JP2010140782A - Separator for fuel cell, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for a fuel cell having superior strength and corrosion resistance, and small connection resistance, and also provide its manufacturing method. <P>SOLUTION: In the separator for the fuel cell, a metal substrate 2 having groove parts 3 on at least one face, and a conductive resin layer 4 formed by electrodeposition so as to cover the entire face including a front face 2A, a rear face 2B, and the groove parts 3 of this metal substrate 2 are equipped. A region to cover the front face 2A and the rear face 2B of the metal substrate 2 out of the conductive resin layer 4 is made to have a flat face in a state that fine recessed parts 4a formed in the conductive resin layer 4 are filled with a corrosion resistant resin layer 5a. Other regions of the conductive resin layer 4 including the region to cover the groove parts 3 are covered with a corrosion resistant resin layer 5b, the conductive resin layer 4 contains a conductive material, and the corrosion resistant resin layers 5a, 5b are made to have electrically insulating properties. <P>COPYRIGHT: (C)2010,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 formed with a conductive electrodeposition coating to impart corrosion resistance have been developed (Patent Documents 1, 2, and 3).
JP 2004-31166 A JP 2003-249240 A JP 2004-197225 A

However, in a conventional metal separator in which an electrodeposition coating is formed on a metal substrate, there is a high possibility that pinholes will occur due to hydrogen gas generated during the formation of the electrodeposition coating, outgassing during thermosetting, etc. Thin portions due to unevenness are likely to occur, and there is a problem that the corrosion resistance is deteriorated and the connection resistance is increased. In particular, when a metal having low corrosion resistance such as aluminum is used as the metal substrate, the generation of pinholes is a serious problem when used as a fuel cell separator.
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 is formed by electrodeposition so as to cover a metal substrate having a groove on at least one surface and both the front and back surfaces of the metal substrate and the entire surface including the groove. A region of the conductive resin layer that covers both the front and back surfaces of the metal substrate is formed by filling a fine recess formed in the conductive resin layer with a corrosion-resistant resin layer to form a flat surface. And the other region of the conductive resin layer including the region covering the groove is covered with a corrosion-resistant resin layer, the conductive resin layer contains a conductive material, and the corrosion-resistant resin layer is electrically insulated. It was set as the structure which is sex.

  The separator of the present invention comprises a metal substrate having a plurality of through holes, and a conductive resin layer formed by electrodeposition so as to cover both the front and back surfaces of the metal substrate and the entire surface including the wall surfaces of the through holes. A region of the conductive resin layer that covers both the front and back surfaces of the metal substrate is formed with a flat surface formed by filling a fine recess formed in the conductive resin layer with a corrosion-resistant resin layer, and the wall surface of the through hole The other region of the conductive resin layer including the region covering the surface is covered with a corrosion-resistant resin layer, the conductive resin layer contains a conductive material, and the corrosion-resistant resin layer is electrically insulating. The configuration was

As another aspect of the present invention, 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. .
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.

  The method for producing a separator for a fuel cell according to the present invention uses an electrodeposition liquid in which a conductive material is dispersed in a resin having electrodeposition properties, and both the front and back surfaces of a metal substrate having grooves on at least one surface and the grooves. Forming a conductive resin layer on the metal substrate by electrodeposition so as to cover the entire surface including the electrodeposition, and electrodeposition so as to cover the conductive resin layer using an electrically insulating and corrosion-resistant electrodeposition paint A step of forming a corrosion-resistant resin layer, and removing only regions of the corrosion-resistant resin layer covering the conductive resin layers located on both the front and back surfaces of the metal substrate to expose the conductive resin layer, thereby forming a flat surface. And a forming step.

Further, the method for producing a separator for a fuel cell according to the present invention uses an electrodeposition liquid in which a conductive material is dispersed in an electrodepositable resin, and both the front and back surfaces of a metal substrate having a plurality of through holes and the penetration A step of forming a conductive resin layer on the metal substrate by electrodeposition so as to cover the entire surface including the wall surface of the hole, and a coating of the conductive resin layer using an electrically insulating and corrosion-resistant electrodeposition paint. Forming a corrosion-resistant resin layer by electrodeposition, and removing only the region of the corrosion-resistant resin layer covering the conductive resin layer located on both the front and back surfaces of the metal substrate to expose the conductive resin layer. And a step of forming a flat surface.
As another aspect of the present invention, the corrosion-resistant resin layer is formed by depositing a corrosion-resistant electrodeposition paint so as to cover the conductive resin layer by electrodeposition, and then heat-treating the corrosion-resistant electrodeposition paint to heat flow. It was set as the structure which forms.

  The separator of the present invention is provided with corrosion resistance by the conductive resin layer covering the metal substrate. Further, in the region of the conductive resin layer covering both the front and back surfaces of the metal substrate, the fine recesses generated in the conductive resin layer. Since a flat surface is formed by being filled with a corrosion-resistant resin layer, stable corrosion resistance is maintained on both the front and back surfaces of the metal substrate, and the surface contact resistance of the separator is further reduced. Other regions of the conductive resin layer including the region to be coated are coated with the corrosion-resistant resin layer, so that the corrosion resistance in these regions is higher, thereby providing high strength and excellent corrosion resistance. Become.

  In the method for producing a separator of the present invention, a conductive resin layer is formed by electrodeposition, and thereafter, an electrically insulating and corrosion-resistant electrodeposition coating is used to coat the conductive resin layer so as to cover the conductive resin layer. Therefore, even if a pinhole or a fine recess that is a thin part is formed in the formation step of the conductive resin layer by electrodeposition, the fine recess is surely filled by the formation of the corrosion-resistant resin layer by electrodeposition, The conductive resin layer is coated with a corrosion-resistant resin layer, and thereafter, only the corrosion-resistant resin layer covering both the front and back surfaces of the metal substrate is removed to form a flat surface with the conductive resin layer exposed, and the other areas of the corrosion-resistant resin layer Is left as it is, it is possible to produce a separator having excellent corrosion resistance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Separator]
FIG. 1 is a partial cross-sectional view showing an embodiment of a separator for a fuel cell of the present invention, and FIG. 2 is an enlarged partial cross-sectional view of a portion surrounded by a chain line in FIG. 1 and 2, a separator 1 of the present invention includes a metal substrate 2, a groove portion 3 formed on both surfaces of the metal substrate 2, a metal including the front surface 2 </ b> A, the back surface 2 </ b> B, and the groove portion 3 of the metal substrate 2. And a conductive resin layer 4 formed by electrodeposition so as to cover the entire surface of the substrate 2. Further, in the conductive resin layer 4, the region covering the front surface 2 </ b> A and the back surface 2 </ b> B of the metal substrate 2 is formed by filling the fine recesses 4 a generated in the conductive resin layer 4 with the corrosion-resistant resin layer 5 a and forming a flat surface. Has been. Furthermore, the other region of the conductive resin layer 4, that is, the region covering the groove 3 and the end face 2C of the metal substrate 2 is covered with the corrosion-resistant resin layer 5b. The conductive resin layer 4 contains a conductive material, and the corrosion-resistant resin layers 5a and 5b are electrically insulating.

  3 is a partial cross-sectional view showing another embodiment of the separator for a fuel cell of the present invention, and FIG. 4 is an enlarged partial cross-sectional view of a portion surrounded by a chain line in FIG. 3 and 4, the separator 11 of the present invention includes a metal substrate 12, a plurality of through holes 13 formed in the metal substrate 12, a front surface 12 </ b> A, a back surface 12 </ b> B, and the through holes 13 of the metal substrate 12. And a conductive resin layer 14 formed by electrodeposition so as to cover the entire surface of the metal substrate 12 including the wall surface. Further, in the conductive resin layer 14, the region covering the front surface 12 </ b> A and the back surface 12 </ b> B of the metal substrate 12 is formed with a flat surface by filling the fine recesses 14 a generated in the conductive resin layer 14 with the corrosion-resistant resin layer 15 a. Has been. Further, the other region of the conductive resin layer 14, that is, the region covering the wall surface of the through hole 13 and the end surface 12 </ b> C of the metal substrate 12 is covered with the corrosion resistant resin layer 15 b. The conductive resin layer 14 contains a conductive material, and the corrosion-resistant resin layers 15a and 15b are electrically insulating.

