JP2007311334A - Separator for fuel cell and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for fuel cell, which is excellent in strength and corrosion resistance and has a low connection resistance; and to provide a method of manufacturing the same. <P>SOLUTION: The separator for the fuel cell includes resin layers with an electrical conductivity and a multilayer structure, which are formed by electrodeposition so as to cover metal substrates, wherein the resin layers contain a conductive material. The separator is manufactured by formation of the resin layers with the multilayer structure, which are formed more than once on the metal substrates by the electrodeposition using an electrodeposition liquid in which the conductive material is dispersed in an electrodepositable resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a separator for a fuel cell, and in particular, a separator used for each unit cell of a fuel cell in which a plurality of unit cells each having an electrode disposed on both sides of a solid polymer electrolyte membrane are connected, and a method for producing such a separator. About.

A fuel cell is simply a device that continuously supplies fuel (reducing agent) and oxygen or air (oxidant) from the outside, and reacts electrochemically to extract electrical energy. It is classified by type, use, etc. Recently, solid oxide fuel cells, molten carbonate fuel cells, phosphoric acid fuel cells, solid polymer electrolyte fuel cells, and alkaline aqueous fuel cells are mainly used depending on the type of electrolyte used. Generally, it is classified into five types.
These fuel cells use hydrogen gas generated from methane or the like as a fuel. Recently, a direct methanol fuel cell (hereinafter also referred to as DMFC) that directly uses an aqueous methanol solution as a fuel is also known. Yes.
In such a fuel cell, a polymer electrolyte fuel cell having a structure in which a solid polymer membrane is sandwiched between two types of catalyst and these members are sandwiched between a gas diffusion layer (GDL) and a separator. (Hereinafter also referred to as PEFC) is attracting attention.

In this PEFC, a unit structure in which an air electrode (oxygen electrode) and a fuel electrode (hydrogen electrode) are arranged on both sides of a solid polymer electrolyte membrane is stacked in order to obtain a desired electromotive force, Or it has the structure which connected two or more in series planarly. For example, in the case of the above-described stack structure, the separator disposed between the unit cells is formed with a fuel gas supply groove for supplying fuel gas to the adjacent unit cell on its side. An oxidant gas supply groove for supplying oxidant gas to the other adjacent unit cell is formed on the other surface.
As such a separator, a metal separator is preferable from the viewpoint of cost and strength, but there is a problem in corrosion resistance. For this reason, metal separators that have been provided with corrosion resistance by forming a conductive electrodeposition coating have been developed (Patent Documents 1, 2, and 3).
JP 2004-31166 A JP 2003-249240 A JP 2004-197225 A

However, in the conventional metal separator in which the electrodeposition coating film is formed on the metal substrate, pinholes are easily generated in the electrodeposition coating film, and thin portions due to thickness unevenness are likely to occur, resulting in deterioration of corrosion resistance and increase in connection resistance. There was a problem of coming.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a separator for a fuel cell that is excellent in strength and corrosion resistance and has low connection resistance, and a method for manufacturing the same.

In order to achieve such an object, the separator of the present invention includes a metal substrate and a conductive and multi-layered resin layer formed by electrodeposition so as to cover the metal substrate. It was set as the structure containing a conductive material.
As another aspect of the present invention, the metal substrate is configured to have a groove on at least one surface.
As another aspect of the present invention, the metal substrate is configured to have a plurality of through holes.
As another aspect of the present invention, the resin layer having a multilayer structure is configured to be heat-treated.
As another aspect of the present invention, the metal substrate is made of stainless steel, aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, magnesium alloy, iron, or iron nickel alloy. .
As another aspect of the present invention, the conductive material is configured to be at least one of carbon particles, carbon nanotubes, carbon nanofibers, carbon nanohorns, and corrosion-resistant metals.
As another aspect of the present invention, the resin layer having a multilayer structure is provided with a metal layer formed of any one of gold, platinum, tin, tin alloy, silver, copper, nickel, palladium, ruthenium, and rubidium between the layers. The configuration was

The method for producing a separator for a fuel cell according to the present invention includes a plurality of steps of forming a resin layer on a metal substrate by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in an electrodepositable resin. It was set as the structure which repeats and forms the resin layer of a multilayer structure.
As another aspect of the present invention, the resin layer is heat-treated every time the resin layers constituting the multilayer resin layer are formed.
In another embodiment of the present invention, the temperature of the heat treatment is within a range of 130 to (T-30) ° C. when a 5% weight reduction temperature of the resin layer material is T (° C.). The configuration.
As another aspect of the present invention, after the heat treatment, at least one treatment of plasma etching, excimer laser irradiation, resin selective etching, ultraviolet irradiation, and surface polishing is performed.
As another aspect of the present invention, after forming a resin layer having a multilayer structure, the resin layer is subjected to at least one treatment of plasma etching, excimer laser irradiation, resin selective etching, ultraviolet irradiation, and surface polishing. did.
As another embodiment of the present invention, each resin layer constituting the resin layer having a multilayer structure is formed of a metal layer made of any one of gold, platinum, tin, tin alloy, silver, copper, nickel, palladium, ruthenium, and rubidium. It was set as the structure which laminates | stacks through this.

