JPH0674517B2 - Aluminum wood grain pattern forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wood grain pattern such as aluminum or aluminum alloy plate material and extruded profile material (hereinafter referred to as "aluminum material"). In the case of forming the colored film of, the present invention aims to further improve the film properties of the colored film.

[0002]

2. Description of the Related Art In recent years, surface coatings have been applied in the fields of sashes, interior fittings, interior doors, entrance sliding doors, entrance doors, gates, fences, balconies, car gates, stair handrails and entrance pillars, building materials, and furniture. Aluminum materials, which are colored yellow or brown by various methods and have a wood-like feel, have come into widespread use. However, since the surface of the conventional wood-tone colored aluminum material is uniformly colored, when viewed from a distance, a feeling far from that of wood can be obtained, regardless of the distance. .

Therefore, various studies have been carried out on forming a pattern such as a wood grain pattern on the surface of an aluminum material, and many proposals as described below have been made so far. (A) A method of engraving a predetermined engraving line on the surface of an aluminum material using a compaction roll or a press mold. (B) A method of etching the original image by etching the surface of the aluminum material with a chemical by a photoengraving method. (C) A method in which the surface of an aluminum material is partially masked with an appropriate protective material and spraying and baking of a paint, or a chemical dyeing treatment or a coloring treatment of an oxide film is performed. (D) A method of printing a paint or other coloring agent on the surface of an aluminum material by means such as screen printing or transfer printing. (E) A method of sticking a pattern paper or a pattern film on which a wood pattern is printed on the surface of an aluminum material.

However, since the embossing method (A) is a method of strongly pressing an aluminum material with a pair of dies or a molding die, it can be applied only to a plate-shaped aluminum material, and of course, a die or a molding die is manufactured. However, the etching method of (B), the masking method of (C) and the printing method of (D) not only take a lot of time and labor for masking and woodgrain pattern making, but The secondary treatment of is very complicated, and the durability of the pattern forming film is also problematic. In addition, each of these methods, including the pattern paper sticking method of (E), requires special mechanical equipment. Therefore, there is a problem that the processing cost is very high and it cannot be used for a building material having a complicated shape or an aluminum extruded shape material as a fitting material.

In order to solve the above-mentioned problems, the applicant company firstly carried out a surface treatment line (degreasing-etching-desmut-
Anodizing treatment-coloring-sealing-painting-drying) can be incorporated, and a grain pattern forming method for aluminum materials by electrochemical treatment based on a completely different principle from the conventional method has been developed (for example, Japanese Patent Publication No. 54-39224, 55-9959 and 62-15640), this treatment method produces aluminum materials with natural grain similar to that of natural wood and having a clear and corrosion-resistant wood grain pattern with high productivity. You can now get below.

However, in the above-mentioned treatment method, when a long aluminum material is treated in a large aluminum surface treatment line, particularly when a plurality of aluminum materials are suspended in one electrolytic frame, the aluminum materials are inter-framed with each other. It was sometimes found that the wood grain pattern became uneven in some cases, and even within one piece of aluminum material, the pattern was different depending on the part and was uneven.

[0007]

Under the current market situation, the trend toward high-mix low-volume production is increasing, and it is an urgent task to stably form a uniform and even grain pattern. The present invention advantageously responds to the above-mentioned demands, and an object thereof is to propose a method for forming a wood grain pattern of an aluminum material, which can stably obtain a uniform grain pattern even in the production of a large variety of small lots.

[0008]

That is, according to the present invention, an aluminum material is electrolytically treated with an aqueous solution of an acid or an alkali as an electrolytic bath by an alternating current or a power supply waveform having an effect equivalent to this, and is generated during the electrolytic treatment. In the method of forming a wood grain pattern by raising bubbles of hydrogen gas along the surface of an aluminum material, the bath voltage at the start of electrolysis is gradually changed to 10-40 V / min until the final reached bath voltage is reached. It is a method of forming a wood grain pattern of aluminum material.

In the present invention, as an electrolytic bath for forming a grain pattern, any of the known baths disclosed in Japanese Patent Publication No. 54-39224 and the like mentioned above is suitable. As an example, sulfuric acid,
Phosphoric acid, chromic acid, sulfamic acid, boric acid, tungstic acid, selenious acid, phosphomolybdic acid, formic acid, acetic acid,
Propionic acid, butanoic acid, oxalic acid, succinic acid, adipic acid, maleic acid, malonic acid, lactic acid, malic acid, citric acid, phthalic acid, tartaric acid, benzolsulfonic acid, phenolsulfonic acid, sulfosalicylic acid, cresolsulfonic acid and thymol A dilute aqueous solution of one or more acids selected from the group consisting of sulfonic acids, or this aqueous solution containing sodium hydroxide, sodium metasilicate, trisodium phosphate, sodium hydrogen carbonate, sodium metaborate, sodium sulfate, sodium carbonate. , Borax and sodium hydrogensulfate, or an aqueous solution containing any one of the alkaline electrolytes selected from the group consisting of ammonium salts, calcium salts, barium salts, lithium salts and potassium salts of the above acids.

