JPH07333830A - Photosensitive resin composition for printing plate and photosensitive resin plate material - Google Patents

Abstract

PURPOSE:To obtain a photosensitive resin compsn. for a flexographic printing plate having good water developing property and sufficient adaptability to water-base ink by incorporating a hydrophilic polymer, rubber, specified photopolymerizable unsatd. compd., and a photopolymn. initiator. CONSTITUTION:This photosensitive resin compsn. for a printing plate contains a hydrophilic polymer, rubber having >=40000mol.wt., photopolymerizable unsatd. compd. having ethylene-type double bonds in the molecule, and a photopolymn. initiator. As for the hydrophilic polymer, polyamide is preferably used. The rubber having >=40000mol.wt. is not specified but any rubber except for a liquid rubber can be used. The amt. of the hydrophilic polymer used is preferably 3 to 4wt.% of the compsn., and the amt. of rubber used is preferably 10 to 80wt.% of the compsn. As for the photopolymerizable unsatd. compd. having ethylene-type double bonds, any well-known material having polymerizable property by addition polymn. can be used. The amt. of the compd. in the compsn. is preferably 10 to 80wt.%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photosensitive resin composition for a printing plate, and more particularly to a printing plate suitable for water-developable flexographic printing in which the printing durability of the printing plate is improved. The present invention relates to a photosensitive resin composition.

[0002]

2. Description of the Related Art A photosensitive resin composition comprising an elastomer such as chlorinated rubber, styrene-butadiene block copolymer and polyurethane as a carrier resin component and an ethylenically unsaturated compound and a photopolymerization initiator is an elastomer. It is useful as a flexographic printing plate material by making use of the characteristics of No. 1, and many proposals have been made such as US Pat. Nos. 2,948,611, 3,024,180 and JP-B-51-43374.

Such a photosensitive resin solid plate material requires development with a halogenated hydrocarbon, which causes health problems.
It had problems such as environmental pollution. Therefore, development of a photosensitive resin solid flexographic printing plate material that can be developed with water is desired. For example, JP-B-62-42259 and JP-A-61-2.
2339, JP-A-63-186232, and JP-A-5-160451 propose a photosensitive resin composition for providing a water-developable photosensitive resin solid flexographic printing plate material.

[0004] However, the materials proposed by these are the raw plate strength and water developability of the printing plate material, the flexibility of the flexographic printing plate, and the aqueous ink which is the main ink for flexographic printing. It is difficult to satisfy all of the suitability of, but it is not practically satisfactory. In particular, in the developing step, a photosensitive resin solid flexographic printing plate material having practical developability with substantially only neutral water has not been obtained.

[0005]

SUMMARY OF THE INVENTION The present invention was devised in view of the above-mentioned drawbacks of the prior art, and its object is to have a high degree of image reproducibility and flexibility as a flexographic printing plate, and It is an object of the present invention to provide a photosensitive resin composition for flexographic printing plates, which has good water developability and can satisfy compatibility with aqueous ink.

[0006]

The object of the present invention is as follows.
It is achieved by a photosensitive resin composition for a printing plate containing the following components A, B, C and D. A: hydrophilic polymer B: rubber having a molecular weight of 40,000 or more C: photopolymerizable unsaturated compound having an ethylenic double bond in the molecule D: photopolymerization initiator or A: hydrophilic polymer B: solid rubber C: molecule Unsaturated compound having ethylenic double bond in the polymer D: Photoinitiator

"Hydrophilicity", which is characterized by the component A of the present invention, refers to the property of being dissolved and / or dispersed in water. For example, a film-shaped polymer is immersed in water or warm water and rubbed with a brush or the like. In this case, the film is reduced or disintegrated when the polymer is entirely or partially eluted, or when the polymer is swollen and dispersed and dispersed in water. For the purposes of the present invention,
As a film having a thickness of 0.5 mm, a film which can be dissolved by being immersed in water at 25 ° C. for 1 hour or which can swell 200% by weight or more of water with respect to the polymer without being dissolved is preferably used.

Examples of such hydrophilic polymers include polymers soluble in alcohol and / or water, such as polyamide, partially saponified polyvinyl acetate, and celluloses. Polyamide is preferably used in the present invention from the viewpoints of the compatibility with the above, the compatibility between the hydrophilic polymer and the photopolymerizable unsaturated compound, and the printing durability of the printing plate obtained.

