JPS5919998B2 - Electrolytic treatment method of aluminum or aluminum alloy using air bubbles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to aluminum or an aluminum alloy (hereinafter referred to as "
"Aluminum".

) in the presence of air bubbles, the purpose of which is to electrolytically treat aluminum by bringing the surface of aluminum into local contact with an electrolytic solution using air bubbles, thereby creating a state suitable for patterned color finishing. The purpose is to provide aluminum surfaces. Conventionally, when the surface of aluminum is colored by electrolytic treatment, it is almost a single color, and for pattern finishing, the anodized film is partially covered with a resist film, dyed, and then the resist film is peeled off, and the bore of the anodized film is used. There are methods such as enclosing a photosensitizer inside and taking photographs, printing screen, gravure, octopus, etc. on the anodic oxide film, and finishing the pattern with painting, but all of them require complicated and expensive processes. It didn't happen.

Moreover, the patterns formed on the surface by such methods usually have poor weather resistance due to the coloring caused by organic substances, and are often unable to withstand outdoor use such as building materials. Additionally, the "Pattern Finishing Method for Aluminum or Aluminum Alloy" (Japanese Unexamined Patent Publication No. 52-70951) and the "Surface Treatment Method for Aluminum or Aluminum Alloy" (Japanese Unexamined Patent Publication No. 52-70952) recently disclosed by the applicant of the present application are It has the advantage of being able to create any clear and weather-resistant pattern on the aluminum surface, but the process of drawing the pattern during the barrier layer growth process or the process of masking the oxide film is complicated, which reduces work efficiency. Another drawback is that it is not possible to apply patterns to intricate parts of objects with special shapes, such as extruded materials. Therefore, the present inventors have conducted extensive research in order to eliminate the drawbacks of the above-mentioned conventional methods, and as a result, by creating bubbles in the electrolytic solution and utilizing these bubbles when electrolytically treating aluminum,
We have discovered that it is possible to locally electrolyze the surface of aluminum. The present invention was completed based on this knowledge. That is, the present invention is characterized in that aluminum subjected to anodizing treatment is electrolytically treated in an electrolytic solution containing an acid and/or salt, a foaming agent and/or a foaming stabilizer, and in which bubbles are present. The present invention provides a method for electrolytically treating aluminum. A major feature of the method of the present invention is that, as described above, bubbles are caused to exist in the electrolytic solution. Aluminum that has been anodized is immersed in an electrolytic solution, and air bubbles are created at the interface between the aluminum and the electrolytic solution. Thus aluminum Table 5
There are parts of the surface that come into contact with the electrolyte and parts that do not. Therefore, if electricity is applied in this state, only the portion of the aluminum surface that is in contact with the electrolyte will be electrolyzed.

In the method of the present invention, it is not preferable that the bubbles attached to the surface of the aluminum move or disappear during energization, and it is desirable that the bubbles adhere stably.

If bubbles move or disappear during energization, the part of the aluminum surface that receives electrolysis changes, and the bubbles move or disappear.
If the loss is severe, the entire aluminum surface will be subjected to electrolysis on average, making it impossible to achieve the object of the present invention. Therefore, it is desirable that the current application time be short. Furthermore, it is effective to add a foaming agent and/or a foaming stabilizer to the electrolytic solution for the purpose of stably generating bubbles in the electrolytic solution. As the foaming agent, a surface active agent is usually used, and as the foaming stabilizer, a chemical having a thickening effect such as glycerin is suitable. Although there are no particular restrictions on the means for generating bubbles in the electrolytic solution, it is generally carried out by blowing air through a pipe or the like from the bottom of the electrolytic cell, particularly from below the aluminum to be treated.
In this case, it is preferable that air is blown in to generate air bubbles before energization, and that the air blowing is stopped when energization is applied. By doing so, the electrolyte comes into contact with only a certain portion of the aluminum surface, making it possible to conduct local current. The method of the present invention is applicable to the above-mentioned "Pattern finishing method for aluminum or aluminum alloy" (Japanese Patent Application Laid-Open No. 70951/1982) and "Surface treatment method for aluminum or aluminum alloy" (Japanese Patent Application Laid-Open No. 52-70951). -70
952), etc.

