JPH0790608A - Surface treated aluminum sheet excellent in spot resistance weldability and workability - Google Patents

Abstract

PURPOSE:To produce a surface treated aluminum sheet in which higher workability has been secured and sufficient corrosion resistance and spot resistance weldability can be maintained. CONSTITUTION:On the surface of an aluminum sheet in which the surface oxidized film thickness is regulated to <=150Angstrom , as a primary layer, an organic mixture layer contg. 100 pts.wt. resin contg. a hydrogen group and/or a carboxyl group and one or >=two kinds among Ti, Zr, Mo, V, W and Mn in the shape of metallic compounds by 5 to 100 pts.wt. is formed by 10 to 300mg/m<2> coating weight. Furthermore, on the surface, an organic resin layer of an organic resin mixture contg. 5 to 40 pts.wt. carbon black having >=800m<2>/g specific surface area to 100 pts.wt. organic resin and moreover contg. 1 to 30 pts.wt. powdery lubricant is formed by 0.05 to 3.0mum as a dry film thickness. The powdery lubricant is constituted of wax and/or fluorocarbon resin having 0.05 to 10mum average grain size, and the average grain size is regulated to 1.0 to 10 times the same dry film thickness.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a surface treatment of an aluminum plate, which is processed mainly by press forming and spot resistance welding, for automobiles, home appliances, building materials, cans, etc., which has significantly improved workability and weldability. The present invention relates to an aluminum plate (also widely including an aluminum alloy plate).

[0002]

2. Description of the Related Art Aluminum plates (including aluminum alloy plates) are widely used in the fields of automobiles, home appliances, office automation equipment, building materials, can materials and the like, and various press workings are carried out in the manufacturing process of these products. And often subject to spot resistance. Lubricant is usually applied to the surface of the aluminum plate during press working, but this work has the following problems.

(1) Lubricating oil cannot prevent the occurrence of mold galling during press working. (2) Lubricating oil is often applied by spraying, and the lubricating oil is scattered around, which deteriorates the working environment. (3) It needs to be degreased and washed in order to be incorporated as a product after press working, but in this process there is a risk of lowering the working environment and causing environmental problems (CFC, 1
-1-1 trichloroethane etc.) is used.

Therefore, there has been a demand for the development of an aluminum plate which can be press-molded without oiling and the degreasing process can be omitted. In JP-A-2-310036 and JP-A-3-180218), if the coating amount of wax is small, the workability is not sufficient, and if the coating amount is large, the mold is contaminated, and therefore it cannot be used in a wide range of fields, and Since the metal surface of the aluminum plate is exposed after the press working, there is a case where the corrosion resistance becomes problematic when used as it is. Further, the application of these solid lubricants has a drawback that the spot resistance weldability is remarkably deteriorated.

[0005]

In the conventional method for improving the workability by applying these waxes, it is difficult to obtain a stable effect under various molding conditions, and the post-processing coating is applied depending on the use environment. It is difficult to omit the washing step after processing because there is a risk of rusting unless other anticorrosion treatment is applied.

[0006] Therefore, in order to overcome these drawbacks of the prior art, it is an object of the present invention to provide a surface-treated aluminum plate which can secure higher workability and can retain sufficient corrosion resistance and spot resistance welding. To do.

[0007]

As a result of intensive studies to overcome these conventional techniques, the present inventors have found that after adjusting the oxide film thickness of the aluminum surface to 150 Å or less, Ti, A resin containing carbon black having a specific surface area of 800 m ² / g or more and lubricating fine particles, on which an organic mixture layer containing one or more of Zr, Mo, V, W and Mn in the form of a metal compound is formed. It was discovered that sufficient workability and spot resistance weldability can be ensured and corrosion resistance can be retained by forming a layer, and the present invention has been completed.

That is, according to the first aspect of the present invention, 100 parts by weight of a resin containing a hydroxyl group and / or a carboxyl group as the first layer, and Ti on an aluminum plate whose surface oxide film thickness is adjusted to 150 Å or less. , Zr, Mo,
One organic compound mixture layer containing 5 to 100 parts by weight of one or more of V, W and Mn in the form of a metal compound.
Formed at a coverage of 0~300mg / m ^2, further to the organic resin 100 parts by weight thereon, the specific surface area of 800 m ² /
An organic resin layer having a dry film thickness of 0.05 to 3.0 μm is formed from an organic resin mixture containing 5 to 40 parts by weight of carbon black (g) or more and 1 to 30 parts by weight of a powder lubricant. Provided is a surface-treated aluminum plate which is excellent in spot resistance weldability and workability.

The powder lubricant has an average particle size of 0.05.
It is preferable that the wax and / or the fluorine-based resin have a thickness of 10 μm and the average particle diameter thereof is 1.0 to 10 times the dry film thickness.

