Segmented polyurethane/ureas useful in the production of spandex with improved heat set are produced by chain extending an isocyanate-terminated prepolymer with a diamine chain extender that includes: (1) greater than 25 to 75 equivalent percent of an asymmetric aliphatic and/or cycloaliphatic diamine and (2) a linear diamine such as ethylene diamine in the presence of a solvent. The isocyanate-terminated prepolymer having an isocyanate group content of from about 2.25 to about 4 is produced by reacting a stoichiometric excess of an isocyanate with an isocyanate-reactive component that includes: (1) from about 25 to about 75 equivalent percent of a polyoxypropylene diol having a molecular weight in excess of 1500 Da and an average unsaturation level of less than about 0.03 meq/g and (2) from about 25 to about 75 equivalent percent of a polytetramethylene ether glycol having a molecular weight of at least 600 Da.
用于生产热固性更好的
氨纶的分段聚
氨酯/
氨纶是通过用二胺扩链剂对
异氰酸酯封端预聚物进行扩链而生产的,扩链剂包括:(1) 25%至 75%的不对称脂肪族和/或环脂肪族二胺;(2) 线性二胺,如
乙二胺:(1) 超过 25% 至 75% 的不对称脂肪族和/或环脂族二元胺;(2) 在溶剂存在下的线性二元胺,如
乙二胺。
异氰酸酯封端预聚物具有约 2.25 至约 4 的
异氰酸酯基含量,是通过使按
化学计量过量的
异氰酸酯与
异氰酸酯反应组分反应制得的,该反应组分包括:(1) 约 25 至约 4 的
异氰酸酯基含量;(2) 约 25 至约 4 的
异氰酸酯基含量;(3) 约 25 至约 4 的
异氰酸酯基含量:(1)分子量超过 1500 Da 且平均不饱和度低于约 0.03 meq/g 的聚氧
丙烯二元醇的约 25%至约 75%的当量;(2)分子量至少为 600 Da 的
聚四亚甲基醚二醇的约 25%至约 75%的当量。