KR101195104B1 - Production method for fuel cell separator, fuel cell separator, production method for fuel cell separator having gasket, and production method for fuel cell - Google Patents

Abstract

The present invention provides a method for producing a fuel cell separator that can provide high hydrophilicity to the surface, maintain the hydrophilicity for a long time, and maintain high power generation efficiency of the fuel cell. A molding composition containing a thermosetting resin containing an epoxy resin, a curing agent containing a phenolic compound, and graphite particles, and an equivalent ratio of the epoxy resin to the phenolic compound is in the range of 0.8 to 1.2. The surface of the obtained molded object 1 is subjected to a surface treatment including a wet blasting treatment and an atmospheric pressure plasma treatment of a remote method after the wet blasting treatment.

Description

TECHNICAL METHOD FOR FUEL CELL SEPARATOR, FUEL CELL SEPARATOR, PRODUCTION METHOD FOR FUEL CELL SEPARATOR HAVING GASKET, AND PRODUCTION METHOD FOR FUEL CELL}

The present invention relates to a method for manufacturing a fuel cell separator, a fuel cell separator, a method for producing a fuel cell separator having a gasket, and a method for producing a fuel cell.

In general, a fuel cell is composed of a cell stack configured by stacking several tens to hundreds of unit cells in series, thereby obtaining a predetermined voltage.

The most basic structure of a unit cell has a structure called "separator / fuel electrode (anode) / electrolyte / oxidant electrode (cathode / separator)". In this unit cell, fuel is supplied to a fuel electrode among a pair of electrodes facing each other with an electrolyte therebetween, and an oxidant is supplied to the oxidant electrode. By oxidizing the fuel by the electrochemical reaction, the chemical energy of the reaction is directly converted into electrochemical energy.

Such fuel cells are classified into several types according to the type of electrolyte. In recent years, attention has been paid to solid polymer fuel cells using a solid polymer electrolyte membrane as an electrolyte as a fuel cell capable of obtaining high output.

1 shows an example of a polymer electrolyte fuel cell. Between two fuel cell separators 20, 20 having a plurality of uneven parts lib, ribs, 21 on both left and right sides, an electrolyte 4, a solid polymer electrolyte membrane, and a gas diffusion electrode (fuel electrode 31 and A unit cell (unit cell) is interposed with a film-electrode composite (MEA) 5 composed of an oxidant electrode 32. A battery body (cell stack) is formed by arranging dozens to hundreds of such unit cells. In the fuel cell separator 20, a gas supply discharge groove 2, which is a flow path of hydrogen gas as a fuel or oxygen gas as an oxidant, is formed between adjacent uneven portions 21. As shown in FIG.

Such a cell stack is composed of, for example, 50 to 100 unit cells in the case of stationary home use, 400 to 500 unit cells in the case of vehicle loading, and 10 to 20 units in the case of mounting a notebook PC. It consists of unit cells.

Such a solid polymer fuel cell draws a current from an external circuit by supplying hydrogen gas to a fuel electrode and oxygen gas to an oxidant electrode, respectively. At this time, the reaction as shown in the following formula occurs in each electrode.

A fuel electrode ^{_{reaction: H 2 → 2H + + 2e}} - ... (One)

The oxidant electrode ^{reaction: 2H + + 2e _ + 1} / 2O 2 → H 2 O ... (2)

Total reaction: H ₂ + 1 / 2O ₂ → H ₂ O

That is, hydrogen (H ₂ ) on the fuel electrode becomes a proton (H ⁺ ), the proton moves inside the solid polymer electrolyte membrane to reach the oxidant electrode, reacts with oxygen (O ₂ ) on the oxidant electrode To produce (H ₂ O). Therefore, in the operation of the polymer electrolyte fuel cell, it is necessary to supply and discharge gas and draw current.

In addition, the polymer electrolyte fuel cell is typically assumed to operate under wet air in a range of room temperature or higher and 120 ° C or lower, and thus water is often treated in a liquid state. It is necessary to control the diffusion of and to discharge the liquid water from the oxidant electrode.

Moreover, in methanol direct fuel cell (DMFC) which is a kind of solid polymer fuel cell, methanol aqueous solution is used instead of hydrogen as a fuel. In this case, the reaction as shown in the following formula occurs in each electrode. In the oxidant electrode reaction, an oxygen reduction reaction (the same reaction as when hydrogen is used as a fuel) occurs.

A fuel electrode _{reaction: CH 3 OH + H 2 O} → CO 2 + 6H + + 6e - ... (One')

The oxidant electrode ^{_{reaction: 3 / 2O 2 + 6H +}} + 6e - → 3H 2 O ... (2')

Total reaction: CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O

Comparing the overall reactions of a methanol direct fuel cell (DMFC) with a conventional solid polymer fuel cell, the methanol direct fuel cell generates six times as much water, so it is better to discharge liquid water from the oxidant electrode. Becomes important.

Among the components constituting the fuel cell, the fuel cell separator 20 has a unique shape having a plurality of gas supply and discharge grooves 2 on one or both surfaces of the thin plate-like body, as shown in FIGS. 1A and 1B. The fuel cell separator 20 has a function of separating the fuel gas, the oxidant gas, and the coolant flowing through the fuel cell from mixing, and also transfers electric energy generated by the fuel cell to the outside, or heat generated from the fuel cell. It plays an important role in radiating heat to the outside.

In this solid polymer fuel cell, in order to prevent drying of the solid electrolyte, moisture must be frequently applied to the fuel gas and the oxidant gas, and water may be generated on the oxidant electrode side by the reaction. When these moistures adhere to the surfaces of the oxidant electrode side and the fuel electrode side of the separator 20, the gas supply and discharge grooves 2 are blocked, and the flow rate of oxygen gas or fuel gas is lowered, and the power generation efficiency is reduced. flooding) Therefore, there is an active discussion for discharging water adhering to the surface of the separator 20 efficiently.

For example, Patent Document 1 proposes to improve the wettability of the separator surface by irradiating the surface of the separator with vacuum ultraviolet light from the vacuum ultraviolet light irradiation device, but there is a problem that the productivity is insufficient and not suitable for practical use. have.

In Patent Document 2, it is proposed to form a hydrophilic phenol resin or a hydrophilic epoxy resin on the surface of the separator, and Patent Document 3 proposes to form a silane compound having a hydrophilic functional group. However, in the case of Patent Document 2, there is a possibility that the electrical characteristics of the separator may deteriorate. In the case of Patent Document 3, the process for forming the silane compound is complicated, and therefore, all of them are not suitable for practical use.

In patent document 4, although forming a separator from the molding material containing a silicon compound is proposed, there exists a problem that moldability falls.

In Patent Literature 5, the separator is first subjected to pretreatment in which it is heated in a heating furnace, and then the flame treatment of the burner is used to improve the hydrophilicity of the separator. However, hydrophilicity cannot be maintained for a long time.

In patent document 6, it is proposed to spray on the surface of a separator, burning a gas containing a silicon compound or the like. In this method, the treatment efficiency is high, and the separator surface after the treatment has high hydrophilicity. However, also in this method, the hydrophilicity of the separator surface deteriorates with time, and hydrophilicity cannot be sustained for a long time.

In patent document 7, although hydrophilic provision by hydrophilic gas is proposed, it cannot be said that it reached the practical level. Further, Patent Document 7 describes the use of fluorine gas as a hydrophilic gas, but a method for sufficiently improving the hydrophilicity of the surface of the separator and maintaining the hydrophilicity for a long time has not yet been found.

Although Patent Document 8 proposes an atmospheric pressure discharge plasma treatment of a fuel cell separator, there is a problem that the durability of the surface after the treatment is insufficient, and the hydrophilicity and drainage properties are markedly degraded over time.

In addition, Patent Document 9 proposes to prevent deterioration over time of hydrophilicity and wettability by roughening the separator surface and atmospheric pressure plasma treatment. However, the situation is a level that cannot be put into practical use, such as insufficient hydrophilicity in the gas supply and discharge grooves that are originally required.

As such, no effective means has yet been found to sufficiently improve the hydrophilicity of the separator surface and to maintain the hydrophilicity for a long time.

Patent Document 1: Japanese Patent Application Publication No. 2003-142116

Patent Document 2: Japanese Patent Application Laid-open No. 2000-251903

Patent Document 3: Japanese Patent Application Publication No. 2007-299754

Patent Document 4: Japanese Patent Application Publication No. 2008-186642

Patent Document 5: Japanese Patent Application Laid-Open No. 2002-313356

Patent Document 6: Japanese Patent Application Publication No. 2006-185729

Patent Document 7: International Publication No. WO99 / 40642

Patent Document 8: Japanese Patent Application Laid-Open No. 2002-25570

Patent Document 9: Japanese Patent Application Publication No. 2006-331673

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to provide high hydrophilicity to the surface of a fuel cell separator and to maintain the hydrophilicity for a long time, and to prevent the gas supply and discharge groove from being blocked by water droplets, thereby preventing the fuel cell from being blocked. It is an object of the present invention to provide a method for manufacturing a fuel cell separator capable of maintaining high power generation efficiency, a method for manufacturing a fuel cell separator, a method for manufacturing a fuel cell separator having a gasket, and a method for manufacturing a fuel cell.

MEANS TO SOLVE THE PROBLEM As a result of earnest research, in order to improve the hydrophilicity of a fuel cell separator, the present inventors discovered the method for maintaining the hydrophilicity of a fuel cell separator for a long time, and came to complete this invention.

In the manufacturing method of the 1st fuel cell separator which concerns on this invention, the thermosetting resin containing an epoxy resin, the hardening | curing agent containing a phenolic compound, and graphite particle are contained, The equivalence ratio of the said epoxy resin with respect to the said phenolic compound is 0.8. Molding composition for molding in the range of ~ 1.2. The surface of the obtained molded object is subjected to a surface treatment including a wet blast treatment and a remote atmospheric plasma treatment after the wet blast treatment.

Therefore, hydroxyl groups can be distributed on the surface of the molded body before the surface treatment by a very simple method of mixing the epoxy resin and the phenolic compound in the molding composition and adjusting the compounding ratio. By performing surface treatment on such a molded object surface, the hydrophilicity of the fuel cell separator surface is improved and such high hydrophilicity is maintained for a long time.

It is preferable that the said epoxy resin is cresol novolak-type epoxy resin, and the said phenol type compound is a novolak-type phenol resin.

In the manufacturing method of the 2nd fuel cell separator which concerns on this invention, the molding composition containing the thermosetting resin containing a thermosetting phenol resin, and graphite particle is shape | molded. The surface of the obtained molded object is subjected to a surface treatment including a wet blasting treatment and a remote atmospheric plasma treatment after such a wet blasting treatment.

Therefore, hydroxyl groups can be distributed on the surface of the molded body before the surface treatment by a very simple method of incorporating a thermosetting phenol resin in the molding composition. By performing the surface treatment on the surface of the molded body 1, the hydrophilicity of the fuel cell separator surface is improved and such high hydrophilicity is maintained for a long time.

In this invention, it is preferable to make arithmetic mean height Ra (JISB0601: 2001) of the surface of a molded object by a wet blasting process into 0.4-1.6 micrometers.

In this case, the treatment efficiency of the surface treatment for the molded body is increased, the hydrophilicity of the surface of the fuel cell separator is further improved, and the high hydrophilicity can be maintained for a long time.

It is preferable that the arithmetic mean height Ra of the surface of this molded object is further 1.2 micrometers or less. In this case, the hydrophilicity of the fuel cell separator can be further improved by the remote atmospheric plasma treatment, and the high hydrophilicity can be maintained for a long time, and the sealing of the surface of the fuel cell separator 20 can also be improved. have. Moreover, when this arithmetic mean height Ra is less than 1.0 micrometer, the sealing property of the fuel cell separator surface will further improve. In addition, when the arithmetic mean height Ra of the surface of a molded object is especially 0.6 micrometer or more, the hydrophilicity of a fuel cell separator further improves by a remote atmospheric plasma process.

In this invention, it is preferable that the plasma generation gas in the said atmospheric pressure plasma process is nitrogen gas whose oxygen gas content is 2000 ppm or less.

In this case, particularly high hydrophilicity is imparted to the fuel cell separator by the atmospheric pressure plasma treatment.

In this invention, it is preferable that the said composition for shaping | molding contains an internal mold release agent.

In this case, the uniform release property is exhibited during molding of the molding composition, and the external mold release agent is unnecessary at the time of molding, thereby improving the productivity of the molded body. In addition, the external release agent remaining unevenly distributed on the surface of the molded body can be removed, and this external release agent is prevented from adversely affecting the hydrophilicity of the surface of the molded body.

In the present invention, when heated under the conditions of a measurement start temperature of 30 ° C., a temperature rise rate of 10 ° C./min, a holding temperature of 120 ° C., and a holding time of 30 minutes at a holding temperature, the weight loss of the molding composition is 5% or less. On the other hand, it is preferable to contain the substituted imidazole which has a hydrocarbon group in 2nd position.

In this invention, it is also preferable that the said composition for shaping | molding contains triphenyl phosphine.

In the present invention, the surface treatment preferably includes a drying treatment. In this drying process, after the said wet blasting process and before atmospheric pressure plasma processing, the said molded object is dried to moisture absorption 0.1% or less.

In this case, it is possible to suppress that the atmospheric pressure plasma treatment of the molded body is inhibited by the water molecules and to improve the efficiency of the atmospheric pressure plasma treatment.

In the present invention, the surface treatment preferably includes a water contact treatment for bringing the surface of the molded body into contact with water after the atmospheric pressure plasma treatment. It is preferable that especially the said water is ion-exchange water or demineralized water.

In this case, the hydrophilicity of the surface of the molded body can be further improved.

In this invention, it is preferable to form the groove | channel for gas supply discharge | emission which the ratio (A / B) of width | variety A and depth B is 1 or more in the surface in which the molded object before the said surface treatment is performed. .

In this case, while forming the gas supply-discharge groove | channel which becomes a gas flow path on the surface of a molded object, the processing efficiency of the said surface treatment with respect to this molded object can be maintained high, and the hydrophilicity of the fuel cell separator surface is further improved and such high hydrophilicity is carried out. Can be maintained for a long time.

In this invention, it is preferable to make the contact resistance of the surface of the said molded object into 15 m (ohm) cm <^2> or less by the said surface treatment.

In this case, the hydrophilicity of the fuel cell separator can be improved, and the function of transferring the electrical energy generated in the fuel cell to the outside by the fuel cell separator can be maintained at a high level.

In this invention, it is preferable to make the static contact angle with the moisture of the surface of the said molded object into the 0-50 degree range by the said surface treatment.

In this case, the hydrophilicity of the fuel cell separator surface can be further improved.

In the present invention, the surface treatment may include a cleaning treatment for discharging the liquid toward the molded body while applying ultrasonic vibration to the liquid.

In the cleaning process, the frequency of the ultrasonic vibration applied to the liquid may be 900kHz.

In the cleaning treatment, the liquid may be alkaline ionized water.

A fuel cell separator according to the present invention is produced by the above method.

In the manufacturing method of the fuel cell separator with a gasket which concerns on this invention, after a gasket is laminated | stacked on the fuel cell separator manufactured by the said method, a atmospheric atmospheric plasma process of a remote system is performed to the surface of this fuel cell separator.

In the manufacturing method of the fuel cell separator which has a gasket which concerns on this invention, after laminating | stacking a gasket on the fuel cell separator manufactured by the said method, an ultrasonic vibration is applied to the liquid on the surface of this fuel cell separator, and this liquid is The cleaning process which discharges toward the said fuel cell separator can be applied.

In the fuel cell manufacturing method according to the present invention, a gasket is laminated on the fuel cell separator manufactured by the above method, and after the remote atmospheric plasma treatment is applied to the surface of the fuel cell separator, the fuel cell separator is removed. It is laminated with the membrane-electrode composite.

Therefore, volatile substances and hydrophobic substances caused by the gasket can be removed from the surface of the separator by atmospheric pressure plasma treatment, and the hydrophilicity of the separator can be further improved, thereby further improving the long-term durability of the fuel cell. .

According to the present invention, the hydrophilization treatment of the surface of the fuel cell separator can be performed at a high efficiency by a simple method, and the fuel cell separator hydrophilicity can be maintained for a long time. Therefore, it is possible to prevent the gas supply discharge groove of the fuel cell separator from being blocked by water droplets, so that the power generation efficiency of the fuel cell incorporating such a fuel cell separator can be maintained for a long time.

FIG. 1A is a schematic perspective view of a unit cell of a fuel cell, and FIG. 1B is a fuel cell separator of the unit cell.
2 is an exploded perspective view showing an example of a unit cell of a fuel cell constructed using a gasket.
3 is a perspective view showing an example of a fuel cell separator having a gasket;
4 is a perspective view showing an example of a fuel cell.
5 is a schematic view showing an example of a remote atmospheric plasma processing apparatus.
6 is a schematic view showing an example of a direct atmospheric atmospheric plasma processing apparatus.

The molding composition for producing the fuel cell separator 20 (hereinafter, referred to as the separator 20) contains a thermosetting resin and graphite particles as essential components.

It is preferable that the composition for shaping | molding does not contain a 1st amine and a 2nd amine. That is, the composition for the molding, it is preferred that the compound having a substituent -NH and -NH ₂ is not contained. Moreover, it is preferable not to contain a tertiary amine in the molding composition. Therefore, the separator 20 formed from such a molding composition does not contaminate the platinum catalyst in the fuel cell, so that the electromotive force drop when the fuel cell is used for a long time can be suppressed.

The thermosetting resin includes at least one of an epoxy resin and a thermosetting phenol resin as essential components. Epoxy resins and thermosetting phenolic resins are excellent in that they have a good melt viscosity and few impurities, and in particular, few ionic impurities.

It is preferable that content of the epoxy resin and the thermosetting phenol resin with respect to the thermosetting resin whole quantity exists in 50-100 mass% range. It is particularly preferable that the thermosetting resin contains only an epoxy resin, only a thermosetting phenol resin or only an epoxy resin and a thermosetting phenol resin.

It is preferable that an epoxy resin is solid form, and it is especially preferable that melting | fusing point is the range of 70-90 degreeC. Thereby, there is little change of material, and the handleability at the time of shaping | molding improves. If this melting | fusing point is less than 70 degreeC, aggregation will arise easily in the composition for shaping | molding, and there exists a possibility that the handleability of the composition for shaping | molding may deteriorate. In addition, if a low viscosity resin having a low melt viscosity is selected as the epoxy resin, the graphite composition can be filled in the molding composition and the separator 20 with high moldability while maintaining the moldability of the molding composition. In addition, a part of the epoxy resin may be in a liquid state within the range where the action is exerted.

Examples of the epoxy resin include ortho kresol novolac epoxy resins, bisphenol epoxy resins, biphenyl epoxy resins, and phenol aralkyl having a biphenylene structure. ) Epoxy resins are preferred. These resins are excellent in that they have a good melt viscosity and few impurities, in particular few ionic impurities.

In particular, it is preferable that an epoxy resin contains the epoxy resin component which consists only of an ortho cresol novolak-type epoxy resin. Or an epoxy resin comprising at least one epoxy resin component selected from an ortho cresol novolak type epoxy resin, a bisphenol type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl type epoxy resin having a biphenylene structure. It is preferable. When an ortho cresol novolak-type epoxy resin is made into an essential component, it becomes excellent in the moldability of the composition for shaping | molding, and also the heat resistance of the separator 20 becomes excellent. In addition, the manufacturing cost can be reduced. It is preferable that the ratio of the ortho cresol novolak-type epoxy resin in an epoxy resin component is 50-100 mass% range from a viewpoint of the said moldability improvement, the heat resistance improvement of the separator 20, and reduction of a manufacturing cost, Especially 50- It is preferably in the range of 70% by mass.

In order to further reduce the melt viscosity or to improve the toughness of the thin separator 20, it has a bisphenol-type epoxy resin, a biphenyl-type epoxy resin or a biphenylene structure together with an ortho cresol novolak-type epoxy resin. It is also preferable to use a phenol aralkyl type epoxy resin together.

When bisphenol F-type epoxy resin is used especially, the viscosity of the composition for shaping | molding can be reduced, and the composition for shaping | molding with especially moldability can be obtained. It is preferable that content of bisphenol F-type epoxy resin is 30-50 mass% in the epoxy resin component in this case.

Moreover, when a biphenyl type epoxy resin is used, since such a biphenyl type epoxy resin has low melt viscosity, the fluidity | liquidity of the composition for shaping | molding will improve remarkably, especially thin moldability will improve. It is preferable that content of a biphenyl type epoxy resin is 30-50 mass% in the epoxy resin component in this case.

Moreover, when the phenol aralkyl type epoxy resin which has a biphenylene structure is used, the intensity | strength and toughness of the separator 20 can be improved, and the hygroscopicity of the separator 20 can be reduced. Therefore, the mechanical properties of the separator 20, the conductivity, and the stability of the properties when used for a long time is excellent. It is preferable that the ratio of the phenol aralkyl type epoxy resin which has a biphenylene structure in the epoxy resin component in this case is 30-50 mass% range.

Moreover, it is preferable that content of the epoxy resin component with respect to the thermosetting resin whole quantity exists in 50-100 mass% range in the composition for shaping | molding.

The said epoxy resin component is contained in a composition for shaping | molding as at least one part of the epoxy resin in a thermosetting resin. That is, as other thermosetting resins other than the epoxy resin component, for example, epoxy resins other than the epoxy resin component, thermosetting phenol resins, vinyl ester resins, polyimide resins, unsaturated polyester resins, and diallyl It is also possible to use one or a plurality of resins selected from phthalate resins and the like. However, since the resin containing an ester bond may be hydrolyzed in an acid resistant environment, it is preferable not to use it. Moreover, it was also suitable to use polyimide resin from the point which contributes to the heat resistance and acid resistance improvement of the separator 20 as a thermosetting resin. As such a polyimide resin, it is particularly preferable to use a bismaleimide resin or the like. As such a bismaleimide resin, for example, 4,4-diamino diphenyl bismaleimide is used. Can be mentioned. By using this together, the heat resistance of the separator 20 can be improved more.

When using a thermosetting phenol resin, it is especially preferable to use the phenol resin to which a polymerization reaction advances by ring-opening polymerization. As such a phenol resin, a benzooxadine resin etc. are mentioned, for example. In this case, since no gas due to dehydration is generated in the molding step, voids are not generated in the molded article, and a decrease in gas permeability can be suppressed. It is also preferable to use a resol type phenol resin, for example, in 13 C-NMR analysis, ortho-ortho 25 to 35%, ortho-para 60 to 70 It is preferable to use a resol type phenolic resin having a structure of 5% to 10% by para-para. Although the resol resin is usually in a liquid state, the softening point of the resol-type phenol resin can be easily adjusted, so that the resol type phenol resin having a melting point of 70 to 90 ° C can be easily obtained. Thereby, the change of a material becomes small and the handleability of the composition for shaping | molding at the time of shaping | molding improves. If this melting | fusing point is less than 70 degreeC, aggregation will generate | occur | produce easily in the composition for shaping | molding, and there exists a possibility that handleability may deteriorate.

You may use together resin other than an epoxy resin and a thermosetting phenol resin. For example, one kind or plural kinds of resins selected from polyimide resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins and the like can be used. However, since the resin containing an ester bond may be hydrolyzed in an acid resistant environment, it is preferable not to use it.

Using a polyimide resin as the thermosetting resin is also suitable for improving the heat resistance and acid resistance of the separator 20. Especially as such a polyimide resin, it is preferable to use bismaleimide resin etc., As a specific example, 4, 4- diamino diphenyl bismaleimide is mentioned, for example. Thus, by using other resin together, the heat resistance of the separator 20 can be improved more.

When using an epoxy resin, the composition for shaping | molding makes a hardening | curing agent an essential component, and this hardening | curing agent makes a phenol type compound an essential component. As such a phenol type compound, a novolak-type phenol resin, a cresol novolak-type phenol resin, a multifunctional phenol resin, an aralkyl modified phenol resin, etc. are mentioned.

Content of a phenol type compound with respect to hardening | curing agent whole quantity is determined according to the usage-amount of an epoxy resin. It is especially preferable that a hardening | curing agent consists only of a phenolic compound.

Moreover, it is preferable that the total amount of content of a thermosetting resin and a hardening | curing agent in solid content of the composition for shaping | molding is the range of 14-24.1 mass%.

When using other hardening agents other than a phenol type compound together, it is preferable that another hardening agent is a non-amine type compound. In this case, the electrical conductivity of the separator 20 can be kept high, and the catalyst of the fuel cell can be prevented from being contaminated. It is also preferable not to use an acid anhydride type compound as a hardening | curing agent. When using an acid anhydride type compound, it may hydrolyze in an acidic environment, such as sulfuric acid, and may reduce the electrical conductivity of the separator 20, or may increase the elution of impurities from the separator 20.

When using an epoxy resin as a thermosetting resin, when mix | blending a thermosetting resin and a hardening | curing agent, the epoxy resin in a thermosetting resin and the phenolic compound in a hardening | curing agent have an equivalence ratio of the said epoxy resin with respect to the said phenolic compound of 0.8-1.2. It is preferable to make it into a range.

The graphite particles are used to reduce the electrical resistivity of the separator 20 and to improve the conductivity of the separator 20. It is preferable that content of graphite particle is 75-90 mass% with respect to the composition whole quantity for shaping | molding. When the content of the graphite particles is 75% by mass or more, the separator 20 may have sufficiently excellent conductivity. Moreover, when this content is 90 mass% or less, the molding composition will have sufficiently excellent moldability, and the separator 20 will have sufficiently excellent gas permeability.

The kind of graphite particles is not particularly limited as long as it is a kind having high conductivity. As graphite particles, for example, graphite particles obtained by graphitizing carbonaceous materials such as mesocarbon microbeads, graphite particles obtained by graphitizing coal-based coke or petroleum coke, processed powders of graphite electrodes or special carbon materials, natural Suitable ones, such as graphite, kishi graphite, expanded graphite, and the like can be used. Such a graphite particle can also use together multiple types besides the case of using only one type.

The graphite particles may be any of artificial graphite powder and natural graphite powder. Natural graphite powder has an advantage of high conductivity, and artificial graphite powder has a slightly lower conductivity than natural graphite powder, but has an advantage of low anisotropy.

The graphite particles are preferably purified even in the case of natural graphite powder or artificial graphite powder. In this case, since the content of ash and ionic impurities is low, the elution of impurities from the separator 20 as a molded product can be suppressed.

The ash content in the graphite particles is preferably 0.05% by mass or less. When ash content exceeds 0.05 mass%, there exists a possibility that the characteristic of the fuel cell manufactured using the separator 20 may fall.

It is preferable that the average particle diameter of graphite particle is the range of 15-100 micrometers. By this average particle diameter being 10 micrometers or more, the moldability of the composition for shaping | molding becomes excellent, and this average particle diameter becomes 100 micrometers or less, and the surface smoothness of the molded object 1 can be improved. In order to improve moldability further, it is preferable that the said average particle diameter is 30 micrometers or more. Moreover, in order to improve especially the surface smoothness of the molded object 1 and to make arithmetic mean height Ra (JISB0601: 2001) of the surface of the molded object 1 into the range of 0.4-1.6 micrometer as mentioned later, the said average particle diameter should be 70 micrometer or less. desirable.

In particular, in the case of obtaining the thin separator 20, the graphite particles preferably have a particle size that passes through a 100 mesh sieve (150 µm grid). When the graphite particles contain particles that do not pass through the 100 mesh sieve, the graphite particles having a large particle size are mixed in the molding composition, and thus the moldability of molding the molding composition into a thin sheet form is deteriorated.

The aspect ratio of the graphite particles is preferably 10 or less. In this case, it is possible to prevent anisotropy from occurring in the molded body 1 and to prevent deformation such as a bent state of the molded body 1.

And in correspondence with the anisotropy reduction of the molded object 1, the ratio of the contact resistance between the flow direction of the composition for shaping | molding at the time of shaping | molding in the molded object 1, and the direction orthogonal to this flow direction becomes 2 or less It is preferable.

As the graphite particles, it is particularly preferable to use graphite particles having two or more kinds of particle size distributions, that is, graphite particles obtained by mixing two or more kinds of particle groups having different average particle diameters. In this case, it is particularly preferable to mix graphite particles having an average particle diameter of 1 to 50 µm and graphite particles having an average particle diameter of 30 to 100 µm. When graphite particles having such a particle distribution are used, particles having a large particle size have a small surface area, so that kneading is possible even with a small amount of resin, and particles having a small particle size increase the contact between graphite particles, The strength of the molded article can be increased. Thereby, performance improvement, such as the improvement of the bulk density of the separator 20, the electroconductivity, the gas impermeability, the strength, etc. can be aimed at. The mixing ratio of the particles having an average particle diameter of 1 to 50 μm and the particle size of the average particle diameter of 30 to 100 μm may be appropriately adjusted, but especially the mixing mass ratio of the former to the latter is 40: 60 to 90: 10, especially 65:35 to 85:15. desirable.

The average particle diameter of the graphite particles is a volume average particle size measured by a laser diffraction scattering method using a laser diffraction scattering particle analyzer (Microtrack MT3000II series manufactured by Nikkiso Corporation).

Moreover, in the composition for shaping | molding, additives, such as a hardening catalyst (hardening accelerator), a wax (release agent), a coupling agent, can be contained as needed.

The molding composition may contain a suitable curing catalyst. However, in order not to contain a 1st amine and a 2nd amine in a shaping | molding composition, it is preferable to use a non-amine curing catalyst. For example, amine-based diamino diphenyl methan is not preferable because residues may contaminate the catalyst of the fuel cell. In addition, since imidazoles tend to easily release chlorine ions after curing, there is a fear of elution of impurities, which is not preferable.

However, when it heats on the conditions of 30 degreeC of measurement start temperature, 10 degreeC / min of temperature rise rate, 120 degreeC of holding temperature, and holding time in holding temperature, the weight reduction of the said composition for shaping | molding is 5% or less, and It is preferable to use the substituted imidazole which has a hydrocarbon group in 2nd position from the point which can improve the storage stability of the composition for shaping | molding. When obtaining the thin separator 20 especially, the volatility at the time of forming the sheet-like molded object 1 from the composition for shaping | molding prepared in the varnish shape, the smoothness of the said molded object 1, etc. become favorable. As such substituted imidazole, it is particularly preferred to use substituted imidazole having 6 to 17 carbon atoms in the hydrocarbon group at the 2nd position. Specific examples include 2-undecyl imidaxole, 2-heptadecyl imidazole, 2-phenyl imidazole, 1-benzyl-2-phenyl imidazole ), And the like. Of these, 2-undecyl imidazole and 2-heptadecyl imidazole are very suitable. These compounds may be used alone or in combination of two or more thereof. Molding hardening time can be adjusted by adjusting content of such substituted imidazole suitably. It is preferable that content of this substituted imidazole is 0.5-3 mass% with respect to the total amount of a thermosetting resin and a hardening | curing agent in the composition for shaping | molding.

It is also preferable to use a phosphorus compound as a curing catalyst. You may use together a phosphorus compound and the said substituted imidazole. Triphenyl phosphine is mentioned as an example of a phosphorus compound. When such a phosphorus compound is contained in the molding composition, elution of chlorine ions can be suppressed from the separator 20 that is a molded article.

The content of the curing catalyst in the molding composition can be adjusted appropriately, preferably in the range of 0.5 to 3 parts by mass with respect to the epoxy resin.

Suitable coupling agents may be used, but in order not to contain the first amine and the second amine in the molding composition, it is preferable that no amino silane is used. When amino silane is used, the catalyst of the fuel cell may be contaminated, which is not preferable. It is also preferable not to use mercapto silane as a coupling agent. Even when the mercapto silane is used, the catalyst of the fuel cell may be contaminated in the same manner.

As an example of a coupling agent, the coupling agent of a silicone type silane compound, a titanate type, and an aluminum type is mentioned. As a silicone coupling agent, epoxy silane is suitable.

When using an epoxy silane coupling agent, it is preferable that usage-amount is a range which content becomes 0.5-1.5 mass% in solid content of the composition for shaping | molding. Within this range, the coupling agent can be sufficiently suppressed to bleed on the surface of the separator 20.

The coupling agent may be previously attached to the surface of the graphite particles by spraying or the like. In this case, the addition amount of the coupling agent can be appropriately set in consideration of the specific surface area of the graphite particles and the coating area per unit mass of the coupling agent, and preferably, the total amount of the coupling agent coating area is based on the total amount of the graphite particle surface area, The range should be 0.5 ~ 2 times. Within this range, the coupling agent can be sufficiently suppressed from bleeding to the surface of the molded body 1 and the contamination of the mold surface can be suppressed.

Suitable waxes can be used as the wax (internal release agent), but internal mold release agents which are not synthesized with the thermosetting resin and the curing agent in the molding composition and separated from each other at 120 to 190 ° C are preferable. As such internal mold release agent, at least one selected from polyethylene wax, carnava wax, and a long chain fatty acid wax may be mentioned. Such internal mold release agents exhibit good release properties by being separated from the thermosetting resin and the curing agent in the molding process of the molding composition.

The content of the internal releasing agent in the molding composition may be appropriately set depending on the complexity of the shape of the separator 20, the depth of the groove, the ease of releasing with the mold surface such as the removal inclination, etc., but is 0.1 to 2.5 mass based on the total amount of the molding composition. It is preferably in the% range. Since this content is 0.1 mass% or more, sufficient mold release property can be exhibited at the time of mold shaping | molding, and since this content is 2.5 mass% or less, it is fully suppressed that the hydrophilicity of the separator 20 is impaired by wax. The content of this wax is more preferably in the range of 0.1 to 1% by mass, and more preferably in the range of 0.1 to 0.5% by mass.

When obtaining the thin separator 20 especially, a solvent can be contained in the composition for shaping | molding, and such a composition for shaping | molding can also be prepared in liquid form (including varnish shape and slurry state). As the solvent, for example, methyl ethyl ketone, methoxy propanol, N, N-dimethyl formamide, dimethyl sulfoxide, or the like Preference is given to using polar solvents. A solvent may use 2 or more types together besides using only one kind. The amount of the solvent used may be appropriately set in consideration of the moldability when the sheet-like molded body 1 is produced from the molding composition, but is preferably set so that the viscosity of the molding composition is in the range of 1000 to 5000 cps. And a solvent is used as needed, and if a composition for shaping | molding can be prepared in a liquid state by using liquid resin as a thermosetting resin, it is not necessary to use a solvent.

It is preferable to make content of the ionic impurity in the molded object 1 obtained from the resin composition for shaping | molding become sodium content 5 ppm or less and chlorine content 5 ppm or less by mass ratio with respect to the whole quantity of the molded object 1. For this purpose, it is preferable that content of the ionic impurity in shaping | molding composition is 5 ppm or less of sodium content and 5 ppm or less of chlorine content by mass ratio with respect to the whole composition for shaping | molding. In this case, elution of the ionic impurities from the separator 20 can be suppressed, and deterioration of characteristics such as lowering of the starting voltage of the fuel cell due to elution of the impurities can be suppressed.

In order to reduce content of the ionic impurity of the molded object 1 and the composition for shaping | molding as mentioned above, each ionic composition which the thermosetting resin, hardening | curing agent, graphite, other additives, etc. which comprise a composition for shaping | molding contain as each component. It is preferable to use components whose content of impurities is 5 ppm or less of sodium content and 5 ppm or less of chlorine content with respect to each component by mass ratio.

The content of the ionic impurities is derived depending on the amount of the ionic impurities in the extract of the object. The extract water is obtained by adding the object in ion exchange water at a rate such that the amount of ion exchange water becomes 100 ml with respect to 10 g of the object, and heating it at 90 ° C. for 50 hours. The content of ionic impurities in the extract water is evaluated by ion chromatography. Thereby, according to the amount of ionic impurities in the extracted water, the amount of ionic impurities in the object can be derived in terms of mass ratio with respect to the object.

It is preferable that the composition for shaping | molding is prepared so that TOC (totalorganic carbon) of the molded object 1 formed from such a molding composition may be 100 ppm or less.

TOC is a numerical value measured using the aqueous solution obtained by inject | pouring a molded object in ion-exchange water at the ratio which makes ion-exchange water 100 ml with respect to 10 g of molded objects, and processing at 90 degreeC for 50 hours. Such TOC can be measured, for example using the all-organic carbon analyzer "TOC-50" manufactured by Shimadzu Corporation in accordance with JISK0102. In the measurement, the CO ₂ concentration generated by the combustion of the sample is measured by a non-dispersive infrared gas analysis method to quantify the carbon concentration in the sample. By measuring the carbon concentration, the organic substance concentration can be measured indirectly. Inorganic carbon (IC) and all carbon (TC) in the sample are measured, and total organic carbon (TOC) is measured from the difference between all carbon and inorganic carbon (TC-IC).

By making said TOC 100 ppm or less, the fall of the characteristic as a fuel cell can further be suppressed.

The value of TOC can be reduced by selecting a component of high purity as each component which comprises the composition for shaping | molding, adjusting the equivalence ratio of resin, or performing a post-cure process at the time of shaping | molding.

The molding composition is prepared by mixing the above components by a suitable method and kneading and assembling as necessary.

This molding composition can be molded to obtain a molded body 1 to be the separator 20. As the molding method, a suitable method such as injection molding or compression molding can be used. In the separator 20, for example, as shown in FIG. 1, a plurality of uneven parts (ribs, 21) are formed on both surfaces, so that hydrogen gas, which is a fuel, and oxygen, which is an oxidant, are formed between adjacent uneven parts 21. A gas supply discharge groove 2, which is a flow path of gas, is formed.

The separator 20 has an anode side separator having a gas supply and discharge groove 2 only on one surface thereof, and a cathode side separator having a gas supply and discharge groove 2 only on one side opposite to the anode side separator. It can be configured as. By superimposing such an anode side separator and a cathode side separator, the separator 20 which has the gas supply discharge groove | channel 2 on both surfaces as shown in FIG. 1 is comprised. A flow path through which cooling water flows may be formed between the anode side separator and the cathode side separator. In this case, it is preferable to interpose a gasket between the anode side separator and the cathode side separator.

When the thin separator 20 is obtained from the molding composition prepared in the liquid phase, first, the molding composition is molded into a sheet to form a fuel cell separator molding sheet (molding sheet). The molding composition is molded into a sheet by, for example, casting. In this case, various kinds of film thickness adjusting means may be used. In this way, the casting method using various kinds of film thickness adjusting means can be realized by, for example, using a multi-cotter that has already been put to practical use. As the film thickness adjusting means, it is preferable to use at least one of the doctor knife and the wire bar, that is, either or both together with a slit die. It is preferable that it is 0.05 mm or more, and, as for the thickness of this molding sheet, it is more preferable if it is 0.1 mm or more. Moreover, it is preferable that especially this thickness is 0.5 mm or less, and it is more preferable if it is 0.3 mm or less. By reducing the thickness of the molding sheet to 0.5 mm or less in this manner, the thickness of the separator 1 can be reduced or reduced, and the cost can be reduced. In particular, when the thickness is 0.3 mm or less, the molding sheet can be used in the case of using a solvent. It can effectively suppress that a solvent remains inside. Moreover, when this thickness is less than 0.05 mm, since the advantage necessary for manufacture of the separator 20 is not fully exhibited, it is preferable that this thickness is 0.1 mm or more especially especially in consideration of moldability.

The sheet for molding is dried by casting to form a semi-cured (B stage) state, which is subjected to compression or thermosetting molding to form a plurality of uneven portions (ribs, 21) on both sides thereof. A gas supply discharge groove 2 is formed between the portions (ribs) 21. Thereby, the molded object 1 can be obtained. At this time, by forming the molded body 1 in the form of a wave plate, the gas supply discharge groove 2 on the other side can be formed on the back side of the one side side uneven portion 21. In this case, although it is formed in a thin shape, it is possible to obtain a molded body 1 having a plurality of uneven parts (ribs, 21) on both sides, and having a gas supply and discharge groove 2 between the uneven parts (ribs, 21). .

