| 摘要 |
<p>There is disclosed a substantially skinless microporous polypropylene membrane characterized by having
<UnorderedLists id="ula01" listStyle="none"><ListItem>(a) a bubble point in the range of from 25 to 50 psi;</ListItem><ListItem>(b) a thickness in the range of from 3 to 7 mils;</ListItem><ListItem>(c) a nitrogen flow rate of at least 0.5 liters per square centimeter-minute;</ListItem><ListItem>(d) a burst strength of at least 10 psi; and</ListItem><ListItem>(e) an S value of about 15, or less.</ListItem></UnorderedLists></p><p>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 in the range of from 3 to 7 mils, onto a chill roll maintained at a temperature in the range of from 50 to 80°C, allowing the solution to solidify on the chill roll to form a solid sheet, removing the solid sheet from the chill roll and removing at least a substantial portion of the liquid from the sheet to form the microporous polypropylene membrane.</p> |
