GB2567505A

GB2567505A - Aluminium panels

Info

Publication number: GB2567505A
Application number: GB1802186.5A
Authority: GB
Inventors: Edge Colin
Original assignee: Multitechnic Ltd
Current assignee: Multitechnic Ltd
Priority date: 2017-02-10
Filing date: 2018-02-09
Publication date: 2019-04-17
Also published as: US20180230617A1; FR3062812A1; GB201702213D0; GB201802186D0

Abstract

An aluminium or aluminum alloy panel 1 comprises an upper surface and a lower surface. The upper surface comprises at least one recessed area 4. The panel 1 has a reduced thickness in the at least one recessed area 4. Both the upper surface of the panel and the at least one recessed area 4 are provided with an aluminium oxide (anodized) coating (figure 4, 6). The anodised coating includes the addition of a dye. A method for producing an aluminium panel 1 is also detailed where a panel 1 is anodised and then a part of the anodised coating 2 and the underlying panel (figure 3, 5) is removed thus creating a recessed area 4. This is then subjected to an anodising process 6’ and is further sealed. A stencil (figure 4, 3) may be used to locate the recessed area. Sulfuric (sulphuric) acid can be used in the anodising process to produce coating of 1.8-25µm thickness. A dye may also be added to the anodised coating. The anodised coating may also be sealed using hot water sealing or cold sealing through the use of a nickel salt. The method can be used in manufacture of aluminium signs or nameplates.

Description

Aluminium Panels

Field of the Invention

The present invention relates to panels made from anodised aluminium and from anodised aluminium alloys and a method for producing such panels, and in particular to panels including a recessed design.

Background of the Invention

Aluminium signs or nameplates are typically made from anodised aluminium panels.

Anodising is an electrochemical process which provides the surface of a metal, such as aluminium, with an oxide coating. This anodised coating is porous and can absorb dyes to provide the panel with a coloured layer. The anodised coating must then be sealed using a sealing process which seals the pores in the coating. Anodising increases corrosion and wear resistance of the panel and the anodised coating is non-conductive of electricity.

Sulphuric acid is commonly used in the preparation of anodised aluminium, producing coatings of moderate thickness, for example 1.8 gm to 25 gm thick. These coatings are known as type II coatings.

Different sealing processes are commonly used, including hot water sealing where the panel is immersed in boiling de-ionised water for a certain amount of time, and cold sealing methods, where for example the panel may be immersed in a solution of a nickel salt, such as nickel fluoride.

Pre-anodised aluminium sheets are often used in making signs. Designs can be engraved or etched into the anodised panels and paint can be added to the etched or engraved areas. However, since the paint is applied to the metal surface it is less durable than dyes encapsulated within the anodic layer and also vulnerable to both wear and damage and degradation from solvents, pollutants or the environment.

Anoprinting is an alternative known method of printing onto aluminium panels to make signage. This process involves printing onto a freshly anodised, unsealed, porous surface, allowing the dyes to soak into the surface. After the colour has been applied the anodised coating is sealed to trap the dye inside the anodised surface layer. In this process there is no etching and/or engraving so the surface of the signs is smooth and when a smooth surface is contaminated with dirt or soot it can be difficult to read. With signage of this type there is also no option to make the surface of the signs tactile and it can be difficult to read such signage from certain angles or in certain light conditions since the reflection from the surface is uniformly smooth. In addition, if the printed image becomes bleached for example through exposure to heat or light the image will be reduced in intensity or lost entirely This type of signage is also unsuitable for use on a floor as the smooth surface is likely to provide a slip hazard, particularly when wet.

It would therefore be desirable to provide an improved aluminium panel.

Summary of the Invention

According to the invention there is provided an aluminium panel or an aluminium alloy panel comprising an upper surface and a lower surface, the upper surface comprising at least one recessed area, the panel having a reduced thickness in the at least one recessed area, wherein both the upper surface of the panel and the at least one recessed area are provided with an aluminium oxide coating, and wherein the aluminium oxide coating of the at least one recessed area includes at least one coloured dye.

The depth of the recessed area should be sufficient to be discernible by sight or touch, preferably at least 0.1mm relative to the upper surface of the panel.

Preferably the aluminium oxide coating is obtained by electrolytic anodising treatment. More preferably the electrolytic anodising treatment is a sulphuric acid electrolytic anodising treatment.

The aluminium oxide coating of the at least one recessed area may be unsealed. Alternatively, the aluminium oxide coating of the at least one recessed area may be sealed. Anodised aluminium oxide coatings are preferably sealed using a standard sealing process selected from the group comprising: hot water sealing, steam sealing, nickel salt cold sealing, chromate sealing and dichromate sealing processes.

The aluminium oxide coating of the recessed area may include more than one dye. The aluminium oxide coating of the upper surface of the panel may include at least one dye. The aluminium oxide coating of both the upper surface of the panel and the aluminium oxide coating of the recessed area may each include at least one dye. The dye included in the aluminium oxide coating of the upper surface of the panel may be a different colour to the dye included in the aluminium oxide coating of the recessed area.

