KR100629449B1 - Aluminium material of chemical coating method that use cr-free - Google Patents

Abstract

The present invention relates to a coating method capable of imparting various colors by coating a chromium free agent containing no hexavalent chromium on an aluminum material with a dye.

The present invention is a chromium pre-coating step (S40) for coating a chromium preagent on the surface of the aluminum material, and after the chromium pre-coating step (S40), the dye coloring step (S50) and the dye coloring step (S50) Coating with a step (S60) to stabilize the colored dye, and a drying step (S70) for drying after the stabilization step (S60), and another step is a dye coloring step (S40) to color the aluminum material, The dye is stabilized (S50), and characterized in that the coating by the drying step (S60) for drying after the stabilization step (S50).

The present invention has the effect of preventing environmental pollution by reducing the emission of harmful substances by using chromium-free chromium-free.

Cr free, stabilized, chemically treated, aluminum, organic dyes

Description

Aluminum material of chemical coating method that use Cr-free}

1 is an overall block diagram showing when a chromium pre-coating process and a dye coloring process are separated in a chemical conversion treatment method of an aluminum material using a chromium-free agent according to the present invention.

Figure 2 is an overall block diagram showing a process when the chromium preagent and the dye is added simultaneously in the chemical conversion treatment method of the aluminum material using the chromium preagent according to the present invention.

The present invention relates to a coating method capable of imparting various colors by coating a chromium free agent containing no hexavalent chromium on an aluminum material with a dye.

Surface treatments of aluminum materials include anodizing, chemical coating, electroplating, electroless plating, and vacuum plating. Representative surface treatment of the double aluminum is anodizing and chromate treatment, the anodizing treatment is a post treatment method of the aluminum or aluminum alloy anodized film of Korean Patent Application No. 10-1998-018460 (1998. 05. 22) The aluminum or aluminum alloy anodized film is immersed for 5 minutes to 30 minutes in an aqueous solution containing 1 ml / l to 100 ml / l of a water-soluble fluorine-based surfactant and having a temperature of 60 ° C. or higher, and the aluminum or aluminum alloy anodized film Silver surface is electrochromic, electrolytically colored or colored with an organic or inorganic substance, and 3.5 g of a temperature of 20 ° C. to 40 ° C. containing an aluminum or aluminum alloy anodized film containing 1 ml / l to 100 ml / l of a fluorine-based surfactant. / l to 5g / l nickel fluoride sealing solution soaked for 5 to 30 minutes to post-treat the aluminum alloy with an oxide film, and In the "coloration method of aluminum anodization film" of Korean Patent Application No. 10-1985-0006006 (August 20, 1985), which is another well-known technique, the coloring method is anodization of an aluminum-based metal having a film thickness of 12 mu or less. The coating is made of various metal salts of various metals such as iron, nickel, cobalt, chromium, stone, copper, silver, zinc, vanadium, titanium, cadmium, manganese, aluminum, and magnesium, and inorganic acids such as sulfuric acid, linic acid, acetic acid, citric acid, succinic acid, The two prior arts are generally treated with an activating bath containing an acid such as gloconic aside, glycine, ethylenediaminetetraacetic acid (including partial neutralized salts thereof), maronic aceic acid, and acid. Anodizing an aluminum material using a widespread anodizing technique is different from chemical conversion treatment using the chromate agent of the present invention.

In addition, the conventional coating method for chemically treating aluminum is to use a chromium hexavalent chromate agent, a degreasing step to remove the grease on the aluminum surface so that the film is formed well, and an etching step of grinding the surface using a solution to increase the surface area And a smut removal process for removing black smut on the aluminum surface, a chromate coating process using hexavalent chromium, and a hexavalent chromium content when hexavalent chromium is used as a drying process. Although it was possible to produce white and yellow color based on the thickness, since the hexavalent chromium chromate is a toxic substance, the chromate containing hexavalent chromium cannot be used due to the recent regulation of harmful substances, Other chromate agents used are harmless to humans but cannot express various colors. This problem was caused.

In order to solve the problems described above, in the present invention, by using a colorless chromium-free agent that does not contain chromium, it is possible to prevent the chromium-containing chromate agent from being converted into hexavalent chromate agent by aging and various color representations It is an object of the present invention to provide an aluminum material coating process that can be stably settled on a material without decoloring phenomenon, corrosion resistance, and adhesion even at high temperatures.

