Lithographic printing plate mfr. - by forming protective hardened organo-polysiloxane layer on silicone layer, rendering unprotected areas oleophilic and removing protection

摘要

Process comprises (i) providing patterned protective layer, which is made of hardened layer of photohardening organopolysiloxane, on silicone layer coated on support; (ii) rendering specific areas of the silicone layer, where the protective layer is absent, oleophilic using active chemical species existing in plasma state; and (iii) peeling the protective layer off the silicone layer surface. Photohardening organopolysiloxane has surface tension of pref. 20-23 dyn/cm. Organopolysiloxane itself may have sensitive to light, or mixt. of silicone resin and light sensitive substance may be used for making protective layer. Thickness of protective layer is 1-5 mu m. Light sensitive organopolysiloxane is e.g. organopolysiloxane having siloxane unit to which maleimido, acryloxy, amido etc. is attached. Light sensitive substance to be mixed with silicone resin is e.g. azide, o-quinonediazide, cinnamic acid etc. Wettability of material for protecting layer to silicone layer is improved without lowering resolving power of light sensitive resin contained in the protective layer.