Patent US4028290A successfully refreshed from Google Patents.
US4028290A
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Highly absorbent modified polysaccharides
Assignee: Hercules LLC
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Filing: 1975-10-23
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Granted: 1977-06-07
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Expires: 1995-10-23
Abstract
Abstract Modified polysaccharides having greatly increased water-absorbing and binding capacity are prepared by reacting a polysaccharide such as cellulose or starch in the presence of acrylamide, another vinyl monomer and a divinyl crosslinking monomer using free radical polymerization techniques. The product is believed to be a complex mixture of crosslinked grafted polysaccharide and acrylamide copolymers.
Inventors
- 👤 Albert R. Reid
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:34
CPC Classifications
C; C08; C08F; C08F251/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
138 words
A method of preparing a modified polysaccharide which exhibits high absorbency for water and salt solutions, which method comprises reacting a water-insoluble, water-swellable polysaccharide simultaneously with acrylamide, at least one other water-soluble monoolefinic vinyl monomer which, in the absence of the polysaccharide, is copolymerizable with acrylamide to form a water-soluble copolymer, and a water-soluble copolymer, and a water-soluble free radical polymerizable divinyl monomer, in the presence of a free radical catalyst system, said reaction being carried out in a reaction medium comprising a substantially water-immiscible inert aromatic hydrocarbon having dispersed therein water equal to about 1.5 to 2.5 times the weight of the aforesaid reactants and a low boiling, water-miscible, organic liquid selected from the class consisting of acetone and isopropyl alcohol, in an amount equal to about 25 to 65% of the volume of the aromatic hydrocarbon.
Claim 2
Independent Claim
138 words
A method of preparing a modified polysaccharide which exhibits high absorbency for water and salt solutions, which method comprises reacting a water-insoluble, water-swellable polysaccharide simultaneously with acrylamide, at least one other water-soluble monoolefinic vinyl monomer which, in the absence of the polysaccharide, is copolymerizable with acrylamide to form a water-soluble copolymer, and a water-soluble copolymer, and a water-soluble free radical polymerizable divinyl monomer, in the presence of a free radical catalyst system, said reaction being carried out in a reaction medium comprising a substantially water-immiscible inert aromatic hydrocarbon having dispersed therein water equal to about 1.5 to 2.5 times the weight of the aforesaid reactants and a low boiling, water-miscible, organic liquid selected from the class consisting of acetone and isopropyl alcohol, in an amount equal to about 25 to 65% of the volume of the aromatic hydrocarbon.
Claim 3
Dependent Claim
24 words
The method according to claim 1 wherein the polysaccharide material is selected from the class consisting of cellulose, oxidized cellulose, starch and guar gum.
Claim 4
Dependent Claim
22 words
The method according to claim 1 wherein the water-immiscible inert liquid is toluene and the low boiling, water-miscible organic liquid is actone.
Claim 5
Dependent Claim
24 words
The method according to claim 3 wherein the polysaccharide material is selectd from the class consisting of cellulose, oxidized cellulose, starch, and guar gum.
Claim 6
Dependent Claim
20 words
The method according to claim 4 wherein the other vinyl monomer is sodium acrylate and the divinyl monomer is methylene-bis-acrylamide.
Claim 7
Dependent Claim
22 words
The method according to claim 5 wherein the acrylamide component of the vinyl monomers is about 20 to 30% by weight thereof.
Claim 8
Dependent Claim
23 words
The method according to claim 3 wherein the amount of acetone is between about 30 and 55% bsed on the volume of toluene.
Claim 9
Independent Claim
81 words
A method of preparing a water-insoluble cellulose derivative having high absorbency for water and salt solutions which comprises reacting cellulose or oxidized cellulose simultaneously with acrylamide, sodium acrylate and methylene-bis-acrylamide in the presence of a free radical catalyst system, said reaction being carried out in a reaction medium comprised of toluene, water equal to 1.5 to 2.5 times the combined weight of the reactants, and acetone in an amount equal to about 30 to 55% of the volume of the toluene.
Claim 10
Independent Claim
81 words
A method of preparing a water-insoluble cellulose derivative having high absorbency for water and salt solutions which comprises reacting cellulose or oxidized cellulose simultaneously with acrylamide, sodium acrylate and methylene-bis-acrylamide in the presence of a free radical catalyst system, said reaction being carried out in a reaction medium comprised of toluene, water equal to 1.5 to 2.5 times the combined weight of the reactants, and acetone in an amount equal to about 30 to 55% of the volume of the toluene.
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) | 1980-06-06 | 1980-12-06 | 1981-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-06 | 1984-12-06 | 1985-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-06 | 1988-12-06 | 1989-06-07 | $7700.00 | Window Closed / Lapsed |