PROCESS FOR PREPARING HIGHLY PERMEABLE MICROPOROUS POLYOLEFIN FILM

Title:

PROCESS FOR PREPARING HIGHLY PERMEABLE MICROPOROUS POLYOLEFIN FILM

Document Type and Number:

WIPO Patent Application WO/1999/021914

Kind Code:

A1

Abstract:

A process for preparing a highly permeable microporous polyolefin film, characterized by extruding, at a draft ratio ranging from 3 to 50, a polyolefin solution comprising 5 to 40 % by weight of either a polyolefin having a weight-average molecular weight ranging from 3x10?5¿ to less than 1x10?6¿ and a weight-average molecular weight/number-average molecular weight ranging from 5 to 300 or a polyolefin composition having as a whole a weight-average molecular weight ranging from 3x10?5¿ to less than 1x10?6¿ and a weight-average molecular weight/number-average molecular weight ranging from 5 to 300 and 95 to 60 % by weight of a solvent, melt stretching the extrudate monoaxially, cooling and solidifying the stretched extrudate to form a gel, removing the residual solvent from the gel followed by drying, and heat setting the dried gel at a temperature ranging from 80 °C to the melting point thereof. Monoaxially stretching the viscous polyolefin solution in a molten state serves not only to increase the average pore diameter of the micropores to thereby improve the permeability of the microporous polyolefin film, but also to increase the rate of film preparation to thereby improve the productivity drastically.

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Inventors:

KAIMAI NORIMITSU (JP)
TAKITA KOTARO (JP)
KONO KOICHI (JP)
FUNAOKA HIDEHIKO (JP)

Application Number:

PCT/JP1998/004241

Publication Date:

May 06, 1999

Filing Date:

September 21, 1998

Export Citation:

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Assignee:

TONEN SEKIYUKAGAKU KK (JP)
KAIMAI NORIMITSU (JP)
TAKITA KOTARO (JP)
KONO KOICHI (JP)
FUNAOKA HIDEHIKO (JP)

International Classes:

B01D67/00; B01D71/26; B29C55/00; B29C67/20; (IPC1-7): C08J9/00

Foreign References:

JPH0931226A	1997-02-04
JPH0987413A	1997-03-31

Other References: