Microporous membrane of cellulose nitrate and cellulose acetate blend

摘要

Microporous membranes formed from a polymer blend of cellulose nitrate and cellulose acetate, having a symmetrical structure and formed directly on a polyester support film. The supported membranes are made by (A) adding 6-13wt.% water to the soln. comprising (by wt.) 5-15% cellulose nitrate, 0.5-0.075% cellulose acetate, 20-40% ethanol, 5-15% butanol and a remainder of methyl acetate to form a casting soln. in which the cellulose nitrate and cellulose acetate are present in dissolved and reprecipitated form, (B) coating a polyester support with the casting soln. and (C) causing phase inversion by evapn. of the volatile materials.