The aluminium panel may be selected form the group comprising: labels, nameplates, signs, badges, and flooring.

According to a further aspect of the invention there is provided a method for producing an aluminium panel comprising the steps of:

(a) taking an aluminium panel, the panel comprising an upper surface and a lower surface, the upper surface having an anodised coating, and removing part of the aluminium oxide coating and a proportion of the underlying aluminium to create a recessed area on the panel; and (b) connecting the panel to a power supply and anodising the exposed aluminium parts of the recessed area of the panel such that the recessed area is provided with an aluminium oxide coating.

The method may comprise a final step of:

(c) sealing the anodised coating of the recessed area.

Preferably the aluminium oxide coating on the panel in step (a) is obtained by electrolytic anodising treatment. More preferably, the electrolytic anodising treatment is a sulphuric acid electrolytic anodising treatment.

The method may include an additional step of applying at least one coloured dye to the panel after step (b) and before step (c).

Preferably, the recessed area created in step (a) has a depth of at least 0.1mm relative to the upper surface of the panel.

Step (a) may be a two-step process, and comprises the steps of first removing the anodised coating, and the subsequently removing the underlying aluminium. Each step of the two-step process may use a different removal process.

In step (a) the anodised coating may be removed by a process selected from the group comprising: chemical etching, engraving, laser engraving and sand blasting.

In step (a) the underlying aluminium may be removed by a process selected from the group comprising: chemical etching, engraving, laser engraving and sand blasting.

Preferably, in step (c) the anodised coating is sealed using a standard sealing process selected from the group comprising: hot water sealing, steam sealing, nickel salt cold sealing, chromate sealing and dichromate sealing processes. Where the sealing process is a hot water sealing process and the anodised coating is sealed by immersion in hot water, preferably water at a temperature of between 96 and 100 °C, for a period of at least 20 minutes.

The aluminium panel used in the method may be selected form the group comprising: labels, nameplates, signs, badges, and flooring.

The term aluminium panel includes panels made from aluminium or alloys of aluminium.

Brief Description of the Drawings

In the Drawings, which illustrate preferred embodiments of the invention:

Figure la is a perspective view of an aluminium panel with an etching stencil applied;

Figure lb is a cross section of the panel of Figure la, through the line X-X;

Figure 2 is the cross section of Figure lb after a first etching process;

Figure 3 is the cross section of Figure lb after a second etching process;

Figure 4 illustrates the cross section of Figure lb after re-anodising the etched areas of the panel;

Figure 5 illustrates the panel after immersion in a dye solution;

Figure 6a illustrates a cross section through the panel after the etching stencil has been removed; and

Figure 6b illustrates a perspective view of the panel of Figure la after treatment with the method of the invention.

Detailed Description of the Prior Art and Preferred Embodiments of the Invention

Figure la illustrates a panel of anodised aluminium 1. A cut-vinyl etching stencil 3 has been applied to the anodised surface coating, leaving an area 4 of the surface exposed.

Figure lb illustrates the cross-section taken along the line X-X. It can be seen in Figure lb that the aluminium panel 1 has an anodised coating 2 at its upper surface. The anodised coating 2 is a layer of aluminium oxide formed during an electrolytic process which has been subsequently sealed using a standard sealing process. The anodised coating 2 may have been immersed in a dye solution prior to sealing, so may be coloured.

The anodised coating 2 is removed from the exposed area 4 by applying an etching solution. Figure 2 shows the anodised coating removed in the area 4 exposed by the stencil 3, exposing the underlying aluminium metal 5.

The panel 1 is then further etched or engraved to increase the depth of the image area 4 to form a recessed area on the panel 1, as shown in Figure 3. Any suitable etching or engraving method which removes material to produce a recessed area may be used.

The panel 1 is then connected to a power supply and the exposed aluminium surface 5 is re-anodised using a standard anodising method, to produce an anodised coating 6, as shown in Figure 4, typically of around 25 pm thickness. Since the original anodised coating 2 does not conduct electricity it is unaffected by this second anodising step.

At this stage, the freshly anodised coating 6 is porous and may be dyed by immersing in a dye solution, resulting in a coloured anodised coating 6’ as shown in Figure 5. Since only the freshly anodised coating 6 is porous it is only this part which absorbs the dye, meaning that the recessed parts of the panel may be dyed a different colour to the original panel. The panel 1 is then sealed using standard sealing methods known in the art, such as hot water sealing or cold sealing methods using Nickel salts for example.

Lastly, as shown in Figures 6a and 6b, the stencil 3 is removed to reveal a recessed area 4 which has been coloured a different colour to original anodised coating 2.

The application of dye is an optional step and the anodised coating may be sealed without dyeing to produce a transparent layer.

The following example exemplifies the method of the invention:

Example 1 (i) A piece of anodised aluminium plate with an anodised coating of thickness 25pm had a simple cut-vinyl etching stencil applied to the anodised surface.