The material of the metal substrates 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 serves as 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 an 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. Furthermore, the groove part 3 may be provided only on one surface of the metal substrate 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 substrate 2.

Further, the through hole 13 of the metal substrate 12 serves as a flow path for supplying fuel gas or oxidant gas to the unit cell when the separator 11 is incorporated in 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 conductive resin layer 4 constituting the separator 1 and the conductive resin layer 14 constituting the separator 11 have conductivity and are for imparting corrosion resistance to the metal substrates 2 and 12. The film can be formed by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having, and then cured. Further, in the present invention, the fine recesses 4a and 14a generated in the conductive resin layers 4 and 14 are pinholes generated during the formation of the conductive resin layers 4 and 14, as shown in FIGS. It is a thin part. Therefore, the number and positions of the fine recesses 4a and 14a are not defined at all, and the case where the fine recesses 4a and 14a are not present in the conductive resin layers 4 and 14 falls within the scope of the present invention.

The corrosion-resistant resin layers 5a and 15a are filled with the fine concave portions 4a and 14a generated in the conductive resin layers 4 and 14 as described above, and the corrosion resistance of the conductive resin layers 4 and 14 in the fine concave portions 4a and 14a is reduced. The corrosion-resistant resin layers 5b and 15b cover the conductive resin layers 4 and 14 located on the wall surfaces of the grooves 3 and the through holes 13 and the end portions 2C and 12C of the metal substrates 2 and 12, respectively. Corrosion resistance is further improved. Such corrosion-resistant resin layers 5a and 15a and corrosion-resistant resin layers 5b and 15b can be formed using an electrically insulating and corrosion-resistant electrodeposition paint. Examples of the resin constituting the corrosion-resistant electrodeposition coating material include various anionic or cationic synthetic polymer resins having electrodeposition properties.
The thickness of the conductive resin layers 4 and 14 formed by electrodeposition can be in the range of 1 to 50 μm, preferably 10 to 30 μm. If the thickness of the conductive resin layers 4 and 14 is less than 1 μm, the frequency of occurrence of defective portions such as pinholes and uneven thickness may be too high, and repair by the corrosion resistant resin layers 5a and 15a may be incomplete. On the other hand, if the thickness of the conductive resin layers 4 and 14 exceeds 50 μm, it may cause cracking after drying and solidification, decrease in productivity, and increase in manufacturing cost.

  On the other hand, the thickness of the corrosion-resistant resin layers 5a and 15a may be a thickness sufficient to fill the fine recesses 4a and 14a and make the surfaces of the conductive resin layers 4 and 14 flat. Therefore, the corrosion-resistant resin layers 5a and 15a The thickness of 15a becomes below the thickness of the conductive resin layers 4 and 14. Further, the corrosion-resistant resin layers 5b and 15b only need to be thick enough to fill the fine recesses 4a and 14a with the corrosion-resistant resin layers 5a and 15a. For example, the thickness is equal to or greater than the thickness of the conductive resin layers 4 and 14, and the upper limit is It is about 30 μm, preferably about 10 μm. If the thickness of the corrosion-resistant resin layers 5a and 15a exceeds 30 μm, it may cause cracking after drying and solidification, decrease in productivity, and increase in manufacturing cost, which is not preferable.

  Examples of the conductive material contained in the conductive resin layers 4 and 14 include carbon materials such as carbon particles, carbon nanotubes, carbon nanofibers, and carbon nanohorns, and corrosion resistant metals. However, acid resistance and conductivity are desirable. If what is obtained is not limited to these conductive materials. In particular, fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are suitable for imparting conductivity to the resin layer. The content rate of such a conductive material can be appropriately set according to the conductivity required for the conductive resin layers 4 and 14, and can be set in the range of 30 to 70% by weight, for example.

