Method of molding porous articles

Claim 1

A METHOD OF MAKING AN ARTICLE OF CLOSED-CELL GAS-EXPANDED PLASTICIZED THERMOPLASTIC RESINOUS MATERIAL COMPRISING SUBSTANTIALLY FILLING A MOLD CAVITY, FORMED BY A SECTIONAL MOLD, WITH AN EXPANDABLE RESIN MIXTURE COMPRISING A PLASTISOL OF PARTICLES OF A THERMOPLASTIC RESIN AND A PLASTICIZER THEREFOR WHICH IS CAPABLE UPON HEATING OF DISSOLVING SAID RESIN TO FORM A GEL, SAID MIXTURE ALSO CONTAINING A CHEMICAL BLOWING AGENT, HEATING SAID MIXTURE IN THE MOLD CAVITY TO EFFECT PARTIAL GENERATION OF GAS FROM SAID BLOWING AGENT AND EXPANSION OF SAID MIXTURE, ALLOWING THE PRESSURE GENERATED BY SAID GAS TO FORCE A MINOR PROPORTION OF THE EXPANDING MIXTURE TO FLOW FROM SAID MOLD CAVITY THROUGH A RELATIVELY SMALL TUBULAR CONNECTING PASSAGEWAY INTO A CLOSED AUXILIARY CAVITY ALSO FORMED BY SAID SECTIONAL MOLD UNTIL SAID AUXILIARY CAVITY IS FILLED, THEREAFTER CONTINUING THE HEATING TO COMPLETE THE DECOMPOSITION OF THE BLOWING AGENT, APPLYING EXTERNAL MOLD-CLOSING PRESSURE TO THE MOLD SECTIONS SUFFICIENT TO HOLD THE MOLD CAVITY AND THE AUXILIARY CAVITY COMPLETELY CLOSED THROUGHOUT SAID HEATING STEPS, AND, AFTER DECOMPOSITION OF THE BLOWING AGENT IS COMPLETE, COOLING AND REMOVING THE SHAPED ARTICLE FROMT HE MOLD CAVITY, AND EXPANDING IT TO FINAL SIZE BY HEATING IT OUTSIDE THE MOLD.

Claim 2

A METHOD OF MAKING AN ARTICLE OF CLOSED-CELL GAS-EXPANDED PLASTICIZED THERMOPLASTIC RESINOUS MATERIAL COMPRISING SUBSTANTIALLY FILLING A MOLD CAVITY, FORMED BY A SECTIONAL MOLD, WITH AN EXPANDABLE RESIN MIXTURE COMPRISING A PLASTISOL OF PARTICLES OF A THERMOPLASTIC RESIN AND A PLASTICIZER THEREFOR WHICH IS CAPABLE UPON HEATING OF DISSOLVING SAID RESIN TO FORM A GEL, SAID MIXTURE ALSO CONTAINING A CHEMICAL BLOWING AGENT, HEATING SAID MIXTURE IN THE MOLD CAVITY TO EFFECT PARTIAL GENERATION OF GAS FROM SAID BLOWING AGENT AND EXPANSION OF SAID MIXTURE, ALLOWING THE PRESSURE GENERATED BY SAID GAS TO FORCE A MINOR PROPORTION OF THE EXPANDING MIXTURE TO FLOW FROM SAID MOLD CAVITY THROUGH A RELATIVELY SMALL TUBULAR CONNECTING PASSAGEWAY INTO A CLOSED AUXILIARY CAVITY ALSO FORMED BY SAID SECTIONAL MOLD UNTIL SAID AUXILIARY CAVITY IS FILLED, THEREAFTER CONTINUING THE HEATING TO COMPLETE THE DECOMPOSITION OF THE BLOWING AGENT, APPLYING EXTERNAL MOLD-CLOSING PRESSURE TO THE MOLD SECTIONS SUFFICIENT TO HOLD THE MOLD CAVITY AND THE AUXILIARY CAVITY COMPLETELY CLOSED THROUGHOUT SAID HEATING STEPS, AND, AFTER DECOMPOSITION OF THE BLOWING AGENT IS COMPLETE, COOLING AND REMOVING THE SHAPED ARTICLE FROMT HE MOLD CAVITY, AND EXPANDING IT TO FINAL SIZE BY HEATING IT OUTSIDE THE MOLD.