GB2298870A - Chromium-free electrolytic passivation treatment of tinplate using aqueous solutions of Group IV metal compounds - Google Patents
Chromium-free electrolytic passivation treatment of tinplate using aqueous solutions of Group IV metal compounds Download PDFInfo
- Publication number
- GB2298870A GB2298870A GB9505041A GB9505041A GB2298870A GB 2298870 A GB2298870 A GB 2298870A GB 9505041 A GB9505041 A GB 9505041A GB 9505041 A GB9505041 A GB 9505041A GB 2298870 A GB2298870 A GB 2298870A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tinplate
- sulphate
- chromium
- passivation
- titanium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/48—After-treatment of electroplated surfaces
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D9/00—Electrolytic coating other than with metals
- C25D9/04—Electrolytic coating other than with metals with inorganic materials
- C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
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- Chemical & Material Sciences (AREA)
- Metallurgy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
- Mechanical Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
- Electrodes Of Semiconductors (AREA)
- Chemically Coating (AREA)
- Printing Plates And Materials Therefor (AREA)
- Photoreceptors In Electrophotography (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
A chromium free passivation film for tinplate. The film is produced electrolytically by immersing tinplate in an aqueous solution of a soluble compound selected from potassium titanium oxalate, titanium sulphate and zirconium sulphate. The film so produced has sulphide stain resistance comparable to that produced by conventional chromium bearing passivating solutions. <IMAGE>
Description
?X 1 PASSIVATION TREATMWM OF TINPLATE 2298870 This invention relates to
passivation treatments for applying chromium- free passivation films to tinplate.
Passivation is a treatment in which chemically active surfaces of tinplate are coated with impervious films of a passive material by anodic or cathodic polarisation significantly to reduce the active state of such surfaces. It is of course extremely important that tinplate used in the canning industry is chemically inactive. In commercial production, strips of blackplate are passed continuously through a series of treatment tanks to clean, plate and chemically treat the plated material prior to use. Conventionally, passivation fluids are chromium-based aqueous solutions, typically sodium dichromate. Like many chromium-based solutions, sodium dichromate is a hazardous fluid which represents a potential health risk to line operatives and is environmentally unfriendly. There is therefore on both health and environmental grounds an increasing need to develop chromium-free passivation treatments.
'I 2 Commercially any such treatment must meet a range of performance criteria equivalent to or better than those of chromium based passivation treatments. Also, any such treatment should be capable of application under tinning line conditions similar to those used for chromate-based treatments, these including a typical treatment time of approximately one second.
The present invention sets out to provide a chromiumfree passivation treatment which meets these and other criteria.
In one aspect, the invention provides a chromium free passivation film for tinplate, the film being produced electrolytically by immersing tinplate in an aqueous solution of a soluble compound of an element taken from Group 4a of the Periodic Table and the film so produced having sulphide stain resistance comparable to that produced by conventional chromium bearing passivating solutions.
Preferred compounds are potassium titanium oxalate, titanium sulphate and zirconium sulphate.
According to the present invention in another aspect there is provided a passivation treatment in which the passivating solution is an aqueous solution of a compound selected from potassium titanium oxalate, titanium sulphate and zirconium sulphate.
Preferred concentrations of titanium sulphate in solution are from 15 to 30 gms per litre.
Preferred concentrations of potassium titanium oxalate 3 in solution are from 5 to 20 gms per litre.
Preferred concentrations of zirconium sulphate in solution are from 10 to 30 gms per litre.
In a further aspect the invention provides a passivation treatment for tinplate in which the passivating element is either titanium or zirconium.
The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which:- Figure 1 is a schematic diagram of a plating line for conducting passivation treatments in accordance with the invention; and Figure 2 is a graph comparing depth profile analyses of passivating elements in accordance with the invention with the conventional passivating element sodium dichromate.
The plating line illustrated in Figure 1 comprises a plurality of guide rollers 1 for transporting a strip of blackplate 2 continuously from a coiled roll 3 to an exit coil 4 via a multiplicity of tanks. These tanks include a cleaning tank 5, rinsing tanks 6, a pickling tank 7, a plating tank 8 and an electrolytic chemical treating tank 9. Towards the centre of the plating line is a reflow 11 to each side of which are positioned a drag-out bath 12 and quenching bath 13. A welding station 15 is positioned between the roll 3 and the entrance to the plating line. The plating line illustrated is generally conventional.