In the present invention, corrosion resistance is imparted by the conductive resin layers 4 and 14 covering the metal substrates 2 and 12. Further, in the regions of the conductive resin layers 4 and 14 that cover both the front and rear surfaces of the metal substrates 2 and 12, the corrosion-resistant resin layers 5a and 15a are filled in the fine recesses 4a and 14a generated in the conductive resin layers 4 and 14, respectively. Thus, since the flat surface is formed, the corrosion resistance on both the front and back surfaces of the metal substrates 2 and 12 is reliably exhibited, and the surface contact resistance of the separator is reduced. Further, since the other regions of the conductive resin layers 4 and 14 including the region covering the wall surface of the groove 3 or the through hole 13 are covered with the corrosion resistant resin layers 5b and 15b, the corrosion resistance in these regions is higher. Accordingly, the separators 1 and 11 have high strength and excellent corrosion resistance.
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. 5 is a process diagram for explaining the manufacturing method of the present invention using the separator 1 shown in FIGS. 1 and 2 as an example. In the manufacturing method of the present invention, first, resists 7 and 7 are formed in a desired pattern on both surfaces of the metal plate 2 'by photolithography, and the metal plate 2' is etched from both sides using the resists 7 and 7 as a mask. 3 and 3 are formed (FIG. 5A). Thereafter, the resists 7 and 7 are removed to obtain the metal substrate 2 (FIG. 5B).
Next, on the entire surface of the metal substrate 2 (in the illustrated example, the front surface 2A, the back surface 2B, the end surface 2C, and the groove portion 3), conductive materials in various anionic or cationic synthetic polymer resins having electrodeposition properties are placed. A film is formed by electrodeposition using the dispersed electrodeposition liquid, and then cured to form a conductive resin layer 4 containing a conductive material (FIG. 5C).

Examples of the anionic synthetic polymer resin used for forming the conductive resin layer 4 include acrylic resin, polyester resin, maleated oil resin, polybutadiene resin, epoxy resin, polyamide resin, polyimide resin, and the like. It can be used alone or as a mixture in any combination. 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.
In addition, examples of the conductive material used include carbon materials such as carbon particles, carbon nanotubes, carbon nanofibers, and carbon nanohorns, and corrosion-resistant metals, but if an acid-resistant and conductive material is obtained, It is not limited to these conductive materials. In particular, fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are suitable for imparting conductivity to the resin layer.

The formation of the conductive resin layer 4 as described above is performed by setting the electrodeposition conditions so as not to cause thin portions due to pinholes or uneven thickness in the conductive resin layer 4, but occurs when the electrodeposition film is formed. In some cases, fine recesses 4a such as pinholes or thin portions due to thickness unevenness may occur due to hydrogen gas to be discharged or outgassing during thermosetting.
Next, a corrosion-resistant resin layer 5 is formed by electrodeposition so as to cover the conductive resin layer 4 using an electrically insulating corrosion-resistant electrodeposition paint (FIG. 5D). Then, only the area | region which coat | covers the conductive resin layer 4 located in the surface 2A and the back surface 2B of the metal substrate 2 among the corrosion-resistant resin layers 5 is removed, and the conductive resin layer 4 is exposed to form a flat surface ( FIG. 5 (E)). Thereby, the area | region which coat | covers the surface 2A and the back surface 2B of the metal substrate 2 among the conductive resin layers 4 is filled with the corrosion-resistant resin layer 5 as the corrosion-resistant resin layer 5a in the fine recessed part 4a which has arisen in the conductive resin layer 4. In this state, a flat surface is formed. Further, the other region of the conductive resin layer 4, that is, the region covering the groove 3 and the end surface 2C of the metal substrate 2 is covered with the corrosion-resistant resin layer 5b in which the corrosion-resistant resin layer 5 is left as it is. 1 is obtained.

