KR20100085704A - Method on surface treatment of aluminium material - Google Patents

Abstract

PURPOSE: A surface processing method of high intensity aluminum alloy is provided to reduce manufacturing costs by not applying primer agent by directly inkjet printing dye on a film formed by an anodizing process. CONSTITUTION: A surface processing method of high intensity aluminum alloy comprises the following steps. An aluminum alloy material after finishing a micro pinning process and a mechanicals surface polishing process is anode oxidized. A porous film layer is created. Ink is injected into the porous film layer of the aluminum alloy material which is the cathode oxidation process through the inkjet printing. The surface of the aluminum alloy material is colored. The porous film layer of the aluminum alloy material inserted the ink is sealed. The sealed aluminum alloy material is polished. A cathode oxidation process is processed in sulfuric acid solution in 0~25°C.

Description

Method on surface treatment of aluminum material

The present invention relates to a surface treatment method of a high strength aluminum material, and more particularly, to a surface of a high strength aluminum material including a micro peening process, a mechanical surface lapping, an anodizing process, and a digital color printing process. It relates to a processing method.

Conventional manufacturing process of wet color deposition of the dye on the porous film formed by the conventional method of color-colored surface treatment of aluminum material, in particular, anodizing (anodizing) process or coloration of the aluminum surface by electrolytic coloring is performed. Due to many process variables such as pH, temperature, mechanical agitation, immersion time, current density, etc., there were limitations of uniform and various color processing. In addition, the conventional manufacturing process requires a lot of labor and treatment facilities for treating environmental hazards and dye waste and effluent. As a result, the conventional manufacturing process had important improvement factors for market competitiveness such as product quality and production cost.

The electrolyte composition used in the conventional anodizing process is mainly based on a solution such as sulfuric acid, hydroxyl or chromic acid, but when the film is formed, a sudden temperature rise occurs due to joule heat, thereby dissolving the oxide film It is accompanied by action. Due to this dissolving action, it is difficult to form a dense oxide film, and there is a problem that the mechanical properties are very weak due to the formation of a porous film having a low density of the film itself.

The color of the film is changed according to the type of Al alloy, electrolyte and electrolytic conditions, and the anodic oxidation adaptability of Al material (Al alloy) is also different in corrosion resistance, dyeability and glossiness depending on the application. There is a difficulty. In addition, the oxide layer colored by anodizing the aluminum or aluminum alloy was discolored and discolored when exposed to sunlight over a long period of time, and it was difficult to obtain a uniform color with difficult working conditions. In addition, the conventional wet color coloring method of the aluminum material has a number of problems in which the color development is uneven, the surface hardness is low, and the surface of the high gloss is extremely limited to cope with high quality reliability.

The first technical problem to be solved by the present invention is to provide a surface treatment method of a high-strength aluminum material, including a micro peening process, mechanical surface lapping, anodizing treatment process and digital color printing process.

The second technical problem to be solved by the present invention is a new micro pinning capable of producing high quality products having excellent product reliability such as corrosion resistance and weather resistance while expressing images of various colors beyond the limitations of natural metal texture and color. The present invention provides a surface treatment method of a high strength aluminum material including a peening process, a mechanical surface lapping, an anodizing process, and a digital color printing process.

In order to achieve the technical problem to be achieved by the present invention, anodizing an aluminum alloy material that has undergone a micro peening process and a mechanical surface lapping process, to produce a porous film layer; Injecting ink into the porous coating layer of the anodized aluminum alloy material through inkjet printing to color the surface of the aluminum alloy material; And sealing the porous coating layer of the aluminum alloy material injected with the ink, thereby providing a surface treatment method of a high-strength aluminum material, including anodizing and digital color printing. .

And polishing the sealed aluminum alloy material.

The anodic oxidation treatment is preferably carried out in a sulfuric acid solution, in the temperature range of 0 ℃ to 25 ℃, 1A / dm 2 to 5A / dm 2 current density range and 15V to 50V electrolytic bath voltage range.

It is preferable that the sealing treatment is treated with pure purified water within a range of 90 ° C to 100 ° C for 2 to 25 minutes.

