| 摘要 |
1,216,604. Polyurethanes. AMELIOTEX Inc. 16 Feb., 1968 [17 Feb., 1967; 22 Jan., 1968], No. 7680/68. Heading C3R. Solutions of substantially linear polyurethanes are prepared by reacting in a solvent (a) a prepolymer derived from a substantially linear glycol of M.W. 500 to 5000 and a mixture of at least two diisocyanates comprising a major amount, on a mole basis, of a first diisocyanate having no substituents alpha to the isocyanate groups and a minor amount, on a mole basis, of a second diisocyanate having at least one substituent group alpha to an isocyanate group, the molar ratio of total diisocyanate to glycol being 1À5-2À5 to 1, and (b) an aliphatic diprimary amine. The mixture of diisocyanate preferably contains 75 to 98 mole per cent of the first diisocyanate and 25 to 2 mole per cent of the second diisocyanate. The linear glycol is suitably a polyester, polyether or polyester/ether glycol. Preferably, the first diisocyanate is diphenylmethane - 4,4<SP>1 </SP>- diisocyanate and the second diisocyanate is tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate or mixtures thereof and the solvent is dimethylformamide. Ethylene diamine is the preferred diprimary amine. A chain terminating agent may be added to the reaction solution. In a typical example, a polyester prepared from a mixture of ethylene glycol and propylene glycol and adipic acid was mixed with a mixture of 4,41-diphenylmethane diisocyanate and an 80/20 mixture of 2,4- tolylene diisocyanate and 2,6-tolylene diisocyanate to form a prepolymer which was diluted with dimethylformamide and reacted with methylimino-bis-propylamine and subsequently with ethylene diamine and diethanolamine. Filaments may be spun from the polyurethanecontaining solutions. |
