Manufacture of thin sheet foam

Claim 1

THE METHOD OF CASTING THIN, UNIFORM SHEETS OF CELLULAR POLYURETHANE RESIN COMPRISING THE STEPS OF FORMING ON A CASTING SUFACE A LAYER OF AN INCOMPLETE MIXTURE OF (1) A REACTION PRODUCT OF AN ORGANIC COMPOUND HAVING A PLURALITY OF ACTIVE HYDROGEN GROUPS AND AN EXCESS OVER THE AMOUNT REQUIRED TO REACT WITH ALL OF SAID ACTIVE HYDROGEN GROUPS OF AN ORGANIC COMPOUND HAVING A PLURALITY OF GROUPS OF THE FORMULA -NCO, (2) WATER, AND (3) CATALYST FOR THE REACTION BETWEEN WATER AND SAID REACTION PRODUCT, PROVIDING A DELAY PERIOD OF A LENGTH TO PERMIT PARTIAL REACTION OF SAID REACTION PRODUCT AND WATER TO INCREASE THE VISCOSITY OF THE INCOMPLETE MIXTURE WITHOUT PERMITTING SUBSTANTIAL EVOLUTION OF GAS, PASSING THE INCOMPLETE MIXTURE OF MATERIALS ON SAID CASTING SURFACE THROUGH A PATH OF DIMINISHING CROSS SECTION FORMING FROM SAID MATERIALS A ROLLING BANK IN SAID PATH IN WHICH THE MATERIALS ARE INTIMATELY MIXED AND FROM WHICH PORTIONS ARE SPREAD ON SAID CASTING SURFACE AS A LAYER OF UNIFORM THICKNESS, CONVERING THE MATERIALS ON SAID CASTING SURFACE WITH A LIGHT, FLEXIBLE, SUBSTANTIALLY IMPERVIOUS COVER SHEET PRIOR TO SUBSTANTIAL DEVELOPMENT OF GAS AND RAISING THE TEMPERATURE OF SAID LAYER TO COMPLETE REACTION BETWEEN SAID REACTION PRODUCT AND WATER TO DEVELOP GAS TO EXPAND THE LAYER AND TO CAUSE IT TO BECOME FIRM AS A CELLULAR POLYURETHANE RESIN LAYER, SAID COVER SHEET SUBSTANTIALLY PREVENTING LOSS OF GASEOUS AND VOLATILE MATERIALS AND RAPTURE OF GAS CELLS AT THE SURFACE OF SAID LAYER.

Claim 2

THE METHOD OF CASTING THIN, UNIFORM SHEETS OF CELLULAR POLYURETHANE RESIN COMPRISING THE STEPS OF FORMING ON A CASTING SUFACE A LAYER OF AN INCOMPLETE MIXTURE OF (1) A REACTION PRODUCT OF AN ORGANIC COMPOUND HAVING A PLURALITY OF ACTIVE HYDROGEN GROUPS AND AN EXCESS OVER THE AMOUNT REQUIRED TO REACT WITH ALL OF SAID ACTIVE HYDROGEN GROUPS OF AN ORGANIC COMPOUND HAVING A PLURALITY OF GROUPS OF THE FORMULA -NCO, (2) WATER, AND (3) CATALYST FOR THE REACTION BETWEEN WATER AND SAID REACTION PRODUCT, PROVIDING A DELAY PERIOD OF A LENGTH TO PERMIT PARTIAL REACTION OF SAID REACTION PRODUCT AND WATER TO INCREASE THE VISCOSITY OF THE INCOMPLETE MIXTURE WITHOUT PERMITTING SUBSTANTIAL EVOLUTION OF GAS, PASSING THE INCOMPLETE MIXTURE OF MATERIALS ON SAID CASTING SURFACE THROUGH A PATH OF DIMINISHING CROSS SECTION FORMING FROM SAID MATERIALS A ROLLING BANK IN SAID PATH IN WHICH THE MATERIALS ARE INTIMATELY MIXED AND FROM WHICH PORTIONS ARE SPREAD ON SAID CASTING SURFACE AS A LAYER OF UNIFORM THICKNESS, CONVERING THE MATERIALS ON SAID CASTING SURFACE WITH A LIGHT, FLEXIBLE, SUBSTANTIALLY IMPERVIOUS COVER SHEET PRIOR TO SUBSTANTIAL DEVELOPMENT OF GAS AND RAISING THE TEMPERATURE OF SAID LAYER TO COMPLETE REACTION BETWEEN SAID REACTION PRODUCT AND WATER TO DEVELOP GAS TO EXPAND THE LAYER AND TO CAUSE IT TO BECOME FIRM AS A CELLULAR POLYURETHANE RESIN LAYER, SAID COVER SHEET SUBSTANTIALLY PREVENTING LOSS OF GASEOUS AND VOLATILE MATERIALS AND RAPTURE OF GAS CELLS AT THE SURFACE OF SAID LAYER.