US 8,075,818 B2 · Method of producing a microporous polyolefin membrane

Abstract

A method for producing a microporous polyolefin membrane formed by fine fibrils, the membrane comprising (A) a polyolefin having a weight-average molecular weight of 5×105 or more or (B) a composition containing Component (A), connected to each other, and having micropores of 0.05 to 5 μm in average pore size and crystal lamellas of Component (A) or (B) being in a specific alignment state. The method includes extruding a solution of Component (A) or (B) in a solvent into a gel-like formed article; thermally setting the article, with or without stretching, at least at the crystal dispersion temperature of Component (A) or (B), but at melting point of Component (A) or (B) plus 30° C. or lower; and removing the solvent.

Claims16

Dependent claims

A method of producing a microporous polyolefin membrane, comprising the steps of

extruding a solution comprising
10 to 50 weight % of a polyolefin (A) having a weight-average molecular weight of 5×105 or more, or a composition (B) containing polyolefin (A) and
50 to 90 weight % of a solvent
into a gel-like formed article;
and then
thermally setting the article, with or without stretching, at least at the crystal dispersion temperature of said polyolefin (A) or said composition (B), but at the melting point of said polyolefin (A) or said composition (B) plus 30° C. or lower;
and subsequently
removing the solvent.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application

10/973,392Filed 27 Oct 2004 · division

Priority

JP 10-29463910 Oct 1998

Published

US 2005/0058823 A117 Mar 2005

Granted

13 Dec 2011

Term ends

Not estimatedThe source records don’t support an estimate.

Classification26 codes

B01D 67/0027
By mechanical treatment, e.g. pore-stretching: by stretching
B01D 67/0009
Organic membrane manufacture: by phase separation, sol-gel transition, evaporation or solvent quenching
B01D 67/003
By inducing porosity into non porous precursor membranes: by selective elimination of components, e.g. by leaching
B01D 69/02
Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes…:…

Method of producing a microporous polyolefin membrane

Life of this patent

Method of producing a microporous polyolefin membrane

Life of this patent

Abstract

Claims16