Coated metal member and method for manufacturing the same

Abstract

To provide a coated metal member having an excellent corrosion inhibition effect capable of inhibiting the progress of corrosion under a coating film and having excellent aesthetics in appearance, and a method for producing the same.SOLUTION: A coated metal member 1 comprises a metal member 30 and an electrodeposited coating film 10 coating a surface of the metal member. The electrodeposited coating film 10 contains microcapsules 20 containing a corrosion inhibitor, and the microcapsules 20 in the electrodeposited coating film are unevenly distributed on the metal member 30 side in the thickness direction of the coated metal member 1. The electrodeposited coating film 10 can be obtained by immersing the metal member 30 in an electrolytic solution, electrodepositing the anion-type microcapsules 20 on the surface of the metal member by energizing the metal member as an anode and then electrodepositing a cation electrodeposited coating on the surface of the metal member by energizing the metal member as a cathode to form a coating film, which is then baked and cured.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coated metal member and a method for manufacturing the same.

Background Art

[0002] In order to protect the surface of a metal member such as a steel plate of an automobile, the surface of the metal member is covered with a coating film. However, as shown in FIG. 12(a), due to flying stones or the like during driving, the coating film 80 may be broken or damaged 80B, and a part of the steel plate 30 may be exposed. Then, as shown in FIG. 12(b), the under-film corrosion 31 proceeds along the interface between the coating film 80 and the steel plate 30, and the corrosion product or the generated gas (H2 etc.) 32 lifts the coating film 80, generating a swelling of the coating film in a hemispherical or filamentous shape, which deteriorates the appearance quality of the automobile.

[0003] As a technique for suppressing such under-film corrosion, a coating containing microcapsules encapsulating a corrosion inhibitor in the coating film has been proposed. For example, Patent Document 1 describes a resin-coated metal plate provided with a resin film obtained from a resin composition on at least one side of a metal plate, wherein the resin composition contains a water-soluble acidic resin having a number average molecular weight of 1,000 to 100,000 and microcapsules in which a polyphenol compound is encapsulated in porous fine particles having an average particle size of 5 μm or less, and the resin-coated metal plate is excellent in corrosion resistance and surface properties.

[0004] Also, various techniques have been proposed for the microcapsules themselves having inclusions. For example, Patent Document 2 describes a water-dispersible powder microcapsule obtained by coating powder particles as a core with an aqueous resin layer having a charge necessary for water dispersion, and a crosslinked layer of a water-insoluble thermosetting crosslinking agent that is self-crosslinked and / or crosslinked with the aqueous resin is interposed between the powder particles and the aqueous resin layer.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-237460 [Patent Document 2] Japanese Patent Application Publication No. 171637 / 1983 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the technology described in Patent Document 1, for example, as shown in Figure 13, when a fracture or scratch 80B occurs in the coating 80 on the surface of the steel plate 30, the outer shell of the microcapsule 81 in the coating 80 at the fractured or scratched portion is destroyed, and the corrosion inhibitor contained within is released. A wide variety of corrosion inhibitors are used, but many of them have the effect of forming a protective film 81S on the exposed surface of the steel plate 30.

[0007] However, while the corrosion inhibitor is effective immediately after cracks or scratches 80B occur in the coating 80, as the protective film 81S gradually loses its effectiveness and subcoating corrosion 31 occurs, as shown in Figure 14, there are only a few microcapsules 81 near the surface of the steel plate 30, so there is almost no outflow of the corrosion inhibitor, and therefore, subcoating corrosion 31 progresses.

[0008] Since the microcapsules that are destroyed in this way are limited to the vicinity of the rupture or damage to the coating, increasing the microcapsule content may be considered to obtain a sufficient corrosion inhibitory effect. However, increasing the microcapsule content in this way may not only increase costs but also lead to problems such as unevenness on the surface of the coating caused by the microcapsules, which degrades the appearance quality.

[0009] Furthermore, while spray painting can be used as a method for applying paint containing microcapsules, unlike electrodeposition coating, it is difficult to obtain a uniform coating in areas that cannot be directly sprayed, such as bag structures, with spray painting. In addition, spray painting has the problem of lower adhesion between the coating and the steel plate compared to electrodeposition coating, making it easier for corrosion to progress beneath the coating.