In the present invention for achieving the object, the degreasing step (S10) to remove the grease on the aluminum surface to form a film well, the etching step (S20) to increase the surface area by grinding the surface using a solution, and black lumps on the aluminum surface In the aluminum coating process by the smut removal step (S30) for removing the smut;

Chrome pre-coating step (S40) for coating the surface of the chromium free agent (S40), the dye coloring step (S50) for coloring the dye after the chrome pre-coating step (S40), and after the dye coloring step (S50) The dye is stabilized (S60), and characterized in that the coating by the drying step (S70) for drying after the stabilization step (S60).

Another process is characterized in that it is coated with a dye coloring process (S40) to color the aluminum material, a process to stabilize the dye (S50), and a drying process (S60) for drying after the stabilization process (S50). do.

Here, the step of stabilizing the dye (S50) is characterized by stabilizing the colored dye by mixing the zirconium compound, titanium compound, fluorine compound.

In addition, the chromium-free does not contain chromium, and the dye is an organic dye, characterized in that to prevent discoloration by heat by injecting a pre-heat treatment for 30 minutes in the temperature range of 180 ~ 200 ℃ in powder form before the solution preparation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall block diagram showing when the chromium pre-coating process and the dye coloring process in the chemical conversion treatment method of the aluminum material using the chromium preagent according to the present invention, Figure 2 is an aluminum using a chromium preagent according to the present invention In the chemical conversion coating method of the material, the entire block diagram showing the process when the chromium preagent and the dye are added simultaneously.

In general, chromate treatment is a chemical or electrochemical treatment of aluminum, cadmium, copper, magnesium, silver, zinc and their alloys to form compounds of hexavalent chromium and other compounds in a solution mainly containing chromic acid or dichromate. The rust preventive film is formed by immersing the article.The electrolytic oxide film is a strong nonconductor, but the chemical conversion film is a good conductor of electricity and has low abrasion resistance, while the corrosion resistance is very good, the appearance is beautiful, and fingerprints, etc. It does not burn, it can be dyed, and the coating layer forms an inert oxide layer, self-healing in the worn part of the coating, film formation without flaking, and chemical treatment method is selected, so it is easy to process even complex structures. Production is also possible.

1 is a method of separately coating a chromium pre-coating process and a dye coloring process in a chemical conversion treatment method of an aluminum material using a chromium preagent.

First, the degreasing step (S10) is to remove the lubricating oil and mineral oil, etc. buried on the aluminum surface so that the film is formed well so as not to affect the plating.

The etching step (S20) is to widen the surface area by grinding the surface using a solution, and generally divides the wet etching and the dry etching, the wet etching corresponds to the corrosion, and the dry etching is used to sand the surface using a sandblasting or the like. In the process, caustic soda is used as the solution to be added.

The smut removal process (S30) is to remove smut, which is an impurity of a dissimilar metal, which does not fall with the oxide remaining in the etching process (S20) on the surface of aluminum and removes smut (Smut) on the surface of aluminum. In order to do this, alkaline washing and pickling are generally used. In particular, sulfuric acid or phosphoric acid may be used for pickling, but when the temperature is low, the reaction may not be performed well.

The chromium pre-coating process (S40) is to form a plurality of pores on the surface of the aluminum material, and the chromaticity treatment to coat the surface of the aluminum material with a colorless chromium free agent (pH) is 4.5 ~ 5.5 and does not contain chromium.

The dye coloring step (S50) is a step of coloring a dye after the chromium pre-coating step (S40), and a step of coloring a dye to realize various colors after the chromium pre-coating step (S40), wherein the dye is an organic dye recorder. Lecotan Gold P-C ₃₂ H ₂₁ N ₇ O ₁₄ S3, Lecotan Orange FO and Lecotan Yellow GC- C ₁₆ H ₁₄ N4O8S, Lecotan It is a water-soluble azo acid dye such as Yellow M (Lecotan Yellow MC ₁₈ H ₁₅ N ₃ O ₃ S), each color is added to express the color to express the color and the chromium pre-coating without heat treatment of the dye If the color is immediately added after the step (S40), the color of the dye may be discolored, and the dye is heat-treated for about 30 minutes at a temperature range of 180 to 200 ° C. to prevent discoloration due to heat. Is the dye is used that the PH (acidity) of 4.5 to 5.5.

The stabilization process (S60) is a process of stabilizing colored dyes after the dye coloring process (S50), forming pupils on the surface of an aluminum material and coloring using chromium-free and dyes, followed by zirconium compounds, titanium compounds, and fluorine compounds. It is a step of stabilizing by protecting the colored dye on the aluminum material in a ring form so that the colored dye can stick to the surface of the aluminum material by mixing evenly mixed in the colored aluminum material.

The following examples show stabilization test conditions and composition examples through chromium-free.

(Example 1)

Cr-free stabilization test conditions and composition examples

Condition Working conditions and composition result One 1-1 Hardener 5 ml / l Stabilizer 5 ml / l PH 10. Temperature 60 ℃ time 1-2 Temperature flush 60 ℃ Time 5 seconds Smear occurs. Has a surface slime coating. No discoloration phenomenon. Slime (surface stickiness) 2 3-1 Do not use hardener. Stabilizer 3 ml / l P H 10 Temperature 40 ℃ time 20 sec 2-2. The viscous coating properties are somewhat improved but not satisfactory. No discoloration phenomenon. 3 3-1 Stabilizer 10 ml / l P H 7 Temperature 27 ~ 38 ℃ time 20 seconds 3-2 Warm water Distilled water Temperature 60 ℃ Time 5 seconds Increased adhesiveness and satisfies the sealing condition of the film surface (No mucus phenomenon) Corrosion resistance is improved than the treated object (over 168 hours) Temperature effect: Drying phenomenon may occur due to the movement time to the warm water after stabilization treatment. It is desirable to avoid the high temperature working temperature conditions.

If the concentration of stabilizer is too low under the test conditions, white flow may occur on the surface and the iridescent color may affect the appearance, so the control range should be maintained at 5 to 10 ml / l.

The water hardener is affected by water contamination, that is, purity (iron, phosphate, sulfate), and the water used during the experiment is hardly affected by the water hardener during the initial bath, so it is not necessary to put it in the distilled water bath.

As a result of the test, the solution may be contaminated by the influx of washing water or working environment conditions after the coloring operation, which is the source of contamination by repetitive work, and the use of hardener may be suitable at about 10 ml / l per 100 PPM of water pollution.

If the degree of contamination is visible to the naked eye, the solution will change from the transparent color at the first time of bathing to the turbid color depending on the frequency of operation.When water is added, the solution will be milky. It was the best.

The drying step (S70) is to dry the aluminum material passed through the dye coloring step (S60) 50 ~ 150 ℃ to completely remove the moisture on the surface of the aluminum material.

Figure 2 is a process when the chromium-free agent and the dye is added at the same time in the chemical conversion coating method of the aluminum material using the chromium-free agent, the degreasing step (S10) to remove the grease on the aluminum surface to form a film well, and the surface using a solution It is carried out by an etching process (S20) to increase the surface area by grinding and a smudge removal process (S30) to remove smut, which is a black mass on the aluminum surface, which is separated from the chromium pre-coating process and the dye coloring process. The same as the process and will be described below the other coating process.

The dye coloring process (S40) is a process of coloring by adding a chromium free and a dye having an acidity (PH) of 4.5 to 5.5 at the same time to color the aluminum material, when the treatment using a trivalent chromate agent passes over time While the trivalent chromate is aging and is reduced to the hexavalent chromate, the reduction to the hexavalent chromate is prevented by using chromium-free chromium to prevent reduction of the hexavalent chromate with harmful ingredients. It is intended to be able to be colored simultaneously with the described organic dyes.

The stabilization step (S50) is a method of separating and coating the chromate treatment process and the dye coloring process to form a pupil on the surface of the aluminum material and coloring using chromium-free and dye, and then zirconium compound, titanium compound, fluorine compound It is a step of stabilizing by protecting the colored dye on the aluminum material in a ring form so that the colored dye can stick to the surface of the aluminum material by mixing evenly mixed in the colored aluminum material.

In addition, the drying step (S60) is to dry the aluminum material passed through the dye coloring step (S50) 50 ~ 150 ℃ to completely remove the moisture on the surface of the aluminum material.

The comparative example below compares the hexavalent chromate and chromium-free in operation.

