US4454268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Starch-based semipermeable films
Assignee: United States Department of Agriculture
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Filing: 1983-06-23
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Granted: 1984-06-12
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Expires: 2003-06-23
Abstract
Abstract Semipermeable films useful as dialysis membranes are prepared from starch-based composites. The films are shaped by conventional methods from a plasticized matrix comprising highly gelatinized starch and ethylene acrylic acid copolymer neutralized with a strong alkali. These films are remarkably transparent and resistant to degradation in the presence of aqueous solutions.
Inventors
- 👤 Felix H. Otey
- 👤 Richard P. Westhoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:35
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0009; B01D67/0011; B01D67/00113; B01D71/00; B01D71/06; B01D71/08; C; C08; C08L; C08L3/00; C08L3/02
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
91 words
A method of preparing a semipermeable film comprising the following steps: a. converting a mixture comprising a starchy material (SM), an ethylene acrylic acid copolymer (EAA), and a strong alkali into a plasticized matrix, wherein the ratio of SM:EAA is in the range of 20:80 to about 60:40 parts on a dry weight basis, wherein the strong alkali is present in an amount sufficient to neutralize substantially all of the EAA, and wherein the starchy material in the plasticized matrix is highly gelatinized; and b. shaping said matrix into a film.
Claim 2
Independent Claim
91 words
A method of preparing a semipermeable film comprising the following steps: a. converting a mixture comprising a starchy material (SM), an ethylene acrylic acid copolymer (EAA), and a strong alkali into a plasticized matrix, wherein the ratio of SM:EAA is in the range of 20:80 to about 60:40 parts on a dry weight basis, wherein the strong alkali is present in an amount sufficient to neutralize substantially all of the EAA, and wherein the starchy material in the plasticized matrix is highly gelatinized; and b. shaping said matrix into a film.
Claim 3
Dependent Claim
22 words
A method as described in claim 1 wherein said starchy material is selected from the group consisting of unmodified starches and flours.
Claim 4
Dependent Claim
16 words
A method as described in claim 1 wherein said starchy material is a starch graft copolymer.
Claim 5
Dependent Claim
26 words
A method as described in claim 1 wherein the ratio of SM:EAA is in the range of 30:70 to 50:50 parts on a dry weight basis.
Claim 6
Dependent Claim
14 words
A method as described in claim 1 wherein said strong alkali is sodium hydroxide.
Claim 7
Dependent Claim
30 words
A method as described in claim 5 wherein the conditions of converting said mixture to a plasticized matrix in step (a) are sufficient to effect gelatinization of said starchy material.
Claim 8
Dependent Claim
46 words
A method as described in claim 1 wherein prior to shaping, the moisture content of the plasticized matrix is adjusted to within the range of about 2-10% based on the dry weight of the matrix, and the matrix is shaped into a film by extrusion blowing.
Claim 9
Dependent Claim
18 words
A method as described in claim 1 wherein the mixture of step (a) further comprises a leachable additive.
Claim 10
Dependent Claim
29 words
A method as described in claim 8 wherein said leachable additive is water soluble and is leached from the film by presoaking the film in water prior to use.
Claim 11
Dependent Claim
13 words
A method as described in claim 9 wherein said leachable additive is urea.
Claim 12
Dependent Claim
47 words
A semipermeable film composition comprising a dry composite of highly gelatinized starchy material (SM) and a sodium or potassium salt of ethylene acrylic acid copolymer (EAA), wherein the ratio of SM:EAA copolymer salt is in the range of 20:80 to 60:40 parts on a dry weight basis.
Claim 13
Dependent Claim
47 words
A semipermeable film composition comprising a dry composite of highly gelatinized starchy material (SM) and a sodium or potassium salt of ethylene acrylic acid copolymer (EAA), wherein the ratio of SM:EAA copolymer salt is in the range of 20:80 to 60:40 parts on a dry weight basis.
Claim 14
Dependent Claim
22 words
A composition as described in claim 11 wherein said starchy material is selected from the group consisting of unmodified starches and flour.
Claim 15
Dependent Claim
16 words
A composition as described in claim 11 wherein said starchy material is a starch graft copolymer.
Claim 16
Dependent Claim
28 words
A composition as described in claim 11 wherein the ratio of SM:EAA copolymer salt is in the range of 30:70 to 50:50 parts on a dry weight basis.
Claim 17
Dependent Claim
12 words
A composition as described in claim 11 further comprising a leachable additive.
Claim 18
Dependent Claim
14 words
A composition as described in claim 11 wherein said leachable additive is water soluble.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |