JPH0926666A - Water-developable photosensitive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. having rubber elasticity, superior transparency and improved image forming property as a compsn. using (meth)acrylate-base reactive microgel by using a specified photopolymn. initiator in a photosensitive resin compsn. contg. reactive microgel and a thermoplastic polymer. SOLUTION: This photosensitive resin compsn. contains reactive microgel, a compd. having at least one α,β-ethylenically unsatd. double bond in one molecule, a thermoplastic polymer and an arom. ketone type photopolymn. initiator represented by the formula, wherein (n) is 1 or 2, each of A<1> and A<2> is arom. hydrocarbon having a substituent such as alkyl, alkoxy, carboxyl, alkoxycarbonyl or alkylthio or unsubstd. arom. hydrocarbon, A<1> and A<2> may be connected through X or may not be connected, X is S, carbonyl, -(CH2 )m -, etc., and (m) is 0, 1 or 2.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-developable photosensitive resin composition, and more particularly to a photosensitive resin composition for flexographic printing plates having improved image forming properties.

[0002]

2. Description of the Related Art Conventionally, a flexographic printing plate has been manufactured mainly by using a solvent developing photosensitive resin composition. But,
Since these plates are based on a diene rubber such as polybutadiene, it was necessary to use a halogen solvent such as trichloroethane or tetrachloroethylene as a developing solution at the time of development. Due to problems such as obstacles and environmental pollution, there is a problem that it is currently being regulated. Therefore, it has been desired to develop a flexographic plate which can be developed with water or a water-based developer and has flexo ink resistance.

As one of them, a flexographic printing plate has been proposed which uses a composition prepared by adding a reactive microgel to a rubber or a thermoplastic elastomer as a base material, is water-developable, and has good rubber elasticity and rubber hardness. (JP-A-5-4
5874, JP-A-6-51511, etc.)
It was not always satisfactory in terms of transparency and image forming property. Therefore, in JP-A-6-194833, in order to obtain excellent image formability, a conjugated diene hydrocarbon polymer and / or copolymer and a urethane bond are used as a means for improving the transparency of the photosensitive resin composition. A combination of a compound or a reactive microgel obtained from microgel fine particles obtained by emulsion polymerization of a compound having an α, β-ethylenically unsaturated double bond containing a conjugated diene hydrocarbon polymer Is proposed. In addition, JP-A-7
Japanese Patent Publication No. 92672 discloses a photosensitive resin composition having high resolution and improved transparency by combining a reactive microgel with a photopolymerizable monomer having a small difference in refractive index and a rubber or a thermoplastic elastomer. .

In these prior arts, publicly available,
A reactive microgel obtained from microgel fine particles containing a polymer of a (meth) acrylate compound which is easy to synthesize and has good thermal stability as a main component has a refractive index obtained by the method disclosed in JP-A-7-92672. Although the transparency is improved by combining it with a thermoplastic elastomer having a small difference in thickness, the fact that we have grasped is that, for example, the edge of an outline line with a line width of 500μ is missing and the boundary is unknown, and the outline depth is At 50 μm, even if an attempt is made to form a highlight of 5%, 100 L / inch, the surface of the highlight does not solidify, the height is low due to development, and printing is impossible, and even if the exposure amount is increased, the outline depth almost disappears. However, there is a problem that the surface of the highlight does not harden.

[0005]

The object of the present invention is to provide a composition using the above-mentioned (meth) acrylate-based reactive microgel, which has rubber elasticity, excellent transparency, and improved image forming property. An object of the present invention is to provide an excellent water-developable photosensitive resin composition that has never existed before.

[0006]

Means for Solving the Problems The inventors of the present invention have used the above-mentioned (meth) acrylate-based reactive microgel and an ethylene / vinyl acetate copolymer and / or an ethylene / alkyl alkylate copolymer as a thermoplastic polymer. As a result of earnest studies on the composition using, the use of a specific aromatic ketone initiator as the photopolymerization initiator has rubber elasticity, excellent transparency, and dramatically improved image forming property. Then, they found that the object was achieved, and completed the present invention.

