JPS621480B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method for patterning aluminum, in which patterning and electrolytic coloring are performed in the same bath.

In this specification, aluminum is a general term for aluminum and aluminum alloy materials.

Conventionally, as a method of creating patterns on the surface of various types of aluminum for building materials and furniture, which have complex cross-sectional shapes, a water-soluble thin film such as polyvinyl alcohol, on which the desired pattern is printed with an electrolytic coloring inhibitor, has been used. , float the aluminum on the liquid surface with the pattern printed side facing up, then submerge the aluminum into the liquid while pressing the printed side, and use the liquid pressure to adhere the thin film to the aluminum surface, thereby making the pattern on the aluminum surface. After that, the thin film is removed with hot water and then colored in a separately prepared electrolytic coloring bath.

This conventional method requires separate transfer baths and electrolytic coloring baths, which has drawbacks such as an increase in the scale of the entire facility, high power consumption, and complicated process management.

This invention aims to eliminate the above-mentioned drawbacks, and focuses on the fact that thin films swollen by water have weak electrical insulation properties and have the property of permeating metal ions. This method is characterized in that electrolytic treatment is performed subsequent to deposition, thereby providing an innovative surface treatment method that not only allows steps to be omitted, but also reduces equipment and power consumption required.

This will be explained in more detail below. First, the aluminum to which the thin film is attached and the printed pattern is transferred has an uncolored anodic oxide film and a colored anodic oxide film formed on it. To generate a positive oxide film in a non-colored state, after pre-treatment such as degreasing, washing, etching, and removing smut by conventional methods, a porous oxide film such as sulfuric acid, oxalic acid, sulfuric acid-oxalic acid mixed acid, etc. is applied. In the bath that generates
Perform electrolytic treatment using DC electrolysis, AC electrolysis, AC/DC superimposed electrolysis, or other current waveforms that have equivalent effects.

In addition, this anodic oxide film can be treated with orthophosphoric acid, pyrophosphoric acid, phosphorous acid, chromic acid, sulfuric acid,
Baths mainly consisting of high concentration sulfuric acid of 40V/V% or more or one or more inorganic acids of these salts, -OH such as malic acid, maleic acid, citric acid, tartaric acid, sulfosalicylic acid, gallic acid, etc. group or -
Direct current, alternating current, or a combination of these is immersed in a bath mainly containing one or more of various organic acids containing COOH groups or their salts, or a bath containing an appropriate mixture of these inorganic acids and organic acids. Similarly, the micropore structure of the anodic oxide film can be changed by carrying out current treatment using a waveform in which positive and negative polarities are alternately changed, or an AC/DC superimposed waveform.

Such treatment has the advantage that during the subsequent electrolytic coloring process, a colored film with a variety of tones can be produced, which is different from when a normal anodic oxide film is subjected to electrolytic coloring.

Although the above-mentioned anodic oxidation treatment does not involve any coloring effect, coloring can be caused when the anodic oxide film is formed by changing the bath composition.

In addition, a non-colored anodic oxide film that does not develop color can be made into a colored film by performing any of the following treatments.

(1) In a coloring bath mainly composed of acids or salts of various metals involved in coloring nickel, cobalt, copper, tin, manganese, etc., use appropriate current waveforms such as AC electrolysis, DC cathode electrolysis, or AC/DC superimposed electrolysis. A method of applying electrolytic coloring treatment.

(2) A method of coloring by dipping in dye.

As mentioned above, an electrolytic coloring inhibitor is transferred to a colored (including coloring and dyeing) anodic oxide film of aluminum or an uncolored anodic oxide film. Here, what is an electrolytic coloring inhibitor? It is a substance that inhibits electrolytic coloring treatment, and does not conduct electricity during the treatment, or because of the nature of the substance, it inhibits the coloring action itself and makes it difficult for metals etc. to precipitate into the micropores of the anodic oxide film. be.

