JP4931127B2 - Corrosion-resistant conductive coating material and method for producing the same - Google Patents

Description

  The present invention relates to a corrosion-resistant conductive coating material on which a π-conjugated conductive polymer film that functions as a corrosion-proof film and a conductive film is formed on a metal substrate, and in particular, a metal such as an acidic atmosphere or a halide solution is used. The present invention relates to a corrosion-resistant conductive coating material that exhibits excellent corrosion resistance and conductivity over a long period in a corrosive environment and a method for producing the same.

  Corrosion-resistant conductive coating materials having high anticorrosive ability and high conductivity are required for uses such as metal separators for fuel cells.

  Hereinafter, the background art will be described by taking a conventional fuel cell separator material as an example.

  The performance required for a fuel cell separator is a gas sealing property that completely separates the oxidant gas and the fuel gas of the adjacent cell, and high electron conductivity that conducts electrons between the front and back surfaces to prevent output reduction due to voltage drop. Good contact resistance characteristics, mechanical characteristics to prevent damage due to stress associated with swelling and shrinkage of the proton conductive electrolyte membrane, corrosion resistance in a low acid atmosphere at high temperatures, and the like.

  The separator is generally made of a resin-impregnated isotropic carbon, a carbon / resin composite material, or a metal material such as stainless steel.

  Resin-impregnated isotropic carbon has high electrical conductivity but is a hard and brittle material. Therefore, machining such as cutting is required to form a gas flow path, which is expensive and inferior in productivity. There's a problem. Carbon / resin composite materials can be manufactured by injection molding and compression molding methods that are inexpensive and highly productive. However, since they are composite materials of porous insulating resin and carbon particles, they have the disadvantage of high gas permeability. If the thickness of the separator is increased in order to solve this problem, the internal resistance increases, which causes a voltage drop in the fuel cell.

  On the other hand, a metal separator is promising as a separator material having high productivity and relatively low cost because of its features such as high mechanical strength, excellent gas sealability, excellent ductility, and easy molding and workability.

  However, since the separator is used at a high temperature of 80 ° C. to 120 ° C. and under an acidic pH of 1 to 2, the metal separator is easily corroded and the metal ions are eluted, and the proton conductive electrolyte membrane is formed. There is a problem of deterioration. Therefore, it is conceivable to use a metal material having excellent corrosion resistance such as stainless steel and titanium for the separator, but this corrosion resistance is derived from a passive film having electrical insulation formed on the metal surface. As a compensation, there is a problem that the contact resistance between the separator and the electrode increases, and the voltage drops to greatly reduce the battery performance.

  Various methods have been proposed in order to obtain good contact resistance and improve the corrosion resistance of the metal separator. For example, in the fuel cell separator disclosed in Patent Documents 1 and 2, by using a metal steel plate such as SUS316 having excellent corrosion resistance as a base material, by applying a noble metal plating such as Au on the base material, good contact resistance and A method for achieving high corrosion resistance for a long period of time has been proposed.

  However, in the case of the methods of Patent Documents 1 and 2, the conventional noble metal plating technology formed on a metal base material such as SUS316 tends to cause pinholes, and the surface of the metal base material such as SUS316 is completely covered. It is difficult. In this technology, in order to activate a metal surface such as SUS316 and improve adhesion, it is common to provide an extremely thin Ni intermediate layer. This causes a local battery to be formed between the noble metal layer and the Ni intermediate layer. End up. As a result, the problem that the Ni intermediate layer melts and the noble metal plating peels cannot be solved. In order to prevent this, there is a method to increase the thickness of the noble metal plating layer, but it is almost impossible in terms of industrial and cost. The metal ions eluted from the pinhole deteriorate the characteristics of the solid polymer electrolyte, and the fuel cell There was a risk of degrading performance.

  Further, in the fuel cell separator disclosed in Patent Document 3, a conductive coating is obtained by dispersing particles of noble metal or conductive metal carbide in an anionic resin or a cationic resin, electrodeposition coating, and baking. A method for coating a metal substrate with a resin is disclosed.

  In this case, mixing noble metals or metal carbides in the resin can prevent corrosion of the base material even in a corrosive environment and maintain conductivity, but in order to maintain high conductivity, a large amount of these fine particles are required. Because it is necessary, it is almost impossible in terms of industrial and cost. Therefore, it is conceivable to reduce the cost by using a corrosion-resistant metal such as Ni or stainless steel flake powder. However, since these materials protect the substrate with an oxide film layer, it is difficult to obtain high conductivity. It was.

  As mentioned above, although the prior art regarding the separator material for fuel cells was demonstrated, the patent document 4 by the present applicant is disclosed regarding the corrosion-resistant conductive coating material. This patent document discloses a corrosion-resistant conductive coating material in which a conductive intermediate layer is formed on a metal substrate and then a π-conjugated conductive polymer layer is formed, but is included in the conductive intermediate layer. Due to the insulating resin component, the electrical resistance of the material itself tends to increase. Furthermore, the conductive intermediate layer has insufficient adhesion to a general-purpose metal, and there is a problem that the conductivity is gradually lost over time, and further improvement in characteristics is required.

JP 2001-068129 A JP 2000-021418 A JP 2004-031166 A JP 2006-167925 A

  In view of the above-mentioned problems of the background art, the object of the present invention is to coat a metal substrate excellent in mass productivity with a π-conjugated conductive polymer layer excellent in corrosion resistance and electrical conductivity, thereby achieving good conductivity. An object of the present invention is to provide a corrosion-resistant conductive coating material that has both properties and corrosion resistance, is inexpensive and has excellent mass productivity, and a method for producing the same.

  As a result of intensive studies, the present inventors have found that at least a part of the π-conjugated conductive polymer layer coated on the metal substrate whose surface has been roughened has etched holes on the surface of the metal substrate. It has been found that by being coated via conductive fine particles adhering to the inside, it is possible to combine corrosion resistance while maintaining good electrical conductivity, and the present invention has been completed.

  That is, the present invention is as follows.

(1) In a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
At least a part of the π-conjugated conductive polymer layer coated on the metal substrate whose surface is etched,
A corrosion-resistant conductive coating material, which is coated with conductive fine particles adhered in the etching hole.