(Comparative Example 1)

-Coating weight comparison

The coating weights of hexavalent chromate and chromium-free are relatively comparable. The coating weight was measured by an ultrasonic rangefinder (Porta-spec) in the case of hexachromate, and chromium-free was peeled off to determine its weight. Hexavalent chromate may react continuously when aluminum is introduced into the liquid, resulting in a thicker thickness and poor adhesion. Chrome Free has its own limitations and adhesion does not deteriorate even at the heaviest coating weight.

<Table 1>

Table 1 shows the comparison values according to Comparative Example 1.

Hexavalent Chromate Chrome-free 0.01-1.29 g / M ² 0.27-0.75 g / M ²

(Comparative Example 2)

-Thickness comparison of coating film

When the coating thickness is compared with the coating weight, hexavalent chromate and chromium free show similar values. The immediately formed film shows a very different form, and the hexavalent chromium chromate needs to be cured for 24 hours to obtain a relatively hard film in a soft gel state, and chromium free has a hard amorphous crystal structure and does not need to be cured.

Hexavalent chromate generally has a yellow to brown color depending on the coating thickness and the amount of hexavalent chromium. When hexavalent chromium is removed by decolorizing the film, it becomes a transparent color.

<Table 2>

Table 2 shows the thickness comparison values of the coating film.

Hexavalent Chromate Chrome-free 38-3,800 A 50 to 300 A 0.0038 to 0.38 um 0.005 ~ 0.03 um

(Comparative Example 3)

-Effect on heat

When the hexavalent chromate substituted coating film is subjected to heat of 71 ° C. or higher, the coating film is dehydrated and cracks are generated, resulting in poor corrosion resistance and poor paint adhesion.

The chromium-free does not deteriorate corrosion resistance and paint adhesion even when heated to 350 ℃, and the film has no dehydration or cracks.

(Comparative Example 4)

-Electrical resistance

In the chromium-free working solution, the AL6061 specimens were treated with different chromium-free treatment times, and the conductivity of the coating was tested. Ten specimens of each specimen were measured to obtain a resistance of up to 5 milliohms.

As a result, the result of 3-minute deposition shows a relatively high resistance value and excellent corrosion resistance.

<Table 3>

Table 3 shows the results of the electrical resistance measurements.

168 hours saline spray footage per sample Average resistance before salt water test Average resistance after salt spray test 12 feet of one minute deposition 0.92millimhos 0.96millimhos 4 feet of 2 minutes deposition 0.80millimhos 0.81millimhos One minute three minutes deposition 0.80millimhos 0.86millimhos 4 minutes no pit 0.33millimhos 0.48millimhos There is no five minutes pit 0.19millimhos 0.35millimhos

(Comparative Example 5)

-Salt spray result (substituted coating film and coating film)

Hexavalent chromate and chromium-free were tested on commonly used alloys. The specimens were tested for the corrosion resistance of the coating coated with polyester powder as well as the substituted coating film. The failure was judged to be four or more feet in two of the three specimens, with a size of 2.4 in ² .

If the copper content is more than 2.0%, the corrosion resistance is poor when the chromium-free treatment is performed, and copper adversely affects the corrosion resistance of the chromate treated film, but not the same amount. Low copper content Chromium-free treatment results in more corrosion resistant alloys than hexavalent chromate.

<Table 4>

Table 4 shows the results of the salt spray measurement (initiation time hr).

Aluminum alloy Copper content% Chrome Free Salt Spray Results Hexavalent chromate salt spray results A356F 0.25 576 > 1080 A380F 4.0 <72 <72 1100 0.2 > 1128 432 2024 4.9 <24 168 3003-H14 0.2 > 1128 168 5052-H32 0.1 > 1128 > 1128 5086 0.1 816 > 1128 6022-t4 0.11 > 1128 > 1128 6061-T4-E29 0.11 > 1128 576 6061-T6 0.4 > 1000 648 6111-T4 0.9 > 1128 432 611-T4-E29 0.9 288 1080 7075-T6 2.0 <72 672

<Table 5>

-Test result table conducted by Korea Testing and Research Institute for salt spray.

Test Items Result Test Methods Neutral salt spray test (168h, white rust occurrence) clear KS D 9502: 2002 (Conditions for Assisting Clients)

(Comparative Example 6)

-Solution variables

In general, chromium-free can directly replace the chromate process without converting a specific process. The most important thing here is that the working temperature of chrome-free is room temperature.

<Table 6>

Table 6 compares the working variables of hexachromate and chromium-free.