[0010]

The present invention will be described in more detail below. The aluminum plate in the present invention broadly includes aluminum plates and aluminum alloy plates mainly for automobiles, home appliances, building materials, can materials, etc., which are processed by press forming and spot resistance welding.

In the present invention, in order to reduce the surface resistance of the above-mentioned aluminum plate and improve the spot resistance weldability, the oxide film thickness on the surface is adjusted to 150 Å or less. If the oxide film thickness exceeds 150Å, the surface resistance increases and sufficient weldability cannot be obtained.

As the oxide film adjusting treatment, a treatment for removing the surface alumina layer by an alkali etching treatment, a pickling treatment for mainly removing the magnesia layer in an acidic aqueous solution containing a mineral acid, or a treatment for performing pickling treatment after an alkali etching treatment Is used to remove most of the oxide layer on the surface.

As the alkali etching treatment and the pickling treatment, a method generally used as a treatment method for an aluminum material may be used, and a commercially available treatment liquid may be used. For example, caustic soda, caustic potash, etc. can be used for the alkali etching treatment, and sulfuric acid, nitric acid, hydrofluoric acid, a nitric acid + hydrofluoric acid mixed solution, etc. can be used for the pickling treatment.

In the present invention, the film formed as the first layer on the surface of the aluminum material after the oxide film adjustment treatment is an organic resin containing a hydroxyl group and / or a carboxyl group and Ti, Zr, Mo, V, W and Mn. It is composed of at least one metal compound selected from the group consisting of:

As the organic resin, a water-soluble acrylic resin such as polyacrylic acid or polymethacrylic acid resin is preferably used, but the organic resin is not limited thereto.

These organic mixed layers are necessary for improving the corrosion resistance and ensuring the adhesion between the upper layer and the base metal. If the metal compound is less than 5 parts by weight with respect to 100 parts by weight of the resin, the corrosion resistance is insufficient. Addition in excess of parts by weight may impair adhesion, so the amount was limited to 5 to 100 parts by weight. The coating weight is small, the effect is less than 10 mg / m ^2, the electric resistance exceeds 300 mg / m ² is then the risk of reducing the spot resistance weldability increases, limited to the range of 10-300 mg / m ² did.

Next, as the organic resin of the resin layer formed on the organic mixed layer, an epoxy resin, an alkyd resin, an acrylic resin, a urethane resin, a phenol resin, a melamine resin, which have good adhesion to a metal plate, One or a mixture of two or more kinds of polyvinyl butyral resin, polyester resin, or a copolymer is preferable. If the dry film thickness of these resin layers is less than 0.05 μm, sufficient workability cannot be secured, and if it exceeds 3.0 μm, it becomes difficult to secure weldability, so it is limited to the range of 0.05 to 3.0 μm. did. A more preferable range is 0.1 to 1.0 μm.

Next, the carbon black added to the organic resin layer will be described. If the specific surface area is less than 800 m ² / g, it is difficult to secure sufficient workability and weldability. If it is less than 5 parts by weight with respect to parts by weight, sufficient workability and weldability improving effects cannot be obtained.
The addition of more than 0 parts by weight lowers the cohesive force of the resin and facilitates powdering, so the specific surface area is 800 m ²
/ G or more, the addition amount was limited to 5 to 40 weight.

As the powdery lubricant added to the organic resin layer, it is preferable to use a synthetic wax, a fluorine resin or a mixture thereof. Examples of synthetic waxes include polyethylene wax, polypropylene wax, polybutene wax, and the like.

Examples of the fluorine-based resin include polytetrafluoroethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin and the like.

These lubricants have an average particle size of 0.05 to 1
It is preferably 0 μm and used in the range of 1.0 to 10 times the dry film thickness. If the average particle size of the lubricant is too small compared to the dry film thickness, the lubricity is insufficient, and if it is too large, the lubricant is likely to fall off and sufficient workability cannot be obtained. A more preferable range is 1.5 to 5 times the dry film thickness. As for the amount of addition, the addition of less than 1 part by weight to 100 parts by weight of the organic resin is not sufficient for improving the workability and lubricity, and the addition of more than 30 parts by weight reduces the cohesive force of the organic resin. Since there is a risk of powdering and a risk of lowering paint adhesion of the post-coating, the amount is limited to the range of 1 to 30 parts by weight.

[0022]

EXAMPLES The present invention will be specifically described below based on examples. (Example) As a test piece, a JIS 5182 alloy plate having a thickness of 1 mm, which is a typical aluminum alloy for processing, was used. First, the surface of the aluminum alloy plate was steam-degreased with trichlorethane, and then the oxide film adjustment treatment shown in Table 1 was performed. It was The oxide film thickness shown in the table is a value measured using ESCA.