  In the separator of the present invention, since the conductive resin layer has a multilayer structure, even if pinholes and thickness unevenness exist in the individual resin layers, such a portion is another resin that constitutes the multilayer structure. It is canceled out by the layer and has high strength and excellent corrosion resistance. Further, when the resin layer having a multilayer structure is heat-treated, pinholes and thin portions with uneven thickness are filled and become uniform, and higher strength and excellent corrosion resistance are provided. Furthermore, when the resin layer having a multilayer structure is subjected to plasma etching treatment, the conductive material contained in the resin layer is exposed to the plasma etching treatment surface, and the connection resistance between the resin layers is further reduced. Also, when a metal layer is provided between the resin layers of the multilayer structure, the connection resistance between the resin layers is further reduced.

  Further, in the separator manufacturing method of the present invention, the process of forming the conductive resin layer by electrodeposition is performed a plurality of times to form a multi-layered resin layer. Even if a thin part is formed, it is filled with another resin layer, and it is possible to form a resin layer having a multilayer structure having excellent corrosion resistance and low connection resistance. Also, by applying heat treatment for each resin layer formation, the film flows into pinholes and thin areas with uneven thickness and becomes uniform, enabling the formation of resin layers with higher strength and excellent corrosion resistance. It becomes. Furthermore, by conducting a plasma etching process on the resin layer having a multilayer structure, the conductive material contained in each resin layer is exposed and the connection resistance between the resin layers can be further reduced. The connection resistance between the resin layers can also be reduced by disposing a metal layer between the resin layers.

Embodiments of the present invention will be described below with reference to the drawings.
[Separator]
FIG. 1 is a partial sectional view showing an embodiment of a separator for a fuel cell of the present invention. In FIG. 1, a separator 1 according to the present invention includes a metal substrate 2, groove portions 3 formed on both surfaces of the metal substrate 2, and a resin layer 5 formed by electrodeposition so as to cover both surfaces of the metal substrate 2. It has. The resin layer 5 has a multilayer structure and contains a conductive material.

FIG. 2 is a partial sectional view showing another embodiment of the separator for a fuel cell of the present invention. In FIG. 2, the separator 11 of the present invention covers both surfaces of a metal substrate 12, a plurality of through holes 13 formed in the metal substrate 12, and the metal substrate 12 including the inner wall surfaces of these through holes 13. And a resin layer 15 formed by electrodeposition. The resin layer 15 has a multilayer structure and contains a conductive material.
The material of the metal bases 2 and 12 constituting the separators 1 and 11 is preferably a material having good electrical conductivity, desired strength, and good workability. For example, stainless steel, aluminum, aluminum alloy, copper, copper alloy , Titanium, titanium alloy, magnesium, magnesium alloy, iron, iron nickel alloy and the like.

  When the separator 1 is incorporated in a fuel cell, one of the groove portions 3 of the metal substrate 2 becomes a fuel gas supply groove portion for supplying fuel gas to an adjacent unit cell, and the other is adjacent to another adjacent one. This is an oxidant gas supply groove for supplying oxidant gas to the unit cell. Further, one of the groove portions 3 may be either a fuel gas supply groove portion or an oxidant gas supply groove portion, and the other may be a cooling water groove. Further, the groove 3 may be provided only on one surface of the metal base 2. The shape of the groove 3 is not particularly limited, and may be a meandering continuous shape, a comb shape, or the like, and the depth, width, and cross-sectional shape are not particularly limited. Further, the shape of the groove 3 may be different between the front and back of the metal base 2.

Further, the through hole 13 provided in the metal base 12 serves as a flow path for supplying fuel gas or oxidant gas to the unit cell when the separator 11 is incorporated into the fuel cell. There is no restriction | limiting in particular in the magnitude | size, the number of such a through-hole 13, and arrangement | positioning density.
The resin layers 5 and 15 having a multilayer structure constituting the separators 1 and 11 are conductive and provide corrosion resistance to the metal bases 2 and 12. For example, the resin layers 5 and 15 are formed by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having electrodeposition properties. It can be hardened and formed into a multilayer structure by repeating the film forming process a plurality of times. The multilayer structure of the resin layers 5 and 15 is not particularly limited as long as it is two or more layers, but for example, a two-layer structure to a five-layer structure is preferable.

Examples of the anionic synthetic polymer resin include acrylic resin, polyester resin, maleated oil resin, polybutadiene resin, epoxy resin, polyamide resin, polyimide resin, etc., and these can be used alone or as a mixture of any combination. Can be used. Moreover, you may use together said crosslinking | crosslinked resin, such as anionic synthetic polymer resin and a melamine resin, a phenol resin, and a urethane resin. On the other hand, examples of the cationic synthetic polymer resin include acrylic resin, epoxy resin, urethane resin, polybutadiene resin, polyamide resin, polyimide resin, and the like. These can be used alone or as a mixture of any combination. Can do. Moreover, you may use together said cationic synthetic polymer resin and crosslinkable resin, such as a polyester resin and a urethane resin.
Further, in order to impart tackiness to the above-described synthetic polymer resin having electrodeposition properties, a tackifier resin such as rosin, terpene, and petroleum resin may be added as necessary.

