JP2684472B2 - Surface-treated aluminum material and its treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a surface-treated aluminum or aluminum alloy material used for building materials, fin materials for heat exchangers, printed wiring boards, can tab materials, and the like, and surface treatment thereof.

[0002]

2. Description of the Related Art A number of techniques have been proposed so far as surface treatment methods for aluminum or aluminum alloys for the purpose of corrosion resistance, prevention of discoloration, improvement of coating film adhesion, and beauty of appearance.

For example, among the main ones which are relatively effective among them, JP-A-50-86540: Aluminum substrate is pretreated with an aqueous solution of alkali silicate and then treated with vinylidene chloride resin to form an anticorrosion film. . JP-A-64-34731: The surface of an aluminum plate is pretreated with weak alkaline degreasing and then treated in an aqueous solution containing an oxidizing agent to form a boehmite film. JP-A-59-133382: An alkaline aqueous solution containing a chelating agent of about 3 to 6 g / l is spray-washed. JP-A 1-212775: p containing chloride ion
PH 13 after etching in an acidic aqueous solution of H2 or less
The above-mentioned base treatment for etching in an alkaline aqueous solution. JP-A-2-97700: After degreasing pretreatment in a surfactant-added aqueous solution, anode polarization electrolytic treatment and cathode polarization electrolytic treatment are alternately performed. However, each has its own problems.

The method (3) has a problem in that treatment unevenness is likely to occur during the alkali silicate treatment and it is difficult to obtain a uniform film. In the above method, problems such as film defects and blackening at the time of subsequent boehmite treatment, coating treatment, etc. may be unsolved, probably due to weak alkaline degreasing treatment.

In the method (1), the blackening of the material surface cannot be completely avoided because the ability to remove the oxide film by the chelating agent alone is insufficient. Although the method (1) is a method capable of completely removing the oxide film, it is a two-step process, resulting in poor productivity and an increase in cost. In addition, since smut is generated during the process, if it is not completely removed, problems such as coating film defects will occur in subsequent coating and chemical conversion treatments. In this method, pretreatment for degreasing with a surfactant tends to be insufficient, which causes unevenness during electrolytic treatment.
In this case, a large amount of electric power is required to obtain a uniform processing surface, which leads to an increase in cost. Further, it has a problem that it cannot be applied to an object having a complicated shape, which indicates the difficulty of the surface treatment.

[0006]

The cause of defects such as poor corrosion resistance, discoloration, and poor adhesion of coating film of aluminum material after surface treatment is generated on the aluminum surface during the manufacturing process such as casting, rolling and molding. The surface oxide film is involved. Although this surface oxide film is thin, it is a porous layer containing rolling oil, etc., and has many cracks, resulting in poor wettability to paints, poor adhesion, and poor corrosion resistance. .

Further, if the surface treatment is carried out while the surface oxide film is not sufficiently removed, the oxide film component is incorporated into the hydration oxidation treatment (boehmite treatment) film or the anodization treatment film to form a black or brown film and the appearance. Cause damage. In addition, in anodizing treatment and chemical conversion coating treatment (chromate, etc.), the start of the coating formation reaction is affected by the dissolution of the aluminum surface, so if a non-uniform oxide coating is attached, uneven reaction will occur and coating defects will occur. Occur.

Therefore, in order to obtain a highly corrosion-resistant aluminum material having a beautiful appearance, it is necessary to completely remove the oxide film formed during casting, rolling and molding in advance.

The degree of removal of this oxide film is measured by EPM.
It is possible to measure by spectroscopic measurement such as A, ESCA, etc., by means such as SEM, TEM, etc., but it is troublesome and it is difficult to measure the amount of residual oxide film nondestructively except for small instruments. So far, the pretreatment conditions are often determined based on experience and intuition, and as a result, the deoxidation film treatment is performed in excess of the required amount, or conversely, chemical conversion treatment without performing a sufficient amount of deoxidation film treatment. Often caused problems.

Therefore, an index that can be easily measured and that is accurate is required. However, it is not always important to measure the residual oxide film amount itself. The point is that a simple physical quantity that reflects the amount of residual oxide film is enough.

