Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Patent
1992-05-12
1993-10-05
Brammer, Jack P.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
430286, 430288, 430312, 430306, 522116, 522120, 522121, G03C 1725
Patent
active
052503895
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a photosensitive elastomer composition suitable for producing a flexographic printing plate. More particularly, the present invention is concerned with a photosensitive elastomer composition comprising a specific amount of a thermoplastic block copolymer comprising a monovinyl substituted aromatic hydrocarbon polymer block and a conjugated diene polymer block, wherein the monovinyl substituted aromatic hydrocarbon content (A) and the vinyl content (V) of the conjugated diene are, respectively, in specific ranges and the contents (A) and (V) satisfy a specific relationship; an ethylenically unsaturated compound component; and a photopolymerization initiator. The composition of the present invention exhibits excellent photosensitivity. Therefore, when this composition is used to produce, for example, a flexographic printing plate, not only can the time for the plate production be reduced to about half the time which has conventionally been necessary, but also small dots and lines can surely be formed without occurrence of chipping at the time of development, thereby enabling the production of an excellent flexographic printing plate capable of printing fine images.
BACKGROUND ART
Conventionally, a rubber plate for use in flexographic printing has been produced by etching a metallic plate to produce an original plate, preparing a matrix plate from, e.g., a plastic by using the original plate, and pouring a rubber into the matrix plate, followed by pressing. However, this method has drawbacks in that numerous steps are needed, thus requiring too great a cost and too much time. In addition, this method has also drawbacks in that the produced rubber plate itself is low in thickness precision and, hence, it is necessary to raise the thickness precision by shaving the back side of the plate before use.
In order to solve this problem, there has recently been proposed a method of producing a flexographic printing plate from a photosensitive resin composition. According to this method, not only can the step for the above-mentioned shaving of the back side of the plate be eliminated, but also it is possible to obtain a printing plate capable of printing a pattern which is finer, as compared to a pattern which can be printed by the conventional rubber plate.
As these photosensitive elastomer compositions, there are known, for example, those disclosed in Japanese Patent Application Laid-Open Specification No. 47-37521 (corresponding to British Patent No. 1366769), Japanese Patent Application Laid-Open Specification No. 51-106501 (corresponding to U.S. Pat. No. 4045231), Japanese Patent Application Laid-Open Specification No. 52-64301, Japanese Patent Application Laid-Open Specification No. 53-127004 (corresponding to U.S. Pat. No. 4197130), Japanese Patent Application Laid-Open Specification No. 54-110287 (corresponding to U.S. Pat. No. 4177074), Japanese Patent Application Laid-Open Specification No. 55-48744 (corresponding to U.S. Pat. No. 4266005) and Japanese Patent Application Laid-Open Specification No. 58-62640 (corresponding to U.S. Pat. No. 4431723).
Of these, a photosensitive elastomer composition in which a thermoplastic block copolymer is used as a binder (such as those disclosed in Japanese Patent Application Laid-Open Specification Nos. 47-37521 and 53-127004), has very excellent cold-flow resistance in an uncured state and has very excellent rubbery elasticity in a cured state and, hence, such a solid photosensitive elastomer composition has been mainly in practical use for producing a flexographic printing plate. Especially, a photosensitive elastomer composition, such as those disclosed in Japanese Patent Application Laid-Open Specification No. 53-127004 in which fumarate or maleate is used as an ethylenically unsaturated compound, exhibits excellent thermal stability at the time of heat molding for the production of a sheet therefrom and during the storage at high temperatures. Also, a printing plate obtained by using the above-mentioned composition
REFERENCES:
patent: 4045231 (1977-08-01), Toda et al.
patent: 4177074 (1979-12-01), Proskow
patent: 4197130 (1980-04-01), Nakamura et al.
patent: 4266005 (1981-05-01), Nakamura et al.
patent: 4431232 (1984-02-01), Proskow
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patent: 4925775 (1990-05-01), Hoffmann
patent: 4933261 (1990-06-01), Hoffmann
patent: 4959285 (1990-09-01), Hoffmann
Anai Kousi
Nakamura Shohei
Asahi Kasei Kogyo Kabushiki Kaisha
Brammer Jack P.
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