  (2) The metal substrate roughened so that the center line average surface roughness Ra value of the etched metal substrate surface satisfies a condition of Ra ≧ 0.5 μm. The corrosion-resistant conductive coating material according to 1).

(3) The metal substrate is
The corrosion-resistant conductive coating material according to (1) or (2) above, which is at least one metal substrate selected from the group consisting of aluminum, titanium, iron, copper and alloys thereof.

  (4) The corrosion-resistant conductive coating material according to any one of (1) to (3), wherein the conductive fine particles are carbon fine particles composed of graphite and / or carbon black not containing a resin binder.

  (5) The corrosion-resistant conductive coating material according to any one of (1) to (4), wherein the conductive fine particles are carbon fine particles obtained by firing at 600 ° C. or higher.

  (6) The corrosion-resistant conductive coating material according to any one of (1) to (5), wherein the application is a material for electrical contacts, terminals and electrodes.

  (7) The corrosion-resistant conductive coating material according to any one of (1) to (5), wherein the use is a metal separator for a fuel cell.

  (8) The corrosion-resistant conductive coating material according to any one of (1) to (5), wherein the use is an electrode for a dye-sensitized solar cell.

(9) In the method for producing a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
A process of roughening the surface of the metal substrate by degreasing and etching,
A step of impregnating the conductive fine particles in the etching holes by impregnating the etching fine holes with the dispersion solution of the conductive fine particles and then drying;
Removing a part of the conductive fine particles excessively attached in the etching hole and exposing a part of the metal substrate;
A method for producing a corrosion-resistant conductive coating material comprising the step of coating the metal surface with a π-conjugated conductive polymer layer.

(10) In the method for producing a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
A process of roughening the surface of the metal substrate by degreasing and etching,
Attaching conductive fine particles in the etching hole by rubbing graphite and / or carbon black material on the surface of the metal substrate;
Removing a part of the conductive fine particles excessively attached in the etching hole and exposing a part of the metal substrate;
A method for producing a corrosion-resistant conductive coating material comprising the step of coating the metal surface with a π-conjugated conductive polymer layer.

  According to the present invention, in a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer is formed on a metal substrate whose surface is roughened by etching or the like, carbon fine particles, conductive oxide fine particles, noble metal fine particles, etc. The conductive fine particles made of are adhered into the etching holes, and the π-conjugated conductive polymer layer is coated via the conductive fine particles attached to the surface of the metal substrate, so that the metal substrate and the π conjugate Excellent adhesion to the conductive polymer layer and the conductivity is remarkably improved.

  That is, there is a risk that oxygen or moisture that slightly permeates the π-conjugated conductive polymer may generate a highly insulating metal oxide on the surface of the metal substrate. Even if the oxide film layer is formed, etching is performed. Conductive fine particles such as carbon fine particles, conductive oxide particles, or noble metal fine particles attached in the pores maintain a good conductive path between the π-conjugated conductive polymer film and the metal substrate, and provide good contact resistance for a long time. Can be maintained over time.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  When a π-conjugated conductive polymer film is formed by an electropolymerization method using a metal substrate as an anode, since the electropolymerization reaction is an anodic reaction, an oxide film is generally formed at the initial stage of electropolymerization. Even in the case of chemical polymerization, an oxidizing agent is formed on the surface of the metal substrate because an oxidizing agent is used. When used as an electrode for a fuel cell separator or a dye-sensitized solar cell, the current collection characteristics are very important. However, since the oxide film described above is insulative, the electrons are transferred to the metal through the insulating film. It causes energy loss. On the other hand, the insulating oxide film described above has an advantage of excellent corrosion resistance because it can electrochemically suppress the corrosion current. Therefore, a structure for extracting good conductive properties inside the base material while protecting the inside of the base material with an oxide film generated on the surface of the metal base material will be described in detail.

  As shown in FIG. 1, in order to develop both the electrical properties of the metal substrate and the corrosion resistance of the oxide film, it is preferable to first rough the metal substrate. In this roughening, it is desirable to remove the oxide film that hinders electron movement, that is, leads to energy loss. Conventionally known methods such as etching can be used for roughening the surface of the metal substrate. To satisfy the condition of Ra ≧ 0.5 μm as the center line average surface roughness Ra of the base material so that the conductive fine particles can be easily embedded and the metal base material and the conductive fine particles can be bound by the conductive polymer film. It is preferable to select a metal substrate that has been etched. When Ra is less than 0.5 μm, the adhesion and fixing of the conductive fine particles may be insufficient.

  Examples of the etching method described above include a wet etching method, a dry etching method, a blast method, an electrolytic etching method, a reverse sputtering method, and a photo etching method, but a simple wet etching method, a blast method, an electrolytic etching method, and the like are preferable. .

  Next, conductive fine particles adhere to the etching holes, and a conductive path from the inside of the metal substrate to the conductive fine particles is formed by a portion isolated from the corrosive environment, that is, the inside of the metal substrate and the conductive fine particles. Conductivity is maintained even when the surface of the material is oxidized. That is, it is preferable that the surface of the metal substrate and the π-conjugated conductive polymer are in contact with each other through the conductive fine particles attached to the surface of the metal substrate. (See Figure 1)

  When carbon fine particle powder is used as the conductive fine particles embedded in the etching holes, a fine carbon material made of a conductive carbon material not containing a resin binder is suitable. This is because if the resin binder for binding the conductive fine particles and the metal is included, the conductive performance is greatly lowered. In addition, it is more preferable that a hydrophilic functional group such as a hydroxyl group, a sulfonic acid group, or a carboxylic acid group is introduced on the surface of graphite or carbon black because it easily enters the etching hole.

  When a baked carbon material is used as the conductive fine particles embedded in the etching hole, the carbon material such as graphite, amorphous carbon, carbon black, diamond-like carbon, conductive diamond, and carbon nanotube is bonded to the resin, clay, etc. It is preferable to use a carbon material obtained by kneading the material and firing at 600 ° C. or higher.

  The method for embedding the conductive fine particles in the etching holes is not particularly limited, and conventionally known methods can be used. For example, a vacuum or reduced pressure impregnation method, a coating method, a high pressure spray method and the like can be mentioned. A more preferable method is to immerse the etched metal base material in a solvent in which conductive fine particles such as graphite and carbon black are dispersed, and to release the air in the etching holes under reduced pressure, thereby moving the fine particles into the etching holes. Examples thereof include a method of introducing a carbon material such as graphite and carbon black and a method of rubbing a fired carbon material obtained by sintering a mixture of clay and resin under high pressure.