Based on this concept, the present invention provides an aluminum material that efficiently removes an oxide film while simply determining the amount of the residual oxide film and does not affect the subsequent surface treatment, a surface treatment method therefor, and a surface treatment. When applied, it provides an aluminum material having high corrosion resistance and a beautiful appearance as a whole.

[0012]

In the present invention, the color tone (S) after surface treatment with an aqueous solution containing a chelating agent and amines is S = (X ² + (3.388Z-3Y) ² ). ^The present invention provides an aluminum material characterized in that ^1/2 ≧ 70 (XYZ is tristimulus value of color), and the aluminum material comprises an aluminum material, a chelating agent of 0.005 mol / l or more, an organic amine. 5g / l or more, phosphate concentration 100ppm or less,
Surface treatment is performed with an aqueous solution having a sulfate radical concentration of 500 ppm or less, and the color tone (S) becomes S = (X ² + (3.388Z-3Y) ² ) ^1/2 ≧ 70 (XYZ is the tristimulus value of color) The present invention provides a surface treatment method for an aluminum material, which further comprises treating the aluminum material with a chelating agent of 0.005 mol / l or more and an organic amine of 5 g / l or more, and a phosphate concentration of 100 ppm.
Hereinafter, surface treatment is performed with an aqueous solution having a sulfate radical concentration of 500 ppm or less, and the color tone (S) is S = (X ² + (3.388Z-3Y) ² ) ^1/2 ≧ 70 (XYZ is a tristimulus value of color) The present invention provides a surface treatment method for an aluminum material, which is characterized by performing another surface treatment after the above treatment.

In the present invention, the chelating agent is EDTA.
(Ethylenediaminetetraacetic acid), CyDTA (trans-
1,2-cyclohexanediamine-N, N, N ', N'
-Tetraacetic acid), GEDTA (glycol ether diamine tetraacetic acid), DTPA (diethylenetriamine-N, N,
N ', N ", N" -pentaacetic acid), TTHA (triethylenetetramine-N, N, N', N ", N"', N "'-hexaacetic acid), NTA (nitrilotriacetic acid), HEDTA ( N-
(2-hydroxyethyl) ethylenediamine-N,
N ', N "-triacetic acid), DCTA (trans-1,3-)
Diaminocyclohexanetetraacetic acid), TPHA (tetraethylenepentamineheptaacetic acid), EDTP (ethylenediaminetetrapropionic acid), and other polyvalent sequestering agents that are aminopolycarboxylic acids. This is preferably the free aminopolycarboxylic acid or its alkali metal salts, such as the Na salt. The concentration in the aqueous solution is 0.005mo
l / l or more is required. If it is less than 0.005 mol / l, the effect as a chelating agent is insufficient and the etching action is weak, resulting in the trouble that a part of the oxide film remains, the color tone cannot achieve S ≧ 70, and the chelating agent is consumed. As a result, the deterioration of the liquid becomes severe and the operation becomes unstable, which causes problems such as blackening, poor adhesion and poor corrosion resistance after the surface treatment. Further, there is a problem that smut is likely to occur on the surface of the aluminum material and a desmutting process is required.

As organic amines, ethylenediamine, triethanolamine (TE
A), diethanolamine and the like are preferable. 5 as usage
A concentration of g / l or higher is preferable. When the concentration is low such as less than 5 g / l, there is no synergistic effect with the chelating agent, the oxide film remains even after the treatment, the color tone S ≧ 70 cannot be achieved, and there are problems of blackening, poor adhesion and poor corrosion resistance. Inevitable.

The surface treatment solution must have a sulfate radical concentration of 100 ppm or less and a phosphate radical concentration of 500 ppm or less. If the amount of these ions exceeds the specified amount, the surface is blackened, and the color tone of S ≧ 70 cannot be achieved.

To remove these anions, it is preferable to use so-called pure water such as ion-exchanged water or distilled water, or use the one after removing by adding an adsorbent.

The pH of the surface treatment liquid is not particularly limited,
It is preferable that pH = 4 to 11 is easy to handle. In addition, alkaline substances (for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide), acidic substances (sulfuric acid,
Other than phosphoric acid, it may contain a mineral acid such as hydrochloric acid or a carboxylic acid such as citric acid). Further, a surfactant such as a nonionic surfactant may be included.

