| 摘要 |
1,221,741. Polyurethanes. FARBENFABRIKEN BAYER A.G. 24 Jan., 1969 [17 Feb., 1968], No. 4064/69. Headings C3C and C3R. Elastic or semi-elastic polyurethane shaped structures which have a compact i.e. substantially non-cellular surface, are prepared by foaming in a mould, in the absence of a surfactant, a foamable reaction mixture comprising a polyisocyanate, a low boiling organic blowing agent, and a mixture of at least two compounds which contain reactive hydrogen atoms and which differ in their reactivity towards isocyanates, at least one of which compounds is a polyalkylene glycol ether having a M.W. of 500 to 10,000, heat being supplied to the mould, either externally or from reaction heat. In an example, a polyalkylene glycol ether prepared by adding propylene oxide and ethylene oxide to trimethylolpropane, butane - 1,4 - diol, trichloromonofluoromethane and triethylene diamine are mixed together and reacted with diphenylmethane - 4,4<SP>1</SP> - diisocyanate which has undergone partial self-condensation with formation of carbodiimide groups to form a foam. |
