Radiation imagery chemistry: process – composition – or product th – Imaged product – Including resin or synthetic polymer
Patent
1997-03-28
2000-02-15
Codd, Bernard
Radiation imagery chemistry: process, composition, or product th
Imaged product
Including resin or synthetic polymer
4302811, 4302861, 4302871, 430306, 522110, G03F 7033, G03F 7038, G03F 711
Patent
active
060250984
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a photosensitive rubber plate and a photosensitive composition. More particularly, the present invention relates to a photosensitive rubber plate which is superior in transparency and strength balance and high in rate of washing with water after light exposure, as well as to a photosensitive composition used for obtaining the rubber plate.
BACKGROUND ART
Flexographic printing plates are produced by tightly fitting a negative film onto a photosensitive plate, applying an actinic ray thereto to expose part of the photosensitive layer of the plate to the ray, and washing and removing the unexposed portion of the photosensitive layer to form a relief. The solvent used for washing the unexposed portion is currently being converted from a conventional organic solvent into an aqueous solvent which is low in fear of environmental pollution.
The material for photosensitive layer of photosensitive rubber plate such as used in flexographic printing plate is required to have excellent transparency (which enables penetration of light to the interior of photosensitive layer), excellent balance between tight fittability onto material to be printed and strength of plate (the balance is hereinafter referred to as strength balance, in some cases) and high rate of washing with water (which enables easy formation of relief after light exposure).
As the material for photosensitive layer, there is known a photosensitive elastomer composition comprising a thermoplastic elastomer (e.g. styrene-butadiene block copolymer or styrene-isoprene block copolymer), a hydrophilic copolymer (these elastomer and copolymer are main components), a photopolymerizable ethylenically unsaturated monomer and a photopolymerization initiator.
Photosensitive rubber plates using the above photosensitive elastomer composition, however, are inferior in transparency and strength balance and low in rate of washing with water after light exposure.
DISCLOSURE OF THE INVENTION
The present invention has an object of providing a photosensitive rubber plate which is superior in transparency and strength balance and high in rate of washing with water after light exposure, and a photosensitive composition used for obtaining the rubber plate.
The present inventors made a study in order to achieve the above object and found out that a photosensitive rubber plate using a photosensitive composition comprising a hydrophilic copolymer and a styrene-butadiene-styrene type block copolymer having a high vinyl bond content in the conjugated diene monomer unit moiety, is superior in transparency and strength balance and high in rate of washing with water after light exposure. The present invention has been completed based on the above finding.
According to the present invention, there is provided a photosensitive composition comprising: block A consisting of a polymer containing 95% by weight or more of an aromatic vinyl monomer unit and at least one polymer block B consisting of a conjugated diene polymer containing 20% by weight or more of a conjugated diene monomer unit and having a vinyl bond content in the conjugated diene monomer unit moiety, of 15-70%, block copolymer and the hydrophilic copolymer being 100 parts by weight, monomer, and
According to the present invention, there is also provided a photosensitive rubber plate of laminated structure, comprising a substrate and a layer of the above photosensitive composition, formed on the main surface of the substrate.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is described in detail below.
The photosensitive composition of the present invention comprises a block copolymer, a hydrophilic copolymer, a photopolymerizable ethylenically unsaturated monomer and a photopolymerization initiator.
The block copolymer, which is the first component of the present photosensitive composition, has a polymer block A consisting of a polymer containing an aromatic vinyl monomer as a main constituent unit and a polymer block B consisting of a conjugated diene p
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patent: 5348844 (1994-09-01), Wagner
patent: 5422225 (1995-06-01), Southwick et al.
patent: 5679485 (1997-10-01), Suzuki et al.
patent: 5863704 (1999-01-01), Sakurai et al.
Sakurai Fusayoshi
Ueno Haruo
Codd Bernard
Nippon Zeon Co., Ltd
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