JPH0545874A - Photosensitive resin composition, its production, and flexographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a photosensitive resin compsn. which is a water-developable photosetting resin compsn., to obtain a flexographic printing plate using a photosensitive resin compsn. containing a reactive microgel, and to manufacture a film or sheet for flexographic printing excellent in water resistance, IPA resistance and rubber elasticity. CONSTITUTION:This compsn. contains a reactive microgel (1) and rubber or thermoplastic elastomer (2). The microgel (1) is obtd. by the reaction of microgel fine particles (A) and a compd. (B). The microgel fine particles (A) are synthesized by emulsion polymn. of a compd. having carbon-carbon double bonds with a compd. containing quaternary ammonium salt, and if required, with using a low mol.wt. surfactant. The compd. (B) has at least one epoxy group which reacts with a quaternary ammonium salt and other reactive functional groups in one molecule.

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 which is a water-developable photo-curable resin composition, and more specifically, it has rubber elasticity and has carbon-carbon double carbon on the surface of gel particles. The present invention relates to a flexographic plate material obtained by using a photosensitive resin composition containing a reactive microgel having a bond.

[0002]

2. Description of the Related Art With the recent modernization of packaging, flexographic printing has come into the limelight. However, in the conventional flexo plate manufacturing methods,
(A) Creation of metal plate, (b) mold making, (c) vulcanization of raw rubber requires at least three steps, which requires a skilled technique and a long time, so the cost is considerably high. I could not avoid it. As a result, solvent-developable photosensitive resin plates have appeared, and flexographic plates can be easily made. However, since these plates use a diene rubber such as polybutadiene as a base material, a halogen-based solvent such as trichlene and perkrene must be used as a developing solution when developing. However, recently, halogen-based solvents are being regulated due to environmental problems and toxicity of halogen-based solvents to the human body. Therefore, the advent of flexographic printing plates that can be developed with water that is non-toxic to the human body has been long awaited. Since many inks used for flexographic printing are water-based, the plate is required to have water resistance. However, with the conventional techniques, a water-developable and water-resistant plate cannot be obtained, and there has been a demand for the development of a new water-developable, water-resistant, IPA-resistant and elastic material. Therefore, the present inventors have invented a novel method for synthesizing a reactive microgel (Japanese Patent Application No. 1-328).
665, Japanese Patent Application No. 2-3111091), and application to a flexographic plate was examined, but it was not always possible to obtain a satisfactory rubber elasticity.

[0003]

Therefore, as a result of intensive studies to develop a photosensitive resin composition capable of being developed in water and having physical properties required for a flexographic plate, the present inventor found that a compound having a urethane bond, etc. Water resistance when rubber is added as a second component to the reactive microgel in the core,
The present invention was completed by producing a film or sheet for flexographic printing plates, which is excellent in IPA resistance and rich in rubber elasticity.

[0004]

According to the present invention, a compound having a carbon-carbon double bond is synthesized by emulsion polymerization using a quaternary ammonium salt-containing compound and, if necessary, a low molecular weight surfactant. A reactive microgel (1) which is prepared by reacting the gel particles (A) with a compound (B) having an epoxy group and at least one other reactive functional group which react with a quaternary ammonium salt in one molecule. ) And a rubber or a thermoplastic elastomer (2), and a flexographic plate material using the same.

The microgel fine particles (A), which is the main component of the photosensitive resin composition of the present invention, is characterized by emulsion-polymerizing a compound containing polyurethane having a carbon-carbon double bond. The polyurethane having a carbon-carbon double bond is a diol compound, a diisocyanate compound,
It can be produced from a compound having a hydroxyl group and a carbon-carbon double bond. Examples of the diol compound used here include various lactones, for example, β-propiolactone and its substitution product, δ
-Valerolactone and its substituted compounds, ε-caprolactone and the like 4-membered ring, 6-membered ring, 7-membered ring or more lactone ring-opening polymerized in the presence of ethylene glycol or the like in the presence or absence of a catalyst, or glycol Those condensed with a dibasic acid or the like under conditions of excess components such as polyethylene adipate, polypropylene adipate, polyethylene succinate, polyhexamethylene adipate having a hydroxyl group at the terminal, polyethylene glycol, polypropylene glycol, polyepichlorohydrin, etc. Can be mentioned. Examples of the diisocyanate compound include toluylene diisocyanate, diphenylmethane-4,4 diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate. Examples of the compound having a hydroxyl group and a carbon-carbon double bond include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and allyl alcohol.

