JPH04301643A - Photosensitive resin composition for flexographic printing plate - Google Patents

Abstract

PURPOSE:To obtain the photosensitive resin composition for forming a water- developable flexographic printing plate using an aqueous ink or other flexographic inks superior in printing resistance. CONSTITUTION:The photosensitive resin composition for forming the flexographic printing plate is characterized by being composed essentially of the resin components comprising (A) an amorphous polyene compound having a number average molecular weight of 500-30000 and a polymer segment of conjugated double bonds and (B) a crystalline polyene compound in an A/B weight ratio of 2-50: and an ethylenically unsaturated compound; and a photopolymerization initiator.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition for flexographic printing plates, and more particularly to a water-developable photosensitive resin composition for flexographic printing plates with improved ink solvent resistance.

0002

[Prior Art] A photosensitive resin composition is prepared by using an elastomer such as chlorinated rubber, styrene-butadiene block copolymer, or polyurethane as a carrier resin component, and disposing an ethylenically unsaturated compound and a photopolymerization initiator thereon. Taking advantage of these characteristics, it is useful as a flexographic printing plate material, and many proposals have been made, for example, as in US Pat. No. 2,948,611, US Pat.

Since such photosensitive resin solid plate materials require halogenated hydrocarbon development and have problems such as health problems and environmental pollution, photosensitive resin solid flexographic printing plates that can be developed with water are used. The development of photosensitive resin solid flexographic printing plate materials that can be developed with water is desired, for example, in Japanese Patent Publication Nos. 42259/1982, 22339/1982, 186232/1983, etc. Proposals regarding resin compositions have been made. However, it is difficult to satisfy all of the printing plate material's raw plate strength, water developability, flexibility as a flexographic printing plate, and compatibility with water-based inks, which are the main inks for flexographic printing. I haven't gotten anything satisfactory. In particular, in the development process, a photosensitive resin solid flexographic printing plate material that has practical developability using only neutral water has not been obtained.

In view of the above problems, the present inventors have developed a photosensitive resin solid plate material that can be developed with water and is resistant to inks containing polar solvents such as water-based or alcoholic solvents. As a result of further investigation into the properties of photosensitive materials, we found that a large amount of photocurable components, which are mainly liquid components, are gelled and solidified using a small amount of a specific resin component and a specific component known as an organic solvent gelling agent to achieve the desired photosensitivity. It was previously proposed that a solid resin printing plate material having a high viscosity can be obtained (for example, JP-A No. 63-278053, JP-A No. 63-287845, etc.).

[0005]

[Problems to be Solved by the Invention] The object of the present invention is to
The object of the present invention is to develop and improve the technology proposed in Publication No. 5, and to provide a photosensitive resin solid plate material that can be particularly water-developable and provides a flexographic printing plate with further improved flexographic ink resistance.

[0006]

[Means for Solving the Problems] The purpose of the present invention is to
A photosensitive resin composition for a flexographic printing plate mainly consisting of a resin component, an ethylenically unsaturated compound component and a photopolymerization initiator, wherein the resin component has a polymer segment of a conjugated diene monomer and has a number average molecular weight of 500 to 3000.
A photosensitive resin composition for a flexographic printing plate, comprising an amorphous polyene compound (A) of 0 and a crystalline polyene compound (B), and having an A/B weight ratio in the range of 2 to 50. This is achieved by

That is, the present inventors solidified or toughened a large amount of ethylenically unsaturated compound with a small amount of a specific resin, which had not been thought of as a solid plate material, and applied this to a photosensitive resin composition. It was discovered that this could result in a photosensitive resin printing plate material that provides printing plates with excellent developability and suitability for a wide range of inks. In order to further improve the printing durability when using certain aqueous or alcohol-based inks, in particular, as a resin component of a photosensitive resin composition, a polymer segment of a conjugated diene monomer having a number average molecular weight of 500 to 30,000 is used. A large amount of the amorphous polyene compound (A) is used, this is used in combination with the crystalline polyene compound (B), and the weight ratio of A/B is selected in the range of 3 to 50. By using a saturated compound component and a photopolymerization initiator as essential components, and using other components as necessary, water-developable flexographic printing has unexpectedly excellent polar ink resistance, flexibility, and printing durability. The present invention was achieved by discovering that a solid photosensitive resin composition capable of forming a plate can be obtained.

