JP2007047611A - Photosensitive resin composition and photosensitive resin printing plate material for flexographic printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for flexographic printing having excellent physical strength and impact resilience, and excellent in image properties and transparency, and a photosensitive resin printing plate material for flexographic printing obtained by laminating the photosensitive resin composition for flexographic printing. <P>SOLUTION: The photosensitive resin composition for flexographic printing contains as essential components (1) a thermoplastic elastomer, (2) a polyfunctional ethylenically unsaturated compound having at least one carbon atom which is combined with two or more ethylenically unsaturated groups, and (3) a photopolymerization initiator, wherein the thermoplastic elastomer (1) is a thermoplastic elastomer prepared by mixing one or more selected from a styrene-isoprene-styrene copolymer and a styrene-butadiene-styrene copolymer with a styrene-isoprene-butadiene-styrene copolymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photosensitive resin composition for flexographic printing and a photosensitive resin plate material, and more specifically, the photosensitive resin composition for flexographic printing which is excellent in image quality, physical strength and impact resilience and is transparent, and the flexographic printing composition. The present invention relates to a photosensitive resin plate material for flexographic printing in which a photosensitive resin composition for printing is laminated.

  Conventionally, styrene-butadiene-styrene block copolymers and styrene-isoprene-styrene block copolymers have been suitably used as thermoplastic elastomers used in photosensitive resin compositions for flexographic printing. These copolymers are considered to be highly useful elastomers in terms of rubber elasticity, molding processability, and availability. By using these copolymers, many inventions have been created in order to give the photosensitive resin composition various properties, that is, image properties, physical strength, rebound resilience, printability, printability, and the like. .

  In the invention described in Patent Document 1, printability and printability are improved by using a photosensitive resin composition containing an elastomer composed of a mixture of styrene-isoprene-styrene copolymer and styrene-butadiene-styrene copolymer. The purpose is to increase. Patent Document 2 discloses that stickiness of cold flow and plate can be suppressed by using a photosensitive elastomer for flexographic printing composed of a styrene-butadiene thermoplastic elastomer and a styrene-isoprene thermoplastic elastomer. However, although the above-mentioned photosensitive resin composition has physical strength and impact resilience, printability and printability, it has a problem that the photosensitive resin composition lacks transparency.

JP 2001-215697 A JP 2000-181060 A

The present invention has been made by the inventor after extensive research to solve the above problems. That is, the subject of this invention is providing the photosensitive resin composition for flexographic printing which has the outstanding physical strength and impact resilience, and is excellent in image property and transparency.
Another object of the present invention is to provide a photosensitive resin plate material for flexographic printing in which a photosensitive resin composition for flexographic printing having excellent physical strength and impact resilience, and excellent in image quality and transparency is laminated. There is to do.

The invention according to claim 1 is a photosensitive resin composition for flexographic printing comprising the following components (a) to (c) as essential components, wherein (a) the thermoplastic elastomer is a styrene-isoprene-styrene copolymer. A photosensitive resin composition for flexographic printing, which is a thermoplastic elastomer obtained by mixing one or more selected from a polymer or a styrene-butadiene-styrene copolymer and a styrene-isoprene-butadiene-styrene copolymer. About.
(A) Thermoplastic elastomer (b) Polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups (c) Photopolymerization initiator The invention according to claim 2 (I) Thermoplastic elastomer is 35 to 95% by weight, (b) Polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups is 1.0 to 30.0. The photosensitive resin composition for flexographic printing according to claim 1, wherein 0.1% to 10.0% by weight of the photopolymerization initiator (%) and (iii) the photopolymerization initiator are contained.

According to a third aspect of the present invention, there is provided (1) one or more selected from styrene-isoprene-styrene copolymer or styrene-butadiene-styrene copolymer contained in the thermoplastic elastomer and styrene-isoprene-butadiene-styrene copolymer. The blending ratio of the polymer is
Styrene-butadiene-styrene copolymer: styrene-isoprene-butadiene-styrene copolymer = 99: 1 to 1:99
Styrene-isoprene-styrene copolymer: styrene-isoprene-butadiene-styrene copolymer = 99: 1 to 1:99 or styrene-butadiene-styrene copolymer: styrene-isoprene-styrene copolymer: styrene-isoprene- Butadiene-styrene copolymer = 1-98: 1-98: 1-98
It is related with the photosensitive resin composition for flexographic printing of Claim 1 or 2 characterized by the above-mentioned.
The invention according to claim 4 is a photosensitive resin plate material for flexographic printing, comprising the photosensitive resin composition for flexographic printing according to any one of claims 1 to 3 and a support, and is provided on the surface of the support. The present invention relates to a photosensitive resin plate material for flexographic printing in which the photosensitive resin composition for flexographic printing is laminated.
The invention according to claim 5 relates to a printed matter printed using the photosensitive resin plate material for flexographic printing according to claim 4.

The photosensitive resin composition for flexographic printing of the present invention has excellent physical strength and impact resilience, and is excellent in image quality and transparency.
Since the photosensitive resin plate material for flexographic printing of the present invention is formed by laminating the photosensitive resin composition for flexographic printing of the present invention, it has excellent physical strength and impact resilience, as well as excellent image quality and transparency. Therefore, it is highly useful for high-speed printing and process printing required for label printing.

First, the photosensitive resin composition for flexographic printing of the present invention will be described.
The photosensitive resin composition for flexographic printing of the present invention comprises the following (A) to (C) as essential components.
(B) Thermoplastic elastomer (b) Polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups (c) Photopolymerization initiator

  The (a) thermoplastic elastomer according to the present invention is a kind selected from a styrene-isoprene-styrene copolymer (hereinafter also referred to as SIS) or a styrene-butadiene-styrene copolymer (hereinafter also referred to as SBS). A thermoplastic elastomer comprising the above and a styrene-isoprene-butadiene-styrene copolymer (hereinafter sometimes referred to as SIBS).

  The SIS and SBS used in the present invention are excellent in rubber elasticity and molding processability, and are easily available. The number average molecular weights of these triblock copolymers are in the range of 2,000 to 100,000 for non-elastomeric blocks and 250,000 to 1,000,000 for elastomer blocks as measured by GPC using polystyrene as a standard substance. It is desirable. The reason is that if the above range is exceeded, the performance of the photosensitive resin composition deteriorates. That is, if the molecular weight of the non-elastomeric block is too small, cold flow properties remain in the composition, and if it is too large, rubber elasticity is impaired. If the molecular weight of the elastomer block is small, it is difficult to obtain rubber elasticity, and if it is too large, the cold flow property is high.

  In the SIBS used in the present invention, the number average molecular weight of the tetrablock copolymer is 2,000 to 200,000 for a non-elastomeric block and 250,000 to 2,000 for an elastomer block in GPC measurement using polystyrene as a standard substance. It is desirable to be in the range of 000,000. The reason is that if the above range is exceeded, the performance of the photosensitive resin composition deteriorates. That is, if the molecular weight of the non-elastomeric block is too small, cold flow properties remain in the composition, and if it is too large, rubber elasticity is impaired. If the molecular weight of the elastomer block is small, it is difficult to obtain rubber elasticity, and if it is too large, the cold flow property is high.

When SBS and SIBS are mixed as (i) the thermoplastic elastomer according to the present invention, the blending ratio is preferably SBS: SIBS = 99: 1 to 1:99, more preferably SBS: SIBS = 5: 95-95: 5.
When SIS and SIBS are mixed as (i) the thermoplastic elastomer according to the present invention, the blending ratio is preferably SIS: SIBS = 99: 1 to 1:99, more preferably SIS: SIBS = 5: 95-95: 5.
When SBS, SIS and SIBS are mixed as the thermoplastic elastomer (a) according to the present invention, the blending ratio is desirably SBS: SIS: SIBS = 1 to 98: 1 to 98: 1 to 98, more preferably. Is SBS: SIS: SIBS = 5-90: 5-90: 5-90.
The photosensitive resin composition for flexographic printing using (a) thermoplastic elastomer having the above blending ratio is preferable because it has excellent physical strength and rebound resilience and is excellent in image quality and transparency.

  The blending amount of (a) the thermoplastic elastomer in the photosensitive resin composition for flexographic printing of the present invention is 35.0 to 95.0% by weight, and more preferably 50 to 80% by weight. The reason is that when it is less than 35.0% by weight, the physical strength is inferior, and when it exceeds 95.0% by weight, the productivity is inferior and the desired hardness cannot be obtained. Because.