Hexavalent Chromate Chrome-free density 15 g / liter 5% of volume PH 1.3 to 1.6 4.5 to 5 Temperature 16 ~ 35 ℃ 16 ~ 49 ℃ time 15 seconds to 3 minutes 3 to 10 minutes supplement PH control with nitric acid and sodium hydroxide PH adjustment with ammonia water Drying temperature 61 ℃ or less 60 ℃ or higher Film hardening 24 hours Cured immediately

When comparing chromium-free and hexavalent chromate as shown in Comparative Examples 1, 2, 3, 4, 5, 6 and Tables 1, 2, 3, 4, and 5, chromium-free forms a stable film and cures immediately. There is a limit to the amount of response. For most alloys with a copper content of 2% or less, it has excellent salt spray results and good adhesion between powder coating and solvent paint. In addition, heavy metals are not included and working acidity (PH) is 4.5 ~ 5.5, which is good workability.

<Table 7>

-Test result table of Korea Institute of Industrial Technology for toxic substance detection.

ingredient Pb (mg / kg) Cd (mg / kg) Hg (mg / kg) Cr (mg / kg) Detection Not detected Not detected Not detected Not detected
<Table 8>
Table 8 shows the color change test by temperature change, and the color change after the chromium-free treatment was visually compared with the standard specimen by applying thermal change to the dye whose pH was adjusted for 30 minutes in advance.
Leco tan gold P Lecotan Orange P Lecotan Yellow P Yellow M 60 ℃ × × × × 70 ℃ × × × × 80 ℃ × △ × × 90 ℃ × △ × △ 120 ℃ △ ○ × △ 140 ℃ ○ ○ △ ○ 180 ~ 200 ℃ ○ ○ ○ ○
(○: none. △: slightly present. ×: severe change)
As shown in Table 8, it can be seen that the dye which is subjected to the thermal change of the organic dye of the present invention at 180 ° C. to 200 ° C. for 30 minutes has no color change even after the coating drying temperature.

As described in detail above, the present invention can be used in various parts such as communication parts, precision mechanical parts that require conductivity, automobiles, aircraft parts, etc., can be realized in various colors, and can increase productivity with fast plating speed and low defect rate. By using chromium-free, which does not contain chromium, it reduces the emission of harmful substances and has a great effect on preventing environmental pollution.

Claims (5)

Degreasing process (S10) to remove grease on the aluminum surface to form a film well, etching process (S20) to increase the surface area by grinding the surface using a caustic soda solution, and to remove the smut, which is a black mass on the aluminum surface In the aluminum coating process by the smut removal step (S30); A chromium precoat process (S40) for coating a surface of an aluminum material with a chromium free agent having an acidity (PH) of 4.5 to 5.5 and a chromium free agent, and after the chromium precoat process (S40), to realize color in a powder state before preparing a solution. Hazard acidity (PH) is 4.5 to 5.5 and the dyeing process (S50) for coloring the organic dye pre-heat-treated for 30 minutes in the temperature range 180 ~ 200 ℃, and to stabilize the colored organic dye after the dye coloring process (S50) Coating method of aluminum material using a chromium pre-treatment, characterized in that the coating step (S60), and the drying step (S70) for drying after the stabilization step (S60). Degreasing process (S10) to remove grease on the aluminum surface to form a film well, etching process (S20) to increase the surface area by grinding the surface using a caustic soda solution, and to remove the smut, which is a black mass on the aluminum surface In the aluminum coating process by the smut removal step (S30); The acidity (PH) is 4.5 ~ 5.5 for the color in the state of powder before preparing the solution in the aluminum material, and the organic dye and acidity (PH) are 4.5 ~ 5.5 and pre-heated for 30 minutes in the temperature range of 180 ~ 200 ℃, and do not contain chromium. A dye coloring step (S40) for simultaneously adding and coloring chromium free agent, a step (S50) for stabilizing the colored organic dye after the dye coloring step (S40), and a drying step for drying after the stabilizing step (S50) Chemical conversion coating method of the aluminum material using the chrome free agent, characterized in that the coating (S60). The method according to claim 1 or 2, Process for stabilizing the dye (S50, S60) is an aluminum material chemical conversion coating method using a chromium free agent, characterized in that to stabilize the colored dye by mixing the zirconium compound, titanium compound, fluorine compound. delete delete

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