure having different ultraviolet transmittances, so that the photocuring reaction of each layer can be improved. Therefore, it is presumed that a fine point or a fine line can be reproduced and a sharp relief structure can be obtained.

[0055]

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

<Synthesis Example 1 of Polymeric UV Absorber> The ratios of 2-hydroxy-4-acryloxybenzophenone, 2-hydroxyethyl (meth) acrylate and methacrylic acid were 30 mol%, 20 mol% and 50 mol%. Polymerization was performed to obtain a solution having a solid content of 40% by weight in a solvent having a ratio of 50/50 (weight ratio) of ethanol / water. Measurement with a B-type viscometer (2
The viscosity was 3300 cps at 5 ° C.) and the molecular weight was 12,000 as measured by GPC.

Example 1 Degree of polymerization 650, degree of saponification 75
1 mol% of succinic anhydride was reacted with mol% of partially saponified polyvinyl acetate to cause an addition reaction of a carboxyl group. When the acid value of this modified polyvinyl alcohol was measured, the acid value was 10. The base resin 100 thus obtained
Parts by weight were dissolved in 200 parts by weight of a mixed solvent of ethanol / water = 30/70 (weight ratio) by heating to 80 ° C. Next, 5 parts by weight of glycidyl methacrylate was added, and the mixture was sufficiently stirred to carry out an unsaturated group introduction reaction into the polymer. Analysis by potentiometric titration showed that the carboxyl group added to the side chain of the modified polyvinyl alcohol disappeared and reacted with the epoxy group of glycidyl methacrylate to introduce an unsaturated bond into the side chain of the polymer. Next, 35 parts by weight of an unsaturated epoxy ester compound obtained by an addition reaction of 1 mol of propylene glycol diglycidyl ether and 2 mol of acrylic acid as a photopolymerizable unsaturated compound,
35 parts by weight of hydroxybutyl methacrylate was added and thoroughly stirred. Further, 10 parts by weight of glycerin, 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone as a photoinitiator, 0.2 parts by weight of dimethylbenzyl ketal, and 0.1 part by weight of hydroquinone monomethyl ether to a heat stabilizer were added and sufficiently stirred and mixed.

The photosensitive resin solution obtained in this manner was coated with a polyester adhesive in a thickness of 20 mm.
90 μm after drying on a 0 μm polyester film
The solution was cast so as to have a thickness of 0 μm, and placed in a hot-air oven at 60 ° C. for 5 hours to completely remove the solvent, thereby forming a first layer on the support. The ultraviolet transmittance of the formed photosensitive layer was measured by a spectrophotometer (“U-3300” spectrophotometer manufactured by Hitachi, Ltd.). As a result, the ultraviolet transmittance of the first layer was 100 μm in thickness.
m was 86% for light having a wavelength of 365 nm.

Next, 4 parts by weight of the high-molecular ultraviolet absorber of Synthesis Example 1 was added to the same photosensitive resin solution as in the first layer, and the mixture was sufficiently stirred and mixed. It is cast on top so that the total thickness after drying becomes 950 μm,
In a hot air oven for 2 hours to completely remove the solvent and form a second layer on the support. This second layer has an ultraviolet transmittance of 100 μm in thickness, and has a light transmittance of 42 nm for light having a wavelength of 365 nm.
%Met.

Further, a thin solvent of ethanol / water = 50/50 (weight ratio) is applied to the surface of the photosensitive layer, and a 100 μm-thick polyester film matted by chemical etching is pressed to form a cover film. I attached it. This plate material was stored in a dark place for 10 days. The cover film of the plate material was peeled off, and a gray scale negative film for sensitivity measurement and a negative film for image reproducibility evaluation (175 lines, 1 line)
%, 3%, 5% halftone dots, diameters of 100 μm and 200 μm
(Independent points, with fine lines having widths of 30 μm and 50 μm) were brought into close contact with each other under vacuum and exposed to a chemical lamp for 3 minutes. Then 25
When development was carried out using a brush type developing device containing neutralized water at ℃, the non-image area was completely eluted in water in 2 minutes, and a relief image could be obtained. As a result of evaluating the printing plate thus obtained, it was found that the gray scale remained up to 17 steps, and there was no problem with the high feeling.
When a printing test was performed on the plate material obtained in this manner, such as a 3% halftone dot, a 100 μm independent point, or a 30 μm fine line, a printed material with no thick image and a sharp print was obtained. In addition, printing was performed up to 300,000 sheets, but no problems such as peeling of the relief and generation of cracks occurred.