That is, in the present invention, by using a specific aromatic ketone compound such as benzophenone as a photopolymerization initiator, the boundary between the photo-cured part and the uncured part becomes clear, and the formation of thin line dots such as highlights and the like. The edges of white lines are clearly formed. The mechanism of this action is not always clear, but using a photocleavable type, which is an ordinary photopolymerization initiator, causes photo-curing by reaction between a reactive microgel and a compound having an ethylenically unsaturated double bond. Although the reaction with the thermoplastic polymer does not proceed sufficiently even if progresses, it is considered that the boundary part near the uncured part (unexposed part) of the photocured part is partially dissolved during development after exposure. .
On the other hand, when a specific photopolymerization initiator such as benzophenone is used, a thermoplastic polymer such as an ethylene / vinyl acetate copolymer may also react with the reactive microgel and the ethylenically unsaturated diamine due to a hydrogen abstraction reaction during exposure. The reaction with the compound having a heavy bond progresses, and it completely cures to the boundary of the uncured part (unexposed part), and there is little or no dissolution of the boundary part during development, so the formation of fine line dots becomes better. Also, it seems that the edges of the outline lines are also formed sharply.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of the present invention comprises a reactive microgel (1), a compound (2) having at least one α, β-ethylenically unsaturated double bond in one molecule, and a thermoplastic resin. A photosensitive resin composition comprising a polymer (3) and an aromatic ketone photopolymerization initiator (4) represented by the formula (I), a method for producing the same, and flexographic printing using the same. Providing the original version.

Used in the photosensitive resin composition of the present invention,
The reactive microgel (1), which is responsible for photosensitivity and water developability, is one in which a photosensitizing group is introduced outside the particles, and preferably has at least one α, β-ethylenically unsaturated double bond in one molecule. Microgel fine particles (A) prepared by compound (a) by emulsion polymerization or suspension polymerization in the presence of a compound (b) containing a tertiary ammonium salt, and an epoxy group that reacts with a tertiary ammonium salt in one molecule. And a compound (B) having at least one α, β-ethylenically unsaturated double bond.

The microgel fine particles (A) of the present invention are synthesized by using a (meth) acrylate compound as a main component, and a compound having an α, β-ethylenically unsaturated double bond used in the synthesis. Examples of the monofunctional monomer used as (a) include (meth) acrylic acid and (meth)
C ₁ -C ₁₈ alkyl esters of acrylic acid: for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl. C of (meth) acrylic acid such as (meth) acrylate, lauryl (meth) acrylate, etc.
Alkenyl esters of ₂ -C _8: for example, allyl (meth)
Acrylate, etc., glycidyl (meth) acrylate,
Hydroxyalkyl esters of (meth) C ₂ -C ₈ acrylic acid: such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) alkenyloxy alkyl esters of C ₃ -C ₁₉ acrylic acid: e.g. Allyloxyethyl (meth) acrylate etc. are mentioned.

Further, in order to satisfy various resistances and characteristics required for the flexographic printing plate, it is desirable to three-dimensionally crosslink the inside (core) of the microgel fine particles (A), and two or more α's for that purpose are desired. , A polyfunctional monomer having a β-ethylenically unsaturated double bond, as an oligomer, a tri (meth) acrylic acid ester of trimethylolpropane, a di (meth) acrylic acid ester of glycols,
Oligomer having at least two polymerizable unsaturated double bonds such as poly (meth) acrylic acid ester of polyol, (meth) acrylate compound such as di (meth) acrylic acid ester of polyester, divinylbenzene, diallyl phthalate, etc. Etc. These α, β-ethylenically unsaturated double bond-containing compounds are appropriately selected according to the desired physical properties, and can be used alone or in combination of two or more. If necessary, it is also possible to use a compound having an α, β-ethylenically unsaturated double bond other than the above.

Compound (b) containing a tertiary ammonium salt
Is effective as an emulsifier, and is usually 3
A compound having a tertiary amino group is neutralized with an acid and tertiary-chlorinated. Such dimethyl lauryl amine as the low molecular weight of the emulsifier, dimethyl myristyl amine, dimethyl palmityl amine, dimethyl stearyl amine, diethyl laurylamine, diethyl myristylamine, diethyl palmitylamine, C ₆ ~ such as diethyl stearylamine C ₂₀ alkyl and alkenyl tertiary amines, 2,2-dimethylaminoethyl (meth)
Acrylate, 2,2-diethylaminoethyl (meth)
There are reaction products of tertiary amines, which are reactive monomers having an amino group such as acrylate, with acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, propionic acid, butyric acid, and (meth) acrylic acid.

