Patent ID: 9421499
Filing Date: 2016-08-23
CPC Classification: B01D

Claim Text:
1. A microporous modified-polytetrafluoroethylene membrane, being a microporous membrane produced by the steps of: producing a copolymer of hexafluoropropylene or perfluoroalkyl ether and tetrafluoroethylene having the number of moles not less than 100 times that of the hexafluoropropylene or perfluoroalkyl ether; forming the copolymer into the shape of a membrane; heating the membrane to the melting point of the copolymer or above to bake the copolymer; cooling the obtained baked product, the baked product having a Gurley second of 5,000 seconds or more before stretching; and subsequently stretching the baked product; the microporous modified-polytetrafluoroethylene membrane having a mean flow pore diameter of 30 nm or less.