KR20090075362A - Method for metal material coating and parts coated by same method - Google Patents

Abstract

A metal painting method and painted components thereby are provided to reduce whole processing cost with a low inferiority rate, and to decrease process time by minimizing the number of processes. A metal painting method includes the following steps of: performing pre-processing on the surface of a metal material of magnesium alloy or aluminum alloy(S11); washing the metal material(S12); and painting the washed metal material(S13). A washing step and a painting step are consecutively performed. A surface pre-processing step includes at least one or more among a degreasing process, an etching process, a desmut process, a mechanical polishing process, and a surface processing process.

Description

Method for metal material coating and parts coated by same method}

TECHNICAL FIELD The present invention relates to a metal coating method and a component coated thereby, and more particularly, to a method for electrodepositing and coating a metallic substrate of a magnesium alloy or an aluminum alloy and a component painted thereby.

Metal substrates based on magnesium or aluminum are lightweight, high strength metal alloy materials, and have excellent recycling properties that can replace plastics used for environmental preservation.

In the case of such an aluminum alloy, after applying the anodizing method, it has been applied to automobiles, aircrafts, mobile devices, home appliances, mobile phones, and mobile devices by providing aesthetics (color) and corrosion resistance mainly by powder coating. However, in the case of aluminum alloys, the process is complicated during anodization and paint adhesion is reduced.

In addition, the practical metal substrate of the magnesium alloy is lighter than aluminum, but corrosion occurs well, and has a lot of difficulties in surface treatment due to corrosion resistance problems.

Accordingly, the present invention is to provide a metal coating method that can reduce the process time and cost.

In addition, the present invention is to provide a metal coating method excellent in the quality of the painted surface.

In addition, the present invention is to provide a component coated by the coating method as described above.

Metal coating method according to an embodiment of the present invention includes the step of pre-treating the surface of the metal substrate of the magnesium alloy or aluminum alloy, the step of washing the metal substrate, and the electrodeposition coating on the washed metal substrate, The washing step and the electrodeposition coating step are performed continuously.

In this case, the surface pretreatment step in the metal coating method includes at least one of a degreasing process, an etching process, a desmerting process, a mechanical polishing process, and a surface adjusting process, and may include washing between the processes.

The method may further include forming a middle or top coat after the electrodeposition coating step in the metal coating method.

Metal coating method according to another embodiment of the present invention comprises the steps of pre-treating the surface of the metal substrate of magnesium alloy or aluminum alloy, forming at least one composite film by the electrochemical method on the surface of the metal substrate, the composite Washing the metal substrate having the film formed thereon, and electrodepositing the washed metal substrate, wherein the washing step and the electrodeposition coating step are performed continuously.

In this case, the current may be supplied in a DC or pulse manner in the composite film forming step in the metal coating method.

In the metal coating method, the surface pretreatment may include at least one of a degreasing process, an etching process, a desmeter process, a mechanical polishing process, and a surface adjustment process, and may include washing between the processes.

In addition, in the metal coating method, the composite film may include at least one of manganese, copper, nickel, zinc, tin, platinum, palladium, lead, gold, and silver.

In addition, after the electrodeposition coating step in the metal coating method may further comprise the step of forming a middle and top coat.

A component according to an embodiment of the present invention includes a metal substrate of magnesium alloy or aluminum alloy, at least one composite film formed by an electrochemical method on the metal substrate, and an electrodeposition coating film on the composite film.

In the metal material, the composite film may include at least one of manganese, copper, nickel, zinc, tin, platinum, palladium, lead, gold, and silver.

In addition, the metal material may further include a middle coating or a top coating on the electrodeposition coating film.

According to the metal coating method according to the present invention, the process time can be shortened by simplifying the number of processes, and the low coating failure rate can reduce the overall process cost, thereby improving efficiency.

Moreover, the metal material excellent in corrosion resistance and coating adhesiveness can be provided by the said coating method.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a metal coating method according to an embodiment of the present invention will be described with reference to FIG. 1. Figure 1 is a flow chart listing the metal coating method according to an embodiment of the present invention in the order of the process.

As shown in FIG. 1, the surface of the metal base material of a magnesium alloy or an aluminum alloy is pretreated (S11).

Surface pretreatment of a metal base material means the process of removing the foreign material of the surface of the metal base material of a magnesium alloy or an aluminum alloy, and improving coating adhesiveness. The surface pretreatment process may include at least one of a degreasing process, an etching process, a desmerting process, a mechanical polishing process, and a surface adjusting process, and may include a washing process between these processes. Water washing in this specification includes ultrasonic water washing.