As the polymer emulsifier, a reactive monomer having an amino group such as 2,2-dimethylaminoethyl (meth) acrylate or 2,2-diethylaminoethyl (meth) acrylate is copolymerized with another reactive monomer. Let
Examples thereof include those obtained by neutralizing with an acid thereafter. Furthermore, a polymer obtained by neutralizing an amino group-containing polymer such as a natural polymer such as chitosan or a synthetic polymer such as polyethyleneimine with an acid can be used.

The above polymeric emulsifier is used as it is or by reacting a part of the tertiary ammonium salt with a compound containing an epoxy group such as glycidyl (meth) acrylate and an α, β-ethylenically unsaturated double bond. It can be used as a reactive emulsifier by introducing an α, β-ethylenically unsaturated double bond. By using a reactive emulsifier,
When the microgel particles (A) are three-dimensionally crosslinked, the emulsifier itself can be fixed to the microgel particles. By fixing an emulsifier to the microgel fine particles (A), various resistances such as strength, elongation, hardness, water resistance, and abrasion resistance of the flexographic printing plate using the reactive microgel can be improved.

The polymeric emulsifier is used in an amount of 0.1 to 80% by weight, preferably 3 to 50% by weight, based on the compound (a) having an α, β-ethylenically unsaturated double bond. It is also possible to use a nonionic or cationic low molecular surfactant together with the polymeric emulsifier. When a low-molecular-weight surfactant is used in combination, the polymer emulsifier is 0.1 to 50% by weight, preferably 3 to 20% by weight, based on the compound (a) having an α, β-ethylenically unsaturated double bond. %, And the low molecular weight surfactant is used in an amount of 0.1 to 50% by weight, preferably 0.1 to 20% by weight.

The temperature of the emulsion polymerization is 50 to 95 ° C, preferably 65 to 80 ° C. In the emulsion polymerization, the solid content of the compound (a) having an α, β-ethylenically unsaturated double bond and the emulsifier is 10 to 50% by weight, preferably 15 to 30% by weight.
Performed in weight percent. The particle size of the microgel produced by emulsion polymerization in the present invention is 0.02 as measured by the light scattering method.
２０20 μm.

A compound having an epoxy group and at least one α, β-ethylenically unsaturated double bond in one molecule and a tertiary ammonium salt present on the surface of the microgel fine particles (A) thus produced. By reacting with (B), an α, β-ethylenically unsaturated double bond is introduced on the surface of the microgel fine particles. As the compound (B), glycidyl (meth) acrylate, N-glycidyl (meth)
Examples thereof include epoxy compounds having a polymerizable unsaturated double bond such as acrylamide and glycidyl allyl ether. These compounds (B) are appropriately selected according to the desired physical properties and can be used alone or in combination of two or more. The compound (B) can be reacted at a free ratio of 1 to 100 mol% with respect to the tertiary ammonium base on the surface of the microgel particles. The reaction is 30 to 90 by mixing the compound (B) with the emulsion of microgel.
C., preferably 60 to 80.degree. C., and the stirring is completed for about 2 hours.

As the compound (2) having an α, β-ethylenically unsaturated double bond, various known α, β-ethylenically unsaturated monomers and unsaturated prepolymers can be used. Specific examples of the α, β-ethylenically unsaturated monomer include (meth) acrylic acid, C _{1 to} C ₁₈ alkyl esters of (meth) acrylic acid: for example, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, etc., (meth) acrylic acid C ₂ ~
Alkenyl esters of C _8: for example, allyl (meth) acrylate, glycidyl (meth) acrylate, (meth) hydroxyalkyl esters of C ₂ -C ₈ acrylic acid: such as hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, etc.

C ₃ -C ₁₉ alkenyloxyalkyl esters of (meth) acrylic acid: for example, allyloxyethyl (meth) acrylate, acrylamide, methacrylamide and their derivatives: for example, C ₁ -C ₈ alkyl groups and hydroxyalkyl. N-substituted or N, N′-substituted acrylamide or methacrylamide, diacetone acrylamide or methacrylamide, N, N′-alkylenebisacrylamide or methacrylamide, etc.
Allyl compounds: for example, allyl alcohol, allyl isocyanate, etc., maleic acid, fumaric acid and their esters: for example, C ₁ -C ₁₈ alkyl, halogenated alkyl, alkoxyalkyl mono- or diesters, or other vinyl compounds: for example Styrene, vinyltoluene, divinylbenzene, N-vinylcarbazole,
Examples thereof include N-vinylpyrrolidone.

On the other hand, as the ethylenically unsaturated prepolymer, an ethylenically unsaturated compound having a reactive group such as a carboxyl group, a hydroxyl group or an isocyanate group in polyester, polyurethane, polyether, epoxy resin, acrylic resin or the like is used. Then, the one in which an ethylenically unsaturated group is introduced is used. In the photosensitive resin composition of the present invention, the α, β-ethylenically unsaturated compound as the component (2) may be used alone or in combination of two or more kinds.

The thermoplastic polymer (3) of the present invention is preferably one which has a good compatibility with the reactive microgel and provides a photosensitive resin composition having a small difference in refractive index and a good transparency, for example ethylene.・ Vinyl acetate copolymer and ethylene
Acrylic ester copolymers are most preferably used. Further, the ethylene / vinyl acetate copolymer and the ethylene / acrylic acid ester copolymer markedly improve the water developability of the photosensitive resin composition as compared with the conjugated diene hydrocarbon polymer and the like.

The present inventors generally obtain a reactive microgel obtained from a microgel containing a (meth) acrylate compound as a main component, which is easy to obtain and easy to synthesize and has good thermal stability, an ethylene / vinyl acetate copolymer, and Water-developability with rubber elasticity, excellent transparency, and improved image formability by using together with ethylene / alkyl acrylate copolymer and adding aromatic ketone initiator as photopolymerization initiator The present invention has arrived at the present invention by finding an excellent photosensitive resin composition.

The ethylene / vinyl acetate copolymer used in the present invention preferably has a vinyl acetate content of 20% or more in order to secure rubber elasticity for flexographic printing plates. The polymer also preferably has an acrylic acid ester content of 20% or more.

In the photosensitive resin of the present invention, the above (3)
The component copolymers may be used alone or in combination of two or more. The compounding ratio of the reactive microgel (1), the compound (2) having an α, β-ethylenically unsaturated double bond, and the ethylene / vinyl acetate copolymer or the ethylene / alkyl acrylate copolymer (3) is ( 1) 10 to 90 parts by weight, (2) is 10
To 60 parts by weight, (3) is 1 to 50 parts by weight, preferably 10 to 70 parts by weight of (1) and 10 to (2).
50 parts by weight, (3) is 1 to 40 parts by weight. The aromatic ketone photopolymerization initiator (4) used in the present invention is represented by the following formula (I).

[0025]

Embedded image

[N in the formula (I) is 1 or 2. A ¹
And A ² are each an aromatic hydrocarbon or an unsubstituted aromatic hydrocarbon having a substituent such as an alkyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group and an alkylthio group, and they may be the same. However, they may be different from each other. A ¹ and A ² may or may not be connected via X. Wherein X is a sulfur atom, a carbonyl group, - (CH ₂₎ a m- etc., m is 0 or 1 or 2. ]

Examples of the aromatic ketone photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide and 3,3'-dimethyl. Benzophenone derivatives such as 4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2, Thioxanthone derivatives such as 4-diisopropylthioxanthone, 2
-Chloroanthraquinone, anthraquinone derivative such as 2-ethylanthraquinone, dibenzoyl, 9,10-phenanthrenequinone, dibenzosuberone, xanthone,
Examples thereof include dibenzofuran, isophthalophenone, and their derivatives.

In the photosensitive resin composition of the present invention, the photopolymerization initiator as the component (4) may be used alone or in combination of two or more kinds, or may be combined with a photopolymerization initiator other than the component (4). It is possible. The aromatic ketone photopolymerization initiator (4) is used in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the photosensitive resin composition.

