| 摘要 |
Thermoplastic processible elastic polyurethanes are produced by a process wherein a water-free mixture of a polyester or polyether having a linear structure and free terminal hydroxyl groups and a molecular weight of at least 800, and a low molecular weight aliphatic or cycloaliphatic glycol having a molecular weight below 500, the molar ratio of glycol to polyester or polyether being in the range 0.1:1 to 3.0:1 is reacted with a diisocyanate at 80 DEG to 150 DEG C., the diisocyanate being used in excess over the amount necessary to react with all the hydronyl groups. The polyester may be prepared from a mixture of one or more aliphatic acids and one or more glycols, e.g. the polyester obtained from adipic acid and ethylene glycol or butylene glycol. The preferred low molecular weight glycols are 1,4-butanediol and 1,4-butenediol. The diisocyanate may be aliphatic, cycloaliphatic or monocyclic aromatic, specified are: 4,41-diphenylmethane diisocyanate and bis-toluylene and 1,6-hexamethylene diisocyanates. |