  The conductive fine particles only need to exist in a part of the etching hole. If there are conductive fine particles remaining on the surface of the metal substrate, the conductive fine particles are in close contact with the π-conjugated conductive polymer film formed in the next step. Since it may impair the properties, it is preferable to remove them. At that time, as described above, the conductive fine particles are so formed that at least a part of the π-conjugated conductive polymer layer is coated on the surface of the metal substrate via the conductive material attached to the surface of the metal substrate. Is preferably present only in the etching holes, and at least a part of the surface of the metal substrate is preferably exposed on the conductive polymer layer forming surface. The removal method is not particularly limited, such as a squeegee method or an adhesive tape peeling method, and a conventionally known method can be used.

  Next, in order to improve the corrosion resistance of the metal substrate in which conductive fine particles are embedded in the etching holes and to fix the conductive fine particles in the etching holes, a π-conjugated conductive polymer film is formed on the metal substrate. Let There are many methods for forming a film of a π-conjugated conductive polymer, such as a chemical polymerization method, an electrolytic polymerization method, and a solution method, and an appropriate method depends on the type and form of the target π-conjugated conductive polymer. You can choose the method.

  The kind of the π-conjugated conductive polymer used in the present invention is not particularly limited, but polypyrrole or a derivative thereof, polyalkylthiophene or a derivative thereof, polyalkylenedioxythiophene or a derivative thereof, or polyaniline or a derivative thereof is preferable. .

  In order to obtain a high barrier property for protecting the substrate from high electrical conductivity and corrosive environment, the electrolytic polymerization method or solution method is suitable for polypyrrole or its derivative, and the electrolytic polymerization method or solution is suitable for polyalkylthiophene or its derivative. The chemical polymerization method is preferable, the polyalkylenedioxythiophene or a derivative thereof is preferably a chemical polymerization method, and the polyaniline or a derivative thereof is preferably an electrolytic polymerization method or a solution method. In particular, a π-conjugated conductive polymer film formed by an electropolymerization method has high electrical conductivity due to a high doping rate, and has a high orientation and dense π-conjugated conductive property compared to other formation methods. Since a molecular film can be obtained easily, it is most preferable.

  By the way, the π-conjugated conductive polymer film is formed by an oxidation reaction. Therefore, a portion where the metal is exposed is exposed to an oxidized state, and thus a metal oxide may be generated. Usually, since the metal oxide produced | generated on the metal surface becomes a high resistance component, when applying to energy devices, such as a fuel cell and a solar cell, it becomes a cause which reduces electroconductivity. However, in the present invention, when a π-conjugated conductive polymer film is formed, even if a metal oxide is formed on the metal surface, conductive fine particles such as carbon and metal oxide are in contact with the metal in the etching hole. As a result, a good conductive path is secured.

  In this corrosion-resistant conductive coating material, the π-conjugated conductive polymer film functions to protect the metal substrate and the conductive fine particles from the corrosive environment, but the π-conjugated conductive polymer film has defects. However, since the metal oxide is excellent in corrosion resistance, it also has a function of protecting the substrate from a corrosive environment.

  In addition, the environment in which metals are corroded is not limited to an acidic atmosphere such as an aqueous sulfuric acid solution. For example, an oxidizing atmosphere is formed by oxygen gas on the oxygen electrode side in the fuel cell, and an oxidizing atmosphere is similarly formed by iodine as an electrolyte in the dye-sensitized solar cell. Under such circumstances, certain dopants may cause the electrical conductivity of the π-conjugated conductive polymer to be lost. Therefore, in an oxidative corrosion environment, an anionic compound that is a dopant of the π-conjugated conductive polymer needs to be excellent in oxidation resistance. Therefore, it is preferable to use an anionic compound having a sulfonic acid group or a heteropolyacid group as a dopant for a π-conjugated conductive polymer film that exhibits high electrical conductivity, excellent oxidation resistance, and high corrosion resistance. is there. The number of sulfonic acid groups or heteropolyacid groups in the compound is not particularly limited.

  When the molecular weight of the anionic compound is less than 240, that is, when the molecule is small, the dedoping action is easily generated, and the electrical conductivity of the π-conjugated conductive polymer is lost. In order to prevent this phenomenon, an anionic compound having a large molecule is suitable, and its molecular weight is preferably 240 or more. Specific examples of anionic compounds having one or more sulfonic acid groups or heteropolyacid groups and having a molecular weight of 240 or more include alkylnaphthalene sulfonate ions, lignin sulfonate ions, molybdophosphate ions, and tungstophosphate ions. can do. In addition, a π-conjugated conductive polymer film containing such an anionic compound is dense and has a favorable barrier effect for blocking the corrosive environment from the substrate.

  As a method for forming the π-conjugated conductive polymer film using an anionic compound having a sulfonic acid group or a heteropolyacid group and having a molecular weight of 240 or more as a dopant, for example, when forming a polypyrrole film, A pyrrole as a monomer and a sodium electrolyte such as alkyl naphthalene sulfonate and tetraethylammonium molybtophosphate as a supporting electrolyte are dissolved in an aqueous solution, and a metal substrate in which conductive fine particles are embedded in an etching hole is an anode, and a stainless steel substrate is a cathode. A polypyrrole film can be obtained by an electropolymerization method of electrolyzing as follows. The electrolytic polymerization method for forming a film of polypyrrole or polyaniline is easy to obtain a π-conjugated conductive polymer film having a dense and highly regular electric conductivity, and is excellent in corrosion resistance because of excellent barrier properties.

  In the chemical polymerization method, a π-conjugated conductive polymer film having high corrosion resistance can be formed by contacting a target π-conjugated conductive polymer monomer with an oxidant solution on the substrate surface. it can. For example, in the case of forming a poly-3,4-ethylenedioxythiophene film, on the metal base material in which the conductive fine particles are embedded in the etching holes, the monomer 3,4-ethylenedioxythiophene is oxidized. A poly-3,4-ethylenedioxythiophene coating can be obtained by contacting a butanol-water mixed solution containing iron (III) naphthoquinonesulfonate as an agent. The chemical polymerization method for forming a polythiophene film is easy to obtain a π-conjugated conductive polymer film in which fine particles are densely packed, and is excellent in corrosion resistance because of excellent barrier properties.

