Microporous vinyl chloride resin and method of making same

Claim 1

A METHOD OF MAKING A BATTERY PLATE SEPARATOR COMPRISING THE STEPS OF BLENDING PARTICULATE VINYL CHLORIDE RESIN WITH HYDROUS SILICA GEL CONTAINING 55 TO 80% WATER, THEREAFTER BLENDING CYCLOHEXANONE WITH THE RESULTING MIXTURE TO FORM A DOUGH-LIKE MIXTURE, EXTRUDING THE DOUGHLIKE MIXTURE INTO A FORM HAVING THE CONTOUR OF A BATTERY PLATE SEPARATOR, EXPOSING THE SEPARATOR TO A SATURATED STREAM TO REMOVE THE CYCLOHEXANONE THEREFROM WITHOUT REMOVING WATER FROM THE SILICA GEL, THEREBY FIXING THE MASS IN THE SAID DESIRED FORM WHILE THE SAID WATER IS STILL PRESENT IN THE GEL, AND SUBSEQUENTLY DEHYDRATING THE SILICA GEL BY SUCH A LENGTH OF TIME AND TEMPERATURE AS TO CAUSE THE GEL TO SHRINK WITHIN SAID MASS AND TO PROVIDE MICROPOROUS VOIDS WITHIN THE MASS, SAID MASS HAVING A RESULTING POROSITY OF AT LEAST 65%.