JPS6130038B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a colored oxide film in a striped pattern on the surface of aluminum or its alloy (hereinafter referred to as aluminum).

Several methods have been known for uniformly coloring aluminum oxide films. For example, (a) an alloy coloring method in which the anodic oxide film is colored depending on the aluminum alloy composition, and (b) an electrolytic coloring method in which the anodized film is anodized using an organic acid as an electrolyte. (c) A secondary electrolytic coloring method in which the anodic oxide film is electrolyzed with alternating current in an aqueous metal salt solution, and (d) A dyeing method in which the anodic oxide film is immersed in an organic or inorganic dye to be colored. Although both methods were able to uniformly color the aluminum surface, they were not able to intentionally create striped patterns.

The present invention provides a method for imparting striped coloring to the above-mentioned (b) or (c) anodic oxidation film having good weather resistance, thereby creating commercial value unprecedented in the art.

The present invention uses aluminum or its alloy in a range of 0.01 to 1
A striped barrier layer film is formed by alternating current electrolysis at a voltage of 10 to 100 V in a weakly acidic or weakly alkaline aqueous solution containing % chloride. Next, the aluminum thus treated is subjected to electrolytic coloring in an organic acid or a solution containing an organic acid and sulfuric acid by a conventional method, or anodized in an acidic aqueous solution by a conventional method, and then treated with a metal salt. A desired striped colored film is formed by electrolytic coloring using a conventional method in an aqueous solution containing . If necessary, the barrier layer film obtained by AC electrolysis can be etched in an aqueous sodium hydroxide solution before coloring to make the striped pattern more distinct. After forming a striped colored film,
This is finished by performing conventional sealing treatment or painting treatment.

That is, the method of the present invention is roughly divided into two steps: a step of forming a striped pattern base on aluminum or its alloy, and a step of forming a striped pattern colored film. Either an electrolytic coloring method or an organic acid electrolytic coloring method may be used.

Next, the present invention will be specifically explained.

(A) AC electrolysis in a weakly acidic or weakly alkaline aqueous solution containing chlorides: This is an important process in forming the striped pattern. That is, the aluminum is first degreased and washed in accordance with a conventional method, and then 0.01 to 1% chloride is added to a weakly acidic or weakly alkaline aqueous solution that forms a barrier type oxide film without violently dissolving the entire surface with a strong acid or strong alkali. When alternating current electrolysis is performed in the added solution, uniform hydrogen gas is initially observed to be generated from all over the aluminum surface, but after a few seconds, the gas generation decreases and the current also decreases. This is because a barrier type oxide film has begun to form on the aluminum. The coating thus obtained is called a barrier layer, active layer coating, or insulating coating. After another 1-2 minutes, a large amount of bubbles locally rises. This is caused by the concentration of current at defective areas in the barrier layer film, where the dissolution reaction of the oxide film or aluminum is promoted due to the local stirring effect of rising bubbles. This reaction is accelerated more vigorously by the presence of chloride ions. In this way, the area where the barrier type film is locally dissolved linearly along the rising bubbles (Fig. 1, 3),
A striped pattern with unevenness is formed from a portion 4 where the aluminum 1 has been significantly melted and a portion 2 where the barrier layer is normally formed without being melted.

To explain this process in more detail, the AC electrolysis aqueous solution used in this process consists of (1) a weakly acidic or weakly alkaline aqueous solution for producing a barrier type film, and (2) local defects in the resulting barrier type film. and chloride to promote the dissolution reaction. By adding the chloride (2) to the aqueous solution of (1) and performing AC electrolysis, the striped pattern can be made clearer and the unevenness can be deepened. It is generally known that when aluminum is electrolyzed with alternating current in an aqueous chloride solution (for example, an aqueous sodium chloride solution), many fine pits are generated on the aluminum surface due to chlorine ions. But above
When the chloride (2) is allowed to coexist with the weakly acidic or weakly alkaline aqueous solution that produces the barrier type film (1), the barrier type film produced is destroyed by chlorine ions. Current concentrates on this destroyed part and many rising bubbles are generated. These rising bubbles form unevenness on the aluminum surface, which becomes a striped pattern.

The weakly alkaline or weakly acidic aqueous solution used in the present invention does not completely dissolve aluminum violently unlike strong acids or strong alkalis, and can form a barrier type oxide film. Examples of weakly acidic organic acids include tartaric acid, citric acid, malonic acid, maleic acid, phthalic acid, sulfosalicylic acid, cresolsulfonic acid, and succinic acid. Examples of weakly acidic inorganic acids include boric acid, carbonic acid, and phosphoric acid. Examples of weakly alkaline substances include ammonium salts of weakly acidic organic and inorganic acids, alkali hydrochloric acids, and the like. these substances
Use at concentrations of 0.1-20%. Moreover, those to which 0 to 1% of sodium hydroxide is added can also be used.