Polyurethanes having carbon-carbon double bonds synthesized using the above compounds are used alone or in admixture with various monomers for microgel synthesis. Examples of the various monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth ) acrylate, octyl (meth) C ₁ -C ₁₈ alkyl esters of (meth) acrylic acid and lauryl acrylate: glycidyl (meth) acrylate: allyl (meth)
C ₂ -C ₂₀ alkenyl ester of (meth) acrylic acid such as acrylate: hydroxylethyl (meth) acrylate, hydroxylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylic such as hydroxypropyl (meth) acrylate Acid C
₂ -C ₂₀ hydroxyalkyl ester and allyl oxyl ethyl (meth) acrylate (meth) C ₃ -C ₁₉ alkenyloxy Le alkyl esters of acrylic acid:
(Meth) acrylic acid, trimethylolpropane tri (meth) acrylic acid ester, di (meth) acrylic acid ester of glycols, di (meth) acrylic acid ester of polyols, di (meth) acrylic acid ester of polyurethanes, polyester Di (meth) acrylic acid ester,
Examples thereof include butadiene, isoprene, chloroprene, and divinylbenzene. These monomers and polyurethane having a carbon-carbon double bond can be freely mixed in a weight ratio of 0 to 200.

As the quaternary ammonium salt-containing compound for emulsifying these urethane-containing compounds,
It is effective as an emulsifier, and is usually a compound having a tertiary amino group neutralized with an acid to be quaternized. Among such emulsifiers, low molecular weight emulsifiers include dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, diethyllaurylamine, diethylmyristylamine, diethylpalmitylamine, diethylstearylamine and the like C ₆ To C ₂₀ alkyl and alkenyl tertiary amines, 2,2-dimethylaminoethyl (meth) acrylate, 2,2-diethylaminoethyl (meth) acrylate, etc., a reactive monomer tertiary amine hydrochloric acid having an amino group,
There are reaction products with acids such as nitric acid, sulfuric acid, acetic acid, propionic acid, butyric acid, and (meth) acrylic acid, and 2,2-dimethylaminoethyl (meth) acrylate, 2,2 as a polymeric emulsifier.
Reactive monomers having amino groups such as 2-diethylaminoethyl (meth) acrylate and other reactive monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic C ₁ of (meth) acrylic acid such as isopropyl acid acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, and lauryl (meth) acrylate.
-C ₁₈ alkyl esters: glycidyl (meth) acrylate: allyl (meth) acrylate of (meth) C ₂ -C ₈ alkenyl esters of acrylic acid: hydroxyethyl (meth) acrylate, hydroxyl ethyl (meth)
Acrylate, hydroxypropyl (meth) acrylate, C ₂ -C ₈ hydroxyalkyl esters of (meth) acrylic acid such as hydroxyethyl (meth) acrylate: C ₃ ~ of (meth) acrylic acid and allyl oxyl ethyl (meth) acrylate C ₁₉ alkenyloxyl alkyl ester: C ₁₉ alkenyloxyl alkyl ester: those obtained by copolymerizing one or more vinyl monomers selected from (meth) acrylic acid and the like and then neutralizing with an acid. Further, natural polymers such as chitosan and synthetic polymers such as polyethyleneimine, which are neutralized with an acid, may be used. These polymeric emulsifiers are used as they are or by reacting a part of the quaternary ammonium salt with a compound containing an epoxy group such as glycidyl (meth) acrylate and a quaternary ammonium salt to introduce a carbon-carbon double bond and thereby to make it reactive. It can also be used as an emulsifier.