The number average molecular weight of the conjugated diene monomer used in the present invention having a polymer segment of 50
Examples of the amorphous polyene compound having a molecular weight of 500 to 30,000 include polybutadiene, which is usually known as liquid rubber and has a number average molecular weight of 500 to 30,000, preferably a number average molecular weight of 500 to 5,000, which has substantially no crystallinity.
00~30000, preferably number average molecular weight 5000~
30,000 polyisoprene, a copolymer with a number average molecular weight of 500 to 30,000 consisting of conjugated diene monomers such as butadiene, isoprene, and pentadiene and olefins, and further utilizing the reactivity of the terminal groups or molecular chains of these polyenes. Examples include modified forms. As a degenerate,
Intramolecular or terminal maleated products, epoxy products, acryloyl or methacryloylated products, etc. are used, and maleated products, acryloyl or methacryloylated products are particularly preferably used. The crystalline polyene compound is a polyene having a crystallinity of 3 to 50%, preferably 10 to 40%, and polybutadiene, polyisoprene, or a copolymer thereof is particularly preferably used. Consistent with the purpose of the present invention, these crystalline polyene compounds preferably have a number average molecular weight of 50,000 to 5,000,000, more preferably 70,000 to 500,000. In addition, the degree of crystallinity in the present invention is defined in Japanese Patent Application Laid-open No. 49-82.
It was determined according to the definition and measurement method described in Publication No. 737.

The conjugated diene monomer used in the present invention has a polymer segment with a number average molecular weight of 50
The amount of the amorphous polyene compound of 0 to 30,000 used is preferably 10 to 80% by weight, more preferably 20 to 70% by weight, even more preferably 35 to 60% by weight based on the total photosensitive resin composition. However, the amount of the crystalline polyene compound used is 0.05% of the total photosensitive resin composition.
It is preferably 2 to 20% by weight, more preferably 1 to 15% by weight, and even more preferably 2 to 10% by weight. The weight ratio of the amorphous polyene compound (A) having a number average molecular weight of 500 to 30,000 and the crystalline polyene compound (B) having a polymer segment of a conjugated diene monomer, that is, the weight ratio of A/B, is preferably 3 to 50. is 4-4
If this weight ratio is smaller than 3, the dissolution and dispersion of the crystalline polyene compound in the composition will be poor, resulting in poor reliability of the resulting flexographic printing plate. - The shape of the flap becomes defective. 50 again
If it is larger than this, the effect of using the crystalline polyene is substantially lost, and the printing durability of the flexographic printing plate, which is the object of the present invention, tends to be insufficient.

The photosensitive resin composition of the present invention is characterized by containing the above resin components, and the ethylenically unsaturated compounds used as other essential components are not particularly limited. No, but one or more hydroxyl or carboxyl groups in the molecule with a boiling point of 150
Acrylates or methacrylates having a temperature of 0.degree. C. or higher, or derivatives of these organic acid anhydrides or amines are preferably used. As the acrylate or methacrylate having one or more hydroxyl group or carboxyl group in the molecule and having a boiling point of 150°C or higher, all known compounds that meet these conditions can be used, but for example, caprolactone-modified 2-hydroxy Ethyl methacrylate or caprolactone-modified 2-hydroxyethyl acrylate (hereinafter both will be abbreviated as caprolactone-modified 2-hydroxyethyl (meth)acrylate. In the following explanation, (meth)acrylate will not be described. acrylate and methacrylate), caprolactone-modified 2-hydroxypropyl (meth)acrylate, and ethylene oxide-modified phthalic acid (meth) such as β-hydroxyethyl β'-acryloyloxyethyl phthalate. ) acrylate, propylene oxide modified phthalic acid (meth)acrylate, 3-phenoxy 2-hydroxypropyl (
meth)acrylate, 3-butoxy 2-hydroxypropyl (meth)acrylate, etc., or alkylene oxide, lactone adducts and acid anhydride adducts to the hydroxyl group of these compounds, such as dicaprolactone-modified 2
-Hydroxyethyl (meth)acrylate, tricaprolactone-modified 2-hydroxyethyl (meth)acrylate, β-hydroxydi(ethyleneoxy)ethyl β'-
acryloyloxyethyl phthalate, and even 2-
Examples include, but are not limited to, hydroxyethyl (meth)acrylate and phthalic anhydride or succinic acid adducts, and salts of (meth)acrylates having a carboxyl group with the above compounds and tertiary amine compounds. It is also possible to use two or more types together.