In addition, sodium chloride and potassium chloride are economical chlorides to promote foaming.
Although effective, copper chloride, iron chloride, calcium chloride, barium chloride, cobalt chloride, magnesium chloride, nickel chloride, manganese chloride, ammonium chloride, tin chloride, zinc chloride, and the like can also be used. The concentration varies depending on the type of chloride and the degree of striped pattern, but is preferably 0.01% to 1%. Below 0.01%, the effect of adding chloride cannot be expected;
If this is the case, many pits will occur and a desirable striped pattern will not be formed. A low concentration tends to produce thin and many striped patterns, while a high concentration tends to produce thick and few striped patterns.

The formation of the striped pattern requires the rising bubbles of hydrogen gas (when aluminum becomes negative) and the formation of a barrier-type oxide film (when aluminum becomes positive). For example, it is preferable to use PR waves, incompletely rectified waves, AC/DC superimposed waves).

The voltage varies depending on the electrolyte used, but is 10~
A range of 100V (preferably 15-60V) is good. If the working voltage is less than 10V, no striped pattern will be obtained, and if it is more than 100V, a lot of gas will be generated and it will not be effective. The electrolytic bath temperature is
The temperature is preferably 10°C to 40°C, preferably 15°C to 25°C, which is economical and effective.

In this way, when alternating current electrolysis is carried out at a voltage of 10 to 100 V in this process, a uneven barrier type film is formed. This is because when alternating current is used for electrolysis, bubbles are generated on the surface of the aluminum plate, making the etching uneven, which causes the formation of striped patterns.

(B) Formation of a striped colored film: This is because the striped pattern obtained in step A above is not visible to the naked eye, so a clear colored striped pattern is created and a corrosion-resistant oxide film is formed. This is the process of This coloring method may be a conventionally known metal salt secondary electrolytic coloring method (Asada method, see Japanese Patent Publication No. 38-1715) or an organic acid electrolytic coloring method. In the case of the present invention, for example, sulfuric acid,
Ni, Go, Fe,
Cu, Ag, Au, Sn, Pb, Se, Mn, Cr, Mo,
When colored by performing secondary electrolytic coloring using alternating current or direct current of 5V to 75V in an aqueous solution of metal salts such as V and Ti, the electrical resistance varies depending on the thickness of the barrier layer 2, as shown in Figure 2. , anodic oxide film 5
The amount of colored matter deposited on the porous layer varies as 6, 6', and 6''. Therefore, the color depth is different and the striped pattern is clearly visible.

Examples of the latter include sulfosalicylic acid,
When an electrolytic colored film is formed by direct current, alternating current, or AC/DC superposition using an electrolytic solution containing an organic acid such as sulfophthalic acid, phenolsulfonic acid, or oxalic acid with a small amount of sulfuric acid added as necessary, an uneven barrier is formed as shown in Figure 3. Since the colored film 5 is superimposed on the base material of the layer 2, a difference in shading occurs and the striped pattern stands out clearly.

(C) Etching of the barrier layer film: In order to make the striped pattern of the barrier layer film obtained in the above step A more clearly uneven, 5 to 10% sodium hydroxide is added before processing in the above step B. This is a step of etching by immersing it in an aqueous solution for 5 seconds to 5 minutes. As shown in Figure 4, the thickness d of the barrier layer film formed in step A is changed to the thickness b in this step.
, and becomes deeper by etching. Such etching treatment makes it easier for current to flow during the next step B described above.

If the temperature and concentration of sodium hydroxide are high and the time is long in this step, the amount of etching will increase, and the barrier layer film formed in step A will be dissolved and disappear, leaving only the irregularities on the aluminum surface. Furthermore, when the concentration is low, the temperature is low, and the etching time is short, the amount of etching is small and the barrier layer film remains. If the barrier type film remains, a more distinct striped pattern with a combination of shading and unevenness can be obtained by the subsequent treatment in step B (FIGS. 5 and 6). If no barrier layer film remains, a uniformly colored uneven striped pattern is obtained. By changing the intensity of etching in this step in this manner, it is possible to change the depth of the unevenness of the striped pattern and the difference in color shading in the final product.

In the present invention, the striped colored film thus formed is finished by sealing or painting according to a conventional method to obtain a final product. Although such products have a color satisfactorily suitable for use, they can be electrolytically colored in an aqueous solution containing a metal salt in a conventional manner to impart a richer color. That is, Ni, Co, Fe, Cu, Ag, Au,
These metals are added as metals, metal oxides, and hydroxides into a porous film previously formed by alternating current in water containing metal salts such as Su, Pb, Se, Mn, Cr, Mo, V, and Ti. It can develop a color unique to precipitated metals.

