Aqueous solutions containing a complexing agent in high concentration

Abstract

Aqueous solution comprising (A) in the range of from 30 to 60% by weight of a complexing agent, selected from the alkali metal salts of methylglycine diacetic acid and the alkali metal salts of glutamic acid diacetic acid, (B) in the range of from 1 to 25% by weight of at least one salt of a sulfonic acid or of an organic acid, percentages referring to the total respective aqueous solution.

Claims

1. An aqueous solution, comprising: (A) from 30 to 60% by weight of a complexing agent, which is selected from the group consisting of an alkali metal salt of methylglycine diacetic acid and an alkali metal salt of glutamic acid diacetic acid, and (B) from 1 to 25% by weight of at least one salt of a sulfonic acid or of an organic acid, based on a total weight of the aqueous solution, wherein the aqueous solution is free from surfactants, wherein the aqueous solution has a total solids content from 31 to 65% by weight, and wherein a pH of the aqueous solution is from 9 to 14.

2. The aqueous solution according to claim 1 having the pH value of from 9 to 13.

3. The aqueous solution according to claim 1, wherein (B) is at least one alkali metal salt of acetic acid, tartaric acid, lactic acid, maleic acid, fumaric acid, or of malic acid.

4. The aqueous solution according to claim 1, wherein (B) is at least one alkali metal salt of methyl sulfonic acid.

5. The aqueous solution according to claim 1, further comprising: (C) a polyethylene glycol having an average molecular weight M.sub.n of from 400 to 10,000 g/mol.

6. A process for making the aqueous solution according to claim 1, the process comprising combining the complexing agent (A) with the salt (B), thereby forming the aqueous solution.

7. A process for manufacturing a laundry care or dish wash formulation, the process comprising: employing the aqueous solutions according to claim 1 in the process.

8. A process comprising transporting the aqueous solution according to claim 1 in a pipe or a container.

9. The aqueous solution according to claim 1, wherein the alkali metal salt of methylglycine diacetic acid is a lithium salt, potassium salt, sodium salt, or a combination thereof.

10. The aqueous solution according to claim 1, wherein the methylglycine diacetic acid is partially or fully neutralized with a respective alkali.

11. The aqueous solution according to claim 1, wherein an average of from 2.7 to 3 COOH groups of the methylglycine diacetic acid is neutralized with an alkali metal.

12. The aqueous solution according to claim 1, wherein the complexing agent (A) is a trisodium salt of the methylglycine diacetic acid.

13. The aqueous solution according to claim 1, comprising from 35 to 50% by weight of the alkali metal salt of methylglycine diacetic acid as the complexing agent (A).

14. The aqueous solution according to claim 1, comprising from 37 to 45% by weight of the alkali metal salt of methylglycine diacetic acid as the complexing agent (A).

15. The aqueous solution according to claim 1, comprising from 45 to 58% by weight of the alkali metal salt of glutamic acid diacetic acid as the complexing agent (A).

16. The aqueous solution according to claim 1, comprising from 46 to 53% by weight of the alkali metal salt of glutamic acid diacetic acid as the complexing agent (A).

17. The aqueous solution according to claim 5, wherein the polyethylene glycol has an average molecular weight M.sub.n of from 600 to 6,000 g/mol.

18. The aqueous solution according to claim 5, comprising from 1 to 20% by weight of the polyethylene glycol (C).

19. The aqueous solution according to claim 1 having a dynamic viscosity of from 80 to 500 mPa.Math.s determined according to DIN 53018-1.2008-09 at 25° C.

20. The aqueous solution according to claim 1 having a Hazen color number of from 15 to 400 determined according to DIN EN 1557:1997-03 at 25° C.

Description

WORKING EXAMPLES

(1) Percentages refer to % by weight unless expressly noted otherwise.

(2) The following substances were used:

(3) Complexing agent (A.1): trisodium salt of MGDA, provided as 40% by weight aqueous solution, pH value: 13 Salt (B.1): sodium acetate, solid Salt (B.2): potassium acetate, solid

(4) I. Manufacture of concentrated aqueous solutions according to the invention

(5) I.1 Manufacture of Aqueous Solutions containing (A.1) and (B.1)

(6) A 25 ml glass bottle with plastic stopper was charged with 22.5 g of the above 40% by weight aqueous solution of (A.1). It was warmed to 75° C. To said solution, 2.5 g of (B.1) were added under repeated shaking. The resulting aqueous solution had a total solids content of 46% by weight. It was a clear solution and did not show any sign of crystallization or precipitation of MGDA even after 30 days at 23° C.

(7) I.2 Manufacture of Aqueous Solutions Containing (A.1) and (B.1)

(8) A 25 ml glass bottle with plastic stopper was charged with 20 g of the above 40% by weight aqueous solution of (A.1). It was warmed to 75° C. To said solution, 5 g of (B.1) were added under repeated shaking. The resulting aqueous solution had a total solids content of 52% by weight. It was a clear solution and did not show any sign of crystallization or precipitation of MGDA even after 30 days at 23° C.

(9) I.3 Manufacture of Aqueous Solutions Containing (A.1) and (B.2)

(10) A 25 ml glass bottle with plastic stopper was charged with 22.5 g of the above 40% by weight aqueous solution of (A.1). It was warmed to 75° C. To said solution, 2.5 g of (B.2) were added under repeated shaking. The resulting aqueous solution had a total solids content of 46% by weight. It was a clear solution and did not show any sign of crystallization or precipitation of MGDA even after 30 days at 23° C.

(11) I.4 Manufacture of Aqueous Solutions Containing (A.1) and (B.2)

(12) A 25 ml glass bottle with plastic stopper was charged with 20 g of the above 40% by weight aqueous solution of (A.1). It was warmed to 75° C. To said solution, 5 g of (B.2) were added under repeated shaking. The resulting aqueous solution had a total solids content of 52% by weight. It was a clear solution and did not show any sign of crystallization or precipitation of MGDA even after 30 days at 23° C.