The photosensitive resin composition of the present invention may optionally contain alkylbenzenesulfonamides, alkylene glycols, glycerin, liquid polyolefins, tertiary amine compounds, and tertiary amine salts of organic carboxylic acids. It is possible to contain a plasticizer component such as.

In the present invention, in order to impart good water developability to the target flexographic printing plate material, the resin component constituting the photosensitive resin composition, the ethylenically unsaturated compound and, if necessary, are added. It is preferable that at least a part of the plasticizer component is a carboxylic acid and/or a carboxylic acid salt, and a tertiary amine salt of an organic carboxylic acid is particularly preferably used. The carboxylic acid component of the carboxylate salt used as at least a part of the resin component is a carboxyl group-introduced polyene compound having a number average molecular weight of 500 to 30,000 having a polymer segment of a conjugated diene monomer, and a carboxylic acid component that is ring-opened. An acid anhydride-introduced product that gives the following is preferably used, and specifically, carboxyl group-terminated polyenes, and intramolecular or terminal maleated polyenes are preferably used.

As the carboxylic acid component of the carboxylic acid or carboxylate salt used as at least a part of the ethylenically unsaturated compound component, as a salt forming product of a tertiary amine compound having one or more ethylenically unsaturated bonds, Although all mono- or polyvalent carboxylic acids can be used, preferred carboxylic acid components that meet the purpose of the present invention include maleic acid, fumaric acid, itaconic acid, mesaconic acid, and adipic acid. , sebacic acid, cyclohexane 1,2-dicarboxylic acid, 4-methylcyclohexane 1,2-dicarboxylic acid, isophthalic acid, 1,2,3,
Polyvalent carboxylic acids such as 4-butanetetracarboxylic acid, or derivatives thereof such as 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-acryloyloxyethyl succinic acid,
- Acryloyl or methacryloyl group-containing compounds such as methacryloyloxyethylsuccinic acid, but are not limited thereto. In addition, among the above carboxylic acid components, carboxylic acid components having one or more ethylenically unsaturated bonds can be used as a salt former of a tertiary amine compound that does not have an ethylenically unsaturated bond. etc. are used.

In the present invention, the carboxylic acid component of the carboxylic acid or carboxylic acid salt used as at least a part of the plasticizer component includes a tertiary amine compound having no ethylenically unsaturated bond and the above carboxylic acid. Among the components used are salts of carboxylic acid components that do not have ethylenically unsaturated bonds. Although alkali metals such as lithium, sodium and calcium can also be used as salt-forming substances for the carboxylate component, amine compounds are preferably used. The amine compound is not particularly limited, but tertiary amines are preferably used, and ethylene is added to the photosensitive resin composition of the present invention in the stock solution preparation process using a primary amine or a secondary amine as a reactive additive component. A method of reacting with acrylates or methacrylates, which are system unsaturated compound components, to form a tertiary amine is particularly preferably used, and the tertiary amine compound produced here is useful as a plasticizer component alone. However, by forming a salt with the carboxylic acid component, a tertiary amine salt functioning as a plasticizer component and a tertiary amine compound or tertiary amine salt functioning as an ethylenically unsaturated compound component can be produced simultaneously.

The structure of the final tertiary amine compound in the photosensitive resin composition of the present invention is a polyvalent amine having one or more hydroxyl groups in the molecule and having a molecular weight of 300 or more, preferably 700 or more. Preferred are isophorone diamine, metaxylylene diamine, triethylene tetramine, diethylene triamine, α,ω-diamino polypropylene glycol, alkyl glycidyl ether adducts from dimer acid amidoamine, and acrylate.
Adducts and the like are preferably used, and their production methods are described in JP-A-63-162660 and JP-A-1-69059.
This method is based on the method shown in the publication.

