The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 28, 1998
Filed:
Jul. 24, 1997
Tonen Chemical Corporation, Tokyo, JP;
Abstract
A method of producing a microporous polyolefin membrane having a relatively large pore size and a high permeability, the membrane being suitable for use in water treatment, microfiltration, etc. The method comprises dissolving a polyolefin composition in a solvent to prepare a solution, extruding the solution through a die lip into a form of gel-like sheet, rapidly cooling the gel-like sheet, removing a residual solvent in the cooled sheet by a washing solvent, and drying the resultant sheet to remove the washing solvent. The polyolefin composition is a mixture of (A) an ultra high molecular weight polyolefin having a weight average molecular weight of 5.times.10.sup.5 or more and (B) a polyolefin having a weight average molecular weight less than 5.times.10.sup.5, and a weight ratio of (B)/(A) is 0.2 to 20.