As the corrosion-resistant electrodeposition paint, for example, a paint containing various anionic or cationic synthetic polymer resins having electrodeposition properties as mentioned in the formation of the conductive resin layer 4 can be used. .
Alternatively, the corrosion-resistant resin layer 5 may be formed by attaching a corrosion-resistant electrodeposition coating so as to cover the conductive resin layer by electrodeposition and then heat-treating the corrosion-resistant electrodeposition coating. In this case, the melting temperature of the resin used for forming the corrosion-resistant resin layer 5b is preferably lower than the melting temperature of the resin constituting the conductive resin layer 4, for example, the melting temperature of the resin constituting the conductive resin layer 4 Can be used by appropriately selecting those having a temperature difference of about 5 to 30 ° C. In addition, the heat treatment after the corrosion-resistant electrodeposition paint is attached on the conductive resin layer 4 is lower than the melting temperature of the resin constituting the conductive resin layer 4 and higher than the melting temperature of the corrosion-resistant resin used. The heating means is not particularly limited.

Moreover, the removal of only the area | region which coat | covers the conductive resin layer 4 located in the surface 2A and the back surface 2B of the metal substrate 2 among the corrosion-resistant resin layers 5 is performed by grinding using a buffing machine, a roll type polishing machine or the like. Can do.
FIG. 6 is a process diagram for explaining the manufacturing method of the present invention using the separator 11 shown in FIGS. 3 and 4 as an example. In FIG. 6, a resist 17 having a pattern shape having a plurality of openings by photolithography on both surfaces of the metal plate 12 ', and each opening is positioned so as to face each other with the metal plate 12' interposed therebetween. 17 is formed. Next, using the resists 17 and 17 as a mask, the metal plate material 12 'is etched from both sides to form a plurality of through holes 13 (FIG. 6A). Thereafter, the resists 17 and 17 are removed to obtain the metal substrate 12 (FIG. 6B).
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, the conductive resin layer 14 is formed on the entire surface of the metal substrate 12 (in the illustrated example, the front surface 12A, the back surface 12B, the end surface 12C, and the inner wall surface of the through hole 13) (FIG. 6C). The formation of the conductive resin layer 14 can be performed in the same manner as the formation of the conductive resin layer 4 described above, and the electrodeposition conditions are set so as not to cause thin portions due to pinholes or uneven thickness in the conductive resin layer 14. Set and done. However, there are cases where fine recesses 14a such as pinholes or thin portions due to thickness unevenness are generated by hydrogen gas generated during the formation of the electrodeposition coating, or outgassing during thermosetting.
Next, the corrosion-resistant resin layer 15 is formed by electrodeposition using an electrically insulating corrosion-resistant electrodeposition coating so as to cover the conductive resin layer 14 (FIG. 6D). The formation of the corrosion-resistant resin layer 15 can be performed in the same manner as the formation of the corrosion-resistant resin layer 5 described above.

  Next, only the area | region which coat | covers the conductive resin layer 14 located in the surface 12A and the back surface 12B of the metal substrate 12 among the corrosion-resistant resin layers 15 is removed, and the conductive resin layer 14 is exposed to form a flat surface. (FIG. 6 (E)). Thereby, the area | region which coat | covers the surface 12A and the back surface 12B of the metal substrate 12 among the conductive resin layers 14 is filled with the corrosion-resistant resin layer 15 as the corrosion-resistant resin layer 15a in the fine recessed part 14a which has arisen in the conductive resin layer 14. In this state, a flat surface is formed. Further, the other region of the conductive resin layer 14, that is, the region covering the inner wall surface of the through-hole 13 and the end surface 12 </ b> C of the metal substrate 12 was covered with the corrosion-resistant resin layer 15 b with the corrosion-resistant resin layer 15 left as it is. Thus, the separator 11 is obtained. In addition, the removal of only the area | region which coat | covers the conductive resin layer 14 located in the surface 12A and the back surface 12B of the metal substrate 12 among the corrosion-resistant resin layers 15 is performed by grinding using a buffing machine, a roll type polishing machine or the like. Can do.

