| 摘要 |
1,241,876. Polystyrene films. SUMITOMO CHEMICAL CO. Ltd. 29 Jan., 1969 [29 Jan., 1968], No. 4937/69. Heading B5B. [Also in Division C3] A film of styrene polymer is made by stretching a film of thickness 0À01-3 mm. to cause molecular orientation therein until the percentage thermal shrinkage (determined by dipping the sheet into glycerine for 5 seconds at a temperature above the softening point of the polymer) is 5-80%, contacting the surface of the stretched film with a mixture of 20-80% by vol. at least one solvent for the polymer and 80-20% of at least one non-solvent for the polymer, and then drying the film to remove the solvent mixture. The polymer may be polystyrene optionally with polybutadiene and/or a rubbery styrene-butadiene copolymer, or a copolymer of acrylonitrile, butadiene and/or styrene or of methyl methacrylate, butadiene and styrene. The solvent may be an aromatic hydrocarbon, ketone, ether, ester or halogenated hydrocarbon and the non-solvent may be an alcohol. |
