JPS60197897A - Formation of opaque white anodized film of aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To improve corrosion resistance by dipping Al or Al alloy into a soln. contg. a specific salt such as Ca salt and sufluric acid or electrolyzing the same by the soln. thereof in the 1st stage and dipping the Al or Al alloy in the soln. contg. a material forming a white or gray color by reacting with the resulted product from the salt or electrolyzing the same by the soln. thereof in the 2nd stage which is a post process. CONSTITUTION:Al or Al alloy having an anodized film is treated by the process in the 1st stage then the process in the second stage which is a post process to form an opaque white anodized film of the Al or Al alloy. Or the processes of the 1st stage and the 2nd stage mentioned above are incorporated in the stage of the above-mentioned treatment. The process of the 1st stage is the process to dip the Al or Al alloy into a soln. contg. >=1 salts among Ca salt, Mg salt, Zn salt and Al salt and sulfuric acid or electrolyzing the same by the soln. thereof. The process of the 2nd stage is the process to dip the Al or Al alloy a soln. contg. <=1 materials to form a white or gray color by reacting with the resulted product from the above-mentioned salts in the micropores of the anodized film or electrolyzing the same by the soln. thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an opaque white film in which a white to gray-white substance with excellent surface corrosion properties is produced in the micropores of an anodic oxide film of aluminum or an aluminum alloy.

Conventionally, aluminum or aluminum alloys have been colored by various coloring methods and widely used as building materials, nameplates, vehicles, decorations, and the like. For example, in building materials, the color tone is
Because of the cold metallic feel of amber, gold, and silver colors, there is a demand for aluminum or aluminum alloys colored in warm, pastel tones based on opaque white or grayish white in the building materials industry. Ta.

In order to achieve a pastel tone, it is necessary to obtain a basic opaque white or grayish white color, and for this purpose several opaque whitening surface treatment methods have been proposed as described below.

That is, examples of conventional methods for forming an opaque white anodic oxide film include the following methods.

(1) Aluminum material is electrolyzed with alternating current or direct current.

Or after whitening the surface by immersion etc.

A method of performing ordinary anodic acid film treatment (for example, 2 Japanese Patent Publication No. 40-28921, 41-1523) (2) A method of obtaining an opaque white anodic oxide film by the following electrolytic method (for example, Ematal method, Japanese Patent Publication No. 54-1983) 28147.54-28
148) (3) A method for obtaining an opaque white anodic oxide film by performing secondary electrolysis after anodizing film treatment (Japanese Patent Publication No. 14519/1983, No. 54-11248, Japanese Patent Publication No. 50-37631) However, these methods This method has the following drawbacks. In other words, are the chemicals used expensive?

The solution may be harmful, the solution may be unstable, the bath voltage may be high, or the degree of opaque whitening obtained may be insufficient for practical use. Therefore, the current situation is that the problem is dealt with by painting methods.

As a result of research on a method for coloring aluminum or aluminum alloy to a color tone based on opaque white or grayish white, the present inventor found that as a means to obtain the basic opaque white or grayish white color, an anodic oxide film was formed using the following method. It has been discovered that it is extremely effective to produce a white to grayish white substance in the pores.

That is, in the first step, aluminum or an aluminum alloy having an anodized film is immersed in a solution containing a specific salt such as a calcium salt and sulfuric acid, or electrolyzed in the solution, thereby converting the product from the salt into an anodized film. After entering the fine pores of the salt, in the second step of the post-process, the aluminum is immersed in or electrolyzed with a solution containing a substance that reacts with the product from the salt to form a white or off-white compound. Alternatively, an anodic oxide film of an aluminum alloy can generate white or grayish white substances in its micropores at a higher concentration than ever before.

Furthermore, we have discovered that the film has excellent corrosion resistance. Regarding corrosion resistance, the component sulfuric acid is effective, and its effect will be shown in the comparative test results of Examples and Comparative Examples described below.

Here, the term "product from the salt" refers to a compound containing the metal of the salt, the metal, or the salt itself, and is used in this sense in the present invention, including the claims. The concentration of the white to off-white product obtained in the micropores is compared with that of the conventional anodic oxide film as the white concentration of the final anodic oxide film, and is shown in the following table. Its degree of whiteness is extremely good, comparable to that of ordinary white paint or white ceramics.