<Comparative Example 1> Into the composition of the first layer of Example 1, 1 part of the high-molecular ultraviolet absorber of Synthesis Example 1 was added, and the mixture was sufficiently stirred and mixed, and a polyester adhesive was applied in advance. Cast on a 200 μm thick polyester film so that the thickness after drying is 950 μm,
The solvent was completely removed in a hot air oven at 60 ° C. for 5 hours to form a photosensitive layer having a single-layer structure. The ultraviolet transmittance of this photosensitive layer was measured in the same manner as in Example 1, and the thickness was 100 μm.
It was 69% with respect to light having a wavelength of 365 nm.

A cover film was mounted on this photosensitive layer in the same manner as in Example 1 and stored in a dark place for 10 days.

The plate material thus obtained was used as a printing plate in the same manner as in Example 1, and the plate was evaluated. The gray scale remained up to 17 steps, and there was no sensitivity problem.
Also in the printing test, a printed matter with sharp print without thickening of the image was obtained. But 3% of 175 lines
Fine parts such as halftone dots, 100 μm independent points, and 30 μm thin lines could not be reproduced, and reproduction to 5% halftone dots, 200 μm independent points, and 50 μm thin lines was the limit.

Example 2 In the composition of the first layer of Example 1, 2- (5-chloro-2Hbenzotriazol-2-yl) -4,6-bis (1,1- Except that 0.015 parts by weight of (dimethylethyl) phenol was added, the same composition was sufficiently stirred and mixed.
900 μm after drying on μm polyester film
The solution was cast to a thickness of μm and placed in a hot air oven at 60 ° C. for 5 hours to completely remove the solvent, thereby forming a first layer on the support. The ultraviolet transmittance of this photosensitive layer is 100 μm in thickness,
It was 71% with respect to light having a wavelength of 365 nm.

Next, the same photosensitive resin solution as in the first layer of Example 1 was cast on the first layer so that the total thickness after drying was 950 μm, and the solution was placed in a hot air oven at 60 ° C. After a certain time, the solvent was completely removed, and a second layer was formed on the support.
The second layer has an ultraviolet transmittance of 100 μm and a wavelength of 3 μm.
86% for 65 nm light.

Further, after a thin solvent of ethanol / water = 50/50 (weight ratio) was applied to the surface of the photosensitive layer, a 100 μm-thick polyester film matted by chemical etching was pressed to form a cover film. I attached it. This plate material was stored in a dark place for 10 days. A printing plate was prepared from this plate material in the same manner as in Example 1 and evaluated.
The gray scale remained up to 17 steps, and it was found that there was no problem with the high feeling. When a printing test was performed on the plate material obtained in this way, such as a 3% halftone dot, 100 μm independent point, or 30 μm fine line, an image area was obtained. Also,
Printing was performed up to 300,000 sheets, but no problems such as peeling of the relief and generation of cracks occurred.

[0067]

Industrial Applicability According to the present invention, in printing using a photosensitive resin relief printing plate, a photosensitive resin relief printing plate material excellent in water developability and image reproducibility and useful for producing a printing plate having a sharp relief structure. It became possible to provide.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/07 C08K 5/07 C08L 33/14 C08L 33/14 77/00 77/00 G03F 7/004 502 G03F 7/004 502 7/027 501 7/027 501 7/028 7/028 7/032 7/032 7/095 7/095 // C08F 290/08 C08F 290/08 F term (reference) 2H025 AA04 AB02 AC01 AD01 BC13 BC32. PA27 PA69 PB40 PC02 QA03 QA06 QA18 QA32 QA34 QA38 QB06 QB17 QB19 SA02 SA06 SA22 SA34 SA42 SA63 TA02 VA01 WA01 4J027 AA06 AD02 AE04 AJ08 BA08 BA14 BA17 BA19 BA20 CA03 CA29 CB10 CC05 CD08 CD10

Claims (3)

[Claims] 1. A photosensitive resin relief printing plate having at least a support and a photosensitive layer, wherein the photosensitive layer has an ultraviolet transmittance (365n).
A photosensitive resin relief plate material having a multilayer structure composed of layers having different wavelengths (measured at a wavelength of about m and a thickness of about 100 μm). 2. A photosensitive layer comprising at least one of (A) a base resin, (B) a photoinitiator, (C) a photopolymerizable unsaturated compound having an ethylenic double bond in a molecule, and (D) The photosensitive resin relief printing plate according to claim 1, wherein the photosensitive resin relief printing plate comprises a compound that absorbs ultraviolet rays. (D) the compound which absorbs ultraviolet rays has a molecular weight of 1;
The photosensitive resin relief printing plate material according to claim 2, wherein the photosensitive resin relief plate material is not less than 0000.