[0016] At least a part of these tertiary amine compounds is preferably in the form of a carboxylic acid salt in the photosensitive resin composition.

[0017] Such a carboxylic acid salt is preferably used in an amount of 10 to 80% by weight, more preferably 20 to 60% by weight, based on the total photosensitive resin composition.
If it is less than 10% by weight, water developability will be insufficient, and 80% by weight.
If the amount is more than % by weight, the shape retention of the photosensitive resin composition will be insufficient.

[0018] In order to make the flexographic printing plate material obtained from the photosensitive resin composition of the present invention practical in retaining the green plate shape, it is preferable to use a gelling agent, and as such a gelling agent, is added to a composition consisting of a resin component, an ethylene compound, and, if necessary, a plasticizer component.
It is a compound that dissolves at a temperature of 0°C or higher and has the ability to solidify the composition at room temperature. Such gelling agents are known as polymeric gelling agents or oil gelling agents, and various types of gelling agents are used. Compounds that have a gelling ability even with organic solvents (hereinafter, compounds known as oil gelling agents in contrast to polymeric gelling agents will be simply abbreviated as gelling agents) are mentioned.

As the polymeric gelling agent, a partially crystalline polymer can be used, and crystalline polyenes, which are an essential component of the present invention, also fall under this category, but other partially crystalline polymers can be used. molecules can also be used, and number average molecular weight 100
Polymers having functional groups or bonds that form strong intermolecular hydrogen bonds such as amide bonds, hydroxyl groups, and carboxyl groups in molecules of 00 or more can also be used. Such polymeric gelling agents are not particularly limited, but copolyamides, particularly polyetheresteramides or polyetheramides having polyethylene oxide segments, are suitable for the purpose of the present invention. Preferably used.

The amount of polymeric gelling agent other than crystalline polyenes used is preferably 10% by weight or less, more preferably 5% by weight or less based on the total photosensitive resin composition. .

The gelling agent component used in the present invention is preferably at least one member selected from the group of 12-hydroxystearic acid, benzylidene sorbitols, benzylidene xylitols, and N-acylamino acid derivatives. are used, specifically 1,3:2,4-dibenzylidene sorbitol, 1,3:2,4:5,6-
tribenzylidene sorbitol, 1,3:2,4-p-
p'-ditolylidene sorbitol, 1,3:2,4-
p-p'-diethylbenzylidene sorbitol, 1,3
:2,4-dibenzylidenexylitol, N-lauroyl-L-glutamic acid-α, γ-di-n-butylamide, etc. are representative compounds, but are not limited to these. A wide variety of gelling agents can be used, such as those described in Patent No. 4,927,739.

The amount of these gelling agent components to be used is preferably in the range of 0.1 to 20% by weight based on the total photosensitive resin composition, and if the amount is less than 0.1% by weight, The intended shape retention of the flexographic printing plate material becomes insufficient, and if the amount is more than 20% by weight, the printing plate obtained tends to have poor printing durability.

[0023] The polymeric gelling agent and the gelling agent can each be used alone, but it is preferable to use them in combination.

As the photopolymerization initiator for rapidly photopolymerizing the composition of the present invention, all conventionally known compounds can be used. Examples include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. These photopolymerization initiators are 0% based on the total photosensitive resin composition.
．． It can be used in a range of 0.01 to 10% by weight. Further, in order to increase the thermal stability of the photosensitive resin composition of the present invention, all conventionally known polymerization inhibitors can be used. Preferred polymerization inhibitors include phenols, hydroquinones, catechols, and phenothiazine. These heat stabilizers can be used in an amount of 0.001 to 5% by weight based on the total composition. Dyes as other additives,
Pigments, surfactants, antifoaming agents, ultraviolet absorbers, fragrances, etc. can be added.