[0010] Electrodeposition coating generally involves connecting the object to be coated (steel plate) to an external power source and immersing it in an electrodeposition solution containing either a positively charged aqueous resin (cationic electrodeposition paint) or a negatively charged aqueous resin (anionic electrodeposition paint). By setting the potential of the steel plate to either the negative electrode (cationic electrodeposition) or the positive electrode (anionic electrodeposition), the electrodeposition paint is adsorbed onto the steel plate by electrophoresis, forming a coating film. In this method, in order to adsorb microcapsules onto the surface of the steel plate, cationic microcapsules must be used for cationic electrodeposition, and anionic microcapsules for anionic electrodeposition. Patent document 2 describes charged microcapsules, but it does not describe electrodeposition coating using these microcapsules.

[0011] When electrodeposition coating is performed using microcapsules, as shown in Figure 15, an electrodeposition solution 75 containing electrodeposition paint 73 and microcapsules 81 is prepared in a polar solvent 74 such as water, and the steel plate 30 is connected to an external power supply 76 and immersed in this electrodeposition solution 75. When power is applied, the microcapsules 81 are significantly larger in size than the electrodeposition paint 73, resulting in greater resistance from the electrodeposition solution 75, and their electrophoretic movement speed is slower than that of the electrodeposition paint 73. As a result, the microcapsules 81 reach the surface of the steel plate 30 later than the electrodeposition paint 73, and the resulting coating film 80, as shown in Figure 16, has fewer microcapsules 81 near the interface with the steel plate 30, and more microcapsules 81 on the opposite, visible surface side.

[0012] As described above, if there are few microcapsules 81 in the coating 80 near the interface with the steel plate 30, only a small number of microcapsules will be destroyed when subcoating corrosion occurs, and the effect of suppressing the progression of subcoating corrosion will be minimal. Furthermore, because there are many microcapsules 81 on the surface side of the coating 80, irregularities are more likely to occur on the surface, resulting in defects that impair the aesthetic appearance of the paint.

[0013] Therefore, in view of the above problems, the present invention aims to provide a coated metal member and a method for manufacturing the same that have an excellent corrosion suppression effect that can suppress the progression of corrosion under the coating, and also have an excellent aesthetic appearance. [Means for solving the problem]

[0014] To achieve the above objective, the present invention, in one aspect thereof, provides a coated metal member comprising a metal member and an electrodeposited coating film covering the surface of the metal member, wherein the electrodeposited coating film contains microcapsules containing a corrosion inhibitor, and the microcapsules within the electrodeposited coating film are unevenly distributed towards the metal member in the thickness direction of the coated metal member.

[0015] In another aspect, the present invention provides a method for manufacturing a coated metal member comprising a metal member and an electrodeposited coating film covering the surface of the metal member, comprising: a step of preparing an electrolyte by mixing a polar solvent with negatively charged anionic microcapsules containing a corrosion inhibitor and a cationic electrodeposited paint; a first electrodeposition coating step of immersing the metal member in the electrolyte introduced into an electrolytic cell and applying an electric current with the metal member as the anode to electrodeposit the anionic microcapsules onto the surface of the metal member; a second electrodeposition coating step of applying an electric current with the metal member as the cathode in the electrolytic cell to electrodeposit the cationic electrodeposited paint onto the surface of the metal member; and a step of baking and curing the cationic electrodeposited paint electrodeposited onto the surface of the metal member to form an electrodeposited coating film.

[0016] The manufacturing method of a coated metal member including a metal member according to the present invention and an electrodeposition coating film covering the surface of the metal member, in another aspect, includes a step of preparing an electrolytic solution by mixing a cationic microcapsule having a negative charge containing a corrosion inhibitor and an anion electrodeposition paint in a polar solvent, and dipping a metal member into the electrolytic solution introduced into an electrolytic cell, and shadow energizing as a cathode to electrodeposit the cationic microcapsule on the surface of the metal member in a first electrodeposition coating step, and in the electrolytic cell, Yang energizing as an anode to electrodeposit the anion electrodeposition paint on the surface of the metal member in a second electrodeposition coating step, and a step of baking and curing the anion electrodeposition paint electrodeposited on the surface of the metal member to form an electrodeposition coating film.