Next, the invention will be explained with reference to examples.

Example 1 A 6063 aluminum extrusion molded material that had been degreased and cleaned in a conventional manner was immersed in an aqueous solution containing 5% citric acid and 0.1% potassium chloride, and AC 40V was applied for 3 minutes using a carbon plate as a counter electrode. . At first, gas was generated violently over the entire surface, but soon gas was generated locally from certain positions. After washing this with water, 5
% sodium hydroxide aqueous solution at 50°C for 2 minutes. After that, use this as an anode.
Direct current in 15% sulfuric acid aqueous solution with carbon plate as cathode
An anodic oxide film was formed by applying 17V for 30 minutes.
Next, when this was heated in an aqueous solution containing 3% nickel sulfate, 3% boric acid, and 2.5% ammonium sulfate, and 15V AC was applied for 5 minutes using a carbon plate as the counter electrode, a dark and light bronze color with irregularities appeared. A pattern was obtained.

Example 2 A 6063 aluminum extrusion molded material that had been degreased and cleaned in a conventional manner was immersed in an aqueous solution containing 7% boric acid and 0.1% potassium chloride, and AC 25V was applied for 5 minutes using a carbon plate as a counter electrode. After washing with water, this was immersed in a 5% aqueous sodium hydroxide solution at 40° C. for 3 minutes for etching treatment. Thereafter, using this as an anode, DC 17V was applied for 30 minutes in a 15% sulfuric acid aqueous solution with the carbide plate as a cathode to form an anodic oxide film. Next, when this was heated in an aqueous solution containing 3% nickel sulfate, 3% boric acid, and 2.5% ammonium sulfate and 15V AC was applied for 5 minutes using a carbon plate as the counter electrode, uneven dark and light bronze stripes appeared. A pattern was obtained.

Example 3 A 6063 aluminum extrusion material that had been degreased and cleaned in a conventional manner was immersed in an aqueous solution containing 5% ammonium borate, 0.1% sodium hydroxide, and 0.1% sodium chloride, and a carbon plate was immersed. AC 30V was applied for 3 minutes as a counter electrode. After washing with water, this was etched by immersing it in an 8% aqueous sodium hydroxide solution at 60°C for 30 seconds. Thereafter, using this as an anode, DC 17V was applied for 30 minutes in a 15% sulfuric acid aqueous solution with the carbon plate as a cathode to form an anodic oxide film. Next, when this was heated in an aqueous solution containing 3% nickel sulfate, 3% boric acid, and 2.5% ammonium sulfate and 15V AC was applied for 5 minutes using a carbon plate as the counter electrode, uneven dark and light bronze stripes appeared. A pattern was obtained.

Example 4 AC 40V was applied for 5 minutes to a 1100 aluminum plate that had been degreased and cleaned in a conventional manner in an aqueous solution containing 3% sodium borate and 0.5% sodium chloride with a carbon plate as a counter electrode. After washing with water, it was etched in a 5% aqueous sodium oxide solution at 50°C for 1 minute, and then in a 15% aqueous sulfuric acid solution with direct current.
18V was applied for 40 minutes. Furthermore, this was exchanged in an aqueous solution containing 4% copper sulfate and 2% sulfuric acid.
When 10V was applied for 3 minutes, an uneven pattern of dark and light maroon stripes was obtained.

Example 5 AC 15V was applied for 3 minutes using a carbon plate as a counter electrode in an aqueous solution containing 1100 aluminum which had been degreased and cleaned by a conventional method and 0.1% sodium chloride. Wash this with water and apply direct current in a 15% sulfuric acid aqueous solution.
18V was applied for 40 minutes. Furthermore, this was exchanged in an aqueous solution containing 4% copper sulfate and 2% sulfuric acid.
When 10V was applied for 3 minutes, a maroon striped pattern with few irregularities was obtained.

Example 6 A 1100 aluminum plate that had been degreased and cleaned by a conventional method was heated at 60 V AC for 2 minutes with a carbon plate as the counter electrode in an aqueous solution containing 10% tartaric acid, 0.1% sodium hydroxide, and 0.1% sodium chloride. applied. After washing it with water, it was etched in a 5% aqueous sodium hydroxide solution at 50°C for 30 seconds, and then a direct current of 2 A/dm ² was applied for 30 minutes in an aqueous solution containing 10% sulfosalicylic acid and 0.5% sulfuric acid. A striped pattern of light and dark amber color with unevenness was obtained.