  (B) a polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups according to the present invention (hereinafter sometimes referred to as (b) a polyfunctional ethylenically unsaturated compound) Is, for example, dimethacrylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, polyethylene glycol dimethacrylate; diethylene glycol diacrylate, 1,3-butylene glycol diacrylate, tripropylene glycol Acrylate, 1,4-butanediol acrylate, neopentyl glycol diacrylate, 1,6-hexanediol acrylate, 1,9-nonanediol acrylate, polyethylene glycol dia Diacrylates such as relates; Divinyl compounds such as divinylbenzene; Bifunctional ethylenically unsaturated compounds such as trimethacrylates such as trimethylolpropane trimethacrylate; Triacrylates such as trimethylolpropane triacrylate And the like, and trifunctional ethylenically unsaturated compounds such as pentaerythritol tetraacrylate are preferably used.

  The (b) polyfunctional ethylenically unsaturated compound according to the present invention mentioned above is blended alone or in admixture of two or more in the photosensitive resin composition for flexographic printing of the present invention. When used as a mixture, a mixture of 1,6-hexanediol diacrylate and 1,9-nonanediol diacrylate, and a mixture of 1,6-hexanediol dimethacrylate and trimethylpropane triacrylate are preferable. The photosensitive resin composition for flexographic printing according to the present invention in which the polyfunctional ethylenically unsaturated compound is mixed and blended is excellent in image quality, physical strength, and impact resilience. The photosensitive resin composition for flexographic printing of the present invention may further contain fumaric acid, maleic acid ester, allyl ester, and the like for fine adjustment of printability.

  The blending amount of the (b) polyfunctional ethylenically unsaturated compound in the photosensitive resin composition for flexographic printing of the present invention is 1.0 to 30.0% by weight, and 5.0 to 10.0% by weight. More preferred. The reason for this is that when the amount is less than 1.0% by weight, the crosslink density is lowered and the physical strength is inferior, and when it exceeds 30.0% by weight, the resilience is inferior, which is not preferable in any case. .

As the (c) photopolymerization initiator according to the present invention, a known benzoin derivative or hydrogen abstraction type benzophenone derivative, which is a compound that undergoes α-cleavage, can be used. It is suitably used in the present invention.
(C) Examples of the photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin dimethyl ketal, benzophenone / dimethylethanolamine mixture, and thioxanthone / dimethylethanolamine mixture.

  The blending amount of the photopolymerization initiator (c) in the photosensitive resin composition for flexographic printing of the present invention is 0.1 to 10.0% by weight, and more preferably 1.0 to 3.0% by weight. The reason for this is that when it is less than 0.1% by weight, the crosslinking density is lowered and the physical strength is lowered. This is because if the amount exceeds 10.0% by weight, image absorption is inferior because of a large amount of light absorption in the effective active irradiation region, which is not preferable in either case.

  The photosensitive resin composition for flexographic printing of the present invention optionally contains a plasticizer, an ultraviolet absorber, a polymerization inhibitor, a dye, inorganic fine particles, etc. in addition to the essential components (a) to (c) described above. Can be added. Examples thereof include hydrocarbon oils such as naphthenic oil and paraffin oil, low molecular polystyrene having a molecular weight of 3,000 or less, petroleum resin, liquid 1,2-polybutadiene, and 1,4-polybutadiene. The polypentadiene and the like are useful for adjusting the hardness of the printing plate and improving the workability during molding.

Next, the photosensitive resin plate material for flexographic printing of the present invention will be described.
The photosensitive resin plate material of the present invention comprises at least a support and the photosensitive resin composition of the present invention.

  As the support, a plastic plate, an aluminum plate, or the like can be used, and a polyethylene terephthalate film, a urethane film, a polyethylene film, a polypropylene film, or the like is preferable. Among these, a polyethylene terephthalate film is preferably used.

  A preferred embodiment of the photosensitive resin plate material for flexographic printing of the present invention has a three-layer structure. FIG. 1 is a perspective view of the photosensitive resin plate material of the present invention having this three-layer structure, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1 and 2, (1) is a photosensitive resin plate material of the present invention having a three-layer structure, (2) is a support, (3) is a photosensitive resin composition of the present invention, and (4) is A cover film is shown. This cover film is effective for improving plate-making workability, protecting the plate surface and preventing scratches.