Advantages of the Invention

[0017] Thus, according to the present invention, since the microcapsules in the electrodeposition coating film are unevenly distributed on the metal member side in the plate thickness direction of the coated metal member, it has an excellent corrosion inhibition effect capable of suppressing the progress of underfilm corrosion, and also has excellent aesthetics on the appearance surface.

Brief Description of the Drawings

[0018] [Figure 1] It is a cross-sectional view schematically showing an embodiment of a coated metal member according to the present invention. [Figure 2] It is a cross-sectional view schematically showing the corrosion inhibition effect of the coated metal member shown in FIG. 1. [Figure 3] It is a schematic diagram for explaining a crosslinking agent coating step in a microcapsule manufacturing step by a liquid-phase curing coating method in an embodiment of the manufacturing method of a coated metal member according to the present invention. [Figure 4] It is a schematic diagram for explaining a crosslinking agent curing step in a microcapsule manufacturing step by a liquid-phase curing coating method. [Figure 5] It is a schematic diagram for explaining a centrifugation step in a microcapsule manufacturing step by a liquid-phase curing coating method. [Figure 6]In one embodiment of the method for manufacturing a coated metal member according to the present invention, it is a schematic diagram for explaining a microcapsule manufacturing step by the polyaniline method. [Figure 7] It is a schematic diagram for explaining the (a) non-conductive state before doping, (b) state after doping with an acid, and (c) conductive state after completion of doping of a polyaniline-based polymer in the polyaniline method. [Figure 8] In one embodiment of the method for manufacturing a coated metal member according to the present invention, it is a schematic diagram for explaining an electrodeposition solution preparation step. [Figure 9] In one embodiment of the method for manufacturing a coated metal member according to the present invention, it is a schematic diagram for explaining an initial state of an electrodeposition coating step. [Figure 10] In one embodiment of the method for manufacturing a coated metal member according to the present invention, it is a schematic diagram for explaining a first electrodeposition coating step. [Figure 11] In one embodiment of the method for manufacturing a coated metal member according to the present invention, it is a schematic diagram for explaining a second electrodeposition coating step. [Figure 12] It is a cross-sectional view schematically showing an example of a conventional coated metal member. [Figure 13] It is a cross-sectional view schematically showing another example of a conventional coated metal member. [Figure 14] It is a cross-sectional view schematically showing the corrosion inhibition effect of the conventional coated metal member shown in FIG. 13. [Figure 15] It is a schematic diagram for explaining problems that occur when performing electrodeposition coating using microcapsules. [Figure 16] It is a cross-sectional view schematically showing the coated metal member obtained by the electrodeposition coating of FIG. 15.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an embodiment of a coated metal member and a method for manufacturing the same according to the present invention will be described with reference to the accompanying drawings. Note that the drawings are illustrated so that the configuration is simple and clear, and are not necessarily drawn to scale.

[0020] As shown in Figure 1, the coated metal member 1 of this embodiment comprises a metal member 30 and an electrodeposited coating film 10 that covers the surface of the metal member 30. The electrodeposited coating film 10 contains microcapsules 20 containing a corrosion inhibitor, and these microcapsules 20 are unevenly distributed within the electrodeposited coating film 10 towards the metal member 30 in the thickness direction of the coated metal member 1. Each component will be described in detail below.

[0021] The electrodeposited coating film 10 is a coating obtained by electrodeposition coating, and either cationic electrodeposition paint or anionic electrodeposition paint can be used as the electrodeposition coating. The anionic electrodeposition paint is not particularly limited as long as it is a thermosetting aqueous resin that has a negative charge in water and is conductive, but for example, polybutadiene resin-based paints, acrylic resin-based paints, polyurethane resin-based paints, etc. can be used. The cationic electrodeposition paint is not particularly limited as long as it is a thermosetting aqueous resin that has a positive charge in water and is conductive, but for example, polyamide-epoxy resin-based paints, acrylic resin-based paints, polyurethane resin-based paints, etc. can be used. Therefore, the parts of the electrodeposited coating film 10 other than the microcapsules 20 are composed of electrodeposited resin 11 which is formed by curing the electrodeposited paint.