  In the solution method, a monomer of a π-conjugated conductive polymer, an oxidant solution, and a dopant solution are brought into contact with each other for polymerization, and the obtained polymer is dried and then dissolved in an organic solvent to obtain a coating solution. If the coating solution is applied to a metal base material in which conductive fine particles are embedded in the etching holes and dried, a desired π-conjugated conductive polymer film having high corrosion resistance can be formed. For example, in the case of forming a film of 3-hexylthiophene, 3-hexylthiophene, ammonium peroxodisulfate as an oxidizing agent, and sodium ferrocenesulfonate as a dopant are dissolved in an ethanol-water mixed solution and polymerized while stirring. The coating liquid can be obtained by proceeding and dissolving the obtained poly-3-hexylthiophenethiophene in toluene after drying. A polyalkylthiophene film can be obtained by applying the coating solution onto a metal substrate in which conductive fine particles are embedded in the etching holes and then drying the coating solution.

  As a method for forming the π conductive polymer film by the solution method, a conventionally known method can be used. For example, screen printing method, dip coating method, roll coating method, spraying method, curtain flow coating method, bar coating method, doctor blade method, brush coating method, etc., there are simple and highly productive dip coating method, brush coating The method is preferred.

  As described above, the formation of the conductive polymer film proceeds by an oxidation reaction. Therefore, since the surface of the metal substrate is exposed to an oxidizing atmosphere when the conductive polymer is formed, an extremely thin insulating metal oxide layer is formed on the surface of the metal substrate. Since the metal oxide layer is excellent in corrosion resistance, it also has a function of protecting internal metal and conductive fine particles from a corrosive environment. Further, at this time, a conductive path is secured by contact between the metal and the conductive fine particle, and contact between the conductive fine particle and the π-conjugated conductive polymer inside the metal, and the good electrical characteristics of the metal are not impaired.

  Examples of the metal substrate include at least one metal substrate selected from the group consisting of aluminum, titanium, iron, copper, and alloys thereof, and productivity, electrical conductivity, and adhesion of π-conjugated conductive polymer. From the viewpoint of safety, titanium and its alloys are preferably used.

  In addition, by forming the π-conjugated conductive polymer after the bending process such as press processing, cutting, etching, etc. on the base material in advance, the π-conjugated system is formed when forming a complex-shaped base material. The effect of the π-conjugated conductive polymer film can be reliably obtained without damaging the conductive polymer film. For example, with respect to the formation of a π-conjugated conductive polymer film, if electrolytic polymerization is performed using the processed substrate as an electrode as described above, even if the substrate surface is uneven due to processing, the π-conjugated system is uniformly formed. A conductive polymer film can be formed, and stable performance can be obtained.

  The thickness of the π-conjugated conductive polymer layer to be formed is suitably 0.001 μm to 100 μm, but is preferably 0.01 μm to 50 μm, and most preferably 0.1 μm to 35 μm from the economical viewpoint.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by the Example. In this example, wt% refers to mass%.

Example 1
AL5052 alloy was used as the metal substrate. The AL5052 alloy plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, polished with water-resistant polishing paper # 120, and then immersed in 3N hydrochloric acid for 30 seconds to remove the oxide film, and the surface is etched to Ra = 3.0 μm. The AL5052 alloy base material was used.

  The etched AL5052 alloy plate is immersed in a dispersion solution (20 wt%) of hydrophilic carbon black (registered trademark Aqua-Black 162) manufactured by Tokai Carbon, and held for 5 minutes under a reduced pressure of 750 mmHg to etch carbon fine particles. After introducing into the hole and releasing the reduced pressure state, drying was performed in a dryer at 90 ° C. for 30 minutes to embed carbon fine particles in the etching hole.

  Rub the surface of the AL5052 alloy substrate with carbon black fine particles embedded in the etching holes using Kim Towel (registered trademark) manufactured by Crecia Co., Ltd., and then dipped in 1N hydrochloric acid for 10 seconds to pickle the excess carbon. The black fine particles were removed, and an AL5052 alloy base material in which the carbon black fine particles were embedded in the etching holes was obtained.

Next, a π-conjugated conductive polymer film containing a compound having a sulfone group as a dopant is formed by electrolytic polymerization. The solvent is pure water, and an electrolyte containing 0.5 mol / L of pyrrole as a monomer and 0.30 mol / L of sodium 2,7-naphthalenedisulfonate as a supporting electrolyte is used. Electrolysis was carried out with a cathode and an electropolymerization time of 1 hour and a current density of 1 mA / cm ² to form a polypyrrole film, and a total of 10 corrosion-resistant conductive coating materials were produced.

(Example 2)
A Ti (JIS type 2) plate was used as the metal substrate. A Ti (JIS type 2) plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, polished with water-resistant abrasive paper # 120, and then immersed in 3 wt% hydrofluoric acid for 60 seconds to remove the oxide film. Etching with a surface with Ra = 2.8 μm A processed Ti (JIS type 2) base material was obtained.

  Shown Denko artificial graphite fine particles UF-G5 was subjected to ultrasonic irradiation for 10 minutes to an aqueous solution adjusted to 20 wt% and sodium dodecylbenzenesulfonate 0.1 wt% to obtain a graphite dispersed aqueous solution. An etched Ti (JIS type 2) base material is immersed in an aqueous graphite dispersion, and held under a reduced pressure of 750 mmHg for 5 minutes to introduce carbon fine particles into the etching hole. After releasing the reduced pressure state, 90 ° C. In the dryer for 30 minutes, and the graphite fine particles were embedded in the etching holes.

  Using a Crescia Co., Ltd. Kim Towel (registered trademark), rubbing the surface of the Ti (JIS type 2) base material in which the graphite fine particles are embedded in the etching holes, followed by dipping in 1N hydrochloric acid for 10 seconds, pickling, and extra The fine graphite particles were removed, and a Ti (JIS type 2) substrate in which the fine graphite particles were embedded in the etching holes was used.