  1 and 2, (2) The thickness of the support is preferably 75 to 200 μm, more preferably 100 to 200 μm. (3) The thickness of the photosensitive resin composition is preferably 0.5 to 10.0 mm, and more preferably 1.0 to 9.0 mm. (4) The thickness of the cover film is preferably 75 to 200 μm, more desirably 100 to 200 μm.

Hereinafter, a series of manufacturing methods for manufacturing a photosensitive resin plate material for flexographic printing using the photosensitive resin composition for flexographic printing of the present invention will be described.
The photosensitive resin composition for flexographic printing of the present invention comprises at least the essential components (A) to (C) at 90 to 150 ° C., preferably 110 to 140 ° C. for 40 to 90 minutes, preferably After kneading for 40 to 60 minutes, the plate material can be produced by a method of extrusion molding with a hot press.

  The present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

(Manufacture of photosensitive resin plate material)
Hereinafter, thermoplastic elastomer based on the composition of Table 1, liquid 1,2-polybutadiene [manufactured by Nippon Soda Co., Ltd., Nisso PB1000 (average molecular weight 1000)] 25 parts by weight, 1,6-hexanediol diacrylate 3 as a predetermined amount of acrylic monomer 0.0 part by weight, 2.0 parts by weight of 1,9-nonanediol diacrylate, 1.5 parts by weight of 2,2-dimethoxy-2-phenyl-acetophenone, 0.5 parts by weight of 2,6-di-t-butylcresol The part is put into a kneader and kneaded at a temperature of 110 to 140 ° C. for 60 minutes. The photosensitive resin composition thus prepared was fed from a raw material inlet of an extrusion molding machine whose barrel temperature was kept at 120 ° C. through a quantitative supply device kept at 120 ° C. The photosensitive composition discharged from the base part is sandwiched between a cover film (PET film pre-coated with a polyamide resin 4 μm release agent) and a support (PET film pre-coated with a urethane adhesive), and a plate A gap between the two forming rolls was set in advance so as to match the thickness, and the sheet was formed into a sheet by passing through this gap. After cooling, a photosensitive resin plate material (Examples 1 to 3 and Comparative Examples 1 to 3) was obtained by cutting into a predetermined size. The numbers in Table 1 indicate “parts by weight”.

  The photograph of Examples 1-3 is shown in FIG. 3, and the photograph of the photosensitive resin plate material of Comparative Examples 1-3 is shown in FIG. It can be seen that Examples 1 to 3 in FIG. 3 are excellent in transparency, and that Comparative Examples 1 and 3 in FIG. 4 are also highly transparent, and Comparative Example 2 in FIG. 4 is inferior in transparency.

(Evaluation of photosensitive resin plate material)
About Examples 1-3 and Comparative Examples 1-3, the following tests and evaluations were performed and the results are shown in Table 2. Tests and evaluations other than the cold flow presence / absence evaluation shown below were evaluated according to the following (evaluation criteria).

<Rebound resilience test>
In the relief plates for flexographic printing after the plate making of Examples 1 to 3 and Comparative Examples 1 to 3, evaluation was performed using a rebound resilience tester based on JIS K 6301-11.

<Evaluation of image quality>
This photosensitive flexographic printing plate precursor is placed on the support side for 2 minutes by JE-AO-HSH (manufactured by JEOL Ltd .: exposure unit) in which 32 JL-40SPRCs (manufactured by JEOL Ltd .: chemical lamp) are installed. Back exposed. After that, the cover film is peeled off, and a negative film for image reproducibility evaluation (for example, 150% 3% dot, diameter 200 μm independent point, width 50 μm thin line) is vacuum-adhered on the photosensitive resin layer, and the same chemical lamp After exposure for 10 minutes from the negative film side, Lunasolv II (manufactured by JEOL Ltd.) was washed as a developer using JW-AO-SDR (JEOL Seiki Co., Ltd .: rotary type washer), and again It dried and evaluated for 40 minutes in the oven heated at 60 degreeC.

