MICROPORE FILM MADE OF MODIFIED POLYTETRAFLUOROETHYLENE AND METHOD OF MANUFACTURING THE SAME, POROUS RESIN FILM COMPOSITE, AND FILTER ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide: a method of manufacturing a micropore film made of modified polytetrafluoroethylene in which a difference between an average flow rate pore size and the maximum pore size is small and that is excellent in permeability; the micropore film manufactured by the manufacturing method; a porous resin film composite using the micropore film; and a filter element using the porous resin film composite.SOLUTION: A method of manufacturing a micropore film made of modified polytetrafluoroethylene comprises: heating a film obtained by forming particles of modified polytetrafluoroethylene to a given shape dimension, at higher temperature than a melting point thereof to be non-porous; and then stretching the resultant film to be porous, wherein an amount of heat of fusion of the modified polytetrafluoroethylene is less than 32 J/g, and the stretching step has a low temperature stretching process and a high temperature stretching step. In addition, the micropore film manufactured by the manufacturing method, a porous resin film composite obtained by using the micropore film, and a filter element obtained by using the porous resin film composite are disclosed.