Forming mass of thermoplastic resin

Claim 1

A PROCESS OF PREPARING CLOSED-CELL, GAS-CONTAINING CELLULAR BODIES OF NATURAL AND ARTIFICIAL ELASTOMERS AND THERMOPLASTIC RESINS, COMPRISING THE STEPS OF INTRODUCING INTO AN OPEN MOLD A MASS COMPOSED OF PARTICLES OF SOLID MATERIAL SELECTED FROM THE GROUP CONSISTING OF ELASTOMERS AND THERMOPLASTIC RESINS, SAID MASS BEING LOOSELY PACKED AND HAVING A LARGE SURFACE AREA DEFINING PASSAGE THROUGH SAID MASS CAUSING THE SURFACE OF THE SAME TO BE ACCESSIBLE TO SURROUNDING ATMOSPHERE; CLOSING SAID MOLD; MECHANICALLY COMPRESSING SAID MASS SO AS TO SUBSTANTIALLY DECREASE THE VOLUME THEREOF WHILE RETAINING PASSAGE THROUGH SAID MASS; INTRODUCING A GAS WHICH IS SUBSTANTIALLY INSOLUBLE IN SAID MASS AT ATMOSPHERIC PRESSURE FROM WITHOUT SAID MOLD INTO SAID MOLD, THEREBY INCREASING THE GAS PRESSURE IN SAID MOLD AND DISTRIBUTING SAID GAS THROUGH SAID MASS AND THE ELEVATED PRESSURE CAUSING PARTIAL DISSOLUTION OF SAID GAS IN SAID SOLID MATERIAL OF SAID MASS; HEATING THE CONTENTS OF SAID MOLD WHILE STILL COMPRESSED UNTIL GELATINIZATION OF SAID MATERIAL, THEREBY FORMING A HOMOGENEOUS MASS OF SAID MATERIAL HAVING SAID GAS EVENLY DISTRIBUTED THEREIN; AND COOLING THE THUS FORMED MASS AND RELEASING THE PRESSURE THEREON, THEREBY CAUSING THE SAME TO EXPAND AND FROM A CLOSED-CELL GAS-CONTAINING CELLULAR BODY.