The degreasing step is a step of removing oil generated in the production process of the metal substrate, and is a process for preventing the formation of an uneven surface treatment film due to oil stains, oil, and other impurities remaining on the surface of the metal substrate. This degreasing process can be performed by immersing the metal substrate in an alkali degreasing agent, and the immersion time varies depending on the geometric shape, size of the metal substrate, and the type of lubricant or other additives used at the time of producing the metal substrate.

An etching process is for removing an oxide film naturally formed on the surface of a metal substrate, and for example, an alkaline etching agent can be used as the etching agent.

The desmut process is intended to remove stains and other by-products of the surface of the metal substrate and to impart more uniform surface properties physically and chemically before proceeding to the subsequent process.

The mechanical polishing process is for peeling off the oxide film layer present on the surface of the metal substrate by a physical method by a mechanical polishing method such as sanding.

The washing step is to clean the surface of the metal substrate cleanly, and is performed using a sufficient amount of deionized water or tap water. The washing process can be carried out, for example, once to three times.

In addition, the ultrasonic washing process, which is a kind of washing process, is intended to completely remove solid impurities such as sand grains or abrasive components that are physically embedded in the surface of the metal substrate.

In more detail, the surface pretreatment may be performed, for example, by a surface pretreatment process on a metal substrate, for example, degreasing → washing water → etching or mechanical polishing → washing water → desmuting. The surface pretreatment is not limited to the above, and various methods may be used depending on the surface state of the metal substrate.

Next, as shown in FIG. 1, the surface-treated metal substrate is washed with water (S12).

As described above, the washing method cleans the surface of the metal substrate using a sufficient amount of pure water or tap water, and the washing includes washing with ultrasonic water.

Next, as shown in FIG. 1, electrodeposited coating is performed on the washed metal substrate (S13).

Electrodeposition should be carried out immediately without any delay or washing of the metal substrate after the washing process. That is, after completion of the washing step, the metal substrate is continuously immersed in the electrodeposition tank to perform electrodeposition coating. The metal substrate may be a cathode or an anode depending on the type of electrodeposition paint applied. The coating material that can be applied to such electrodeposition coating can be both a cationic electrodeposition paint and an anion electrodeposition paint, and is not limited to the resin type (urethane type, acrylic type and melamine modified type or acrylic modified urethane type, etc.) of the electrodeposition paint. In addition, the pH of the solution in the electrodeposition bath is, for example, about 4.0 to 9.0, and the operating temperature is, for example, about 20 to 40 ° C. In addition, the coating is to be cured after electrodeposition, and may be cured by applying heat (hereinafter, referred to as baking), or may be cured through radical reaction by irradiation with ultraviolet rays. The temperature for curing of the paint may vary depending on the characteristics of the electrodeposition paint applied to the metal substrate, for example, in the case of baking, it may be carried out in a temperature range of about 110 to 190 ° C. The electrodeposition coating film formed on the surface of the metal substrate by this electrodeposition process may be formed in various thicknesses, for example, 5 to 100㎛ according to the desired coating film thickness.

Next, as shown in FIG. 1, the intermediate or top coat film is formed on the electrodeposition-coated metal substrate (S14).

In more detail, the formation of the intermediate or top coat film is washed with a sufficient amount of pure water or tap water after the electrodeposition coating, and the surface of the electrodeposition coating in which the electrodeposition paint remains partially is cleaned to minimize the appearance defects after baking. prevent. In addition, the recovery rate of the electrodeposition paint can be increased through the washing process. This washing process is preferably performed once to three times.

After washing with water, the electrodeposited metal substrate is allowed to stand at room temperature in a space free of foreign matter or dust, for example for about 5 to 20 minutes. This operation removes the remaining water on the electrodeposition paint surface. Through this removal process, appearance defects caused by electrodeposition paints remaining in the wash water are partially prevented.

Baking the electrodeposition painted metal substrate dried at room temperature, wherein the baking conditions may vary depending on the electrodeposition paint.

After the electrodeposition coating is finished, the finished metal substrate may be the final product. However, the final product may be made through the baking after applying an intermediate or top coat having excellent adhesion on the electrodeposition coating film. Of course, the coating material applied to the middle or top coat can be applied to any type of water-based, solvent type and small-type and natural drying in the condition that the coating film adhesion with the electrodeposition coating film, which has been previously painted first, is satisfied. In addition, by applying a clear top (top clear) over the middle or top coat, it is also possible to make the final product with a more beautiful appearance through the operation to further increase the surface gloss.

