JPH05245437A - Organic coating Zn-based alloy plating Al alloy plate - Google Patents

Abstract

(57) [Summary] [Object] The main object of the present invention is to improve external rust resistance and lubricity after plating of an Al alloy plate and coating of an organic coating film. Plating Al
To provide an alloy plate. [Structure] One or both sides of an Al alloy plate is coated with a Zn-based alloy plating layer in an amount of 0.1 to 60 g / m ² , and a MoS ₂ having an average particle diameter of 0.5 μm or less is formed on the upper layer through a chromate film.
An organic coating containing 5 to 70 wt% of 0.01 to 0.5
An organic coating Zn-based alloy plated Al alloy plate having a thickness of μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic coated Zn-based alloy plated Al alloy plate, and more specifically, it has excellent corrosion resistance and lubricity, weldability, and electrodeposition paintability, and has various uses, for example, The present invention relates to an organic coating Zn-based alloy plated Al alloy plate applicable as an Al alloy plate for automobiles.

[0002]

2. Description of the Related Art In general, steel sheets for automobiles undergo various processes in the process of car body manufacturing, and therefore lubricity for pressing, weldability for joining parts, and electrodeposition paintability during painting are essential. It On the other hand, corrosion resistance is particularly required in the traveling environment of automobiles. From the viewpoint of corrosion resistance, not only bare corrosion resistance but also external surface rust resistance, perforation resistance, hot water immersion adhesion of coating film, red rust resistance and the like are required. For example, Japanese Patent Publication No.
Zn-Ni plated steel sheet seen in Japanese Patent Publication No. 29821, Zn-Fe2 seen in Japanese Patent Publication No. 56-133488.
The plated steel sheets that have been conventionally used such as the layer-plated steel sheet have excellent corrosion resistance, but there is no example in which such a plating is coated on the Al alloy sheet. Furthermore, the performance required from the user side is higher. However, there is room for improvement in the plating to be coated in terms of outer surface rust resistance and perforation resistance of processed parts. Further, a single-layer plated composite plated steel sheet found in Japanese Patent Publication No. Sho 58-247984 has been proposed, but its application to an Al alloy sheet is partially found in Japanese Patent Laid-Open No. 61-157693, but it is resistant to yarn rust. At present, it is not sufficient in terms of lubricity and lubricity.

[0003]

The inventors of the present invention have conducted various experiments in view of the above-mentioned circumstances, and as a result, on the surface of an Al alloy plate, Zn-based alloy plating was applied and, as an upper layer, chromate treatment was applied. It has been found that by adding an organic coating film containing MoS ₂ , the outer surface rust resistance and lubricity of the Al alloy plate are improved without impairing the weldability and electrodeposition coating property.
It is considered that the Zn-based alloy plating and the chromate film coated on the Al alloy plate suppressed the thread rust peculiar to the Al alloy plate and improved the outer surface rust resistance. It was also found that the lubricity is remarkably improved by thinly applying an organic coating film containing MoS _{2 on} the upper layer of the chromate film.

The present invention has been made on the basis of the above findings, and the gist thereof is as follows: (1) The amount of plating deposited as an underlayer is 0.1 to 60 g on one or both sides of an Al alloy plate. / M ² Zn-based alloy plating layer, with an average grain size of 0.
An organic coating Zn-based alloy plated Al alloy plate having an organic coating film containing 5 to 70 wt% of MoS ₂ of 5 μm or less in an amount of 0.01 to 0.5 μm. (2) The Zn-based alloy plating of the lower layer is Fe, Ni, C
1 to 90 wt% of one or more alloy elements selected from o, Cr, Al, and Mn are contained in the organic coated Zn-based alloy plated Al alloy plate of (1).

The present invention will be described in detail below. First, in the present invention, the organic coated Zn-based alloy plated Al alloy plate is composed of three layers including a Zn-based alloy plating, a chromate film and an organic coating film containing MoS ₂ as an upper layer, which will be described later. This has a three-layer structure because the outer surface rust resistance, lubricity, weldability, and electrodeposition coatability are taken into consideration at the same time, as described above. Here, the Zn-based alloy plating of the lower layer means Zn containing one or more alloy elements selected from Fe, Ni, Co, Cr, Al, and Mn.
System alloy plating, and the alloy element content is 1 to
90%. The reason for using these platings is that Al and Fe tend to cause thread rust, whereas Zn-based alloy plating generally does not show thread rust and has better corrosion resistance than Zn single plating. It also has an excellent effect of suppressing. Therefore, coating the Al alloy plate with the Zn-based alloy plating is effective in improving the outer surface rust resistance. In addition, Zn-based alloy plating generally has a higher surface hardness than Zn single plating,
The coefficient of friction also tends to decrease. This effect is remarkable as compared with the original aluminum alloy plate. The lower limit of the alloy element content is Zn
The corrosion resistance is improved to 1% as compared with the single plating, and if it exceeds 90%, the alloy plating layer becomes too hard and the lubricity deteriorates, so this was made the upper limit.

The chromate directly on the plating may be basically any type such as electrolytic chromate, coating type chromate and reactive type chromate. The role of the chromate under the three-layer structure is important not only in the thread rust resistance but also in the viewpoint of improving the adhesion between the plating and the organic coating film. It can be said that these are known functions when considering the organic composite plated steel sheets developed so far. Furthermore, on the top layer, M
By imparting a thin organic coating film containing oS _{2, the} lubricity can be improved without impairing the weldability and electrodeposition coating property.

Here, the constitution and role of the organic coating film are explained.
Reveal MoS in the coating₂Is mainly used for electrodeposition
The purpose is to improve paintability during painting.
oS ₂Uses that it shows semiconductivity depending on conditions
Of. MoS with an average particle size of 0.5 μm or less in the coating film₂
The coating film containing 5 to 70 wt% has a thickness of 0 to 20 μm.
In the range, good electrodeposition coatability is exhibited. If necessary,
Conductive fine particles may also be used in combination. Examples of conductive particles
As for zinc oxide, tin oxide, conductive carbon, graph
And iron tetroxide. Contained as the amount to be used in combination
MoS₂Is preferably 0 to 50 wt% of the content of
5 to 20 wt% is desirable. MoS₂Increase the amount of
The energizing amount increases as the
The electrodeposition limit film thickness also increases, but if it exceeds 70 wt%, corrosion resistance
Cause a decrease in sex. As a resin to disperse these
As long as it is a resin generally used in coating compositions, there are no particular restrictions.
Absent. In addition, colloidal silica, flow regulator and coloring
Pigment, anti-foaming agent, dispersant, anti-settling agent, blocking
Do not cover pigment additives used in general paint such as inhibitors.
It can be used as long as the characteristics of the covering are not impaired.

Although MoS ₂ is generally known as a solid lubricant, the same effect was observed in the coating film. The reason why the average particle size of MoS ₂ is limited to 0.5 μm or less is that the particle size of 0.5 μm or more is not preferable in appearance and causes workability defects such as mold galling, and is preferably less than the coating film thickness. To do. The MoS ₂ -containing organic coating film had a coating thickness of 0.01 μm or more and was found to have very good lubricating properties. Furthermore, since the upper coating film of the organic coating Zn-based alloy-plated Al alloy plate of the present invention has a very small current at a low voltage, it exhibits good corrosion resistance and good electrodeposition coating property. Good weldability is essential for determining the effective range of the coating thickness. Of the weldability, the continuous spotting property is particularly important, but an increase in the coating thickness leads to a decrease in the continuous spotting property. When the thickness of the upper coating film of the present invention exceeds 0.5 μm, the spotting property is remarkably lowered. Therefore, the upper layer film thickness is set to 0.5 μm or less.
Hereinafter, the effects of the present invention will be described more specifically with reference to Examples.

[0009]

EXAMPLES The production of the plated Al alloy plate of the present invention was conducted at pH 1
˜3 fluoride bath or pH 13.5-14.5 alkaline bath and pH 1-3 sulphate bath,
It is possible by performing electroplating using a chloride bath.
However, in the examples shown below, the electroplating conditions are a current density of 10 to 200 A / dm ² and a line speed of 10
˜250 m / min. The base Al alloy plate was mainly based on 5000 series and 6000 series. Ordinary electrolytic chromate treatment (Total Cr) is applied to the upper layer of the plating.
60 mg / m ² ). For organic coating, the following coating composition was applied with a bar coater.

(1) MoS _{2 having} an average particle diameter of 0.5 μm or less (manufactured by Moly Powder PA Sumiko Lubricant) (2) SiO ₂ (manufactured by Mizukasil P-526 Mizusawa Chemical) (3) Phenoxy resin (ESRP #
250 20% liquid manufactured by Sumitomo Chemical Co., Ltd. (4) Butylcellosolve (5) Methylethylketone (6) Dispersant However, the compounding ratio was appropriately changed with changes in film thickness and MoS ₂ content.

The evaluation tests include flat plate pull-out test (friction coefficient measurement), yarn rust resistance test (thread rust occurrence), continuous spotting property test (spotting number, dust occurrence), electrodeposition paintability test (surface smoothness appearance observation). I went. The test conditions are shown below. [Plate drawing test condition] Specimen size: 1.0 mm x 30 mm x 300 mm Pressing force: 450 kgf Drawing speed: 200 mm / min Tool contact area: 900 mm ² (30 mm x 30 mm)

[Test Conditions for Thread Rust Resistance] Specimen size: 1.0 mm × 70 mm × 150 mm Sample preparation: A plating aluminum plate was subjected to chemical conversion treatment + 3 coats, and then scratches reaching the base of coating were added. Test environment: salt spray + wet environment.

