| 摘要 |
1,238,941. Foamable lactam compositions. FARBENFABRIKEN BAYER A.G. 17 Sept., 1968 [20 Oct., 1967], No. 44141/68. Headings C3C and C3R. Lactam compositions capable of being converted to polyamide foams are made by heating a lactam with a catalyst for lactam polymerization which is insoluble in the lactam at the melting temperature of the lactam, at such a temperature that the catalyst dissolves without the lactam polymerizing, then precipitating the catalyst by cooling with stirring to a temperature up to 15‹ C. above the melting point of the lactam, adding activators for lactam polymerization, blowing agents and pore regulators to the lactam at this temperature and then flaking off the melt thus obtained over a cooling roller. The lactam may be caprolactam, and the catalyst may be an alkali metal or alkaline earth metal formate. An isocyanate or adduct thereof, e.g. hexamethylene diisocyanate may serve as both an activator and a blowing agent. The composition may contain silica gel or tale as crystallization nuclei and a polysiloxane-oxyalkylene block copolymer as pore regular. A foam may be made by heating the composition. |