Next, a π-conjugated conductive polymer film containing a compound having a heteropolyacid group as a dopant is formed by electrolytic polymerization. The solvent is pure water, an electrolyte containing 0.5 mol / L of pyrrole as a monomer and 0.30 mol / L of sodium molybdophosphate as a supporting electrolyte, a Ti (JIS type 2) substrate as an anode, SUS304 as a cathode, The electropolymerization time was 1 hour, the current density was 1 mA / cm ² , electropolymerization was performed to form a polypyrrole film, and a total of 10 corrosion-resistant conductive coating materials were produced.

(Example 3)
A SUS430 plate was used as the metal substrate. The SUS430 plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, then shot blasted with titanium nitride beads, then immersed in 1N sulfuric acid for 60 seconds to remove the oxide film, and the surface is etched with Ra = 1.1 μm It was set as the made SUS430 base material.

By repeating the process of rubbing the graphite rod G347 manufactured by Tokai Carbon Co., Ltd. with a pressure of 10 kg / cm ² against the etched SUS430 substrate 5 times, graphite fine particles are introduced into the etching holes. Was embedded in the etching hole.

A polyimide adhesive tape manufactured by Nitto Denko Co., Ltd. was applied to a SUS430 substrate coated with graphite fine particles under a pressure of 5 kg / cm ² and then peeled off to remove excess graphite fine particles. A SUS430 base material embedded in the hole was used.

  Next, a π-conjugated conductive polymer film containing a compound having a sulfonic acid group as a dopant is formed by electrolytic polymerization. Use pure water as solvent, 0.1 mol / L aniline as monomer, 0.15 mol / L polyvinyl sulfonic acid as supporting electrolyte, Au as cathode, see silver / silver chloride (saturated KCl) Electrode, electrode electropolymerization time is 1 hour, electrolysis voltage is 0.5 V (vs silver / silver chloride reference electrode), constant potential electropolymerization is performed for 10 minutes, polyaniline film is formed, and a total of 10 corrosion-resistant conductive coating materials are produced did.

Example 4
150 g of water and 10.1 g of concentrated hydrochloric acid were added to 9.3 g of aniline, and a solution obtained by dissolving 22.8 g of ammonium persulfate in 40 g of water was added dropwise over 2 hours while maintaining the temperature at 0 to 10 ° C., followed by stirring for 3 hours. Thereafter, 41 g of concentrated aqueous ammonia was added dropwise over 1 hour, and the mixture was further stirred for 5 hours. After filtration, water washing and methanol washing were repeated, and vacuum drying was performed to obtain 8.3 g of copper-colored polyaniline. The obtained copper-colored polyaniline was dispersed in 200 ml of methanol, added with 20 g of hydrazine monohydrate, stirred at room temperature for 15 hours, filtered, washed with water and methanol, and vacuum-dried to obtain a grayish blue soluble 7.5 g of polyaniline was obtained. Furthermore, it melt | dissolved in N-methyl-2-pyrrolidone so that it might become 3.5 wt% of indigo trisulfonic acid and 2.0 wt% of polyaniline, and the polyaniline solution containing a dopant was obtained.

  An oxygen-free copper plate was used as the metal substrate. The oxygen-free copper plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, polished with water-resistant abrasive paper # 120, and then immersed in 0.5N nitric acid for 60 seconds to remove the oxide film. Etching with a surface with Ra = 2.1 μm It was set as the processed oxygen-free copper base material.

  In an ethanol solution containing 1 wt% of tetraethylammonium dodecylbenzenesulfonate, a commercially available highly crystalline natural graphite fine particle CSSP-B manufactured by Nippon Graphite Industry Co., Ltd. is adjusted to 20 wt%, and then subjected to ultrasonic waves. Irradiation was performed for 10 minutes to prepare a graphite fine particle dispersion. An oxygen-free copper base material that has been etched is immersed in the graphite fine particle dispersion, and held under a reduced pressure of 750 mmHg for 5 minutes to introduce the graphite fine particles into the etching holes. In the dryer for 30 minutes, and the graphite fine particles were embedded in the etching holes.

  Using a Crescia Co., Ltd. Kim Towel (Registered Trademark), rubbing the surface of the oxygen-free copper base material in which the graphite fine particles are embedded in the etching holes, and removing the excess graphite fine particles, the graphite fine particles are embedded in the etching holes. An oxygen-free copper base material was obtained.

  Next, a π-conjugated conductive polymer film having high corrosion resistance is formed by a solution method. The polyaniline film is formed by repeating the step of immersing the oxygen-free copper base material in which the graphite fine particles are embedded in the etching holes in the previously prepared polyaniline solution and drying at a temperature of 150 ° C. for 10 minutes twice. A total of 10 corrosion-resistant conductive coating materials were produced.

(Example 5)
AL5052 alloy was used as the metal substrate. The AL5052 alloy base material is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, polished with water-resistant polishing paper # 120, and then immersed in 3N hydrochloric acid for 30 seconds to remove the oxide film, and the surface is etched to Ra = 3.0 μm. The AL5052 alloy base material was used.

  In an isopropyl alcohol solution containing 1 wt% of tetraethylammonium dodecylbenzenesulfonate, generally commercially available high-purity artificial graphite fine particles SGP manufactured by SCE are adjusted to 20 wt%, and then subjected to ultrasonic irradiation for 10 minutes. A graphite fine particle dispersion was prepared by carrying out the process. An oxygen-free copper base material that has been etched is immersed in the graphite fine particle dispersion, and held under a reduced pressure of 750 mmHg for 5 minutes to introduce the graphite fine particles into the etching holes. In the dryer for 30 minutes, and the graphite fine particles were embedded in the etching holes.

  Using a Crescia Co., Ltd. Kim Towel (registered trademark), the graphite fine particles on the surface layer of the base material are removed by rubbing the surface of the Ti (JIS type 2) base material in which the graphite fine particles are embedded in the etching holes. The AL5052 alloy base material embedded in the etching hole was used.

