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US4885086A Expired / Lapsed US ⏱️ 0.0 years remaining

Hydrophilic microporous membrane and process for preparing same

Assignee: Asahi Kasei Corp
•
Filing: 1988-07-20
•
Granted: 1989-12-05
•
Expires: 2008-07-20
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Abstract

Abstract A hollow fiber microporous membrane of a polyolefin having a polyvinyl alcohol chemically bonded to the inner and outer surfaces of the hollow fiber membrane and the surfaces defining the pores thereof exhibits a good hydrophilic property as well as good chemical resistance, mechanical strength, water permeation performance and durability. This membrane has an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 80%. The polyvinyl alcohol/polyolefin composition ratio is constant in the membrane thickness direction of the hollow fiber, the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 10 to 50%, and the condition defined by the ratio X/2≧Y is satisfied between said oxygen/carbon atomic ratio X and the oxygen/carbon atomic ratio Y in the entire microporous membrane. The membrane is prepared by irradiating a hollow fiber microporous membrane of a polyolefin with ionizing radiations, reacting the membrane with vinyl acetate and then hydrolyzing the membrane.

Inventors

  • 👤 Morikazu Miura

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 22:48
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0081; B01D67/0093; B01D67/00931; B01D69/00; B01D69/08; C; C08; C08J; C08J9/00; C08J9/36; C08J9/40; C08J9/405; B01D2323/00; B01D2323/38; B01D2323/385; C08J2323/00; C08J2323/02

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 141 words
A hollow fiber microporous membrane comprising a polyolefin having a polyvinyl alcohol chemically bonded to the inner and outer surfaces of the hollow fiber membrane and the surfaces defining the pores thereof sufficient to provide a weight loss of not greater than 0.1% if the microporous membrane is washed with hot water at a temperature of higher than 80° C., and having an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 80%, wherein the polyvinyl alcohol-polyolefin composition ratio is constant in the membrane thickness direction of the hollow fiber, the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 10 to 50%, and the condition defined by the ratio X/2≧Y is satisfied between said oxygen/carbon atomic ratio X and the oxygen/carbon atomic ratio Y in the entire microporous membrane.
Claim 2
Dependent Claim 141 words
A hollow fiber microporous membrane comprising a polyolefin having a polyvinyl alcohol chemically bonded to the inner and outer surfaces of the hollow fiber membrane and the surfaces defining the pores thereof sufficient to provide a weight loss of not greater than 0.1% if the microporous membrane is washed with hot water at a temperature of higher than 80° C., and having an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 80%, wherein the polyvinyl alcohol-polyolefin composition ratio is constant in the membrane thickness direction of the hollow fiber, the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 10 to 50%, and the condition defined by the ratio X/2≧Y is satisfied between said oxygen/carbon atomic ratio X and the oxygen/carbon atomic ratio Y in the entire microporous membrane.
Claim 3
Dependent Claim 44 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the pore structure of the membrane is a three-dimensional network structure and the membrane has an inner diameter of 0.1 to 10 mm and a wall thickness of 0.05 to 5 mm.
Claim 4
Dependent Claim 16 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the polyolefin is polyethylene.
Claim 5
Dependent Claim 16 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the polyolefin is polypropylene.
Claim 6
Dependent Claim 31 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 15 to 50%.
Claim 7
Dependent Claim 31 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 20 to 50%.
Claim 8
Dependent Claim 21 words
A hollow fiber microporous membrane as set forth in claim 1, wherein the condition defined by the ratio X/2.5≧Y is satisfied.
Claim 9
Dependent Claim 20 words
A hollow fiber microporous membrane as set forth in claim 1, wherein condition defined by the ratio X/3≧Y is satisfied.

References Cited (Backward Citations)

US4681582A Cited
EP0221046A2 Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1992-12-04 1993-06-05 1993-12-05 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1996-12-04 1997-06-05 1997-12-05 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2000-12-04 2001-06-05 2001-12-05 $7700.00 Window Closed / Lapsed

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