JPS59140397A - Coloring method of aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To obtain stably a colored film having a bright color tone in a primary color system in a method for electrolytic coloring of an Al material after anodization by repeating alternately two kinds of superposed AC and DC electrolytic treatments at different electrolytic voltages in anodization. CONSTITUTION:Al or an Al alloy is anodized by alternate repetition of two kinds of superposed AC and DC electrolytic treatments at different electrolytic voltages at an optional ratio. The film structure can then be reformed quickly and uniformly without damaging the film. The film structure is more satisfactorily reformed as the number of repetition of two kinds of the superposed AC and DC electrolytic treatments is larger and therefore about >=10 times are required in order to obtain a colored film having the color tone of the primary color system. Since the color tone of the colored film is determined by the reforming condition of the film structure, said condition varies with the difference in electrolytic voltage, bath compsn. and bath temp., etc. in addition to the above- mentioned number of repetition. The Al after the anodization is electrolytically colored in an aq. soln. contg. metallic salt, thereby the colored film having the color tone of blue, green, orange, purple, etc. is stably obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coloring aluminum or an aluminum alloy (hereinafter both will be collectively referred to simply as aluminum).

Conventionally, when coloring aluminum, the generally well-known coloring method is to oxidize the aluminum with eight electrodes and then electrolyze it in an aqueous solution containing a metal salt or with a direct current cathode.Although other organic and inorganic coloring methods and physical Unlike conventional electrolytic coloring methods, the colored film has excellent weather resistance and wear resistance, so it is widely applied to color various aluminum materials, including aluminum sash, which is essential for modern architecture. The color tones obtained with this method are limited to those of amber or bronze threads, and although the shading of the coloring can be adjusted to some extent depending on the processing conditions, it is not possible to obtain the vivid tones of primary colored threads such as purple, orange, green, and blue. Ta.

The method of the present invention was developed in order to solve the above-mentioned problems.In addition to coloring aluminum, the method of the present invention involves alternatingly repeating two types of AC/DC superimposed electrolytic treatments with different electrolytic voltages at an arbitrary time ratio. Oxidation treatment is performed to form an anodic oxide film with a microstructure different from a normal anodic oxide film on the surface of aluminum, and then an electrolytic coloring treatment is performed in an aqueous solution containing metal salts to create a luminescent coating. This is a method of obtaining a colored film with vivid primary color tones through interference effects.

To explain the method of the present invention in more detail below, in the case of the present invention, the colored film is obtained by a simple process of anodizing aluminum and then electrolytically coloring it. The most significant feature is that anodic oxidation is performed while alternating AC/DC superimposed electrolytic treatment at an arbitrary time ratio.

Of the two types of AC/DC superimposition techniques 9 and treatments in the anodizing process, the one with a higher DC voltage is mainly intended to form an anodic oxide film, and the one with a lower DC voltage is a film structure with current recovery. The main purpose is to improve the former by electrolytic treatment,
In other words, when the purpose is to form an anodic oxide film, the electrolytic voltage can be set depending on the bath composition and temperature of the electrolytic bath, and the latter electrolytic treatment, that is, one that involves current recovery, is a direct current The larger the difference in voltage, the stronger the effect of modifying the film structure and the easier it is to obtain a vivid color tone when electrolytically colored in the first step.

In this case, if the difference in DC voltage between the two types of AC/DC superimposed electrolytic treatments is 5V or less, only a bronze-like dark color tone can be obtained. A voltage difference of more than 100% is required.

Regarding the effects of AC/DC superimposed electrolysis in the method of the present invention, please refer to @
When AC/DC superposition electrolysis is performed for the purpose of forming a polar oxide film, compared to the case where other waveforms are used, current recovery by the next AC/DC superposition electrolysis is carried out more easily and uniformly, and on the other hand, When AC/DC superimposed electrolysis is used for the purpose of current recovery, the recovery time is shorter than when direct current is used, and film breakdown tends to be less likely to occur than when alternating current is used. be.

In view of the above, in the method of the present invention, the film structure can be modified quickly and uniformly without damaging the film by repeating two types of AC/DC superimposed electrolysis treatments with different electrolysis voltages alternately at an arbitrary time ratio. It is possible.

At this time, regarding the number of repetitions of two types of AC/DC superimposed electrolysis with different electrolysis voltages, the film structure is improved as the number of repetitions increases. It is necessary to repeat the process more than once; if the process is repeated less than this time, only a bronze tone or a dark primary color can be obtained as seen in conventional electrolytic coloring.

In addition, regarding the time ratio of the two types of AC/DC superimposed electrolysis,
In the case of AC/DC superposition electrolysis for the purpose of forming an anodic oxide film, the energization time required to obtain the required film thickness is determined by the electrolytic voltage and number of cycles. On the other hand, in AC/DC superimposition electrolysis for the purpose of current recovery, the time when current recovery is completed may be set as the energization time.

As mentioned above, the color tone of the colored film obtained by the method of the present invention is determined by the modification state of the film structure in the anodizing process, so the number of repetitions of the two types of AC/DC superimposed electrolytic treatments, the electrolytic voltage difference, By determining the bath composition, bath temperature, and other conditions, it is possible to stably obtain a colored film with the vivid color tones of primary color threads such as blue, green, orange, and purple through subsequent electrolytic coloring.

