Thin load supporting polyurethane foam and method of making same

Claim 1

IN A PROCESS FOR PRODUCING A LIGHTWEIGHT NON-CRUSTED POLYURETHANE-CONTAINING LOAD SUPPORTING ARTICLE, THE IMPROVEMENT WHICH COMPRISES APPLYING A LIQUID POLYURETHANE-FORMING COMPOSITION, WHICH IS ADAPTED TO REACT WHEN CONTACTED WITH A MEMBER OF THE GROUP CONSISTING OF WATER AND WATER VAPOR, TO A FLEXABLE BACKING MEMBER HAVING A PLURALITY OF SPACED, DEPRESSED PORTIONS, PASSING SAID BACKING MEMBER CONTAINING SAID LIQUID POLYURETHANE-FORMING COMPOSITION IN SAID DEPRESSED PORTIONS THROUGH A ZONE CONTAINING WATER VAPOR AT TEMPERATURE OF ABOUT 100* TO 200*F. TO CAUSE AN INITIAL REACTION AT THE EXPOSED SURFACE OF SAID POLYURETHANE-FORMING COMPOSITION AND PRODUCE A STREAM-PERMEABLE, NON-FOAMED, POLYURETHANE SKIN ON THE EXPOSED SURFACE OF SAID LIQUID, SAID POLYURETHANE SKIN BEING SUFFICIENT IN THICKNESS TO RETAIN GAS FORMED DURING SUBSEQUENT PRODUCTION OF POLYURETHANE SPONGE FROM THE REMAINDER OF SAID FLUID POLYURETHANE-FORMING COMPOSITION CONTAINED IN SAID DEPRESSED PORTIONS, THEN CAUSING REACTION OF AND BLOWING OF THE REMAINING POLYURETHANE-FORMING LIQUID COMPOSITION BY CONTACTING SAID COMPOSITION WITH STEAM AT A TEMPERATURE NOT IN EXCESS OF ABOUT 350*F., TO CAUSE THE PREMEATION OF WATER VAPOR THROUGH SAID GAS-RETAINING, NON-FOAMED POLYURETHANE SKIN SO AS TO FORM RESILIENT FOAMED POLYURETHANE SPONGE BETWEEN SAID NON-FOAMED POLYURETHANE SKIN AND SAID FLEXIBLE BACKING MEMBER.