The above polymeric emulsifier can control the degree of water solubility, and is therefore a preferred emulsifier in applications requiring water resistance. These emulsifiers are 0.1 to monomer.
-80% by weight, preferably 3-50% by weight, and the temperature of emulsion polymerization is 50-95 ° C, preferably 65-80 ° C. Emulsion polymerization has a solid content of 10 to 50, which is the sum of monomer and emulsifier.
Weight% is preferably 15 to 30% by weight. In the present invention,
The particle size of microgels produced by emulsion polymerization is usually
It is 10 to 500 nm as measured by the light scattering method. The quaternary ammonium salt present on the surface of the microgel fine particles (A) thus produced is reacted with the compound (B) having an epoxy group and at least one carbon-carbon double bond in one molecule, A carbon-carbon double bond is introduced on the surface of microgel particles.

Examples of the compound (B) include glycidyl (meth) acrylate, N-glycidyl (meth) acrylamide, glycidyl allyl ether, epoxy compounds having an unsaturated double bond such as 1,2-epoxy-5-hexene, and glycidyl. Examples thereof include cinnamate. These compounds (B) are appropriately selected according to the desired physical properties and may be used alone or in combination of two or more. It is possible to react the quaternary ammonium salt on the surface of the microgel particles in a free ratio of 1 to 100 mol%. This reaction is completed by mixing the epoxy compound in the microgel emulsion and stirring at a temperature of 30 ° C to 90 ° C, preferably 60 ° C to 80 ° C for 2 hours or more. As described above, in the present invention, there is an advantage that the reaction can be performed even in the aqueous dispersion.

Rubber or a thermoplastic elastomer is added as a second essential component to the reactive microgel produced as described above, and additives such as a photopolymerization initiator and other resins are added if necessary. After that, the desired plate is obtained by crosslinking and curing with radiation such as ultraviolet rays and electron beams, and developing with water. Conventionally, a thick resin plate for flexographic plates has been mainly produced by a casting method. (A) Casting → drying → casting is repeated to obtain a plate having a predetermined film thickness. (A) The thick film product is gradually dried around room temperature to obtain a plate having a predetermined film thickness. Methods such as (a) and (a) are conceivable, but in any case, it is not only a very time-consuming and labor-intensive method, but also the problem that the second component and initiator used are limited to aqueous systems. was there. As a result of diligent research to solve this problem, a dry product of a photosensitive resin composition containing a reactive microgel (1) and a second component (2) not limited to an aqueous system is pressure-molded to rapidly and It became possible to easily form a film having a predetermined thickness, and succeeded in dramatically improving the physical properties as a flexographic plate. The method for drying the photosensitive resin composition containing the reactive microgel prior to pressure molding is not particularly limited, such as vacuum drying, freeze drying and spray drying. Naturally, the thin film and thick film formed by the conventional casting method are also applicable.

The rubber or thermoplastic elastomer (2) added for the purpose of supplementing rubber elasticity is appropriately selected from the group consisting of diene type, styrene type, olefin type, urethane type, vinyl type, polyamide type, fluorine type, polyester type and the like. More than one seed is used. As the rubber or thermoplastic elastomer, both synthetic and natural products (rubber) can be used, and raw rubber or latex can also be used. As an example of rubber, SBR (styrene-butadiene copolymer), B
R (butadiene polymer), IR (isoprene polymer),
NBR (Acrylonitrile butadiene copolymer), CR
(Chloroprene polymer), IIR (isobutylene diene copolymer), EPM (ethylene propylene copolymer),
The raw rubber or latex such as AU (polyester isocyanate condensate), EU (polyether isocyanate condensate), ACM (acrylic acid ester polymer) is freely selected.