In use, strip is passed continuously through the 4 plating line with a thin passivating film being applied to both sides of the tinplate as it passes through the tank 9. The line speed is typically 300-350 metres per minute with a treatment dwell time in tank 9 of one second. Static electrodes are provided in the tank 9, deposition of the passivating film being achieved by cathodic reaction. The width.of the strip 2 is typically 1 metre and above and the treatment temperature is typically 650C.
Hitherto the passivating solution present in the treatment tank 9 has been chromium-based and in particular sodium dichromate. In the present invention a chromiumfree passivating solution is employed, this being selected from aqueous solutions of zirconium sulphate, potassium titanium oxalate and titanium sulphate.
For zirconium sulphate a solution concentration in the range 10 to 30 gms per litre is preferred, a typical concentration being 21 gms per litre.
For potassium titanium oxalate a solution concentration in the range 5 to 20 gms per litre--is preferred, a typical concentration being 14 gms per litre.
For titanium sulphate a solution concentration in the range 15 to 30 gms. per litre is preferred, a typical concentration being 21 gms per litre.
Thus, the passivating element is either titanium or zirconium.
Depth profile analyses of each of the passivating elements are shown in the graph of Figure 2. It was found that all three chromium-free treatments produced thicker oxide levels than a conventional chromium-based passivation treatment.
By way of example, aqueous solutions of titanium sulphate in a concentration of 21 gm/litre, potassium titanium oxalate in a concentration of 14 gm/litre and zirconium sulphate in a concentration of 21 gm/litre were prepared. These solutions were in turn used in trial passivation treatments of tinplate, the bath temperature, cathodic application and pass time being respectively 650C, coulomb density 6.4 c/dm2 and one second. Strip speed for each trial was assumed as 180 metres/minute and the pass time through the passivation bath was one second.
Sulphide stain resistance of all three treatments was found marginally to be comparable to that of a treatment using sodium dichromate.
No discolouration of the tinplate occurred.
The weldability range of tinplate treated in accordance with the invention was generally higher than for that treated using sodium dichromate. No abnormal weld features were observed.
After two months storage, tinplate treated in accordance with the invention exhibited less passive film damage than tinplate treated using sodium dichromate.
Tinplate produced by all these chromium-free treatments exhibited improved adhesion when compared with tinplate treated with sodium dichromate.
It was found that surface concentrations of titanium and zirconium were lower than for chromium.
6 All three treatments produced thicker oxide levels than that produced with sodium dichromate.
In summary, the trials show that treatments in accordance with the invention provide effective alternatives to sodium dichromate passivation and can be applied using current tinplate technology; that potassium titanium oxalate, titanium sulphate and zirconium sulphate based treatments meet requirements for alternative chromium-free passivation for tinplate; that it is possible to weld tinplate passivated in accordance with the invention at commercial settings; that treatments in accordance with the invention give improved lacquer adhesion compared to chromium-based treatments; that passive films produced in accordance with the invention provide more abrasion resistance than passive films produced using sodium dichromate; that treatments in accordance with the invention provide treatments of comparable performance to chromium-based treatments; that surface chemistry for treatments in accordance with the invention exhibited reduced amounts of passive film elements compared to chromium-based treatments; and that total oxide film thickness of tinplate treated in accordance with the invention were greater than that produced by chromium-based treatments.
It will be appreciated that the foregoing is merely exemplary of in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.
