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LITHOGRAPHIC MASTER-MAKING BASED ON PHOTODIMERIZATION OF ANTHRACENE GROUPS IN POLYMERS

IP.com Disclosure Number: IPCOM000023164D
Original Publication Date: 1976-Dec-31
Included in the Prior Art Database: 2004-Mar-27

Publishing Venue

Xerox Disclosure Journal

Abstract

There is described a method for making lithographic masters which exploits the property that reversible dimerization of anthracene groups in anthracene containing polymers is accompanied by changes in surface energy and wetting properties of the polymer surface. This effect can be explained by the dependence of the surface energy on the molecular weight of the polymer (in the case of inter-~moleculardimerization, the molecular weight increases to infinity) by chemical change of the material and by other conformational changes which control the type and relative allowance of groups exposed to the surface, The light~inducedchange in the surface properties can be utilized in selective inking and in lithographic applications~ For example, poly[l~~(2~anthryl) ethylmethacrylate-~co-~methylmethacrylate1is solvent cast from tetrahydrofuran on an aluminum substrate, The solvent is evaporated and the dry film is exposed imagewise to the dimerizing radiation (near 360 nanometers), The film is then sprayed with or otherwise wet with solvent such as tetrahydrofuran and a clear image is developed, The solvent wets, swells and finally dissolves the nonexposed areas while the surface of the irradiated areas behaves as a t~releasing surface, In this manner, solvent based inks can be selectively applied on the surface,