GB536722A - Improvements relating to synthetic resins - Google Patents

Abstract

536,722. Vinyl polymerization products ; unsaturated acrylates. NORTON GRINDING WHEEL CO., Ltd. Aug. 22, 1939, No. 24140. Convention date, Aug. 27, 1938. [Class 2 (iii)] A resin, suitable for use in the manufacture of optical elements or abrasive bodies, is prepared by co-polymerizing vinyl methacrylate with methyl methacrylate, styrene or vinyl acetate. A further polymerizable substance adapted to modify the refractive index and/or dispersion value of the co-polymer may be present, e.g. acrylic or methacrylic acid esters of the hydroxy-quinolines, the nitrophenols, the chlorophenols and triphenylmethyl-carbinol, styrene, nitroethylene and o, m, and p-nitrostyrene. In examples, (1) vinyl methacrylate and methyl methacrylate are heated in the presence of a polymerization catalyst such as benzoyl peroxide ; (2) a grinding wheel is prepared by pouring a mixture of vinyl methacrylate, methyl methacrylate and benzoyl peroxide upon abrasive grain, e.g. aluminium oxide or silicon carbide, in a mould which is then heated to effect the polymerization ; and (3) a grinding wheel is prepared by mixing a finely divided co-polymer of vinyl methacrylate and methyl methacrylate, obtained either by grinding the solid copolymer or by polymerizing the monomers in solution in carbon tetrachloride in which the co-polymer is insoluble, with abrasive grain in a mould and submitting the mixture to heat and pressure. In making lenses, the co-polymer is formed in a two-part cylindrical mould, the resulting rod being cut into discs and ground to shape. Specification 512,806 is referred to. According to the Specification as open to inspection under Sect. 91, vinyl methacrylate is co-polymerized with any compatible substances containing a CH 2 = group. Vinyl acrylate, vinyl methacrylate and homologues thereof are prepared by the addition of acetylene or a substituted acetylene, e.g. allylene, to acrylic or methacrylic acid using a mercuric sulphate catalyst. Vinyl methacrylate may be alternatively prepared by the addition of methacryl chloride to acetaldehyde and dehydrohalogenation of the product, or by esterifying ethylene chlorohydrin with methacryl chloride and dehydrohalogenating the chloroester thus formed. This subjectmatter does not appear in the Specification as accepted.