The present invention has found a photosensitive resin composition which can be developed with neutral water and can be applied to printing with an aqueous ink by utilizing the property peculiar to a hydrophilic polymer.

As the hydrophilic polyamide used in the present invention, a polyamide having a sulfonic acid group or a sulfonate group in a side chain, a polyamide having an ether bond in the molecule, a polyamide having a piperidine skeleton and an amino group in a side chain. Either of the polyamides is preferred.

As a polyamide having a sulfonic acid group or a sulfonate group in its side chain, there is known Japanese Patent Application Laid-Open No. 48-72250.
As disclosed in the publication, sulfonic acid obtained by copolymerizing sodium 3,5-dicarboxybenzene sulfonate and the like with an ordinary polyamide raw material, for example, lactam, aminocarboxylic acid, diamine, dicarboxylic acid. Examples include polyamides containing groups or sulfonate groups. As the polyamide having an ether bond in the molecule, a polyamide obtained by copolymerizing at least any one of a dicarboxylic acid, a diamine, an aminocarboxylic acid and a lactam having an ether bond in the molecule, and JP-A-55 An example is a copolymerized polyamide containing a polyalkylene ether segment proposed in Japanese Patent Publication No. 74537. As the polyamide having a piperidine skeleton, N, N'-di (γ-aminopropyl) piperazine as disclosed in JP-A-50-7605 and, if necessary, dicarboxylic acid, diamine, aminocarboxylic The polyamide obtained by (co) polymerizing with an acid and a lactam is illustrated. Further, as the polyamide having an amino group in the side chain, a tertiary one having an amino group in the side chain is preferably used, and a ring-opening polymer of α- (N, N′-dialkylamino) -ε-caprolactam or α- (N, N′-dialkylamino)- A polyamide obtained by copolymerizing (N, N′-dialkylamino) -ε-caprolactam with at least one of a diamine, an aminocarboxylic acid and a lactam is exemplified. Further, in the polyamide having a piperazine skeleton and the polyamide having an amino group in a side chain, those obtained by quaternizing the nitrogen atom with acrylic acid or the like can also be used.

Among these hydrophilic polyamides, those having an ether bond in the molecule are preferably used, and those having an ether bond in the polyalkylene ether segment are preferably used.
The polyalkylene ether segment having a molecular weight of 150 to 1500 is more preferably used.
As a concrete structure of polyamide, an amino group is present at the terminal and the molecular weight of the polyether segment is 150 to 1
30 to 70% by weight of a constitutional unit composed of polyoxyethylene of 500 and an aliphatic dicarboxylic acid or diamine
The copolyamide to be contained is preferably used.

These hydrophilic polymers may be used alone or in combination of two or more.

The rubber or solid rubber having a molecular weight of 40,000 or more which is the component B of the present invention is not particularly limited, and rubbers other than so-called liquid rubber can be used.

The molecular weight of rubber as used herein means the number average molecular weight.

Examples of such rubber include high molecular weight isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, epichlorohydrin rubber, silicone rubber, etc. −
Butadiene copolymer, styrene-isoprene copolymer,
Examples thereof include copolymers of dienes such as butadiene-acrylic acid copolymer, copolymers of olefins such as ethylene-propylene copolymer and ethylene-vinyl acetate copolymer. Among them, a polymer of a diene or a copolymer of an olefin is preferably used from the viewpoint of water-based ink resistance of the obtained printing plate.

In order to achieve both the water developability of the printing plate material and the compatibility of the printing plate with the water-based ink, it is necessary that the rubber is dispersed in an independent form in the photosensitive resin composition of the present invention. preferable. As a method of dispersing the rubber in the photosensitive resin composition, a method of performing a step of melting and mixing the hydrophilic polymer and the rubber to form a molten mixture is preferably used. Melt mixing means that two or more polymers are usually mixed at a temperature above their softening point. The melt mixing allows the rubber particles to be dispersed in a fine size throughout the continuous polymer matrix. The melt-mixing may be carried out using an ordinary masticating device such as a Banbury mixer, a Brabender mixer, a kneader, or a twin-screw extruder. The temperature of melt mixing is preferably in the range of 100 to 250 ° C.

In the photosensitive resin composition of the present invention, the mixing ratio of the hydrophilic polymer and the rubber is 1: 9 to 8 as a weight ratio.
Pair 2 is preferable, and more preferably 1 to 9 to 5: 5. If the compounding amount of rubber is small, a problem of lacking flexibility occurs in the flexographic printing plate which is the object of the present invention. On the other hand, if the compounding amount is large, the problem of poor developability in neutral water occurs. Because there is.

