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.-6. (canceled)

7. 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.

8. The method of claim 7, 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).

9. The method of claim 8, 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.

10. The method of claim 7, wherein not more than 70% by mass of the cross-linked starch is substituted by degraded starch.

11. The method of claim 10, wherein not more than 60% by mass of the cross-linked starch is substituted by degraded starch.

12. The method of claim 11, wherein not more than 50% by mass of the cross-linked starch is substituted by degraded starch.

13. The method of claim 10, wherein the degraded starch comprises at least one dextrin, maltodextrin, and/or enzymatically modified starch.

14. The method of claim 7, wherein an aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 15% by mass of the suspension.

15. The method of claim 14, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 20% by mass of the suspension.

16. The method of claim 15, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 30% by mass of the suspension.

17. The method of claim 16, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 35% by mass of the suspension.

18. The method of claim 17, wherein the aqueous, unfoamed suspension containing the polysaccharide adhesive has a solids content of more than 40% by mass of the suspension.

19. The method of claim 7, further comprising foaming the aqueous suspension of the polysaccharide adhesive.

Description

COMPARATIVE EXPERIMENTS

[0081] 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.

[0082] 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.

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