Radiation imagery chemistry: process – composition – or product th – Imaged product – Including resin or synthetic polymer
Patent
1995-09-29
1997-10-21
Hamilton, Cynthia
Radiation imagery chemistry: process, composition, or product th
Imaged product
Including resin or synthetic polymer
4302851, 4302871, 4302861, 430910, 430306, 430907, 4302731, 522109, G03F 7033, G03F 709, G03F 730
Patent
active
056794851
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a photosensitive composition, a photosensitive rubber plate and a process for making the photosensitive rubber plate, and a flexographic printing plate and a process for making the flexographic printing plate. More particularly, this invention relates to (a) a photosensitive composition comprising a phosphorus-containing hydrophilic copolymer and a thermoplastic elastomer, (b) a photosensitive rubber plate which is a laminated product of the photosensitive composition on a support, (c) a flexographic printing plate comprising the rubber plate, and (d) processes for making the rubber plate and the flexographic printing plate.
BACKGROUND ART
As a printing material for flexographic printing, there are known (i) a cast rubber plate made by a process wherein a thermosetting resin is hot-pressed onto an original plate prepared, for example, by etching a metal plate, to make a matrix, and a rubber is charged and pressed in the matrix; and (ii) a photosensitive resin plate made from a photosensitive resin composition comprising a predominant amount of a synthetic rubber such as a styrene-butadiene rubber or an acrylonitrile-butadiene rubber, and a minor amount of a photopolymerizable monomer having terminal. ethylenically unsaturated double bonds.
The cast rubber plate has problems such that a substantially long time is required for making the rubber plate, the production cost is high, and the rubber plate exhibits a poor image reproducibility. The photosensitive resin plate made of a synthetic rubber has poor solvent resistance, abrasion resistance and durability, and deteriorates the working atmosphere because a halogenated hydrocarbon such as 1,1,1-trichloroethane is used.
In recent years, various photosensitive resin compositions for a flexographic printing plate have been proposed to solve the above-mentioned problems (for example, Japanese Unexamined Patent Publication No. 54-110287 and 61-22339). These proposed photosensitive compositions have other problems such that a special developing solution comprising water, an alcohol and an alkali is required for development, and the rate of development is very slow.
A photosensitive resin composition has been proposed which comprises (a) a copolymer derived from a conjugated diolefin, an .alpha.,.beta.-ethylenically unsaturated carboxylic acid and an optional monoolefinically unsaturated monomer, (b) a photopolymerizable unsaturated monomer and (c) a photopolymerization initiator (Japanese Examined Patent Publication No. 59-29849). This photosensitive composition has some beneficial properties over the conventional photosensitive compositions, but processability, and transparency and elasticity at a low temperature of the cured product are poor. Especially in a cold northern district, a printing plate made therefrom becomes hard and is not suitable for a flexographic printing.
To solve the above-mentioned problems, the present inventors have proposed a photosensitive resin composition which comprises (a) a copolymer a conjugated diene, a methacrylate or acrylate having an acidic functional group, and optional monoolefinically unsaturated monomer or a polyfunctional vinyl monomer, (b) a photopolymerizable unsaturated monomer and (c) a photopolymerization initiator (Japanese Unexamined Patent Publication No. 4-67041). Although this photosensitive resin composition provides a cured product exhibiting enhanced transparency and elasticity at a low temperature, the time required for washing the light-exposed plate with an aqueous alkali solution for the dissolution and removal of the resin composition in the light-unexposed areas upon development in the course of making a printing plate is long; and the flexural strength is poor and the printing plate is liable to be cracked when bended.
In recent years, aqueous inks are used instead of inks of a solution form in an organic solvent in flexographic printing to avoid air pollution. The flexographic printing plate used must not be swollen with the aqueous inks. However, in the
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patent: 4177074 (1979-12-01), Proskow
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patent: 5135827 (1992-08-01), Bohm et al.
patent: 5240808 (1993-08-01), Aoshima et al.
No. 11027 "Phosphorus photocrosslinkable polymers", Research Disclosure, Jun. 1973, pp. 72-80.
Konishi Ichiro
Sakurai Fusayoshi
Suzuki Takao
Ueno Haruo
Usui Tatsuo
Hamilton Cynthia
Nippon Zeon Co. Ltd.
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