Polyurethane prepolymers cured with butene or butyne diol

Claim 1

A PROCESS FOR THE PREPARATION OF A POLYURETHANE WHICH COMPRISES: (A) REACTING AN ORGANIC POLYISOCYANATE SELECTED FROM THE GROUP CONSISTING OF 4,4''-DIPHENYL METHANE DIISOCYANATE AND 1,5-NAPHTHYLENE DIISOCYANATE WITH AN ORGANIC COMPOUND HAVING A MOLECULAR WEIGHT OF AT LEAST ABOUT 800 AND HAVING AT LEAST TWO REACTIVE HYDROGEN ATOMS WHICH ARE REACTIVE WITH -NCO GROUPS TO FORM A POLYURETHANE, OBTAINING THEREBY A POLYURETHANE-PREPOLYMER COMPOSITION, SAID ORGANIC POLYISOCYANATE BEING PRESENT IN AN AMOUNT OF FROM ABOUT 300% TO ABOUT 700% EXCESS -NCO GROUPS OVER THAT AMOUNT REQUIRED TO REACT ONE -NCO GROUP WITH EACH ACTIVE HYDROGEN ATOM OF SAID ORGANIC COMPOUND, SAID ORGANIC COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF POLYESTERS, POLY(ALKYLENE ETHER)GLYCOLS AND POLY(ALKYLENE ETHER THIOETHER) GLYCOLS; AND (B) MIXING AND REACTING THE RESULTING POLYURETHANEPREPOLYMER COMPOSITION WITH A GLYCOL SELECTED FROM THE GROUP CONSISTING OF BUTENE DIOL AND BUTYNE DIOL, SAID GLYCOL BEING PRESENT IN AN AMOUNT LESS THAN THAT REQUIRED TO REDUCE THE -NCO CONTENT OF SAID PREPOLYMER COMPOSITION TO ZERO.