JPH10305519A - Surface coating structure of metal material and forming method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a wet metal plated layer without the need of polishing the ground of metal material by forming a metal surface with at least one layer of a resin coated layer formed on the ground of a metal material and at least one layer of the wet metal plated layer of a metal or a metallic compound formed thereon. SOLUTION: This is formed of at least one layer of a resin coated layer 3 formed on the ground of a metal material 1 and at least one layer of a wet metal plated layer 5 of a metal or a metallic compound formed on the coated layer 3. In order to improve the adherence between the coated layer 3, metal material 1 and the wet metal plated layer 5, a primer layer 2 of resin or a primer layer 4 of resin can be formed between the coated layer 3 and the metal material 1, or between the coated layer 3 and the wet metal plated layer 5. In this case, the coated layer 3 or primer layer 2 is formed directly without the need of polishing the ground surface of the metal material 1, and for the coated layer, there is used a paint having fine matters mixed therein such as aluminum so as to allow its outermost layer to have conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a surface coating structure of a metal material (for example, a light alloy wheel) including a wet plating layer, and a method of forming the same.

[0002]

2. Description of the Related Art Metallic materials such as light alloy wheels (hereafter, aluminum is used as an example, aluminum alloys, magnesium alloys, etc.), for which design is important, are placed on the surface of a base material in order to ensure brilliancy. At least one layer of metal plating having an outermost surface of chromium is applied. This plating, conventionally,
Usually, it is formed by wet plating, and in some cases, may be formed by dry plating such as sputtering. When wet plating is performed on a metal substrate, the substrate surface is polished to a smooth surface by buff polishing or the like in order to secure glitter. Ni if the surface to be plated is iron
Corrosion resistance is obtained by plating in two layers and then one layer of Cr thereon, but when the base material is an aluminum alloy (the same applies to a magnesium alloy), the plating material (Ni, Cr) Because the difference in ionization tendency is large, when the flaw penetrates the plating layer and reaches the substrate, it causes electrolytic corrosion when rainwater is applied, corrosion of the substrate, blistering of the plating layer,
Peeling of the plating layer occurs. To prevent this,
The required corrosion resistance is obtained by applying Cu plating as a bridge between the nickel plating layer and the substrate.

[0003]

However, the conventional method has the following problems. In the case of forming a plating layer by wet plating, it is necessary to polish a substrate to secure glitter. In addition, when the metal material is a wheel, the surface of the wheel is complicatedly curved, and the polishing cannot be automated, and must be performed manually, so a great deal of manpower and time is required for polishing, resulting in an increase in cost. . In addition, manual polishing requires maintenance in the working environment. Further, even if a tie layer of Cu is provided, it is difficult to completely secure corrosion resistance against electric corrosion, and a multilayer or thick film plating is required as a countermeasure, resulting in further cost increase. In the case of dry plating, since the plating is performed by sputtering or the like and the thickness of the plating layer is as thin as about 1 μm, there is a problem in flaw resistance and chipping resistance. An object of the present invention is to provide a surface coating structure of a metal material capable of forming a wet plating layer without requiring polishing of a metal material base, and a method of forming the same.

[0004]

The present invention to achieve the above object is as follows. (1) A metal material comprising at least one resin coating layer formed on a metal material base and at least one metal or metal compound wet plating layer formed on the resin coating layer Surface coating structure. (2) A step of forming at least one resin coating layer on a metal base material, and a step of forming at least one metal or metal compound layer on the resin coating layer by wet plating. A method for forming a surface coating structure of a metal material.

