Suitably, the diisocyanates are reacted with from about 0.01 to about 0.5 equivalents of a polyol having a molecular weightbelow about 700; beneficially, with about 0.015 to about 0.25 equivalents of polyols having a molecular weight from about 130 to about 300 in the case of such polyols as propylene glycol, butylene glycol, and the like or with a polypropylene ether glycolhaving a molecular weig