As described above, when a direct cleavage type photopolymerization initiator such as an acetophenone type or benzoin type photopolymerization initiator is used, the image forming property is poor at the plate making of the flexographic printing plate, but the hydrogen abstraction type photopolymerization start When the aromatic ketone photopolymerization initiator represented by the formula (I) which is an agent is used, the image forming property is remarkably improved. Further, a known polymerization inhibitor or polymerization retarder can be added to the photosensitive resin composition of the present invention as desired in order to prevent a dark reaction during storage.

In addition to the above-mentioned components, organic or inorganic fillers, dyes, pigments and the like can be added to the photosensitive resin composition of the present invention, if necessary, and the sheet formability of the resulting plate material is improved. An appropriate plasticizer may be added to improve the flexibility of the printing plate. The plasticizer is not particularly limited as long as it is uniformly compatible with the components (1), (2), (3) and (4) and exhibits a plasticizing effect.

The reactive microgel (1) used in the present invention is an aqueous dispersion. For example, the other components constituting the photosensitive resin composition described above are added and sufficiently mixed to uniformly disperse or dissolve. After drying, or to the reactive microgel from which water has been removed in advance, other components constituting the photosensitive resin composition described above are added to the three rolls, a kneader,
The photosensitive resin composition can be obtained by uniformly mixing using an extrusion kneader or the like.

The photosensitive resin plate material of the present invention has a photosensitive resin layer of the above-mentioned photosensitive resin composition and having a thickness of 1.0 to 10.0 mm, and is produced, for example, as described above. The photosensitive layer can be sheet-formed into a support by using an extrusion molding machine, a press machine or the like.

A preferred example of the step of producing a printing plate using the photosensitive resin composition of the present invention will be described. The photosensitive resin composition is formed into a sheet by hot pressing, and a negative film is vacuum-baked on the surface of the sheet. Step of placing them in close contact with each other, irradiating actinic rays for a short time from the opposite side of the negative film,
Process of forming a cured thin layer on one side, process of irradiating with actinic rays through a negative film and curing imagewise, uncured parts are removed by elution with a developer such as a brush type or spray type developing device. A printing plate can be prepared by sequentially performing a process, a drying process using hot air, etc., and a post-exposure process to complete curing.

Examples of the actinic ray source used for exposure include a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp. Examples of the uncured resin developer include water, an aqueous alkaline solution, and an aqueous surfactant solution.

The haze (%) was measured using a haze meter (NDH-1001DP) manufactured by Nippon Denshoku Kogyo. The sample was prepared by contacting the polypropylene film layer and the polypropylene film layer with the composition obtained between polyester films having an adhesive layer of 10μ in which the adhesive layer surface is covered with a polypropylene film having a thickness of 15μ and having a thickness of 125μ. It is sandwiched and pressed with a spacer using a press machine, and the composition layer has a thickness of 1 mm and is 7 cm x 7 cm.
It was obtained as a sheet having a size of. The measured value was measured at 5 points while being protected by films, and the average value was adopted.

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, first, a method for producing the reactive microgel (1) which is one of the main components of the photosensitive resin composition will be described, and then the photosensitive resin composition will be described.

(A) Synthesis of cationic polymer emulsifier 140 parts lauryl methacrylate, 60 parts 2-dimethylaminoethyl methacrylate, 2-propanol 200
80 parts with stirring in a 2 l reactor under nitrogen atmosphere.
Heated to ° C. Azobisisobutyronitrile (hereinafter AI
BN)) and added for 2 hours, and then A
After adding 0.4 parts of IBN, the reaction mixture was added to 80% for 4 hours.
The temperature was kept at 0 ° C to complete the polymerization. After cooling to room temperature, acetic acid 3
A mixture of 8.2 parts and 1000 parts of water was added, and the mixture was heated to remove 2-propanol and water by azeotropic distillation. Then, 9.0 parts of glycidyl methacrylate was added, and the mixture was heated to 70 ° C. in an air atmosphere and held for 2 hours to obtain a cationic polymer emulsifier having pendant methacryl groups.