As a method of adding these rubbers or the thermoplastic elastomer (2), the following methods can be considered. (I) Addition / Mixing → Drying The second component is added to the reactive microgel aqueous dispersion, and then dried. When the second component is uniformly dispersed or dissolved in the reactive microgel aqueous dispersion, the dried product can be immediately pressure-molded. On the other hand, if it is not so uniform, it goes without saying that it is necessary to sufficiently disperse it after drying before pressure molding. This method is mainly used for the latex of the rubber or the thermoplastic elastomer (2), and is particularly applied to the cationic or nonionic latex. When the anionic latex is water-based and mixes with the reactive microgel (1) water dispersion, it agglomerates, and the water developability when formed into a plate is deteriorated. In this case, the following (II) is shown. It is advisable to mix the dried products together. In addition, although the patent for mixing the latex in the reactive microgel aqueous dispersion was previously filed, in the case of this earlier application, the film forming method is mainly the casting method, and the present application is to dry and mold. Is very different. (II) Drying → Mixing After drying the reactive microgel aqueous dispersion, (2) was added and mixed (dispersed, kneaded) with a two-roll, three-roll, kneader, etc. to obtain a uniform dispersion, and then added. Press molding.
If (2) is aqueous, it must be dried in advance. The drying method at this time is not particularly limited as described in the section of drying the reactive microgel.

If necessary, an initiator, a sensitizer, a filler, and other additives can be added to these photosensitive resin compositions. As a method of adding these initiators, sensitizers and the like, either (I) addition / mixing → drying or (II) drying → addition / mixing may be performed as in the case of adding (2) above. The photosensitive resin composition containing the reactive microgel and (2) produced as described above is used to prepare a film or sheet for a plate by using an extruder, an extrusion molding machine, a press machine or the like. .. Initially, I thought it would be impossible to obtain a continuous film by subsequent processing if the microgel that had been made into fine particles was once dried to form a discontinuous film.
It was possible to obtain a continuous film which is sufficiently uniform by itself and which is stronger by mixing the second component. This is crosslinked and cured by radiation such as ultraviolet rays and electron beams to form an image and obtain a plate. This cured film was significantly improved in breaking strength, breaking elongation, and rubber hardness as compared with those prepared by a conventional reactive microgel by a casting method and a pressure molding method. resolution,
The various characteristics required for flexographic printing plates such as water resistance, alkali resistance, and IPA resistance were comparable to those of the reactive microgel alone.

Crosslinking by radiation occurs even without a photopolymerization initiator, but in the case of ultraviolet irradiation, the crosslinking efficiency is enhanced by adding an appropriate photopolymerization initiator. As the photopolymerization initiator, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) 2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [Four-
(Methylthio) phenyl] 2-morpholinopropanone-1 and the like. The amount of these photopolymerization initiators added depends on the resin.
It is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight.

Other water-based resins include polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose,
Examples thereof include hydroxyethyl cellulose, casein, gelatin, starch, polyvinylpyrrolidone, poly (meth) acrylamide, chitosan, and quaternary ammonium salt-containing polymers. Examples of hydrophilic monomers
N, N-methylenebis (meth) acrylamide, 1,2-di (meth) acrylamide ethylene glycol, N, N-oxymethylenebisacrylamide, (meth) acrylamide,
Examples include vinylpyrrolidone, 2-hydroxyethyl (meth) acrylate, polyoxyethylene (meth) acrylate, polyoxyethylene (meth) acrylate and the like. Further, in order to impart various functions to the resin of the present invention, a colorant, an extender pigment, a lubricant, a plasticizer, a stabilizer, a flame retardant, a defoaming agent, an antioxidant, a bactericide, a conductive material, and
It is also possible to contain additives such as magnetic materials.

[0016]

EXAMPLES The following examples show a method for producing a reactive microgel, which is one component in a resin composition, and changes in water resistance and solvent resistance of the resin due to addition of the reactive microgel. In the example,
Parts and% indicate parts by weight and% by weight. a. Preparation of Cationic Polymer Emulsifier 140 parts of lauryl methacrylate, 60 parts of 2-dimethylaminoethyl methacrylate and 200 parts of 2-propanol were heated to 80 ° C. in a 2 liter reaction vessel with stirring in a nitrogen atmosphere. Azobisisobutyronitrile (hereinafter referred to as AIBN)
1.6 parts was added and held for 2 hours, then 0.4 parts AIBN was added,
Then, the reaction mixture was kept at 80 ° C. for 4 hours to complete the polymerization. After cooling to room temperature, a mixture of 38.2 parts of acetic acid and 1000 parts of water was added and 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 Urethane Methacrylate 1 100g of polyester diol consisting of butanediol-adipic acid having a molecular weight of about 1000, 75g of diphenylmethane diisocyanate and 0.1g of dibutyltin laurate are mixed to obtain 50
After reacting for 30 minutes at 90 ℃ and for 2 hours at 90 ℃, cool to 70 ℃ and
-Additional 26 g of hydroxyethylmethacrylate
The reaction was continued for a period of time to obtain urethane dimethacrylate. c. Synthesis of Urethane Methacrylate 2 100 g polyester diol consisting of butanediol-adipic acid with a molecular weight of about 1000 and toluylene diisocyanate
Mix 52.2g and 0.1g dibutyltin laurate and mix at 50 ℃ for 3
After reacting for 0 minutes at 90 ° C. for 2 hours and then cooled to 70 ° C., 26 g of 2-hydroxyethyl methacrylate was added and the reaction was continued for another 3 hours to obtain urethane dimethacrylate.

(Reactive Microgel Synthesis Example 1) b. 40 parts of urethane dimethacrylate synthesized in a. 100 parts aqueous solution of reactive cationic polymer emulsifier synthesized in (solid content 2
0%), 160 parts of deionized water were heated to 80 ° C. in a nitrogen atmosphere under stirring in a 500 ml reaction vessel. 8 parts of a 3% aqueous solution of azobisamidinopropane dihydrochloride (hereinafter referred to as AAPD) was added and the mixture was kept for 2 hours. Then, 2 parts of a 3% AAPD aqueous solution was added. After the addition was completed, the reaction mixture was kept at 80 ° C for 4 hours to complete the polymerization. The measurement result of the particle diameter by the light scattering method was about 200 nm. After leaving this microgel aqueous dispersion overnight, add 2.7 parts of glycidyl methacrylate and add 70 parts in an air atmosphere.
The reaction was completed by heating to ℃ and holding for 2 hours. (Reactive Microgel Synthesis Example 2) b. 30 parts of urethane dimethacrylate synthesized in Step 3, 10 parts of polypropylene glycol monomethacrylate, a. 100 parts of the reactive cationic polymer emulsifier aqueous solution (solid content 20%) and 160 parts of deionized water synthesized in step 500 were stirred in a 500 ml reaction vessel under a nitrogen atmosphere.
Heated to ° C. 8 parts of a 3% aqueous solution of azobisamidinopropane dihydrochloride (hereinafter referred to as AAPD) was added and the mixture was kept for 2 hours.
Then, 2 parts of a 3% AAPD aqueous solution was added. After the addition was completed, the reaction mixture was kept at 80 ° C for 4 hours to complete the polymerization. The measurement result of the particle size by the light scattering method was about 50 nm. After leaving this microgel aqueous dispersion overnight, 2.7 parts of glycidyl methacrylate was added and the reaction was completed by heating to 70 ° C. in an air atmosphere and holding for 2 hours.

(Drying Example 1) 200 parts of each of the reactive microgels obtained in Synthesis Examples 1 and 2 and 200 parts of an aqueous dispersion (solid content: 25%) and 2.5 parts of Darocur 2959 (trade name, manufactured by Merck). In addition, water was distilled off with an evaporator until the fluidity disappeared, and then transferred to a vat and further dried in a vacuum dryer to obtain a powder. During this time, the time required to obtain powder from the dispersion is about 3
It was time. (Drying Example 2) 200 parts of each of the reactive microgels obtained in Synthesis Examples 1 and 2 and 200 parts of an aqueous dispersion (solid content: 25%) and water were distilled off with an evaporator until the fluidity disappeared, and then The powder was transferred to a vat and further dried in a vacuum dryer to obtain a powder. During this time, the time required to obtain a powder from the dispersion was about 3 hours.