In the above-mentioned "Pattern Finishing Method for Aluminum or Aluminum Alloy" (Japanese Unexamined Patent Publication No. 52-70951), in the barrier layer growth step, a boric acid monoborax mixed solution, ammonium tartrate, boric acid, ammonium carbonate, citric acid, If the method of the present invention is applied using an electrolytic solution such as tartaric acid or ammonium borate, the aluminum surface will be locally energized by the action of bubbles, and the barrier layer will grow only in that area, preventing subsequent color development. During the process, there will be a difference in the degree of color development compared to other parts. On the other hand, in "Surface treatment method for aluminum or aluminum alloy" (Japanese Unexamined Patent Publication No. 70952/1983), barium nitrate, calcium nitrate, magnesium nitrate, zinc sulfate,
When the method of the present invention is applied using an electrolytic solution such as oxalic acid or malonic acid, local energization progresses due to the action of bubbles, and pores in the oxide film at the energized portions are masked. As a result, in the subsequent coloring step with metal salt, metal precipitation is prevented in this portion, and a honeycomb-like pattern is formed as a whole.
In the method of the present invention, any current such as alternating current, direct current, or other pulsed current may be used for electrolysis. Further, although there is no particular restriction on the voltage to be applied, it is preferable to increase the inter-electrode voltage in consideration of the fact that liquid resistance is generally high. As described above, the method of the present invention is an extremely simple process and can be applied to aluminum of any shape and to various coloring methods, making it highly versatile and economically advantageous. It is.

Furthermore, aluminum products colored with patterns using the method of the present invention not only have superior aesthetics compared to conventional products, but also have significantly improved performance such as corrosion resistance, chemical resistance, and weather resistance. Become. Therefore, the products obtained by the method of the present invention can be suitably used as building materials. Next, the method of the present invention will be explained in more detail with reference to Examples.

First, a pretreatment process for aluminum will be shown as a reference example. Reference Example A-6063-T5 aluminum was degreased and washed, and 6
% caustic soda aqueous solution for 5 minutes at 60°C.

Then, the smut was removed in a 10% nitric acid aqueous solution. Thereafter, in an electrolytic solution of 15% sulfuric acid aqueous solution (dissolved Al59/l), the above aluminum was used as an anode and a separately prepared aluminum was used as a cathode, and the electrolysis temperature was 20°C and the current density was 1A/D.
Anodizing treatment was performed by applying direct current under the conditions of TrI and an electrolysis time of 35 minutes. Example 1 An aqueous solution consisting of 30 g of boric acid/11 borax 199/11 foaming agent (trade name: Ripon F, manufactured by Lion Yushi Co., Ltd.) 5 ml of 1/11 glycerin 100 d/l was put into a beaker as an electrolyte, and then A glass tube was inserted into the liquid and air was blown into it to create bubbles.

Thereafter, the anodized aluminum plate produced in the reference example was placed in the bubble, and DC current was applied at a voltage of 100 for 30 seconds using the aluminum as an anode and SUS3O4 stainless steel as a cathode. Next, in a 4% aqueous sulfuric acid solution, alternating current was applied for 3 minutes and 30 seconds at a temperature of 28° C. and a voltage of 3V1, using the aluminum as one electrode and a prepared Al plate as a counter electrode. As a result, a white honeycomb-like pattern was obtained on the aluminum surface with a reddish-gold color. Example 2 The aluminum to be treated in Example 1 was made into an extruded material having a complicated shape, a ceramic filter was attached to the tip of the glass tube, and the electrolytic coloring process was performed using nickel sulfate 259/l instead of 4% sulfuric acid. , boric acid 209/
11 Using an aqueous solution of pH 5 consisting of 259/l of magnesium sulfate as the electrolyte, the temperature was 20°C and the voltage was 12V.
The operation was carried out under the same conditions as in Example 1, except that the test was carried out for a minute.

As a result, the surface of the extruded material and the inside of the intricate shape were colored in a light upper color and a fine hexagonal pattern was applied. Example 3 Barium nitrate 209/l, glycerin 109/l, foaming agent (trade name: Lypon F, manufactured by Lion Oil Co., Ltd.) 10
An aqueous solution of ml/l was put into a beaker as an electrolyte, and then a glass tube was inserted into the solution and air was blown into the solution to create bubbles.

Thereafter, the anodized aluminum produced in the reference example was placed in the bubble, and the aluminum was placed on one electrode,
Voltage 100 using SUS3O4 stainless steel as the counter electrode
AC current was applied for 30 seconds. Then stannous sulfate 79/
PH consisting of 11 tartaric acid 309/11 boric acid 109/l
Using an aqueous solution of No. 7.5 as an electrolytic solution, alternating current was applied for 2 minutes at a temperature of 25° C. and a voltage of 10 V using the above aluminum as one electrode and a prepared SUS3O4 stainless steel plate as a counter electrode. As a result, a cold-colored white honeycomb pattern was obtained on the aluminum surface.

[Brief explanation of the drawing]

FIG. 1 shows an aluminum plate electrolytically treated using the method of the invention.

Claims (1)

[Claims] 1. Aluminum or aluminum alloy which is characterized by electrolytically treating anodized aluminum or aluminum alloy in an electrolytic solution containing an acid and/or salt and a foaming agent and/or foaming stabilizer and in which bubbles are present. Electrolytic treatment method for aluminum alloy.