(B) Synthesis of Reactive Microgel 36 parts of 2-ethylhexyl acrylate, 4 parts of ethylene glycol dimethacrylate, 50 parts of aqueous solution of reactive cationic polymer emulsifier synthesized in (a) (solid content 20)
%), 160 parts of deionized water were heated to 80 ° C. in a 500 ml reaction vessel under nitrogen atmosphere with stirring. 8 parts of a 3% aqueous solution of azobisamidinopropane dihydrochloride (hereinafter referred to as AAPD) was added and kept for 2 hours, and then 2 parts of a 3% aqueous solution of AAPD was added. After the addition was completed, the reaction mixture was heated to 80 ° C.
Polymerization was completed by holding for a period of time to obtain an aqueous microgel dispersion. The measurement result by the light scattering method was about 0.5 μm.
After allowing the microgel aqueous dispersion to stand overnight, 2.7 parts of glycidyl methacrylate was added, and the mixture was heated to 70 ° C. in an air atmosphere.
The reaction was completed by heating to room temperature and holding for 2 hours.

Further, the obtained reactive microgel aqueous dispersion was evaporated to remove fluidity with an evaporator, and then transferred to a vat and further dried in a vacuum dryer to obtain a powder. The reactive microgel obtained here was stirred for 30 minutes at 105 ° C. in a nitrogen atmosphere using a Labo Plastomill manufactured by Toyo Seiki Seisakusho Co., Ltd., and it was not recolored and was uniformly re-emulsified in water.

Example 1 40 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100.degree.
B-11 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 41%) 40 parts, Bremmer PP-800
(Nippon Oil & Fats Polypropylene Glycol 800 Methacrylate) 19 parts, Aronix M-215 (Toagosei Kagaku Kagaku bis (acryloxyethyl) hydroxyethyl isocyanurate) 1 part, benzophenone 2 parts 2,6-
Kneading with 0.1 part of di-t-butyl-p-cresol,
A uniformly transparent composition having a haze of 31% was obtained. Then, the above composition was added to a polyvinyl alcohol layer having a thickness of 5 μ
It is sandwiched between a polyester film of μ and a polyester film of 125 μ having a thickness of 10 μ so as to be in contact with the adhesive layer and the polyvinyl alcohol layer, and pressure-molded with a press using a spacer to obtain a thickness of A 3 mm sheet was obtained.

From the polyester film side having the adhesive layer of the sheet thus obtained, an ultraviolet fluorescent lamp having a central wavelength of 370 nm was used to measure 1000 mj / c.
After performing m ² exposure, the polyester film on the polyvinyl alcohol side of the sheet is stripped off, a negative film consisting of letters and patterns is adhered to the polyvinyl alcohol layer, and an ultraviolet fluorescent lamp having a center wavelength of 370 nm from the negative film side is used. After image exposure at 6000 mj / cm ² , the negative film was removed, and a brush type developing machine (JOW-A ₃ -P) manufactured by JEOL Seiki was used, and rubbing was performed with neutral water at 40 ° C. for 4.8 minutes. The unexposed portion was removed to a depth of 1 mm, dried, and then exposed to 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate.

The obtained printing plate was 5% and 85 l as shown in FIG.
Ine / inch highlights are formed, and further 3
%, A highlight of 85 line / inch was formed. Also, as shown in Fig. 3, the white line with a negative width of 495μ has a width of 55.
A good flexographic printing plate having a size of 5 μ and a depth of 70 μ was obtained.

Comparative Example 1 2 parts of benzophenone of Example 1 was mixed with 2,2-dimethoxy-
The same composition was kneaded by the same method except that 2-phenylacetophenone was changed to 2 parts to obtain a uniformly transparent photosensitive resin composition having a haze of 34%. Next, a photosensitive resin composition sheet was obtained by the same method as in Example 1. Example 1
After performing image exposure in the same manner as in (1), the negative film was removed, and a commercially available brush type developing machine was used to rub for 5.1 minutes with neutral water at 40 ° C to remove the unexposed portion to a depth of 1 mm. After drying, 2000 mj / cm ² of light was used for post-exposure to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate.

