PURPOSE: To adapt an acrylic polymer to battery separators, fluid separation membranes, etc., by treating the polymer with an alkali and then with water.
CONSTITUTION: An acrylic polymer is treated with an alkali and then with water. The acrylic polymer which is used is one having at least 30mol% acrylate ester and/or methacrylate ester as monomer components. Other comonomers include acrylic acid, methacrylic acid, vinyl chloride, ethylene, acrylamide, etc. In case where a hydrophilic monomer such as acrylic acid or maleic acid is used as a comonomer, the content of such a monomer is limited to below 10mol%. The reason for this is to maintain the waterproof property of the acrylic polymer. The above alkali treatment consists of treating an acrylic polymer with an aqueous solution containing at least 5wt% alkali such as caustic soda or calcium hydroxide.
SAWAZAKI TAKASHI
NAKAMURA KIMIYUKI
FURUKAWA BATTERY CO LTD