(Evaluation criteria)
◯: Good reproducibility △: Width 50 μm fine line poor development ▲: Diameter 200 μm independent point, width 50 μm thin line reproducibility ×: 150 line 3% halftone dot, diameter 200 μm independent point, width 50 μm thin line reproducibility

<Evaluation of presence or absence of tack>
The tack measurement of the relief printing plate surface was performed using a tack tester manufactured by Toyo Seiki Seisakusho. The tack measurement was performed at 20 ° C. by bringing a smooth portion of the sample pieces of Examples 1 to 3 and Comparative Examples 1 to 3 into contact with a portion of a 13 mm wide aluminum ring having a radius of 50 mm and a width of 13 mm. A load of 5 kg was applied and left for 4 seconds, and then the aluminum wheel was pulled up at a constant speed of 30 mm per minute, and the pulling resistance when the aluminum wheel separated from the sample pieces of Examples 1 to 3 and Comparative Examples 1 to 3 was pushed and pulled. Read with a gauge. The larger this value, the greater the stickiness.

(Evaluation criteria)
○: Less than 150 N / m Δ: 150 N / m or more and less than 200 N / m ▲: 200 N / m or more and less than 250 N / m ×: 250 N / m or more

<Evaluation of cold flow>
The presence or absence of cold flow was evaluated to confirm the change in shape. Each method and comparative example (1.7 mm × 100 mm × 100 mm) was held at 1 kg caustic and 40 ° C. for 1 week, and the protrusion width of the resin from the support such as a film was measured. Cold flow resistance evaluation was performed according to the evaluation criteria.

(Evaluation criteria)
○: 0.0 mm
Δ: More than 0.0 mm and 0.5 mm or less ▲: More than 0.5 mm and 1.0 mm or less ×: More than 1.0 mm

<Hardness test>
In the relief plate for flexographic printing after plate making, evaluation was performed using a hardness measuring instrument in accordance with JIS K 6301.

  From the results shown in Table 2, Examples 1 to 3 are excellent in all tests and evaluation results of resilience, image quality, presence / absence of tack, and shape change as compared with Comparative Examples 1 to 3, and extremely useful. Is high.

It is a schematic perspective view of the photosensitive resin plate material in this invention. It is AA 'sectional drawing of FIG. It is a photograph of the photosensitive resin plate material of Examples 1-3 in this invention. It is a photograph of the photosensitive resin plate material of Comparative Examples 1-3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive resin plate material 2 Support body 3 Photosensitive resin composition 4 Cover film

Claims (5)

A photosensitive resin composition for flexographic printing comprising the following (a) to (c) as essential components, wherein (a) the thermoplastic elastomer is a styrene-isoprene-styrene copolymer or a styrene-butadiene-styrene copolymer. A photosensitive resin composition for flexographic printing, which is a thermoplastic elastomer obtained by mixing at least one selected from polymers and a styrene-isoprene-butadiene-styrene copolymer.
(B) Thermoplastic elastomer (b) Polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups (c) Photopolymerization initiator   The (i) thermoplastic elastomer is 35 to 95% by weight, and (b) the polyfunctional ethylenically unsaturated compound having at least one carbon atom bonded to two or more ethylenically unsaturated groups is 1.0 to 30. 2. The photosensitive resin composition for flexographic printing according to claim 1, comprising 0 wt% and (c) 0.1 to 10.0 wt% of the photopolymerization initiator. The blending ratio of one or more selected from styrene-isoprene-styrene copolymer or styrene-butadiene-styrene copolymer and styrene-isoprene-butadiene-styrene copolymer contained in the thermoplastic elastomer (a)
Styrene-butadiene-styrene copolymer: styrene-isoprene-butadiene-styrene copolymer = 99: 1 to 1:99
Styrene-isoprene-styrene copolymer: styrene-isoprene-butadiene-styrene copolymer = 99: 1 to 1:99 or styrene-butadiene-styrene copolymer: styrene-isoprene-styrene copolymer: styrene-isoprene- Butadiene-styrene copolymer = 1-98: 1-98: 1-98
The photosensitive resin composition for flexographic printing according to claim 1, wherein the composition is a photosensitive resin composition for flexographic printing.   A photosensitive resin plate material for flexographic printing comprising the photosensitive resin composition for flexographic printing according to claim 1 and a support, wherein the photosensitive resin composition is laminated on the surface of the support. A photosensitive resin plate material for flexographic printing. 5. A printed matter printed using the photosensitive resin plate material for flexographic printing according to claim 4.

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