The oxide film is removed in a short time by treating the surface of the aluminum material with the surface treatment aqueous solution containing the above-mentioned chelating agent. In this case, since the smut does not adhere to the surface, the desmut treatment is unnecessary and the process is shortened. The treatment may be either dipping or spraying.

The treatment conditions are a temperature of 30 ° C. to a boiling point and are not particularly limited. It may be appropriately selected from the relationship between the amount of oxide film of the sample and the processing time. About 50 ° C to 90 ° C is preferable in terms of processing time and handling. The processing time is several seconds, about 30 minutes, preferably about 1 to 15 minutes. It may be appropriately determined from the aqueous solution concentration, temperature, pH, and the amount of oxide film.

To measure the color tone S, the sample being surface-treated is washed with water and dried, and then X, X is measured by a colorimeter such as a color meter.
It is only necessary to measure the Y and Z values, substitute them into the formula S = (X ² + (3.388Z-3Y) ² ) ^1/2 , and calculate the S value. Since the color measurement can be done in a few seconds, It has become possible to perform proper processing without relying on intuition as in the past, without performing excessive deoxidized film processing or insufficient deoxidized film processing.

The aluminum material from which the problematic surface oxide film has been removed in this way is subjected to hydration oxidation treatment, chromate treatment,
Anodizing treatment, AC electrolytic treatment in alkaline aqueous solution,
It is applied to processes such as coating with corrosion resistant paint.

As the hydration oxidation treatment, dipping or spraying treatment in deionized water or the like at 50 ° C. or higher is performed. JP-A-59-
It may include an oxidant as disclosed in 211578. It may also contain an amine compound such as triethanolamine as disclosed in JP-A-64-34731. The treatment time may be appropriately determined from the relationship with the treatment liquid temperature, the required film thickness, etc., but usually 1 to 6
It can be selected from the range of about 0 minutes. pH is 4-11
The degree is good, and if it is less than 4 or more than 11, the film formation is inadequate or not formed, which is unsuitable.

There are several chromate treatments. For example, in the coating type chromate treatment, a resin such as SiO ₂ , polyacrylic acid, Zr salt, Ti salt, etc. may be contained, but an aqueous solution containing Cr ⁶⁺ , Cr ³⁺ is used, and a roll coater, spray, brush coating, etc. The above method may be applied appropriately. The film thickness may be determined according to the purpose and is usually 0.
It may be selected from the range of about 1 to 5 g / m ² . In the case of a baking type, a baking process is performed as necessary.

British Patent 80 for chromate phosphate treatment
3405 (liquid temperature: 30 to 70 ° C.,
Bath composition: F ion = 100 to 5000 ppm, Cr ion = 0.01 to 2%, phosphate ion = about 0.1 to 7% may be appropriately selected. ) Etc. can be used. The amount of coating may be appropriately selected, but the amount of chromium is 10 to 100 mg / m
A range of ² is good.

As the chromic acid chromate treatment, Albond CRN method (UK patent 240623) (liquid temperature: 20-
30 ° C., treatment time: 2-3 minutes, bath composition: chromic acid = 9 g
/ L, sodium tungstate = 3.5 g / l, sodium fluoride = 4.5 g / l) and the like can be used.

As the anodizing treatment, electrolytic treatment is carried out in an aqueous solution of sulfuric acid, oxalic acid, phosphoric acid, boric acid or the like. The film thickness may be determined from the range of about 0.1 to 30 μm depending on the purpose.

In alternating current electrolysis in an alkaline solution, JP-A-63-258674 and JP-A-2-18290 are available.
AC electrolysis treatment can be performed in an alkaline solution as disclosed in US Pat.

Further, as a corrosion resistant paint coating, Japanese Patent Laid-Open No. 62-62
Although it is not necessary to specify it, since the acrylic resin as disclosed in -105629, the fluorine resin as disclosed in Japanese Patent Application No. 2-74578, etc. are generally coated with resin, the corrosion resistance is improved. Further, the corrosion resistance can be further improved by applying a resin as a paint and baking it as necessary.

[0029]

In the present invention, the method of measuring the color tone S by colorimetry does not directly measure the amount of oxide film, but the amount of oxide film is reflected and the lower limit of the S value should be set to an appropriate value. I found that it can be used as a control value in. Looking at the relationship between the amount of oxide film and the S value of color tone, S ≧ 70 when the surface oxide film is removed (see FIG. 1). It has been found that an aluminum material having good adhesion resistance, corrosion resistance, and discoloration resistance can be manufactured by performing a deoxidizing film treatment so as to obtain such a surface.

In this case, in order to efficiently remove the surface oxide film, the deoxidizing film treatment is performed with an aqueous solution containing a chelating agent, but the chelating agent forms a complex compound with many metals and stabilizes it. The generation of smut on the surface can be prevented and the etching power can be maintained high, so that the oxide film can be removed in a short time. In addition, the eluted material components are difficult to scale because they are treated with a chelating agent, and management of bathtubs, pipes, etc. is easy.

It was found that the combined use of organic amines such as triethanolamine with the chelating agent enhances the deoxidizing film ability of the chelating agent. When the amount of amines added is less than 5 g / l, the deoxidized film ability is low and the treatment requires a long time.

Further, it has been found that when a sulfate group and / or a phosphate group is present in the treatment liquid, a black to yellow film is newly formed during the treatment, which is particularly remarkable in the case of Mg-based aluminum alloy. Therefore, it is necessary to suppress the amounts of these anions in the liquid to 500 ppm and 100 ppm or less, respectively.

Further, if the pH is adjusted by adding an alkali or an acid to the surface treatment aqueous solution, the processability is further improved by the reaction between the chelating agent and aluminum and the etching effect by the reaction with the alkali or acid. Further, by adding a surfactant, the oil content can be effectively removed and the wettability between the reagent and the material can be improved, so that the processability can be further improved.

[0034]

The present invention will be described in more detail with reference to the following examples. (Example 1) Under the conditions shown in Table 1, EDTA.2Na salt TEA, sulfate group, JIS A5182-H19 plate material,
Treated with a surface treatment solution containing phosphate radicals, washed with water,
After drying, the color was measured with a color computer SM-3 manufactured by Suga Test Instruments Co., Ltd., and the S value was calculated from the X, Y, and Z values. Further, this plate material was subjected to hydration oxidation treatment at 100 ° C. for 10 minutes in ion-exchanged water, dried, and similarly subjected to color measurement with a color computer SM-3, and S value was calculated from X, Y and Z values. Further, the plate material was subjected to an SST test (1000 hours) according to JIS Z2371-1988 to evaluate the corrosion resistance by the corroded area. Table 1 shows the results.

(Comparative Example 1) Using the same plate material as in Example 1,
Similar to Example 1, surface treatment was performed under the conditions shown in Table 1, color tone measurement was performed, hydration oxidation treatment was performed, and color tone measurement was performed.
Further, an SST test was conducted. Table 1 shows the results.

(Comparative Example 2) Using the same plate material as in Example 1,
First, a 10% aqueous solution of NaOH was used for alkali etching treatment at 40 ° C. for 5 minutes, and a solution of weak alkaline degreasing was performed using a sodium phosphate bath (70 ° C., 3 minutes). After these plate materials were washed with water and dried, the color tone was measured in the same manner as in Example 1. Then, in accordance with Example 1, hydration oxidation treatment, color tone measurement and SST test were performed. Table 1 shows the results
Shown in

[0037]

[Table 1]

According to this Example 1, if the color tone (S value) after the treatment by the method of the present invention is 70 or more, the color tone does not become dark even if the hydration oxidation treatment is carried out, and a white highly corrosion-resistant film is obtained. I was able to.

(Example 2, Comparative Example 3) JIS A518
The plate material of 2-H32 was treated with the treatment liquid and the treatment conditions shown in Table 2, washed with water, dried, and color-measured with the same color computer SM-3 as in Example 1, and the X value, the Y value, and the S value were converted to the S value. I asked. These plates were then tested in boiling water in boiling water (100
(10 ° C., treatment for 10 minutes), dried and again measured color, and visually measured change in color tone of appearance. For the visual judgment, one having no black discoloration was set to 1, and the one having the maximum black discoloration was set to 5, and a 5-grade evaluation was performed. Table 2 shows the results.

