Biodegradable absorbent material and method of manufacture
OwnerWilliam Chambersinventor
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Abstract
Biodegradable graft copolymers derived from a carbohydrate 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 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.
Claims26
A method for forming a graft copolymer comprising:
- (a) combining water, a carbohydrate, 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 and provide a free-flowing copolymer;
- 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 said causing the current temperature to sufficiently exceed the activation temperature involves causing said combination to be heated to at least about 180° F.
A method for forming a graft copolymer comprising:
- (a) combining water, a carbohydrate, at least one α,β-unsaturated carboxylic acid derivative and a catalyst to form a combination having an activation temperature;
- (b) contacting said combination with a surface heated to a temperature at or above the activation temperature to initiate and complete polymer formation under substantially adiabatic conditions within less than about 5 minutes to provide a free-flowing copolymer;
- wherein said α,β-unsaturated carboxylic acid derivative is selected from the group consisting of an acid, an ester, an amide, and a salt, and said catalyst is capable of initiating polymerization when subjected to the temperature at or above the activation temperature.
A method for forming a graft copolymer comprising:
- (a) combining water, a carbohydrate, 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 and provide a free-flowing copolymer;
- 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 causing the current temperature to sufficiently exceed the activation temperature occurs within a thermal screw reactor.
Dependencies are inferred from the claim text.