| 摘要 |
1,217,352. Moulding plastic substances. E. I. DU PONT DE NEMOURS & CO. 20 June, 1968 [20 June, 1967], No. 29565/68. Heading B5A. [Also in Division C3] A foamed polylactam article is made by adding a blowing agent under pressure to a molten lactam which is then polymerized in the presence of lactam-base salt and polymerization promoter in a mould cavity under a pressure at least sufficiently to maintain the blowing agent in the resulting polylactam, and after the lactam is completely polymerized an exit post communicating with the mould is opened whereby pressure on the polylactam is reduced and the polylactam is ejected out of the mould to form a solid foamed moulded article. The lactam may be caprolactam, caprylolactam and/or laurolactam. The blowing agent may propane, butane and/or pentane or propylene, cyclopropane, argon or nitrogen. The drawing shows the production of a foamed polylactam from #-caprolactam, promoter e.g. poly-{ 2,2 - propane bis-(4-phenylene) carbonate }, anionic catalyst, i.e. lactam-base salt e.g. made from potassium stearate and sodium hydride and rafactant which also acts as mould release agent. The moulded foamed polycaprolactam may be in the form of a hallow cylinder which may be cut and flattened in a press to form a
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