Claims (1)
- 7 A chromium free passivation film for tinplate, the film being produced electrolytically by immersing tinplate in an aqueous solution of a soluble compound of an element taken f rom Group 4a of the Periodic Table and the film so produced having sulphide stain resistance comparable to that produced by conventional chromium bearing passivating solutions.2. A passivation f ilm as claimed in claim 1 wherein the soluble compound is one of potassium titanium oxalate, titanium sulphate and zirconium sulphate.A passivation treatment in which the passivating solution is an aqueous solution of a compound selected from potassium titanium oxalate, titanium sulphate and zirconium sulphate.4. A passivation treatment as claimed in claim 3 wherein the concentration of titanium sulphate in solution is in the range from 15 to 30 gms per litre.5. A passivation treatment as claimed in claim 3 wherein the concentration of potassium titanium oxalate in solution is in the range from 5 to 20 gms per litre.8 6. A passivation treatment as claimed in claim 3 wherein the concentration of zirconium sulphate in solution is in the range from 10 to 30 gas per litre.A passivation treatment for tinplate in which the passivating element is either titanium or zirconium.8. A chromium free passivation film as herein described and as described with reference to Figures 1 and 2 of the accompanying diagrammatic drawings.A passivation treatment as herein described and as described with reference to Figures 1 and 2 of the accompanying diagrammatic drawings.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9505041A GB2298870B (en) | 1995-03-13 | 1995-03-13 | Passivation treatment of tinplate |
EP96301491A EP0732425B1 (en) | 1995-03-13 | 1996-03-05 | Passivation treatment of tinplate |
AT96301491T ATE243269T1 (en) | 1995-03-13 | 1996-03-05 | PASSIVATION OF TIN-PLATED SHEET |
DE69628689T DE69628689T2 (en) | 1995-03-13 | 1996-03-05 | Passivation of tinned sheets |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9505041A GB2298870B (en) | 1995-03-13 | 1995-03-13 | Passivation treatment of tinplate |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9505041D0 GB9505041D0 (en) | 1995-05-03 |
GB2298870A true GB2298870A (en) | 1996-09-18 |
GB2298870B GB2298870B (en) | 1998-09-30 |
Family
ID=10771124
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9505041A Expired - Fee Related GB2298870B (en) | 1995-03-13 | 1995-03-13 | Passivation treatment of tinplate |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0732425B1 (en) |
AT (1) | ATE243269T1 (en) |
DE (1) | DE69628689T2 (en) |
GB (1) | GB2298870B (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10022074A1 (en) * | 2000-05-06 | 2001-11-08 | Henkel Kgaa | Protective or priming layer for sheet metal, comprises inorganic compound of different metal with low phosphate ion content, electrodeposited from solution |
IT1316032B1 (en) * | 2000-12-19 | 2003-03-26 | Ct Sviluppo Materiali Spa | PROCEDURE FOR THE PASSIVATION OF STAINLESS STEEL BAND WITH CHROMIUM-FREE PASSIVATION FILM. |
EP1893791A2 (en) * | 2005-06-22 | 2008-03-05 | Henkel Kommanditgesellschaft Auf Aktien | ELECTRODEPOSITION MATERIAL, PROCESS FOR PROVIDING A CORROSION-PROTECTIVE LAYER OF TiO2 ON AN ELECTRICALLY CONDUCTIVE SUBSTRATE AND METAL SUBSTRATE COATED WITH A LAYER OF TiO2 |
EP2180084B1 (en) * | 2007-08-23 | 2018-10-10 | Nippon Steel & Sumitomo Metal Corporation | Environmentally friendly steel sheet for container material, process for producing the same, and environmentally friendly laminated steel sheet for container material and precoated steel sheet for container material each produced from that steel sheet |
EP3626862B1 (en) * | 2018-09-24 | 2021-03-10 | Tenova S.p.A. | Passivation process of a steel tinplate |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5468734A (en) * | 1977-11-11 | 1979-06-02 | Nippon Packaging Kk | Surface treatment of tin plated steel plate and can |
CA1162504A (en) * | 1980-11-25 | 1984-02-21 | Mobuyuki Oda | Treating tin plated steel sheet with composition containing titanium or zirconium compounds |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5993886A (en) * | 1982-11-17 | 1984-05-30 | Katayama Chem Works Co Ltd | Anticorrosive for metal |
-
1995
- 1995-03-13 GB GB9505041A patent/GB2298870B/en not_active Expired - Fee Related
-
1996
- 1996-03-05 DE DE69628689T patent/DE69628689T2/en not_active Expired - Lifetime
- 1996-03-05 EP EP96301491A patent/EP0732425B1/en not_active Expired - Lifetime
- 1996-03-05 AT AT96301491T patent/ATE243269T1/en active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5468734A (en) * | 1977-11-11 | 1979-06-02 | Nippon Packaging Kk | Surface treatment of tin plated steel plate and can |
CA1162504A (en) * | 1980-11-25 | 1984-02-21 | Mobuyuki Oda | Treating tin plated steel sheet with composition containing titanium or zirconium compounds |
Non-Patent Citations (2)
Title |
---|
WPI Abstract No:79-51575B/28 & JP 54 068 733 A * |
WPI Abstract No:79-51576B/28 & JP 54 068 734 A * |
Also Published As
Publication number | Publication date |
---|---|
GB9505041D0 (en) | 1995-05-03 |
ATE243269T1 (en) | 2003-07-15 |
EP0732425A1 (en) | 1996-09-18 |
EP0732425B1 (en) | 2003-06-18 |
GB2298870B (en) | 1998-09-30 |
DE69628689D1 (en) | 2003-07-24 |
DE69628689T2 (en) | 2004-04-29 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20030313 |