FLUORORESIN MICROPOROUS MEMBRANE, METHOD FOR PRODUCING THE SAME, AND FILTER ELEMENT USING THE FLUORORESIN MICROPOROUS MEMBRANE

摘要

Provided are a fluororesin microporous membrane having a narrow pore-size distribution and a smaller difference between a mean flow pore size and a maximum pore size, a method for producing the fluororesin microporous membrane, and a filter element that uses the fluororesin microporous membrane. The fluororesin microporous membrane is a porous membrane obtained by forming fluororesin particles into a membrane having a particular shape and particular dimensions, baking the fluororesin particles together by heating the membrane to a melting point of the membrane or higher, and then stretching the membrane. The fluororesin particles each have a structure in which a heat of fusion of a fluororesin constituting an outer surface portion of the particle is lower than a heat of fusion of polytetrafluoroethylene constituting an inside portion of the particle.

主权项

1. A fluororesin microporous membrane being a porous membrane obtained by forming fluororesin particles into a membrane having a particular shape and particular dimensions, baking the fluororesin particles together by heating the membrane to a melting point of the membrane or higher, and then stretching the membrane, wherein each of the fluororesin particles has a structure in which an inside portion of the particle is composed of one polytetrafluoroethylene and an outer surface portion of the particle is composed of another polytetrafluoroethylene, a tetrafluoroethylene/hexafluoropropylene copolymer, or a tetrafluoroethylene/perfluoroalkyl ether copolymer whose heat of fusion is lower than that of the one polytetrafluoroethylene.