(ii) The anodised coating from the area exposed by the stencil was then removed by etching in 5% NaOH solution at 20°C for about 3 minutes until the aluminium metal surface became visible.

(iii) The panel was then rinsed in water.

(iv) Using a standard spray etching machine, the panel was then etched in 20% Ferric Chloride solution at 20°C for 15 minutes to increase the depth of the area exposed by the stencil.

(v) The panel was then rinsed in water.

(vi) The panel was then connected to a power supply and was anodised in a tank using lead cathodes in a solution of 10% H2SO4 at 20°C using a current of .018A at 15v for 50 minutes to produce an anodised coating of thickness of approximately 25qm.

(vii) The panel was then removed from the power supply and was rinsed in de-ionised water.

(viii) The panel was then immersed in a standard black anodising dye solution for 20 minutes at 20°C until the dye had fully coloured the applied anodised parts from step (vi).

(ix) The panel was then rinsed in water.

(x) The panel was then immersed for 30 minutes in a standard sealing tank containing water at 97.5°C.

(xi) The stencil was then peeled from the surface and adhesive residue removed using a proprietary general purpose washing solvent.

Masking, or similar techniques may be employed to enable more than one coloured dye to the panel.

Panels produced using this method include recessed detail or graphics and are useful as labels, name plates, signs, badges, or flooring for example. The recessed detail may help to enable improved tactile discernment of the information or graphics. The recessed design can also produce different reflective properties between the upper surface of the panel and the recessed surface.

Claims

1. An aluminium panel comprising an upper surface and a lower surface, the upper surface comprising at least one recessed area, the panel having a reduced thickness in the at least one recessed area, wherein both the upper surface of the panel and the at least one recessed area are provided with an aluminium oxide coating and wherein the aluminium oxide coating of the at least one recessed area includes at least one coloured dye.

2. An aluminium panel according to Claim 1, wherein the aluminium oxide coating of the at least one recessed area is unsealed.

3. An aluminium panel according to Claim 1, wherein the aluminium oxide coating of the at least one recessed area is sealed.

4. An aluminium panel according to any preceding claim, wherein the depth of the recessed area is sufficient to be discernible by sight and/or touch.

5. An aluminium panel according to Claim 4, wherein the depth of the recessed area is at least 0.1mm relative to the upper surface of the panel.

6. An aluminium panel according to any preceding claim, wherein the aluminium oxide coating is obtained by electrolytic anodising treatment.

7. An aluminium panel according to Claim 6, wherein the electrolytic anodising treatment is a sulphuric acid electrolytic anodising treatment.

8. An aluminium panel according to any preceding claim, wherein the aluminium oxide coating of the upper surface of the panel includes at least one dye.

9. An aluminium panel according to Claim 8, wherein the at least one dye included in the aluminium oxide coating of the upper surface of the panel is a different colour to the at least one dye included in the aluminium oxide coating of the recessed area.

10. An aluminium panel according to any preceding claim wherein the panel is selected from the group comprising: labels, nameplates, signs, badges, and flooring.

11. A method for producing an aluminium panel comprising the steps of:

12. A method according to Claim 11, further comprising a final step of:

(c) sealing the anodised coating of the recessed area.

13. A method according to Claim 12, wherein in step (c) the anodised coating is sealed using a standard sealing process selected from the group comprising: hot water sealing, steam sealing, nickel salt cold sealing, chromate sealing and dichromate sealing processes.

14. A method according to Claim 12 or 13, wherein the sealing process is a hot water sealing process and the anodised coating is sealed by immersion in hot water, preferably water at a temperature of between 96 and 100 °C, for a period of at least 20 minutes.

15. A method according to any of Claims 11 to 14, wherein in step (a) the aluminium oxide coating on the panel is obtained by electrolytic anodising treatment.

16. A method according to any of Claims 11 to 14, wherein the electrolytic anodising treatment is a sulphuric acid electrolytic anodising treatment.

17. A method according to any of Claims 11 to 16, comprising an additional step of applying at least one coloured dye to the panel after step (b).

18. A method according to any of Claims 11 to 17, wherein in step (a) the recessed area of the panel has a depth of at least 0.1mm relative to the upper surface of the panel.

19. A method according to any of Claims 11 to 18, wherein step (a) is a two-step process and comprises the steps of first removing the anodised coating, and subsequent removal of the underlying aluminium.

20. A method according to any of Claims 11 to 19, wherein in step (a) the anodised coating is removed by a process selected from the group comprising: chemical etching, engraving, laser engraving and sand blasting.

21. A method according to any of Claims 11 to 19, wherein in step (a) the underlying aluminium is removed by a process selected from the group comprising: chemical etching, engraving, laser engraving and sand blasting.

22. A method according to any of Claims 11 to 21, wherein the aluminium panel is selected from the group comprising: labels, nameplates, signs, badges, and flooring.