In such a separator manufacturing method of the present invention, the conductive resin layers 4 and 14 are formed by electrodeposition, and then the conductive resin layers 4 and 14 are coated using an electrically insulating and corrosion-resistant electrodeposition paint. Thus, the corrosion-resistant resin layers 5 and 15 are formed by electrodeposition as described above, so that even if the pinholes and the thin concave portions 4a and 14a are formed in the formation stage of the conductive resin layers 4 and 14 by electrodeposition, By forming the corrosion-resistant resin layer 15 by electrodeposition, the fine recesses 4a and 14a are reliably filled, and the conductive resin layers 4 and 14 are covered with the corrosion-resistant resin layers 5 and 15. Thereafter, only the corrosion-resistant resin layers 5 and 15 covering both the front and back surfaces of the metal substrate are removed, and the flat surface from which the conductive resin layers 4 and 14 in which the fine recesses 4a and 14a are filled with the corrosion-resistant resin layers 5a and 15a are exposed. Is formed, and the corrosion-resistant resin layer 15 in other regions is left as it is as the corrosion-resistant resin layers 5b and 15b, so that a separator having excellent corrosion resistance can be manufactured.
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. 7 is a partial configuration diagram for explaining the structure of the polymer electrolyte fuel cell, and FIG. 8 is a diagram for explaining a membrane electrode assembly constituting the polymer electrolyte fuel cell. FIG. 10 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.
7 to 10, 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. 8, 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 are formed with the conductive resin layer 4 and the corrosion-resistant resin layers 5a and 5b as shown in FIG. 1, but are omitted in the illustrated example. ing.

  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 a polymer electrolyte fuel cell using the separator of the present invention will be described with reference to FIGS. 11 is a plan view for explaining the structure of the polymer electrolyte fuel cell, and FIG. 12 is a longitudinal sectional view taken along the 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. 11 and 12, 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. 11). 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.

As shown in FIG. 13, 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. 3, and have a conductive resin layer 14 and corrosion-resistant resin layers 15a and 15b 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.
<Formation of groove>
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-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 at a runout width of 50 mm and a pitch of 2 mm was obtained.

<Formation of conductive resin layer>
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.
Next, 75 parts by weight of carbon black (Vulcan XC-72 manufactured by Cabot Co., Ltd.) as a conductive material was added to and dispersed in the epoxy electrodeposition liquid with respect to 100 parts by weight of the resin solids to obtain an electrodeposition liquid.
The electrodeposition liquid 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. Then, it dried with hot air (150 degreeC, 3 minutes) with the dryer, and also heat-processed at 180 degreeC for 1 hour in nitrogen atmosphere. As a result, a conductive resin layer having a thickness of 20 μm was formed so as to cover the metal substrate. The melting temperature of the epoxy resin constituting this conductive resin layer was 160 ° C. Moreover, as a result of observing the surface of the formed conductive resin layer with a scanning electron microscope (SEM), the average number of fine concave portions (circular pinholes having a diameter of 10 to 100 μm or thin portions due to uneven thickness) was 10 / Mm ² was present.

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.

<Formation of corrosion-resistant resin layer>
Prepare an anti-corrosion electrodeposition paint (Electron KG400, manufactured by Kansai Paint Co., Ltd.), stir the anti-corrosion electrodeposition paint at 20 ° C., and immerse the metal substrate covered with the conductive resin layer in this Then, electrodeposition was performed at a gap of 700 mm and a voltage of 200 V for 60 seconds, and the pulled metal substrate was washed with pure water. Then, it dried with hot air (150 degreeC, 3 minutes) with the dryer, and also heat-processed for 140 minutes at 140 degreeC in nitrogen atmosphere. As a result, a corrosion-resistant resin layer having a thickness of 15 μm was formed so as to cover the conductive resin layer, and the fine recesses present in the conductive resin layer were completely filled with the corrosion-resistant resin layer. The melting temperature of the resin constituting this corrosion resistant resin layer was 130 ° C.

