METHOD FOR MANUFACTURING POLYMER ELECTROLYTE MEMBRANE

摘要

PROBLEM TO BE SOLVED: To manufacture a product which has only a small amount of a salt remaining in a polymer electrolyte membrane and is industrially uniform without generating a large amount of waste liquid in a step of converting a polymer electrolyte precursor membrane to the polymer electrolyte membrane having a protonic conductivity by exchanging an acid metal salt group in the precursor for protons in an acidic solution to convert the salt group into an acid group.

SOLUTION: The exchange efficiency is greatly enhanced by carrying out the conversion from a metal salt to an acid group in a manufacture process by contacting with an acidic solution twice or more times; the exchange efficiency is held at a stable level by converting a small amount of the remaining metal salt in which a most part thereof has been converted by the first contacting, in the second or successive contacting; and a large waste liquid reduction effect is concurrently acquired by making a state in which the salt concentration in the acidic solution is just concentrated from the downstream side to the upstream side of each acidic solution tank and by taking the waste liquid from the uppermost stream.

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