Examples of the former include insulating substances such as kaolin, dibutyl phthalate, acetate, glycerin, ethylene glycol, higher fatty acid esters, resist inks, oil-based dyes, and various synthetic resins; Substances that generate sodium ions, nitrate ions, potassium ions, and ammonium ions are used, specifically, sodium hydroxide, potassium hydroxide,
Examples include aqueous solutions such as aqueous ammonia, nitric acid, sodium nitrate, sodium sulfate, ammonium sulfate, and potassium sulfate, and pastes thereof.

The printing methods used to print the above-mentioned electrolytic coloring inhibitor in a patterned thin film include screen printing, offset printing, and gravure printing. synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, methyl cellulose, carboxymethyl cellulose, and acrylamide; examples of animal polymers include glue, gelatin, casein, and Examples of vegetable polymers include starch, cellulose, dextrin, soybean protein, and agar.

As mentioned above, the thin film printed with electrolytic coloring inhibitors in a pattern adheres to the aluminum surface using hydraulic pressure. After floating the aluminum, the aluminum is submerged in the liquid while being pressed against the printing surface, so that the thin film submerged in the liquid adheres to the entire surface of the aluminum. It works effectively when it has a cross-sectional shape.

In particular, in this invention, this liquid pressure is utilized in an electrolytic coloring bath.

In order to bring the thin film into close contact with the electrolytic coloring bath and to adhere and transfer the electrolytic coloring inhibitor to the aluminum surface, it is necessary that the aluminum surface be in a dry state.

If work efficiency and cost are not considered, it is possible to dry the aluminum by natural drying or forced drying in a drying oven, but in consideration of both work efficiency and cost savings, it is preferable to wash aluminum with hot water.

However, in general, when an anodic oxide film is washed with hot water, the pores become sealed and are not colored in the subsequent electrolytic coloring process.

On the other hand, as mentioned above, when the anodized film is energized in a bath containing a specific chemical such as orthophosphoric acid or an organic acid containing -OH or -COOH groups, the fine pores of the anodized film are Due to the structural changes, the properties of the anodic oxide film have been changed to make it less likely to be sealed, and it can be colored by electrolytic coloring even after hot water washing.

In this way, the thin film of the electrolytic coloring inhibitor floating on the surface of the electrolytic coloring bath and the aluminum that has formed a colored or non-colored anodic oxide film on the printed surface are pressed down and submerged in the electrolytic coloring bath, and the thin film is made of aluminum. By bringing it into close contact with the surface, the electrolytic coloring inhibiting substance is brought into close contact with the surface of aluminum.
In this case, it can also be attached to the surface of aluminum.

At this point, the thin film is impregnated with the electrolytic coloring bath liquid and swells, making it easy for metal ions in the electrolytic coloring bath to pass through when electricity is applied, so electrolytic coloring can be performed while the thin film remains in close contact. Only the parts to which the electrolytic coloring inhibitor is not attached are colored.

A summary of the processing steps up to this point is as follows.

(1) Electrolytic treatment is applied to the anodic oxide film (non-colored) in an electrolytic coloring bath while the thin film remains in close contact.
(Applicable to Example 1) At this time, the areas in close contact with the electrolytic coloring inhibitor remain as non-colored anodic oxide films, and the other non-adherent areas are colored.

(2) Electrolytic treatment is applied to the colored anodic oxide film in an electrolytic coloring bath while the thin film remains in close contact with the film. (Applicable to Example 2) At this time, the areas in close contact with the electrolytic coloring inhibitor remain in a colored state, and the other non-adherent areas have a composite color tone of the color tone of the developed color and the color tone of the electrolytic coloring.

(3) Electrolytic treatment is applied to the dyed anodic oxide film in an electrolytic coloring bath while the thin film remains in close contact with the dyed anodic oxide film.
(Applicable to Example 3) At this time, the areas in close contact with the electrolytic coloring inhibitor remain in the dyed color tone, and the other non-adherent areas have a composite color tone of the dyed color tone and the electrolytic coloring tone.

(4) The anodic oxide film (non-color forming) is coated with orthophosphoric acid,
Electrolytic treatment is performed in a bath containing an organic acid containing -OH or -COOH groups as a main component to change its micropore structure, and the thin film is left in close contact with this anodic oxide film in an electrolytic coloring bath. Electrolytic treatment is performed in this condition. (Applicable to Example 4) At this time, the areas in contact with the electrolytic coloring inhibitor remain as non-colored anodic oxide films, and the other areas not in contact are colored in various tones.