◎Very good, ○Good, Slightly poor × Not white (metallic color) To explain the present invention in more detail, aluminum or aluminum alloy with an anodized film is treated with calcium salt or magnesium salt in the first step.

Direct current electrolysis, alternating current electrolysis,
By electrolyzing with a waveform having an effect equivalent to direct current or alternating current, the products from the salt enter the micropores of the anodic oxide film and are eliminated.

Here, the waveform that has the same effect as direct current or alternating current is:
For example, waveforms include pre-AC/DC, DC or AC intermittent waves, PR waves, pulse waves, incompletely rectified waves, etc., and also include waveforms that are combinations of these.

During electrolysis using the above waveform, the voltage is changed.

This also includes the so-called current recovery method.

In the second step of the subsequent process, it is immersed in or electrolyzed with a solution containing one or more substances that react with the product from the salt to form a white to off-white compound. The substance that reacts with the product from this salt to form a white to off-white compound is
The main ones are, for example, the following substances. No selection.

Examples of inorganic substances include inorganic acids such as sulfuric acid, phosphoric acid, phosphoric acid, hydrochloric acid, butic acid, and sulfamino acid, and alkali salts and ammonium salts of the above-mentioned inorganic acids such as sodium phosphate, sodium fluoride, and ammonium.

Alkali hydroxides such as caustic soda and caustic potash, soda carbonate, alkali carbonates such as potassium carbonate, sodium metasilicate, sodium orthosilicate, trisodium phosphate, sodium stannate, potassium stannate, metasulfuric acid These include alkalis having acid groups such as Noda and sodium pyrophosphate, and other ammonia water.

Organic substances include aliphatic acids such as citric acid and acetic acid.

Salts of the aliphatic acids such as ammonium oxalate, amines such as monoethanolamine, jetanolamine, triethanolamine, aliphatic sulfonic acids such as ethylsulfonic acid, aromatic acids such as benzoic acid, cresol sulfone acid, phenol sulfonyl k + F luenesulfonic acid,
These include aromatic sulfonic acids such as sulfosalicylic acid.

In the case of organic substances, some derivatives and substituted substances of the above-mentioned substances act in a similar manner. By immersion in or electrolysis with a solution containing one or more of these substances, those substances react with the products from said salts that have entered the micropores during the first stage of immersion or electrolysis, producing a white color. A to grayish-white compound is produced in the micropores, and if necessary, post-processes such as puncturing and drying are carried out using conventional methods. The electrolysis waveform in this case is processed by applying the same waveform as in the first stage.

Now, the calcium salt used in the first step of immersion or electrolysis is, for example, calcium oxalate.

These include calcium chloride, calcium acetate, calcium bromide, and calcium iodide. Magnesium salts include, for example, magnesium oxalate, magnesium chloride, magnesium acetate, magnesium bromide, magnesium iodide, and magnesium sulfate. Examples of zinc salts include zinc sulfate.

Zinc oxalate, zinc chloride, zinc acetate, zinc bromide.

Cedar with zinc iodide etc. Examples of aluminum salts include aluminum sulfate and sodium aluminate.

These include aluminum phosphate, aluminum chloride, and aluminum oxalate.

Further, in the first step, the concentration containing the salt is about ly/
1 to saturated liquid, preferably about 10 to 50 f/l. The 1 degree of sulfuric acid is about 52% or less, and if it exceeds this, a precipitate will form in the solution and good whitening of the anodic oxide film will not be obtained. The conditions for immersion in this solution are about 1 liter
O~80C1 preferably about 40~60C2 hours is about 1~
50 minutes, preferably about 10-30 minutes.

In the case of a DC IT solution, the electrolytic conditions are: aluminum or aluminum alloy is used as the cathode, and the voltage is about 5 to 50 cm, preferably 1.
Specifically, it is about 10 to 25v.

The liquid temperature is about 1 to 50 C, preferably about 15 to 30 C, and the time is about 30 seconds to 30 minutes, preferably about 3 to 10 minutes.

In the case of AC electrolysis, the voltage and liquid temperature for 2 hours are the same as in the case of DC electrolysis.

Further, the solution containing the substance used in the second step has a concentration of the substance of about 0.5 to 2007/l, preferably about 1 to 50 y/t.

Immersion conditions are liquid temperature of about 15 to 30 C2, preferably about 30 to
60C5 time is about 30 seconds to 50 minutes.

Preferably it is about 10 to 30 minutes.