  Next, a π-conjugated conductive polymer film having high corrosion resistance is formed by a solution method. In ethanol / water mixed solvent whose pH is adjusted to 7, 3-hexylthiophene 0.4 mol / L, 2,6-anthraquinone disulfonate iron (III) 0.20 mol / L acting as an oxidizing agent and a dopant agent are added. Stir for 6 hours under ice bath temperature. After filtering the solution, the obtained powder was dried under reduced pressure to completely remove the solvent, and the powder was dissolved in a toluene solution to obtain a poly-3-hexylthiophene solution.

  After the solution is uniformly applied to the AL5052 alloy base material in which fine graphite particles are embedded in the etching holes by a spraying method, the process of removing toluene in a dryer at 70 ° C. is repeated to obtain poly-3-hexylthiophene having a thickness of 15 μm. A film was formed to produce 10 corrosion-resistant conductive coating materials.

(Example 6)
A Ti (JIS type 2) plate was used as the metal substrate. A Ti (JIS type 2) plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This base material is degreased with an organic solvent, then polished with water-resistant abrasive paper # 120, and then immersed in 2 wt% oxalic acid for 16 hours to remove the oxide film. Etching with a surface of Ra = 2.8 μm Ti (JIS type 2) base material was obtained.

The graphite particles G347 manufactured by Tokai Carbon Co., Ltd. are introduced into the etching holes by repeating the process of rubbing the Ti (JIS type 2) base material with 10 kg / cm ² of pressure on the etched Ti (JIS type) substrate 5 times. Then, the graphite fine particles were embedded in the etching holes.

A polyimide tape manufactured by Nitto Denko Corporation was applied to a SUS430 substrate coated with graphite fine particles under a pressure of 5 kg / cm ² and then peeled off to remove excess graphite fine particles. A Ti (JIS type 2) base material embedded inside was used.

  Next, a π-conjugated conductive polymer film having high corrosion resistance is formed by a chemical polymerization method. Graphite fine particles contain poly-3,4-ethylenedioxythiophene as a monomer and tetraethylammonium polystyrene sulfonate (average molecular weight 100000) as a dopant agent on the surface of a Ti (JIS type 2) substrate in an etching hole. After applying the ethanol-water mixed solution, an iron (III) chloride aqueous solution that is an oxidant solution is sprayed, and the process of drying at 50 ° C. for 10 minutes is repeated to obtain poly-3,4-ethylenedioxythiophene having a thickness of 21 μm. A film was formed to produce 10 corrosion-resistant conductive coating materials.

(Example 7)
A Ti (JIS type 2) plate was used as the metal substrate. A Ti (JIS type 2) plate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. This substrate is degreased with an organic solvent, polished with water-resistant abrasive paper # 120, immersed in 2 wt% oxalic acid for 16 hours, and then immersed in 0.5 wt% hydrofluoric acid for 30 seconds to form an oxide film. Removal was performed to obtain an etched Ti (JIS type 2) substrate having a surface with Ra = 2.9 μm.

By introducing the graphite rod SS1 made by Showa Denko Co., Ltd. into the etching hole by repeating the process of rubbing the Ti (JIS type 2) base material with 10 kg / cm ² while applying pressure to the Ti (JIS type 2) base material. Then, the graphite fine particles were embedded in the etching holes.

A polyimide tape manufactured by Nitto Denko Corporation was applied to a Ti (JIS type 2) substrate coated with graphite fine particles under a pressure of 5 kg / cm ² and then peeled off to remove excess graphite fine particles. A Ti (JIS type 2) base material in which fine particles were embedded in the etching holes was used.

  A π-conjugated conductive polymer film is formed by a chemical polymerization method. After applying an aqueous solution containing pyrrole as a monomer and iron (III) 2,7-naphthalenedisulfonate as an oxidizing agent on the surface of a Ti (JIS type 2) substrate in which graphite fine particles are embedded in etching holes, The process of drying at 50 ° C. for 10 minutes was repeated to form a polypyrrole film having a thickness of 3 μm.

Subsequently, a π-conjugated conductive polymer film having high corrosion resistance is formed by an electrolytic polymerization method. Etching of fine graphite particles coated with chemically polymerized polypyrrole using an electrolytic solution containing pure water as a solvent, 0.5 mol / L of pyrrole as a monomer, and 0.30 mol / L of dodecylbenzenesulfonic acid as a supporting electrolyte Ti (JIS type 2) base material embedded in the hole is an anode, SUS304 is a cathode, electropolymerization time is 1 hour, current density is 1 mA / cm ² , electropolymerization is performed to form a polypyrrole film having a thickness of 18 μm, A total of 10 corrosion-resistant conductive coating materials were produced.

(Comparative Example 1)
In Example 1, the Al 5052 alloy base material was degreased with an organic solvent, then buffed with 5 μm alumina particles, and then immersed in a 0.01N hydrochloric acid aqueous solution for 30 seconds to remove the oxide film. And a polypyrrole film was formed in the same manner except that the surface was changed to an Al5052 alloy base with Ra = 0.3 μm, and a total of 10 coating materials were produced.

(Comparative Example 2)
In Example 2, except that the electrolytic polymerization step was not performed, a Ti (JIS type 2) base material in which graphite fine particles were embedded in etching holes was produced in the same manner, and a total of 10 coating materials were produced.

(Comparative Example 3)
In Example 3, a SUS430 base material in which graphite fine particles were embedded in the etching holes was prepared in the same manner except that the graphite fine particles were not embedded in the SUS430 base material whose surface was etched. Ten sheets were produced.

  (Comparative Example 4)

In a FE-107 solution, which is a conductive nickel paste manufactured by Fujikura Kasei Co., Ltd., whose viscosity is adjusted with 884 thinner, buffing is performed using 5 μm particle size alumina and the surface roughness is Ra = 0.3 μm. An oxygen-free copper plate etched so as to be immersed was immersed.
The nickel fine particles and the resin binder are introduced into the etching holes for 5 minutes under a reduced pressure of 750 mmHg. After releasing the reduced pressure state, the nickel fine particles are put into the etching holes by drying in a dryer at 50 ° C. for 30 minutes. Embedded.
Thereafter, the nickel fine particle layer containing the excess resin binder on the surface of the oxygen-free copper base material in which the nickel fine particles and the resin binder are embedded in the etching holes is removed using water-resistant abrasive paper # 3000, and the nickel fine particles and the resin binder are removed. A nickel alloy base material embedded in the etching hole was produced.

