| 摘要 |
1360081 Photo-polymerizable materials E I DU PONT DE NEMOURS & CO 5 Oct 1971 [5 Oct 1970] 46315/71 Heading G2C A photo-polymerizable element comprises (a) a polymeric support carrying (b) a photopolymerizable layer of an ethylenically unsaturated monomer, a photo-initiator and a polymeric binder; the layer being at least 1À27 microns thick and having an optical density of less than 0À7 and the monomer being present in excess of the absorptive capacity of the binder so that a layer of free monomer is present at the surface remote from the support. A temporary cover sheet (c) or a metal or polymeric layer (d) may be applied to layer (b), the adhesion of (b) to (a) being greater than to (c) or (d). The element, after applying layer (d), may be imagewise exposed through the support and stripped apart leaving the exposed areas on layer (d) and the unexposed areas on the support (a). The unexposed areas may either be uniformly exposed to produce a resist image or be transferred to a receptor sheet under pressure the unexposed areas being optionally powder developed before either step. The element may be uniformly heated after exposure and before stripping. Colour proofs may be produced by powder development of the unexposed areas on the support (a) followed by transfer of powder plus unexposed areas by heat and pressure to a paper sheet and repeating for another colour. Specified binders for layer (b) are vinylidene chloride copolymers, ethylene/vinyl acetate copolymers, cellulose ethers, vinyl chloride or acetate polymers or copolymers, acrylic polymers and synthetic rubbers e.g. butadiene/ acrylonitride copolymers, chlorinated isoprene or 2-chloro-beta-1, 3-diene polymers. In the examples, polymethylmethacrylate, chlorinated rubber or a mixture thereof or polyvinyl chloride are used and pentaerythritol triacrylate or trimethylolpropane triaerylate is used as the monomer, the binder: monomer ratio varying from 0À21 to 3À46 to 1. The layer (b) may contain a dye. |