In the case of direct current electrolysis, the electrolytic conditions are: aluminum or aluminum alloy is used as the cathode, voltage is about 5 to 40V, preferably about 10 to 30V, liquid temperature is about 15 to 30C, preferably 20 to 30C, 9 hours is about 30V. seconds to 20 minutes, preferably about 3 to IO minutes. In the case of AC electrolysis, the voltage and liquid temperature for 7 hours are the same as in the case of DC electrolysis.

Furthermore, in the present invention, the first stage liquid conditions (liquid composition, pH, liquid temperature, etc.), immersion conditions (liquid composition, liquid temperature for 9 hours, etc.), and electrolytic conditions (current).

9 hours of voltage, waveform, etc.), it is sufficient that the substance penetrates deeper and more into the micropores, and the form of the substance in the micropores does not need to be specified in a narrow range, so the conditions can be varied over a wide range. The advantage is that you can choose from. In addition, the liquid conditions and treatment conditions (electrolytic conditions, immersion conditions) in the second stage are basically based on the chemistry between the substance in the micropores and the liquid components.

Since it is only necessary that the electrochemical reaction is sufficiently carried out to produce a white to off-white insoluble compound, the conditions can be selected from an extremely wide range. In theory, there are combinations suitable for the first and second stages, but as mentioned above, there are many optimal combinations due to the wide selection range.

I cannot describe them all here.

It can be easily determined experimentally by one skilled in the art.

In addition, various additives such as pH buffers, surfactants, etc. can be added to each of the first and second stage solutions.
By adding a reaction accelerator 9, a reaction inhibitor, etc., various properties such as white to gray-white production efficiency and solution stability can be improved.

What is noteworthy about the present invention is that by combining it with various already known aluminum coloring methods, pastel-like coloring based on opaque white to grayish white can be obtained.

Examples of combinations of the coloring process and the aluminum coloring method that can be employed in the present invention are shown in the following table.

A: Alloy coloring method (Japanese Patent Publication No. 16341, etc.) B: Electrolytic coloring method (Calcolor method, etc.) C: Electrolytic coloring method, multi-stage electrolytic coloring method (Japanese Patent Publication No. 38-171)
5. (Japanese Patent Publication No. 49-67043, etc.) D = Inorganic or organic immersion coloring method, inorganic alternate immersion coloring method 9 As shown in this table, the present invention can be combined with many coloring methods, thereby creating an opaque white or gray-white color. Warm pastel colors such as cream and beige.

It is possible to provide aluminum or aluminum alloy coloring materials that meet market demands such as eye poly color and cherry color. The present invention makes it easy and practical to realize warm, pastel colors by combining various coloring methods for aluminum or aluminum alloys with the present invention. It is clearly stated here that the present invention is basically applied or utilized in all combination methods, even if the process steps of the combination are different, and the present invention is used in all cases. do.

Nine embodiments of the present invention will be described below. All of these examples are examples of applying the present invention to create an opaque colored film, but 2 will mainly describe the parts related to the present invention, and 9 will omit ordinary pre-treatments, post-treatments, etc.

Example 1 After pretreatment of degreasing, etching, and smut removal, an aluminum plate of AIlooP was heated at a current density of 1.5 A/in a 15% 0 sulfuric acid aqueous solution <yyc>.
Apply direct current electrolysis at DM2 for 30 minutes to form an anodized film.

Then calcium acetate 3 Ofl/l and sulfuric acid 0.5
f/l aqueous solution (30tZ') at an AC voltage of 20V.
After electrolyzing for a minute and washing with water, an aqueous solution of 302/l of cynic acid (30
In step C), electrolysis was performed at an AC voltage of 20 V for 10 minutes to obtain an opaque white film on the surface of the aluminum plate.

Example 2 After pre-treating the aluminum plate of AIlooP by degreasing, etching, and removing smut, it was treated with a 15% sulfuric acid aqueous solution (fl
An anodized film was applied by direct current electrolysis at a current density of 1.5 A/dm2 for 30 minutes in 1J C).

After that, it was immersed for 20 minutes in an aqueous solution (60C) of aluminum sulfate soy/t and sulfuric acid 0.5f/l,
After washing with water, add 20 to 7' of phosphoric acid to an aqueous solution (40C).
After dipping for a minute, an opaque white film was obtained on the surface of the aluminum plate.

