Destruction of unreacted isocyanato groups in polyurethane elastomers by exposure tosteam

Claim 1

IN A PROCESS FOR PREPARING PROCESSABLE POLYURETHANE ELASTOMERS EXHIBITING DURING AGING SUBSTANTIAL RESISTANCE TO CHANGE OF ITS TINIUS OLSEN FLOW VALUE AS MEASURED AT THE TEMPERATURE OF 212*F AND 500 POUNDS PER SQUARE INCH PRESSURE, THE STEPS COMPRISING (1) PREPARING A PROCESSABLE POLYURETHANE ELASTOMER BY (A) FORMING A REACTION MIXTURE COMPRISING 0.9 TO 2 MOLS OF AN ORGANIC POLYISOCYANATE FOR EACH MOL OF A REACTIVE HYDROGEN-CONTAINING COMPOUND HAVING A MOLECULAR WEIGHT OF ABOUT 750 TO NO GREATER THAN 10,000, (B) REACTING TOGETHER THE INGREDIENTS OF SAID MIXTURE TO FORM A REACTION PRODUCT, AND (C) SUBJECTING SAID REACTION PRODUCT TO A HEAT TREATMENT UNITL IT HAS A TINIUS OLSEN FLOW VALUE OF ABOUT 182, AND (2) SUBJECTING THE PRODUCT OF 1(C) IN SHEET FORM TO STREAM VAPOR FOR A TIME SUFFICIENT TO DESTROY ANY FREE ISOCYANATE GROUPS PRESENT, SAID REACTION PRODUCT HAVING BEEN FORMED INTO A SHEET HAVING A THICKNESS OF ABOUT .25 INCH AFTER STEP 1(B) AND PRIOR TO STEP 2; SAID REACTIVE HYDROGEN CONTAINING COMPOUND BEING SELECTED FROM THE CLASS CONSISTING OF POLYESTERS, POLYESTERAMIDES AND POLYETHER GLYCOLS.