[Conditions for continuous spotting test] Electrode: Tip C type 4.5 mmφ Pressurization: Based on 200 kgf Energization time: 10 cycles Energization condition: Use of proper welding current Measurement of nugget diameter and dust by peel test as evaluation of number of spots The occurrence is observed and judged.

[Conditions for Electrodeposition Paintability Test] Species: Epoxy-based cation type electrodeposition coating type Electrodeposition conditions: 200V, 3min Baking conditions: 180c, 30min Coating thickness: 20 ± 2 μm

Further, the evaluation criteria of each test are as follows.

[0016] However, thread rust occurs from the cut scratches.

[0017]

[0018]

In the present invention, the lower layer is made of Zn--Fe (10-5).
0%), Zn-Cr (5-30%), Zn-Ni (1-
40%), Zn-Al (1-80%), Zn-Fe (5
~ 85%)-Cr (1-5%) Zn-based alloy plating is applied, and the upper organic film contains 20 wt% of MoS ₂ .
FIG. 1 shows the relationship between the amount of Zn-based alloy plating deposited and each evaluation test when the thickness is 5 μm, and the lower layer is Zn—Co (1-40
%), Zn-Fe (1 to 70%), Zn-Fe (1 to 1)
5%)-Al (10-30%), Zn-Fe (1-50)
%)-Co (1 to 5%), Zn-Ni (1 to 90%) Zn-based alloy plating deposition amount 1 g / m ² , organic film thickness 0.5
FIG. 2 shows the relationship between the MoS ₂ content in the organic film and each evaluation test in the case of μm. As a lower layer, Zn-Co (20-5
0%), Zn-Ni (1-30%)-Cr (5-10)
%), Zn-Fe (1 to 90%), Zn-Mn (1 to 5)
0%), Zn-Al (1 to 70%) Zn-based alloy plating adhesion amount 10 g / m ² , and MoS ₂ content in the organic film is 2
FIG. 3 shows the relationship between the organic coating thickness and each evaluation test when the content is 0 wt%. (Moisture), (Melting), (Rust) in the figure
The symbols on the vertical axis of (electrification) indicate lubricity, continuous spotting property, yarn rust resistance, and electrodeposition coating property.

From FIG. 1, Zn-based alloy plating of 0.1 g /
When applied over m ² , no thread rust is observed, 60 g /
It can be seen that if it exceeds m ² , lubricity deteriorates. From FIG. 2, the content of MoS ₂ is 5 to 70 due to the limitation of the electrodeposition coatability.
It is considered appropriate to set it as wt%. From FIG. 3, the lower limit of the organic film thickness is 0.01 μm from the lubricity and the upper limit is 0.5 μm from the weldability as well, and this range is a suitable film thickness. From the above, the Zn-based alloy plating layer was 0.1
-60 g / m ² and an upper layer having an organic coating of 0.01 to 0.5 μm containing ₅ to 70 wt% of MoS ₂ having an average particle size of 0.5 μm or less through a chromate coating.
It was confirmed that the l alloy plate is suitable for improving the lubricity and the outer surface rust resistance.

[0021]

INDUSTRIAL APPLICABILITY As described above, the present invention relates to the organic coated Zn-based alloy-plated Al alloy sheet which is extremely excellent in rust resistance and lubricity after plating of the Al alloy sheet and coating of the organic coating film. The industrial significance is that it can be applied as an Al alloy plate for lightweight automobiles.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a Zn-based alloy plating deposition amount and each evaluation test according to the present invention.

FIG. 2 is a diagram showing the relationship between the MoS ₂ content in the organic coating film according to the present invention and each evaluation test.

FIG. 3 is a diagram showing a relationship between an organic coating film thickness and each evaluation test according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C25D 3/22 5/30 (72) Inventor Kazuhiko Honda 20-1 Shintomi, Futtsu-shi, Chiba Made in New Japan Steel Co., Ltd. Technology Development Division

Claims (2)

[Claims] 1. An Al alloy plate has a Zn-based alloy plating layer having a coating amount of 0.1 to 60 g / m ² as a lower layer on one or both sides, and an average particle size of 0.5 μm through a chromate film on the upper layer. An organic coating Zn-based alloy-plated Al alloy plate having an organic coating film containing ₅ to 70 wt% of MoS ₂ below in an amount of 0.01 to 0.5 μm. 2. The Zn-based alloy plating of the lower layer is Fe, N
The organic-coated Zn-based alloy-plated Al alloy plate according to claim 1, which contains 1 to 90 wt% of one or more alloy elements selected from i, Co, Cr, Al, and Mn.