IMPROVEMENTS IN AND RELATING TO PHOTOPOLYMERIZABLE COPYING COMPOSITIONS

摘要

1365730 Photoinitiators KALLE AG 7 Dec 1971 [9 Dec 1970] 56746/71 Heading C3P [Also in Division G2] A photopolymerizable composition comprises a binder, a polymerizable vinyl or vinylidene compound and a photoinitiator of the formula R-C#C-CO-R1 where R is a C 1 to C 8 alkyl radical or C 6 to C 10 ) aryl radical, either of which may be substituted, and R1 is a C 6 to C 10 ) aryl radical or C 8 to C 12 aralkenyl radical, which may also be substituted. Preferably R and R1 are mononuclear aromatic radicals, at least one having an alkoxy or alkylenedioxy substituent. The binder is preferably an alkali-soluble or -softenable resin so that non-polymerized parts of the composition can be removed or softened by an alkaline developing agent, such as a sodium phosphate. The monomer may be an acrylate or methacrylate ester, preferably of a polyhydric alcohol. Other additives may also be present, e.g. hydrogen donors, sensitizers, inhibitors and conventional photoinitiators. Examples describe compositions in which the binder is a styrene-maleic anhydride copolymer mixed with one or more of: α-methylstyrenevinyl toluene copolymer, cellulose acetate butyrate, polyvinyl acetate, polyvinyl butyral and polymethyl methacrylate; the monomer is trimethylolpropane triacrylate; and a phenolic inhibitor and/or a dye (Crystal Violet or Pararosaniline) or a polyglycol are included in some cases. The compositions are coated on to plates or films from butanone solution and exposed in a copying device using a xenon lamp.