PURPOSE: To obtain titled porous membrane with adequate corrosion and chlorine resistance, by carrying out a biaxial orientation at a specific temperature of a sulfonyl group-contg. fluorocarbon polymer membrane.
CONSTITUTION: The objective thin membrane can be obtained by carrying out a biaxial orientation at a speed 1.0mm/secW10cm/sec. with a ratio in monoaxial direction being 1.5W10, of a sulfonyl group (pref. -SO2X, X being halogen)-contg. fluorocarbon polymer (e.g., a copolymer from a fluorinated ethylene monomer and a sulfonyl group-contg. fluorinated vinyl monomer, pref. with the latter content being ≥1mol%). The orientation temperature is lower than the melting point of said polymer at least by 50°C. Preferably, the width of the objective membrane falls between 5μ and 150μ.
USE: Cation exchange membranes, etc.
KIYOTA TOORU
ORISAKA KATSUNORI
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