In particular, it is effective to use surfactants as components of the photosensitive resin composition of the present invention, such as carboxylated polyoxyethylene higher alkyl ethers or their tertiary amine salts, alkali metal salts of higher alkyl sulfates, The use of alkali metal salts of higher alkyl phosphoric acids, higher alkyl ammonium salts, etc. makes the intended relief image of the flexo plate clearer. The amount of these surfactants used is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight based on the total photosensitive resin composition.

[0026] As another additive, the use of a compound having one or more tertiary amine bonds and one or more hydroxyl group in the molecule in the composition of the present invention improves the molding processability and the properties of the molded product. The addition of such compounds improves the stability during the preparation of the photosensitive resin composition of the present invention, and also improves the image of the printing plate obtained from the photosensitive resin composition of the present invention. It is something. Among such amine additives, molecular weights of 300 to 3000 are particularly important.
, and more preferably 700 to 2000 compounds. When using such an amine additive, a method of adding an active hydrogen-containing amine to form a tertiary amine during composition preparation can also be adopted.

As a method for producing the photosensitive resin composition of the present invention, first, a resin component is added to an ethylenically unsaturated compound mixed with liquid components such as a heat stabilizer and a plasticizer, and the mixture is heated to a temperature of 70 to 100% while stirring. After heating to 200° C., preferably 100 to 180° C. to dissolve the resin component, a photopolymerization initiator and other additive components are mixed and dissolved to produce a substantially solvent-free solution. A reactive plasticizer component may be added at this stage. This solution can be cast or cast and cooled to directly obtain a molded product. The photosensitive resin composition of the present invention is characterized by being substantially a thermoreversible gel, and is a solid with practical strength at room temperature, but becomes a relatively low-viscosity liquid when heated. Therefore, an easy molding method that takes advantage of this property can be applied. The photosensitive resin composition of the present invention can be designed to become a liquid with a temperature of 100 poise or less at 150°C, and further, a liquid with a temperature of 100 poise or less at 120°C.

[0028] In order to form a printing plate material using the photosensitive resin composition of the present invention, for example, a solution of the present composition may be directly cast onto a support or a cover film. Can be done. If necessary, dry film forming may be performed if a solvent is used, but since molding is usually done without a solvent, photosensitive resin sheets can be produced by cooling only, and thick films can be formed. It is also easy to mold. Generally, it is preferable to form a thin film layer mainly composed of water-soluble or dispersible resin on the upper surface of the photosensitive resin sheet in order to improve the adhesion with the negative film.

As the support, a metal plate made of steel, stainless steel, aluminum, copper, etc., which has an adhesive layer as required, a plastic sheet such as a polyester film, a synthetic rubber sheet, etc. is used, and the photosensitive layer is usually 0.
It is formed to a thickness of 1 to 10 mm.

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 closely adhered to the photosensitive layer prepared as described above, and a film of usually 300 to 450 mμ is formed. UV rays from high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, chemical lamps, carbonark lamps, etc. are irradiated with wavelengths at the center, and curing occurs through a photoreaction. A relief is then formed on the support by dissolving or dispersing the uncured portion in water using a spray or brush developing device.

After drying this, a flexographic printing plate can be obtained by treating it with actinic rays in the air or in a vacuum.

The photosensitive resin composition of the present invention has the characteristic that it contains an elastomer component that could not be used as a water-developable printing plate material in the past, so it can improve printing durability in printing using various flexographic inks. This is a water-developable flexographic printing plate.

[0033]

[Examples] The present invention will be explained in detail below with reference to Examples.

Note that the parts used in the following examples are parts by weight, and unless otherwise specified, the number average molecular weight is a value determined by a combination of viscosity measurement method and GPC method, and for high molecular weight products, It relies on ultracentrifugation.

Synthesis Example 1 A copolyamide containing the following components was synthesized based on a known recipe (for example, JP-A-55-79437).

ε-caprolactam/Equimolar salt of hexamethylene diamine and adipic acid/Equimolar salt of α,ω-diaminopropylpolyoxyethylene (number average molecular weight 1000) and adipic acid=20/20/60 Obtained here When the terminal groups of the copolyamide were quantified, the primary amino groups were 4.0 x 10-5 mol/g, and the carboxyl groups were 2.1 x 10-5 mol/g, and the number average molecular weight according to the terminal group quantitative method was approximately It was 33,000.

