JPH0572734A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a photosensitive resin compsn. which can be developed with a water-base developer after exposure and has resistance against an alcohol-base ink so that the photosensitive resin plate obtd. from this resin compd. has a rubber elasticity and excellent characteristics as a flexographic printing plate and can be used for a photoresist or screen for screen printing. CONSTITUTION:This resin compsn. consists of the following component. (1) 10-90wt.% of elastomers containing carboxyl groups obtd. by the reaction of hydrocarbon polymers having hydroxyl groups and copolymers having carboxyl groups (including acid anhydride groups) in a proportion that the eqiv. of the carboxyl group exceeds the eqiv. of hydroxyl groups. (2) 1-40wt.% of unsatd. compd. having ethylene type molecular end. (3) 0.01-10wt.% of photopolymn. initiator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition which has rubber elasticity and can be developed with an aqueous washout solution and which is suitable for preparing a flexographic printing plate.

[0002]

2. Description of the Related Art Conventionally, as a plate material for flexographic printing,
There is known a photosensitive resin plate containing styrene-butadiene rubber or acrylonitrile-butadiene rubber as a main component and a photopolymerizable compound having an ethylenically unsaturated group added thereto. However, since it is necessary to use an organic solvent, particularly a halogenated hydrocarbon such as 1,1,1-trichloroethane, as a developing solution, there are problems such as toxicity to workers and environmental pollution such as air pollution. For such problems, attempts have been made to produce a water-developable flexographic printing plate.

For example, a compound obtained by copolymerizing a conjugated diene hydrocarbon and an ethylenically unsaturated carboxylic acid as essential components with a monoolefin unsaturated compound, a photopolymerizable unsaturated monomer, and photopolymerization initiation. Of using a photosensitive resin composition containing an agent (JP-A-52-134655), a high molecular weight and low molecular weight butadiene / acrylonitrile copolymer mixture having a carboxyl group, a non-gaseous ethylenically unsaturated compound, an organic compound Photosensitive elastic composition containing an irradiation-sensitive free radical producing system (JP-A-54-
110287). These compositions, by introducing a carboxyl group into the skeleton of the elastic body,
It is characterized in that it can be developed with alkaline water or an alkaline water / organic solvent system and has rubber elasticity.

[0004]

However, in these photosensitive compositions, in the former case, carboxyl groups are randomly introduced into the skeletal polymer, so that the polarity is too strong and there is no resistance to alcohol-based inks. Cannot be used for normal flexographic printing. On the other hand, the latter has a low content of carboxyl groups and cannot obtain sufficient alkali developability.

[0005]

Under the circumstances, the present inventors have studied various rubber elastic polymers, and as a result, a photosensitive resin composition having a carboxylic acid-containing half ester as a skeleton was used for flexographic printing plates. As a result, the present invention has been completed, and the present invention has been completed. That is, the present invention is obtained by reacting (a) a hydrocarbon polymer having a hydroxyl group and a copolymer having a carboxyl group (including an acid anhydride group) at a ratio in which the carboxyl group equivalent exceeds the hydroxyl group equivalent. A carboxyl group-containing elastomer; 10 to 90% by weight; (B) a terminal ethylenically unsaturated compound; 1 to 40% by weight; (C) a photopolymerization initiator; 0.01 to 10% by weight. The present invention provides a photosensitive resin composition which can be developed with an aqueous developer after exposure and which is resistant to alcohol-based ink and is particularly useful for flexographic printing plates.

The hydrocarbon polymer having a hydroxyl group used in the (a) carboxyl group-containing elastomer of the present invention is a homopolymer or copolymer of butadiene, isoprene or chloroprene, or butadiene, isoprene, chloroprene and styrene. , Isobutylene, propylene, ethylene, acrylonitrile, acrylic acid ester, a copolymer with neoprene, or a polymer obtained by introducing a hydroxyl group into a partially hydrogenated corresponding polymer.
After these copolymerization reactions, for example, anionic polymerization reaction, ethylene oxide is added to open the ethylene oxide with a carbanion at the terminal, or water is added to introduce a hydroxyl group at the terminal. The hydrocarbon polymer having a hydroxyl group used in the present invention generally has a hydroxyl group equivalent of 500 to 50,000 and a number average molecular weight of 50.
Those of 0 or more and 100,000 or less are used. If the molecular weight is too low, sufficient rubber elasticity cannot be obtained, and if the molecular weight is too high, sufficient polarity cannot be obtained as the component (a).