Example 3 An anodized film was applied to an aluminum plate of Al100P in the same manner as in Example 1, and then electrolyzed with an aqueous solution (25C) of 10ii'/l of zinc sulfate and 0.25 J/l of sulfuric acid at an AC voltage of 20V for 5 minutes. , after washing with water.

DC voltage 1 with an aqueous solution (25C) of 20 g/l of citric acid
Electrolysis was performed at 5V for 20 minutes to obtain an opaque grayish-white film on the surface of the aluminum plate.

Example 4 An anodic oxide film was applied to an A6063 aluminum extrusion in the same manner as in Example 1, and then calcium acetate 20
? /l and an aqueous solution (60C) of sulfuric acid o5y/l.
After soaking for a minute and rinsing with water.

AC voltage 20 at 30 y/l aqueous solution (35C) of sulfuric acid
Electrolysis was carried out at V for 20 minutes to obtain an opaque white film on the surface of the aluminum extrusion.

Example 5 An anodized film was applied to an aluminum plate of AIlooP in the same manner as in Example 1, and then selenite 7-da 5f/l was applied.
and an aqueous solution (30C) of sulfuric acid t sy / l at an AC voltage of 15 V for 1 minute to color it gold, and after washing with water, magnesium sulfate 3 oy / l and sulfuric acid 0.59
/l aqueous solution (60C) for 20 minutes, and after washing with water,
AC voltage 2 with an aqueous solution (AOTL) of 30 fI/l phosphoric acid
Electrolysis was performed at 0 V for 20 minutes to obtain an opaque cream-colored film on the surface of the aluminum plate.

Example 6 An anodized film was applied to an aluminum plate of AIlooP in the same manner as in Example 1, and then calcium acetate l O? /
1 and an aqueous solution (25 C) of sulfuric acid 059/l at a DC voltage of 15 V for 2 minutes.

After washing with water, aqueous solution of trisodium phosphate ao y/t 4
An opaque white film was obtained on the surface of the aluminum plate by immersion at 0C for 20 minutes.

Example 7 An anodic oxide film was applied to an aluminum plate of A 1100 P in the same manner as in Example 1, and then 30 Iil/l of Magne/Lum oxalate and 0.5 ml of sulfuric acid were applied. /l aqueous solution (30
G) was electrolyzed at an AC voltage of 20 V for 5 minutes, washed with water, and then immersed in an aqueous solution (40 C) of 301/l of soda carbonate for 20 minutes to obtain an opaque white film on the surface of the aluminum plate.

Example 8 An anodic oxide film was formed on the aluminum plate of AIlooP in the same strip as in Example 1, and then an AC voltage of 15 was applied with a colored solution (25 C) of 47/l of stannous sulfate and 151/l of sulfuric acid.
v for 3 minutes to color it in olive color. After washing with water, electrolyze with an aqueous solution (30iC) of calcium acetate 10f/t and sulfuric acid O, 5y7t for 5 minutes at AC voltage 20V. After washing with water, use trisodium phosphate 109/t. l aqueous solution (40tZ'
) for 20 minutes to obtain an opaque beige film on the surface of the aluminum plate.

Example 9 An anodic oxide film was applied to an aluminum plate of Al 100 P in the same manner as in Example 1, and then 5% of sodium selenite was applied.
Electrolyzed with an aqueous solution (25C) of 2/l and 15 y/l of sulfuric acid at an AC voltage of 15 V for 3 minutes to give it a gold color. After washing with water, 10 g/l of magnesium sulfate and 1. or/l
Electrolyze with an aqueous solution (30C) at an AC voltage of 20V for 5 minutes,
After washing with water, add 20 ml of silicic acid loy/l aqueous solution (40 IC).
An opaque cream-colored film was obtained on the surface of the aluminum plate by dipping for a minute.

Example 1O An anodized film was formed on an aluminum plate of AIlooP in the same manner as in Example 1, and then Alumalite Gold 108
(dye made by Kaname Shokai) 25y/l dye bath (50
C) was crushed for 5 minutes, colored gold, washed with water, and then treated with an aqueous solution of 10 f//l aluminum sulfate and sulfuric acid o, sy/z' (
3otT) for 5 minutes at an AC voltage of 20V, and after washing with water,
An opaque cream-colored film was obtained on the surface of the aluminum plate by immersion in an aqueous solution (40 tl) of 30 f//l of sodium carbonate for 20 minutes.