Such an electrodepositable synthetic polymer resin is subjected to electrodeposition in a state where it is neutralized with an alkaline or acidic substance and solubilized in water, or in an aqueous dispersion state. That is, the anionic synthetic polymer resin is neutralized with amines such as trimethylamine, diethylamine, dimethylethanolamine and diisopropanolamine, and inorganic alkalis such as ammonia and caustic potash. The cationic synthetic polymer resin is neutralized with an acid such as formic acid, acetic acid, propionic acid, or lactic acid. The neutralized water-soluble polymer resin is used in a state of being diluted in water as a water-dispersed type or a dissolved type.
The thickness of the resin layers 5 and 15 having a multilayer structure formed by electrodeposition can be in the range of 0.1 to 100 μm, preferably 3 to 30 μm. If the thickness of the resin layers 5 and 15 is less than 0.1 μm, good corrosion resistance may not be ensured due to the occurrence of pinholes, etc. If the thickness exceeds 100 μm, the occurrence of cracks after drying and solidification and production This is not preferable because of problems such as deterioration in performance and high cost.

  Examples of the conductive material contained in the multilayer resin layers 5 and 15 include carbon materials such as carbon particles, carbon nanotubes, carbon nanofibers, and carbon nanohorns, and corrosion-resistant metals. If a desired material is obtained, the conductive material is not limited to these. In particular, fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are suitable for imparting conductivity to the resin layers 5 and 15. The content of the conductive material in the resin layers 5 and 15 can be set as appropriate according to the conductivity required for the resin layers 5 and 15, for example, in the range of 30 to 90% by weight. Can do.

  Fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are expected to be applied to various fields such as composite materials and electronic devices as nanotechnology materials. When used as a composite material, the physical properties of these can be imparted to the composite material. For example, carbon nanotubes are excellent in terms of electrical conductivity, acid resistance, workability, mechanical strength, etc. When used as a filler in a composite material, the carbon nanotube has excellent physical properties. Can be granted.

In the present invention, the resin layers 5 and 15 having a multilayer structure may be heat-treated. The heat treatment can be performed, for example, in the range of 130 to (T-30) ° C. when the 5% weight reduction temperature of the material of the resin layers 5 and 15 is T (° C.). In the resin layers 5 and 15 having a multilayer structure subjected to such heat treatment, pinholes and thin portions with uneven thickness in each resin layer are filled with other laminated resin layers, and the resin layers 5 and 15 as a whole. As a result, it exhibits higher strength and superior corrosion resistance. If the temperature of the heat treatment is less than 130 ° C., the effect of the heat treatment cannot be sufficiently obtained, and if it exceeds (T-30) ° C., the material of the resin layer becomes brittle or material thinning is not preferable.
The 5% weight reduction temperature T (° C.) of the above material means a temperature at which the weight reduction with respect to the weight at room temperature (25 ° C.) reaches 5% in the thermogravimetric analysis of the material. Here, thermogravimetric analysis is performed by placing the sample in a nitrogen atmosphere and raising the temperature at a rate of 5 ° C./min. The same applies to the following.

In the separator of the present invention, for example, the resin layers 5 and 15 having a multilayer structure may be provided with a metal layer between the layers. The metal layer is preferably made of, for example, one of gold, platinum, tin, tin alloy (for example, tin nickel alloy), silver, copper, palladium, ruthenium, and rubidium. With such a configuration, the connection resistance between the resin layers constituting the resin layers 5 and 15 having a multilayer structure is further reduced. The metal layer can be formed by, for example, a vacuum film formation method such as sputtering, ion plating, or vacuum deposition, an electroplating method, an electroless plating method, or the like. It can set suitably in the range of about 003-0.1 micrometer. If the thickness of the metal layer is less than 0.003 μm, the effect of providing the metal layer cannot be sufficiently obtained, and if the thickness exceeds 0.1 μm, the productivity is lowered and the cost is increased.
The above-described embodiments of the separator of the present invention are examples, and the present invention is not limited to these embodiments.

[Manufacturing method of separator]
Next, the manufacturing method of the separator of this invention is demonstrated.
FIG. 3 is a process diagram for explaining the manufacturing method of the present invention using the separator 1 shown in FIG. 1 as an example. In the manufacturing method of the present invention, first, resists 7 and 7 are formed in a desired pattern on both sides of the metal plate 2 'by photolithography (FIG. 3A), and the metal plates are used from both sides using the resists 7 and 7 as a mask. 2 'is etched to form groove portions 3 and 3 (FIG. 3B). Thereafter, the resists 7 and 7 are removed to obtain the metal substrate 2 (FIG. 3C).
Next, a step of forming a film by electrodeposition on both surfaces of the metal substrate 2 using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having electrodeposition properties. It is repeated a plurality of times and then cured to form a resin layer 5 having a multilayer structure (FIG. 3D). The number of repetitions of the film forming process by electrodeposition can be appropriately set in consideration of the thickness of the resin layer 5 having a multilayer structure, the content of the resin material, the conductive material, and the like, for example, 2 to 5 times. Can do. As described above, since the resin layer 5 having a multilayer structure is formed by a plurality of film forming steps, even if pinholes or thin portions are formed at the film forming stage of each resin layer, such a portion is not treated with another resin. Filled with layers, the entire resin layer 5 having a multilayer structure has excellent corrosion resistance and low connection resistance.

