Sodium percarbonate stabilized by coating

• US 5,346,680 A
• Filed: 10/18/1993
• Issued: 09/13/1994
• Est. Priority Date: 10/16/1992
• Status: Expired due to Term

• Current Assignee: Solvay Interox GmbH (Solvac SA)
• Original Assignee: Solvay Interox GmbH (Solvac SA)
• Inventors: Soentgerath, Alfred, Hecken, Gerd, Doetsch, Werner, Roesler, Richard
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US08/137,251
• Time in Patent Office: 330 Days
• Field of Search: 423/274, 423/415.2
• US Class Current: 423/274
• CPC Class Codes: C01B 15/106 Stabilisation of the solid compounds, subsequent to the preparation or to the crystallisation, by additives or by coating
• CPC Class Codes: C11D 17/0039 Coated compositions or coated components in the compositions, (micro)capsules
• CPC Class Codes: C11D 3/3942 Inorganic per-compounds C11D3/3902 takes precedence

Abstract

Sodium percarbonate particles stabilized by being coated with a solid coating material which contains a mixture of sodium carbonate and sodium chloride, optionally together with one or more auxiliary agents used in the manufacture of sodium percarbonate.

Claims

1. Sodium percarbonate particles coated with a solid inorganic coating material wherein the coating material comprises a mixture of sodium carbonate and sodium chloride.

2. Sodium percarbonate particles according to claim 1, wherein the coating material comprises at least 1 wt-% of the coated sodium percarbonate particles.

3. Sodium percarbonate particles according to claim 2, wherein the coating material comprises from 2 to 12 wt-% of the coated sodium percarbonate particles.

4. Sodium percarbonate particles according to claim 3, wherein the coating material comprises from 3 to 7 wt-% of the coated sodium percarbonate particles.

5. Coated sodium percarbonate particles according to claim 1, wherein at least 80 wt-% of the coating material is comprised of said mixture of sodium carbonate and sodium chloride.

6. Coated sodium percarbonate particles according to claim 1, wherein said mixture comprises a weight ratio of sodium carbonate to sodium chloride in the range from 1:

5 to 3;

1.

7. Coated sodium percarbonate particles according to claim 6, wherein said mixture comprises a weight ratio of sodium carbonate to sodium chloride in the range from 1:

4 to 2;

1.

8. Sodium percarbonate particles according to claim 1, wherein said coating further comprises at least one auxiliary agent selected from the group consisting of sodium polyphosphates, sodium polycarboxylates, sodium silicates, phosphonic acids and salts thereof, and magnesium sulfate.

9. Coated sodium percarbonate particles according to claim 8, wherein the coating material contains up to a maximum of 20 wt-% of said auxiliary agents.

10. A process for producing stabilized sodium percarbonate particles coated with a solid inorganic coating material, said process comprising coating particles of sodium percarbonate with a coating material which comprises a mixture of sodium carbonate and sodium chloride by treating the particles to be coated with an aqueous liquid composition containing said coating material and thereafter drying the treated particles.

11. A process according to claim 10, wherein said aqueous liquid composition is an aqueous solution of said coating material.

12. A process according to claim 10, wherein said aqueous liquid composition is an aqueous suspension of said coating material.

13. A process according to claim 10, wherein said coating material further comprises at least one auxiliary agent selected from the group consisting of sodium polyphosphates, sodium polycarboxylates, sodium silicates, phosphonic acids and salts thereof, and magnesium sulfate.

14. A process according to claim 10, wherein said aqueous liquid composition has a solids content of at least 20 wt-%.

15. A process according to claim 14, wherein said aqueous liquid composition has a solids content of from 25 to 45 wt-%.

16. A process according to claim 15, wherein said aqueous liquid composition has a solids content of from 30 to 40 wt-%.

17. A process according to claim 10, wherein in said drying step the treated particles are dried to a residual water content of less than 1.5 wt-%.

18. A process according to claim 17, wherein in said drying step the treated particles are dried to a residual water content of less than 0.8 wt-%.

19. A process according to claim 10, wherein the particles of sodium percarbonate are coated with a sufficient amount of coating material such that the coating material comprises at least 1 wt-% of the coated particles.

20. A process according to claim 19, wherein the particles of sodium percarbonate are coated with a sufficient amount of coating material such that the coating material comprises from 2 to 12 wt-% of the coated particles.

21. A process according to claim 20, wherein the particles of sodium percarbonate are coated with a sufficient amount of coating material such that the coating material comprises from 3 to 7 wt-% of the coated particles.

22. A process according to claim 10, wherein at least 80 wt-% of the coating material is comprised of said mixture of sodium carbonate and sodium chloride.

23. A process according to claim 10, wherein said mixture comprises a weight ratio of sodium carbonate to sodium chloride in the range from 1:

5 to 3;

1.

24. A process according to claim 23, wherein said mixture comprises a weight ratio of sodium carbonate to sodium chloride in the range from 1:

4 to 2;

1.

25. A process according to claim 10, wherein the coating material comprises at least 80 wt-% of said mixture of sodium carbonate and sodium chloride and up to a maximum of 20 wt-% of at least one auxiliary agent selected from the group consisting of sodium polyphosphates, sodium polycarboxylates, sodium silicates, phosphonic acids and salts thereof, and magnesium sulfate.

26. A process according to claim 10, wherein said aqueous liquid composition comprises a mother liquor obtained from the manufacture of sodium percarbonate by reacting an aqueous solution or suspension of sodium carbonate with a hydrogen peroxide solution in the presence of sufficient sodium chloride for salting out.

27. A process according to claim 26, wherein said mother liquor is obtained from the manufacture of sodium percarbonate by reacting aqueous sodium carbonate with a hydrogen peroxide solution in the presence of sodium chloride and at least one auxiliary agent selected from the group consisting of sodium polyphosphates, sodium polycarboxylates, sodium silicates, phosphonic acids and salts thereof, and magnesium sulfate.

28. A process according to claim 26, wherein said mother liquor contains up to a maximum of 2 wt-% active oxygen.

29. A process according to claim 26, wherein said aqueous liquid composition is adjusted to have a solids content of at least 20 wt-% by adding sodium carbonate to said mother liquor.

30. A process according to claim 29, wherein said aqueous liquid composition is adjusted to have a solids content of at least 20 wt-% by adding to said mother liquor sodium carbonate and at least one auxiliary agent selected from the group consisting of sodium polyphosphates, sodium polycarboxylates, sodium silicates, phosphonic acids and salts thereof, and magnesium sulfate.

31. A process according to claim 29, wherein said aqueous liquid composition is adjusted to have a solids content of from 25 to 45 wt-%.

32. A process according to claim 31, wherein said aqueous liquid composition is adjusted to have a solids content of from 30 to 40 wt-%.