| 摘要 |
Transparent mouldable thermoplastic compositions comprise 30 to 70 parts by weight of a comolymer having a refractive index between nD25 1,5350 and nD25 1,5750 and containing in chemically combined form from 5 to 62 % by weight of a methacrylic ester of an alkanol containing 1 to 6 carbon atoms, and from 95 to 38% of at least one of styrene, vinyl xylene, ethyl vinyl benzene, vinyl toluene and a -methyl styrene, and intimately blended therewith from 70 to 30 parts by weight of a copolymer of from 25 to 70% by weight of styrene and from 75 to 30% of butadiene, which copolymer has a refractive index between nD25 1,5350 and nD25 1,5750 and within 0,004 of that of the copolymer of alkenyl aromatic hydrocarbon and methacrylic acid ester. The compositions may be prepared by heat-plastifying and mechanically working the copolymers, optionally together with lubricants, e.g. butyl stearate, white mineral oil, soya bean oil and ethyl laurate, fillers, dyes, pigments, plasticisers and stabilisers, e.g. 2, 6-di-tertiary butyl-4-methylphenol. The methacrylic ester may be methyl, ethyl, butyl or hexyl methacrylate, and examples describe the compounding of copolymers of methyl methacrylate, meta-vinyl-toluene and para-vinyl toluene, and methyl methacrylate, styrene and a -methyl styrene. |
