Method of making a composite microporous membrane

摘要

A method of making a composite microporous membrane includes the steps of: coating a nonporous precursor film with a polymer composition, and then stretching the coated nonporous precursor. Stretching includes a first stretching conducted at a first temperature and a first stretching rate and a second stretching conducted at a second temperature and a second stretching rate. The first stretching rate and the second stretching rate are different.