<Grinding of corrosion-resistant resin layer>
Of the corrosion-resistant resin layer formed as described above, only the region covering the conductive resin layer located on the front and back surfaces of the metal substrate is ground and removed using a buffing machine, and the conductive resin layer is exposed and flattened. A surface was formed. On the flat surface of the conductive resin layer formed in this way, the corrosion-resistant resin layer was filled in the fine recesses generated in the conductive resin layer. Moreover, the other area | region, ie, the area | region which coat | covers the groove part and the end surface of a metal substrate, was the state coat | covered with the corrosion-resistant resin layer. This obtained the separator.

As a result of measuring the electrical resistance of front and back conduction in the produced separator by the following method, it was 20 mΩ · cm ² , 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 certain period of time, the corrosion resistance is considered good.

[Example 2]
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 at a runout width of 50 mm and a pitch of 2 mm was obtained.

Next, pretreatment (passivation film removal) was performed on the above metal substrate using an aqueous nitric acid solution, followed by washing with water.
Next, a conductive resin layer was formed on the metal substrate in the same manner as in Example 1. As a result of observing the surface of the formed conductive resin layer in the same manner as in Example 1, the average number of fine concave portions (circular pinholes having a diameter of 10 to 100 μm or thin portions due to uneven thickness) was 15 / mm ^2. Existed at a rate of.
Next, in the same manner as in Example 1, a corrosion-resistant resin layer is formed so as to cover the conductive resin layer, and then the region of the corrosion-resistant resin layer that covers the conductive resin layers located on the front and back surfaces of the metal substrate. Only a buffing machine was used to grind and remove to obtain a separator.
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 17 mΩ · cm ² , 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 1]
A separator was produced in the same manner as in Example 1, except that the conductive resin layer was formed and the formation of the corrosion-resistant resin layer and grinding using a buffing machine were not performed.
As a result of measuring the electrical resistance of front and back conduction in the produced separator by the same method as in Example 1, it was 30 mΩ · cm ² , which was larger than that of the separator in Example 1.
Moreover, as a result of conducting a corrosion resistance test on the above-mentioned separator under the same conditions as in Example 1, red rust was generated after 600 hours, and the corrosion resistance was inferior to that of the separator in Example 1.

[Comparative Example 2]
A separator was produced in the same manner as in Example 2, except that the conductive resin layer was formed and the formation of the corrosion-resistant resin layer and grinding using a buffing machine were not performed.
The electrical resistance of front and back conduction in the produced separator was measured by the same method as in Example 1. As a result, it was 27 mΩ · cm ² , which was higher than that of the separator in Example 2.
Moreover, as a result of conducting a corrosion resistance test on the above-described separator under the same conditions as in Example 1, aluminum oxide was produced after 24 hours, and the corrosion resistance was inferior to that of the separator in Example 2.

[Comparative Example 3]
In the same manner as in Example 1, a metal substrate provided with 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 above 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. As a result, a conductive resin layer having a thickness of 40 μm was formed so as to cover the metal substrate, and a separator was obtained. The formed conductive resin layer is thicker than the conductive resin layer in Example 1. As a result of observing the surface of this conductive resin layer in the same manner as in Example 1, fine recesses (diameter of 10 to 10) were observed. 100 μm circular pinholes or thin portions due to uneven thickness) existed at an average rate of 30 / mm ² .

As a result of measuring the electrical resistance of conduction between the front and back surfaces of the separator thus produced by the same method as in Example 1, it was 40 mΩ · cm ² , which was larger than that of the separator in Example 1.
Moreover, about the said separator, as a result of performing a corrosion resistance test on the conditions similar to Example 1, red rust has generate | occur | produced in 1000 hours progress, and although the corrosion resistance is higher than the separator of the comparative example 1, the separator of Example 1 The corrosion resistance was inferior to that.

