US4952550A
Expired / Lapsed
US
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Particulate absorbent material
Assignee: National Academy of Sciences
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Filing: 1990-03-08
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Granted: 1990-08-28
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Expires: 2010-03-08
Abstract
Abstract The present invention features methods of making absorbent material which exhibit excellent absorption for saline and other liquids as well as being biodegradable. The methods of the invention form a particulate which can be stored in dry form and rehydrated at any time. The particulate can be used to replace the presently utilized polyacrylate superabsorbers. The base material used in the methods of the invention is a carboxylated cellulosic material such as carboxymethylcellulose, preferably, a carboxymethylcellulose having a DS, or Degree of Substitution, of 0.5 or greater. The carboxylated cellulose material is reacted with two distinct agents; a cross-linking agent and a hydrophobicity agent to make the final absorbent.
Inventors
- 👤 Donald F. H. Wallach
- 👤 An-Cheng Chang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:07
CPC Classifications
A; A61; A61L; A61L15/00; A61L15/16; A61L15/42; A61L15/60; A61F; A61F13/00; A61F13/15; A61F13/15203; A61F13/15252; A61L15/22; A61L15/28; A61F13/51; A61F2013/51059; A61F2013/51061; A61F13/53; A61F2013/530481; A61F2013/530583; A61F2013/530649; A61F2013/530795; A61F13/534; A61F2013/53481; A61F13/84; A61F13/8405; A61F2013/8438; A61F2013/8447; A61F2013/8452
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
55 words
A method of making a particulate absorbent material comprising the steps of: A. reacting a carboxylated cellulosic material with i. a cross-linking agent, and ii. a hydrophobicity agent; B. separating the reaction product; and C. removing water from said reaction product until it is substantially dehydrated and a particulate is formed of said absorbent material.
Claim 2
Independent Claim
55 words
A method of making a particulate absorbent material comprising the steps of: A. reacting a carboxylated cellulosic material with i. a cross-linking agent, and ii. a hydrophobicity agent; B. separating the reaction product; and C. removing water from said reaction product until it is substantially dehydrated and a particulate is formed of said absorbent material.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said carboxylated cellulosic compound is selected from the group consisting of carboxymethylcellulose with DS valves of 0.5 or greater.
Claim 4
Dependent Claim
23 words
The method of claim 2 wherein said carboxymethylcellulose reacts with said cross-linking agent before the reaction of said carboxymethylcellulose with said hydrophobicity agent.
Claim 5
Dependent Claim
23 words
The method of claim 2 wherein said carboxymethylcellulose reacts with said hydrophobicity agent before the reaction of said carboxymethylcellulose with said cross-linking agent.
Claim 6
Dependent Claim
30 words
The method of claim 2 wherein said cross-linking agent is selected from the group consisting of cross-linking agents which include a metal having an effective valence of at least 3.
Claim 7
Dependent Claim
23 words
The method of claim 5 wherein said metal ion is selected from the group consisting of aluminum ions, chromium ions, and iron ions.
Claim 8
Dependent Claim
27 words
The method of claim 6 wherein said cross-linking agents are selected from the group consisting of aluminum acetate, aluminum isopropoxide, aluminum hydroxide, ferric chloride, and mixtures thereof.
Claim 9
Dependent Claim
27 words
The method of claim 2 wherein said hydrophobicity agent is selected from the group consisting of monobasic and polybasic carboxylic acids and salts, chlorides, and anhydrides thereof.
Claim 10
Dependent Claim
31 words
The method of claim 8 wherein said carboxylic acid is selected from the group consisting of monobasic and polybasic carboxylic acids having 2-16 carbon atoms, and salts, chlorides, and anhydrides thereof.
Claim 11
Dependent Claim
50 words
The method of claim 9 wherein said carboxylic acid agent is selected from the group consisting of acetic acid, proprionic acid, butyric acid, isobutyric acid, acetic chloride, sodium acetate, sodium propionate, proprionyl chloride, sodium butyrate, acetic anhydride, proprionyl anhydride, succinic acid, adipic acid, phthalic acid, citric acid, and mixtures thereof.