Regarding the bath used in the coloring method of the present invention, in the case of anodizing treatment baths, commonly used baths containing sulfuric acid, sulfamic acid, oxalic acid, etc. are sufficient, and in the case of electrolytic coloring treatment, nickel Electrolytic coloring may be carried out using a waveform of direct current, alternating current, etc. in a bath containing metal salts such as copper, cobalt, etc.

As mentioned above, if the method of the present invention is applied to coloring aluminum, an anode having a fine structure on the surface of aluminum can be produced by repeating two types of AC/DC superimposed electrolytic treatments with different electrolytic voltages alternately at an arbitrary time ratio. Forms an oxide film, then
Through a simple process of electrolytic coloring in an aqueous solution containing metal salts, it is possible to obtain a brightly colored film of primary colored threads due to the interference effect of light, so the colored film has good weather resistance and abrasion resistance. Together with this, it is greatly useful for coloring various aluminum materials including aluminum satsushi.

Hereinafter, specific examples of the present invention will be shown below.

Example 1 Two plates of aluminum alloy (6063S-T5) were used as samples, and at the same time, a 15V DC anode was applied with carbon as the counter electrode in 150 l/l of sulfuric acid and a bath temperature of 30'C.
AC/DC superposition electrolysis was performed for 25 minutes by applying an AC voltage of 7 V between the samples.
At the same time, apply a DC anode of 5μ for 2 seconds, and at the same time
AC/DC superimposed electrolysis applying an AC voltage of V was repeated 15 times, 30 times, 40 times, and 50 times at a time ratio of 5 seconds.
1tm, 12. Two samples each having an anodic oxide film of Oltm were obtained.

Next, one of each sample was colored in 8 colors using carbon as an anode in a bath of 5 sulfuric acid, 5 to 5 sulfuric acid, and carbon as an anode at a DC voltage of 10 V and a coloring time of 60 seconds, resulting in a colored film as shown below. Obtained.

Example 2 Two plates of aluminum alloy (60638-T5) were used as samples, and a 15V DC @ electrode was applied with carbon as the counter electrode in a 150-year sulfuric acid bath at a temperature of 33°C.At the same time, a 7V AC voltage was applied between the samples. AC/DC superimposed electrolysis is applied for 25 seconds,
AC/DC superimposed electrolysis in which a DC anode of 5 V is applied and at the same time an AC voltage of 6 mm is applied between the samples is repeated 25 times at a time ratio of 50 seconds to form an anodic oxide film of 11.0 .mu.m each.

Next, when one of the samples was electrolytically colored in the same manner as in Example 1, a green colored film was obtained.Example 3 Two plates of aluminum alloy (6063S-T5) were used as samples, At a bath temperature of 30°C, a 14V DC anode was applied using carbon as the counter electrode, and at the same time, an AC/DC superposition electrolysis was performed by applying an AC voltage of 8μ between the samples for 25 seconds, and a DC anode of 5μ was applied at the same time. , AC/DC superimposed electrolysis in which an AC voltage of 7 μm is applied between the samples is repeated 40 times at a time ratio of 50 seconds to form an anodic oxide film of 11.0 μm each.

Next, one of the samples was added to 5I of stannous sulfate! /l, @ acid54
When electrolytic coloring was carried out in a room temperature bath at an AC voltage of 12 V for 60 seconds using carbon as a counter electrode, an orange colored film was obtained.

Example 4 Two plates of aluminum alloy (60638-T5) were used as samples and anodized in the same manner as in Example 3, and then nickel was used as the counter electrode in a bath of 50% nickel sulfate, 30% boric acid, and room temperature. One of the samples was applied with an AC voltage of 15V, and the other one was
When each sheet was electrolytically colored for 60 seconds using a 15 V DC cathode, an orange colored film was obtained in both cases.

Example 5 Two aluminum alloy (60638-T5) plates were used as samples.
At 3°C, a DC anode of 30V was applied using carbon as the counter electrode, and at the same time an AC voltage of 9V was applied between the samples. AC/DC superimposed electrolysis was performed for 25 seconds. By repeating AC/DC superimposed electrolysis applying an AC voltage of 40 times and 50 times at a time ratio of 50 seconds, anodic oxide films of 9.0 μm and 11.0 μm were formed on two samples each. I got it.

Next, one sheet of each sample was electrolytically colored in a bath of stannous sulfate for 5 to 5 years and sulfuric acid for 5 years at room temperature, using carbon as an anode, a DC voltage of 20 V, and a coloring time of 60 seconds.

A colored film as shown below was obtained.

Example 6 Two aluminum (IlooP) plates were used as samples, and oxalic acid was applied at 50 to 30 V with carbon as the counter electrode in a bath temperature of 43°C.
AC/DC superimposed electrolysis was performed for 25 seconds by applying a DC anode of 20 V and an AC voltage of 7 V between the samples. The process is repeated 50 times at a time rate of seconds to form an anodic oxide film each having a thickness of 12.0 μm.

Next, one of the samples was electrolytically colored in the same manner as in Example 5, and a blue colored film was obtained.

Claims (2)

[Claims] (1) Aluminum or aluminum alloy is anodized by repeating two types of AC/DC superimposed electrolytic treatments with different electrolytic voltages alternately at an arbitrary time ratio, and then coloring of the electrolytic layer is performed in an aqueous solution containing a metal salt. A method for coloring aluminum or aluminum alloy. (2) The method for coloring aluminum or aluminum alloy according to claim 1, wherein the difference in DC voltage between the two types of AC/DC superimposed electrolytic treatments is 5 V or more.