(Mixing Examples 1 and 2) 3 parts of rubber JSRBR02L (manufactured by Japan Synthetic Rubber Co., Ltd.) and 0.5 part of Darocur 2959 (manufactured by Merck, Inc.) were respectively added to 7 parts of the two kinds of powders obtained in Drying Example 2. In addition, it was dispersed with a three-roll mill to make it uniform. (Mixing Examples 3 and 4) 7 parts of the two kinds of powders obtained in Drying Example 2, 3 parts of rubber JSRN211SL (manufactured by Japan Synthetic Rubber Co., Ltd.) as mixing example 3, and Lavalon MJ4 as mixing example 4
3 parts of 300 (styrene-butadiene-styrene-based thermoplastic elastomer manufactured by Mitsubishi Petrochemical Co., Ltd.) and 0.5 parts of Darocur 2959 (trade name, manufactured by Merck & Co., Inc.) were added and dispersed by a three-roll mill to make uniform. (Pressure molding method) About 10 parts of each powder obtained in Drying Example 1 or each photosensitive resin composition obtained in Mixing Examples 1 to 4 was pressed by a press machine to form a uniform film of about 3 mm. .. Press conditions
50 ° C, 100 kg / cm ² , 15 minutes.

(Evaluation of physical properties) The film prepared as described above was irradiated with ultraviolet rays of 4000 mJ / cm ² to obtain a cured film. With respect to this cured film, the breaking strength, breaking elongation, rubber hardness, water resistance, alkali resistance, and IPA resistance were measured at room temperature (25 ° C). Water resistance, alkali resistance, and IPA resistance are deionized water, sodium carbonate aqueous solution (pH = 9), isopropyl alcohol (IP
It was soaked in A) for 24 hours and evaluated by measuring the swelling rate. Breaking strength, breaking elongation: Measured by a tensile tester Sample size: 10 * 20 * 3 (mm) Test condition: Pulling speed 50mm / min Rubber hardness: According to JIS-K6301. Swelling rate = ((weight after soaking for 24 hours / weight before soaking) -1) * 10
Further, the thinnest line width obtained by overlaying each film with a mask film having a pattern of various line widths, irradiating with the above ultraviolet rays, and developing with water was taken as the resolution. The results are shown in Table 1.

[0021]

[Table 1]

By thus adding the component (2) to the reactive microgel, break strength, break elongation, rubber hardness, etc. are dramatically improved, and an excellent flexographic plate capable of water development can be manufactured. It was

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Claims (5)

[Claims] 1. A microgel fine particle (A) obtained by synthesizing a compound having a carbon-carbon double bond by a quaternary ammonium salt-containing compound and, if necessary, an emulsion polymerization using a low molecular weight surfactant, and 1. A reactive microgel (1) obtained by reacting a compound (B) having an epoxy group which reacts with a quaternary ammonium salt and at least one other reactive functional group in the molecule, and a rubber or a thermoplastic elastomer ( A photosensitive resin composition comprising 2). 2. The rubber or thermoplastic elastomer (2) is one or more selected from dienes, styrenes, olefins, urethanes, vinyls, polyamides, fluorines and polyesters. The photosensitive resin composition according to claim 1. 3. The rubber (2) comprises SBR (styrene-butadiene copolymer), BR (butadiene polymer), IR (isoprene polymer), NBR (acrylonitrile-butadiene copolymer), CR (chloroprene polymer), IIR
One selected from (isobutylene diene copolymer), EPM (ethylene propylene copolymer), AU (polyester isocyanate condensate), EU (polyether isocyanate condensate) or ACM (acrylic ester polymer) or It is 2 or more types, The photosensitive resin composition of Claim 1 characterized by the above-mentioned. 4. A method for producing a photosensitive resin composition, which comprises drying the reactive microgel aqueous dispersion (1) according to claim 1 and mixing the rubber or the thermoplastic elastomer (2). 5. A flexographic printing plate comprising the photosensitive resin composition according to claim 1.