Claim 12
Dependent Claim
29 words
The method of claim 2 wherein said reactions of said carboxymethylcellulose with said cross-linking agent and said carboxymethylcellulose with said hydrophobicity agent are carried out in an organic solvent.
Claim 13
Dependent Claim
29 words
The method of claim 2 wherein said reactions of said carboxymethylcellulose with said cross-linking agent and said carboxymethylcellulose with said hydrophobicity agent are carried out in an aqueous solvent.
Claim 14
Dependent Claim
24 words
The method of claim 12 wherein said carboxymethylcellulose is pre-swollen in an aqueous solution before reaction with said cross-linking agent and said hydrophobicity agent.
Claim 15
Independent Claim
92 words
A method of making a particulate absorbent comprising the steps of: forming an emulsion of carboxymethylcellulose having a DS greater than 0.5 in an organic solvent; reacting said carboxymethylcellulose with a cross-linking agent selected from the group consisting of primary and secondary chromium and aluminum alkoxides, ferric chloride, aluminum and chromium hydroxides, aluminum and chromium acetates, and mixtures thereof; reacting the carboxymethylcellulose with a hydrophobicity agent selected from the group consisting of monobasic and polybasic carboxylic acids having 2-16 carbon atoms, and salts, chlorides, and anhydrides thereof; and removing said organic solvent.
Claim 16
Independent Claim
92 words
A method of making a particulate absorbent comprising the steps of: forming an emulsion of carboxymethylcellulose having a DS greater than 0.5 in an organic solvent; reacting said carboxymethylcellulose with a cross-linking agent selected from the group consisting of primary and secondary chromium and aluminum alkoxides, ferric chloride, aluminum and chromium hydroxides, aluminum and chromium acetates, and mixtures thereof; reacting the carboxymethylcellulose with a hydrophobicity agent selected from the group consisting of monobasic and polybasic carboxylic acids having 2-16 carbon atoms, and salts, chlorides, and anhydrides thereof; and removing said organic solvent.
Claim 17
Dependent Claim
21 words
The method of claim 14 wherein said reaction with said hydrophobicity agent takes place before the reaction with said cross-linking agent.
Claim 18
Dependent Claim
21 words
The method of claim 14 wherein said reaction with said cross-linking agent takes place before the reaction with said hydrophobicity agent.
Claim 19
Independent Claim
91 words
A method of making a particulate absorbent comprising the steps of: swelling particulates of carboxymethylcellulose having a DS greater than 0.5 in an aqueous solvent; reacting said carboxymethylcellulose with a cross-linking agent selected from the group consisting of primary and secondary chromium and aluminum alkoxides, ferric chloride, aluminum and chromium hydrates, aluminum and chromium acetates, and mixtures thereof; reacting the carboxymethylcellulose with a hydrophobicity agent selected from the group consisting of monobasic and polybasic carboxylic acids havings 2-16 carbon atoms, and salts, chlorides, and anhydrides thereof; and removing said aqueous solvent.
Claim 20
Independent Claim
91 words
A method of making a particulate absorbent comprising the steps of: swelling particulates of carboxymethylcellulose having a DS greater than 0.5 in an aqueous solvent; reacting said carboxymethylcellulose with a cross-linking agent selected from the group consisting of primary and secondary chromium and aluminum alkoxides, ferric chloride, aluminum and chromium hydrates, aluminum and chromium acetates, and mixtures thereof; reacting the carboxymethylcellulose with a hydrophobicity agent selected from the group consisting of monobasic and polybasic carboxylic acids havings 2-16 carbon atoms, and salts, chlorides, and anhydrides thereof; and removing said aqueous solvent.
Claim 21
Dependent Claim
22 words
The method of claim 17 wherein said reaction with said hydrophobicity agent is carried out before said reaction with said cross-linking agent.
Claim 22
Dependent Claim
22 words
The method of claim 17 wherein said reaction with said cross-linking agent is carried out before said reaction with said hydrophobicity agent.
Claim 23
Dependent Claim
27 words
The method of claim 17 wherein said carboxymethylcellulose is reacted with an alcohol before the reaction with said cross-linking agent and the reaction with said hydrophobicity agent.
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