The obtained printing plate was 5% and 85 l as shown in FIG.
Even with ine / inch highlights, the surface was not solidified and the height of the highlights was low, making it impossible to print. Further, as shown in FIG. 4, the depth of the white line with a negative width of 495μ was 68μ, but it was white. The width of the punched line was chipped and the width was unknown, and no good flexographic printing plate was obtained.

Example 2 40 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100 ° C. with a kneader to make a SUMITATE R
B-11 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 41%) 40 parts, Bremmer PP-800
(Nippon Oil & Fats Polypropylene Glycol 800 Methacrylate) 19 parts, Aronix M-215 (Toagosei Chemical Co., Ltd. bis (acryloxyethyl) hydroxyethyl isocyanurate) 1 part, thioxanthone 0.5 parts 2,
It was kneaded with 0.1 part of 6-di-t-butyl-p-cresol to obtain a uniformly transparent composition having a haze of 32%.

Next, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was performed in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used to rub with neutral water at 40 ° C. for 5.4 minutes, and the unexposed portion was 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The printing plate obtained has a highlight of 5% and 85 line / inch, and a white line with a negative width of 495μ has a width of 5
A good flexographic printing plate having a size of 65 μ and a depth of 68 μ was obtained.

Example 3 30 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100 ° C. with a kneader to make a SUMITATE R
B-11 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 41%) 40 parts, Bremmer PP-800
(Nippon Yushi Yushi polypropylene glycol 800 methacrylate) 30 parts, benzophenone 2 parts, 2,6-di-t
It was kneaded with 0.1 part of -butyl-p-cresol to obtain a uniform transparent composition having a haze of 45%.

Then, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was carried out in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used to rub with neutral water at 40 ° C. for 5.2 minutes, and the unexposed portion was 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The printing plate obtained has a highlight of 5% and 85 line / inch, and a white line with a negative width of 495μ has a width of 5
A good flexographic printing plate having a size of 46 μ and a depth of 64 μ was obtained.

Example 4 30 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100 ° C. with a kneader to make a SUMITATE R
B-11 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 41%) 40 parts, Bremmer PP-800
(Polypropylene glycol 800 methacrylate manufactured by NOF CORPORATION) 27 parts, 1,6-hexamethylene dimethacrylate 3 parts, benzophenone 2 parts, 2,6-di-t-butyl-p-cresol 0.1 part and kneading, and haze Is 39
% Uniform transparent composition was obtained.

Then, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was performed in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used to rub with neutral water at 40 ° C. for 3.8 minutes, and the unexposed portion was 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The printing plate obtained has a highlight of 5% and 85 line / inch, and a white line with a negative width of 495μ has a width of 5
A good flexographic printing plate having a depth of 30 μ and a depth of 80 μ was obtained.

Example 5 30 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100 ° C. using a kneader to make a SUMITATE R
B-11 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 41%) 40 parts, Aronix M-120
(Toago Gosei Kagaku 2-ethylhexyl carbitol acrylate) 30 parts, benzophenone 2 parts, 2,6-di-
It was kneaded with 0.1 part of t-butyl-p-cresol to obtain a uniform transparent composition having a haze of 25%.

Next, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was performed in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used to rub with neutral water at 40 ° C. for 3.1 minutes, and the unexposed portion was 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The obtained printing plate is formed to a highlight of 5% and 85 line / inch, and a white line having a negative width of 495 μ has a width of 4
A good flexographic printing plate having a depth of 91 μ and a depth of 21 μ was obtained.

Example 6 30 parts of the reactive microgel obtained in the above (b) was used in a nitrogen atmosphere at 100.degree.
A-20 (Sumitomo Chemical's ethylene vinyl acetate resin, vinyl acetate content 25%) 40 parts, Bremmer PP-800
(Polypropylene glycol 800 methacrylate manufactured by NOF CORPORATION) 27 parts, 1,6-hexamethylene dimethacrylate 3 parts, benzophenone 2 parts, 2,6-di-t-butyl-p-cresol 0.1 part and kneading, and haze Is 41
% Uniform transparent composition was obtained.

Then, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was carried out in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used, and the film was rubbed with neutral water at 40 ° C. for 5.5 minutes to give an unexposed area of 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The printing plate obtained has a highlight of 5% and 85 line / inch, and a white line with a negative width of 495μ has a width of 5
A good flexographic printing plate having a size of 28 μ and a depth of 55 μ was obtained.

