| 摘要 |
1,174,984. Foamed, oriented thermoplastic film. PHILLIPS PETROLEUM CO. 21 April, 1967 [22 April, 1966], No. 18563/67. Headings C3C and C3P. Foamed and oriented thermoplastic film is made by extruding a mixture of a molten thermoplastic polymer and a blowing agent to give a foamed film which is passed through a quenching zone to cool the film below the polymer melting point, reheating the film whilst supported on a uniform smooth heating surface and stretching the film whilst hot to effect orientation. The polymer is preferably a 1- olefin having 2-1 C atoms and a m.pt. of 225- 350‹ F., e.g. polypropylene. The blowing agent may be a volatile hydrocarbon such as butane, a decomposable solid such as azodicarbonamide or a compressed inert gas such as nitrogen or helium. The film is preferably quenched in water, heated on one or more moving rollers and stretched to 3 to 10 times its original length. The example describes the preparation of a film from polypropylene containing polyisobutylene as a dispersing agent, a red organic pigment and azodicarbonamide as blowing agent. |
