WO1998026109A1 - The treatment of aluminium surfaces - Google Patents

The treatment of aluminium surfaces Download PDF

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Publication number
WO1998026109A1
WO1998026109A1 PCT/GB1997/003409 GB9703409W WO9826109A1 WO 1998026109 A1 WO1998026109 A1 WO 1998026109A1 GB 9703409 W GB9703409 W GB 9703409W WO 9826109 A1 WO9826109 A1 WO 9826109A1
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WO
WIPO (PCT)
Prior art keywords
composition
functional compound
compound
acid
ions
Prior art date
Application number
PCT/GB1997/003409
Other languages
French (fr)
Inventor
Jim Taylor
Original Assignee
Henkel Kommanditgesellschaft Auf Aktien
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Henkel Kommanditgesellschaft Auf Aktien filed Critical Henkel Kommanditgesellschaft Auf Aktien
Publication of WO1998026109A1 publication Critical patent/WO1998026109A1/en

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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
    • C23C22/06—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 acidic solutions with pH less than 6
    • C23C22/34—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 acidic solutions with pH less than 6 containing fluorides or complex fluorides
    • C23C22/36—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 acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
    • C23C22/361—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 acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing titanium, zirconium or hafnium compounds

Definitions

  • This invention relates to the treatment of aluminium surfaces to reduce roughness.
  • the invention relates to the treatment of aluminium cans during their production to enhance their mobility through the production line.
  • EP-A-293 820 is an example showing how the addition of a lubricant and surface conditioner to the final rinse before drying and painting can increase the mobility of the cans by reducing surface roughness.
  • a disadvantage of this process is that excess lubricant and surface conditioner may have adverse effects on painting and, since the lubricant and surface conditioner is water soluble, any excess cannot be washed off without risking removal of all of it.
  • US-3 332 452 proposes a composition which is added simultaneously with the application of a conversion coating and which enhances mobility of the cans. This has the advantage that, any excess material can be removed by a rinse whilst leaving the mobility aid adhered to the aluminium surface together with the conversion coating. It is therefore an object of the present invention to provide another composition which can be added simultaneously with the conversion coating composition to give mobility, i.e. increased slipperiness, to the surfaces of the cans, particularly during the subsequent painting step.
  • a composition which is soluble in acid conditions and which contains as a mobility aid a bi-functional compound, such as one which contains amine and carboxylate functions, the compound being one which does not alter the water-break free nature of a cleaned aluminium surface.
  • a composition will have an acidic pH, typically from pH 2.0 to 4.0, and more preferably 3.2 to 3.6.
  • the invention therefore also extends to a method of treatment of an aluminium surface with such a composition.
  • Such a composition is preferably added to the conversion coating composition and so a combined composition can comprise a source of zirconium ions, a source of fluoride ions, a source of phosphate ions, and a bi-functional compound such as one containing amine and carboxylate functions, which is soluble in acid conditions and which does not alter the water- - break free nature of a cleaned aluminium surface, the composition having an acidic pH.
  • a typical composition there may be from about 10 to 100 ppm of zirconium ions, from about 20 to 200 ppm of fluoride ions and from about 5 to 100, and more preferably 60 to 80, ppm of phosphate ions.
  • the composition will also contain an acid, e.g. nitric acid, preferably in an amount sufficient to adjust the pH of a working bath using the composition to from 2.0 to 4.0, and more preferably 3.2 to 3.6.
  • the bi-functional compound must be an organic moiety and that this should contain a carbon chain such as an alkyl group of sufficient size to give lubricity to the finished can.
  • the bi-functional compound contains a carbon chain of length C 8 or greater, and more preferably of C 12 or greater. It also appears that the bi-functional compound should contain a group such as an amine group between the alkyl chain and the anionic group, to ensure that the bi-functional compound is soluble under acidic conditions .