At the time of compression and thermosetting of this molding sheet, the molding sheet is first cut or perforated to a predetermined planar dimension as necessary, and then thermally cured with a compression molding machine in the mold. The compression and thermosetting molding requirements may depend on the composition of the molding composition, the kind of the conductive base material, the molding thickness, and the like. desirable.

In manufacture of the molded object 1, the molded object 1 can be manufactured by shape | molding one sheet | seat for shaping | molding, and forming the molded object 1, or forming a plurality of sheets for shaping | molding.

By molding the molding sheet in this way, the thin molded body 1, in particular, the separator 20 having a thickness in the range of 0.2 to 1.0 mm can be produced. By using the sheet for molding, even when the thin separator 20 is manufactured, the molding material is thinly and uniformly arranged to be molded and the moldability and thickness precision are increased.

And at the time of manufacture of the molded object 1, you may laminate | stack a shaping | molding sheet and a suitable electroconductive base material. By using a conductive base material, the mechanical strength of the separator 20 can be improved. When using a conductive base material, compression and thermosetting molding can be carried out in the state which laminated | stacked the sheet | seat for shaping | molding (including lamination | stacking several shaping | molding sheets | sheets) on both sides of a conductive base material, or the sheet | seat for shaping | molding ( Compression and thermosetting molding can be performed in a state in which conductive base materials are laminated on both sides of a plurality of sheets for forming).

As said conductive base material, carbon paper, carbon prepreg, carbon felt, etc. can be illustrated, for example. Moreover, these electroconductive base materials may also contain base material components, such as glass and resin, in the range which does not impair electroconductivity. The range of 0.03-0.5 mm is preferable, and, as for the thickness of an electroconductive base material, the range of 0.05-0.2 mm is more preferable.

In the molded body 1 thus formed, when using a thermosetting resin containing an epoxy resin and a curing agent containing a phenolic compound, the hydroxyl groups generated in the cured product are distributed on the surface of the molded body 1. do. In particular, the equivalent ratio of the epoxy resin to the phenolic compound is 0.8 to 1.2, so that the hydrophilicity of the molded body 1 can be greatly improved by surface treatment of the molded body 1 as described later, and the hydrophilicity can be maintained for a long time. do. If this equivalence ratio is larger than 1.2, the above effects cannot be obtained, which is considered to be because the hydroxyl groups distributed in the molded body 1 are insufficient. Moreover, even if this equivalence ratio is less than 0.8, the reason is unclear, but the effect as mentioned above cannot be acquired. In order to make the effect by surface treatment remarkable, it is especially preferable that the said equivalence ratio is 0.8-1.0. In this case, since the equivalent amount of hydroxyl groups is excessive, many hydroxyl groups can be distributed on the surface of the molded body 1. More preferably, the equivalent ratio is in the range of 0.8 to 0.9.

Moreover, even when using the thermosetting resin containing a thermosetting phenol resin, the hydroxyl group resulting from the thermosetting phenol resin in the molded object 1 will distribute on the surface of the molded object 1. As shown in FIG. Thereby, the effect of improving hydrophilicity by the surface treatment with respect to the molded object 1 can be acquired as mentioned later.

Next, the surface of the molded body 1 is subjected to a surface treatment including a wet blast treatment as shown and an atmospheric pressure plasma treatment in a remote system. Such surface treatment is performed at least on the surface in which the gas supply discharge groove 2 is formed in the molded object 1.

In the wet blasting process, the slurry prepared by dispersing an abrasive in a liquid such as water is sprayed onto the surface of the molded body 1, thereby removing the skin layer of the surface layer of the molded body 1, and at the same time, the surface roughness of the molded body 1 Adjust it. In the wet blasting process, no dust scattering is generated, so that the treatment area can be enlarged, the treatment efficiency is increased, and the treatment using a fine abrasive can also be performed. Therefore, the surface roughness of the molded body 1 can be easily adjusted to a desired range.

It is preferable to make arithmetic mean height Ra (JISB0601: 2001) of the surface of the molded object 1 into 0.4-1.6 micrometers through this wet blasting process. In this case, the uniformity of the surface treatment is further increased, and the hydrophilicity of the surface of the separator 20 can be further improved. Moreover, by making the surface roughness of this molded object 1 into the said range, the gas leak in the junction part of the separator 20 and the gasket 12 obtained from this molded object 1 can also be suppressed. Therefore, it is not necessary to mask the site | part which joins with the gasket 12 in the molded object 1 at the time of a wet blasting process, and the production efficiency of the separator 20 improves. And it is difficult to make said arithmetic mean height Ra less than 0.4 micrometer, and when this value is larger than 1.6 micrometer, there exists a possibility that the said gas leak may not be fully suppressed. If the arithmetic mean height Ra of the surface of this molded object 1 is especially 1.2 micrometers or less, the hydrophilicity of the surface of the separator 20 can be improved further. Moreover, when the arithmetic mean height Ra of the surface of this molded object 1 is less than 1.0 micrometer, the said gas leak is further suppressed. In this case, even if the clamping force at the time of manufacturing a cell stack is reduced with the thinning of the separator 20, the said gas leak can fully be suppressed. If the arithmetic mean height Ra of the surface of the molded object 1 is especially 0.6 micrometer or more, the hydrophilicity of the surface of the separator 20 can be improved further.

Moreover, the molded object 1 after a wet blasting process can also be wash | cleaned using ion-exchange water etc. as needed.

It is preferable to dry the molded object 1 by performing a drying process on the molded object 1 after this wet blasting process before atmospheric pressure plasma processing. In this drying process, it is preferable to air-dry the molded body 1 using an air blow or the like. In this case, air blow by normal temperature or warm air may be performed as needed, or air blow by warm air may be additionally performed after air blow at normal temperature. In addition, in the drying process, the molded body 1 is left to stand in a desiccator containing a drying agent such as silica gel, and the molded body 1 is left to stand in a drier set at a temperature of room temperature or more (for example, 50 ° C). You may use the method, the method of removing moisture from the molded object 1, etc. using a vacuum dryer. By such a drying process, it is preferable to dry the molded object 1 until the moisture absorption rate becomes 0.1% or less.

Next, the atmospheric pressure plasma process of a remote system is performed to the surface of this molded object 1. The remote atmospheric plasma treatment is a process of ejecting a gas stream containing plasma toward the molded body 1 under atmospheric pressure or under atmospheric pressure close to the atmospheric pressure. In this remote atmospheric plasma processing, for example, as shown in FIG. 5, the discharge space 10 having the tuyeres 9 and the discharge electrodes 6 and 6 for generating an electric field in the discharge space 10. Is used. In this plasma processing apparatus, the plasma generating gas 7 is supplied to the discharge space 10, and the pressure in the discharge space 10 is maintained at an atmospheric pressure close to the atmospheric pressure, and the discharge electrodes 6 and 6 are provided. ), A discharge is generated in the discharge space 10 to generate a plasma in the discharge space 10. Plasma processing can be performed by blowing the gas stream 8 containing this plasma from the tuyeres 9 and blowing into the molded object 1. As such a plasma processing apparatus, although the APT series manufactured by Sekisui Chemical Co., Ltd. is mentioned, for example, the appropriate plasma processing apparatus manufactured by Panasonic Electric Co., Ltd., Yamato Material Co., Ltd. can also be used. have.

By employing such a remote method, plasma can be injected toward the surface of the molded body 1, and it can be sufficiently processed to the inner surface of the gas supply and discharge groove 2 of the molded body 1. In addition, since the molded body 1 is not exposed to the discharge during the plasma treatment, the molded body 1 can be prevented from being damaged during the plasma treatment.