In the method (1) for forming the surface coating structure of the metal material and the method (2) for forming the surface coating structure of the metal material, a resin coating layer is formed under the plating layer. Even if the smoothness is low, the surface of the resin coating layer has smoothness, so it is not necessary to perform the polishing of the base material of the metal material, which has been conventionally performed, a great deal of manpower was spent on it,
Time can be saved, and costs can be reduced. In addition, with regard to corrosion resistance, which was difficult to secure with conventional wet plating, the resin coating layer covers the light alloy base surface, preventing the base from corroding.
Peeling is also prevented. Further, since the wet plating layer can be easily formed thick unlike the dry plating (in the case of 1 μm in the dry plating, it is easily changed to 15 μm in the wet plating).
４０40 μm), and by forming it thickly, and by the hardness of the plating that is the surface layer, the flaw resistance is greatly improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a surface coating structure of a metal material according to an embodiment of the present invention comprises at least one resin coating layer 3 formed on a base material of a metal material 1, and a resin coating layer. Layer 3
And at least one metal or metal compound wet plating layer 5 formed thereon. In order to improve the adhesion between the resin coating layer 3 and the metal material 1 and the wet plating layer 5, a resin primer layer 2 is provided between the resin coating layer 3 and the metal material 1; A resin primer layer 4 may be formed between the plating layer 5 (the primer layers 2 and 4 are not essential layers). In this case, the resin coating layer 3 or the primer layer 2 is formed directly on the surface of the base material without polishing the base surface of the metal material 1. The metal material base may be a metal (including alloy) base, and is made of, for example, an aluminum alloy, a magnesium alloy, iron, or the like. Metal material 1 is an arbitrary member made of a metal (including an alloy), for example, an aluminum alloy wheel.

The outermost layer of the at least one resin coating layer 3 must be a conductive layer so that a metal or metal compound layer 5 can be formed thereon by wet plating. This is a layer formed by coating a paint in which conductive fine substances such as carbon are mixed. The at least one resin coating layer 3 is a coating method, a single layer or a plurality of layers, and a resin material, as long as the resin coating layer 3 fills the minute irregularities of the base material of the metal material 1 and makes its outer surface smooth. , Thickness are arbitrary.

Accordingly, the coating methods include electrodeposition coating, electrostatic coating, powder coating, air spray coating, dipping,
Any of these may be used. In the case of a multi-layer configuration,
The coating method of each layer may be changed such that the lower layer is an electrodeposition coating and the upper layer is a powder coating. In general, the electrodeposition coating can fill the unevenness of the underlayer even if it is minute, has good adhesion to the underlayer, and has a large layer hardness. Powder coating and air spray coating can fill the unevenness of the underlayer relatively quickly when it is relatively large, the layer thickness is relatively large, and the coating film can be formed in a relatively short time . In order to satisfy both the adhesion to the base and the formation of a relatively thick layer in a short time, a composite coating in which the lower layer is an electrodeposition coating and the upper layer is a powder coating may be used.

The paint used for forming the layer 3 includes, for example, polyester resin paint, epoxy resin paint, acrylic resin paint, polyurethane resin paint, alkyd resin paint, aminoalkyd resin paint, silicone and fluororesin paint, vinyl resin Paints, water-soluble paints, powder paints, high solid paints, and the like.

The thickness of the layer 3 is required to be about 10 μm or more in order to fill the unevenness of the base and smooth the surface thereof. Further, when the metal material 1 is an aluminum wheel, if the thickness of the layer 3 is about 10 μm or more, the unevenness of the base can be almost completely covered, and the convex portion of the base protrudes outward from the layer 3. Instead, contact between the base and the plating 5 can be prevented (electrolytic corrosion prevention). In this sense, the thickness of layer 3 is about 1
It is desirable that the thickness be 0 μm or more. Further, from the viewpoint that the flaw can be further prevented from reaching the base when the flaw penetrates the plating layer 5 and reaches the layer 3, the larger the thickness of the layer 3, the better. In order to suppress the occurrence of microcracks in the plating layer 5 due to the difference in thermal expansion, it is preferable that the thickness is larger (for example, about 80 μm or more). Conversely, if the thickness of the layer 3 is too large, It is desirable that the thickness of the layer 3 be about 150 μm or less, especially about 8 μm, because it takes time and cost, and the shape of the underlayer cannot be sharply expressed in appearance.
It is desirable that the thickness be about 0 μm to about 150 μm.