[0022] The microcapsules 20 contain either a powdered corrosion inhibitor or a powder impregnated with a liquid corrosion inhibitor. The corrosion inhibitor is not particularly limited as long as it is released from the microcapsules 20 to form a protective film 20S when the microcapsules 20 are ruptured, as shown in Figure 2. For example, if it is in powder form, carboxylates, molybdates, chromates, titanium dioxide, tannins, kaolinite, etc. can be used, and if it is in liquid form, organic nitrogen compounds (such as butylamine), organic oxygen compounds (such as polyoxyethylene nonyl ether), organic sulfur compounds (such as ethyl mercaptan), etc. can be used.

[0023] The outer shell of the microcapsule 20 enclosing the corrosion inhibitor is not particularly limited as long as it can have a positive or negative charge and, as shown in Figure 2, can be destroyed when rupture or damage 10B occurs in the electrodeposited coating 10, thereby releasing the contained corrosion inhibitor. For example, polybutadiene resins and polyurethane resins can be used. As will be described in more detail later, a two-layer structure is preferable. For example, the inner layer of the outer shell may be a cross-linked layer formed by curing a cross-linking agent, and the outer layer may be an electrodeposited coating layer. In this case, if the electrodeposited coating 10 is a cationic electrodeposited coating, the electrodeposited coating layer is preferably an anionic electrodeposited coating, and if the electrodeposited coating 10 is an anionic electrodeposited coating, the electrodeposited coating layer is preferably a cationic electrodeposited coating. Alternatively, the inner layer of the outer shell may be a polyaniline polymer layer, and the outer layer may be an anionic layer of sulfuric acid or an organic acid having a cyclic structure.

[0024] The size of the microcapsules 20 is preferably in the range of 0.1 to 10 μm, and more preferably in the range of 1 to 3 μm.

[0025] The microcapsules 20 are preferably located within the electrodeposited coating 10 at a position in contact with the interface with the metal member 30, and are particularly preferably attached to or fused to the metal member 30. Because the microcapsules 20 are attached to or fused to the metal member 30 in this way, as shown in Figure 2, if fractures or scratches 10B occur in the electrodeposited coating 10, and sub-coating corrosion 31 occurs on the metal member 30, the microcapsules 20 are reliably destroyed by the progression of the sub-coating corrosion 31, and the encapsulated corrosion inhibitor continues to leak out sequentially. Therefore, a protective film 20S is formed on the surface of the steel plate 30 exposed by the sub-coating corrosion 31, and the corrosion inhibitory effect can be continuously exerted. Even if the microcapsules 20 are not attached to or fused to the metal member 30, the progression of sub-coating corrosion 31 will cause fractures in the portion of the electrodeposited coating 10 near the metal member 30, destroying the microcapsules 20 in that portion, allowing the encapsulated corrosion inhibitor to continuously leak out and form a protective film 20S.

[0026] The metal component 30 is not particularly limited as long as it can be electrodeposited, and for example, steel plates, aluminum plates, magnesium plates, etc. can be used. The metal component 30 may also be surface-treated as long as it can be electrodeposited.

[0027] Next, the manufacturing method for the coated metal member of this embodiment will be described. This manufacturing method includes a microcapsule manufacturing step, an electrodeposition solution manufacturing step, an electrodeposition coating step, and a baking step. The electrodeposition coating step is divided into a first electrodeposition coating step and a second electrodeposition coating step. These steps will be described in detail below.

[0028] [1. Microcapsule Manufacturing Process] The microcapsule fabrication process is not particularly limited as long as it is a manufacturing method that can produce microcapsules that have an electric charge on their outer shell and can undergo electrophoresis in an electrolyte solution. For example, they can be fabricated by the liquid curing coating method or the polyaniline method described later.

[0029] [1A. Liquid-curing coating method] The liquid curing coating method allows for the encapsulation of microcapsules with powdered corrosion inhibitors or powders impregnated with liquid corrosion inhibitors. In the liquid curing coating method, the microcapsule fabrication process includes three sub-steps: a crosslinking agent coating step, a crosslinking agent curing step, and a centrifugation step.

[0030] First, in the crosslinking agent coating process, as shown in Figure 3, a powdered corrosion inhibitor, or a powder 21P impregnated with a liquid corrosion inhibitor (hereinafter simply referred to as "corrosion inhibitor"), is added to the main body 41 of a funnel-shaped container 40 filled with liquid crosslinking agent 22L. Examples of powders used for impregnation with the corrosion inhibitor include talc, calcium carbonate, barium carbonate, silica, and carbon. The crosslinking agent 22L is not particularly limited as long as it is a water-insoluble resin that hardens at 60-100°C; for example, melamine resin can be used.