Example 11 After pre-treating the aluminum plate of AIlooP by degreasing, etching, and removing smut, sulfosalicylic acid too
r/z, sulfuric acid o, sy/t aqueous solution (20C)
Anodic acid was electrolyzed with direct current for 30 minutes at a current density of 3 A/dm2 to produce a pale fluorine color.
Then, 102/l of magnes/lum sulfate and 0.5 sulfuric acid
y/t aqueous solution (30C) at AC voltage 20V 5
After electrolyzing for a minute and washing with water, add 20% phosphoric acid. /l aqueous solution (4
0C) for 20 minutes to form an opaque beige film on the surface of the aluminum plate.

Example 12 The opaque white film obtained in Example 7 was coated with nickel acetate 37
By sealing the pores with an aqueous solution of 95 iC or higher containing 1/1 or higher, an opaque film colored in pale green was obtained.

Example 13 A yellow anodic oxide film was applied to an A5052 aluminum plate in the same manner as in Example 1, and then.

Electrolyze with an aqueous solution (301Z") of 109/l of calcium acetate and 052/l of sulfuric acid at an AC voltage of 20 V for 5 minutes, and after washing with water, add 2
After immersion for 0 minutes, an opaque cream-colored film was obtained on the surface of the aluminum plate.

Example 14 The opaque white film obtained in Example 1 was washed with water.

After washing with hot water and treating with acrylic-melamine as the main component, it was fired to obtain an opaque white composite film.

Example 15 After washing the opaque white film obtained in Example 1 for 7 years, an opaque cream-colored film was obtained on the surface of the aluminum plate.

Example 16 An anodic oxide film was applied to an aluminum plate of A 1100 P in the same manner as in Example 1, and then 2 t/m of calcium acetate was applied.
l and sulfuric acid 0.5 f//t aqueous solution (30C)
Electrolyze at AC voltage 20V for 5 minutes.

After washing with water, sulfuric acid 15g/1, sodium selenite 5y
AC voltage 15V power "1" with an aqueous solution (25C) containing /t
After electrolyzing for a minute and washing with water, add 20% phosphoric acid. /l aqueous solution (
40C) for 15 minutes to form an opaque white film on the surface of the aluminum plate.

Example 17 An anodized film was applied to an aluminum plate of AI 100P in the same manner as in Example 1, and then calcium acetate 10 f/
1 and an aqueous solution (25) of 0.5 Y/l of sulfuric acid at a DC voltage of 15 V for 1 minute.

After washing with water, an aqueous solution of 10 f/l of ferric ammonium oxalate (50
1 for 10 minutes, and after washing with water, add 30ii'/l of soda carbonate.
An opaque pale yellow film was obtained on the surface of the aluminum plate by immersing it in an aqueous solution (40C) for 15 minutes.

Example 18 A 1100P aluminum plate was anodized in the same manner as in Example 1, and then calcium acetate 20y/
1 and an aqueous solution (30C) of 0.5 f//l of sulfuric acid at a DC voltage of 15 V for 1 minute.

After washing with water, electrolysis was carried out in an aqueous solution of sodium selenite SV/l and sulfuric acid 15 g/l (3011f AC voltage 18 Vf for 20 minutes to obtain an opaque cream-colored film on the surface of the aluminum plate.

Comparative Example An opaque white film was obtained on the surface of an aluminum plate in the same manner as in Example 1 except that sulfuric acid o5y7't was not used.

One sample was prepared for each of Example 1 and Comparative flJ, and the erodibility (JISH8681
, alkali resistance test, and Cath resistance test (8 hours R-N), and the test results (average values) are shown in the table below.

As is clear from this table, the opaque white film obtained by the present invention has improved mono-corrosion resistance.

The opaque colored film obtained in the present invention can be improved in terms of durability by a conventional sealing treatment or by various clear coatings (electrodeposition, electrostatic, dipping, coating, etc.).

Claims (1)

[Claims] Aluminum or aluminum characterized by treating aluminum or an aluminum alloy having an anodized film in the following two steps A and B, or including at least two steps A and B. A method for producing an opaque white anodic oxide film on alloys. A Step of immersing in or electrolyzing with a solution containing one or more salts of calcium salt, magnesium salt, zinc salt, and aluminum salt and sulfuric acid B. In a subsequent step, formation from the salt in the micropores of the anodic oxide film A process of immersion in or electrolysis with a solution containing one or more substances that react with substances to form white or off-white compounds.