| 摘要 |
<p>The present invention relates to a porous or microporous film of a high molecular weight polyolefin excellent in strength and air-permeability and suita ble for use in filtering materials, separators for aqueous electrolyte batteries, separa tor films for batteries, separator films for electrolytic capacitors, and air-permeable fi lms; for moisture-permeable water-proof use such as paper diapers and house-wrapping film s; and for other uses such as cloths, package and printing, as well as a process fo r producing same. The feature of the present invention resides in an aspect that t he film is composed of fibrils comprising extended-chain crystals and lamellar crys tals and/or fibrils comprising helicoidal crystals. This porous film of a high molecular weight polyolefin is produced by subjecting an air-impermeable film of a high molecular weight polyolefin to ther mal treatment followed by, if necessary, a stretching treatment and/or a thermosetti ng treatment.</p> |