Copolymers having a carboxyl group include polymerizable ethylenically unsaturated compounds such as ethylene, methylstyrene, isobutene and acrylic acid esters, and unsaturated dicarboxylic acids such as maleic acid, maleic anhydride and fumaric acid. A polymer obtained by subjecting and to a copolymerization reaction is used. Specific examples thereof include a styrene / maleic anhydride copolymer, an isobutene / maleic anhydride copolymer, a methyl acrylate / maleic anhydride copolymer and the like.
As the copolymer having a carboxyl group used in the present invention, those having an acid value of 50 to 750 and a number average molecular weight of 1,000 or more and 200,000 or less are generally used.

The reaction between the hydroxyl group-containing hydrocarbon polymer and the carboxyl group-containing copolymer is carried out in such a ratio that the carboxyl group equivalent of the carboxyl group-containing copolymer exceeds the hydroxyl group equivalent of the hydroxyl group-containing hydrocarbon polymer. It is preferable to react at a ratio of carboxyl group / hydroxyl group> 1.3 in an equivalent ratio to esterify. When the carboxyl group is an anhydride group, it easily reacts with the hydroxyl group of the hydrocarbon polymer having a hydroxyl group to form a half ester, and an elastomer having an ester and a free carboxylic acid group can be obtained. At this time, by adding a low molecular weight alcohol such as methyl alcohol or ethyl alcohol or a glycol such as ethylene glycol or diethylene glycol, it is possible to react with the dicarboxylic acid anhydride and increase the amount of free carboxylic acid. The amount of addition of these alcohols is such that the sum of the equivalents of the hydroxyl group-containing hydrocarbon polymer and the alcohols is not more than 1/2 of the carboxyl group equivalent of the dicarboxylic acid anhydride.

The esterification is carried out by mixing a hydrocarbon polymer having a hydroxyl group and a copolymer having a carboxyl group with
It is carried out by heating to 00 to 200 ° C. and stirring for about 0.5 to 2 hours. The reaction may be carried out using a solvent such as tetrahydrofuran, dioxane, methyl ethyl ketone, toluene and the like. Further, a catalyst such as a tertiary amine or an amine salt may be added in an amount of 0.05 to 2 parts by weight with respect to 100 parts in total. As the produced elastomer used in the (a) carboxyl group-containing elastomer of the present invention,
Generally, those having a number average molecular weight of 1500 to 500,000 and an acid value of 30 to 700 are used.

The terminal ethylenically unsaturated compound of (b) is
It is an ethylenically unsaturated compound containing at least one terminal ethylene group, and examples thereof include esters of acrylic acid and methacrylic acid, and esters of unsaturated dicarboxylic acids. Esters of acrylic acid and methacrylic acid, especially with polyols such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, glycerol di (meth) acrylate, propanediol di (meth) acrylate, butanediol di ( (Meth) acrylate, cyclohexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and the like are preferable, and examples of the unsaturated dicarboxylic acid ester include fumaric acid diethyl ester and fumaric acid. Examples thereof include acid dibutyl ester, fumaric acid dioctyl ester, and maleic acid dibutyl ester.

Other unsaturated compounds such as N-methylmaleimide, diallyl phthalate, triallyl cyanurate, hexamethylene diacrylamide and divinylbenzene can also be used. When a carboxyl group-containing ethylenically unsaturated compound obtained by reacting a hydroxyl group-containing unsaturated compound such as hydroxyethyl (meth) acrylate with a dicarboxylic acid anhydride such as maleic anhydride is used, the solubility in alkali Will increase. These may be used alone or in combination of two or more.

Examples of the photopolymerization initiator (c) include benzophenones such as benzophenone, chlorobenzophenone, benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzyl alkyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal. , Anthraquinones, for example, anthraquinone, 2-chloroanthraquinone, thioxanthones, Michler's ketones and the like.

In the photosensitive resin composition of the present invention,
The component (a) is 10 to 90% by weight, preferably 20 to 8
0% by weight, the component (B) is 1 to 40% by weight, preferably 5
˜30 wt%, component (c) is 0.001 to 5 parts by weight,
It is preferably used by blending in the range of 0.1 to 3% by weight.