Moreover, in this invention, you may heat-process a resin layer for every film-forming of each resin layer which comprises the resin layer 5 of a multilayer structure. The temperature of this heat treatment can be appropriately set within the range of 130 to (T-30) ° C. when the 5% weight reduction temperature of the material of the resin layer 5 is T (° C.). By performing such a heat treatment, the film flows into a pinhole or a portion where the thickness unevenness is thin and becomes uniform, and a resin layer having higher strength and excellent corrosion resistance can be formed. If the temperature of the heat treatment is less than 130 ° C., the effect of the heat treatment cannot be sufficiently obtained, and if it exceeds (T-30) ° C., the material of the resin layer becomes brittle or material thinning is not preferable.
In the present invention, after each heat treatment of each resin layer, the above heat treatment is performed, and then at least one treatment of plasma etching, excimer laser irradiation, resin selective etching, ultraviolet irradiation, and surface polishing is further performed. You may give it. Alternatively, after each of the resin layers is formed, the heat treatment as described above is performed to form the multilayer resin layer 5, and then plasma etching, excimer laser irradiation, and resin selective etching are performed on the multilayer resin layer 5. In addition, at least one treatment of ultraviolet irradiation and surface polishing may be performed. By performing such a plasma etching process, the conductive material is exposed on the processing surface, and the connection resistance of the resin layer 5 having a multilayer structure can be further reduced.

  Moreover, in this invention, you may make it laminate | stack each resin layer which comprises the resin layer of a multilayer structure through a metal layer. In this case, the metal layer is made of, for example, gold, platinum, tin, tin alloy (for example, tin-nickel alloy), silver, copper, palladium, ruthenium, rubidium, sputtering, ion plating, vacuum deposition, etc. The film can be formed by the vacuum film formation method, the electrolytic plating method, the electroless plating method, or the like. The thickness of the metal layer to be formed can be appropriately set within a range of about 0.03 to 0.1 μm, for example. Thus, by forming each resin layer through the metal layer, the connection resistance between the resin layers can be further reduced.

FIG. 4 is a process diagram for explaining the manufacturing method of the present invention using the separator 11 shown in FIG. 2 as an example. In FIG. 4, resists 17 and 17 are formed in a desired pattern on both surfaces of the metal plate 12 'by photolithography (FIG. 4A). The resists 17 and 17 have a plurality of openings, and the openings are positioned so as to face each other through the metal plate 12 '. Next, using the resists 17 and 17 as a mask, the metal plate 12 'is etched from both sides to form a plurality of through holes 13 (FIG. 4B). Thereafter, the resists 17 and 17 are peeled off to obtain the metal substrate 12 (FIG. 4C).
The through-hole 13 can be formed by a sandblasting method, a laser processing method, a drilling method, or the like in addition to the above-described etching method.

Next, a resin layer 15 having a multilayer structure is formed on the metal substrate 12 including the inner wall surface of the through-hole 13 (FIG. 4D). The multilayer resin layer 15 can be formed in the same manner as the multilayer resin layer 5 described above. Thereby, the separator 11 is obtained.
The above-described embodiments of the separator manufacturing method are examples, and the present invention is not limited to these embodiments.

[Example of fuel cell using separator of the present invention]
Here, an example of a polymer electrolyte fuel cell using the separator of the present invention will be described with reference to FIGS. FIG. 5 is a partial configuration diagram for explaining the structure of the polymer electrolyte fuel cell, and FIG. 6 is a diagram for explaining the membrane electrode assembly constituting the polymer electrolyte fuel cell. FIG. 8 is a perspective view showing the state in which the separator of the polymer electrolyte fuel cell and the membrane electrode assembly are separated from different directions.
5 to 8, the polymer electrolyte fuel cell 21 has a stack structure in which a plurality of unit cells each including a membrane-electrode assembly (MEA) 31 and a separator 41 are stacked. .

As shown in FIG. 6, the MEA 31 includes a fuel electrode (hydrogen electrode) 35 including a catalyst layer 33 and a gas diffusion layer (GDL) 34 disposed on one surface of the polymer electrolyte membrane 32. And an air electrode (oxygen electrode) 38 composed of a catalyst layer 36 and a gas diffusion layer (GDL) 37 disposed on the other surface of the polymer electrolyte membrane 32.
The separator 41 has a fuel gas supply groove 43a on one surface, a separator 41A having an oxidant gas supply groove 44a on the other surface, a fuel gas supply groove 43a on one surface, and the other surface. The separator 41B has a cooling water groove 44b on the surface, and the separator 41C has a cooling water groove 43b on one surface and an oxidant gas supply groove 44a on the other surface. Such separators 41A, 41B, and 41C are separators of the present invention, and a resin layer 5 having a multilayer structure as shown in FIG. 1 is formed on both surfaces thereof, but is omitted in the illustrated example. .

  Two fuel gas supply holes 45a and 45b, two oxidant gas supply holes 46a and 46b, and two cooling water supplies are provided at predetermined positions of the separators 41A, 41B and 41C and the polymer electrolyte membrane 32. Holes 47a and 47b are formed as through holes. Then, the air electrode (oxygen electrode) 38 of the MEA 31 is in contact with the surface of the separator 41A where the oxidizing gas supply groove 44a is formed, and the surface of the separator 41B where the fuel gas supply groove 43a is formed, The fuel electrode (hydrogen electrode) 35 of the MEA 31 abuts, and the surface of the separator 41B on which the cooling water groove 44b is formed and the surface of the separator 41C on which the cooling water groove 43b is formed abut. The separators 41A, 41B, and 41C and the MEA 31 that is a unit cell are stacked, and the polymer electrolyte fuel cell 21 is configured by repeating this process. In the stacked state, the two fuel gas supply holes 45a and 45b form fuel gas supply passages penetrating in the stacking direction, and the two oxidant gas supply holes 46a and 46b are respectively formed. An oxidant gas supply path that penetrates the laminating method is formed, and the two cooling water supply holes 47a and 47b each form a cooling water supply path that penetrates in the laminating direction.