Subsequently, a metal coating method according to another embodiment of the present invention will be described with reference to FIG. 2. Figure 2 is a flow chart listing the metal coating method according to another embodiment of the present invention in the order of the process.

Metal coating method according to another embodiment of the present invention is substantially the same as the metal coating method according to an embodiment of the present invention, except that it further comprises a step of forming a composite film after the surface pretreatment process, A metal coating method according to another embodiment of the present invention will be described based on differences from the metal coating method according to an embodiment.

As shown in Fig. 2, the surface of the metal substrate of the magnesium alloy or the aluminum alloy is pretreated (S11). Since the surface pretreatment is substantially the same as the metal coating method according to an embodiment of the present invention, a detailed description thereof will be omitted.

Next, a composite film is formed on the surface pretreated metal substrate (S22). Under current or acidic solution conditions, for example pH 4 to 13, the metal base is cathode and a constant voltage is applied in a bath equipped with an anode to energize the current simply. The composite film is formed on the surface of the metal substrate by using a method of applying a voltage applied at regular time intervals or intermittently applying a constant time interval (pulse method). By the electrochemical method described above, the metal salt ions in the solution are reduced on the surface of the metal substrate to form a composite film as desired.

At this time, the main component of the solution in the above-mentioned container includes a metal salt, sodium hydroxide, sodium fluoride, a complexing agent (EDTA, cyanide, ammonium salt, phosphate, etc.), a surfactant, the pH of this solution is about 4 to 13, The current density within is about 0.1 to 8 A / dm ² and the electrochemical surface treatment temperature is 20 to 80 ° C.

The composite film formed on the surface of the metal substrate by the electrochemical substitution method as described above, such a composite film is manganese (Mn), copper (Cu), nickel (Ni), zinc (Zn), tin (Sn), platinum (Pt) ), Palladium (Pd), lead (Pb), gold (Au), silver (Ag) and the like as main components, and metal elements or alloys corresponding thereto.

The composite film forming process of the present invention can not only improve corrosion resistance at a relatively low cost than when forming a film by an anodizing method, but also improve adhesion to a coating film formed on the composite film. In addition, by forming a composite film by an electrochemical method using environmentally friendly electrical energy, it is possible to form a film at a relatively low temperature has excellent in terms of process efficiency.

Next, as shown in FIG. 2, the metal substrate on which the composite film is formed is washed with water (S23), and the metal substrate that has been washed with water is subjected to electrodeposition coating immediately without any delay or rest of the process (S24). Subsequently, the intermediate or top coat film is formed on the electrodeposited metal substrate (S25). Since the above water washing, electrodeposition coating, intermediate or top coat film forming process is substantially the same process as the coating method according to an embodiment of the present invention, a detailed description thereof will be omitted.

By forming the electrodeposition coating film on the metal substrate of the aluminum alloy or the magnesium alloy by the above-described metal coating method, it is possible to produce parts having light weight and excellent corrosion resistance at a relatively low cost. Parts according to the present invention can be applied to mobile parts, such as mobile phones, laptops, for example, and also can be applied to car wheels, car bodies or other car parts can bring about the effect of a significant reduction in vehicle fuel economy by light weight In addition, it can be applied to aerospace and aerospace parts.

Hereinafter, the present invention will be described in more detail through experimental examples. However, the following experimental examples are for illustrating the present invention, it should be understood that the present invention is not limited by the following experimental examples.

Experimental Example  One

The aluminum alloy substrate was immersed in an alkali degreaser at a temperature of 80 ° C. for about 5 minutes to remove oil stains, oil and other impurities remaining on the surface. Thereafter, the aluminum alloy substrate was thoroughly cleaned with a sufficient amount of pure water to remove degreaser residual components. Subsequently, in order to remove the oxide film naturally formed in the surface of the aluminum alloy base material, it etched using the alkaline etching agent. Subsequently, the entire surface of the aluminum alloy substrate after the etching step was cleanly washed with a sufficient amount of pure water to remove the etchant component. Thereafter, smuts and other by-products formed in the etching process were removed from the surface of the aluminum alloy substrate, and a desmut process was performed to impart more uniform surface properties physically and chemically.