As the electrolysis current, it is important to use an alternating current or a current accompanied by generation of hydrogen gas by a power supply waveform similar to this. Pulses, incomplete rectification, and the like can be cited as those having a power supply waveform similar to alternating current.

When the hydrogen gas bubbles generated on the surface of the aluminum material are raised along the surface by the above treatment, as shown in FIG. 1, the surface of the aluminum material is suspended in the hanging direction. A silver-gray wood grain pattern that extends in the (vertical direction) appears. This treatment produces a beautiful silver-gray grain pattern because the large and small number of hydrogen gas bubbles generated during the electrolytic treatment slightly swing left and right along the surface of the aluminum material and rise from the bottom to the water surface. When this occurs, a large difference in electrolytic action occurs on the surface of the aluminum material between the portion traced by the bubbles and the other portion, and the passage portion of the bubbles has much more pores than the other portions. Is considered to be generated and shines in silver grey, and when actually observing the treated aluminum material with a microscope,
The number of pores was found to be much higher in the part traced by the bubbles than in the other parts, and moreover, it was clearly recessed from the surface than in the other parts.

[0012]

[Function] In the wood grain pattern forming step, a predetermined bath voltage (usually 20 to 40 V) is applied immediately after the start of electrolysis, that is, when the voltage is rapidly increased, the current density becomes non-uniform due to the aluminum material site, and the pattern The shapes and densities are uneven. That is, the electric current is concentrated on a local portion of the aluminum material, and not only the burning occurs, but also the pattern formation on other portions becomes insufficient.

In this respect, according to the present invention, when the voltage was gradually increased, a uniform and beautiful wood grain pattern with good contrast was obtained. That is, in the process of forming a film with different structures on the same surface of the same aluminum material to obtain a wood grain pattern, it takes less time to form the film in the initial stage, and the slower the treatment, the less variation. In addition, the difference in the film structure could be highlighted.

FIG. 2 shows a comparison of current-voltage-time curves according to the conventional method and the method of the present invention. As shown in the figure, in the method of the present invention, the adverse effect in the case of a rapid rise was solved by gradually increasing the applied voltage as compared with the conventional method. It is important to control in the range of 40 V / min. If the rate of rise of the applied voltage after the start of electrolysis is less than 10 V / min, it takes too long to reach a sufficient bath voltage (around 30 V) for film formation, which is not preferable. If the amount exceeds the limit, as in the conventional case, there is a high possibility that a burn will occur or the pattern formation will be insufficient.

Since the surface of the aluminum material treated according to the present invention has a non-uniform structure as described above, when it is subjected to an electrochemical coloring oxide film forming treatment, it is naturally colored in a wood-like shade. A pattern is formed. In other words, in the silver-gray depressions where the pores are concentrated, much more colorant such as metal salt or dye is deposited or attached than in other areas where the pore distribution density is low. Even if it is subjected to the treatment and the coloring treatment, the coloring becomes shaded, and a clear wood grain colored pattern is formed.

The colored oxide film forming treatment suitable for forming a colored wood grain pattern by taking advantage of the surface characteristics of the pretreated aluminum material according to the present invention is as follows. (A) In the coloring step, the object to be treated is subjected to AC electrolysis in an inorganic coloring liquid containing a metal salt. (B) After lightly etching with an aqueous solution of an alkali such as sodium hydroxide or sodium carbonate in the film removing step, and performing anodizing treatment in an electrolytic solution containing an inorganic acid and / or an organic acid in the anodizing step, In the coloring step, alternating current electrolysis is performed in a coloring liquid added with a metal salt. (C) After anodizing treatment in an electrolytic solution containing an inorganic acid and / or an organic acid in the anodizing step, it is further immersed in a solution of an inorganic coloring liquid or a dye added with a metal salt in the coloring step.

FIG. 3 schematically shows an aluminum surface treatment line incorporating the grain pattern forming step of the present invention. In the figure, reference numeral 1 is a framing station, 2 is a degreasing tank, 3 is an etching tank, 4 is a desmut tank, and 5 is an AC electrolytic tank for forming a wood grain pattern. Further, 6 is a film removing tank, 7 is an anodizing tank, 8 is an electrolytic coloring tank, 9 is a sealing treatment tank, 10 is an electrodeposition coating tank, 11 is a baking and drying furnace, and 12 is an out-of-frame place.