Another example of the polymer electrolyte fuel cell using the separator of the present invention will be described with reference to FIGS. 9 is a plan view for explaining the structure of the polymer electrolyte fuel cell, and FIG. 10 is a longitudinal sectional view taken along line AA of the polymer electrolyte fuel cell shown in FIG. FIG. 2 is a view for explaining a membrane electrode assembly constituting a polymer electrolyte fuel cell.
As shown in FIGS. 9 and 10, the polymer electrolyte fuel cell 51 includes a plurality of unit cells 52 each including a membrane electrode assembly (MEA) 61 and separators 71A and 71B in a planar shape. This is a polymer electrolyte fuel cell that is arranged and electrically connected in series to extract voltages corresponding to the number of unit cells (four in FIG. 9). Further, around each unit cell 52, an insulating portion 55 having substantially the same thickness as this is provided, and the whole is flat. That is, the unit cell 52 and the insulating part 55 are provided in a planar shape by fitting the unit cell 52 into the cut-out part of the flat insulating part 55.

The polymer electrolyte fuel cell 51 is provided with a front and back connection part 57c for penetrating through the insulating part 55 located between adjacent unit cells of the insulating part 55 and connecting the front and back thereof. Then, the front / back connection portion 57c is connected to the separator 71A (for example, the fuel electrode side separator) of one adjacent unit cell via the connection wiring 57a, and the other adjacent one is connected via the connection wiring 57b. The unit cell is connected to a separator 71B (for example, an air electrode side separator). Thereby, adjacent unit cells are electrically connected in series. Wirings 75 and 76 are connected to the separator 71A of the unit cell 52 located at one end connected in series and the separator 71B of the unit cell 52 located at the other end.
In the illustrated example, the number of unit cells is four, but the number of unit cells is not limited.

The insulating part 55 insulates adjacent unit cells from each other except that they are connected by connection parts 57 (connection wirings 57a and 57b and front and back connection parts 57c). The material of the insulating part 55 is not particularly limited as long as it is excellent in terms of processability and durability. For example, glass epoxy, polyimide resin, or the like is used. The insulating portion 55 may be made of only an insulating material or may include a part of a conductive material.
As the front and back connection part 57c of the connection part 57, either a through-hole connection part or a filling via connection part or a bump connection part is provided in the insulating part 55 located between adjacent unit cells. it can. These front and back connection portions 57c can be formed as an application of conventional wiring board technology.

In addition, as shown in FIG. 11, the MEA 61 includes a fuel electrode (hydrogen electrode) composed of a catalyst layer 63 and a gas diffusion layer (GDL) 64 disposed on one surface of the polymer electrolyte membrane 62. ) 65, and an air electrode (oxygen electrode) 68 including a catalyst layer 66 and a gas diffusion layer (GDL) 67 disposed on the other surface of the polymer electrolyte membrane 62.
The separators 71A and 71B are separators of the present invention as shown in FIG. 2, and have a conductive and multi-layered resin layer on a metal substrate having a plurality of through holes.

Next, the present invention will be described in more detail by showing specific examples.
[Example 1]
As the metal plate material, SUS304 (80 mm × 80 mm) having a thickness of 0.8 mm was prepared, and the surface was degreased.
Next, a photosensitive material (a mixture of casein and ammonium dichromate) is applied to both surfaces of this SUS304 by a dip coating method to form a 7 μm-thick coating film, which is exposed through a photomask for groove formation ( A resist was formed by irradiating with a 5 kW mercury lamp for 60 seconds) and developing (spraying with hot water at 40 ° C.).

Next, a ferric chloride solution heated to 70 ° C. was sprayed from both sides of the stainless steel plate through the resist, and half-etching was performed to a predetermined depth. Thereafter, the resist was peeled off with an aqueous caustic soda solution at 80 ° C. and subjected to a cleaning treatment. As a result, a metal substrate having a substantially semicircular cross section having a width of 1 mm and a depth of 0.3 mm, and a groove portion having a length of 1300 mm meandering with a deflection width of 50 mm and a pitch of 2 mm was obtained.
Next, the metal substrate was pretreated with an aqueous hydrochloric acid solution at 40 ° C. (1 part of 35% hydrochloric acid was added to 9 parts of water) and washed with water.
Subsequently, carbon black (Vulcan XC-72 manufactured by Cabot Co., Ltd.) as a conductive material was added to and dispersed in the epoxy electrodeposition liquid by 75% by weight with respect to the resin solid content to obtain an electrodeposition liquid.

  The electrodeposition liquid was stirred at 20 ° C., and the metal substrate was immersed in the electrodeposition solution. Electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 30 seconds, and the pulled metal substrate was washed with pure water. This operation was further repeated once, followed by hot air drying (150 ° C., 3 minutes) with a dryer, and further heat treatment was performed at 180 ° C. for 1 hour in a nitrogen atmosphere. Thereby, a resin layer having a two-layer structure having a thickness of 15 μm was formed so as to cover the metal substrate, and a separator was obtained.

