METHOD FOR MANUFACTURING BATTERY SEPARATOR

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a battery separator by performing a sulfonation treatment on nonwoven fabric including a primary component consisting of polyolefin core-sheath type conjugate fiber, which is superior in the effects of: suppressing the occurrence of a defect; suppressing the lowering of the strength; and suppressing the self discharge.SOLUTION: A method for manufacturing a battery separator comprises a step of performing a sulfonation treatment on nonwoven fabric including a primary component consisting of polyolefin core-sheath type conjugate fiber in a mixed gas including a sulfur trioxide gas and a nitrogen gas. In the method, the concentration of the sulfur trioxide gas is 5 vol% or more and to less than 25 vol.%; and the temperature in a reaction tank is over 65°C and 80°C or less.