[0018]

【Example】

Example 1 An aluminum profile (6063S-T5) was pretreated by a conventional method and then subjected to AC electrolysis in a bath of sodium metaborate 0.2 mol / l and boric acid 3 g / l using stainless steel as a counter electrode. . At this time, the voltage was gradually increased to 25 V at a rate of 30 V / min at the start of electrolysis, and was kept at 25 V for 7 minutes. By this treatment, a uniform silver-gray woodgrain pattern was formed on the surface of the aluminum profile. Then, this was immersed in a sodium hydroxide bath (1 g / l, liquid temperature 60 ° C) for 1 minute, washed with water, and then anodized in a sulfuric acid bath to form an anodized film of about 10 μm. Immersed in an inorganic coloring bath containing ferric ammonium oxalate (60 ° C) for several minutes, and finally subjected to boiling water treatment. As a result, it was pale yellow and the above-mentioned wood grain part was a particularly dark colored white wood pattern. A beautiful aluminum profile was obtained.

Comparative Example 1 Under the same conditions as in Example 1, pretreatment was carried out in the same manner, and then AC electrolysis was performed. At this time, when a bath voltage was applied immediately after the start of electrolysis, the grain patterns became uneven between the objects to be processed, the patterns were uneven within the object to be processed, and further, burnt was locally caused. There was also. Then, even if it was subjected to a coloring treatment, only a finished product far from that of natural wood was obtained.

Example 2 The same aluminum profile as used in Example 1 was pretreated by a conventional method to obtain 0.3 mol / l citric acid and sodium hydroxide.
AC electrolysis was performed in a 10 g / l bath using stainless steel as the counter electrode. At this time, the voltage was gradually increased to 35 V at the rate of 40 V / min at the start of electrolysis, and the voltage was maintained at 35 V for 5 minutes. By this treatment, a uniform silver-gray woodgrain pattern was formed on the surface of the aluminum profile. Then, this was immersed in a sodium carbonate bath (40 g / l, bath temperature 45 ° C) for 2 minutes, washed with water, anodized in a sulfuric acid bath, and then treated with copper sulfate (30
g / l) and sulfamic acid (20 g / l) in a bath containing alternating current electrolysis, and the final boiling water treatment gave a beautiful aluminum profile with a beautiful copper-grained wood grain pattern. Was given.

Comparative Example 2 Under the same conditions as in Example 1, pretreatment was performed in the same manner, and then AC electrolysis was performed. At this time, when a bath voltage was applied immediately after the start of electrolysis, the pattern of wood grains became uneven between the objects to be processed, the patterns became uneven within the object to be processed, and further burnt was locally caused. There was also. After that, even if it was colored, the finish was far from that of natural wood.

Example 3 The same aluminum profile as used in Example 1 was pretreated by a conventional method, and stainless steel was used as a counter electrode in a bath of trisodium phosphate 0.3 mol / l and butanoic acid 5 g / l. AC electrolysis was performed using steel. At this time, the voltage was gradually increased to 20 V at a rate of 10 V / min at the start of electrolysis, and was maintained at 20 V for 10 minutes. By this treatment, a uniform silvery wood grain pattern was formed on the surface of the aluminum profile. Then, this is immersed in an aqueous solution of sodium hydroxide (3 g / l, 60 ° C) for 1 minute, washed with water, and then anodized in a sulfuric acid bath to form an anodized film of about 6 µm, then nickel acetate. When AC electrolysis was performed in a bath containing (20 g / l) and boric acid (5 g / l), and finally boiling water treatment was performed, a beautiful brown brown aluminum profile was obtained.

Comparative Example 3 Under the same conditions as in Example 3, pretreatment was performed in the same manner, and then alternating current electrolysis was performed. At this time, when a bath voltage was applied immediately after the start of electrolysis, the grain patterns were uneven between the objects to be treated, the patterns were uneven within the object to be treated, and local burning occurred. After that, even if it was subjected to further coloring treatment, only a finished product far from the natural wood was obtained.

Example 4 The same aluminum profile as used in Example 1 was pretreated by a conventional method, tartaric acid 0.1 mol / l, sodium carbonate 5 g.
AC electrolysis was performed in a bath of / l using a carbon plate as the counter electrode. At this time, the voltage was set to 40 V at the rate of 35 V / min at the start of electrolysis.
Gradually raised to V and held at 40 V for 5 minutes. By this treatment, a uniform silvery wood grain pattern was formed on the surface of the aluminum profile. Then, this was immersed in a sodium hydroxide bath (5 g / l, 60 ° C) for 1 minute, washed with water, and then anodized in a sulfuric acid bath, and then an inorganic coloring bath containing silver sulfate (60 ° C). When it was immersed in the solution for a few minutes and finally subjected to boiling water treatment, a beautiful brown brown aluminum profile was obtained.