The amount of the hydrophilic polymer used is preferably 3 to 40% by weight, more preferably 5 to 20% by weight, based on the total photosensitive resin composition. This is because if it is less than 3% by weight, the developability is lowered, and the form retention in the raw plate when it is used as a photosensitive resin plate material is lowered. 40% by weight
When it is more than the above range, the water resistance of the printing plate is lowered, and the printing plate is likely to swell with water-based ink, and the printing durability is apt to be deteriorated.

The amount of rubber used is 1 in the total photosensitive resin composition.
The amount is preferably 0 to 80% by weight, more preferably 30 to 70% by weight. Here, the rubber may be blended in the form of rubber particles such as a rubber emulsion or a rubber latex when the photosensitive resin composition is prepared, in addition to the rubber blended in the melt mixture. When the amount of rubber is less than 10% by weight, the flexibility of the printing plate is lowered, and when it is more than 80% by weight, the developability is lowered.

The total amount of the hydrophilic polymer as the component A and the rubber as the component B is preferably 20 to 90% by weight, more preferably 50 to 80% by weight in the total photosensitive resin composition.
Is. When the amount is less than 20% by weight, the obtained plate surface has a large tackiness, and the shape retention of the raw plate when used as a photosensitive resin plate material is impaired. If it is more than 90% by weight, the photosensitive properties of the plate, especially the image reproducibility are deteriorated.

The photopolymerizable unsaturated compound having an ethylenic double bond in the molecule which is the component C of the present invention has a property that it can be polymerized by addition polymerization. As such a material, a known material can be used, and a material having a certain degree of compatibility with the hydrophilic polymer is preferable.

Specifically, the following may be mentioned. 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2
-Monoacrylates and monomethacrylates having hydroxyl groups such as hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate. Polyhydric acrylates and polyhydric methacrylates obtained by reacting polyhydric alcohols such as ethylene glycol with unsaturated carboxylic acids such as acrylic acid or methacrylic acid. Unsaturated epoxy compounds such as glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, and 3,4-epoxycyclohexyl methacrylate. A polyvalent acrylate and a polyvalent methacrylate having a hydroxyl group, which is synthesized by the reaction of a polyvalent glycidyl ether such as ethylene glycol diglycidyl ether and an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. A polyvalent acrylate and a polyvalent methacrylate having a hydroxyl group, which is 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, methylene bis acrylamide, N-methylol acrylamide or polyvalent acrylamide obtained by condensation reaction of N-methylol methacrylamide and polyhydric alcohol and polyvalent Acrylamide-based photopolymerizable monomers such as methacrylamide, and acrylic or methacrylic acid esters having a hydroxyl group and acrylic or methacrylamides are preferably used.

The proportion of the photopolymerizable unsaturated compound in the photosensitive resin composition is preferably in the range of 10 to 80% by weight. It is more preferably 10 to 60% by weight. The proportion of the photopolymerizable unsaturated compound in the photosensitive resin composition is 10% by weight.
If it is less than 3, the density of the cross-linked structure generated by photopolymerization is insufficient, so that it easily swells in a diluting solvent of a water-based ink containing water as a main component, causing swelling destruction of a solid portion during printing and printing failure. It will be easier. Moreover, the crosslinking density is not sufficiently achieved even by exposure, and desired image reproducibility cannot be obtained.

On the other hand, when the proportion of the photopolymerizable unsaturated compound in the photosensitive resin composition exceeds 80% by weight, the density of the crosslinked structure produced by photopolymerization becomes excessive, so that the relief produced by plate making becomes very large. It becomes brittle, which causes problems such as cracking of the relief during printing.

The photopolymerization initiator which is the D component in the present invention is a polymerization of a photopolymerizable unsaturated compound having an ethylenic double bond in the molecule which is the C component by irradiation with electromagnetic waves such as visible light and ultraviolet rays. What can be started. Usually, a radical generator is used, and examples thereof include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. These photopolymerization initiators can be used in the range of 0.01 to 10% by weight based on the total amount of the photosensitive resin composition.