  • the bi-functional compound should contain a weakly anionic group such that the compound will precipitate or chemisorb onto the conversion coating given to the can. If the anionic group is too strong, e.g. a sulphonate, this will not aid mobility because it does not appear to precipitate.
  • a weakly acidic group must, however, be soluble in the acid conditions of the composition and so an acid group from a long chain fatty acid cannot be used. The anionic group should therefore be both a weakly acid group and be soluble under acid conditions. Examples of suitable anionic groups are carbonate and phosphate acid ester groups . When a drawn aluminium can is cleaned to removed lubricant and aluminium fines after drawing, the cleaned surface will be water-break free.
  • the bi- functional compound should be chosen such that the cleaned aluminium surface treated with the compound remains water-break free. The bi-functional compound should therefore be water soluble.
  • a suitable bi-functional compound is the alkyl amine carboxylate sold under the trade name Amphionic 32B by Rhone Poulenc .
  • An advantage of the invention is that the bi- functional compound will give increased mobility to the treated can so that there is less risk of jamming during later process steps in the production line, e.g. during removal from the mandril during the conversion coating step. No additional or separate treatment step is required since the bi-functional compound can be applied during the conversion coating step and any excess material can be removed during later washing steps which are conventional. Thus, the bi-functional compound seems to become incorporated into the conversion coating either by adsorption or chemisorption, so that washing will only remove an excess and not remove it completely.
  • the bi-functional compound seem to have no detrimental effect on the conversion coating itself. No significant change is required to the production line, although if desired it is possible for the bi-functional compound to be added in a separate step after the conversion coating.
  • the composition of the conversion coating can be largely conventional and for examples of particular materials, concentrations, types of treatment, etc. reference is directed to US-5 332 452, the whole disclosure of which is deemed to be incorporated herein.
  • the concentration of the conversion coating compounds in the treatment bath can be reduced as compared with the conventional amounts disclosed in US-5 332 452 if one wishes to provide the resulting aluminium cans with mobility and staining of the dome in the underside of the can is not important because the contents of the filled can do not need pasteurisation. Therefore one can reduce the concentration of the conversion coating components to the minimum necessary to hold the bi-functional compound on the surface of the cans .
  • Further advantages of the invention are that the addition of the bi-functional compound to the conversion coating composition does not give sludge or foam in the treatment bath, the composition is tolerant of the presence of residual oils, and the resulting cans are water-break free after their final rinse which enhances drying. Also the compositions appear to impart no adverse taste to the liquid in the final filled cans.
  • the cans treated in this way have a high mobility and when subjected to a conventional slip test, slip angles of 20° are typical and angles of 17° to 18° are often possible.
  • an untreated can would typically have a slip angle of 50° to 60° and there would be no significant improvement in handling of the cans during painting unless the angle was less than 35°. Angles of 20° are therefore regarded as very good.
  • a treatment bath containing the conversion coating composition and bi-functional compound would operate at a temperature of about 35 to 38 °C, preferable about 35°C, a contact time of about 10 to 30 s, preferably about 15 s, a pH of about 3.2 to 3.6, preferably about 3.2, a free acid content of about 0.6 to 1.2%.
  • the bi-functional compound is preferably present in the bath in an amount of from about 0.01 to 0.1%, and more preferably about 0.02 to 0.035%, by weight of the total bath weight.
  • the spraying conditions were: temperature 30°C spray pressure 6psi time 10s.
  • the cans were again subject to a water rinse for 20s followed by a rinse in de-ionised water for 20s.
  • Amphionic 25B were determined. Slip angles above 24° are inconsistent and difficult to measure and so are not reported.

Abstract

Aluminium surfaces are treated to reduce surface roughness by contact with a composition which is soluble in acid conditions and which contains as a mobility aid a bi-functional compound, such as one which contains amine and carboxylate functions, the compound being one which does not alter the water-break free nature of a cleaned aluminium surface. Such a composition will have an acidic pH, typically from pH 2.0 to 4.0, and more preferably 3.2 to 3.6.

