Patent US843827A successfully refreshed from Google Patents.
US4073733A
Expired / Lapsed
US
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PVA membrane and method for preparing the same
Assignee: Kuraray Co Ltd
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Filing: 1976-04-22
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Granted: 1978-02-14
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Expires: 1996-04-22
Abstract
Abstract A polyvinyl alcohol semi-permeable membrane is prepared which has micropores with an average diameter of 0.02 to 2 microns as defined by the interpore partition walls having thicknesses in the range of 50 to 5000 A and which is characterized by substantial cross-sectional uniformity. The membrane is prepared by extruding a PVA composition containing PAG with a molecular weight of 400 to 4,000 and a carbon-to-oxygen ratio of not more than 3 in a proportion of 2 to 200 parts by weight per 100 parts of PVA into a coagulation bath. In another embodiment of the invention, the membrane is formed from a PVA composition wherein the PAG has a molecular weight of 600 to 3,000 and a C/O ratio of not more than 3, the proportion of the PAG being 15 to 150 parts by weight per 100 parts of PVA and wherein the composition satisfies the relation: 0.65 </= CBR (critical blending ratio) </= 1.0. The membrane is useful in ultrafiltration, dialytic and osmotic separation applications.
Inventors
- 👤 Kazuhisa Yamauchi
- 👤 Koichi Takakura
- 👤 Syuji Kawai
- 👤 Akio Ohmori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:38
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/02; B01D71/00; B01D71/06; B01D71/38; B01D71/381; Y; Y10; Y10S; Y10S521/00; Y10S521/905; Y10S521/921
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
93 words
A polyvinyl alcohol membrane prepared by the process which comprises: extruding an aqueous PVA polymer composition containing a polyalkylene glycol having an average molecular weight of 600 to 3,000 and a carbon-to-oxygen atom ratio of not more than 3 in a proportion of 15 to 150 part by weight per 100 parts by weight of PVA, wherein said composition satisfies the relationship: 0.65 ≦ CBR ≦ 1.0; wherein CBR is defined as the critical blending ratio onto a coagulation bath and coagulating the extruded composition such that a resultant shaped article is formed.
Claim 2
Dependent Claim
93 words
A polyvinyl alcohol membrane prepared by the process which comprises: extruding an aqueous PVA polymer composition containing a polyalkylene glycol having an average molecular weight of 600 to 3,000 and a carbon-to-oxygen atom ratio of not more than 3 in a proportion of 15 to 150 part by weight per 100 parts by weight of PVA, wherein said composition satisfies the relationship: 0.65 ≦ CBR ≦ 1.0; wherein CBR is defined as the critical blending ratio onto a coagulation bath and coagulating the extruded composition such that a resultant shaped article is formed.
Claim 3
Dependent Claim
20 words
The PVA membrane of claim 1, wherein said micropores are arranged with substantial uniformity over the entire sectional area thereof.
Claim 4
Dependent Claim
23 words
The PVA membrane of claim 1, wherein said micropores vary in diameter continuously from one side of the membrane to the other side.
Claim 5
Dependent Claim
43 words
The semi-permeable membrane of claim 1, wherein the membrane, on at least either side thereof, has a superficial skin layer, the thickness of which is within the range of about 1 to about 50 times the average thickness of said interpore partition walls.
Claim 6
Dependent Claim
21 words
The membrane of claim 1, which has a water permeability as high as 0.5 to 200 cc/hr atm cm 2 .
Claim 7
Dependent Claim
30 words
The membrane of claim 1, which can withstand a pressure of at least 2 kg/cm 2 at a water permeability of 100 × 10 -2 cc/hr atm cm 2 .
Claim 8
Dependent Claim
26 words
The PVA membrane of claim 1, wherein said micropores vary in diameter in a stepwise fashion from one side of said membrane to the other side.
Claim 9
Dependent Claim
18 words
The membrane of claim 1, which is a flat membrane having a thickness of 5 ˜ 2,000 μ.
Claim 10
Dependent Claim
26 words
The membrane of claim 1, which is a hollow fiber having an outside diameter of 50 ˜ 3,000 μand a thickness of 10 ˜ 500 μ.
Claim 11
Dependent Claim
32 words
The PVA membrane of claim 1, wherein the membrane has been subjected to an acetalization treatment with at least one monoaldehyde selected from the group consisting of formaldehyde, acetaldehyde, chloroacetoladehyde and benzaldehyde.
Claim 12
Dependent Claim
30 words
The PVA membrane of claim 1, wherein said membrane has been subjected to an acetalization treatment with a dialdehyde selected from the group consisting of glutaraldehyde, glyoxal and PVA dialdehyde.
Claim 13
Dependent Claim
11 words
The PVA membrane of claim 11, wherein said dialdehyde is glutaraldehyde.
Claim 14
Independent Claim
93 words
A method of producing a polyvinyl alcohol membrane, which comprises: extruding an aqueous PVA polymer composition containing a polyalkylene glycol having an average molecular weight of 600 to 3,000 and a carbon-to-oxygen atom ratio of not more than 3 in a proportion of 15 to 150 parts by weight per 100 parts by weight of PVA, wherein said composition satisfies the relationship: 0.65 ≦ CBR ≦ 1.0; wherein CBR is defined as the critical blending ratio onto a coagulation bath and coagulating the extruded composition such that a resultant shaped article is formed.
Claim 15
Independent Claim
93 words
A method of producing a polyvinyl alcohol membrane, which comprises: extruding an aqueous PVA polymer composition containing a polyalkylene glycol having an average molecular weight of 600 to 3,000 and a carbon-to-oxygen atom ratio of not more than 3 in a proportion of 15 to 150 parts by weight per 100 parts by weight of PVA, wherein said composition satisfies the relationship: 0.65 ≦ CBR ≦ 1.0; wherein CBR is defined as the critical blending ratio onto a coagulation bath and coagulating the extruded composition such that a resultant shaped article is formed.
Claim 16
Dependent Claim
77 words
A method of claim 13, wherein the PVA polymer of said composition is selected from the group consisting of vinyl alcohol homopolymers having an average polymerization degree in the range of 500 to 3,500 and a saponification degree in the range of 85 to 100 mole percent; PVA copolymers containing less than 10 mole percent of an ethylene, vinylpyrrolidone, vinyl chloride, methyl methacrylate, acrylonitrile or itaconic monomer or mixtures thereof; and derivatives of said homopolymers and copolymer.
Claim 17
Dependent Claim
27 words
The method of claim 13, wherein said polyalkylene glycol is polyethylene glycol, polypropylene glycol or copolymers of said glycols with glycols containing more than four carbon atoms.
Claim 18
Dependent Claim
20 words
The method of claim 13, wherein the critical blending ratio is within the limits of 0.80 ≦ CBR ≦ 1.0.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-13 | 1981-08-15 | 1982-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-13 | 1985-08-15 | 1986-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-13 | 1989-08-15 | 1990-02-14 | $7700.00 | Window Closed / Lapsed |