Continuous electrolytical treatment of aluminum or its alloys

Abstract

A process for electrolytically treating aluminum or its alloys in the form of a strip, wire or foil material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell through which a direct current, alternating current or AC-superimposed direct current is caused to flow and an electrolytic coloring cell through which an alternating current or AC-superimposed direct current is caused to flow and carrying out electrolysis in both said cells to anodize and color the material in a continuous manner.

Description

This is a reissue application of U.S. Pat. No. 4,014,758, which matured from Ser. No. 570,376, filed Apr. 22, 1975. two anodic oxidation treatment cells 1₂ and 2₂1 a negatively charging cell 1₂ and an anodic oxidation treatment cell 1₂1 (which contain an electrolytic solution having the same composition as that of the solution in the electrolytic cell 1), and an alternating current voltage is applied between the electrode plate 2₂ and an electrode plate 5₂ disposed within an electrolytic coloring cell 4₂ (which contains an electrolytic solution having the same composition as that of the solution in the electrolytic cell 4).

A strip 6 wound on an uncoiler (not shown) is unwound and is subjected to the afore-mentioned pretreatment. The strip thus pretreated is passed through the electrolytic cell 1₂ at any appropriate rate to charge it negatively and then passed through the electrolytic cell 1₂1 (both the electrolytic cells 1₂ and 1₁2 containing an electrolytic solution having the same composition as that of the solution in the electrolytic cell 1) to anodize it under the same anodizing conditions as those in the electrolytic cell 1. Then, the anodized strip is subjected to an electrolytic treatment under the same coloring conditions as those in the electrolytic cell 4 while being passed through the electrolytic cell 4₂. Results similar to those of the Examples using the apparatus shown in FIG. 1 are obtained. Thereafter, the colored strip is washed with water and wound up on a recoiler (now shown).

In still another example using the apparatus shown in FIG. 4, an anodic oxidation treatment cell 1₃ (which contains an electrolytic solution having the same composition as that of the solution in the cell 1) is divided into two compartments 9 and 9₁ i.e. a negatively charging compartment 9 and an anodizing compartment 9₁, by means of a diaphragm 8 with a slit 7. A direct current voltage is applied between electrode plates 2₃ and 2₃1 which are respectively disposed within the compartments 9 and 9₁, and an alternating current voltage is applied between the electrode plate 2₃ and an electrode plate 5₃ disposed within an electrolytic coloring cell 4₃ (which contains an electrolytic solution having the same composition as that of the solution in the cell 4).

A strip 6 wound on an uncoiler (not shown) is unwound and is then subjected to the pretreatment described in Example 1. The pretreated strip is passed through the compartment 9 in the electrolytic cell 1₃ (the electrode plates 2₃ and 2₃1 being made of aluminum) at any appropriate rate to charge it negatively and subsequently passed through the compartment 9₁ to anodize it under the same anodizing conditions as those in the cell 1. The anodized strip is then passed through the electrolytic cell 4₃ to color it under the same coloring conditions as those in the electrolytic cell 4. Results similar to those in Example 4 are obtained. The colored product is washed with water and wound up on a recoiler (not shown).

In a further example using the apparatus shown in FIG. 5, an anodic oxidation treatment cell 1₄ is divided into two compartments 9₂ and 9₂1 i.e. a negatively charging compartment 9₂ and an anodizing compartment 9₂1, by means of a diaphragm 8₁ with a slit 7₁. An AC-superimposed direct current from its sources G is applied between electrode plates 2₄ and 2₄1 which are each disposed within the compartments 9₂ and 9₂1 and between the electrode plate 2₄ and an electrode plate 5₄ disposed within an electrolytic coloring cell 4₄.

A strip 6 wound on an uncoiler (not shown) is unwound and is subjected to the pretreatment as described in Example .Badd.1. The pretreated strip is passed through the compartment 9₂ in the electrolytic cell 1₄ at any appropriate rate to charge it negatively and subsequently passed through the compartment 9₂1 to anodize it. The anodized strip is then passed through the electrolytic cell 4₄ to color it. The colored strip is washed with water and wound up on a recoiler (not shown).

EXAMPLE 5

In this example the apparatus shown in FIG. 5 was used. An aluminum alloy (1050 - H24) was anodized at a rate of 3 m/min. in an aqueous solution containing 100 g/l oxalic acid in the electrolytic cell 1₄ including the electrode plates 2₄ and 2₄1 made of aluminum. The temperature of the solution was 30°C and the superposed current voltage applied was composed of an alternative current voltage of 20 V and a direct current voltage of 5 V. The anodized alloy was electrolytically colored in the electrolytic cell 4₄ including an electrode plate 5₄ made of carbon using an aqueous solution containing 5 g/l stannous sulfate, 10 g/l sulfuric acid, and 5 g/l phenolsulfonic acid. The alternating current voltage used was 25 V. When treating times of 1, 11/2 and 3 minutes were used, a product having an anodic oxide film of a thickness of 5μ obtained was olive, amber and bronze in color, respectively.

Each colored strip was then washed with water and wound up on a recoiler with or without a sealing treatment depending on the end use.

Before winding up by a recoiler, the strip product may be coated with a thermosetting resin by means of various coating methods such as dipping, electrodeposition, blowing, electrostatic coating, power coating and roll coater coating and dried and baked to give a colored aluminum material having an excellent corrosion resistance and weather resistance. As a paint, a powder paint drying at normal temperature may be used.

The aluminum material produced according to the process of the present invention is processed into building materials such as a lengthy spandrel, panel and ceiling material for use in an outer or inner covering of a building, shop or house. The aluminum material may be laminated with a refractory board, iron plate or veneer plate to produce a composite material usable as a quality wall material. Further, the aluminum material may be used as a name plate and a decorative cover of electrical instruments.