Next, the above-mentioned aluminum plate was coated with the organic mixture shown in Table 2 by a spin coater, dried and baked at 120 ° C., and then treated with a resin. Table 2 shows the organic mixture treatment conditions, and Table 3 shows the resin treatment conditions. The organic mixture used in this example was a homemade product, and the following carbon black, organic resin and lubricant were used. The following tests and evaluations were performed on the obtained samples.

[0024] (carbon black); Mitsubishi Kasei Co., Ltd. CF9 specific surface area of 60m ² / g; Mitsubishi Kasei Co., Ltd. MA8 137m ² / g; Mitsubishi Kasei Co., Ltd. # 1000 200m ² / g; Mitsubishi Kasei Co., Ltd. # 2400 280m ² / g; Mitsubishi Kasei # 3750 800m ² / g; Mitsubishi Kasei # 3950 1500m ² / g; Ketjen Black EC 800m ² / g; Ketjen Black EC600JD 1270m ² / g; homemade acetylene black 560m ² / g The specific surface area is determined by the nitrogen adsorption method.

(Organic Resin) Epoxy Resin; Oiled Shell Epoxy Company Epicoat Alkyd Resin; Ulyx Acrylic Resin by Mitsui Toatsu Chemicals; Almatex 749 Urethane Resin by Mitsui Toatsu Chemicals; Orestar by Mitsui Toatsu Chemicals Phenolic resin; Super Beckasite melamine resin manufactured by Dainippon Ink and Chemicals; Uban butyral resin manufactured by Mitsui Toatsu Chemicals; Denka butyral polyester resin manufactured by Denki Kagaku; Almatex P645 manufactured by Mitsui Toatsu Chemicals Acrylic resin 50 parts by weight to 100 parts by weight of epoxy resin, epoxy + urethane resin 100 parts by weight of urethane resin to 100 parts by weight of epoxy resin, acrylic + urethane resin 100 parts by weight of urethane resin to 100 parts by weight of acrylic resin did

(Lubricant) Wax 1 San Nopco SL92 average particle size 27 μm Wax 2 San Nopco SL417 14 μm Wax 3 San Nopco SL530 6 μm Wax 4 San Nopco SL600 1.2 μm Fluoro resin 1 Asahi Glass AD1 8 μm Fluorine Resin 2 Lubron 0.2 μm manufactured by Daikin Industries, Ltd.

(Test of Workability and Evaluation Method) The workability of the test variation after the surface treatment was obtained by performing high-speed cylindrical drawing with a diameter of 33 mmφ (processing speed 500 mm / sec) without oiling and its limiting drawing ratio (LDR). Plane sliding test (200 kg / cm ² ,
The friction coefficient (μ) at 100 mm / sec) was used for evaluation. Evaluation by LDR Evaluation by μ ◎; LDR 2.12 or more ◎; 0.15 or less ○; 1.96 or more and less than 2.12 ○; 0.15 or more and 0.25 or less △; 1.90 or more and less than 1.96 △; 0.25 or more and less than 0.4 ×; less than 1.90 ×; 0.4 or more

(Welding Test and Evaluation Method) The electrode life of the aluminum alloy plate after the coating treatment was evaluated using an inverter DC welding machine under the following electrodes and welding conditions. The number of dots or nugget diameter before welding is 4√t
The effect was judged by the smaller number of RBIs, whichever is smaller than (t: plate thickness). The evaluation criteria are poor (x) when the number of hit points is less than 500, normal (△) from 500 to 1000, and good (◯) from 1000 to 1500.
Exceeding the point was rated as excellent (◎).

(Electrode) -Shape: Cone conical head (CF) type-Tip diameter: 5.0 mmφ-Material: Cu-Cr

(Welding conditions) -Pressure: 150 kgf-Initial pressurization time: 20/50 seconds-Electrification time: 6/50 seconds-Holding time: 5/50 seconds-Welding current: 15 kA

(Corrosion resistance test and evaluation method) The corrosion resistance of the sample was evaluated by the following thread rust test. First, a commercially available automotive cationic electrodeposition coating (U-600 manufactured by Nippon Paint Co., Ltd.) was applied to the sample 2
0 μm, intermediate coating (KPX50 manufactured by Kansai Paint Co., Ltd.) 35
A test piece (70 × 150 mm) with a top coat (B531 manufactured by Kansai Pain Co., Ltd.) of 35 μm was applied to ASTM D28.
According to the thread rust test method specified in No. 03, a cross-cut flaw reaching the base material was made and a test was conducted for 6 weeks. In the evaluation, when the maximum length of thread rust from the cross cut portion was 4 mm or more, it was evaluated as poor (x), 2 to 4 mm was rated as normal (◯), and less than 2 mm was rated as excellent (⊚). The results of the above evaluation tests are summarized in Table 4.

As is clear from Tables 1 to 4, according to the present invention, excellent workability, slidability, weldability,
Although the corrosion resistance is obtained, all the performances cannot be satisfied in the comparative examples which are out of the range of the present invention.