Description

THE TREATMENT OF ALUMINIUM SURFACES
This invention relates to the treatment of aluminium surfaces to reduce roughness. In particular the invention relates to the treatment of aluminium cans during their production to enhance their mobility through the production line.
It is known that after aluminium cans have been formed and cleaned, the surface roughness is such that cans are liable to jam in the subsequent steps where they are painted since they tend to jam on the mandrel on which they are held during painting. The faster the production line, the greater is the chance of jamming and so limitation of line speed, and naturally it is desirable to increase the line speed to increase productivity if possible.
EP-A-293 820 is an example showing how the addition of a lubricant and surface conditioner to the final rinse before drying and painting can increase the mobility of the cans by reducing surface roughness. A disadvantage of this process, however, is that excess lubricant and surface conditioner may have adverse effects on painting and, since the lubricant and surface conditioner is water soluble, any excess cannot be washed off without risking removal of all of it.
In an attempt to overcome this, US-3 332 452 proposes a composition which is added simultaneously with the application of a conversion coating and which enhances mobility of the cans. This has the advantage that, any excess material can be removed by a rinse whilst leaving the mobility aid adhered to the aluminium surface together with the conversion coating. It is therefore an object of the present invention to provide another composition which can be added simultaneously with the conversion coating composition to give mobility, i.e. increased slipperiness, to the surfaces of the cans, particularly during the subsequent painting step.
According to the invention there is provided a composition which is soluble in acid conditions and which contains as a mobility aid a bi-functional compound, such as one which contains amine and carboxylate functions, the compound being one which does not alter the water-break free nature of a cleaned aluminium surface. Such a composition will have an acidic pH, typically from pH 2.0 to 4.0, and more preferably 3.2 to 3.6. The invention therefore also extends to a method of treatment of an aluminium surface with such a composition.
Such a composition is preferably added to the conversion coating composition and so a combined composition can comprise a source of zirconium ions, a source of fluoride ions, a source of phosphate ions, and a bi-functional compound such as one containing amine and carboxylate functions, which is soluble in acid conditions and which does not alter the water- - break free nature of a cleaned aluminium surface, the composition having an acidic pH.
In a typical composition there may be from about 10 to 100 ppm of zirconium ions, from about 20 to 200 ppm of fluoride ions and from about 5 to 100, and more preferably 60 to 80, ppm of phosphate ions. The composition will also contain an acid, e.g. nitric acid, preferably in an amount sufficient to adjust the pH of a working bath using the composition to from 2.0 to 4.0, and more preferably 3.2 to 3.6. We believe that the bi-functional compound must be an organic moiety and that this should contain a carbon chain such as an alkyl group of sufficient size to give lubricity to the finished can. In that connection it appears to be desirable that the bi- functional compound contains a carbon chain of length C8 or greater, and more preferably of C12 or greater. It also appears that the bi-functional compound should contain a group such as an amine group between the alkyl chain and the anionic group, to ensure that the bi-functional compound is soluble under acidic conditions .
Further, it appears that the bi-functional compound should contain a weakly anionic group such that the compound will precipitate or chemisorb onto the conversion coating given to the can. If the anionic group is too strong, e.g. a sulphonate, this will not aid mobility because it does not appear to precipitate. A weakly acidic group must, however, be soluble in the acid conditions of the composition and so an acid group from a long chain fatty acid cannot be used. The anionic group should therefore be both a weakly acid group and be soluble under acid conditions. Examples of suitable anionic groups are carbonate and phosphate acid ester groups . When a drawn aluminium can is cleaned to removed lubricant and aluminium fines after drawing, the cleaned surface will be water-break free. The bi- functional compound should be chosen such that the cleaned aluminium surface treated with the compound remains water-break free. The bi-functional compound should therefore be water soluble.