In the photosensitive resin composition of the present invention, a multi-agent such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane or trimethylolethane is added as a compatibilizing agent of the hydrophilic polymer and the photopolymerizable unsaturated compound. Polyhydric alcohols, N-ethyl-p
-Toluenesulfonamide, N-butylbenzenesulfonamide, N-methylbenzenesulfonamide and the like can be added. These polyhydric alcohols,
The sulfonamide-based compound has the effect of further increasing the flexibility of the portion cured by photopolymerization and preventing the occurrence of relief cracks. Such polyhydric alcohols,
The sulfonamide compound is 3 with respect to the photosensitive resin composition.
It can be used in the range of 0% by weight or less.

In order to improve the stability of the photosensitive resin composition of the present invention against heat during production or storage, a conventionally known 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 total amount of the composition. In addition to these additives, dyes, pigments, surfactants, defoamers, ultraviolet absorbers,
Fragrances and the like can be added.

The following method is preferably used as a method for producing the photosensitive resin composition of the present invention. First, as described above, a melted mixture of the hydrophilic polymer as the component A and the rubber as the component B is prepared. Other C component and D component are further mixed with the molten mixture to obtain the photosensitive resin composition of the present invention. The components C and D may be added at the same time or any of them may be added first.

As a method for mixing the molten mixture with other components, for example, a molten mixture of hydrophilic polymer and rubber is dissolved in a mixed solvent such as water / alcohol while heating. By this step, a part or all of the hydrophilic polymer is dissolved, and the microscopically dispersed rubber is dispersed in the solvent. If necessary, an unsaturated epoxy compound is added to this solution to cause an addition reaction with the polymer. Further, a photopolymerizable unsaturated compound, a photopolymerization initiator, and, if necessary, a heat stabilizer are added, and the mixture is stirred and sufficiently mixed to obtain a solution composed of the photosensitive resin composition for a printing plate. .

An unsaturated epoxy compound is added to a solution of a molten mixture of a hydrophilic polymer and a rubber, and the unsaturated epoxy compound is added to a terminal carboxyl group of the hydrophilic polymer and the rubber, thereby photopolymerizing the polymer and the rubber itself. The resulting relief polymer network formed by a photopolymerization reaction with a photopolymerizable compound has a higher density, and the resulting relief has good water resistance and can maintain high image reproducibility. In addition, since the relief is tough, problems such as cracking during printing can be prevented.

A solution of the above-mentioned photosensitive resin composition for a printing plate is applied as a photosensitive layer on a support to obtain a photosensitive resin plate material. In order to form the photosensitive layer, for example, most of the solvent is distilled off, and then the solvent is heated to a molten state and extruded onto a support to form the photosensitive layer. In addition, it is also possible to form a photosensitive sheet by a dry film forming method and adhere the sheet to a support to form a photosensitive layer. Alternatively, a photosensitive layer can be obtained by directly performing dry film formation on a support. 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 is used. The photosensitive layer is
It is preferably formed to a thickness of 0.01 to 10 mm.
By thus coating the support with the photosensitive resin composition of the present invention, a photosensitive resin plate material can be obtained.

In order to form a printing plate using the photosensitive resin plate material of the present invention, a negative or positive original drawing film is brought into close contact with the photosensitive layer produced as described above, and usually a wavelength of 300 to 400 mμ is applied. High pressure mercury lamp as the center,
Pattern exposure is performed by irradiating light from ultra-high pressure mercury lamp, metal halide lamp, xenon lamp, carbon arc lamp, chemical lamp, etc. The exposed area is insolubilized by photopolymerization. Then, using neutral water, a developing operation is performed with a spray developing device or a brush developing device, and the unpolymerized portion is developed using neutral water and eluted into water to form a relief on the support. It It is further dried and used as a printing plate for printing. The printing plate of the present invention has a Shore A hardness of 40 to 40 according to ASTM D2240.
No. 75 can be preferably used as a flexographic printing plate.

If necessary, this may be subjected to actinic ray treatment in air or vacuum to further promote photopolymerization of the relief portion, and then used for printing.

The photosensitive resin composition of the present invention has a high degree of image reproducibility and flexibility which is effective as a flexographic printing plate, has good water developability, and satisfies the compatibility with water-based inks. It is a thing.

This is because the photosensitive resin composition itself is made water-developable by containing a hydrophilic polymer and rubber, and since the water-insoluble rubber is contained, the flexibility of the printing plate is improved. Further, the resistance to water-based ink in which a resin is dissolved in a solvent containing water as a main component is remarkably improved.

[0037]

EXAMPLES The present invention will be described in detail below with reference to examples.