  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. FIG. 2 is an enlarged partial cross-sectional view of a portion surrounded by a chain line in FIG. 1. It is a fragmentary sectional view which shows other embodiment of the separator for fuel cells of this invention. FIG. 4 is an enlarged partial cross-sectional view of a portion surrounded by a chain line in FIG. 3. 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. 8 is a perspective view showing a state where the separator and the membrane electrode assembly of the polymer electrolyte fuel cell shown in FIG. 7 are separated from each other. FIG. 10 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. 7 are separated from a direction different from FIG. 9. 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 1,11 ... Separator 2,12 ... Metal substrate 3 ... Groove 4,14 ... Conductive resin layer 5, 5a, 5b, 15, 15a, 15b ... Corrosion-resistant resin layer 13 ... Through-hole 21, 51 ... Polymer electrolyte type fuel Battery 31, 61 ... Membrane electrode assembly (MEA)
41A, 41B, 41C, 71A, 71B ... separator

Claims (7)

  A metal substrate having a groove on at least one surface, and a conductive resin layer formed by electrodeposition so as to cover both the front and back surfaces of the metal substrate and the entire surface including the groove, of the conductive resin layer The area covering both the front and back surfaces of the metal substrate is formed by filling a fine recess formed in the conductive resin layer with a corrosion-resistant resin layer to form a flat surface, and the area of the conductive resin layer including the area covering the groove is formed. The other region is covered with a corrosion-resistant resin layer, the conductive resin layer contains a conductive material, and the corrosion-resistant resin layer is electrically insulating.   A metal substrate having a plurality of through-holes, and a conductive resin layer formed by electrodeposition so as to cover both the front and back surfaces of the metal substrate and the entire surface including the wall surface of the through-hole, Of these, the region covering both the front and back surfaces of the metal substrate is formed with a flat surface formed by filling a fine recess formed in the conductive resin layer with a corrosion-resistant resin layer, and includes the region covering the wall surface of the through hole. The other region of the conductive resin layer is covered with a corrosion-resistant resin layer, the conductive resin layer contains a conductive material, and the corrosion-resistant resin layer is electrically insulating. Separator.   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 as described.   The separator for a fuel cell according to any one of claims 1 to 3, wherein the conductive material is at least one of carbon particles, carbon nanotubes, carbon nanofibers, carbon nanohorns, and corrosion-resistant metals.   Using an electrodeposition liquid in which a conductive material is dispersed in a resin having electrodeposition properties, the surface of the metal substrate having a groove portion on at least one surface and the entire surface including the groove portion are coated so as to cover the entire surface including the groove portion. A step of forming a conductive resin layer by electrodeposition, a step of forming a corrosion-resistant resin layer by electrodeposition so as to cover the conductive resin layer using an electrically insulating and corrosion-resistant electrodeposition paint, and the corrosion resistance And a step of removing only the region covering the conductive resin layer located on both the front and back surfaces of the metal substrate from the resin layer to expose the conductive resin layer to form a flat surface. Manufacturing method of battery separator.   Using an electrodeposition liquid in which a conductive material is dispersed in a resin having electrodeposition properties, the front and back surfaces of the metal substrate having a plurality of through holes and the entire surface including the wall surfaces of the through holes are coated on the metal substrate. A step of forming a conductive resin layer by electrodeposition; a step of forming a corrosion-resistant resin layer by electrodeposition so as to cover the conductive resin layer using an electrically insulating and corrosion-resistant electrodeposition coating; and Removing only the region covering the conductive resin layer located on both front and back surfaces of the metal substrate of the corrosion-resistant resin layer to expose the conductive resin layer to form a flat surface. A method for producing a separator for a fuel cell.   The corrosion-resistant resin layer is formed by attaching a corrosion-resistant electrodeposition coating so as to cover the conductive resin layer by electrodeposition, and then heat-treating the corrosion-resistant electrodeposition coating. The manufacturing method of the separator for fuel cells of Claim 5 or Claim 6.

Images