Anti-tarnish aqueous treatment

• US 20050148480A1
• Filed: 02/23/2005
• Published: 07/07/2005
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: For Your Ease Only
• Original Assignee: For Your Ease Only
• Inventors: Croce, Scott M.
• Granted Patent: US 7,037,379 B2
• Time in Patent Office: Days
• US Class Current: 510/201
• CPC Class Codes: C23G 1/065 sulfur-containing compounds
• CPC Class Codes: C23G 1/10 Other heavy metals

Abstract

An aqueous solution that has the capacity for removing tarnish and other soil from copper, silver, gold and other noble metals and alloys thereof comprises an acid, thiourea and a transition metal salt. The aqueous material can be used to treat the surfaces of such articles for the purpose of removing tarnish. Such tarnish is removed by the composition and the composition treats the metal surface to retard the re-appearance of tarnish contaminants.

Claims

1. An aqueous metal cleaning composition comprising:

(a) a major proportion of water;

(b) sufficient aqueous soluble acid to obtain a pH less than 6;

(c) about 5 to 25 wt % of thiourea; and

(d) about 2 to 30 wt % of a transition metal salt.

2. The composition of claim 1 wherein the transition metal salt comprises a Group VI(b) metal salt, a Group VIII metal salt or mixtures thereof.

3. The composition of claim 1 wherein the transition metal salt comprises a blend of a first transition metal salt and a blend of a second transition metal salt.

4. The composition of claim 3 wherein the first transition metal salt comprises a Group VI(b) salt and the second transition metal salt comprises a Group VIII(9) salt.

5. The composition of claim 2 wherein the acid comprises nitric acid or hydrochloric acid and transition metal salt comprises a mixed transition metal salt comprising a nitrate or chloride.

6. The composition of claim 1 wherein the acid is nitric acid and the concentration of nitric acid is about 10 to about 60 wt %.

7. The composition of claim 1 wherein the concentration of thiourea is about 10 to about 25 wt %.

8. The composition of claim 1 wherein the composition comprises an effective amount of a solvent.

9. The composition of claim 1 wherein the composition comprises and effective amount of a surface active agent for wetting or soil removal.

10. An aqueous metal cleaning composition comprising:

(a) a major proportion of water;

(b) sufficient nitric acid to obtain a pH less than 6;

(c) about 5 to 25 wt % of thiourea; and

(d) about 2 to 30 wt % of a transition metal salt selected from the group consisting of cobalt salts, rhenium salts, iridium salts or mixtures thereof; and

(e) about 2 to 30 wt % of a transition metal salt selected from the group consisting of chromium salts, molybdenum salts, tungsten salts or mixtures thereof.

11. The composition of claim 10 wherein the acid is present in the concentration of about 10 to 60 wt %.

12. The composition of claim 10 wherein the thiourea is present in the concentration of about 5 to 25 wt %.

13. The composition of claim 10 wherein the composition comprises about 2 to 15 wt % of a chromium nitrate salt and about 2 to 15 wt % of a cobalt nitrate salt.

14. The composition of claim 10 wherein the acid is a mixed acid.

15-19. -19. (canceled)

20. An aqueous metal cleaning concentrate composition comprising:

(a) a major proportion of water;

(b) greater than 40 wt.-% aqueous soluble acid;

(c) greater than 25 wt % of thiourea; and

(d) greater than 25 wt % of transition metal salt.

21. The composition of claim 20 wherein the transition metal salt comprises a Group VI(b) metal salt, a Group VIII metal salt or mixtures thereof.

22. The composition of claim 20 wherein the transition metal salt comprises a blend of a first transition metal salt and a blend of a second transition metal salt.

23. The composition of claim 22 wherein the first transition metal salt comprises a Group VI(b) salt and the second transition metal salt comprises a Group VIII(9).

24. The composition of claim 20 wherein the acid comprises nitric acid, hydrochloric acid and transition metal salt comprises a transition metal nitrate.

25. The composition of claim 20 wherein the composition comprises an effective amount of a solvent.

26. The composition of claim 20 wherein the composition comprises and effective amount of a surface active agent for wetting or soil removal.

27. An aqueous metal cleaning composition prepared by mixing:

(a) a major proportion of water;

(b) sufficient water soluble acid to obtain a pH less than 6;

(c) about 5 to 25 wt % of thiourea; and

(d) about 2 to 30 wt % of a transition metal salt.