| 摘要 |
A polyurethane elastomer is prepared by reacting at a temperature of 170 DEG to 250 DEG C. an essentially anhydrous mixture of (1) an essentially linear polymeric organic compound having terminal hydroxyl groups and a M.W. of 500 to 5000; (2) a saturated aliphatic glycol containing 2 to 12 carbon atoms; and (3) an organic diisocyanate the molar ratio of (2):(1) being in the range of 1.6:1 to 3.0:1 and the amount of diisocyanate in the mixture being in a 2 to 8% molar excess of the combined amounts of glycol and polymeric hydroxyl group containing compound. Suitable polymeric organic compounds having terminal hydroxyl groups are polyesters and polyethers. Exemplified polyesters are those prepared from a mixture of ethylene glycol, 1,4-butane diol and adipic acid, a mixture of 2,2-dimethylpropanediol, 1,6-hexanediol and adipic acid and polycaprolactone whilst the exemplified polyether is poly(tetramethylene glycol). In the case of the polyesters a small amount of a polyol such as trimethylolpropane, trimethylol ethane and pentaerythritol may be incorporated into the polyester. A similar polyol may also be incorporated into the aliphatic glycol (2). The preferred aliphatic glycols (2) are 1,4-butanediol and 1,6-hexanediol. Many diisocyanates are listed those preferred being aromatic diisocyanates especially 4,41-diphenylmethane diisocyanate. The resulting polyurethane melt may be spun to form filaments or shaped into other articles both of which may be subjected to a heat treatment at 50 DEG C. to 250 DEG C. |