Example 7 A 1100 aluminum plate that had been degreased and cleaned in a conventional manner was subjected to an AC voltage of 30 V for 5 minutes using a carbon plate as a counter electrode in an aqueous solution containing 5% boric acid and 0.3% sodium chloride. After washing this with water, it was etched in a 5% aqueous sodium hydroxide solution at 50°C for 30 seconds, and then etched with 15% phenolsulfonic acid.
DC 2.5A/dm ² in aqueous solution containing 0.5% sulfuric acid
When electricity was applied for 50 minutes, an uneven pattern with dark and light amber stripes was obtained.

When the colored striped films obtained in Examples 1 to 7 were irradiated with ultraviolet rays for 200 hours using a sunshine weather meter, no change was observed.

As described above, according to the method of the present invention, a film with new commercial value can be obtained by imparting a striped pattern to a colored film that could only be obtained uniformly in the past, and it has also been confirmed that the film has extremely good light resistance.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional view of a barrier layer film produced in the AC electrolysis step of the method of the present invention, and Figure 2 is a partial cross-sectional view of the barrier layer film produced on the barrier layer film of Figure 1 in the anodization and secondary electrolytic coloring steps of the method of the present invention. FIG. 3 is a partial sectional view of a striped colored film formed on the barrier layer film of FIG. 1 in the electrolytic coloring process of the method of the present invention, and FIG. FIG. 5 is a partial cross-sectional view of a striped colored film formed in the anodization and secondary electrolytic coloring steps after the etching process of the method of the present invention; FIG. The figure is a partial sectional view of a striped colored film produced in the electrolytic coloring step after etching in the method of the present invention. 1...Aluminum fabric, 2...Barrier type film, 3...Recessed portion where the film was dissolved, 4...Recessed portion where the aluminum fabric was melted, 5...Anodized film, 6, 6', 6''... Metal precipitates.

Claims (1)

[Claims] 1. Aluminum or its alloy in a weakly acidic or weakly alkaline aqueous solution containing 0.01 to 1% chloride.
Aluminum characterized by forming a striped barrier layer film by alternating current electrolysis at a voltage of 10 to 100 V, and then electrolytically developing color in an organic acid or a solution containing an organic acid and sulfuric acid by a conventional method. or striped coloring method for its alloys. 2 Aluminum or its alloy in a weakly acidic or weakly alkaline aqueous solution containing 0.01 to 1% chloride.
A barrier layer film with a striped pattern is formed by alternating current electrolysis at a voltage of 10 to 100 V, then an anodized film is formed by a conventional method in an acidic aqueous solution, and then an anodic oxide film is formed by a conventional method in an aqueous solution containing a metal salt. A striped pattern coloring method for aluminum or its alloys, which is characterized by electrolytically coloring aluminum or its alloys. 3 Aluminum or its alloy in a weakly acidic or weakly alkaline aqueous solution containing 0.01 to 1% chloride.
A striped barrier layer film is formed by alternating current electrolysis at a voltage of 10 to 100 V, and this barrier layer film is etched in an aqueous sodium hydroxide solution, and then an organic acid or an organic acid and sulfuric acid are added. A striped pattern coloring method for aluminum or its alloy, which is characterized by carrying out electrolytic coloring in a solution using a conventional method. 4 Aluminum or its alloy in a weakly acidic or weakly alkaline aqueous solution containing 0.01 to 1% chloride
A barrier layer film with a striped pattern is formed by alternating current electrolysis at a voltage of 10 to 100 V, this barrier layer film is etched in an aqueous sodium hydroxide solution, and then an anodized film is formed by a conventional method in an acidic aqueous solution. A method for coloring aluminum or its alloy in a striped pattern, which is then electrolytically colored in an aqueous solution containing a metal salt by a conventional method. 5 Chlorides include sodium chloride, potassium chloride, copper chloride, iron chloride, calcium chloride, barium chloride,
5. A method according to claims 1 to 4, in which cobalt chloride, magnesium chloride, nickel chloride, manganese chloride, ammonium chloride, tin chloride and zinc chloride are selected. 6 Weakly acidic or slightly alkaline aqueous solutions have a concentration of 0.1~
Claim 1 consisting of 20% tartaric acid, citric acid, malonic acid, maleic acid, phthalic acid, sulfosalicylic acid, cresyl sulfonic acid, succinic acid, boric acid, carbonic acid, phosphoric acid, particularly their alkali salts or ammonium salts. The method described in paragraphs to 5. 7 Weakly acidic or alkaline aqueous solution is further 0-1%
7. The method according to claim 6, comprising sodium hydroxide.