Cationic biopolymers
AssigneesHenkel Kommanditgesellschaft auf Aktien, Norwegian Institute of Fisheries and Aquaculture Ltd.
InventorsRolf Wachter, Holger Tesmann, Ronald Svenning, Ragnar Olsen, Even Stenberg
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Abstract
The invention relates to new cationic biopolymers with an average molecular weight of 800,000 to 1,200,000 Dalton, a Brookfield viscosity (1% by weight in glycolic acid) below 5,000 mPas, a degree of deacetylation of 80 to 88% and an ash content of less than 0.3% by weight which are obtained by repeatedly subjecting crustacean shells to alternate acidic and alkaline degradation under defined conditions. Compared with known cationic biopolymers of the chitosan type, the new biopolymers form clear solutions and, at the same time, show excellent film-forming properties, despite their high molecular weight.
Claims8
A process for making a cationic biopolymer having an average molecular weight of 800,000 to 1,200,000 Dalton, a Brookfield viscosity (1% by weight in glycolic acid) of less than 5,000 mPas, a degree of deacetylation of 80 to 88% and an ash content of less than 0.3% by weight comprising the steps of:
- (a) contacting fresh crustacean shells with dilute aqueous mineral acid to form a first intermediate product;
- (b) contacting said first intermediate product with aqueous alkali metal hydroxide solution to form a second intermediate product;
- (c) contacting said second intermediate product with dilute aqueous mineral acid to produce a third intermediate product;
- (d) contacting said third intermediate product with a concentrated aqueous alkali metal hydroxide solution wherein steps (a) and (c) being carried out at a temperature of from about 15 to about 25.degree. C. and at a pH of from about 0.3 to about 0.7 and steps (b) and (d) being carried out at a temperature of from about 70 to about 110.degree. C. and at a pH of from about 12 to about 14.
A cationic biopolymer made by the process comprising the steps of:
- (a) contacting fresh crustacean shells with dilute aqueous mineral acid to form a first intermediate product;
- (b) contacting said first intermediate product with aqueous alkali metal hydroxide solution to form a second intermediate product;
- (c) contacting said second intermediate product with dilute aqueous mineral acid to produce a third intermediate product;
- (d) contacting said third intermediate product with a concentrated aqueous alkali metal hydroxide solution wherein steps (a) and (c) being carried out at a temperature of from about 15 to about 25.degree. C. and at a pH of from about 0.3 to about 0.7 and steps (b) and (d) being carried out at a temperature of from about 70 to about 110.degree. C. and at a pH of from about 12 to about 14.
Dependencies are inferred from the claim text.