| 摘要 |
Polyurethanes suitable for melt extrusion comprise the reaction product of a linear polyester of not over 1,400 average molecular weight with at least one di-isocyanate in proportions less than 0.7 or more than 1 mol. of di-isocyanate per mol. of polyester, and of additional di-isocyanate and a dihydric chain extender to give a polymer having a degree of polymerization within the fibre forming range and not exceeding that corresponding to a melt stick temperature of 249 DEG C. Di-isocyanates specified are methylene-bis (4-phenyl isocyanate), toluene di-isocyanate, tetramethylene di-isocyanate, hexamethylene di-isocyanate and meta-xylylene di-isocyanate. The polyesters may be the ethylene and/or propylene esters of adipic, sebacic and/or terephthalic acids. Di-hydric chain extenders specified are 1,4-butanediol and 1,5-pentanediol. |