Synthesis Example 2 1 mol and 2 mol of isophorone diamine as additive components
-Ethylhexylglycidyl ether 1 mol of adduct (reacted at 70°C for 3 hours) was synthesized.

Example 1 M2000-20(
(manufactured by Nippon Petrochemical Co., Ltd.) 20 parts, number average molecular weight 3000
M3000-20 (manufactured by Nippon Petrochemical Co., Ltd.) 2, which is an adduct of 1 mol of maleic anhydride to 1 mol of polybutadiene
5 parts, crystallinity 15%, 1,2-bond structure 88%, number average molecular weight 110,000 crystalline polybutadiene "JSR
"RB810 (manufactured by Japan Synthetic Rubber Co., Ltd.) 10 parts, β-hydroxyethyl β'-acryloyloxyethyl phthalate 35 parts, 2-acryloyloxyethyl phthalate 2
1 part, heat stabilizer hydroquinone 0.1 part, and carboxylated tetra(oxyethylene) lauryl ether 3 parts, heated, heated, stirred at 105 ° C. for 1 hour, and then added as shown in Synthesis Example 2. Add 5 parts of agent and further heat to 140°C.
After stirring for 1 hour, 1.5 parts of benzyl dimethyl ketal was added as a photopolymerization initiator, 5 parts of dibenzylidene sorbitol, and N-lauroyl-L- as other additive components.
5 parts of glutamic acid-α·γ-di-n-butylamide was added and dissolved. The solution obtained in this way was coated with a polyester adhesive and cured in advance to a thickness of 10 mm.
The thickness of the photosensitive layer is 1700 μm on a 0μ polyester substrate.
A solid photosensitive resin printing plate material was obtained by casting, coating, and standing at room temperature so that the particle diameter was μ. On the photosensitive layer of this printing plate material, a gray scale negative film for sensitivity measurement (Stouffe
Manufactured by r company, 21Steps Sensitivity G
uide) and negative film for image reproducibility evaluation 150
Line 3%, 5%, 10% halftone dots, diameter 200μ, and 30
0μ independent points, widths of 50 and 70μ thin lines) were placed in vacuum contact and exposed for 3 minutes from a distance of 1 m using a 2KW ultra-high pressure mercury lamp.

After the exposure was completed, development was carried out using a brush-type washing machine (liquid temperature: 35° C.) containing neutral water. Development time 10
A relief image with a depth of 1000 μm was formed in minutes. As a result of evaluating this relief image, it was found that up to 14 steps remained in the grayscale area, and that the image area had almost perfectly reproduced 5% halftone dots, 300μ independent points, 50μ fine lines, etc. The hardness of the printing plate was 60 Shore A hardness after the post-exposure to actinic light. Using this printing plate, a 100,000-sheet flexographic printing test using water-based ink was conducted, and good printed matter was obtained.

Comparative Example 1 A photosensitive resin printing plate was obtained in the same manner as in Example 1 except that the amount of β-hydroxyethyl β'-acryloyloxyethyl phthalate used was 45 parts, but without using "JSR" RB810. When a printing test similar to that in Example 1 was carried out, the printing plate was found to have minute portions chipped.

Example 2 M2000-20(
(manufactured by Nippon Petrochemical Co., Ltd.) 20 parts, number average molecular weight 3000
M3000-20 (manufactured by Nippon Petrochemical Co., Ltd.) 3, which is an adduct of 1 mol of maleic anhydride to 1 mol of polybutadiene
0 parts, crystallinity 15%, 1,2-bond structure 88%, number average molecular weight 110,000 crystalline polybutadiene "JSR
7 parts of RB810 (manufactured by Japan Synthetic Rubber Co., Ltd.), 28 parts of β-hydroxyethyl β'-acryloyloxyethyl phthalate, 0.05 part of heat stabilizer hydroquinone, 2 parts of 2-acryloyloxyethyl hexahydrophthalic acid, 1
3 parts of 2-hydroxystearic acid and 3 parts of the polyether amide obtained in Synthesis Example 1 as a polymeric gelling agent were mixed, heated, heated, and stirred at 105°C for 1 hour, then Synthesis Example 2 After adding 7 parts of the additive shown in , and stirring at 140°C for 1 hour, 1.5 parts of benzyl dimethyl ketal as a photopolymerization initiator, 4 parts of dibenzylidene sorbitol, and N-lauroyl as other additive components. 3 parts of L-glutamic acid-α·γ-di-n-butylamide was added and dissolved. The solution obtained in this manner was cast, applied, and left at room temperature on a 100 μm thick polyester substrate on which a polyester adhesive had been applied and cured in advance so that the photosensitive layer had a thickness of 1700 μm. A solid photosensitive resin printing plate material was obtained. On the photosensitive layer of this printing plate material, a grayscale negative film for sensitivity measurement (manufactured by Stouffer,
21Steps Sensitivity Gui
de) and negative film 150 lines 3 for image reproducibility evaluation
%, 5%, 10% halftone dot, diameter 200μ, and 300μ
(Independent point, width 50 and 70 μ thin line) are vacuum-adhered, and 15cm
It was exposed for 10 minutes from a distance of m.

After the exposure was completed, development was carried out using a brush-type washing machine (liquid temperature: 30° C.) containing neutral water. A relief image with a depth of 1000 μm was formed in a development time of 5 minutes. As a result of evaluating this relief image, it was found that up to 15 steps remained in the gray scale part, and the image part had 5% halftone dots, 300μ independent points,
It was found that 50μ thin lines and the like were almost completely reproduced. The hardness of the printing plate is Shore A after post-exposure to actinic light.
The hardness was 48. Using this printing plate, a 200,000-sheet flexographic printing test using water-based ink was conducted, and good printed matter was obtained.

Comparative Example 2 In Example 2, the amount of β-hydroxyethyl β'-acryloyloxyethyl phthalate used was 58 parts, the amount of M2000-20 used was 5 parts, and the amount of M3000-20 used was 58 parts.
A photosensitive resin printing plate material was obtained in the same manner using 5 parts, but the relief of the printing plate obtained from this printing plate material was 1 part.
It contained many particles with a size of 00 μm or more, and the unevenness caused by these particles was severe and non-uniform, making it impractical.

Example 3 40 parts of polyisoprene "Kuraprene" LIR-30 (manufactured by Kuraray Co., Ltd.) having a number average molecular weight of 15,000, crystallinity 2
5 parts of 0% trans-1,4 polyisoprene (number average molecular weight 350,000), 1 part of maleic anhydride, 35 parts of β-hydroxyethyl β'-acryloyloxyethyl phthalate, 0.05 part of heat stabilizer hydroquinone, 2- 3 parts of acryloyloxyethylhexahydrophthalic acid, 3 parts of carboxylated tetra(oxyethylene) lauryl ether, and 3 parts of the polyether amide obtained in Synthesis Example 1 as a polymeric gelling agent were mixed, heated, and heated. After stirring at 105°C for 1 hour, 7 parts of the additive shown in Synthesis Example 2 were added, and after stirring at 140°C for 1 hour, 1.5 parts of benzyl dimethyl ketal as a photopolymerization initiator and others were added. As additive components, 4 parts of dibenzylidene sorbitol, N
-Lauroyl-L-glutamic acid-α,γ-di-n-butylamide (3 parts) was added and dissolved. The solution obtained in this manner was cast, applied, and left at room temperature on a 100 μm thick polyester substrate on which a polyester adhesive had been applied and cured in advance so that the photosensitive layer had a thickness of 1700 μm. A solid photosensitive resin printing plate material was obtained.

A flexographic printing plate was obtained from this photosensitive resin printing plate material in the same manner as in Example 2.

Example 4 In Example 2, the amount of β-hydroxyethyl β'-acryloyloxyethyl phthalate used was reduced to 18 parts, and 10 parts of caprolactone-modified 2-hydroxyethyl methacrylate was used instead. A flexographic printing plate having similarly excellent printing durability was also obtained.

Example 5 M2000-20(
(manufactured by Nippon Petrochemical Co., Ltd.) 20 parts, number average molecular weight 3000
M3000-20 (manufactured by Nippon Petrochemical Co., Ltd.) 2, which is an adduct of 1 mol of maleic anhydride to 1 mol of polybutadiene
0 parts, crystallinity 15%, 1,2-bond structure 88%, number average molecular weight 110,000 crystalline polybutadiene "JSR
10 parts of RB810 (manufactured by Nippon Gosei Rubber Co., Ltd.), 28 parts of β-hydroxyethyl β'-acryloyloxyethyl phthalate, 0.05 part of heat stabilizer hydroquinone, 15 parts of caprolactone-modified 2-hydroxyethyl methacrylate. , 5 parts of the polyetheramide obtained in Synthesis Example 1 as a polymeric gelling agent was mixed, heated, and heated to 105°C.
After stirring for 1 hour at 140°C, 5 parts of the additive shown in Synthesis Example 2 were added, and after stirring at 140°C for 1 hour, 1.5 parts of benzyl dimethyl ketal as a photopolymerization initiator and other additives were added. Ingredients: 3 parts of carboxylated tetra(oxyethylene) lauryl ether, 3 parts of dibenzylidene sorbitol, N-lauroyl-L-glutamic acid-α/γ
- 3 parts of di-n-butylamide was added and dissolved. The solution obtained in this way was cast onto a 100 μm thick polyester substrate on which a polyester adhesive had been applied and cured in advance so that the photosensitive layer had a thickness of 1700 μm.
The coating was applied and left at room temperature to obtain a solid photosensitive resin printing plate material. A grayscale negative film for sensitivity measurement (manufactured by Stouffer, 21Step) was placed on the photosensitive layer of this printing plate material.
s Sensitivity Guide) and negative film for image reproducibility evaluation 150 lines 3%, 5%, 1
0% halftone dot, diameter 200μ, and 300μ independent dot, width 5
(0 and 70μ thin wires) were placed in vacuum contact and exposed for 10 minutes from a distance of 15 cm using an exposure device equipped with 15 20W chemical lamps.

After the exposure, development was carried out using a brush type washing machine (liquid temperature: 30° C.) containing neutral water. A relief image with a depth of 700 μm was formed in a development time of 10 minutes. As a result of evaluating this relief image, it was found that up to 13 steps remain in the gray scale part, and in the image part, 10% halftone dots, 300μ independent points, 50μ thin lines, etc. are almost completely reproduced. The hardness of the printing plate was 58 Shore A hardness after post-exposure to actinic light. Using this printing plate, we conducted a 100,000-sheet flexographic printing test using water-based ink.
Good prints were obtained.

[0049]

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to provide a photosensitive resin composition that provides a water-developable flexographic printing plate with excellent printing resistance in flexographic printing using water-based ink or other flexographic ink. That is.

Claims (4)

[Claims] Claims 1. A photosensitive resin composition for flexographic printing plates mainly comprising a resin component, an ethylenically unsaturated compound component, and a photopolymerization initiator, wherein the resin component has a number average polymer segment of a conjugated diene monomer. Molecular weight 50
A photosensitive resin for flexographic printing plates, comprising an amorphous polyene compound (A) of 0 to 30,000 and a crystalline polyene compound (B), and having an A/B weight ratio of 3 to 50. Composition. 2. The photosensitive resin composition for a flexographic printing plate according to claim 1, wherein the photosensitive resin composition contains a carboxyl group and/or an organic carboxylate structure. 3. The photosensitive resin composition comprises at least one gelling agent selected from the group of 12-hydroxystearic acid, benzylidene sorbitols, benzylidene xylitols, N-acylamino acid derivatives, and polyamides. The photosensitive resin composition for flexographic printing plates according to claim 1, characterized in that it contains: 4. The photosensitive resin composition is selected from the group consisting of carboxylated polyoxyethylene higher alkyl ethers or their tertiary amine salts, alkali metal salts of higher alkyl sulfuric acids, alkali metal salts of higher alkyl phosphoric acids, and higher alkyl ammonium salts. The photosensitive resin composition for flexographic printing plates according to claim 1, characterized in that it contains at least one selected surfactant.