Next, a polyaniline film, which is a π-conjugated conductive polymer, was formed by chemical polymerization.
150 g of water and 10.1 g of concentrated hydrochloric acid were added to 9.3 g of aniline, and a solution obtained by dissolving 22.8 g of ammonium persulfate in 40 g of water was added dropwise over 2 hours while maintaining the temperature at 0 to 10 ° C., followed by stirring for 3 hours. Thereafter, 41 g of concentrated aqueous ammonia was added dropwise over 1 hour, and the mixture was further stirred for 5 hours, followed by filtration, repeated washing with water and methanol, and then vacuum drying to obtain 8.3 g of copper-colored polyaniline. The obtained copper-colored polyaniline was dispersed in 200 ml of methanol, added with 20 g of hydrazine monohydrate, stirred at room temperature for 15 hours, filtered, washed with water and methanol, and vacuum-dried to obtain a grayish blue soluble 7.5 g of polyaniline was obtained. Furthermore, in addition to toluene solvent so that it might become 3.5 wt% of indigo trisulfonic acid, 2.0 wt% of polyaniline, and 1.0 wt% of dodecylbenzenesulfonic acid, the polyaniline dispersion liquid containing a dopant was obtained.
A polyaniline film is formed by immersing an oxygen-free copper base material in which nickel fine particles are embedded in the etching holes in this polyaniline dispersion and drying it at a temperature of 150 ° C. for 5 minutes to form a polyaniline film. A total of 10 sheets were produced.

(Comparative Example 5)
In Example 5, instead of the poly-3-hexylthiophene film which is a π-conjugated conductive polymer film, a commercially available conductive silver paste XA-874 manufactured by Fujikura Kasei Co., Ltd. was applied by a brush coating method. 10 coating materials were produced in the same manner except that the conductive film was formed by drying at 150 ° C. for 30 minutes.

(Comparative Example 6)
In accordance with JP 2001-234361 A, a phosphorous deoxidized copper plate (20 × 30 mm, thickness 0.2 mm) was used as the metal substrate. The substrate was degreased with an alkaline degreasing solution, subsequently pickled with 10% oxalic acid, and then used as a plating substrate. First, using a Watt bath containing a large amount of nickel chloride having a nickel sulfate hexahydrate of 1.00 mol / L, nickel chloride hexahydrate of 0.25 mol / L, and boric acid of 0.65 mol / L, a current density of 100 mA / A first Ni plating layer having a low sulfur content was formed at cm ² and a bath temperature of 50 ° C. Subsequently, nickel sulfate hexahydrate 1.2 mol / L, nickel chloride hexahydrate 0.19 mol / L, boric acid 0.65 mol / L, sodium 1,5-naphthalene disulfonate 2.33 × 10 ⁻² A second Ni plating layer was formed at a current density of 100 mA / cm ² and a bath temperature of 50 ° C. using a Watt bath having mol / L and thiourea of 1.31 × 10 ⁻³ mol / L. Next, using a commercially available cyan gold plating bath (Uemura Kogyo Co., Ltd .: Allna 556), a gold plating layer was formed at a current density of 800 mA / cm ² and a bath temperature of 50 ° C., and 10 coating materials were produced. .

(Comparative Example 7)
According to Japanese Patent Application Laid-Open No. 2004-31166, 22.4 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 36.95 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane were added to toluene. The mixture was reacted at 60 ° C. for 6 hours to obtain a 60% polyamic resin solution. Formulated to 20 parts by weight of tungsten carbide with respect to 100 parts by weight of polyamic acid resin, dispersed with a pebble mill, then neutralized with triethylamine so that the pH of the water-dispersed product becomes 7, and has a solid content of 20 wt%. An anionic electrodeposition paint was obtained.

  Subsequently, the SUS304 substrate (20 × 30 mm, thickness 0.2 mm) was alkali degreased and then etched and washed in a 10% HF aqueous solution. The SUS304 substrate was immersed in the previously prepared anionic electrodeposition coating (bath temperature 28 ° C.), and coating was performed until the film thickness reached 20 μm. Next, the coated object having the obtained electrodeposition coating film was washed with water and then dried at 170 ° C. for 20 minutes to produce 10 coating materials.

(Evaluation of each material)
The immersion test was carried out for 90 days using the 10 wt% sulfuric acid aqueous solution maintained at 80 ° C., which is a simulated liquid close to the fuel cell operating environment, for the corrosion-resistant conductive coating material according to the present invention and the comparative example. Table 1 shows the results of measuring the concentration of metal ions eluted from the metal base material in the simulated liquid using a sequential high-frequency plasma emission spectrometer and comparing the corrosion resistance (average value obtained five times). Table 2 shows the results of comparison between the initial resistance at a load load of 10 kg / cm ² and after the immersion test by the contact resistance measurement method shown in FIG.

Subsequently, a 30 wt% I ₂ -containing acetonitrile solution maintained at 50 ° C., which is a simulated solution close to the solar cell operating environment, was subjected to 30 immersion tests on the produced corrosion-resistant conductive coating material according to the present invention and the comparative example. Table 3 shows the results of measuring the concentration of metal ions eluted from the metal base material in the simulated solution using a sequential high-frequency plasma emission spectrometer and comparing the corrosion resistance (average value performed five times). Table 4 shows the results of comparing the initial surface resistance and the surface treatment resistance after the immersion test by the surface resistance measurement shown in FIG.

  According to the results of Table 1, each of the corrosion-resistant conductive coating materials according to the present invention protects the substrate with almost no change even after 90 days of the immersion test, and has excellent corrosion resistance characteristics necessary for fuel cell applications. Was recognized. On the other hand, in Comparative Examples 1 and 4 in which the immersion test was conducted in the same manner, the surface roughness was not optimized, so that peeling of the π-conjugated conductive polymer film started as the immersion time increased. It was confirmed that the elution amount of the base material tends to increase. In Comparative Example 2, the metal base material was always dissolved because there was no π-conjugated conductive polymer film protecting the base material from the environment between corrosion. In Comparative Example 5, the conductive silver paste film had no corrosion resistance against the test environment, and silver was dissolved. Furthermore, although the corrosion-resistant conductive coating material produced in Comparative Example 6 had a small elution of the copper base, there was an elution of nickel from the sacrificial nickel layer. In the above comparative examples, elution of metal ions was observed, and it was confirmed that the proton conductivity membrane of the polymer electrolyte fuel cell may be adversely affected.

