JPS6034772A - Painting method of metallic surface - Google Patents

Abstract

PURPOSE:To form an oxide film having excellent paint adhesion and corrosion resistance by coating alkoxide of >=1 kind among Si, Al, Ti, Ta and Zn on a metallic surface and subjecting the surface to a heating treatment. CONSTITUTION:A soln. prepd. by dissolving alkoxide of 1 or >=2 kinds among Si, Al, Ti, Ta and Zn in alcohol or ester is coated on a metallic surface and is thereafter heated to 100-600 deg.C. The oxide film of Si, Al, Ti, Ta and Zn used is obtd. on the metallic surface by such treatment. The thickness of said oxide film varies with the density and coating amt. of the alkoxide. Said film has poor adhesion and is liable to crack when the thickness exceeds 10,000Angstrom and the film loses the corrosion resistance at <100Angstrom and therefore the thickness is held in a 100-10,000Angstrom range. The film in which a part of the hydroxyl group and/or alkoxy group remains is formed and the adhesion to a paint is improved with the lower heating temp.

Description

[Detailed description of the invention] Technical field to which the invention relates This invention relates to a method for coating metal surfaces.

Prior Art When painting metal surfaces, it is well known that the quality of the substrate preparation affects the durability and finish quality of the paint film, and various treatment methods have been proposed. Examples of this endogenous surface treatment include the following methods, as described in the "Painting" chapter of the Metal Surface Technology Handbook.

1. Chemical conversion treatment method (a) Phosphate film treatment (e.g. Bonderite@8
004. Formation of a chemical conversion film manufactured by Nippon Parkerizing Co., Ltd. (trade name).

(b) Oxalate film treatment (for example, formation of a chemical conversion film under the trade name Granodo SS, manufactured by Nippon Paint).

(c) Chromate film treatment (e.g. Bonderite + 8
855, Nippon Vercalizing Co., Ltd., product name: Formation of chemical conversion film).

2. Sandblasting method However, among these conventional surface treatments, (1) chemical conversion treatment method does not provide sufficient adhesion to metals such as stainless steel and aluminum, and it is difficult to coat iron. Sufficient corrosion resistance cannot be obtained after the film is damaged. It also causes waste liquid pollution. Furthermore, (2) the sandblasting method has insufficient adhesion and corrosion resistance, and also causes noise and dust pollution.

In addition, there was a problem in that the material was deformed, and a satisfactory coating could not be achieved even with any surface treatment.

DISCLOSURE OF THE INVENTION This invention was made by focusing on the above-mentioned conventional problems, and includes silicon (Si) and aluminum (Aj?) on the metal surface.
), titanium (Ti), tantalum ('ffa), and zinc (Zn).

The present invention relates to a method for painting a metal surface, which is characterized in that it is then painted.

In the metal surface coating method of the present invention, the metal surface is first subjected to a base treatment, and for this purpose, Si, AI! .

After applying a solution of one or more alkoxides of Ti, Ta, and Zn dissolved in alcohol or ester to the metal surface, the temperature is 109 to 600°C.
Heat to temperature. By this treatment, an oxide film of one or more of the used Si, At, Ti, Ta, and Zn is obtained on the metal surface, and the base treatment is performed.

The method for applying the alkoxide solution in this base treatment may be any of spraying, dipping, brushing, roll coating, and the like. The metal coated with the alkoxide solution in this way is then heated at a temperature of 100 to 600°C, and the heating atmosphere is air, argon (Ar) gas,
Any gas such as nitrogen (N2) gas may be used. The thickness of the oxide film obtained by this heat treatment varies depending on the concentration of alkoxide and the amount of coating, but if it is thicker than 10,000 amps, the adhesion will be poor and cracks will occur easily, while if it is less than 100 amps, the corrosion resistance of the film will be poor. Since there will be no more people, the number will be in the range of 100 to 10,000 people. However, when heating the alkoxide solution after applying it, the lower the temperature, the better the adhesion to the paint because a film with some of the hydroxyl groups and/or alkoxy groups remains.

Further, the thickness of this oxide thin film can be freely controlled by adjusting the coating method, and the properties of the surface film can be freely selected by baking at a temperature of 1 hour after coating. For example, when coating a metal material by immersing it in a predetermined metal alkoxide solution and then pulling it up, a calibration curve showing the relationship between pulling speed and film thickness is created in advance through experiments, and the desired value is determined from this curve. A desired film thickness can be obtained by pulling at a speed corresponding to the film thickness.

The oxide film obtained by the surface treatment as described above has excellent adhesion to the base metal surface and top coat, corrosion resistance, etc.

In the method of this invention, a paint is then applied to the metal surface that has been subjected to the above-mentioned surface treatment. The coating method can be carried out by any conventional method, and it is noteworthy that the oxide film formed by the base treatment is thin so that electrodeposition coating is possible. Further, since the metal material prepared by the method of the present invention can be welded and formed (pressing and rolling) in the same manner as conventional methods, the coating step can be carried out completely separately from the surface treatment step. For example, manufacturers of materials such as steel plates, stainless steel, and aluminum perform surface treatment upon shipment, and users of these materials can apply paint as is or through a simple cleaning process without performing any pretreatment steps up to the surface treatment. It is.