A suitable bi-functional compound is the alkyl amine carboxylate sold under the trade name Amphionic 32B by Rhone Poulenc . An advantage of the invention is that the bi- functional compound will give increased mobility to the treated can so that there is less risk of jamming during later process steps in the production line, e.g. during removal from the mandril during the conversion coating step. No additional or separate treatment step is required since the bi-functional compound can be applied during the conversion coating step and any excess material can be removed during later washing steps which are conventional. Thus, the bi-functional compound seems to become incorporated into the conversion coating either by adsorption or chemisorption, so that washing will only remove an excess and not remove it completely. There is therefore less risk that too much will be present on the can to affect the adhesion of ink during the subsequent painting step. Further the bi-functional compound seem to have no detrimental effect on the conversion coating itself. No significant change is required to the production line, although if desired it is possible for the bi-functional compound to be added in a separate step after the conversion coating. The composition of the conversion coating can be largely conventional and for examples of particular materials, concentrations, types of treatment, etc. reference is directed to US-5 332 452, the whole disclosure of which is deemed to be incorporated herein.
According to one embodiment of the invention, the concentration of the conversion coating compounds in the treatment bath can be reduced as compared with the conventional amounts disclosed in US-5 332 452 if one wishes to provide the resulting aluminium cans with mobility and staining of the dome in the underside of the can is not important because the contents of the filled can do not need pasteurisation. Therefore one can reduce the concentration of the conversion coating components to the minimum necessary to hold the bi-functional compound on the surface of the cans . Further advantages of the invention are that the addition of the bi-functional compound to the conversion coating composition does not give sludge or foam in the treatment bath, the composition is tolerant of the presence of residual oils, and the resulting cans are water-break free after their final rinse which enhances drying. Also the compositions appear to impart no adverse taste to the liquid in the final filled cans.
The cans treated in this way have a high mobility and when subjected to a conventional slip test, slip angles of 20° are typical and angles of 17° to 18° are often possible. In that connection, an untreated can would typically have a slip angle of 50° to 60° and there would be no significant improvement in handling of the cans during painting unless the angle was less than 35°. Angles of 20° are therefore regarded as very good.
According to embodiments of the invention, a treatment bath containing the conversion coating composition and bi-functional compound would operate at a temperature of about 35 to 38 °C, preferable about 35°C, a contact time of about 10 to 30 s, preferably about 15 s, a pH of about 3.2 to 3.6, preferably about 3.2, a free acid content of about 0.6 to 1.2%. The bi-functional compound is preferably present in the bath in an amount of from about 0.01 to 0.1%, and more preferably about 0.02 to 0.035%, by weight of the total bath weight.
The invention will now be illustrated, by way of example, with reference to the following tests taken together with the accompanying figures .
EFFECT OF VARYING APPLICATION CONDITIONS The major variables are : - Application time Temperature
Concentration of the bi-functional compound Concentration of conversion coating composition
Process Conditions
Drawn aluminium cans were sprayed with a cleaning composition consisting of 1% Novaclean 70 (available commercially from the Applicants) plus 15ppm fluoride. The spraying conditions were:
pressure 30psi temperature 51°C time 30s
Thereafter the cans were water rinsed for 20s.
They were then sprayed with a conversion coating composition according to Novamax, treatment NC 9090 (available from the Applicants) and additionally containing as a slip agent 0.035% of the bi-functional compound Amphionic 25B.
The spraying conditions were: temperature 30°C spray pressure 6psi time 10s.
Thereafter, the cans were again subject to a water rinse for 20s followed by a rinse in de-ionised water for 20s.
Temperature
From Figure 1 (Slip v Temperature) it is apparent that an optimum temperature for slip occurs at 35 to 40°C. This is believed to be due to the conflicting effects of the rougher treatment which is formed at high temperatures and the absorbed slip agent
(Amphionic 25B) which is less temperature dependent.
The optimum appears to be at 38°C and this temperature was used in subsequent tests.
Effect of pH and concentration of bi-functional compound (Amphionic 25B The combination of pH and concentration of Amphionic 25B application times was evaluated and the results shown in Figures 2 and 3.
From Figures 2 and 3 the slip at different concentrations of conversion coating composition and
Amphionic 25B were determined. Slip angles above 24° are inconsistent and difficult to measure and so are not reported.
For both 10 and 20 second contact times 0.03 to 0.035% Amphionic 25B and pH of 3.2 to 3.4 give optimum performance. A pH of 3.6 gives acceptable results.