The epoxy electrodeposition solution used was prepared as follows.
First, 1000 parts by weight of diglycidyl ether of bisphenol A (epoxy equivalent 910) was dissolved in 463 parts by weight of ethylene glycol monoethyl ether while maintaining the temperature at 70 ° C. with stirring, and further 80.3 parts by weight of diethylamine was added to 100 parts. An amine epoxy adduct (A) was prepared by reacting at 2 ° C. for 2 hours.
Coronate L (manufactured by Nippon Polyurethane Co., Ltd. diisocyanate: NCO 13% non-volatile content 75% by weight) 875 parts by weight dibutyltin laurate 0.05 parts by weight and heated to 50 ° C., to this, 390 weights of 2-ethylhexanol After that, the mixture was reacted at 120 ° C. for 90 minutes. A component (B) obtained by diluting the obtained reaction product with 130 parts by weight of ethylene glycol monoethyl ether was obtained.

  Next, the mixture consisting of 1000 parts by weight of the above-described amine epoxy adduct (A) and 400 parts by weight of component (B) is neutralized with 30 parts by weight of glacial acetic acid, and then diluted with 570 parts by weight of deionized water. A resin A having a nonvolatile content of 50% by weight was prepared. An epoxy electrodeposition solution was prepared by blending 200.2 parts by weight of this resin A (resin component 86.3 volumes), 583.3 parts by weight of deionized water, and 2.4 parts by weight of dibutyltin laurate.

As a result of measuring the electrical resistance of front and back conduction in the produced separator by the following method, it was 5.9 mΩ, and it was confirmed that the electrical resistance was low.
(Measurement method of electrical resistance)
Separator gas diffusion layer (TGP-H-060 190μm thickness manufactured by Toray Industries, Inc.)
Between the two electrodes, and further sandwiched between 5 mm thick copper-plated copper electrodes (pressure: 20 kgf / cm ² ) to measure the resistance between the electrodes.

Moreover, as a result of conducting a corrosion resistance test on the above-described separator under the following conditions, it was confirmed that the separator had good corrosion resistance.
(Conditions for corrosion resistance test)
Using a spray test solution in which 0.027% by weight of cupric chloride (dihydrate) was added to 5% salt water, a CASS test was conducted at a temperature of 50 ° C. in the spray tank.
When the occurrence of red rust is not observed after a period of time, it is assumed that the corrosion resistance is good.

[Example 2]
In the same manner as in Example 1, a metal substrate having a groove was produced.
Further, an electrodeposition solution was prepared in the same manner as in Example 1.
The electrodeposition solution was stirred at 20 ° C., the metal substrate was immersed in the electrodeposition solution, electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 30 seconds, and the pulled metal substrate was washed with pure water, and then dried. And dried with hot air (150 ° C., 3 minutes), and further subjected to heat treatment at 180 ° C. for 1 hour in a nitrogen atmosphere. This operation was repeated once more. Thereby, a resin layer having a two-layer structure having a thickness of 15 μm was formed so as to cover the metal substrate, and a separator was obtained.
About the separator produced in this way, the electrical resistance of front and back conduction was measured by the same method as in Example 1. As a result, it was 4.9 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 3]
In the same manner as in Example 1, a metal substrate having a groove was produced.
Further, an electrodeposition solution was prepared in the same manner as in Example 1.
The electrodeposition solution was stirred at 20 ° C., the metal substrate was immersed in the electrodeposition solution, electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 30 seconds, and the pulled metal substrate was washed with pure water, and then dried. Was dried with hot air (150 ° C., 3 minutes), further subjected to heat curing treatment at 180 ° C. for 1 hour in a nitrogen atmosphere, and then plasma etching treatment was performed under the following conditions. This operation was repeated once more. Thereby, a resin layer having a two-layer structure having a thickness of 15 μm was formed so as to cover the metal substrate, and a separator was obtained.
(Plasma etching conditions)
-Substrate temperature: 70 ° C
・ RF power: 600W
・ Introduced gas: Oxygen (O ₂ )
・ Etching gas pressure: 30Pa
・ Etching time: 5 minutes

As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 4.2 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 4]
In the same manner as in Example 1, a metal substrate having a groove was produced.
Further, an electrodeposition solution was prepared in the same manner as in Example 1.
The electrodeposition solution was stirred at 20 ° C., the metal substrate was immersed in the electrodeposition solution, electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 30 seconds, and the pulled metal substrate was washed with pure water, and then dried. And dried with hot air (150 ° C., 3 minutes), and further subjected to heat treatment at 180 ° C. for 1 hour in a nitrogen atmosphere.

Next, a metal layer (thickness 0.005 μm) made of a gold thin film was formed on the heat-treated surface by sputtering under the following conditions.
(Metal layer formation conditions)
-Substrate temperature: 70 ° C
・ RF power: 600W
・ Introduction gas: Argon gas ・ Gas introduction pressure: 50 Pa
・ Sputtering time: 20 seconds