  According to the results of Table 2, the corrosion-resistant conductive coating material according to the present invention maintains good contact resistance even after 90 days of immersion test and has excellent current collecting characteristics required for solid oxide fuel cell applications. Was recognized. On the other hand, in the corrosion-resistant conductive coating materials produced in Comparative Examples 1 to 7 which were similarly subjected to the immersion test, in Comparative Examples 1 and 4, the adhesion to the metal base material, conductive fine particles, and π-conjugated conductive polymer film It has been found that the contact resistance tends to increase due to the low dipping property since the conductive fine particles and the π-conjugated conductive polymer film start to peel from the metal substrate as the immersion time elapses. In Comparative Examples 3 and 5, it was found that the initial contact resistance was high because appropriate conductive fine particles were not embedded in the metal substrate. Further, in Comparative Example 7, it was confirmed that the contact resistance was high because there were many insulating resin components in the coating. In the above comparative examples, it was confirmed that the contact resistance was high and there was a possibility of adversely affecting the power generation characteristics of the polymer electrolyte fuel cell.

  According to the results in Table 3, each conductive and corrosion-resistant coating material according to the present invention protects the substrate without any change even after 30 days of immersion test, and has the corrosion resistance characteristics necessary for dye-sensitized solar cell applications. It was found to be excellent. On the other hand, in Comparative Examples 1 and 4 in which the immersion test was conducted in the same manner, the surface roughness was not optimized, so that peeling of the π-conjugated conductive polymer film started as the immersion time increased. It was confirmed that the elution amount of the base material tends to increase. In Comparative Example 2, the metal base material was always dissolved because there was no π-conjugated conductive polymer film protecting the base material from the environment between corrosion. In Comparative Example 5, the conductive silver paste film had no corrosion resistance against the test environment, and silver was dissolved. Furthermore, although the corrosion-resistant conductive coating material produced in Comparative Example 6 had a small elution of the copper base, there was an elution of nickel from the sacrificial nickel layer. In the above comparative examples, elution of metal ions was observed, and the metal base material was attacked. Therefore, it was confirmed that sealing of the electrolytic solution was difficult.

  According to the results of Table 4, the corrosion-resistant conductive coating material according to the present invention retains good surface resistance even after 30 days of immersion test, and is excellent in current collection characteristics necessary for dye-sensitized solar cell applications. It was recognized that On the other hand, in the corrosion-resistant conductive coating materials produced in Comparative Examples 1 to 7 which were similarly subjected to the immersion test, in Comparative Examples 1 and 4, the adhesion to the metal base material, conductive fine particles, and π-conjugated conductive polymer film It was found that since the property is low, the conductive fine particles and the π-conjugated conductive polymer film start to peel from the metal substrate with the lapse of the immersion time, and the surface resistance tends to increase. In Comparative Examples 3 and 5, it was found that the initial surface resistance was high because appropriate conductive fine particles were not embedded in the metal substrate. Further, in Comparative Example 7, it was confirmed that the surface resistance was high because there were many insulating resin components in the film. In the above comparative examples, the surface resistance was high, and it was confirmed that the power generation characteristics of the dye-sensitized solar cell might be adversely affected.

  The corrosion-resistant conductive coating material of the present invention is mainly used for metal separators for fuel cells, but can be suitably used for electrical contacts, terminals, and electrodes for dye-sensitized solar cells.

Flow diagram showing the manufacturing process of the corrosion-resistant conductive coating material of the present invention Contact resistance measurement method for evaluating current collection characteristics.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal base material 2 Conductive fine particle layer 3 (pi) conjugated system conductive polymer 4 Metal oxide 11 Load load apparatus 12 Gold electrode 13 Carbon electrode 14 Corrosion-resistant conductive coating material

Claims (10)

In a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
At least a part of the π-conjugated conductive polymer layer coated on the metal substrate whose surface is etched,
A corrosion-resistant conductive coating material, which is coated with conductive fine particles adhered in the etching hole.   2. The metal substrate that has been roughened so that a center line average surface roughness Ra value of the etched metal substrate surface satisfies a condition of Ra ≧ 0.5 μm. Corrosion-resistant conductive coating material. The metal substrate is
The corrosion-resistant conductive coating material according to claim 1 or 2, which is at least one metal substrate selected from the group consisting of aluminum, titanium, iron, copper and alloys thereof.   The corrosion-resistant conductive coating material according to claim 1, wherein the conductive fine particles are carbon fine particles made of graphite and / or carbon black not containing a resin binder.   The corrosion-resistant conductive coating material according to claim 1, wherein the conductive fine particles are carbon fine particles obtained by firing at 600 ° C. or higher.   The corrosion-resistant conductive coating material according to any one of claims 1 to 5, wherein the application is a material for electrical contacts, terminals and electrodes.   The corrosion-resistant conductive coating material according to any one of claims 1 to 5, wherein the use is a metal separator for a fuel cell.   The corrosion-resistant conductive coating material according to any one of claims 1 to 5, wherein the use is an electrode for a dye-sensitized solar cell. In the method for producing a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
A process of roughening the surface of the metal substrate by degreasing and etching,
A step of impregnating the conductive fine particles in the etching holes by impregnating the etching fine holes with the dispersion solution of the conductive fine particles and then drying;
Removing a part of the conductive fine particles excessively attached in the etching hole and exposing a part of the metal substrate;
A method for producing a corrosion-resistant conductive coating material comprising the step of coating the metal surface with a π-conjugated conductive polymer layer. In the method for producing a corrosion-resistant conductive coating material in which a π-conjugated conductive polymer layer is formed on a metal substrate,
A process of roughening the surface of the metal substrate by degreasing and etching,
Attaching conductive fine particles in the etching hole by rubbing graphite and / or carbon black material on the surface of the metal substrate;
Removing a part of the conductive fine particles excessively attached in the etching hole and exposing a part of the metal substrate;
A method for producing a corrosion-resistant conductive coating material comprising the step of coating the metal surface with a π-conjugated conductive polymer layer.

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