Polysaccharide adhesive

Abstract

The present invention relates to the use of a polysaccharide adhesive containing cold water-soluble or cold water-swelling, covalently cross-linked starch as a binder together with a foam generator for producing an adhesive foam.

Claims

1. A method comprising: obtaining a polysaccharide adhesive comprising cold water-soluble and/or cold water-swellable, completely lysed, covalently cross-linked starch as a binding agent in combination with a foaming agent further defined as comprising at least one anionic, cationic, amphoteric, or nonionic surfactant; and using the polysaccharide adhesive to prepare an adhesive foam.

2. The method of claim 1, further comprising selecting a concentration of the covalently cross-linked starch in the polysaccharide adhesive such that an aqueous, unfoamed suspension of the adhesive has a viscosity within a range of about 1000 to 4000 mPa-s (Brookfield viscosity, 25 C., 100 rpm).

3. The method of claim 2, wherein the concentration of the covalently cross-linked starch in the polysaccharide adhesive is selected such that the aqueous, unfoamed suspension of the adhesive has a viscosity within a range of about 1500 to 2500 mPa-s.

4. The method of claim 1, wherein not more than 70% by mass of the cross-linked starch is substituted by degraded starch.

5. The method of claim 4, wherein not more than 60% by mass of the cross-linked starch is substituted by degraded starch.

6. The method of claim 5, wherein not more than 50% by mass of the cross-linked starch is substituted by degraded starch.

7. The method of claim 4, wherein the degraded starch comprises at least one dextrin, maltodextrin, or enzymatically modified starch.

8. The method of claim 1, wherein the polysaccharide adhesive is comprised in an aqueous, unfoamed suspension that has a solids content of more than 15% by mass of the suspension.

9. The method of claim 8, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 20% by mass of the suspension.

10. The method of claim 9, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 30% by mass of the suspension.

11. The method of claim 10, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 35% by mass of the suspension.

12. The method of claim 11, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 40% by mass of the suspension.

13. The method of claim 1, further comprising foaming an aqueous suspension of the polysaccharide adhesive.

Description

COMPARATIVE EXPERIMENTS

(1) Adhesive foams on the basis of roasted dextrins have already been described in WO 2002/00804 and in the U.S. Pat. No. 6,280,514 B1 and U.S. Pat. No. 6,280,515 B1. Table 8 shows the properties of these adhesive foams. The mixtures A and C disclosed in U.S. Pat. No. 6,280,514 B1 exhibited foams having a significantly increased viscosity which are not processable in practice. Moreover, mixture A could not be adequately foamed. Furthermore, the mixtures contain borax, which has been categorized as toxic and merely provides a reversible cross-linking of the starch and/or starch products employed. While omitting borax from the formulation will yield lower viscosities, it does not provide any bonding effect.

(2) The mixtures A to C disclosed in U.S. Pat. No. 6,280,515 B1 did not exhibit sufficient adhesive strengths; moreover, both mixture A and mixture C could not be foamed.

(3) TABLE-US-00009 TABLE 9 Results of comparative experiments Starch Conc. Visc. Foam density Glue basis [%] [mPa-s] [g/mL] Adh. strength [s] WO 02/00804 A AS 2 63 >10000 1.0 59 WO 02/00804 C AS 3 63 >10000 0.6 45 WO 02/00804 A* AS 2 61 2300 0.9 >180 WO 02/00804 C* AS 3 55 1440 0.5 >180 WO 02/00804 A AS 2 33 78 1.0 >180 U.S. Pat. No. 6,280,514 B1 B AS 3 33 1400 0.3 >180 U.S. Pat. No. 6,280,514 B1 C AS 2/AS 3 33 173 1.0 >180 *formulation without borax