Process for preparing material used for molding microporous objects

Claim 1

THE PROCESS OF MAKING A SHEET OF FILLED BASESTOCK MOLDING MATERIAL FROM WHICH THE FILLER CAN BE SUBSTANTIALLY REMOVED AFTER A MOLDING OPERATION TO ENABLE RESILIENT MICRO-POROUS OBJECTS TO BE MAKE, SAID PROCESS CONSISTING OF MILLING ON A COLD ROLLER MILL SOLID MICRO-FINE PARTICLES OF A LEACHABLE FILLER INTO SOLID VULCANIZABLE RUBBER-LIKE MATERIAL, SAID RUBBER-LIKE MATERIAL BEING SELECTED FROM THE CLASS CONSISTING OF RUBBERY POLYMERS OF DIOLEFIN CONTAINING MATERIALS AND RUBBERY POLYSULFIDES, TO UNIFORMLY DISPERSE THE PARTICLES THERETHROUGH AND USING DURING THE MILLING OPERATION, A VOLATILE SOLVENT FOR SOFTENING THE RUBBER-LIKE MATERIAL BUT INERT AS TO THE FILLER, IN SUCH A QUANTITY AS TO ASSIST IN INCORPORATING THE PARTICLES OF FILLER IN THE RUBBER-LIKE MATERIAL WHILE THE RUBBERLIKE MATERIAL REMAINS IN A SOFTENED SOLID STATE, THE SOLVENT ENABLING THE PARTICLES TO BE INCORPORATED IN THE RUBBER-LIKE MATERIAL IN SUCH A MANNER THAT THEY CAN READILY BE REMOVED FROM OBJECTS MOLDED FROM THE BASED-STOCK; SHEETING THE FILLED BASESTOCK FROM THE MILL IN SHEETS HAVING THE DESIRED THICKNESS, AND ALLOWING THE SOLVENT TO EVAPORATE THEREFROM, SAID FILLER MATERIAL BEING SELECTED SO AS TO BE RESISTANT TO A VULCANIZATION PROCESS BUT LEACHABLE FROM THE VULCANIZED PRODUCT.