| 摘要 |
1283563 Polyurethanes CIBAGEIGYAG 15 Dec 1969 [16 Dec 1968] 61096/69 Heading C3R Cross-linked crystalline polyurethanes are prepared by reacting (a) a slightly branched hydroxyl terminated polyester having an average molecular weight of 1200 to 10,000 and which consists of 98 to 90 mol per cent of structural elements in ester relationship of the formulµ and (b) a diisocyanate, in amount such that 0À9 to 1À1 equivalents of isocyanate groups are employed per 1 equivalent of hydroxyl group. The polyester is formed from succinic acid, 1,4- butane diol and a polyfunctional starting molecule which is suitably a trifunctional polyalcohol or polycarboxylic acid. Aliphatic, cycloaliphatic or araliphatic diisocyanates are preferably used as the diisocyanate (b), but aromatic diisocyanates may also be used. A polyhydroxyl compound (c) different to (a) may be used as an additional cross-linking agent, similarly a polyisocyanate (d) containing at least 3 isocyanate groups may be added as an additional crosslinking agent, provided that 1 equivalent of the total amount of hydroxyl or isocyanate groups respectively contained in the reaction mixture is composed of 0À95 to 0À5 equivalents of OH groups of (a) or of NCO groups of (b) respectively and of 0À05 to 0À5 equivalents of OH groups of (c) or of NCO groups of (d) respectively. In a typical example a polyester derived from succinic anhydride, 1,4-butane diol and 1,1,1-trimethylolpropane were mixed with 3-hydroxymethyl-2,4- hydroxypentane and isophorone diisocyanate to form a moulded polyurethane. Uses.-As resins for dipping, casting, laminating, impregnating, coating, sealing, potting, insulating and as adhesives. |