In Comparative Examples 1 and 2, the oxide film is too thick and the conductivity is remarkably poor. In Comparative Example 3, the content of the metal compound in the first layer is too small and the corrosion resistance is poor, and in Comparative Example 4, it is too large and the conductivity is significantly poor. In Comparative Example 5, the thickness of the first layer is too thin and the corrosion resistance is poor, and in Comparative Example 6, the thickness is too thick and the conductivity is significantly poor.

In Comparative Example 7, since the amount of carbon black added was small, the conductivity was remarkably inferior and the processing was slightly insufficient. In Comparative Example 8, since the addition amount of carbon black is excessive, the cohesive force of the resin film is reduced and sufficient workability and slidability cannot be obtained.

In Comparative Example 9, sufficient workability cannot be obtained due to the insufficient amount of the lubricant added, and in Comparative Example 10, the cohesive force of the resin film decreases due to the excessive amount of the lubricant, resulting in sufficient workability and sliding. I can not get sex.

In Comparative Examples 11, 12, and 13, since the specific surface area of carbon black is too small, sufficient conductivity cannot be obtained, and the workability and slidability are slightly insufficient.

In Comparative Example 14, the particle size of the lubricant was too small to obtain sufficient workability and slidability. In Comparative Example 15, the particle size was too large to easily fall off, so sufficient workability and slidability were obtained. Has not been obtained.

In Comparative Example 16, since the resin thickness is too large, sufficient conductivity cannot be obtained. In Comparative Example 17, since the resin thickness is too thin, sufficient workability and slidability are not obtained.

FIG. 1 shows the results of investigating the relationship between μ and the surface resistance value by changing only the specific surface area of carbon black under the treatment conditions of Inventive Example 1 and investigating the relationship. As is apparent from the above, it is clear that the slidability and conductivity are remarkably improved when the specific surface area is 800 m ² / g or more.

[0040] Alkaline etching: 5% NaOH solution, 3 at 60 ° C
Immersion for 0 seconds Nitric acid pickling: Immersion in 1: 1 diluted solution for 30 seconds at room temperature Sulfuric acid pickling: Immersion in 10% sulfuric acid solution at 50 ° C for 30 seconds

[0041]

[0042]

[0043]

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[0047]

[0048]

Industrial Applicability As described above, according to the present invention, an organic resin layer containing carbon black having a specific surface area of 800 m ² / g or more and a powdery lubricant is formed on the surface of a metal plate, thereby carrying out press working. Property, slidability and conductivity are remarkably improved. As a result, the productivity of home appliances, office automation equipment, automobile parts, etc. processed by press molding can be remarkably improved, and the oiling and degreasing steps can be omitted, which is very effective for environmental improvement. In addition, the spot resistance weldability is also significantly improved due to the significant improvement in conductivity.

[Brief description of drawings]

[Fig. 1] μ by changing the specific surface area of carbon black
It is a figure which shows the result of having investigated (Friction coefficient) and surface resistance value, and investigated the relationship with specific surface area.

Front page continued (72) Inventor Nobuo Totsuka No. 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Technical Research Division, Kawasaki Steel Co., Ltd. (72) Inventor Koji Uesugi 1 Kawasaki-cho, Chuo-ku, Chiba Address Kawasaki Iron & Steel Co., Ltd. Technical Research Headquarters (72) Inventor Naoki Nishiyama 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Iron & Steel Co., Ltd. Technical Research Headquarters (72) Inventor Koichi Hashiguchi Chiba Chiba Kawasaki Steel Co., Ltd., Chuo-ku, Chuo-ku, Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor, Emoto Namba 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Aluminum Co., Ltd.

Claims (2)

[Claims] 1. An aluminum plate having a surface oxide film thickness adjusted to 150 Å or less, 100 parts by weight of a resin containing a hydroxyl group and / or a carboxyl group as a first layer, Ti,
An organic compound mixture layer containing 5 to 100 parts by weight of one or more of Zr, Mo, V, W and Mn in the form of a metal compound is formed at an adhesion amount of 10 to 300 mg / m ² .
Further, a dry film thickness of an organic resin mixture containing 5 to 40 parts by weight of carbon black having a specific surface area of 800 m ² / g or more and 100 parts by weight of an organic resin, and further containing 1 to 30 parts by weight of a powdery lubricant. A surface-treated aluminum plate excellent in spot resistance weldability and workability, characterized in that an organic resin layer having a thickness of 0.05 to 3.0 μm is formed. 2. The powder lubricant has an average particle size of 0.05.
The surface-treated aluminum excellent in spot resistance weldability and workability according to claim 1, which is a wax and / or fluorine-based resin having a thickness of 10 μm and an average particle diameter of 1.0 to 10 times the dry film thickness. Board.