Next, again, the film was formed by electrodeposition on the metal layer under the above conditions, and the pulled-up metal substrate was washed with pure water, then dried with hot air (150 ° C., 3 minutes), and further in a nitrogen atmosphere. Heat treatment was performed at 180 ° C. for 1 hour. Thereby, a resin layer having a multilayer structure of resin layer / metal layer / resin layer having a thickness of 15 μm was formed so as to cover the metal substrate, and a separator was obtained.
As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 4.1 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 5]
An aluminum alloy (P5052A) having a size of 80 mm × 80 mm and a thickness of 0.8 mm was prepared as a metal plate material, and the surface was degreased.
Next, a dry film resist (manufactured by Nichigo Morton Co., Ltd.) is laminated on both surfaces of the aluminum alloy to form a 35 μm-thick photosensitive resist layer, and then exposed through a photomask for forming a groove ( A resist was formed by irradiating with a 5 kW mercury lamp for 15 seconds) and developing (spraying a 2% aqueous sodium hydrogen carbonate solution at 30 ° C.).
Next, a ferric chloride aqueous solution heated to 45 ° C. was sprayed from both sides of the aluminum alloy through the resist, and half-etched to a predetermined depth. Thereafter, the resist was peeled off with a 5% aqueous sodium hydrogen carbonate solution at 50 ° C. and subjected to a cleaning treatment. As a result, a metal substrate having a substantially semicircular cross section having a width of 1 mm and a depth of 0.3 mm, and a groove portion having a length of 1300 mm meandering with a deflection width of 50 mm and a pitch of 2 mm was obtained.

Next, pretreatment (passivation film removal) was performed on the metal substrate using an aqueous nitric acid solution, followed by washing with water.
Next, a resin layer having a two-layer structure having a thickness of 15 μm was formed on the metal substrate in the same manner as in Example 3 to obtain a separator.
As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 4.3 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 6]
A copper alloy (copper-chromium-tin alloy) having a size of 80 mm × 80 mm and a thickness of 0.8 mm was prepared as a metal plate material, and the surface was degreased.
Next, a photosensitive material (a mixture of casein and ammonium dichromate) is applied to both surfaces of this copper alloy by a dip coating method to form a 7 μm thick coating film, and exposed through a photomask for forming groove portions. (Irradiated with a 5 kW mercury lamp for 60 seconds) and developed (sprayed with 40 ° C. hot water) to form a resist.
Next, a cupric chloride aqueous solution heated to 70 ° C. was sprayed from both sides of the copper alloy through the resist, and half-etched to a predetermined depth. Thereafter, the resist was peeled off with an aqueous caustic soda solution at 80 ° C. and subjected to a cleaning treatment. As a result, a metal substrate having a substantially semicircular cross section having a width of 1 mm and a depth of 0.3 mm, and a groove portion having a length of 1300 mm meandering with a deflection width of 50 mm and a pitch of 2 mm was obtained.

Next, the metal substrate was pretreated with 50 ° C. sulfuric acid (5 parts of water added to 1 part of sulfuric acid) and washed with water.
Next, a resin layer having a two-layer structure having a thickness of 15 μm was formed on the metal substrate in the same manner as in Example 3 to obtain a separator.
As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 3.8 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 7]
A separator was produced in the same manner as in Example 3 except that the following atmospheric pressure plasma etching process was performed instead of the plasma etching process.
(Atmospheric pressure plasma etching conditions (apparatus: manufactured by Yamato Scientific Co., Ltd.))
-Substrate temperature: 25 ° C
・ RF power: 400W
- introducing gas: He (98%) / H 2 (1%) / CF 4 (1%) mixed gas board conveying speed: 50 mm / sec
As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 3.8 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 8]
A separator was produced in the same manner as in Example 3 except that the following excimer laser irradiation treatment was performed instead of the plasma etching treatment.
(Excimer laser irradiation treatment conditions)
・ Medium: XeCl
・ Oscillation wavelength: 380 nm
・ Pulse power: 125mJ (at 10Hz)
・ Maximum average output: 6W
・ Pulse width: 32nsec
・ Repetition frequency: Max 50Hz
-Processing time: 15 minutes As a result of measuring the electrical resistance of front and back conduction in the separator produced as described above by the same method as in Example 1, it was 4.7 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 9]
A separator was produced in the same manner as in Example 3 except that the following ultraviolet irradiation treatment was performed instead of the plasma etching treatment.
(Ultraviolet irradiation treatment conditions (apparatus: manufactured by Fuji Photo Film Co., Ltd.))
-Substrate temperature: 25 ° C
UV illuminance: 18 mW / cm ² (irradiation distance 10 mm, measurement wavelength 254 nm)
-Processing time: 30 minutes As a result of measuring the electrical resistance of front-back conduction in the separator produced as described above by the same method as in Example 1, it was 3.8 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Example 10]
In the same manner as in Example 1, a resin layer having a two-layer structure was formed on a metal substrate. Next, the resin layer was subjected to the following resin selective etching treatment to obtain a separator.
(Resin selective etching process)
A metal substrate on which a resin layer having a two-layer structure is formed is treated with a resin etching solution (Rohm and
It is immersed for 10 minutes in a 10% diluted solution (80 ° C.) of Circuposit MLB213) manufactured by Haas, and then washed with pure water and dried at 80 ° C. for 30 minutes.
As a result of measuring the electrical resistance of the front and back conduction in the separator produced as described above by the same method as in Example 1, it was 5.0 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the above-described separator under the same conditions as in Example 1, it was confirmed that the separator had good corrosion resistance.

[Example 11]
In the same manner as in Example 1, a resin layer having a two-layer structure was formed on a metal substrate. Next, this resin layer was subjected to the following surface polishing treatment to obtain a separator.
(Surface polishing treatment)
The surface of the two-layered resin layer is polished using # 400 polishing paper.
As a result of measuring the electrical resistance of front and back conduction in the separator produced as described above by the same method as in Example 1, it was 4.8 mΩ, and it was confirmed that the electrical resistance was low.
Moreover, as a result of conducting a corrosion resistance test on the separators under the same conditions as in Example 1, it was confirmed that the separators had good corrosion resistance.

[Comparative example]
In the same manner as in Example 1, a metal substrate having a groove was produced.
Further, an electrodeposition solution was prepared in the same manner as in Example 1.
The electrodeposition solution was stirred at 20 ° C., the metal substrate was immersed in the electrodeposition solution, electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 1 minute, and the pulled metal substrate was washed with pure water, and then dried. And dried with hot air (150 ° C., 3 minutes), and further subjected to heat treatment at 180 ° C. for 1 hour in a nitrogen atmosphere. Thereby, a resin layer having a thickness of 15 μm was formed so as to cover the metal substrate, and a separator was obtained.

As a result of measuring the electrical resistance of conduction between the front and back sides of the separator thus produced by the same method as in Example 1, it was 8.4 mΩ, which was higher than that of the separators in Examples 1 to 11. .
Moreover, about said separator, as a result of performing a corrosion resistance test on the same conditions as Example 1, red rust has generate | occur | produced in 600 hours progress, and the corrosion resistance was inferior compared with the separator of Examples 1-11. .

  The present invention can be applied to the manufacture of a fuel cell in which a plurality of unit cells each having an electrode disposed on both sides of a solid polymer electrolyte membrane are connected.

It is a fragmentary sectional view showing one embodiment of a separator for fuel cells of the present invention. It is a fragmentary sectional view which shows other embodiment of the separator for fuel cells of this invention. It is process drawing for demonstrating one Embodiment of the manufacturing method of the separator of this invention. It is process drawing for demonstrating other embodiment of the manufacturing method of the separator of this invention. It is a partial block diagram for demonstrating an example of the polymer electrolyte fuel cell using the separator of this invention. It is a figure for demonstrating the membrane electrode assembly which comprises the polymer electrolyte fuel cell shown by FIG. FIG. 6 is a perspective view showing a state where the separator and the membrane electrode assembly of the polymer electrolyte fuel cell shown in FIG. 5 are separated from each other. FIG. 6 is a perspective view showing a state in which the separator and the membrane electrode assembly of the polymer electrolyte fuel cell shown in FIG. 5 are separated from a direction different from FIG. 7. It is a top view for demonstrating the other example of the polymer electrolyte fuel cell using the separator of this invention. It is a longitudinal cross-sectional view in the AA line of the polymer electrolyte fuel cell shown by FIG. It is a figure for demonstrating the membrane electrode assembly which comprises the polymer electrolyte fuel cell shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separator 2 ... Metal base | substrate 3 ... Groove part 5 ... Resin layer 11 ... Separator 12 ... Metal base | substrate 13 ... Through-hole 15 ... Resin layer 21, 51 ... Polymer electrolyte fuel cell 31, 61 ... Membrane electrode assembly (MEA)
41A, 41B, 41C, 71A, 71B ... separator

Claims (13)

  A separator for a fuel cell, comprising: a metal substrate; and a conductive multi-layered resin layer formed by electrodeposition so as to cover the metal substrate, wherein the resin layer contains a conductive material.   The separator for a fuel cell according to claim 1, wherein the metal substrate has a groove on at least one surface.   The separator for a fuel cell according to claim 1, wherein the metal substrate has a plurality of through holes.   4. The fuel cell separator according to claim 1, wherein the resin layer having a multilayer structure is heat-treated. 5.   The metal substrate is made of any one of stainless steel, aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, magnesium alloy, iron, and iron-nickel alloy. The separator for fuel cells in any one.   The fuel cell separator according to any one of claims 1 to 5, wherein the conductive material is at least one of carbon particles, carbon nanotubes, carbon nanofibers, carbon nanohorns, and corrosion-resistant metals.   The said resin layer of a multilayer structure equips an interlayer with the metal layer which consists of any 1 type of gold | metal | money, platinum, tin, a tin alloy, silver, copper, nickel, palladium, ruthenium, rubidium, The 1 thru | or characterized by the above-mentioned. The separator for fuel cells according to claim 6.   A process of forming a resin layer by electrodeposition on a metal substrate using an electrodeposition liquid in which a conductive material is dispersed in an electrodepositable resin is performed a plurality of times to form a multi-layered resin layer. A method for producing a fuel cell separator.   9. The method for producing a fuel cell separator according to claim 8, wherein the resin layer is subjected to heat treatment every time the resin layers constituting the multilayer resin layer are formed.   The temperature of the heat treatment is within a range of 130 to (T-30) ° C, where T (° C) is a 5% weight reduction temperature of the material of the resin layer. Manufacturing method of fuel cell separator.   11. The fuel cell separator according to claim 9, wherein after the heat treatment, at least one of plasma etching, excimer laser irradiation, resin selective etching, ultraviolet irradiation, and surface polishing is performed. Manufacturing method.   11. The method according to claim 9, wherein after forming the resin layer having a multilayer structure, the resin layer is subjected to at least one treatment of plasma etching, excimer laser irradiation, resin selective etching, ultraviolet irradiation, and surface polishing. The manufacturing method of the separator for fuel cells as described in any one of.   Each resin layer constituting the multi-layered resin layer is laminated and formed through a metal layer made of any one of gold, platinum, tin, tin alloy, silver, copper, nickel, palladium, ruthenium, and rubidium. A method for producing a fuel cell separator according to any one of claims 8 to 12.

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