Biodegradable absorbent material and method of manufacture
OwnerWilliam Chambers, Paul McClellandinventors
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Abstract
Biodegradable graft copolymers derived from a carbohydrate, including nitrogen-containing carbohydrates and modified carbohydrates, and at least one α,β-unsaturated carboxylic acid derivative having superabsorbent properties are disclosed in addition to the substantially adiabatic polymerization process by which the graft copolymers are made. The methods disclosed can be carried out in a variety of currently available stirred and/or continuous commercial reactors. Polymerizations carried out with starch have surprisingly produced substantially quantitative yields of graft copolymer free of residual monomer produced as a moist copolymer. Product work-up typically involves an optional neutralization and drying.
Claims22
A method for forming a graft copolymer comprising:
- (a) combining water, at least two polysaccharides, at least one α,β-unsaturated carboxylic acid derivative and a catalyst to form a combination having a current temperature and an activation temperature;
- (b) causing the current temperature to sufficiently exceed the activation temperature to thermally initiate a substantially adiabatic polymerization;
- wherein the at least two polysaccharides include a first polysaccharide that is a starch, a second polysaccharide that is a nitrogen-containing polysaccharide;
- and
- wherein the α,β-unsaturated carboxylic acid derivative is selected from the group consisting of an acid, an ester, an amide, an amidine, and a salt.
A method for forming a graft copolymer comprising:
- (a) combining water, a modified polysaccharide, at least one α,β-unsaturated carboxylic acid derivative and a catalyst to form a combination having a current temperature and an activation temperature;
- (b) causing the current temperature to sufficiently exceed the activation temperature to thermally initiate a substantially adiabatic polymerization;
- wherein the α,β-unsaturated carboxylic acid derivative is selected from the group consisting of an acid, an ester, an amide, an amidine, and a salt, and
- wherein the modified polysaccharide is selected from the group consisting of an oxidized polysaccharide, an acid treated polysaccharide, and a combination thereof.
A method for forming a graft copolymer comprising:
- (a) combining water, at least one polysaccharide, and at least one α,β-unsaturated carboxylic acid derivative to form a combination having a current temperature,
- (b) providing a catalyst having an activation temperature;
- (c) causing the combination's current temperature to be at least equal the catalyst's activation temperature;
- and
- (d) introducing the catalyst to the combination having a current temperature of at least the catalyst's activation temperature to thermally initiate a substantially adiabatic polymerization;
- wherein the α,β-unsaturated carboxylic acid derivative is selected from the group consisting of an acid, an ester, an amide, an amidine, and a salt, and
- wherein the at least one polysaccharide is selected from the group consisting of an oxidized polysaccharide, an acid treated polysaccharide, a nitrogen-containing polysaccharide, and a combination thereof.
Dependencies are inferred from the claim text.