The photosensitive resin composition of the present invention may contain, as an optional component, a hydrophilic polymer or an elastomer having no substituent. A hydrophilic polymer is one that is soluble or swellable in water or a developer containing an alkaline aqueous solution, and has a hydroxyl group, a carboxyl group, an amino group, a sulfonic acid group, or a hydrophilic ether group such as polyethylene glycol. Is to have. For example, polyvinyl alcohol, hydroxyethyl cellulose, polyacrylic acid, polyacrylamide, polyethylene oxide, aqueous urethane resin, water-soluble epoxy compound, water-soluble polyester, carboxyl-containing polybutadiene, carboxyl-containing butadiene acrylonitrile copolymer, carboxyl-containing styrene-butadiene copolymer, etc. Is mentioned. These are used in 70% by weight or less, preferably 50% by weight or less of the total composition.

Examples of the elastomer include a butadiene polymer, an isoprene polymer, a chloroprene polymer, a styrene / butadiene copolymer, a styrene / isobrene copolymer, a styrene / butadiene / styrene block copolymer, and a styrene / isoprene / styrene block copolymer. Examples thereof include polymers, acrylonitrile / butadiene copolymers, epichlorohydrin rubbers, acrylic rubbers, and the like. These are used in 70% by weight or less of the total composition, preferably 50% by weight or less.

In the composition of the present invention, a thermal polymerization inhibitor can generally be added. For example, 2,6-di-t-butyl-p-cresol, p-methoxyphenol, hydroquinone, t-butylcatechol, t-butylhydroxyanisole and the like can be mentioned. These are used by blending 0.001-2% by weight based on the total composition.

A plasticizer may be added to the composition of the present invention if necessary. This plasticizer assists in molding the photosensitive resin, promotes the removal of the unexposed portion, and increases the flexibility of the cured resin. Such things include naphthenic oil,
Paraffin oil, polyethylene glycol, polyethylene glycol ester, low molecular weight rubber, for example, liquid polybutadiene, liquid polyacrylonitrile butadiene, liquid polystyrene butadiene, liquid polyisoprene and the like can be mentioned. Further, a plasticizer such as triphenyl phosphate, dioctyl phthalate, dioctyl adipate, octyl diphenyl phosphate, tributoxyethyl phosphate and the like can be blended. The amount of these plasticizers is preferably 20% by weight or less based on the total composition.

To mold the photosensitive resin composition of the present invention into a photosensitive printing plate, each component is dissolved and mixed in a solvent, and then the solvent is removed to mold to a required thickness, or each component is kneadered, After mixing with a roll mill or the like, it is carried out by molding into a predetermined thickness by hot press molding, calendering or extrusion molding. The composition can be provided with a thin film laminate layer of polyethylene, polypropylene, polyester, polystyrene, or the like on the surface. The film is stripped after exposure. A resin film soluble in an aqueous developer may be used for the surface lamination. At this time, the laminate layer is also removed when developing after exposure.

In order to cure the photosensitive printing plate using the photosensitive resin composition of the present invention, it is preferable to use ultraviolet rays in the wavelength range of 150 to 500 nm, preferably 300 to 400 nm. The light source is preferably a high or low pressure mercury lamp, a fluorescent lamp for ultraviolet rays, a xenon lamp or a zirconium lamp.
A negative film having a transparent image is applied to a photosensitive resin plate composed of the composition of the present invention, and the non-image area which is not exposed after being exposed by exposure to ultraviolet rays from the light source is removed by using a developing solution to obtain a relief image. .. The developer may contain tap water as a main component, an alkaline compound such as sodium hydroxide and sodium carbonate, a surfactant, a water-soluble organic solvent and the like. The developer is used at a liquid temperature of 25 to 45 ° C., but it may be used at 50 to 70 ° C. in order to enhance the developability. The photosensitive resin plate obtained by the composition of the present invention has rubber elasticity and excellent properties as a flexographic plate, but it can also be applied to photoresists and screens for screen printing.

[0020]

EXAMPLES The present invention will be described in more detail with reference to experimental examples. Synthesis Example 1 Polybutadiene containing both end hydroxyl groups having a number average molecular weight of 2750 and a hydroxyl group content of 0.83 meq / g in a 1 liter separable flask equipped with a stirrer, a nitrogen introducing tube, and a reflux condenser (trade name: Polybd R 45T, Idemitsu Petrochemical Made) 14
A 1/1 copolymer of styrene and maleic anhydride having a number average molecular weight of 1600 and an acid value of 480 per 3 g (trade name: SMA100
0, manufactured by ARCO Chemical) was charged. The temperature was gradually raised with stirring in a nitrogen stream, and when the temperature reached 180 ° C., the temperature was maintained for 1 hour to complete the esterification reaction, and then the resin was extracted into a metal pan and cooled. The resin produced has a number average molecular weight of 24,000 and an acid value of 170.
Met.

Synthesis Example 2 Polybutadiene (trade name: Polybd R 15T) having hydroxyl groups at both ends having a number average molecular weight of 1250 and a hydroxyl group content of 1.83 meq / g was placed in a 1 liter separable flask equipped with a stirrer, a nitrogen introducing tube and a reflux condenser. , Made by Idemitsu Petrochemical) 10
A 2/1 copolymer of styrene and maleic anhydride having a number average molecular weight of 1700 and an acid value of 350 per 0 g (trade name: SMA200
0, manufactured by ARCO Chemical Co., Ltd.) 205 g was charged. The temperature was gradually raised with stirring in a nitrogen stream, and when the temperature reached 170 ° C., the temperature was maintained for 1 hour to complete the esterification reaction, and then the resin was extracted into a metal pan and cooled. The resin produced has a number average molecular weight of 81,000 and an acid value of 198.
Met.

Synthesis Example 3 A polybutadiene having a number average molecular weight of 2750 and a hydroxyl group content of 0.83 meq / g (both trade names: Polybd R 45T) was placed in a 1 liter separable flask equipped with a stirrer, a nitrogen introducing tube, and a reflux condenser. , Made by Idemitsu Petrochemical) 10
A 1/1 copolymer of isobutene and maleic anhydride having a number average molecular weight of 6000 and an acid value of 650 per 0 g (trade name Isoban 0
(4, made by Kuraray) 145 g was charged. The temperature was gradually raised with stirring in a nitrogen stream, and when the temperature reached 170 ° C., the temperature was maintained for 1 hour to complete the esterification reaction, and then the resin was extracted into a metal pan and cooled. The resulting resin had a number average molecular weight of 21,500 and an acid value of 365.

Synthesis Example 4 Polybutadiene (Brand name: Polybd R 45T) having both end hydroxyl groups having a number average molecular weight of 2750 and a hydroxyl group content of 0.83 meq / g was placed in a 1 liter separable flask equipped with a stirrer, a nitrogen introducing tube and a reflux condenser. , Idemitsu Petrochemical) 14
3g and 19g ethylene glycol, number average molecular weight 16
00, acid number 480 and 1/1 of maleic anhydride
Copolymer (trade name: SMA1000, ARCO Chem
(made by ical). The temperature was gradually raised with stirring in a nitrogen stream, and when the temperature reached 180 ° C., the temperature was maintained for 1 hour to complete the esterification reaction, and then the resin was extracted into a metal pan and cooled. The produced resin had a number average molecular weight of 25,000 and an acid value of 92.

Synthesis Example 5 Polybutadiene containing both end hydroxyl groups having a number average molecular weight of 2750 and a hydroxyl group content of 0.83 meq / g (trade name: Polybd R 45T) was placed in a 1 liter separable flask equipped with a stirrer, a nitrogen introducing tube, and a reflux condenser. , Made by Idemitsu Petrochemical) 10
4.75 g of tolylene diisocyanate and 0.1 g of dibutyltin dilaurate were added to 0 g and reacted at 150 ° C. for 30 minutes to produce a hydroxyl group-terminated urethane prepolymer. 1/1 copolymer (trade name SMA1000,
30 g of ARCO Chemical) was charged. The temperature was gradually raised with stirring in a nitrogen stream, and when the temperature reached 180 ° C., the temperature was maintained for 1 hour to complete the esterification reaction, and then the resin was extracted into a metal pan and cooled. The produced resin had a number average molecular weight of 17,000 and an acid value of 95.

Example 1 85 parts of the carboxyl group-containing elastomer obtained in the synthesis example,
15 parts of tetraethylene glycol dimethacrylate,
2,2-dimethoxy-2-phenylacetophenone 2
And 0.2 part of 2,6-di-t-butyl-p-cresol were kneaded with a kneader. This mixture was sandwiched between 100 μm polyester films, placed inside a spacer having a thickness of 3 mm, and pressed at 140 ° C. to obtain a sheet of a photosensitive resin composition.

Next, the polyester film on one side was peeled off, a transparent image carrier on which an image was drawn was placed on the surface, and exposed for 30 minutes with an ultraviolet fluorescent lamp at a light intensity of 2.5 mW / cm ² . Excluding the image carrier, 0.3 parts of sodium hydroxide,
2- (2-Butoxy) ethoxyethanol 7 parts, water 93
Part of the solution was used to elute the unexposed part with a brush at a liquid temperature of 60 ° C. for 20 minutes to obtain a relief faithfully reproducing the original image. This flexographic plate was used to print with an alcohol-based ink and the plate showed sufficient resistance to the ink.