In addition, the paint film after painting has an oxide film with excellent adhesion and corrosion resistance between the paint film and the metal surface, so it is highly durable and is resistant to corrosive liquids, such as when the paint film is scratched. Since the oxide film is inert, it will not be leached or deteriorated by oxidation, and the coating will not blister or peel.

Embodiments of the invention Example 1 Stainless steel (SUS 480. SUS 804)
, Aluminum (ASTM 5050) and Ordinary@
(5 pao) plate (thickness 1.0-2.0 mm, width '10 mm, length 150 mm).

As shown in No. 16, a 5% ethanol solution of Si, Ti, or Ta ethoxide was applied, and then baked at 100° C. for 15 minutes. Also for comparison, Bonderai) + 800
Phosphate film treatment by 4, Bonderite + 8855
Surface treatment was performed by chromate coating, electrogalvanizing, shot peening, or sandblasting.

Next, each sample was subjected to cationic electrodeposition coating under the following coating conditions. First, the surface-treated sample was immersed in a 0.1% solution of Nirasannonion NS-206 at 60°C to degrease it, immersed in deionized water at 60°C, and then sprayed with fresh deionized water at room temperature and rinsed. After, after draining 105-110
It was dried at ℃ for 5 minutes. Aqua 44200 dry sample
(manufactured by Nippon Oil & Fats Co., Ltd., product name) in a bath at a temperature of 27℃.
140 min (total immersion time) for 5 pca
Voltage 100 for V, 5US480 and 804
V. For ASTM5050, electrodeposition was applied at 140V and then baked at 170°C for 80 minutes. Each sample coated in this way was evaluated for initial performance, moisture resistance, hot water resistance, corrosion resistance, and heat resistance according to the following methods, and the results are shown in Tables 1 and 2.

Evaluation method: Based on stepping stone test SAE J400. 15,9mm for the test piece
Approximately 260 to 800 wet road stones of a size that can pass through a 95 mrn wide net but cannot pass through a 95 mrn net are blown with compressed air at about 70 pSi, and the state of the scratches is examined.

Impact resistance: Based on DuPont impact test. Apply an impact with a 5009 weight with a diameter of 12.7 mm (in inches) from a distance of 80 crn and check for cracks.

Adhesion test: 100 l mm squares on the coating surface
When you make a grid of individual pieces, stick cellophane adhesive tape on it, and immediately peel off the tape,
Inspect the painted surface for peeling.

A T-shaped cross cut is made in the center of a rectangular sample, placed on a mandrel with a diameter of 20 rryB evenly on the left and right sides, and both sides are bent 1800 degrees along the mandrel. Examine the flexibility of.

Humidity resistance: Maintained in an atmosphere of 50°C and relative humidity of 98% for 120 hours.

Moist water resistance It was immersed in warm water at 60°C for 7 hours, and after 24 hours of pulling it up, it was subjected to a second eye test.

Corrosion Resistance Test Salt Water Spray: Salt water spray test according to JIS Z2871, spraying for 144 hours or 800 hours with an X-shaped cross cut.

Heat resistant heat cycle, 2 cycles, with NESMO1aZ No. 8 coating.

Tables 1 and 2 show that the coating film coated by the method of the present invention is superior to the coating film obtained by electrocoating after conventional surface treatment.

Example 2 Plate thickness 0.471177!1 width 70tTtrn, length L
50m, m stainless steel plate (material JIS SUS 8
04) was coated with a coated stainless steel plate capable of resistance welding, which was produced by subjecting the coated stainless steel plate shown in Table 8 to the first coated stainless steel plate.
As shown in the figure, they were overlapped and resistance welded (seam welded), and the strength and corrosion resistance of the welded parts were examined. In Figure 1, 1
2 is painted surface, 2 is stainless steel @ base material (SUS 804)
, 8 indicates a melted part (nugget).

As a top coat, I used a recon polyester paint (trade name: Super Lac D-FS-81 manufactured by Nippon Paint Co., Ltd.) with excellent weather resistance, but in order to provide the electrical conductivity necessary for resistance welding, Stainless steel powder (
Material: JIS SUS 804) Mixed and applied.

For comparison, epoxy paint (product name:
Superlac DIFP-01 (manufactured by Nippon Paint Co., Ltd.) was completely undercoated, and a baked top coat was applied and baked to serve as a comparative test sample.

The strength and corrosion resistance of the welded parts of these samples were evaluated by the following methods, and the results are shown in Table 4.

Evaluation method Strength of welded part: Tested by shear test method.

That is, as shown in Figure 2, the width is 25 mm and the length is 200 mm.
A tensile load in the direction of the arrow was applied to a shear test piece with a thickness of 0.4 mm and the force required to break was measured.

Corrosion resistance...width 70 mm, length 100 mm as shown in Figure 8
mm.

It has a weld bead 4 at the center with a thickness of 0 and 4 mm.

A test piece provided with Sealant 5 was immersed in an aqueous sodium chloride solution at 50° C., and evaluation was made by examining the degree of rusting after 500 hours and 1000 hours. The sealant 5 is used to prevent rust from forming on the green test piece, and is Shin-Etsu Silicone KE 45- manufactured by Shin-Etsu Chemical Co., Ltd.
1 (product name) was used.

As mentioned above, in the comparative example, by applying an epoxy paint as an undercoat with a film thickness of 5 μm according to the conventional method,
Since the adhesion between the top coat and the base material is ensured, a pressure of 850 mm is required to perform resistance welding through this coat.
kgf, it is necessary to seam weld at a welding current of about 7.0 KA, and l! 50kgf, 5. At around OKA, sufficient strength cannot be obtained, and the weld will break at a load of around 214 kf. Also, the pressurizing force is 850 mm, and the welding current? , OKA
In this case, the welding process is perfect, but the strength near the weld is relatively weak due to carburization from the paint and the effects of heat during welding, and the weld will break at a load of about 588 kg.

On the other hand, in the case of the example, Si, kl, Tj,
Also, because the base treatment is performed to form a Ta oxide film, the electrical resistance is extremely low and the pressing force is 250 k.
pf and a welding current of 5.0 KA, sufficient welding is possible, and there is little carburization or thermal influence, so strong strength can be obtained.

850kff again? , UKA strength is also superior to that of the comparative example. On the other hand, regarding corrosion resistance, in the case of the example, damage to the coating film due to welding and thermal effects can be relatively reduced compared to the case of the comparative example.

Excellent corrosion resistance near welds.

Example 8 Stainless steel (SUS GO4 and SUS 48G) and ordinary steel plates with a thickness of 0.4 mm were coated with the same epoxy paint as in Example 2 as an undercoat and phosphate film treated (Bonderai #11004). Or Si, At + Ti or T similar to Example 2
After applying the a-based oxide film, a silicone polyester paint similar to that used in Example 2 was applied as a top coat by baking. A test piece of 11 oxllomm was cut out from these coated steel plates, and b = 20~ from one end as shown in Figure 4.
At the 80 mm position, bend it into a U shape with the painted side outside (
The inner early diameter of the bent portion R = 1 or 2 mm) was gently bent at a position d - approximately 39 mm from the opposite end. Note that a = 110 mm and C = approximately 50 mm. These test pieces were mounted on an atmospheric exposure test stand facing south (with the exposed surface tilted at 46 degrees to the horizontal) with the convex bends facing upward, and after 6 months, the bends, etc. were observed. The invitation status was investigated and the results obtained are shown in Table 5 below.

As shown in Table 5, the oxide film used as the base treatment for all test pieces painted using the method of the example has good adhesion and corrosion resistance. It can be seen that the workability and corrosion resistance are equivalent to those of the phosphoric acid film treatment of the comparative example.

As explained in detail about the invention, the coating method of this invention applies Si, AJ? , Ti, Ta, Zn (7) An alkoxide solution of one or more of Neuss is applied and heated to perform a base treatment, and a top coat is applied on top of this, and the metal obtained by the base treatment It has good adhesion between the oxide film and metal, as well as between the metal oxide film and paint film, and has excellent corrosion resistance.The film is extremely thin, so it can be electrodeposited, and it can be welded and formed. Deaυ,
Furthermore, the effects of reducing pollution and reducing painting costs can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the coated stainless copper plate resistance welded in Example 2, Figure 2 is a perspective view of the test piece used in the shear test in Example 2, and Figure 8 is the one used in the corrosion resistance test in Example 2. FIG. 4 is a perspective view of the sample used in the test of Example 8. 1... Painted surface 2... Stainless steel material (SUS 804) 8...
- Melted part (nugget) 4... Weld bead 5... Silicone sealant 6... Mounting hole. Continued from page 1 O Inventor Ishii Rules of the Association @ Inventor Tadahiko Morigaki @ Inventor Sueko Kobayashi 0 Inventor Shigeru Kotani @ Inventor Honaga Saito @ Inventor Nishi 1) Eiji Atsugi City, Okatsukoku 560-2 Nissan Motor Co., Ltd. Inside the Technical Center Co., Ltd. 560-2 Okatsukoku, Atsugi City Inside the Nissan Motor Co., Ltd. Technical Center 2-1 Minato-cho, Joetsu City, 1-1 Akihito Nippon Stainless Steel Co., Ltd. Naoetsu Research Institute 2-1 Minato-cho, Joetsu City, 1-Asako Nippon Stainless Steel Co., Ltd. Hara-shi, Naoe City Ariaki Taito 2-4

Claims (1)

[Claims] L Silicon, aluminum, titanium on the metal surface. 1. A method for coating a metal surface, which comprises applying a solution containing one or more alkoxides of tantalum and zinc, heating to provide a base treatment, and then applying a paint.