Example 7 30 parts of the reactive microgel obtained in (b) above was MB-870 using a kneader at 100 ° C. under a nitrogen atmosphere.
(Nippon Unicar made ethylene / ethyl acrylate resin, ethyl acrylate content 41%) 40 parts, Bremmer PP
-800 (Nippon Oil & Fats Polypropylene Glycol 800
Methacrylate) 27 parts, 1,6-hexamethylene dimethacrylate 3 parts, benzophenone 2 parts, 2,6-di-
It was kneaded with 0.1 part of t-butyl-p-cresol to obtain a uniform transparent composition having a haze of 40%.

Then, a photosensitive resin composition sheet was obtained in the same manner as in Example 1. Further, after image exposure was carried out in the same manner as in Example 1, the negative film was removed, and a commercially available brush type developing machine was used to rub with neutral water at 40 ° C. for 4.5 minutes, and the unexposed portion was 1 mm. Was removed to a depth of ² , and after being dried, exposure was performed at 2000 mj / cm ² using the light source to prepare a photosensitive resin relief plate. Further, in order to remove stickiness on the plate surface, irradiation with a germicidal lamp was performed to obtain a flexographic printing plate. The printing plate obtained has a highlight of 5% and 85 line / inch, and a white line with a negative width of 495μ has a width of 5
A good flexographic printing plate having a size of 35 μ and a depth of 70 μ was obtained.

[0057]

As can be seen from the examples and the comparative examples, the present invention uses a specific photopolymerization initiator in the photosensitive resin composition part containing the reactive microgel and the thermoplastic polymer, and thus forms a good relief. In particular, fine line points can be formed and sharp relief edges can be obtained. Furthermore, during photocuring by exposure, the components of the composition react with each other during exposure, so the curing progresses completely and the image forming properties are dramatically improved, and the flexographic printing plate has excellent water developability. Can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing a highlight portion of a printing plate of the present invention obtained in Example 1.

FIG. 2 is a diagram showing a highlight portion of a printing plate obtained in Comparative Example 1.

FIG. 3 is a view showing an outline line portion of the printing plate of the present invention obtained in Example 1.

FIG. 4 is a view showing a white line portion of a printing plate obtained in Comparative Example 1.

Claims (7)

[Claims] 1. A reactive microgel (1), a compound (2) having at least one α, β-ethylenically unsaturated double bond in one molecule, a thermoplastic polymer (3), and a light source. In the photosensitive composition containing the polymerization initiator (4),
A photosensitive resin composition, wherein the photopolymerization initiator is an aromatic ketone compound. 2. The photosensitive composition according to claim 1, wherein the aromatic ketone compound of the photopolymerization initiator (4) is benzophenone. 3. The reactive microgel (1) comprises a compound (a) having at least one α, β-ethylenically unsaturated double bond in one molecule, and a compound (b) containing a tertiary ammonium salt. Microgel fine particles (A) synthesized by emulsion polymerization or suspension polymerization below, and having an epoxy group and at least one α, β-ethylenically unsaturated double bond which react with a tertiary ammonium salt in one molecule It is a reactive microgel obtained by making it react with a compound (B), The photosensitive resin composition of Claim 1 characterized by the above-mentioned. 4. A compound (a) having at least one α, β-ethylenically unsaturated double bond in one molecule is a (meth) acrylate compound or a mixture containing a (meth) acrylate compound. The photosensitive resin composition according to claim 3. 5. The photosensitive resin composition according to claim 1, wherein the thermoplastic polymer (3) is an ethylene / vinyl acetate copolymer and / or an ethylene / alkyl acrylate copolymer. 6. After drying an aqueous dispersion of the reactive microgel (1), the compound (2) having at least one α, β-ethylenically unsaturated double bond in one molecule, and a thermoplastic polymer. The method for producing a photosensitive resin composition according to claim 1, wherein the polymer (3) and a photopolymerization initiator (4) made of an aromatic ketone compound are mixed. 7. A flexographic printing original plate comprising a support and a photosensitive layer comprising the photosensitive resin composition according to claim 1.