Claims

1. A process for electrolytically treating aluminum or its alloy in the form of a strip, wire or foil material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell and an electrolytic coloring cell to carry out electrolysis in said cells to anodize and color the material in a continuous manner, characterized in that just prior to the anodizing stage, a circuit is formed by commonly connecting to the aluminum material a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the anodizing cell and said power source for electrolytically coloring being further connected to the electrolytic coloring cell; said power source for anodizing being DC and the power source for electrolytically coloring being AC, or the power source for both of them being a single AC-superimposed direct current, whereby a current having an alternating wave form rich in positive component is supplied to the electrode of the electrolytic coloring cell.

2. The process according to claim 1 wherein the electrolytic coloring is carried out in a solution containing a tin salt.

3. The process according to claim 1 wherein the electrolytic coloring is effected in a solution containing a tin salt and at least one member selected from the group consisting of nickel salts,

cobalt salts, iron salts, magnesium salts, and zinc salts.

4. The process according to claim 1 wherein the electrolytic coloring is carried out in a solution containing at least one member selected from the group consisting of copper salts, selenium salts, manganese salts, and zirconium salts.

5. The process according to claim 1 wherein a direct current voltage is applied between an electric power supply element outside the anodic oxidation treatment cell and an electrode plate within said cell and an alternating current voltage is applied between said element and an electrode plate within the electrolytic coloring cell.

6. The process according to claim 1 wherein two anodic oxidation treatment cells are used, a direct current voltage being applied between electrode plates contained respectively in said two cells, an alternating current voltage being applied between one of said plates and an electrode plate in the electrolytic coloring cell.

7. The process according to claim 1 wherein the anodic oxidation treatment cell is divided into two compartments by a diaphragm with a slit, a direct current voltage being applied between electrode plates contained in said compartments, an alternating current voltage being applied between one of said plates and an electrode plate in the coloring cell.

8. The process according to claim 1 wherein the anodic oxidation treatment cell is divided into two compartments by a diaphragm with a slit, an AC-superimposed direct current voltage being applied between electrode plates respectively in said compartments and an electrode plate in the coloring cell.

9. A process according to claim 1, wherein the aluminum material is charged with a current having an alternating wave form rich in cathodic component in the electrolytic coloring cell. 10. A process for electrolytically treating aluminum or its alloy in the form of a strip, wire or foil material in a continuous manner which comprises continuously passing the material first through a negatively charging cell, then through an anodic oxidation treatment cell and finally through an electrolytic coloring cell, each cell containing therein an electrolytic solution and comprising an electrode immersed in the electrolytic solution; wherein a circuit is formed by commonly connecting to the electrode in the negatively charging cell a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the electrode in the anodic oxidation treatment cell and said power source for electrolytically coloring being further connected to the electrode of the electrolytic coloring cell, said power source for anodizing being DC and the power source for electrolytically coloring being AC, or the power source for both of them being a single AC-superimposed DC, whereby a current having an alternative wave form rich in positive component is supplied to the electrode of the electrolytic coloring cell, and the aluminum material is negatively charged through the electrolytic solution in the negatively charging cell, anodized in the anodic oxidation treatment cell and colored in the electrolytic coloring cell. 11. The process according to claim 10, wherein the electrolytic solution in the electrolytic coloring cell contains a tin salt. 12. The process according to claim 10, wherein the electrolytic solution in the electrolytic coloring cell contains a tin salt and at least one member selected from the group consisting of nickel salts, cobalt salts, iron salts, magnesium salts, and zinc salts. 13. The process according to claim 10, wherein the electrolytic solution in the electrolytic coloring cell contains at least one member selected from the group consisting of copper salts, selenium salts, manganese salts and zirconium salts. 14. The process according to claim 10, wherein the aluminum material is charged with a current having an alternative wave form rich in cathodic component in the electrolytic coloring cell. 15. A process for electrolytically treating aluminum or its alloy in the form of a strip, wire or foil material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell comprising a negatively charging compartment and an anodizing compartment separated from each other by a diaphragm with a slit for passing the aluminum material and then through an electrolytic coloring cell, each of said negatively charging compartment, anodizing compartment and electrolytic coloring cell containing an electrolytic solution and comprising an electrode immersed in the electrolytic solution; wherein a circuit is formed by commonly connecting to the electrode in the negatively charging compartment a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the electrode in the anodizing compartment, said power source for electrolytically coloring being further connected to the electrode in the electrolytic coloring cell, said power source for anodizing being DC and the power source for electrolytically coloring being AC, or the power source for both of them being a single AC-superimposed DC, whereby a current having an alternative wave form rich in positive component is supplied to the electrode of the electrolytic coloring cell, and the aluminim material is negatively charged through the electrolytic solution in the negatively charging compartment, anodized in the anodizing compartment and colored in the electrolytic coloring cell. 16. The process according to claim 15, wherein the electrolytic solution in the electrolytic coloring cell contains a tin salt. 17. The process according to claim 15, wherein the electrolytic solution in the electrolytic coloring cell contains a tin salt and at least one member selected from the group consisting of nickel salts, cobalt salts, iron salts, magnesium salts, and zinc salts. 18. The process according to claim 15, wherein the electrolytic solution in the electrolytic coloring cell contains at least one member selected from the group consisting of copper salts, selenium salts, manganese salts and zirconium salts. 19. The process according to claim 15, wherein the aluminum material is charged with a current having an alternative wave form rich in cathodic component in the electrolytic coloring cell.