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
1996-09-04
1998-12-01
Hamilton, Cynthia
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
522 96, G03F 7027
Patent
active
058436227
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to a liquid photo-sensitive resin composition for use in forming a relief structure. More particularly, the present invention is concerned with a liquid photosensitive resin composition for use in forming a relief structure, comprising (A) an unsaturated polyurethane prepolymer comprising a plurality of diol segments linked through a urethane linkage and having an addition-polymerizable ethylenically unsaturated group at both terminals thereof, the plurality of diol segments comprising at least one polyester diol segment and at least one polyether diol segment, wherein the weight ratio of the at least one polyester diol segment to the at least one polyether diol segment is from 1:3 to 4:1, and wherein each of the at least one polyester diol segment is independently a polyester diol segment obtained by a polycondensation between a diol, which is comprised mainly of 3-methyl-1,5-pentane diol, and a dicarboxylic acid, or a polyester diol segment obtained by a ring-opening polymerization of a lactone comprised mainly of .beta.-methyl-.delta.-valerolactone, (B) an addition-polymerizable ethylenically unsaturated monomer, and (C) a photopolymerization initiator. When the liquid photosensitive resin composition of the present invention is used for producing a relief structure, the occurrence of the tunnel phenomenon in the relief portions of a relief structure can be effectively suppressed, so that a relief structure in which the relief portions have no defect can be obtained. The liquid photosensitive resin composition of the present invention can be advantageously employed especially for producing a printing plate, such as a flexographic printing plate.
2. Prior Art
In place of conventional rubber printing plates, photoresin printing plates produced from a photosensitive resin have long been used for flexographic printing, such as for corrugated board printing or film printing. In the production of such a photoresin plate, a liquid photosensitive resin, which is in a liquid state before light exposure, is frequently employed because the use of a liquid photosensitive resin is advantageous. For example, a photoresin plate having a desired thickness can be easily produced; removal of the uncured resin is easy; and the removed uncured resin can be recovered and re-used for production of a photoresin plate and, hence, provides an economic advantage. From such a liquid photosensitive resin, a desired printing plate is generally prepared, using a plate-making apparatus, by a method comprising the steps of imagewise exposure, development, post-exposure and drying.
A liquid photosensitive resin for producing a flexographic printing plate is required to have not only low viscosity, good storage stability, good image reproducibility and good developability with an aqueous developer, but also the capability to provide a printing plate having excellent properties, such as high impact resilience, mechanical strength, ink resistance, ink receptivity and ink transferability. One of the important properties, which are especially required for a corrugated board printing plate, is impact resilience. The impact resilience of a corrugated board printing plate is required to be high.
For producing a photoresin relief having not only a good balance of mechanical properties, such as tensile strength, tensile elongation and hardness, but also excellent light stability, a liquid photosensitive resin based on a polyester-polyether polyurethane prepolymer, is widely Publication No. 52-7761 (corresponding to U.S. Pat. No. 3,960,572) and Unexamined Japanese Patent Application Laid-Open Specification No. 4-95959!.
In the production of a relief printing plate from the above-mentioned liquid photosensitive resin based on a polyester-polyether polyurethane prepolymer, it is desired to achieve a large relief depth for the purposes of (1) increasing the amount of an uncured liquid resin which can be recovered and re-used, (2) decreasing the weight of a relief pr
REFERENCES:
patent: 3960572 (1976-06-01), Ibata et al.
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patent: 5336585 (1994-08-01), Takahashi et al.
patent: 5338613 (1994-08-01), Tomotsugu et al.
English translation of Kitayama et al, JP 63-090526 dated 19880421, United States Patent and Trademark Office, Jul. 1997, translated by FLS, Inc., Apr. 1998.
Kobayashi Takashi
Sakata Norihiko
Tomita Hiroaki
Ashai Kasei Kogyo Kabushiki Kaisha
Hamilton Cynthia
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