Method for the production of closed cell rubber

Claim 1

THE METHOD OF PRODUCING ELONGATED STRIPS OF CLOSED CELL, CELLULAR, GAS EXPANDED RUBBER FROM A RUBBER COMPOUND HAVING DISPERSED THEREIN A SUBSTANCE WHICH, ON THE APPLICATION OF HEAT, GENERATES A GAS, WHICH COMPRISES THE STEPS OF WINDING A STRIP OF RUBBER COMPOUND ONTO AN ELONGATED CYLINDRICAL MANDREL HAVING AT ITS OPPOSITE ENDS SLEEVES SLIDABLE CONCENTRICALLY THEREON, SAID STRIP OF RUBBER COMPOUND BEING WOUND ON SAID MANDREL SO THAT ITS OPPOSITE ENDS ARE IN CONTACT WITH SAID SLEEVES THEREBY FORMING A SHEET LIKE LAYER ON SAID MANDREL COVERING SAID MANDREL BETWEEN SAID SLEEVES, POSITIONING SAID MANDREL WITH SAID RUBBER COMPOUND WOUND THEREON IN A CYLINDRICAL MOLD MEANS TO ENCOMPASS SAID MANDREL, SAID RUBBER COMPOUND AND AT LEAST A PORTION OF THE SLEEVE AT EACH END OF THE MANDREL TO THEREBY FORM AN ANNULAR MOLD CAVITY CLOSELY CONFINING SAID SHEET LIKE LAYER OF RUBBER COMPOUND, HEATING SAID MANDREL AND SAID CONFINED RUBBER COMPOUND TO A TEMPERATURE SUFFICIENT TO GENERATE SAID GAS AND CURE SAID RUBBER COMPOUND, SAID HEAT THERMALLY EXPANDING SAID CONFINED RUBBER COMPOUND TO FORCE SAID PAIR OF SLEEVES TO SLIDE AXIALLY OUTWARD ALONG SAID MANDREL, MEANS AT THE ENDS OF SAID MANDREL FOR STOPPING THE AXIAL MOVEMENT OF SAID SLEEVES TO RESTRAIN SAID SLEEVES AGAINST FURTHER OUTWARD AXIAL MOVEMENT AFTER SAID RUBBER COMPOUND IS THERMALLY EXPANDED, MAINTAINING SAID TEMPERATURE FOR A SUFFICIENT PERIOD TO GENERATE SAID GAS AND TO CURE SAID RUBBER COMPOUND WHILE RESTRAINING FURTHER EXPANSION OF SAID CONFINED SHEET LIKE LAYER DUE TO THE EVOLUTION OF SAID GAS IN SAID STRIP OF RUBBER COMPOUND, THEREAFTER COOLING THE CURED STRIP OF RUBBER, AND REMOVING SAID CYLINDRICAL MOLD MEANS ENCOMPASSING SAID MANDREL TO PERMIT THE RESULTING STRIP OF CURED, CLOSED CELL, CELLULAR RUBBER TO EXPAND UNDER THE PRESSURE OF GAS TRAPPED THEREIN.

Claim 2

THE METHOD OF PRODUCING ELONGATED STRIPS OF CLOSED CELL, CELLULAR, GAS EXPANDED RUBBER FROM A RUBBER COMPOUND HAVING DISPERSED THEREIN A SUBSTANCE WHICH, ON THE APPLICATION OF HEAT, GENERATES A GAS, WHICH COMPRISES THE STEPS OF WINDING A STRIP OF RUBBER COMPOUND ONTO AN ELONGATED CYLINDRICAL MANDREL HAVING AT ITS OPPOSITE ENDS SLEEVES SLIDABLE CONCENTRICALLY THEREON, SAID STRIP OF RUBBER COMPOUND BEING WOUND ON SAID MANDREL SO THAT ITS OPPOSITE ENDS ARE IN CONTACT WITH SAID SLEEVES THEREBY FORMING A SHEET LIKE LAYER ON SAID MANDREL COVERING SAID MANDREL BETWEEN SAID SLEEVES, POSITIONING SAID MANDREL WITH SAID RUBBER COMPOUND WOUND THEREON IN A CYLINDRICAL MOLD MEANS TO ENCOMPASS SAID MANDREL, SAID RUBBER COMPOUND AND AT LEAST A PORTION OF THE SLEEVE AT EACH END OF THE MANDREL TO THEREBY FORM AN ANNULAR MOLD CAVITY CLOSELY CONFINING SAID SHEET LIKE LAYER OF RUBBER COMPOUND, HEATING SAID MANDREL AND SAID CONFINED RUBBER COMPOUND TO A TEMPERATURE SUFFICIENT TO GENERATE SAID GAS AND CURE SAID RUBBER COMPOUND, SAID HEAT THERMALLY EXPANDING SAID CONFINED RUBBER COMPOUND TO FORCE SAID PAIR OF SLEEVES TO SLIDE AXIALLY OUTWARD ALONG SAID MANDREL, MEANS AT THE ENDS OF SAID MANDREL FOR STOPPING THE AXIAL MOVEMENT OF SAID SLEEVES TO RESTRAIN SAID SLEEVES AGAINST FURTHER OUTWARD AXIAL MOVEMENT AFTER SAID RUBBER COMPOUND IS THERMALLY EXPANDED, MAINTAINING SAID TEMPERATURE FOR A SUFFICIENT PERIOD TO GENERATE SAID GAS AND TO CURE SAID RUBBER COMPOUND WHILE RESTRAINING FURTHER EXPANSION OF SAID CONFINED SHEET LIKE LAYER DUE TO THE EVOLUTION OF SAID GAS IN SAID STRIP OF RUBBER COMPOUND, THEREAFTER COOLING THE CURED STRIP OF RUBBER, AND REMOVING SAID CYLINDRICAL MOLD MEANS ENCOMPASSING SAID MANDREL TO PERMIT THE RESULTING STRIP OF CURED, CLOSED CELL, CELLULAR RUBBER TO EXPAND UNDER THE PRESSURE OF GAS TRAPPED THEREIN.