(5) After the anodic oxide film (non-colored) is treated as in (4) above to change its micropore structure, it is electrolytically treated in a primary electrolytic coloring bath containing a metal acid or salt as its main component. This primary colored anodic oxide film is electrolytically treated in a separate secondary electrolytic coloring bath with a thin film in close contact with the anodized film. (Applicable to Example 5) At this time, the areas in close contact with the electrolytic coloring inhibitor remain the primary coloring tone, and the other non-adherent areas become a composite color tone of the primary coloring tone and the secondary coloring tone. .

In this way, it is possible to generate a colored pattern on the surface of aluminum based on the difference between the areas where the electrolytic coloring inhibitor is adhered and the areas where it is not.

The aluminum that has undergone the electrolytic coloring treatment is pulled out of the coloring bath, and the swollen thin film is removed from the surface of the aluminum by suitable means such as hot water washing or shower spraying.

Although it is preferable to remove the electrolytic coloring inhibiting substance attached to the surface of the aluminum, it is not necessary to remove it as long as it is transparent, since it will not have an adverse effect on pattern formation.

In this case, since the removal process can be omitted, it is possible to reduce equipment costs, facilitate process management, and improve work efficiency.

As described above, since the present invention is characterized in that the adhesion treatment and electrolytic coloring treatment of the thin film are performed in the same electrolytic coloring bath, different treatment tanks may be installed for each treatment. It is possible to achieve remarkable effects compared to conventional methods, such as shortening processing time, saving power, reducing factory scale, and simplifying process management.

Examples of the present invention are as follows.

Example 1 An aluminum plate A1200P was immersed in 10wt% nitric acid to be degreased and cleaned, and then immersed in 5wt% sodium hydroxide at a bath temperature of 50°C for 8 minutes to perform etching treatment. Next, after removing smut by immersing it in 10 wt% nitric acid, it was anodized in a 15 wt% sulfuric acid bath at 20°C at a current density of 1.0 A/dm ² for 30 minutes.

On the other hand, a polyvinyl alcohol thin film screen-printed with a transparent resin made of butyl phthalate and epoxy resin in a floral pattern was coated with nickel sulfate 50.
The dry aluminum plate, on which the anodic oxide film was formed by floating it on the liquid surface of a coloring bath consisting of 50g/g/ and boric acid, was submerged in the coloring bath, and the thin film was brought into close contact with the liquid by hydraulic pressure. Then, after electrolyzing the thin film in contact with the aluminum plate in the coloring bath at 25 volts DC for 2 minutes, the thin film was dissolved and removed with hot water at 30°C, and the parts of the flower pattern that were in contact with the electrolytic coloring inhibitor became silver. A bronze colored pattern was generated in other non-adhesive areas.

Example 2 Example 1 on aluminum alloy A6063S extruded material
After the same pretreatment as above, sulfosalicylic acid
100g/, sulfuric acid 10g/20 connected to the anode in the bath
℃ and a current density of 2.0 A/dm ² for 45 minutes to form a brown anodic oxide film.

On the other hand, a thin methylcellulose film made of a transparent resin made of butyl carbitol and an alkyd resin was offset printed in a wood grain pattern,
, 10 g of sulfuric acid and 10 g of sulfosalicylic acid were floated on the surface of a coloring bath, and the thin film was brought into close contact with the surface of the extruded shape in a dry state on which a brown film had formed, using hydraulic pressure, and then, A. With the thin film still in close contact with the extruded shape in the coloring bath.
C. After electrolytic treatment at 20 volts for 7 minutes, the thin film was dissolved and removed with hot water at 40°C, and the areas where the electrolytic coloring inhibitor adhered to the woodgrain pattern were brown, and the other areas were colored black.

Example 3 After subjecting aluminum A1200P to the same pretreatment and anodizing treatment as in Example 1, it was immersed in 10 g of ferric ammonium oxalate/bath for 3 minutes at a bath temperature of 65°C to form a pale golden colored film. I let it happen.