The aluminum alloy material may have a curved portion or a bent portion, and the inkjet printing may be capable of printing the curved portion or the bent portion.

It is preferable that the said polishing process contains any one or more of a high gloss process and a scratch-resistant process.

It is preferable to further include a; performing a printing for clear coating on the polished aluminum alloy material.

By applying the electronic printing technology using an inkjet printer, it is possible to produce a high-quality product with excellent product reliability while expressing a variety of colors and images with natural metallic texture and color.

By providing a dry color pigmented surface treatment method of the aluminum alloy material can meet the needs of consumers gradually diversified and individualized, there is an advantage to improve the competitiveness of the product by establishing a production system capable of producing small quantities of various types.

According to the present invention, since the dye is directly inkjet printed on the film formed through the anodizing process of the aluminum material, the coating liquid of the primer layer, which is the undercoat layer, is not applied. Therefore, it is possible to mass produce high quality products of uniform color and thickness at low manufacturing cost.

Hereinafter, it demonstrates in detail, referring drawings. 1 is an embodiment of a flow chart related to the electronic printing method of the reinforced aluminum material of the present invention. An electronic printing method of a reinforced aluminum material subject of the present invention comprises the steps of: anodizing an aluminum alloy material subjected to a polishing planarization process to generate a porous coating layer; Injecting ink into the porous coating layer of the anodized aluminum alloy material through inkjet printing to color the surface of the aluminum alloy material; And sealing the porous coating layer of the aluminum alloy material injected with the ink.

The high strength aluminum material is molded through a metal forming process such as press molding. Surface treatment of the formed high strength aluminum material, after forming the oxide film to enable surface protection and color processing by dye, and then inkjet printing the design of the graphic design, etc. at the exact position and interval on the surface Digital printing is performed by using, and sealing is performed by preventing pores of the anodized film on the surface of the digitally printed aluminum material to suppress corrosion and color development. At this time, the surface of the aluminum anodized film through a polishing process that satisfies high reliability, such as high gloss, scratch resistance, prevention of color development, or a printing process for cree coating to suppress stains and fingerprints, etc. It may further include.

It will be described in more detail below. In the present invention, the selection of the Al material is the most important and it is preferable that the aluminum or aluminum alloy material has no problem in molding and is excellent in anodization, coloring, corrosion resistance, and the like. After forming and processing the aluminum alloy material suitable for the above characteristics, after the micro-peening process to improve the characteristics of high surface strength and yield strength after molding, it removes the rolling marks, small scratches, etc. on the surface of the material It is processed by surface lapping process. Then inspect and racking.

2 is a schematic diagram comparing the conventional polishing (Fig. A) and the mechanical surface polishing (Fig. B). The surface as shown in Figure A of FIG. 2 is a case where the polish is applied to the surface of the material and polished. However, since the initial brightness is excellent, the light is diffusely reflected due to the lack of curvature of the surface. Later, the original hidden scratches or discs are exposed as the result of evaporation and dropping of the polish, which is not suitable for products requiring long term gloss. Fig. 2 of the present invention, Figure B is a case where the surface is first polished by lapping the surface to remove scratches or mango marks, such as tangerine peel, and then polished with a polishing agent so that the light appears clear and deep. The gloss of this method can maintain a relatively clear gloss for a long time because the surface remains a permanent plane even if the polish is removed over time.

Subsequently, degreasing and oxide film removal are performed on the aluminum alloy material. The degreasing process is performed with 10 to 20 parts by weight of neutral degreasing agent (AL ?? CLEAN ?? PASTE Brilim), 10 to 20 parts by weight of sulfuric acid, and 70 to 80 parts by weight of water at 60 ° C. to 70 ° C. for 30 seconds to 3 minutes. . The oxide film removing process is carried out for 20 seconds to 2 minutes at 15 ℃ to 25 ℃ with 7% NaOH oxide film removal liquid.

After the oxide film removing process is performed, a neutralization treatment is performed. The neutralization treatment is performed by immersing the aluminum alloy material for 20 seconds to 180 seconds at a temperature of 20 ℃ to 35 ℃ with 5 to 10% nitric acid solution.