[0040]

[Table 2]

As a result, it has been found that when the S value is 70 or more, a good color tone can be maintained without blackening even if boiling water treatment is performed without any other surface treatment.

(Example 3, Comparative Example 4) JIS A120
The plate material of 0-H24 was treated with the treatment liquid and the treatment conditions shown in Table 3, washed with water, dried, and color-measured in the same manner as in Example 1,
The S value was obtained from the X, Y, and Z values. Next, a coating type chromate solution (manufactured by Nippon Paint Co., Ltd., NRC-300) was coated (coating film thickness: 1 μm), dried at 100 ° C., and then 1,
1,1-trichloroethane (Etana V, Asahi Kasei Corporation)
It was immersed in G) (74 ° C., 10 minutes). An aluminum fin cleaner (manufactured by Seiwa Kogyo Co., Ltd., aluminum fin cleaner W5 times diluted, pH 12 to 13)
The process of dipping for 10 minutes in 15 minutes and washing with running water for 15 minutes was set as one cycle, and after 10 cycles of treatment, a glutinous eye adhesion test (gouger's eye 1 mm interval) was performed. Further, some test pieces were subjected to SST (JIS 2371-1988 compliant, 2000 hours). The results are shown in Table 3.

[0043]

[Table 3]

It can be seen that when the color tone S value after pretreatment is 70 or more, the aluminum material is excellent in both adhesion and corrosion resistance.

(Example 4, Comparative Example 5) JIS A110
The plate material of 0-H18 was treated with the treatment liquid and the treatment conditions shown in Table 4, washed with water, dried, and color-measured in the same manner as in Example 1, and X,
The S value was calculated from the Y and Z values. Next, 15 wt.
% Sulfuric acid aqueous solution, anodizing electrolysis was carried out at 20 ° C. and 1.5 A / dm ² for 50 minutes, followed by washing with water and drying. This test piece is J
CASS test 2 according to IS H8681-1988
000 hours. Table 4 shows the results.

[0046]

[Table 4]

If the S value is 70 or more, a coating having few coating defects and good corrosion resistance can be treated in one step. A relatively good film can be obtained also in the caustic etching-desmut treatment, but it is a two-step treatment and is a method with low productivity.

(Example 5, Comparative Example 6) JIS A110
The plate material of 0-H24 was treated with the treatment liquid and the treatment conditions shown in Table 5, washed with water, dried, and color-measured in the same manner as in Example 1, and X,
The S value was calculated from the Y and Z values. Next, this test piece was subjected to an alternating current electrolytic treatment in a sodium phosphate electrolyte solution under the conditions of 8 A / dm ² and 30 seconds. Further, an epoxy resin for electrical insulation was applied to a copper foil having a thickness of 35 μm and dried, and this was laminated on the above-mentioned aluminum plate material, and heat-pressed for 90 minutes at 392 N / cm ² , 170 ° C. This laminated board was subjected to a solder heat resistance test in accordance with JIS C6481 and the time until peeling occurred was measured. Table 5 shows the results.

[0049]

[Table 5]

(Example 6, Comparative Example 7) JIS A300
The 4-H24 plate material was treated under the treatment solutions and treatment conditions shown in Table 6, washed with water, dried, and subjected to color measurement in the same manner as in Example 1 to obtain X,
The S value was calculated from the Y and Z values. Next, the test piece was coated with acrylic resin (Shinto Paint Co., Ltd., Svia AL-50B) to a coating film thickness of 1 μm, and baked at 290 ° C. to make 1,1,1-
7 in trichlorethane (Etana VG, Asahi Kasei Corporation)
It was immersed at 4 ° C. for 10 minutes. This part of the test piece was immersed in an aluminum fin cleaner (Shinwa Kogyo Co., Ltd. aluminum fin cleaner W 5-fold diluted solution, pH 12 to 13) at room temperature for 10 minutes, and then washed with running water for 15 minutes as one cycle. After the cycle treatment, a tight-fitting eye adhesion test (long-distance stitch 1 mm interval) was performed. Moreover, SST (JIS 2371-1988 compliant, 200
0 hours). Table 6 shows the results.