Examples 2 to 5 A photosensitive resin composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing elastomer obtained in each Synthesis Example 2-5 was used instead of the carboxyl group-containing elastomer in Synthesis Example 1. Got the sheet. Exposure and development are performed in the same manner as in Example 1,
A relief that faithfully reproduces the original image was obtained. This flexographic plate was used to print with an alcohol-based ink and the plate showed sufficient resistance to the ink.

Example 6 Carboxyl group-containing elastomer 45 obtained in Synthesis Example 1
Parts, styrene-butadiene-styrene block copolymer (trade name: Kraton 1101, manufactured by Shell Chemical Co., Ltd.) 40 parts,
Dioctyl fumarate 15 parts, 2,2-dimethoxy-2-
Phenylacetophenone 2 parts, 2,6-t-butyl-p
-0.2 parts of cresol was kneaded with a kneader, and then a photosensitive resin composition sheet was obtained in the same manner as in Example 1.
Exposure and development were performed in the same manner as in Example 1 to obtain a relief that faithfully reproduced the original image. This flexographic plate was used to print with an alcohol-based ink and the plate showed sufficient resistance to the ink.

Comparative Example 1 85 parts of a copolymer having a number average molecular weight of 40,000 prepared by mixing and polymerizing butadiene / styrene / methyl methacrylate / methacrylic acid = 45/10/20/25, and tetraethylene glycol dimethacrylate. 15 copies, 2, 2
-Dimethoxy-2-phenylacetophenone 2 parts, 2,
0.2 part of 6-di-t-butyl-p-cresol was kneaded with a kneader. This mixture was sandwiched between 100 μm polyester films, placed inside a spacer having a thickness of 3 mm, and pressed at 140 ° C. to obtain a sheet of a photosensitive resin composition.

Next, the polyester film on one side was peeled off, a transparent image carrier on which an image was drawn was placed on the surface, and exposure was carried out for 30 minutes using an ultraviolet fluorescent lamp with light having an intensity of 2.5 mW / cm ² . Excluding the image carrier, 0.3 parts of sodium hydroxide,
2- (2-Butoxy) ethoxyethanol 7 parts, water 93
Part of the solution was used to elute the unexposed area with a brush at a liquid temperature of 60 ° C. for 20 minutes. However, the exposed area also had a high swelling rate in an alkaline aqueous solution and a relief with sufficient resolution was not obtained. This flexographic plate was used to print with an alcohol-based ink, but the plate had poor resistance to ink and poor printability.

Comparative Example 2 Carboxylated butadiene / acrylonitrile copolymer (number average molecular weight: 30,000, acrylonitrile content: 27)
%, Carboxyl content 3.4%) 85 parts, tetraethylene glycol dimethacrylate 15 parts, 2,2-dimethoxy-2-phenylacetophenone 2 parts, 2,6-di-
0.2 part of t-butyl-p-cresol was kneaded with a kneader. Thereafter, the same treatment as in Comparative Example 1 was carried out to obtain a sheet of the photosensitive resin composition.

Exposure and development were performed in the same manner as in Comparative Example 1. However, the exposed portion also had a high swelling rate in an alkaline aqueous solution, and a relief with sufficient resolution could not be obtained. Using this flexographic plate, we printed with alcohol-based ink,
The plate had poor resistance to ink and poor printability.

[0033]

INDUSTRIAL APPLICABILITY The photosensitive resin composition of the present invention can be developed with an aqueous developer after exposure and has resistance to alcohol-based ink, and is particularly useful for flexographic printing plates.

Claims (4)

[Claims] 1. (a) Obtained by reacting a hydrocarbon polymer having a hydroxyl group with a copolymer having a carboxyl group (including an acid anhydride group) at a ratio in which the carboxyl group equivalent exceeds the hydroxyl group equivalent. Elastomer containing carboxyl group; 10 to 90% by weight; (B) Terminal ethylenically unsaturated compound; 1 to 40% by weight; (C) Photopolymerization initiator; 0.01 to 10% by weight Resin composition 2. The composition according to claim 1, wherein the hydrocarbon polymer having a hydroxyl group has a number average molecular weight of 500 to 100,000. 3. The composition according to claim 1, wherein the copolymer having a carboxyl group is a copolymer of styrene, isobutylene or acrylic acid ester and maleic anhydride. 4. The composition according to claim 1, wherein the terminal ethylenically unsaturated compound has a carboxylic acid group.