| 摘要 |
1287803 Polyurethanes CIBA-GEIGY AG 8 Dec 1969 [9 Dec 1968] 59897/69 Heading C3R [Also in Division C2] Cross-linked, crystalline polyurethanes are prepared by reacting (a) a linear polyester consisting essentially of elements of the formula in ester-relationship to one another each of which elements must occur in the molecule at least four times and at most 30 times on average, (b) a cross-linking agent which is a polyhydroxy compound containing at least 3 alcoholic hydroxyl groups and (c) a diisocyanate, in amount such that the overall NCO/OH ratio is 0À9 to 1À1 : 1, the equivalent ratio of components (a) and (b) being chosen so that 1 equivalent of the total amount of the total amount of OH groups is composed of 0À95 to 0À5 equivalents of OH groups from the polyester (a) and 0À05 to 0À5 equivalents of OH groups from the polyhydroxyl compound (b). The polyester is prepared by reacting succinic acid or its anhydride with 1,4- butane diol. Preferred cross-linking agents (b) are aliphatic or cycloaliphatic polyalcohols having 3 to 6 OH groups or their reaction products with a monoepoxide. Particularly suitable cross-linking agents are glycerine or hexanetriols or their reaction products with ethylene oxide, propylene oxide or styrene oxide. Aliphatic, cycloaliphatic or araliphatic diisocyanates are preferred but aromatic diisocyanates may also be used. Conventional catalysts may be added to the reaction mixture. In a typical example, a polyester from succinic acid and 1,4- butane diol having an OH equivalent weight of 935 is mixed with 3-hydroxymethyl-2,4-dihydroxypentane and the mixture warmed with isophorone diisocyanate to form a moulded product. Uses.-As resins for dipping, casting, laminating, impregnating, coating, sealing, potting, insulating and as adhesives. |