The numbers of parts used in the following examples are parts by weight, and the number average molecular weight unless otherwise specified is the value obtained by combining the viscosity measurement method and the GPC method. The relative viscosity [ηr] is measured at 25 ° C. by dissolving the polymer in 98% sulfuric acid at a ratio of 1 g / 100 cc.

An example of synthesizing the hydrophilic polymer used in each example will be described below.

Synthesis Example A-1 <Synthesis of Polyamide Having Ether Bond> Equimolar salt of ε-caprolactam / hexamethylenediamine and adipic acid / α, ω-diaminopropylpolyoxyethylene (number average molecular weight 1000) and adipic acid A copolyamide was obtained from an equimolar salt of (20/20/60 weight ratio).

When the terminal groups of the copolymerized polyamide obtained here were quantified, the primary amino groups were 4.0 × 10 ^-5 mol / g,
The carboxyl group was 2.1 × 10 ⁻⁵ mol / g, and the number average molecular weight determined by the end group determination method was about 33,000.
This polymer had a property of being soluble in water at 25 ° C.

A-2 <Synthesis of Polyamide Having Sulfonic Acid Group in Side Chain> 113 g of ε-caprolactam, 17.6 g of hexamethylenediamine and 66 g of α-aminocaproic acid were charged in an autoclave, and after nitrogen substitution, Temperature of contents 230
The reaction was carried out at 0 ° C for 3 hours. After cooling, 244 g of 3-hydroxy-butanesulfonic acid lactone and 13.8 g of potassium sulphate were added to the reaction mixture, the atmosphere was replaced with nitrogen and the temperature was again 230 ° C.
And reacted for 1 hour to obtain a copolyamide. This polymer had a property of being soluble in water at 25 ° C.

A-3 <Synthesis of polyamide having piperazine skeleton> 50 parts of N, N'-di (γ-aminopropyl) piperazine adipate, 30 parts of ε-caprolactam and 20 parts of water were autoclaved. After charging the inside, purging with nitrogen, hermetically sealing and gradually heating. From the time when the internal pressure reached 10 kg / cm ² , water was distilled off until the pressure could not be maintained, the pressure was returned to normal pressure in about 2 hours, and then the reaction was performed at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255 ° C. The obtained polymer was a transparent pale yellow polyamide having a softening point of 90 to 105 ° C. and [ηr] 2.3. This polymer had a property of being soluble in water at 25 ° C.

A-4 <Synthesis of polyamide having amino group in side chain. > 90 parts of α-dimethylamino-ε-caprolactam, water 1
0 part was placed in an autoclave, replaced with nitrogen, sealed and gradually heated. From the time when the internal pressure reached 3.5 kg / cm ² , water was distilled off until the pressure could not be maintained, the pressure was returned to normal pressure in about 2 hours, and then the reaction was performed at normal pressure for 2 hours. The maximum polymerization reaction temperature was 260 ° C. The obtained polymer was [ηr] 2.5. This polymer is 25
It had a property of dissolving in water at ℃.

Example 1 20 parts of the copolymerized polyamide obtained in Synthesis Example A-1 and a carboxyl group-modified nitrile butadiene rubber (Nipol 10
72 Number average molecular weight 500000 Nippon Zeon Co., Ltd.
80 parts) and a melted mixture were obtained by using an internal mixer operated at 180 ° C.

The morphology of this molten mixture was observed with a scanning electron microscope (JSM-T300 manufactured by JEOL Ltd., measurement condition: backscattered electron composition image). As a result of the observation, it was confirmed that the A-1 polymer had a sea-island dispersed structure in which the carboxylated nitrile butadiene rubber was islands in the sea and the diameter thereof was in the range of 0.5 to 4 microns.

60 parts of this molten mixture was added to ethanol / water =
90 ° C in 160 parts by weight of 60/40 (parts by weight) mixed solvent
It was dissolved by heating.

Then, 2 parts by weight of glycidyl methacrylate was added and reacted at 80 ° C. for 1 hour to react the amino group and carboxyl group at the terminal of the polyamide with the epoxy group of glycidyl methacrylate to introduce a methacryloyl group at the terminal of the polyamide. did. Then, 30 parts by weight of β-hydroxyethyl-β′-acryloyloxyethyl phthalate was added as a photopolymerizable unsaturated compound, 2 parts by weight of dimethylbenzyl ketal as a photopolymerization initiator, and hydroquinone monomethyl ether of 0.2. 1 part by weight and 6 parts by weight of sodium methylenebisnaphthalene sulfonate were added and sufficiently stirred and mixed.