Next, the entire surface of the aluminum alloy substrate was washed clean with a sufficient amount of pure water to prevent the dispersant solution component from being incorporated into the electrodeposition tank of the electrodeposition coating process described later.

Subsequently, electrodeposition coating was continuously performed on the aluminum alloy substrate having been washed with water as described above without stopping. An aluminum alloy base material is immersed in an electrodeposition tank, and electrodeposition coating is performed. At this time, the electrodeposition paint was a cationic electrodeposition paint, the pH of the solution was about 6, the voltage was about 100V, and the implementation temperature was about 28 ° C. The thickness of the electrodeposition coating film was formed to about 16 micrometers.

Next, the electrodeposited aluminum alloy substrate was washed with a sufficient amount of pure water to wash the entire wet film surface in which a part of the electrodeposition paint remained. Thereafter, the aluminum alloy substrate on which the electrodeposition coating film is formed is left at room temperature for about 10 minutes in a space free of foreign matter or dust to remove the flushing water remaining on the surface of the electrodeposition coating film, followed by baking at about 165 캜 for 20 minutes. Was carried out. After forming the intermediate and top coats on the roughened magnesium alloy substrate, the specimen was prepared through the baked.

Experimental Example  2

The specimen was prepared in substantially the same manner as in Example 1 except that the voltage at the time of electrodeposition coating was about 150V and the thickness of the electrodeposition coating film was formed at about 22 μm.

Experimental Example  3

The specimen was prepared in substantially the same manner as in Example 1 except that the voltage at the time of electrodeposition coating was about 200V and the thickness of the electrodeposition coating film was formed at about 28 μm.

Experimental Example  4

The specimen was prepared in substantially the same manner as in Example 1 except that the voltage at the time of electrodeposition coating was about 250V and the thickness of the electrodeposition coating film was formed at about 33 μm.

Salt spray salt spray ) Test

The specimens of Experimental Examples 1 to 4 were subjected to a salt spray test in accordance with ASTM B 117 conditions. The specimens of Experimental Examples 1 to 4 did not generate any white rust even after 720 hours under the salt spray test as described above.

It was found from the salt spray test that the specimens of Experimental Examples 1 to 4 according to the present invention had excellent corrosion resistance.

Experimental Example  5

The magnesium alloy substrate is immersed in an alkaline degreaser for about 5 minutes at a temperature of 80 ° C. to remove oil stains, oil and other impurities remaining on the surface. Thereafter, the magnesium alloy substrate is washed with a sufficient amount of pure water to clean the entire surface to remove degreaser residual components. Subsequently, in order to remove the oxide film which was formed residually on the surface of a magnesium alloy base material, it etched using the alkaline etching agent. Subsequently, the entire surface of the magnesium alloy substrate after the etching process was washed with a sufficient amount of pure water to remove the etchant component. The stains and other by-products formed in the etching process were then removed from the magnesium alloy substrate surface and surface adjustments were made to give more uniform surface properties physically and chemically.

After the surface adjustment is completed, a composite film is formed on the surface of the magnesium alloy substrate by an electrochemical method using a magnesium alloy substrate as a cathode and an insoluble anode as an anode in a solution mainly containing manganese in the container. At this time, the solution had a pH of about 11, a current density of about 3A / dm ² , and an implementation temperature of about 50 ° C. The main components of the composite film formed by the electrochemical method as described above were manganese and phosphoric acid, and the thickness thereof was about 2 m.

Next, the magnesium alloy substrate was washed with a sufficient amount of pure water to clean the entire surface, thereby preventing the solution component of the composite coating process from being incorporated into the electrodeposition tank of the electrodeposition coating process described later.

Subsequently, electrodeposition coating was continuously performed on the magnesium alloy substrate having been washed with water as described above without stopping. A magnesium alloy base material is immersed in an electrodeposition tank, and electrodeposition coating is performed. At this time, the electrodeposition paint was a cationic electrodeposition paint, the pH of the solution was about 6, the voltage was about 150V, and the implementation temperature was about 28 ° C. The thickness of the electrodeposition coating film was formed to about 22 micrometers.

Next, the magnesium alloy base material after electrodeposition coating was washed with a sufficient amount of pure water to wash the entire wet film surface in which part of the electrodeposition paint remained. Thereafter, the magnesium alloy substrate on which the electrodeposition coating film is formed is left to stand at room temperature for about 10 minutes in a space free of substance or dust, and the water washing water remaining on the surface of the electrodeposition coating film is removed, followed by baking at about 165 ° C. for 20 minutes. Was carried out. After forming the intermediate and top coats on the roughened magnesium alloy substrate, the specimen was prepared through the baked.

