| 摘要 |
A monomer containing the group <FORM:1063237/C3/1> is photopolymerized in the presence of water and of a ferric salt of a benzilic acid as the sole catalyst. Specified monomers are N,N1-methylenebisacrylamide, methylolacrylamide, N-ethanolacrylamide, calcium, acrylate, acrylic acid, acrylonitrile, (meth)acrylamide, methyl methacrylate and sodium methacrylate. The ferric salt may be performed or formed in situ from a ferric salt, e.g. FeCl3, Fe2(SO4)3, FeNH4(SO4)2 or FePO4, and the acid, e.g. benzilic acid, diphenylene glycollic acid or a benzilic acid of general formula <FORM:1063237/C3/2> wherein R1, R2, R3 and R4 are in the meta or para positions and may be hydroxyl, alkyl or vinyl groups, examples being 3,31-dihydroxy, 4,41-dihydroxy, 4-vinyl, 4,41-divinyl, 3-methyl, 4-methyl, 4,41-dimethyl and 4-hydroxy benzilic acids. The polymerization is carried out in aqueous solution or in coated dry layers containing retained water, using U.V. or visible light. In the latter case, an aqueous solution of monomer, catalyst and a water-soluble carrier, e.g. gelatin, glue, casein, hydroxyethyl cellulose, polyvinyl alcohol or polyvinyl pyrrolidone is applied to a backing and the coating is dried prior to exposure to light. The pH of Me reaction mixture is 6 or below. In the examples, N,N1 - methylenebisacrylamide is photo-polymerized in an aqueous solution containing the catalyst, or alternatively the solution is coated on baryta paper or film base and dried before exposure.
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