| 摘要 |
1,167,038. Microporous filaments. IMPERIAL CHEMICAL INDUSTRIES Ltd. 28 July, 1967 [10 Aug., 1966], No. 35789/66. Headings C3C and C3P. In a process for producing fine microporous filaments by melt extruding synthetic thermoplastic polymers, the polymer is melted under pressure and the pressure in the melt is raised immediately to a pressure of at least 1000 p.s.i.g. in the presence of a blowing agent, the pressure being maintained at or above 1000 p.s.i.g. until the molten polymer is extruded. The blowing agent may be a normally solid or liquid substance which yields gaseous products or becomes gaseous at elevated temperatures, or a normally gaseous substance. The extruded filaments may be gas-cooled, and may be stretched to up to 4 times their original length. Examples describe the preparation of filament from compositions of polypropylene, an azodicarbonamide and sodium stearate.
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