Next, anodizing treatment is performed with an anodizing electrolyte. The anodic oxidation treatment is carried out at a current density of 1 m 2 to 5 A / dm 2 and a temperature of 15 V to 50 V at a temperature of 0 ° C. to 25 ° C. at an aluminum concentration of 0 to 20 g / L in a sulfuric acid solution of 20 to 30% (w / v). Carry out under electrolytic bath voltage. It is preferable to adjust the said voltage according to alloy type, temperature, area, etc. of a raw material. Such anodization and hard anodization are basically different in thickness and hardness, but about 300 million pores are formed in 1 mm2 in a hard anodic oxidation treatment of general low voltage.

In such anodization treatment, it is important to control various process parameters. In particular, the concentration of sulfuric acid, dissolved aluminum, the temperature of the electrolyte, the current density and the electrolysis time become important. Hereinafter, one by one will be described in detail.

As the sulfuric acid concentration changes, the electrolytic voltage during electrolysis changes, and this electrolytic voltage change affects the film performance. This is because if the sulfuric acid concentration is high, the dissolving action of the film becomes large, and the barrier layer on the surface of the film and the lower part of the fine pores becomes thin. 5 ?? 18V is applied in general anodization, but a voltage of 15 ?? 50V is required in high hardness anodization.

When aluminum is electrolyzed in the sulfuric acid electrolyte, Al ³⁺ melted from the aluminum is present in the electrolyte as dissolved aluminum in addition to the amount contributing to the formation of the film, and the concentration of the electrolyte is reduced by reacting with sulfuric acid to form aluminum sulfate. . For this reason, an increase in the amount of dissolved aluminum increases the resistance of the electrolyte, and a decrease in current density occurs at constant voltage electrolysis. For this reason, conventional electrolyte solution management should control the concentration of free sulfuric acid that does not bind with aluminum ions.

The temperature of the electrolyte greatly influences the current density. Increasing the current density also increases the electrolytic voltage, which increases the generation of Joule heat due to current consumption, and also adds heat of oxidation reaction, thereby increasing the temperature of the electrolyte. As the electrolyte rises, the chemical dissolving power of the electrolyte becomes stronger, so that the resulting film is dissolved and the film performance is reduced. As a countermeasure against this, a stirring device is required to remove the heat generated from the cooling surface and the aluminum surface during electrolysis. In general, when the current density has a corrosion resistance of the film produced at 100 ~ 200A / ㎡, it is preferable to control at 10 ℃ when the temperature of the electrolyte solution has a wear resistance of 20 ℃.

The relationship between the current density and the electrolysis time is an important item in determining the film thickness which affects and determines the film formation rate. Film thickness is calculated by the following equation.

Film thickness (µm) = K ⅹ Current density (A / m 2) 해 Electrolysis time / 100 where K is the coefficient, and several studies have been made with the film component and are now in the range of 0.264 to 0.364 values.

However, this calculation does not hold when the electrolysis time is long. This is because there is no balance between the rate of formation of the film and the rate of dissolution. In particular, Al ?? Cu ?? Mg (2000 series) alloys and AL ?? Zn ?? Mg (7000 series) alloys have a stronger tendency. According to a research report by Keller et al., The anodized film is divided into a barrier layer and a porous layer. Initially, the structure is dense, so that a barrier layer having a high hardness is formed and the structure is not dense. A porous layer is formed.

After anodizing film is formed on aluminum alloy material, color printing or design image through computer graphic is performed by inkjet printer at the exact position and interval on the surface. Digital printing is performed through an inkjet printer, and because digital printing, uniform and various colors and design images can be obtained.

When digital printing is performed on the porous aluminum alloy material, ink is injected into a minute space formed on the surface of the aluminum alloy. 3 shows an example of the cross-sectional change of the aluminum alloy material when the anodic oxidation process is performed. When printing is performed with a digital ink on a porous cell formed through anodizing, dye is introduced into the cell. The porous coating layer of the aluminum alloy material into which the dye is added is sealed (sealing treatment). Sealing treatment is carried out for 20 to 30 minutes at a temperature of 95 ℃ to 100 ℃ with 100% ultrapure purified water.

