| 摘要 |
1,263,607. Polyurethanes. FARBENFABRIKEN BAYER A.G. 10 July, 1969 [15 July, 1968], No. 34827/69. Headings C3G, C3P and C3R. Polyurethanes are prepared by reacting (a) polyisocyanate with (b) modified aliphatic polycarbonates which have been prepared by polymerization of one or more compounds which contain one or more polymerizable C=C bonds in the presence of one or more aliphatic polycarbonates which contain at least two OH groups and have a M.W. of 800 to 3000, and depending on the conditions the polymers which have been prepared in situ are suspended in the polycarbonates, in some cases as homopolymers or may be partly or completely dissolved in the polycarbonate or may be present partly or completely as graft polymers. The modified polycarbonate is suitably prepared by dissolving the polymerizable unsaturated compound in the polycarbonate, followed by polymerization with the addition of radical forming initiators or the monomer and the activator may be slowly added to the polycarbonate or the activator may be heated with the polycarbonate and the monomer added subsequently. Acrylonitrile and methyl-, ethyl- and butyl-acrylate are suitable monomers whilst the preferred polycarbonate is hexane - 1,6 - diol polycarbonate. Chain lengthening and/or cross-linking agents, e.g. glycols and diamines, may be included in the reaction mixture. In a typical example diphenylmethane-4,4'-diisocyanate is reacted with a polyhydroxy compound prepared by polymerizing hexane-1,6-diol polycarbonate and acrylonitrile in situ with azodiisobutyronitrile and 1,4-butane diol is added to the melt to complete the reaction. |