Claims

CLAIMS :
1. A composition which is soluble in acid conditions and which contains as a mobility aid a bi- functional compound, the compound being one which does not alter the water-break free nature of a cleaned aluminium surface.
2. A composition as claimed in Claim 1 in which the bi-functional compound is one which contains amine and carboxylate functions.
3. A composition as claimed in Claim 1 or Claim 2 which has an acidic pH.
4. A composition as claimed in Claim 3 in which the PH is from 2 to 4.
5. A composition as claimed in any preceding claim which is a conversion coating composition and comprises a source of zirconium ions, a source of fluoride ions, a source of phosphate ions, and the bi- functional compound, the composition having an acidic pH.
6. A composition as claimed in Claim 5 which contains from about 10 to 100 ppm of zirconium ions, from about 20 to 200 ppm of fluoride ions and from about 5 to 100, and more preferably 60 to 80, ppm of phosphate ions.
7. A composition as claimed in Claim 5 or Claim 6 which also contains an acid, e.g. nitric acid, in an amount sufficient to adjust the pH of a working bath using the composition to from 2.0 to 4.0, and more preferably 3.2 to 3.6.
8. A composition as claimed in any preceding claim in which the bi-functional compound is an organic moiety containing a carbon chain of length C8 or greater, to give lubricity to the finished can.
9. A composition as claimed in Claim 8 in which bi-functional compound contains an amine group between the alkyl chain and the anionic group, to ensure that the bi-functional compound is soluble under acidic conditions .
10. A composition as claimed in any preceding claim in which the bi-functional compound contains a weakly anionic group, such as a carbonate or phosphate acid ester group, such that the compound will precipitate or chemisorb onto the conversion coating given to the can.
11. A composition as claimed in any preceding claim in which the bi-functional compound is an alkyl amine carboxylate as sold under the trade name Amphionic 32B by Rhone Poulenc .
12. A method for the treatment of an aluminium surface in which the surface is treated with a composition as claimed in any preceding claim.
13. A method as claimed in Claim 12 in which the surface is treated with the composition and at a temperature of about 35 to 38°C, a contact time of about 10 to 30 s, a pH of about 3.2 to 3.6, and a free acid content of about 0.6 to 1.2%.
14. A method as claimed in Claim 12 or Claim 13 in which the bi-functional compound is present in an amount of from about 0.01 to 0.1%, and more preferably about 0.02 to 0.035%, by weight of the total bath weight .
PCT/GB1997/003409 1996-12-11 1997-12-10 The treatment of aluminium surfaces WO1998026109A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9625652.4A GB9625652D0 (en) 1996-12-11 1996-12-11 The treatment of aluminium surfaces
GB9625652.4 1996-12-11

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WO1998026109A1 true WO1998026109A1 (en) 1998-06-18

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3900149A1 (en) * 1988-01-04 1989-07-13 Kao Corp METHOD FOR TREATING THE SURFACE OF A METAL OBJECT AND THE AQUEOUS AQUEOUS SOLUTION THEREFOR
WO1991019828A1 (en) * 1990-06-19 1991-12-26 Henkel Corporation Liquid composition and process for treating aluminium or tin cans to impart corrosion resistance and reduced friction coefficient
US5139586A (en) * 1991-02-11 1992-08-18 Coral International, Inc. Coating composition and method for the treatment of formed metal surfaces
WO1994001517A1 (en) * 1992-07-08 1994-01-20 Henkel Corporation Aqueous lubrication and surface conditioning for formed metal surfaces
WO1995002660A1 (en) * 1993-07-13 1995-01-26 Henkel Corporation Aqueous lubricant and surface conditioner for formed metal surfaces
EP0643127A2 (en) * 1990-03-13 1995-03-15 Henkel Corporation Surface conditioning of formed aluminium objects
EP0645473A1 (en) * 1993-08-31 1995-03-29 Nippon Paint Company Limited Chemical conversion method and surface treatment method for metal can
WO1995033869A1 (en) * 1994-06-03 1995-12-14 Henkel Corporation Composition and method for treating the surface of aluminiferous metals

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3900149A1 (en) * 1988-01-04 1989-07-13 Kao Corp METHOD FOR TREATING THE SURFACE OF A METAL OBJECT AND THE AQUEOUS AQUEOUS SOLUTION THEREFOR
EP0643127A2 (en) * 1990-03-13 1995-03-15 Henkel Corporation Surface conditioning of formed aluminium objects
WO1991019828A1 (en) * 1990-06-19 1991-12-26 Henkel Corporation Liquid composition and process for treating aluminium or tin cans to impart corrosion resistance and reduced friction coefficient
US5139586A (en) * 1991-02-11 1992-08-18 Coral International, Inc. Coating composition and method for the treatment of formed metal surfaces
US5332452A (en) * 1991-02-11 1994-07-26 Coral International, Inc. Coating composition and method for the treatment of formed metal surfaces
WO1994001517A1 (en) * 1992-07-08 1994-01-20 Henkel Corporation Aqueous lubrication and surface conditioning for formed metal surfaces
WO1995002660A1 (en) * 1993-07-13 1995-01-26 Henkel Corporation Aqueous lubricant and surface conditioner for formed metal surfaces
EP0645473A1 (en) * 1993-08-31 1995-03-29 Nippon Paint Company Limited Chemical conversion method and surface treatment method for metal can
WO1995033869A1 (en) * 1994-06-03 1995-12-14 Henkel Corporation Composition and method for treating the surface of aluminiferous metals

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