In addition to the remote method, the plasma generating gas 7 is supplied to the periphery of the processing object 11 as shown in FIG. 6 in addition to the remote method, and the discharge electrode 6 is supplied to the periphery of the processing object 11. And 6), there is also a direct method for generating plasma by discharging the battery. However, when the molded body 1 is treated in a direct manner, since the molded body 1 is conductive, minute damage occurs to the molded body 1 due to discharge, and further, the inner surface of the gas supply discharge groove 2 is sufficiently treated. It is difficult to do so, which is undesirable.

The remote atmospheric plasma treatment can be performed under conditions appropriately set to impart desired hydrophilicity to the surface of the molded body 1. It is preferable that the gas for plasma generation 7 in this atmospheric pressure plasma process is nitrogen gas, and it is preferable that especially the oxygen content in this nitrogen gas is 2000 ppm or less. In this case, especially high hydrophilicity is provided to the separator 20 by atmospheric pressure plasma processing.

Moreover, it is preferable to perform this atmospheric pressure plasma process on the conditions where the temperature of the molded object 1 and the temperature of the atmosphere were adjusted so that condensation might not generate | occur | produce on the surface of the molded object 1. In this case, the plasma is prevented from being consumed by the water droplets attached to the surface of the molded body 1, and the processing efficiency can be improved. It is preferable that the temperature of the molded object 1 is more than the temperature (dew point temperature) which prevents dew condensation on the surface of this molded object 1 as mentioned above, and is 70 degrees C or less for stable atmospheric pressure plasma processing. For stable atmospheric pressure plasma treatment, it is also important to keep the temperature of the molded body 1 and the temperature of the atmosphere constant. In the adjustment of the atmospheric temperature, the temperature of the plasma unit portion of the plasma processing apparatus is usually adjusted, and the temperature of the pedestal supporting the molded body 1 during the plasma processing is adjusted depending on the configuration of the plasma processing apparatus.

The molded body 1 after the atmospheric plasma treatment may be left in the air as it is, but the surface of the molded body 1 is brought into contact with water through a treatment such as immersing the molded body 1 in water such as ion-exchanged water. It is preferable to carry out the water contact treatment to make it.

In this manner, when the surface treatment including wet blasting and remote atmospheric plasma treatment is performed on the surface where hydroxyl groups are distributed in the molded body 1, the hydrophilicity of the surface of the molded body 1 is improved and such high hydrophilicity is achieved. This can be maintained for a long time. Although the details of this hydrophilization mechanism are not clear, the hydroxyl groups are distributed on the surface of the molded body 1, so that moisture is adsorbed on the surface, so that functional groups are easily generated, and by the atmospheric pressure plasma treatment, Contaminants are removed from the surface to form a high activity, and hydrophilic functional groups such as hydroxyl groups are introduced to the activated surface to form a large number of hydrophilic functional groups on the surface of the molded body 1, which contributes to the improvement of hydrophilicity. I think.

In addition, in the case of surface treatment, when the molded body 1 is subjected to the above-described drying treatment, it is suppressed that the atmospheric pressure plasma treatment to the molded body 1 is inhibited by the water molecules, and the efficiency of the atmospheric pressure plasma treatment is reduced. Is improved.

Moreover, in such a surface treatment, when the molded object 1 after atmospheric pressure plasma treatment is subjected to the above water contact treatment, the hydrophilicity of the surface of the molded body 1 is further improved. Although the detailed mechanism is not clear, it is thought that the hydrophilicity of the surface of the molded object 1 improves because water molecules adsorb | suck to the surface of the molded object 1 activated by atmospheric pressure plasma processing.

Surface treatment may also include a washing process. This cleaning process removes impurities such as various inorganic substances, organic substances, metal ions, and the like that cause performance deterioration of the fuel cell from the surface of the molded body 1. For example, the cleaning treatment is performed on the molded body 1 after the wet blasting treatment and before the remote atmospheric plasma treatment. In this case, the impurities adhering to the molded body 1 by the wet blast treatment are sufficiently removed by the washing treatment. It is preferable that the said drying process is given to the molded object 1 after a washing | cleaning process and before a atmospheric pressure plasma process of a remote system.

In the cleaning process, first, ultrasonic vibration is applied to the liquid, so that the liquid is discharged toward the molded body 1. For example, ultrasonic vibration is applied to this liquid in the container to which the liquid is supplied, and the liquid is discharged from the container toward the molded body 1. The molded body 1 is cleaned by such a method, so that damage to the molded body 1 is suppressed and defects such as graphite particles dropping out of the molded body 1 are suppressed, while the molded body 1 is sufficiently cleaned and the molded body 1 Impurities are removed from the surface.

Water is mentioned as a liquid used by a washing process. This liquid may be a liquid mixture of water and a hydrophilic organic solvent such as ethanol. Especially as water, it is preferable to use demineralized water, ion-exchange water, RO water (water processed by the reverse osmosis membrane), or ozone water. When ozone water having an ozone concentration of 50 ppm or more is used, the hydrophilicity of the surface of the separator 20 is further improved, and the contact resistance of the surface of the separator 20 is reduced. It is more preferable if this ozone concentration is 80 ppm or more. The upper limit of the concentration of ozone water is not particularly limited, but the practical upper limit is 110 ppm.

It is also preferable that the liquid used by the washing process is alkaline ionized water. In this case, impurities are removed from the molded body 1 with higher efficiency.

The dimension between the nozzle for discharging liquid from the container and the molded body 1 is adjusted in the range of 2-20 mm, for example. It is preferable that the frequency of the ultrasonic vibration applied to a liquid is 900 kHz or more, for example, the range of 900-1000 kHz is preferable. In addition, the output of the ultrasonic vibration applied to the liquid is preferably in the range of 100 ~ 650W. Under such conditions, damage to the molded body 1 is further suppressed.

In order to sufficiently remove impurities from the molded body 1 and to suppress damage to the molded body 1, the processing time of the molded body 1 is preferably adjusted appropriately according to the output of the ultrasonic vibration applied to the liquid. For example, with an output of 100-600W, the processing time is adjusted to a range of 0.2-3 minutes. In the continuous processing in which the liquid is discharged to the molded body 1 while the molded body 1 is continuously conveyed, ultrasonic vibration is applied to the liquid while the conveying speed of the molded body 1 is adjusted to a range of 5 to 20 mm / sec. It is desirable that the output of is adjusted to a range of 100 to 650 W.

It is preferable that ratio (A / B) of the width | variety A and the depth B of the gas supply discharge groove 2 formed in the surface in which the molded object 1 is surface-treated is one or more. In this case, the gas stream 8 including the slurry during the wet blast treatment at the time of surface treatment and the plasma at the atmospheric pressure plasma treatment tends to be widely spread inside the gas supply and discharge grooves 2. As a result, the uniformity of the surface treatment is further increased, so that the inner surface of the gas supply and discharge groove 2 can be sufficiently hydrophilized. Although the upper limit of the said ratio A / B is not restrict | limited, In order to form the gas supply discharge groove 2 at high density, it is preferable that it is 10 or less in actual use.

By surface treatment, it is preferable to make it the static contact angle with the water of the surface of the molded object 1 after a process becomes the 0-50 degree range. This static contact angle is particularly preferably in the range of 0 to 10 °, and more preferably in the range of 0 to 5 °. The static contact angle with this water can be adjusted by setting surface treatment conditions suitably. Thereby, the surface of the molded object 1 can have sufficiently high hydrophilicity.

It is preferable to make the contact resistance of the said surface-treated surface of the molded object 1 into 15 m (ohm) cm <^2> or less by surface treatment. This contact resistance can also be adjusted by setting surface treatment conditions suitably. Thereby, the function of the separator 20 which delivers the electric energy which generate | occur | produced to the fuel cell to the outside can be maintained at a high level.

The fuel cell can be manufactured using the separator 20 manufactured as mentioned above. 1 shows an example of a polymer electrolyte fuel cell, and includes an electrolyte 4 such as a solid polymer electrolyte membrane and a gas diffusion electrode (fuel electrode 31 and an oxidant electrode) between two separators 20 and 20. 32)) to form a unit cell (unit cell) via a film-electrode composite (MEA) 5 composed of the same. Dozens to hundreds of these unit cells can be arranged in parallel to form a battery body (cell stack).