[0051]

[Table 6]

[0052]

Industrial Applicability The present invention has found that it is possible to determine an appropriate condition from the processing conditions which have hitherto relied on experience and intuition, by a colorimetric measurement which can be performed easily and quickly and nondestructively. While determining this condition, an effective composition of the processing solution was proposed.

It has been clarified that the treatment of an aluminum material with this treatment solution is not only effective as a treatment having corrosion resistance by itself, but also an extremely effective pretreatment as various conventionally known pretreatments.

That is, the color measurement can be performed nondestructively easily and in a short time by using a colorimeter such as a color meter. Suga Test Machine Co., Ltd. color computer SM-3
In the case of color measurement by, it is a few seconds / case, and naturally, it can be measured in the atmosphere. This is SEM, TEM or E
Definitely advantageous for measurement by PMA, XPS, etc. Accurate values can be easily obtained with these devices, but vacuum is required, and it is difficult to inspect non-destructively for large samples, and it takes a long time to measure, but relative values can be used sufficiently. It is a numerical value.

Further, in the surface treatment with the treatment liquid of the present invention, the surface oxide film can be completely removed in a short time, no smut is generated and no desmut treatment is required, and the bath and piping can be easily managed. As a pretreatment for corrosion resistant treatment such as hydration oxidation treatment, chromate treatment, anodic oxidation treatment, AC electrolysis in alkaline solution or resin coating, that aluminum material with beautiful appearance with good corrosion resistance can be obtained by just treatment. When used together, uniformity,
It is an excellent surface treatment method in that it can form a film excellent in discoloration prevention, adhesion, solvent resistance, and corrosion resistance.

[Brief description of the drawings]

FIG. 1 shows the relationship between color tone (S value) and surface oxygen concentration.

Front page continuation (72) Inventor Masahiro Kurata 4-3-18 Nihombashi Muromachi, Chuo-ku, Tokyo Sky Aluminum Co., Ltd. (72) Inventor Sadao Shiraishi 4-3-18 Nihonbashi Muromachi, Chuo-ku, Tokyo Sky Aluminum Stock In-company (72) Inventor Nobuyoshi Sasaki 4-3-18 Nihombashi Muromachi, Chuo-ku, Tokyo Inside Sky Aluminum Co., Ltd. (56) Reference JP 62-13583 (JP, A) JP 58-1078 ( JP, A) JP 5-195246 (JP, A) JP 5-195245 (JP, A) JP 2-186000 (JP, A) JP 62-4890 (JP, A) JP 59-133382 (JP, A) JP-A-53-140241 (JP, A)

Claims (4)

(57) [Claims] 1. A color tone (S) after surface treatment with an aqueous solution containing a chelating agent and a basic organic amine in a free state is S = (X ² + (3.388Z-3Y) ² ) ^1. Aluminum material characterized in that ^{/ 2} ≧ 70 (XYZ is the tristimulus value of color). 2. An aluminum material is used as a chelating agent 0.0
05 mol / l or more, 5 g / l or more of a basic organic amine in a free state is contained, a surface treatment is performed with an aqueous solution having a phosphate group concentration of 100 ppm or less and a sulfate group concentration of 500 ppm or less, and a color tone (S) is S = (X ^{2 + (3.388Z-3Y) 2} ) 1/2 ≧ 70 (XYZ surface treatment method of an aluminum material, which comprises processing until the tristimulus value) of the color. 3. An aluminum material is used as a chelating agent 0.0
1 mol / l or more, basic organic amines in a free state 5
Surface treatment is performed with an aqueous solution containing g / l or more and having a phosphate group concentration of 100 ppm or less and a sulfate group concentration of 500 ppm or less, and the color tone (S) is S = (X ² + (3.388Z-3Y) ² ) ^1/2 A surface treatment method for an aluminum material, which comprises performing another surface treatment after treatment until ≧ 70 (XYZ is tristimulus value of color). 4. The surface treatment method for an aluminum material according to claim 3, wherein the other surface treatment is a hydration oxidation treatment, a chromate treatment, an anodizing treatment, an alternating current electrolytic treatment, a coating of a resin paint or a combination thereof.