[0031] Then, by pressurizing the crosslinking agent 22L and the corrosion inhibitor 21P through the opening of the main body 41 using a pressurizer 43 and pushing them out through the microchannel 42 of the funnel-shaped container 40, particles 20A in which the corrosion inhibitor 21P is coated with the crosslinking agent 22L can be obtained. In addition to the method shown in Figure 3, particles in which the corrosion inhibitor is coated with the crosslinking agent can also be obtained by methods disclosed in, for example, Japanese Patent Application Publication No. 2013-71080 and Japanese Patent Application Publication No. 2013-81929.

[0032] Next, in the crosslinking agent curing process, as shown in Figure 4(a), a slurry 24 containing a sufficient amount of anionic electrodeposition paint 23N in 24L of a polar solvent such as water is filled into a stirring tank 50, and the corrosion inhibitor particles 20A coated with the crosslinking agent are added to this stirring tank 50. As the anionic electrodeposition paint 23N, a resin-based electrodeposition paint similar to the anionic electrodeposition paint used for the electrodeposition coating film 10 described above can be used.

[0033] Then, the mixture is heated to 60-100°C while being stirred with a stirrer 52. As a result, as shown in Figure 4(b), the crosslinking agent 22L hardens with the anionic electrodeposition paint 23N attached, forming an anionic microcapsule 20 with a two-layer outer shell (i.e., an electrodeposition paint layer 23 on the outside and a crosslinked layer 22 with the hardened crosslinking agent on the inside). The electrodeposition paint layer 23 and the crosslinked layer 22, and the corrosion inhibitor 21 and the crosslinked layer 22, are both chemically crosslinked on their surfaces and strongly bonded together. As shown in Figure 4, when anionic electrodeposition paint 23N is used, anionic microcapsules 20 are formed, while when cationic electrodeposition paint is used instead of anionic electrodeposition paint 23N, cationic microcapsules are formed. As the cationic electrodeposition paint, a resin-based electrodeposition paint similar to the cationic electrodeposition paint used for the electrodeposition coating film 10 described above can be used.

[0034] The anionic microcapsules 20 obtained in this way are cooled to below 60°C in a slurry containing unreacted anionic electrodeposition paint 23N, and then introduced into a centrifuge 60 as shown in Figure 5. In the centrifugation step, the slurry is centrifuged to extract slurry 61 containing a large amount of microcapsules 20, which have a higher specific gravity than the anionic electrodeposition paint 23N. The remaining slurry 62, which contains a large amount of anionic electrodeposition paint 23N, can be returned to the stirring tank 50 in the crosslinking agent curing step and reused.

[0035] [1B. Polyaniline method] The polyaniline method allows for the encapsulation of liquid corrosion inhibitors or liquids (e.g., aqueous solutions, organic solvents, inorganic solvents) in which solid corrosion inhibitors are dissolved or dispersed. The polyaniline method is described in Japanese Patent Publication No. 2021-530610, and its outline is as follows: After creating microcapsules 20B having an outer shell of a polyaniline polymer 25 containing a corrosion inhibitor 21 (Figure 6(a)), the surface of this outer shell is doped with an acid (such as sulfuric acid or benzenesulfonic acid) to form negatively charged anion layers 26 and 27 on the outside of the polyaniline polymer 25 (Figure 6(b) or (c)). This will be explained in more detail below.

[0036] Polyaniline polymers, as shown in Figure 7(a), are single-chain polymers containing benzene rings and quinonoid rings, with amide structures connecting the benzene rings and imide structures connecting the benzene rings and quinonoid rings. As shown in Figure 7(b), when an aqueous solution containing this polyaniline polymer is doped with an arbitrary acid (in Figure 7(b), sulfuric acid is used as an example), H atoms are attached to the pair of lone pairs of electrons in the outermost shell of the nitrogen atom in the imide structure. +Ions are attracted, leading to the formation of covalent bonds. This triggers the completion of doping, and as shown in Figure 7(c), the imide structure and quinonoid ring transform into the more stable amide structure and benzene ring, respectively. This transformation causes the polyaniline polymer to change from a non-conductive state to a conductive state (a state in which positive charges can move within the polyaniline polymer 25).

[0037] This H + The amide structure, which is formed by doping with ions and changing from an imide structure, has a positive charge, so it is compatible with the anion of an acid (for example, HSO4 when sulfuric acid is used). - Ionic bonds are formed with the ions, and as shown in Figure 6(b), a negatively charged anion layer 26 is formed on the outside of the outer shell of the microcapsule 20. Since the inner polyaniline polymer 25 has a positive charge, the overall charge of the microcapsule 20 becomes 0. However, if the electrodes are close enough, the negative charge on the outside of the outer shell causes electrophoresis, resulting in an anionic microcapsule 20 that can be applied to electrodeposition coating.

[0038] Any acid can be used for doping, but using organic acids with a cyclic structure such as benzenesulfonic acid, camphorsulfonic acid, or polystyrenesulfonic acid results in a thicker anion layer 27, as shown in Figure 6(c). This reduces the influence of the positive charge of the inner polyaniline polymer 25, making it possible to create an anionic microcapsule 20 that is more easily electrophoresed than when using inorganic acids such as sulfuric acid.

[0039] [2. Electrodeposition Solution Preparation Process] The electrodeposition solution preparation process involves mixing a slurry 71 containing anionic microcapsules 20 prepared by methods such as liquid curing coating or polyaniline method with a solution 72 containing cationic electrodeposition paint 73 to obtain an electrolyte 75 containing anionic microcapsules 20 and cationic electrodeposition paint 73. Polar solvents such as water can be used as solvents for the slurry 17 and solution 72; therefore, the solvent for the electrolyte 75 can be a polar solvent such as water. If cationic microcapsules are prepared in the microcapsule preparation process, they are mixed with the anionic electrodeposition paint to prepare the electrodeposition solution.

[0040] [3. Electrodeposition Coating Process] In the electrodeposition coating process, first, as shown in Figure 9, the metal member 30 to be coated is connected to an external power supply 76 and immersed in the electrodeposition solution 75. Then, by performing the first electrodeposition coating process and the second electrodeposition coating process in sequence, electrodeposition coating can be performed so that the anionic microcapsules 20 are unevenly distributed on the metal member 30 side.

[0041] In the first electrodeposition coating process, as shown in Figure 10, the potential of the metal member 30 is set to anode by an external power supply 76, and anionic microcapsules 20 are adsorbed onto the surface of the metal member 30 by electrophoresis. Immediately after adsorption, current is passed from the metal member 30 to the outer shell of the anionic microcapsule 20 as indicated by arrow 77, generating Joule heat. As a result, a portion of the outer shell fuses to the surface of the metal member 30, and the anionic microcapsule 20 loses its charge. In the first electrodeposition coating process, the cationic electrodeposition paint 73 undergoes electrophoresis in the direction away from the metal member 30, which is the anode, and therefore does not hinder the adsorption and fusion of the anionic microcapsules 20.

[0042] Next, in the second electrodeposition coating process, as shown in Figure 11, the potential of the metal member 30 is set to cathode by an external power supply 76, and the cationic electrodeposition paint 73 is adsorbed onto the surface of the metal member 30, thereby forming a coating film containing anionic microcapsules 20. In the second electrodeposition coating process, the anionic microcapsules 20 undergo electrophoresis in the direction away from the metal member 30 which is acting as the cathode. Therefore, anionic microcapsules 20 that were not adsorbed or fused to the metal member 30 in the first electrodeposition coating process are hardly incorporated into the coating film formed by the cationic electrodeposition paint 73.

[0043] While the electrodeposition coating process for anionic microcapsules 20 has been described, in the case of cationic microcapsules, in the first electrodeposition coating process, the potential of the metal member is set to cathode, allowing the cationic microcapsules to be adsorbed onto the surface of the metal member by electrophoresis and then fused. Then, in the second electrodeposition coating process, the potential of the metal member is set to anode, allowing the anionic electrodeposition paint to be adsorbed onto the surface of the metal member, thereby forming a coating film containing cationic microcapsules. Thus, electrodeposition coating can be performed in which the microcapsules are predominantly located on the metal member side, similar to the case of anionic microcapsules.

[0044] [4. Baking Process] Then, by heating the electrodeposited coating film, in which the resulting microcapsules are predominantly located on the metal member side, to the temperature at which the electrodeposited paint hardens, the painted surface of the metal member, the outer shell of the microcapsules, and the electrodeposited paint fuse together, resulting in a strong electrodeposited coating film. Thus, an electrodeposited coating film 10 can be obtained in which the microcapsules 20 shown in Figure 1 are predominantly located on the metal member 30 side, with a particularly large number of them adhering to the metal member 30. [Explanation of Symbols]

[0045] 1. Covered metal member 10 Electrodeposition coating 20 Microcapsules (Anionic Microcapsules) 20S protective film 21 Corrosion inhibitors 22 Crosslinked layer 23 Electrodeposition paint layer 25 Polyaniline polymers 26, 27 Anion layer 30 Metal components (steel plates) 31 Corrosion under paint film 40 Funnel shaped container 50 Agitation tank 60 Centrifugal Separators 73 Cationic electrodeposition paint 75 Electrodeposition liquid 80 Coating film 81 microcapsules 81 Protective film

Claims

1. A coated metal member comprising a metal member and an electrodeposited coating film covering the surface of the metal member, A coated metal member wherein the electrodeposited coating contains microcapsules containing a corrosion inhibitor, and the microcapsules within the electrodeposited coating are unevenly distributed towards the metal member in the thickness direction of the coated metal member.

2. The coated metal member according to claim 1, including one in which the microcapsules in the electrodeposited coating film are attached to the surface of the metal member.

3. The coated metal member according to claim 1 or 2, wherein the surface of the microcapsule is coated with an anionic electrodeposition coating, and the electrodeposition coating film is a cationic electrodeposition coating.

4. The coated metal member according to claim 1 or 2, wherein the surface of the microcapsule is coated with a cationic electrodeposition coating, and the electrodeposition coating film is an anionic electrodeposition coating.

5. A method for manufacturing a coated metal member comprising a metal member and an electrodeposited coating film covering the surface of the metal member, A process of preparing an electrolyte by mixing a polar solvent with negatively charged anionic microcapsules containing a corrosion inhibitor and a cationic electrodeposition coating, A first electrodeposition coating step involves immersing a metal member in the electrolyte introduced into an electrolytic cell, and applying an electric current with the metal member as the anode to electrodeposit the anionic microcapsules onto the surface of the metal member. A second electrodeposition coating step is performed in which the metal member is used as the cathode in the electrolytic cell and current is passed through it to electrodeposit the cationic electrodeposition paint onto the surface of the metal member, The process involves baking and curing the cationic electrodeposition paint that has been electrodeposited onto the surface of the metal member to form an electrodeposited coating film. A manufacturing method that includes [details omitted].

6. A method for manufacturing a coated metal member comprising a metal member and an electrodeposited coating film covering the surface of the metal member, A process of preparing an electrolyte by mixing a polar solvent with negatively charged cationic microcapsules containing a corrosion inhibitor and an anionic electrodeposition paint, A first electrodeposition coating step involves immersing a metal member in the electrolyte introduced into an electrolytic cell, and applying an electric current with the metal member as the cathode to electrodeposit the cation-type microcapsules onto the surface of the metal member. A second electrodeposition coating step is performed in which the metal member is used as the anode in the electrolytic cell and current is passed through it to electrodeposit the anionic electrodeposition paint onto the surface of the metal member, The process involves baking and curing the anionic electrodeposition paint that has been electrodeposited onto the surface of the metal member to form an electrodeposited coating film. A manufacturing method that includes [details omitted].

7. A process of coating the corrosion inhibitor powder particles with a crosslinking agent, The process involves immersing powder particles coated with the crosslinking agent in an anionic electrodeposition coating to produce anionic microcapsules containing the corrosion inhibitor. A method for manufacturing a coated metal member according to claim 5, further comprising:

8. A process of coating the corrosion inhibitor with a polyaniline-based polymer, The process involves immersing the corrosion inhibitor coated with the polyaniline polymer in an acid solution to dope it with acid, thereby producing anionic microcapsules containing the corrosion inhibitor. A method for manufacturing a coated metal member according to claim 5, further comprising:

9. The method for producing a coated metal member according to claim 8, wherein the acid is an organic acid having a cyclic structure.

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