Comparative Example 4 Under the same conditions as in Example 4, pretreatment was carried out in the same manner, and then AC electrolysis was performed. At this time, when a bath voltage was applied immediately after the start of electrolysis, the grain patterns were uneven between the objects to be treated, the patterns were uneven within the object to be treated, and local burning occurred. Even after being subjected to a coloring treatment, the finish was far from that of natural wood.

Example 5 An aluminum plate (1050P-H14) was pretreated by a conventional method and then suspended in a bath of adipic acid 0.3 mol / l and triammonium phosphate 10 g / l, and a platinum plate was placed on the counter electrode. AC electrolysis was carried out. At this time, the voltage is set to 25 at the start of electrolysis.
Gradually increased to 30 V at V / min speed and kept at 30 V for 7 minutes. By this treatment, a silver gray wood grain pattern was formed on the surface of the aluminum plate material. Then, soak it in a sodium carbonate bath (50 g / l, 50 ° C) for 2 minutes, wash it with water,
After anodizing in a sulfuric acid bath, immersing it in an inorganic coloring bath containing ferric ammonium oxalate (60 ° C) for several minutes, and finally boiling water treatment, a beautiful wooden board with a white wood pattern. was gotten.

Comparative Example 5 Under the conditions of Example 5, pretreatment was carried out in the same manner, and then AC electrolysis was performed. At this time, when a bath voltage was applied immediately after the start of electrolysis, the grain patterns were uneven between the objects to be treated, the patterns were uneven within the object to be treated, and local burning occurred. After that, even if it was colored, only a finished product far from natural wood was obtained.

Example 6 The same aluminum profile as used in Example 1 was pretreated by a conventional method and treated with a counter electrode in a bath of an aqueous solution of citric acid 0.3 mol / l and sodium hydroxide 5 g / l. AC electrolysis was performed using stainless steel. At this time, the voltage is set to 2 at the start of electrolysis.
Gradually increased to 35 V at a rate of 5 V / min and held at 35 V for 10 minutes. By this treatment, a uniform silver-gray woodgrain pattern was formed on the surface of the aluminum profile. Then, when this was subjected to AC electrolysis in an inorganic coloring bath containing stannous sulfate, only the wood grain portion was clearly colored. Then, a transparent resin was applied by dip coating to obtain an aluminum profile having a beautiful wood grain pattern.

Comparative Example 6 Under the conditions of Example 6, pretreatment was carried out in the same manner, and then AC electrolysis was carried out. At this time, when a bath voltage was applied immediately after the start of electrolysis, the pattern of wood grains became uneven between the objects to be treated, and the local burning occurred. Even after being subjected to a coloring treatment, the finish was far from that of natural wood.

[0030]

Since the present invention is an electrochemical treatment method, it can be incorporated as a pretreatment for forming a colored oxide film on an aluminum surface treatment line for performing a usual electrochemical treatment. By gradually increasing the voltage at the start, it is possible to form a clear and durable wood grain pattern without fear of irregularity in the pattern shape or density and burning which were feared in the case of a rapid increase.

Further, according to the present invention, it is possible to produce a wide variety of products in a small lot, and therefore, it is possible to provide an aluminum material having a beautiful wood grain pattern in a timely and inexpensive manner for various fittings, building materials, furniture, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in a surface reaction state of an object to be treated according to the present invention.

FIG. 2 is a comparison graph of current-voltage-time curves according to the conventional method and the method of the present invention.

FIG. 3 is a schematic view showing an aluminum surface treatment line incorporating a grain pattern forming step of the present invention.

[Explanation of symbols]

 1 Frame setting place 2 Degreasing tank 3 Etching tank 4 Desmut tank 5 AC electrolysis tank 6 Defilming tank 7 Anodizing tank 8 Electrolytic coloring tank 9 Sealing treatment tank 10 Electroplating coating tank 11 Baking drying furnace 12 Outside frame

Claims (1)

[Claims] 1. An aluminum material is electrolyzed with an aqueous solution of an acid or an alkali as an electrolytic bath by an alternating current or a power waveform having an effect equivalent to this, and bubbles of hydrogen gas generated during the electrolysis are treated with the aluminum material. In the method of forming a wood pattern by raising along the surface, the bath voltage at the start of electrolysis is 10
A method for forming a wood grain pattern of aluminum material, which is characterized by gradually increasing at a rate of -40 V / min.