| 摘要 |
1,162,517. Polyurethane foams. DUNLOP CO. Ltd. 21 Oct., 1966 [12 Nov., 1965], No. 48024/65. Headings C3C and C3R. A cold-curing process for the manufacture of polyurethane foam comprises reacting in a mould without the application of heat a polymeric polyol which is an ethylene oxide tipped polyoxypropylene and a polyisocyanate having 2, 3 or 4 benzene rings each linked by a methylene group and each carrying at least one isocyanate group in the presence of a blowing agent. The polyisocyanate is preferably a diphenylmethane diisocyanate or a polyphenylene polymethylene isocyanate. Suitable polyols are block copolymers of propylene oxide and ethylene oxide or a glycerol-centred oxyethylene tipped polyoxypropylene triol. A catalyst such as a tertiary amine or an organic tin compound or mixtures thereof and a surface-active agent such as a polysiloxaneoxyalkylene block copolymer may also be included in the reaction mixture. Water and/or fluorinated hydrocarbons may be used as blowing agents. |
