US3997484A
Expired / Lapsed
US
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Highly-absorbent starch-containing polymeric compositions
Assignee: United States Department of Agriculture
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Filing: 1975-09-08
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Granted: 1976-12-14
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Expires: 1995-09-08
Abstract
Abstract Starch-containing polymer compositions are prepared which absorb amounts of water equaling up to more than 1000 times their own weight. The compositions find many applications including their incorporation into products such as disposable diapers, surgical pads and sheets, and paper towels.
Inventors
- 👤 Mary Ollidene Weaver
- 👤 Edward B. Bagley
- 👤 George F. Fanta
- 👤 William M. Doane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:48
CPC Classifications
B; B01; B01J; B01J20/00; B01J20/22; A; A23; A23C; A23C1/00; A23C1/14; A23C1/16; A61; A61L; A61L15/00; A61L15/16; A61L15/42; A61L15/60; B01D; B01D15/00; B01D17/00; B01D17/02; B01D17/0202
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
67 words
Aqueous fluid-absorbing compositions comprising water-insoluble alkali salts of aqueous alkali saponified gelatinized-starch-polyacrylonitrile graft polymers containing gelatinized starch (GS) and saponified polyacrylonitrile (HPAN) in molar ratios of from about 1:1.5 to 1:9 GS:HPAN, said water-insoluble alkali salts of aqueous alkali saponified gelatinized-starch-polyacrylonitrile graft polymers being further characterized as water-insoluble solids capable of absorbing in excess of 300 parts of water by weight per part of said water-insoluble solids.
Claim 2
Dependent Claim
67 words
Aqueous fluid-absorbing compositions comprising water-insoluble alkali salts of aqueous alkali saponified gelatinized-starch-polyacrylonitrile graft polymers containing gelatinized starch (GS) and saponified polyacrylonitrile (HPAN) in molar ratios of from about 1:1.5 to 1:9 GS:HPAN, said water-insoluble alkali salts of aqueous alkali saponified gelatinized-starch-polyacrylonitrile graft polymers being further characterized as water-insoluble solids capable of absorbing in excess of 300 parts of water by weight per part of said water-insoluble solids.
Claim 3
Dependent Claim
43 words
Aqueous fluid-absorbing compositions as described in claim 1 wherein the insoluble alkali salts of aqueous alkali saponified gelatinized-starch-polyacrylonitrile graft polymers are further characterized as water-insoluble solids capable of absorbing from about 300 to 1500 parts by weight per part of said water-insoluble solids.
Claim 4
Dependent Claim
26 words
Aqueous fluid-absorbing compositions as described in claim 1 wherein the gelatinized starch contained therein is wheat starch, corn starch, waxy corn starch, or waxy sorghum starch.
Claim 5
Independent Claim
121 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions comprising the following steps: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to from about 4 to 12 to reform said water-soluble GS-HPAN; and c. drying said water-soluble GS-HPAN to a moisture level of from about 1 to 15% water by weight.
Claim 6
Independent Claim
121 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions comprising the following steps: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to from about 4 to 12 to reform said water-soluble GS-HPAN; and c. drying said water-soluble GS-HPAN to a moisture level of from about 1 to 15% water by weight.
Claim 7
Dependent Claim
33 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions as described in claim 4 wherein the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.6:1 to 7:1.
Claim 8
Dependent Claim
96 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions as described in claim 4 wherein the GS-PAN is prepared by the method comprising the steps of: a. gelatinizing starch (GS) in an aqueous suspension at a temperature of from 80° to 100° C. for at least 15 min.; and b. graft polymerizing the gelatinized starch resulting from step (a) with acrylonitrile (AN) or methacrylonitrile (MAN) in amounts such that the molar ratio of GS to AN or MAN is from about 1:1.5 to 1:9, said graft polymerizing taking place in the presence of a suitable polymerization initiator.
Claim 9
Dependent Claim
28 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions as described in claim 6 wherein the starch is wheat starch, corn starch, waxy corn starch, or waxy sorghum starch.
Claim 10
Independent Claim
128 words
A method of preparing insoluble aqueous-organic fluid-absorbing compositions comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to acrylonitrile repeating units of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); b. adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN; c. reacting said water-insoluble acid form of GS-HPAN in an aqueous slurry with an organic amine in amounts such that the pH of the reaction mixture is from 5 to 11; and d. drying the product of step (c) to a moisture content of about 1 to 15% water by weight.
