Process of expanding polymers of unsaturated esters of tertiary butyl alcohol and foamable product obtained therefrom

Claim 1

A PROCESS FOR THE PRODUCTION OF POROUS PLASTICS WHICH COMPRISES: HEATING A POLYMER OF A COMPOUND HAVING THE GENERAL FORMULA CH2=CH-CO2(CH3)3, IN WHICH R IS A MEMBER SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND A METHYL GROUP TO A TEMPERATURE OF FROM ABOUT 125*C. TO ABOUT 190*C. UNDER A PRESSURE SUFFICIENT TO PREVENT SAID POLYMER EXPANDING, WHEREBY SAID POLYMER IS DECOMPOSED AND ISOBUTYLENE IS SPLIT OFF, AND WHEREBY SAID ISOBUTYLENE IS HOMOGENEOUSLY DISTRIBUTED THROUGHOUT SAID POLYMER; COOLING SAID POLYMER TO A TEMPERATURE BELOW ITS SOFTENING POINT WHILE MAINTAINING A PRESSURE SUFFICIENT TO PREVENT SAID POLYMER FROM EXPANDING, AND THEREBY OBTAINING AN EXPANDABLE POLYMER CONTAINING ISOBUTYLENE; AND THEREAFTER HEATING SAID POLYMER TO A TEMPERATURE FROM ITS SOFTENING POINT UP TO ABOUT 50* ABOVE ITS SOFTENING POINT AT A TEMPERATURE OF FROM 1 TO 4 ATMOSPHERES, WHEREBY THE ISOBUTYLENE IS RELEASED AND A POROUS PRODUCT IS OBTAINED.