The thus-obtained solution of the photosensitive resin composition was applied onto a polyester substrate having a thickness of 100 μm, which had been coated and cured with a polyester adhesive, to give a photosensitive layer having a thickness of 1700 μm. Thus, casting, coating and leaving at room temperature to obtain a solid photosensitive resin printing plate material having a compression strength of 4 kg / cm ² of the raw plate.

The form of this plate material was observed with a scanning electron microscope (JSM-T300 manufactured by JEOL Ltd., measurement condition: backscattered electron composition image). As a result of the observation, it has a sea-island dispersed structure composed of the sea composed of the A-1 polymer and the photopolymerizable unsaturated compound, and the island of carboxylated nitrile butadiene rubber,
The diameter was confirmed to be in the range of 0.5-4 microns.

On the photosensitive layer of this printing plate material, a gray scale negative film for sensitivity measurement (manufactured by Stouffer, 2
1Steps Sensitivity Guide)
And negative film for image reproducibility evaluation (150 lines 3%,
5%, 10% halftone dots, diameter 200 μm, and 300 μm
Independent exposure point, width of 50 and 70 μm (with fine line) are vacuum-bonded to each other, and 15 units of 20 W chemical lamps are lined up for 15 exposure units.
It was exposed for 10 minutes from a distance of cm.

After completion of the exposure, development was carried out with a brush type washing machine (liquid temperature 35 ° C.) containing neutral water. A relief image having a depth of 750 μm was formed after 5 minutes of development, and this was used as a printing plate. As a result of evaluating this relief image, it was found that the gray scale part remained up to 16 steps, and the image part reproduced almost completely 5% halftone dots, 300 μm independent points, 50 μm fine lines and the like. When post-exposure was carried out with actinic rays, the hardness of the relief was Shore A hardness 60. Using this printing plate, a flexographic printing test was performed on 100,000 sheets using water-based ink,
Good printed matter was obtained.

Comparative Example 1 In Example 1, a photosensitive resin printing plate material was similarly prepared by using 60 parts of A-1 polymer alone without using the melt mixture of A-1 polymer and carboxylated nitrile butadiene rubber "Nipol 1072". Obtained. This printing plate material had a Shore A hardness of 90 and was a hard flexographic printing plate material. Further, when a flexographic printing test was performed on 20000 sheets with this printing plate material, relief printing was found on the printing plate after printing.

Comparative Example 2 All the examples were obtained except that the rubber component of the molten mixture of Example 1 was replaced with liquid polybutadiene rubber (M2000-20 number average molecular weight 2000 manufactured by Nippon Petrochemical Co., Ltd.) to obtain a mixture. A photosensitive resin printing plate material was obtained in the same manner as in Example 1, but the printing plate material after exposure had no morphological retention as a plate
Although it had a hardness of 40 and was extremely soft, it had little elasticity and had tackiness even after exposure, thus causing problems such as staining the negative film.

Example 2 Preparation of a photosensitive resin composition solution and photosensitivity were all carried out in the same manner as in Example 1 except that the A-1 polymer of Example 1 was replaced with the A-2 polymer to obtain a molten mixture. A printing plate having a relief image could be obtained through the production of the resin plate material. The printing plate had a Shore A hardness of 68 after the completion of post-exposure with actinic rays. 100 using water-based ink using this printing plate
A flexographic printing test was performed on 000 sheets, and good printed matter was obtained.

Example 3 Production of a photosensitive resin composition solution and production of a photosensitive resin were all carried out in the same manner as in Example 1 except that the melt mixture was obtained by replacing the A-1 polymer of Example 1 with the A-3 polymer. A printing plate having a relief image could be obtained through the production of the plate material. The hardness of the printing plate was Shore A hardness 62 after the completion of post-exposure of actinic rays. 1000 using water-based ink with this printing plate
A flexographic printing test of 00 sheets was performed, and good printed matter was obtained.

Example 4 Production of a photosensitive resin composition solution and production of a photosensitive resin were conducted in the same manner as in Example 1 except that the A-1 polymer of Example 1 was replaced with the A-4 polymer to obtain a molten mixture. A printing plate having a relief image could be obtained through the production of the plate material. The hardness of the printing plate was 73 Shore A after the completion of post-exposure of actinic rays. 1000 using water-based ink with this printing plate
A flexographic printing test of 00 sheets was performed, and good printed matter was obtained.