When at least one metal or metal oxide layer 5 is composed of a plurality of layers, at least one of the entire layers or the plurality of layers is a layer formed by wet plating. For example, when the layer 5 is composed of a thick Ni plating layer and a small Cr plating layer thereon (Cr is more expensive than Ni and thus has a smaller thickness),
Both the plating layer and the Cr plating layer are formed by wet plating, or the Ni plating layer is formed by wet plating. The reason why wet plating is used is that a plating layer having a large thickness, for example, 15 to 40 μm can be formed easily and in a relatively short time. Plating layer 5
Has a thickness of 15 to 40 μm. The reason is that in order to improve the scratch resistance, a minimum of 15 μm
This is because if the thickness is 40 μm or more, the scratch resistance becomes excessive and the cost is unnecessarily increased.

The method for forming a metal material surface coating structure according to an embodiment of the present invention comprises the steps of forming at least one resin coating layer 3 on a base material of a metal material 1, and forming at least one resin coating layer 3 on the resin coating layer 3. Forming the metal or metal compound layer 5 by wet plating.

The metal material 1 is, for example, an aluminum wheel. The method for forming the layer 3 may be any of electrodeposition coating, electrostatic coating, powder coating, air spray coating, dipping, and the like. In the embodiment of the present invention, a case will be described in which the layer 3 has a plurality of layers, the lower layer is an electrodeposition coating, and the upper layer is a powder coating. In the forming process by electrodeposition coating, first, a metal material 1
Is degreased and washed with water, and is electrodeposited using, for example, an epoxy-based cationic electrodeposition paint. In the electrodeposition coating, an electrodeposition tank filled with a low-concentration aqueous paint (at a temperature of, for example, 27 °
In C), a DC voltage (for example, 210 to 230 V) is applied between the metal material 1 as an electric conductor and the electrode for 2 to 3 minutes, and the fine particles of the paint dispersed in water are applied to the metal material by an electric force. 1 to form a coating film by aggregation and precipitation. The cationic electrodeposition paint is a cathodic deposition paint based on a resin having an onium group such as a basic amino group, ammonium and sulfonium and neutralized with an acid such as a lower organic acid. In the cationic electrodeposition, since the coating is basic, there is no elution of metal ions, which is advantageous for the alkali resistance and corrosion resistance of the coating.
Also, coloring during coating of the coating film is small. The coating thickness is, for example, 10 to 30 μm. After painting, 200 ~
Bake and dry at 210 ° C. for about 10-25 minutes. The coating film thus formed is dense and hard, fills small irregularities of the substrate, has excellent adhesion and adhesion to the substrate, protects the substrate, and improves the corrosion resistance of the substrate.

In the step of forming the powder coating layer on the electrodeposition coating layer, a high DC voltage (30 to 90 kV) is applied between the grounded object (the metal material 1 on which the layer 2 is formed) and the electrode of the gun. ), On the other hand, an acrylic, polyester, or epoxy-based powder paint (having a particle size of about 3 to 6 μm,
(Preheated to about 200 ° C.) from the gun by air force. The powder particles dispersed in the air collide with the ionized air generated by the corona discharge generated at the gun electrode and become charged.They move toward the coating object by the action of the electrostatic field between the gun and the coating object and the air flow, Adsorbs to the surface of the substrate by force. Powder coating is suitable for thick coating and fills relatively large irregularities. The layer 3 is formed to have a thickness of 60 to 150 μm. After painting, bake and dry in a furnace at about 170 ° C. for about 20 to 30 minutes.

Next, the metal or metal compound layer 4 is
At least one layer is formed by plating. When the number of layers 4 is one, the entire layer 4 is formed by wet plating.
When the total number is plural, at least the thickest layer is formed by wet plating. Wet plating includes electroplating or hot dip plating. The plating material is optional,
In the case of a wheel, it is desirable that the outermost layer be chrome-plated from the viewpoint of luster, and that the chrome-plated base be nickel-plated, which has good compatibility with chrome plating and is relatively inexpensive. The total thickness of layer 4 is about 15 to 40 μm, of which the thickness of the chromium plating layer is about 1 to several μm. in this case,
The nickel plating layer must be formed by wet plating, while the chrome plating layer may be formed by wet plating or dry plating (eg, sputtering). In the case of electroplating, plating is performed by immersing a metal material 1 coated with a conductive resin paint 3 on the outermost layer as a cathode in a plating solution and electrolyzing.