Claim 11
Independent Claim
128 words
A method of preparing insoluble aqueous-organic fluid-absorbing compositions comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to acrylonitrile repeating units of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); b. adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN; c. reacting said water-insoluble acid form of GS-HPAN in an aqueous slurry with an organic amine in amounts such that the pH of the reaction mixture is from 5 to 11; and d. drying the product of step (c) to a moisture content of about 1 to 15% water by weight.
Claim 12
Dependent Claim
37 words
A method of preparing insoluble aqueous-organic fluid-absorbing compositions as described in claim 8 wherein the organic amine is methyl-, ethyl-, hexyl-, dodecyl-, benzyl-, chlorobenzyl-, or ethanolamine, secondary or tertiary analogs of the same, aniline, cyclohexylamine, or pyridine.
Claim 13
Independent Claim
151 words
A method of preparing a low viscosity aqueous dispersion of a water-soluble saponified gelatinized-starch-polyacrylonitrile graft polymer capable of forming a water-insoluble aqueous, fluid-absorbing composition comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.0:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to form about 4 to 12 to reform said water-soluble GS-HPAN; and c. sonifying a 1% by weight aqueous dispersion of said water-soluble GS-HPAN at a sonifying frequency and for a time sufficient to reduce the viscosity of said dispersion to about 30 cp.
Claim 14
Independent Claim
151 words
A method of preparing a low viscosity aqueous dispersion of a water-soluble saponified gelatinized-starch-polyacrylonitrile graft polymer capable of forming a water-insoluble aqueous, fluid-absorbing composition comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.0:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to form about 4 to 12 to reform said water-soluble GS-HPAN; and c. sonifying a 1% by weight aqueous dispersion of said water-soluble GS-HPAN at a sonifying frequency and for a time sufficient to reduce the viscosity of said dispersion to about 30 cp.
Claim 15
Dependent Claim
42 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions comprising drying a low viscosity aqueous dispersion of a water-soluble saponified gelatinized-starch-polyacrylonitrile graft polymer prepared as described in claim 10 at a temperature of about 160° C. for from about 15 to 120 min.
Claim 16
Dependent Claim
64 words
A method of preparing water-insoluble aqueous fluid-absorbing compositions comprising drying a low viscosity aqueous dispersion of a water-soluble saponified gelatinized-starch-polyacrylonitrile graft polymer prepared as described in claim 10 at a temperature of about 25° C. for from about 7 days in a humid atmosphere having about 90% relative humidity to about 100 days in a humid atmosphere having from 43 to 90% relative humidity.
Claim 17
Independent Claim
138 words
A method of increasing the water absorbency of water-insoluble substrates comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to from about 4 to 12 to reform said water-soluble GS-HPAN; and c. mixing said water-soluble GS-HPAN in an aqueous slurry of a water-insoluble substrate; and d. drying the mixture resulting from step (c) to a moisture content of 1 to 15% water by weight.
Claim 18
Independent Claim
138 words
A method of increasing the water absorbency of water-insoluble substrates comprising the steps of: a. saponifying a gelatinized-starch-polyacrylonitrile graft polymer (GS-PAN) in an aqueous slurry with an alkali in amounts such that the molar ratio of alkali to the acrylonitrile repeating unit of said GS-PAN is from about 0.1:1 to 7:1 to form a water-soluble saponified GS-PAN (water-soluble GS-HPAN); and b. optionally adjusting the pH of said water-soluble GS-HPAN to about 3, followed by isolating the resulting water-insoluble acid form of GS-HPAN, and readjusting the pH of said water-insoluble acid form of GS-HPAN to from about 4 to 12 to reform said water-soluble GS-HPAN; and c. mixing said water-soluble GS-HPAN in an aqueous slurry of a water-insoluble substrate; and d. drying the mixture resulting from step (c) to a moisture content of 1 to 15% water by weight.
Claim 19
Dependent Claim
34 words
A method of increasing the water absorbency of water-insoluble substrates as described in claim 13 wherein the water-insoluble substrate is diatomaceous silica, clay, animal litter or bedding, granular starch, cellulose fibers, paper, or cloth.
Claim 20
Dependent Claim
8 words
Water-absorbent substrates prepared as described in claim 14.
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) | 1979-12-14 | 1980-06-14 | 1980-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-12-14 | 1984-06-14 | 1984-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-12-14 | 1988-06-14 | 1988-12-14 | $7700.00 | Window Closed / Lapsed |