POLYPROPYLENMEMBRANEN.

摘要

There is disclosed a substantially skinless microporous polypropylene membrane characterized by having (a) a bubble point of about 25 to about 50 psi; (b) a thickness of about 3 to about 7 mils; (c) a nitrogen flow rate of at least 0.5 liters per square centimeter-minute; (d) a burst strength of at least 10 psi; and (e) an S value of about 15, or less. There is also disclosed a method of preparing a microporous polypropylene membrane comprising heating a mixture of about 30 percent polypropylene and about 70 percent, N,N-bis(2-hydroxyethyl)tallowamine, by weight, to a temperature and for a time sufficient to form a homogeneous solution, casting or extruding said solution at a thickness of about 3 to about 7 mils, onto a chill roll maintained at a temperature of from about 50 DEG to about 80 DEG C., allowing said solution to solidify on said chill roll to form a solid sheet, removing said solid sheet from said chill roll and removing at least a substantial portion of the liquid from said sheet to form the microporous polypropylene membrane.