[0016]

EXAMPLE An aluminum wheel was selected as the metal material 1, and a film structure was formed on the surface thereof as follows. However, the present invention is not limited to the following. First, the surface of the aluminum wheel was degreased and washed with water. Next, an epoxy diameter cationic electrodeposition paint (trade name: Nippe Power Top PTU)
-600, black system) at a temperature of 27 ° C. for 2-3 mi.
n. Electrodeposited under the condition of 210-230V, thickness about 2
An electrodeposition coating layer of 0 μm was formed. This layer was then baked and dried at a temperature of about 180 ° C. for 18 minutes. Next, a polyester powder coating (Toa Gosei Co., Ltd., Aron Powder P2)
20BK50) with a coating material having conductivity,
Under a voltage condition of kV, a thickness of about 100 μm
m, electrostatic powder coating, baking and drying at a temperature of 170 ° C. × 25 minutes to form a powder coating layer. The electrodeposition coating layer and the powder coating layer constitute the resin coating layer 3.

Next, nickel was formed on the metal material 1 on which the layer 3 was formed by electroplating to a thickness of about 30 μm. The plating solution contains nickel sulfate crystals of 150 to 2 per liter of water.
00g, nickel chloride crystals 15-20g, boric acid 15-
Using a solution mixed with 20 g, nickel was used as the anode, and plating was performed at a temperature of 18 to 30 ° C. and a current density of 0.5 to 1.0 A / dm ² to form a base for chromium plating. Then, chromium plating was formed on the nickel plating by electroplating to a thickness of about 1 μm. The plating solution contains 200 to 250 g of chromic anhydride crystals and 2 to 2 sulfuric acid per liter of water.
Using a solution mixed with 2.5 g, the anode as lead, and a temperature of 45 to 45
Plating was performed at 55 ° C. and a current density of about A / dm ² to form a chromium plating layer. The nickel plating layer and the chrome plating layer constitute a plating layer 5 made of a metal or a metal compound.

The temperature is 39 ° C. × 24 hours, -18 ° C.
A heat endurance test of C × 20 hours and a room temperature of 4 hours was performed for 10 cycles.
It has been found that there is good durability. In addition, it is necessary to make a scratch on the plating layer extending to the resin layer, immerse in an acidic solution of pH 2 for 1 minute, and then immerse in distilled water of pH 7 for 1 minute.
The corrosion resistance test was repeated 00 times, but no chemical erosion was observed on the aluminum base under the resin layer. The wheels provided good corrosion resistance (electric corrosion resistance,
(Corrosion resistance).

[0019]

The following effects can be obtained by both the method of forming the surface coating structure of the metal material according to the first aspect and the method of forming the surface coating structure of the metal material according to the second aspect. Since the resin layer is provided, the surface smoothness of the plating base for plating luster can be obtained, and the cost can be reduced because the buffing step is omitted. Even with respect to corrosion resistance that could not be secured by conventional wet plating, sufficient corrosion resistance can be obtained by covering the material surface with the resin layer. Since the plating thickness can be easily increased by wet plating, the scratch resistance is greatly improved by the hardness of the plating as the surface layer.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a metal material surface coating structure according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal material 2 Primer layer 3 Resin coating layer 4 Primer layer 5 Wet plating layer of metal or metal compound

Claims (2)

[Claims] 1. At least one resin coating layer formed on a base material of a metal material, and at least one metal or metal compound wet plating layer formed on the resin coating layer. Surface coating structure of metal material. 2. A step of forming at least one resin coating layer on a base material of a metal material, and a step of forming at least one metal or metal compound layer on the resin coating layer by wet plating. A method for forming a surface coating structure of a metal material comprising: