Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Patent
1979-11-13
1983-02-01
Bowers, Charles L.
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
430152, 430190, 430191, 430157, 430165, 430270, 430281, 430285, 430286, 430287, 430290, 430300, G03C 160, G03C 171, G03F 708
Patent
active
043716024
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
This invention relates to a photosensitive printing plate, and more particularly it relates to an improvement in the photosensitive printing plate having a photosensitive resin layer on a support made of metal or other like material.
BACKGROUND ART
Generally, photosensitive printing plate is manufactured by coating the surface of the support such as aluminum plate, zinc plate, etc., with a photosensitive resin composition after roughening and making hydrophilic the support surface so as to intensify its adhesion to the photosensitive resin composition. The thus manufactured and commercially sold photosensitive printing plate is generally called PS plate.
Such photosensitive printing plate is smooth and flat on its surface, that is, the surface of the photosensitive layer formed from a photosensitive resin composition, so that when a flat original film is placed overlying said layer for effecting exposure and printing, it is found very difficult to purge air out of the space therebetween in a short period of time, and hence a long time would be required for bringing them into close contact with each other. Generally, the original film is placed on the photosensitive printing plate in a vacuum-type contact frame and the air trapped therebetween is sucked out by vacuum to bring them into close attachment. But since air usually stays in the form of independent cells in the non-peripheral areas of the two members, it would take long time to get rid of such air for ensuring close contact of said two members. If exposure is performed in an inperfect stage of contact, there can not be attained reproduction of a picture faithful to the original. For these reasons, reduction of the time required for attaining close contact has been a desideratum in the plate making industry.
As a solution to this problem, it was proposed to provide an uneven layer on the surface of the photosensitive printing plate. For instance, Japanese Patent Laid-Open Nos. 111102/76 and 29302/77 and U.S. Pat. No. 4,126,406 propose the methods for producing uneveness on the photosensitive layer surface by applying thereon a material which can be removed by a developing treatment. These methods, however, complicate the production process as one or more additional steps are involved, that is, the photosensitive composition is first applied on the support and, after drying thereof resin is printed thereon in an uneven pattern, followed by further drying.
Disclosure of Invention
The primary object of this invention is to provide, in an economically advantageous way, a photosensitive printing plate which allows reduction of the time required for effecting perfect attachment and detachment of the photosensitive printing plate and original film to greatly improve the working efficiency for plate making.
The photosensitive printing plate according to this invention is characterized in that a photosensitive composition containing a photosensitive resin and an organic foaming agent is applied on a support to form a photosensitive layer and then said organic foaming agent is thermally decomposed to roughen the surface of said photosensitive layer.
In a preferred form of photosensitive printing plate according to this invention, said organic foaming agent is at least one organic foamable compound selected from the nitroso, sulfonylhydrazine, azo and hydrazo compounds, and such organic foaming agent is contained in an amount of about 3 to 30% by weight based on the photosensitive resin.
In another preferred form of photosensitive printing plate according to this invention, said organic foaming agent is composed of an organic foamable compound and a thermal decomposition assistant, said assistant being contained in the ratio of about 30 to 60% by weight to the organic foamable compound.
A most salient advantage of this invention is that by merely incorporating an organic foaming agent in a photosensitive composition and without requiring addition of any extra step to the normal printing plate making process, there can be o
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Igarashi Junichi
Iwasaki Hidenori
Kasukawa Shunichi
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