Subsequently, the colored and sealed aluminum alloy material is treated with a polishing process that satisfies high reliability such as high gloss, scratch resistance, and prevention of color development. Subsequently, a printing process for cree coating to suppress stains or fingerprints or the like is performed according to the application purpose. The drying process is then carried out, followed by appearance inspection and product evaluation. It is preferable to dry 5 minutes or more with a hot air dryer at 80 degreeC or more. Appearance inspection visually checks the coloration state, color uniformity, etc., and product evaluation evaluates color uniformity, hardness, thickness and corrosion resistance.

Next, the present invention will be described in more detail.

First, after confirming the Al plate specification, the rack was cut by a known method, cutting → baking processing → cutting processing → Micro Peening / polishing processing → appearance inspection.

The degreasing process was performed for 2 minutes at 65 ° C. in a 15% sulfuric acid solution with 15% neutral degreasing agent (AL ?? CLEAN ?? PASTE Purim). The oxide film removal is carried out for 30 seconds in a 7% NaOH oxide film removal liquid at 20 ℃. The neutralization treatment was performed by immersing the aluminum alloy material for 60 seconds in a 10% nitric acid neutralization treatment solution at 27 ℃.

The anodic oxidation treatment was performed with 16% sulfuric acid anodic oxidation solution for 30 minutes at an AL concentration of 4 g / L and an oxidation treatment solution temperature of 20 ° C. under 1.2 A / dm 2 current density and 16 V voltage conditions.

Coloring and images were printed using an inkjet printer as a dry color coloring surface treatment method of aluminum material. Examples of printed results are in FIG. 4. Sealing treatment was performed for 25 minutes at a temperature of 98 ℃ with 100% ultrapure water.

Subsequently, the color-colored anodized film was polished to satisfy high reliability such as high gloss, scratch resistance, and prevention of color development, and a clear coating was performed to suppress stains and fingerprints, etc. according to the application purpose.

As a result of the treatment as in the present example, a colored aluminum alloy product having a thickness of about 20 mu and a pencil scratch hardness of about 6 H was obtained. The aluminum alloy product of the present example was superior to brass and stainless steel in terms of hardness, color, surface treatment, processing cost and material cost.

The present invention can be utilized for various surface treatments of aluminum and aluminum alloy materials, and can be used in the aluminum material industry.

1 is an embodiment of a flow chart related to the surface treatment method of a high strength aluminum material of the present invention.

Figure 2 is a schematic diagram of the principle that high gloss when the lapping and polishing of the present invention is simultaneously processed.

Figure 3 is a schematic diagram showing that the ink is injected and sealed (sealed) by the digital printing in the porous cell of the present invention.

Figure 4 is an exemplary implementation example when the present invention is implemented in a mobile phone case.

Claims (7)

Anodizing an aluminum alloy material subjected to a micro peening process and a mechanical surface lapping process to produce a porous film layer; Injecting ink into the porous coating layer of the anodized aluminum alloy material through inkjet printing to color the surface of the aluminum alloy material; And Sealing the porous coating layer of the aluminum alloy material injected with the ink; surface treatment method of a high-strength aluminum material comprising a. The method of claim 1, Polishing the sealed aluminum alloy material; the surface treatment method of a high strength aluminum material further comprising. The method of claim 1, The anodic oxidation treatment is performed in a sulfuric acid solution, the high-strength aluminum material, characterized in that carried out in the temperature range of 0 ℃ to 25 ℃, 1A / dm 2 to 5A / dm 2 current density range and 15V to 50V electrolytic bath voltage range Surface treatment method. The method of claim 1, The sealing treatment is a surface treatment method of a high-strength aluminum material, characterized in that the treatment for 2 to 25 minutes in pure purified water within 90 ℃ to 100 ℃ range. The method of claim 1, The aluminum alloy material has a curved portion or a bent portion, and the inkjet printing is capable of printing the curved portion or the bent portion. The method of claim 1, The polishing treatment is a surface treatment method of a high-strength aluminum material, characterized in that it comprises any one or more of high gloss treatment and scratch resistance. The method of claim 1, And further performing printing for clear coating on the polished aluminum alloy material.

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