Starch-based aqueous adhesive compositions and uses thereof
The invention relates to starch-based aqueous adhesive compositions and uses thereof. Provided is an aqueous adhesive composition comprising highly branched starch (HBS) obtained by treatment of starch or starch derivatives with a glycogen branching enzyme, and further comprising a carboxymethyl (CM) polysaccharide derivative, such as a carboxymethyl ether of starch, cellulose or a combination thereof. Also provided is a method for adhering a first substrate to a second substrate, comprising applying to at least said first or said second substrate said starch-based adhesive, and a glued or glueable product obtainable thereby.
1. An aqueous adhesive composition comprising highly branched starch (HBS) obtained by treatment of starch or starch derivatives with a glycogen branching enzyme (EC 2.4.1.18), and further comprising a carboxymethyl (CM) polysaccharide derivative.
2. Adhesive composition according to claim 1 , wherein said CM polysaccharide derivative is a carboxymethyl ether of starch, cellulose or a combination thereof.
3. Adhesive composition according to claim 1 wherein said CM polysaccharide is derived from a starch selected from the group consisting of native, unmodified and chemically modified starch derived from non-genetically modified or as genetically modified plant variants, such as potato, corn, wheat, tapioca, waxy potato, waxy corn, waxy tapioca, high amylose potato, high amylose corn, and modified starches including low DE maltodextrins and amylomaltase-treated starch.
4. Adhesive composition according to claim 1 , wherein said carboxymethylated polysaccharide is present in an amount of 0.1 to 20% by weight of the total dry weight of the composition.
5. Adhesive composition according to claim 1 , wherein said HBS has a molecular branching degree of at least 6% wherein the molecular branching degree is defined as the percentage of α-1,6 glycosidic linkages of the total of α-1,6 and α-1,4 glycosidic linkages ((α-1,6/(α-1,6+α-1,4)*100%).
6. Adhesive composition according to claim 1 , wherein said HBS is obtained from starch or starch derivatives in a partially or completely gelatinized form, preferably wherein said starch or starch derivative is selected from native, unmodified and chemically modified starch derived from non-genetically modified as well as genetically modified plant variants, such as potato, corn, wheat, tapioca, waxy potato, waxy corn, waxy tapioca, high amylose potato, high amylose corn, and modified starches including low DE maltodextrins and amylomaltase-treated starch.
7. Adhesive composition according to claim 1 , wherein said adhesive composition contains 20-80 wt % dry matter.
8. Adhesive composition according to claim 1 , wherein said HBS is present in the adhesive composition in an amount of from 5 to 75% (w/w) by weight of the total weight of the composition.
9. Adhesive composition according to claim 1 , having a viscosity stability index of less than 1.5, calculated by a quotient of the Brookfield viscosity after 2 weeks, and the Brookfield viscosity after 2 hours after preparation of the composition, wherein the Brookfield viscosity is measured at a temperature of 20° C.
10. Adhesive composition according to claim 1 , having a shear-thinning rheological behavior.
11. Adhesive composition according to claim 1 , having a viscosity index shear rate above 1.2, calculated by a quotient of the viscosity index at a shear rate of 10 s−1 and the viscosity index at 500 s−1, wherein the viscosity is measured at a temperature of 25° C.