Method of surface treatment of tin plated cans and tin plated steel sheets

• US 4,339,310 A
• Filed: 11/26/1980
• Issued: 07/13/1982
• Est. Priority Date: 11/25/1980
• Status: Expired due to Term

• Current Assignee: Occidental Chemical Corporation (Occidental Petroleum Corporation)
• Original Assignee: Hooker Chemicals & Plastics Corp. (Occidental Petroleum Corporation)
• Inventors: Oda, Nobuyuki, Terada, Haruyoshi
• Primary Examiner(s): Gantz, Delbert E.
• Assistant Examiner(s): LEADER, WILLIAM T
• Application Number:
  US06/210,706
• Time in Patent Office: 594 Days
• Field of Search: 148/6.15 R, 106/14.12, 204/38 R, 204/42, 204/56 R
• US Class Current: 205/199
• CPC Class Codes: C23C 22/07 containing phosphates
• CPC Class Codes: C23C 22/37 containing also hexavalent chromium compounds
• CPC Class Codes: C23C 22/68 using aqueous solutions with pH between 6 and 8
• CPC Class Codes: C25D 9/06 by anodic processes

Abstract

An aqueous chromium-free composition is useful for imparting a corrosion resistance paintable coating to a tin surface. The composition contains a titanium or zirconium compound, a pyrazole derivative, a myoinositol phosphate ester and a silicon compound. The surface is either chemically coated via contact with the composition or electrolytically coated via immersion in the composition.

Claims

1. A chromium-free aqueous composition, comprising:

(a) at least one soluble compound selected from the group consisting of titanium and zirconium compounds;

(b) at least one pyrazole compound of the formula;

##STR5## wherein X, Y and Z are independently selected from the group consisting of hydrogen atom, hydroxyl group, alkyl group of up to 5 carbon atoms, amino group and nitro group;

(c) at least one myoinositol phosphate ester having 2-6 phosphate groups per molecule; and

(d) at least one silicon compound;

said composition exhibiting a pH value in the range of from 1.0 to 10.0.

2. The composition of claim 1 wherein the concentration of the components is:

(a) 0.001-10 g/l (calculated as Zr or Ti)

(b) 0.01-20 g/l

(c) 0.005-50 g/l (calculated as phosphoric acid)

(d) 0.001-10 g/l (calculated as silicon)

3. The composition of claim 2 wherein the concentration of the components is:

(a) 0.01-1.0 g/l (calculated as Zr or Ti)

(b) 0.1-5 g/l

(c) 0.01-10 g/l (calculated as phosphoric acid)

(d) 0.005-1 g/l (calculated as silicon)

4. The composition of claim 1 additionally containing an oxidizing or reducing agent.

5. A process for forming a coating on a tin surface comprising contacting the surface with the composition of claim 1 at a temperature of 10°

-90°

C. for a time sufficient to form the coating.

6. The process of claim 5 wherein the surface is immersed in the composition and electrolyzed with the surface as anode.

7. The process of claim 6 wherein the surface is subjected to a current density of 0.1-50 A/dm² for 0.1 second to 2 minutes.

8. The process of claim 5, 6, or 7 wherein the coated surface is painted.