CHARGE MODIFIED MICROPOROUS MEMBRANE, PROCESS FOR CHARGE MODIFYING SAID MEMBRANE, AND PROCESS FOR FILTRATION OF FLUIDS

摘要

CHARGE MODIFIED MICROPOROUS MEMBRANE, PROCESSFOR CHARGE MODIFYING SAID MEMBRANE, ANDPROCESS FOR FILTRATION OF FLUIDSABSTRACTA cationic charge modified microporous membrane is provided.The membrane comprises a hydrophilic organic polymericmicroporous membrane having bonded thereto, through a cross-linking agent, a charge modifying amount of a cationic chargemodifying agent. The charge modifying agent is an aliphatic amineor polyamine, preferably tetraethylene pentamine, and the cross-linking agent is an aliphatic polyepoxide having a molecular weight ofless than about 500, preferably 1, 4 butanediol diglycidyl ether. Themicroporous membrane is preferably nylon. The process for applyingthe charge modifying agent to the membrane, preferably comprisescontacting the membrane with an aqueouos solution of the chargemodifying agent and then contacting the membrane with a substan-tially aqueous solution of the cross-linking agent. The preferredprocess uses high purity water, i.e. water having no significant ioniccontent, to produce a membrane suitable for use in filtering ultrapure (18 megohm-cm resistivity) water for use in producing electronicdevices. Such a membrane exhibits an advantageously low "flush-out"time compared to known cationic charge modified microporousmembranes and unmodified microporous membranes.