Experimental Example  6

The specimen was prepared in substantially the same manner as in Example 1 except that the voltage at the time of electrodeposition coating was 250V and the thickness of the electrodeposition coating film was formed at about 33 μm.

Coating Adhesion  Test

Based on the DIN 53151 test standard, 100 square shapes were cut at intervals of 1 mm in width and length by using a cutting machine having sharp edges on specimen surfaces of Experimental Examples 5 and 6. The strength of the adhesiveness was evaluated by the number of pieces remaining in 100 square coating films after the surface of the cut specimen was attached with tape and pulled up with force. The coating film adhesion test results of Experimental Examples 5 and 6 are shown in FIGS. 3 and 4. 3 and 4 are photographs showing the adhesion test results of Experimental Examples 5 and 6, respectively.

The coating film adhesion test showed that the coating film adhesion of the specimens of Examples 5 and 6 according to the present invention was excellent.

Coating Film Hardness Test

Sharpen the pencil of KS G2603 above the ordinary grade so that the core is exposed to about 3mm, and then grind it in a circle at right angles to 400 or more abrasive papers placed on a solid plane. Make the angle of the plane as sharp as possible (90 °). While holding such a pencil about 45 ° with respect to the horizontal plane of the specimens of Experimental Example 1 to 6, a line was repeatedly drawn in a straight line while applying a load of about 10 N (1 kg). The length of this line is 20 mm or more and 3 lines or more. In this way, the test was performed with a pencil having high hardness (H <2H <3H <4H <5H <6H) until the sharp part of the pencil lead did not show a trace on the coating surface to be tested.

As a result of the said coating film pencil hardness test, Experimental Examples 1-6 showed the hardness of 2H or more and 3H or less. From this, it was found that the specimens of Experimental Examples 1 to 6 according to the present invention had excellent hardness.

In the above described exemplary embodiments of the present invention by way of example, the scope of the present invention is not limited to the specific embodiments as described above, the patent of the present invention by those skilled in the art to which the present invention belongs Changes may be made as appropriate within the scope of the claims.

Figure 1 is a flow chart listing the metal coating method according to an embodiment of the present invention in the order of the process.

Figure 2 is a flow chart listing the metal coating method according to another embodiment of the present invention in the order of the process.

3 and 4 are photographs showing the adhesion test results of Experimental Examples 5 and 6, respectively.

Claims (11)

Pretreating the surface of the metal substrate of magnesium alloy or aluminum alloy; Washing the metal substrate; And Electrodeposition coating on the washed metal substrate, The washing step and the electrodeposition coating step is a metal coating method is performed continuously. The method of claim 1, The surface pretreatment step includes at least one of a degreasing process, an etching process, a desmerting process, a mechanical polishing process, and a surface adjusting process, and washing with water between the processes. The method of claim 1, Metal coating method further comprises the step of forming the intermediate or top coat after the electrodeposition coating step. Pretreating the surface of the metal substrate mainly composed of magnesium alloy or aluminum alloy; Forming at least one composite film by an electrochemical reaction on the surface of the metal substrate; Washing the metal substrate on which the composite film is formed; And Electrodepositing the washed metal substrate; The washing step and the electrodeposition coating step is a metal coating method is performed continuously. The method of claim 4, wherein Metal coating method in which the current is supplied in a direct current or a pulse method in the composite film forming step. The method of claim 4, wherein The surface pretreatment step includes at least one of a degreasing process, an etching process, a desmerting process, a mechanical polishing process, and a surface adjusting process, and washing with water between the processes. The method of claim 4, wherein The composite film is a metal coating method comprising at least one of manganese, copper, zinc, tin, platinum, palladium, lead, gold and silver. The method of claim 4, wherein Metal coating method further comprises the step of forming the intermediate or top coat after the electrodeposition coating step. Metal base materials based on magnesium alloys or aluminum alloys; At least one composite film formed by an electrochemical method on the metal substrate; And A component comprising an electrodeposition paint film on the composite film. The method of claim 9, The composite coating comprises at least one of manganese, copper, nickel, zinc, tin, platinum, lead, gold and silver. The method of claim 9, And a middle coat or a top coat on the electrodeposition coating film.

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