Example 5 Example 1 was the same as Example 1 except that the rubber component of the melt mixture of Example 1 was replaced by ethylene propylene rubber (JSR EP33 number average molecular weight 70,000 manufactured by Japan Synthetic Rubber Co., Ltd.) to obtain a melt mixture. Similarly, a printing plate having a relief image could be obtained through the production of a photosensitive resin composition solution and the production of a photosensitive resin plate material. The hardness of the printing plate was Shore A hardness 70 after the completion of post-exposure of actinic rays. Using this printing plate, a flexographic printing test was performed on 100,000 sheets using a water-based ink, and good printed matter was obtained.

Example 6 The rubber component of the molten mixture of Example 1 was styrene-butadiene rubber (Nipol 1507 number average molecular weight 800000).
A relief image can be obtained through the production of a photosensitive resin composition solution and the production of a photosensitive resin plate material in the same manner as in Example 1 except that a molten mixture is obtained instead of Nippon Zeon Co., Ltd.). did it. The printing plate had a Shore A hardness of 63 after the end of exposure to actinic radiation. Using this printing plate, a flexographic printing test was carried out on 150,000 sheets using a water-based ink to obtain a good printed matter.

Example 7 All were the same as in Example 1 except that the rubber component of the melt mixture of Example 1 was replaced by nitrile butadiene rubber (N230S number average molecular weight 60000 manufactured by Nippon Synthetic Rubber Co., Ltd.) to obtain a melt mixture. Thus, a printing plate having a relief image could be obtained through the production of a photosensitive resin composition solution and the production of a photosensitive resin plate material. The printing plate had a Shore A hardness of 65 after the end of post-exposure with actinic rays. Using this printing plate, a flexographic printing test of 120,000 sheets using a water-based ink was carried out to obtain a good printed matter.

Example 8 30 parts of the copolymerized polyamide obtained in Synthesis Example A-1 and carboxylated nitrile butadiene rubber (Nipol 1072)
Number average molecular weight 500000 manufactured by Nippon Zeon Co., Ltd. 70
A molten mixture was obtained using an internal mixer, parts of which were operated at 180 ° C. 40 parts of this molten mixture and synthetic rubber latex (Lacstar DM801 non-volatile content 50%
32 parts by solid content of Dainippon Ink and Chemicals Inc. was dissolved in 100 parts by weight of a mixed solvent of ethanol / water = 90/10 (parts by weight) at 80 ° C. while heating.

Then, 2 parts by weight of glycidyl methacrylate was added and reacted at 70 ° C. for 1 hour to react the epoxy groups of glycidyl methacrylate with the amino groups and carboxyl groups at the ends of the polyamide to introduce methacryloyl groups at the ends of the polyamide. did. Then, 30 parts by weight of β-hydroxyethyl-β′-acryloyloxyethyl phthalate was added as a polymerizable unsaturated compound, and 2 parts by weight of dimethylbenzyl ketal was further added as a photoinitiator.
Thermal polymerization inhibitor hydroquinone monomethyl ether 0.1
Parts by weight and 6 parts by weight of sodium methylenebisnaphthalenesulfonate were added and thoroughly mixed with stirring.

The solution thus obtained is applied to a polyester adhesive in advance and cured to a thickness of 100.
2000 μm thick photosensitive layer on μm polyester substrate
It was cast so as to have a thickness of μm, coated, and allowed to stand at room temperature to obtain a solid photosensitive resin printing plate material.

The obtained plate material was exposed and developed in the same manner as in Example 1 to obtain a relief image. The hardness of the printing plate was Shore A hardness 58 after the completion of post-exposure with actinic rays.
180,000 using water-based ink using this printing plate
A flexographic printing test was performed on one sheet to obtain a good printed matter.

Example 9 30 parts of the copolyamide obtained in Synthesis Example A-1 and carboxylated nitrile butadiene rubber (Nipol 1072)
Number average molecular weight 500000 manufactured by Nippon Zeon Co., Ltd. 70
A molten mixture was obtained using an internal mixer, parts of which were operated at 180 ° C. Furthermore, 40 parts of this molten mixture and synthetic rubber latex (Lack Star D
M801 50% non-volatile content Dainippon Ink and Chemicals, Inc.
32 parts by solid content, 5 parts by weight of sodium methylenebisnaphthalenesulfonate as a plasticizer were kneaded at 160 ° C. for 3 minutes, and then 30 parts by weight of phenoxy polyethylene glycol acrylate was added as a polymerizable unsaturated compound. , And dimethylbenzyl ketal 2 as a photoinitiator
A part by weight was added and the mixture was kneaded at 140 ° C. for 10 minutes. The photosensitive resin composition thus obtained was heated to 130 ° C. with a press machine, and a polyester substrate having a thickness of 100 μm which had been previously coated and cured with a polyester adhesive and polyvinyl alcohol were previously coated. A printing plate material was obtained by pressing the photosensitive resin composition so that the thickness of the photosensitive layer was 1700 µm between the polyester cover films. The obtained plate material was exposed and developed in the same manner as in Example 1 to obtain a printing plate. The hardness of the printing plate was Shore A hardness 58 after the completion of post-exposure with actinic rays. When a flexographic printing test was performed on 130000 sheets using an aqueous ink using this printing plate, no change was observed on the surface of the printing plate,
Good printed matter was obtained.

Comparative Example 3 Instead of the A-1 polymer of Example 1, a maleic acid half-ester modified isoprene polymer LIR-4 manufactured by Kuraray Co., Ltd.
10 (molecular weight 25,000, acid value 21) was used to obtain a molten mixture with rubber. This molten mixture was dissolved and dispersed in the same mixed solvent as in Example 1, and the formulation was added in the same manner as in Example 1 to obtain a solution of the photosensitive resin composition. A photosensitive printing plate material was prepared in the same manner as in Example 1, and further exposed and developed to obtain a printing plate material. The developing speed was slower than in Example 1, and 5% halftone dots could not be reproduced in the obtained image. When flexographic printing was performed, cracks were found on the relief after printing 5000 sheets.

[0067]

The photosensitive resin composition for a printing plate of the present invention comprises
It has a high degree of image reproducibility and flexibility as a flexographic printing plate, has good water developability, and satisfies compatibility with water-based inks. Therefore, it is possible to provide a flexographic printing plate having excellent printing durability in flexographic printing using a water-based ink or other flexographic ink, and a water-developable flexographic plate material having good rubber elasticity.

Claims (13)

[Claims] 1. A photosensitive resin composition for a printing plate comprising the following components A, B, C and D. A: hydrophilic polymer B: rubber having a molecular weight of 40,000 or more C: photopolymerizable unsaturated compound having an ethylenic double bond in the molecule D: photopolymerization initiator 2. A photosensitive resin composition for a printing plate, which comprises the following components A, B, C and D. A: hydrophilic polymer B: solid rubber C: photopolymerizable unsaturated compound having an ethylenic double bond in the molecule D: photopolymerization initiator 3. The hydrophilic polymer of the component A comprises a polyamide having a sulfonic acid group or a sulfonate group in a side chain, a polyamide having an ether bond in the molecule, a polyamide having a piperidine skeleton and a polyamide having an amino group in a side chain. The photosensitive resin composition for a printing plate according to claim 1, which is at least one kind of hydrophilic polyamide selected from the inside. 4. The photosensitive resin composition for a printing plate according to claim 1, wherein the component B rubber is dispersed in the composition. 5. The photosensitive resin composition for a printing plate according to claim 1, wherein the hydrophilic polymer as the component A and the rubber as the component B are melt-mixed. 6. The photosensitive resin composition for a printing plate according to claim 4, wherein the hydrophilic polymer as the component A and the rubber as the component B are melt-mixed in the range of 100 ° C. to 250 ° C. object. 7. The photosensitive resin composition for a printing plate according to claim 1, which contains each component in the following proportions. Total amount of A component and B component 20 to 90% by weight C component 10 to 80% by weight D component 0.01 to 10% by weight 8. The photosensitive resin composition for a printing plate according to claim 1, wherein the hydrophilic polymer as the component A and the rubber as the component B are contained in a weight ratio of 1: 9 to 8: 2. object. 9. The photosensitive resin composition for a printing plate according to claim 1, wherein the rubber as the component B is a diene polymer or an olefin copolymer. 10. A photosensitive resin plate material obtained by coating the photosensitive resin composition for a printing plate according to claim 1 on a support. 11. The photosensitive resin plate material according to claim 10, which is developable with water. 12. The photosensitive resin composition for a printing plate as claimed in claim 1, further comprising a step of melt-mixing the hydrophilic polymer as the component A and the rubber as the component B in the range of 100 to 250 ° C. Manufacturing method. 13. A method of manufacturing a printing plate comprising a step of pattern-exposing the photosensitive resin plate material according to claim 10 and a step of developing with water after the pattern exposure.