GB533497A - Improvements in and relating to synthetic resins and to articles made therefrom - Google Patents

Abstract

533,497. Vinyl polymerization products. NORTON GRINDING WHEEL CO., Ltd. May 8, 1939, No. 13666. Convention date, Jan. 30. [A Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 8, 1939.] [Class 2 (iii)] Synthetic resins suitable for optical purposes and abrasives, are prepared by polymerizing, by known methods, a mixture of methyl methacrylate with methacrylic and/or acrylic anhydrides. A copolymer of methyl methacrylate and 5 per cent. of methacrylic anhydride is infusible and insoluble; a resin produced with 10 per cent. of methacrylic anhydride is suitable for shaping by grinding and polishing operations to produce an optical element. An abrasive article, e.g. a grinding wheel, may be produced from a mixture of abrasive grains with methyl methacrylate and 20 per cent. of methacrylic anhydride polymerized by heat in a suitable mould. Optical properties of the resin, e.g. refractive index, may be modified by the addition of a further polymerizable substance to the monomeric mixture e.g. nitroethylene, triphenylmethyl acrylate or methacrylate, o, m, or p-nitro-styrene, vinyl chloride, vinyl acetate or furyl vinyl ketone, or of a non-polymerizable substance having a high index of refraction, e.g. triphenylbenzene.