On the other hand, a thin film made of methylcellulose screen-printed with transparent acrylic resin paint in a polka dot pattern,
Floating on the liquid surface of a coloring bath consisting of 20 g of copper sulfate and 7 g of sulfuric acid, the thin film was brought into close contact with the surface of the dry aluminum plate on which the pale golden film had been formed using liquid pressure, and the coloring bath was After electrolyzing the thin film in close contact with the aluminum plate for 3 minutes at AC 15 volts in a chamber, the thin film was dissolved and removed with 40°C hot water, and the polka-dot pattern of areas in contact with electrolytic coloring inhibitors turned light golden yellow. A red colored pattern was generated in the non-adherent area.

Example 4 Example 1 on aluminum alloy A6063S extruded section
After performing the same pretreatment and anodic oxidation treatment, connect it to the anode in a bath of 100 g of phosphorous acid and adjust the bath temperature.
Electrolytic treatment was performed for 2 minutes at 20°C and 20 volts DC to change the micropore structure of the anodic oxide film. Then, after immersing it in pure water at 80℃ for 5 minutes, it was heated to 100℃.
Drying was carried out for 2 minutes in an atmosphere of

On the other hand, a resin paint consisting of butyl carbitol, precipitated barium sulfate, and alkyd resin was floated on the surface of a coloring bath consisting of 20 g of manganese sulfate and 20 ml of hydrogen peroxide. Then, using hydraulic pressure, the thin film was brought into close contact with the surface of the extruded aluminum shape with a changed micropore structure, and then the thin film was brought into close contact with the extruded shape in the coloring bath.
After electrolytic treatment at 40 volts DC for 2 minutes, 40℃
When the thin film was dissolved and removed with hot water, the wood-grain pattern-like areas that had adhered to the electrolytic coloring inhibitor remained silver, while the other areas that had not adhered formed ocher-colored patterns.

Example 5 After subjecting an aluminum alloy A6063S extruded shape to the same pretreatment and anodizing treatment as in Example 1, it was connected to an anode in a bath of 100 g of phosphorous acid and heated to a bath temperature of 20
Electrolytic treatment was performed for 3 minutes at ℃ and 10 volts DC. Next, this aluminum alloy was treated with stannous sulfate.
10g/, sulfuric acid 10g/, sulfosalicylic acid 10g/
In a primary coloring bath consisting of
Electrolytic treatment was performed for 1 minute under volt conditions to produce a wine red colored film, and then immersed in a 0.1 g/triethanolamine aqueous solution at 70°C for 10 minutes.
It was left to dry in an atmosphere at ℃ for 3 minutes.

On the other hand, a polyethylene oxide thin film with a transparent acrylic resin paint gravure-printed in a wood grain pattern was floated on the surface of a secondary coloring bath having the same composition as the above-mentioned primary coloring bath, and the aluminum extrusion produced the above-mentioned wine red colored film. The above thin film is brought into close contact with the surface of the shape using hydraulic pressure, and A.
C. After electrolytic treatment at 20 volts for 3 minutes, the thin film is dissolved and removed with hot water at 40°C, and the aluminum extruded shape has a wood-grain colored pattern in which the areas in contact with the electrolytic coloring inhibitor are wine red and the other areas in contact are black. produced uniformly.

Claims (1)

[Claims] 1 A desired pattern made of an electrolytic coloring inhibitor was printed on a thin film made of a substance that does not generate sodium ions upon hydrolysis, and this thin film was floated on the surface of an electrolytic coloring bath to produce a colored or non-colored anodic oxide film. The thin film is brought into close contact with the surface of dry aluminum using liquid pressure, and the thin film is electrolytically colored in an electrolytic coloring bath while the thin film remains in close contact with the surface of the aluminum, and then the thin film is removed from the surface of the aluminum. 1. A patterned surface treatment method for aluminum, characterized in that a colored pattern is generated based on the difference between a portion in close contact with an electrolytic coloring inhibitor and a portion not in close contact with the substance.