Patent ID: 8147911

Claim:
A process for producing a perforated porous resin base, which comprises the following Steps 1 to 4: Step 1 of impregnating the porous structure of a porous resin base with a liquid or a solution; Step 2 of forming a solid substance from the liquid or the solution impregnated; Step 3 of forming a plurality of perforations extending through from the first surface of the porous resin base having the solid substance within the porous structure to the second surface in the porous resin base; and Step 4 of melting or dissolving the solid substance to remove it from the interior of the porous structure, wherein the porous resin base is a porous resin base which is an expanded polytetrafluoroethylene base having a microstructure comprising fibrils and nodes connected to each other by the fibrils, wherein the liquid used in Step 1 is either a substance having a solidifying point or a melting point within a range of from −150 to 150° C. which is water, an alcohol, a hydrocarbon, a polymer or a mixture of two or more compounds thereof, or a liquid containing a compound capable of forming a solid substance by a chemical reaction, wherein the solution used in Step 1 is a solution containing a soluble polymer, which is in a solid state at a temperature ranging from 15 to 30° C., and a solvent, a solution containing paraffin, which is in a solid state at a temperature ranging from 15 to 30° C., and a solvent, or a solution containing a compound capable of forming a solid substance by a chemical reaction and a solvent, wherein the compound capable of forming a solid substance by a chemical reaction is a polymerizable monomer undergoing a polymerization reaction by heat or light to form a polymer, and wherein the plurality of perforations is formed by a mechanically perforating method or a method of etching by a light abrasion method.