2 shows an example of the structure of a unit cell of a solar cell constructed using the gasket 12. This unit cell is comprised by overlapping the separators 20 and 20, the gaskets 12 and 12, and the membrane-electrode composite 5. In the separator 20, the first fuel through holes 131 and 131 and the first oxidant through holes are formed in the outer circumferential portion surrounding the region where the uneven portion 21 and the gas supply discharge groove 2 are formed. 132 and 132 are formed. Two first fuel through holes 131 and 131 are formed, and each of the first fuel through holes 131 and 131 is a fuel electrode 31 of the separator 20. Are in communication with both ends of the gas supply and discharge groove 2 on the surface overlapping with each other. Two first oxidant through holes 132 and 132 are also formed, and each of the first oxidant through holes 132 and 132 is for discharging the gas supply at a surface overlapping with the oxidant electrode 32 of the separator 20. Both ends of the grooves 2 communicate with each other. Moreover, the 1st cooling through-hole 133 is also formed in this outer peripheral part.

On the outer circumferential portion of the separator 20, a gasket 12 for sealing is laminated. The gasket 12 includes an opening 15 for receiving a fuel electrode 31 or an oxidant electrode 32 of the membrane-electrode composite 5 at approximately the center, and the separator 20 at the opening 15. Gas supply discharge grooves 2 are exposed. On the outer circumferential side of the opening 15, the second fuel is positioned at a position where the first fuel through hole 131, the first oxidant through hole 132, and the first cooling through hole 133 of the separator coincide with each other. The through holes 141, the second oxidant through holes 142, and the second cooling through holes 143 are formed, respectively.

In addition, the outer periphery of the electrolyte 4 of the membrane-electrode composite 5 also includes the first fuel through hole 131, the first oxidant through hole 132, and the first cooling through hole 133 of the separator. ), The third fuel through hole 161, the third oxidant through hole 162, and the third cooling through hole 163 are formed at positions where () coincide with each other.

In such a unit cell structure, the separator 20, the gasket 12, and the first fuel through hole 131, the second fuel through hole 141, and the third fuel through hole 161 of the electrolyte 4. ), The fuel passage for supplying and discharging fuel to the fuel electrode is formed. In addition, the first oxidant through-hole 132, the second oxidant through-hole 142, and the third oxidant through-hole 162 communicate with each other, so that an oxidant flow path for supplying and discharging the oxidant to the oxidant electrode is provided. It is composed. Moreover, the 1st cooling through hole 133, the 2nd cooling through hole 143, and the 3rd cooling through hole 163 communicate, and the cooling flow path through which cooling water etc. flows is comprised.

In the unit cell structure of such a fuel cell, the fuel electrode 31, the oxidant electrode 32, and the electrolyte 4 are formed of a known material corresponding to the type of fuel cell. In the case of a solid polymer fuel cell, the fuel electrode 31 and the oxidant electrode 32 are formed by supporting a catalyst on a base material such as carbon cross, carbon paper, carbon felt, or the like. As a catalyst of the fuel electrode 31, a platinum catalyst, a platinum ruthenium catalyst, a cobalt catalyst, etc. are mentioned, for example, A platinum catalyst, a silver catalyst, etc. are mentioned as a catalyst of the oxidant electrode 32. As shown in FIG. In the case of a solid polymer fuel cell, the electrolyte 4 is formed of, for example, a proton conductive polymer membrane, and particularly in the case of a methanol directly fuel cell, for example, the proton conductivity is high, and the electron conductivity and the methanol permeability are high. It is formed of a fluorine resin or the like which hardly represents.

In addition, the gasket 12 is, for example, natural rubber, silicone rubber, SIS copolymer, SBS copolymer, SEBS, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber, It is formed of a rubber material selected from hydrogenated acrylonitrile-butadiene rubber (HNBR), chloroprene rubber, acrylic rubber, fluorine rubber and the like. A tackifier may be mix | blended with this rubber material. Among these rubber materials, ethylene-propylene-diene rubber (EPDM) is preferably used in terms of cost reduction, and fluororubber (FKM) is preferably used in view of improving durability of the gasket 12.

4 shows an example of a fuel cell C (cell stack) composed of a plurality of unit cells. The fuel cell C communicates with the fuel supply port 171 and the discharge port 172 and the oxidant supply port 181 and the discharge port 182 communicated with the oxidant flow path and the cooling flow path. Cooling water supply port 191 and the discharge port (192).

Since the fuel cell C is provided with hydrophilicity on the surface of the separator 20, it is difficult for the gas supply and discharge grooves 2 of the separator 20 to be blocked by water droplets, and the power generation efficiency of the fuel cell is lowered. Can be suppressed. In addition, since the hydrophilicity of the separator 20 can be maintained for a long time, the power generation efficiency of the fuel cell can be maintained high for a long time.

However, in this embodiment, as shown in FIG. 2, the separator 20 is provided with the groove | channel 2 for gas supply discharge | emission of a straight type. Generally, as the gas supply discharge | emission groove | channel 2 of the separator 20, there exists a serpentine type groove | channel with a curvature, and the straight type groove | channel with no curvature. When gas flows into the gas supply discharge groove 2 of the separator 20, the gas flow rate may become nonuniform inside the gas supply discharge groove 2. In the case of the sand groove, the nonuniformity of the gas flow rate can be alleviated by a design such as reducing the number of the grooves downstream of the gas supply and discharge groove 2, but in the case of the straight type, the nonuniformity of the gas flow rate is eliminated. It is difficult. Due to the nonuniformity of the gas flow rate, a portion having a small gas flow rate is formed in the gas supply discharge groove 2, and when water droplets adhere to this portion, it is difficult to discharge the water droplet from the gas supply discharge groove 2. However, even when the gas flow rate becomes uneven inside the gas supply discharge groove 2 in this way, in the present embodiment, the hydrophilicity of the surface of the separator 20 is improved, so that the gas supply discharge groove 2 Discharge of moisture is promoted to prevent the gas supply discharge groove from being blocked by water droplets. Of course, the sand-shaped gas supply discharge | emission groove | channel 2 can also be formed in the separator 20 shown in FIG.

In the manufacture of the fuel cell, after the gasket 12 is laminated on the separator 20, the atmospheric pressure plasma treatment in the remote room is applied to the surface where the gas supply and discharge grooves 2 of the separator 20 are formed. It is preferable to carry out. In this case, a fuel cell separator 30 having a gasket as shown in FIG. 3 can be obtained. The unit cell structure can be configured by stacking the fuel cell separator 30 having this gasket into the membrane-electrode composite 5.

For example, the gasket 12 can be laminated on the separator 20 by joining the gasket 12 formed in a sheet or plate shape in advance by bonding or fusion to the separator 20. The gasket 12 may be laminated on the separator 20 by molding a material for forming the gasket 12 on the surface of the separator 20. As a material used for formation of the gasket 12, a non-vulcanized rubber material is mentioned. By applying such a non-vulcanized rubber material to a predetermined position on the surface of the separator 20 by screen printing or the like, and vulcanizing the coating film of such rubber material, a gasket 12 having a desired shape is placed at a predetermined position on the surface of the separator 20. Can be formed. In connection with the vulcanization, a heating, irradiation of radiation such as an electron beam, or other suitable vulcanization method is used. In this case, even in the thin separator 20, the gasket 12 can be laminated easily. In addition, the separator 20 is installed in a mold, and the vulcanized rubber material is injected to a predetermined position on the surface of the separator 20 and vulcanized by a method of heating the rubber material, for example, on the surface of the separator 20. The gasket 12 of a desired shape may be formed at a predetermined position. As described above, in forming the gasket 12 by mold molding, in addition to transfer molding, compression molding, injection molding, or the like can be used.

The remote atmospheric plasma treatment may be performed in the same manner as the atmospheric plasma treatment in the surface treatment of the molded body 1. The fuel cell separator 30 including the gasket after such atmospheric pressure plasma treatment may be washed with ion-exchanged water heated as necessary.

When the fuel cell separator 30 having such a gasket is formed, even when the gasket 12 is laminated on the separator 20, volatile substances, hydrophobic substances, or the like of the gasket 12 adhere to the surface of the separator 20. Such volatile substances and hydrophobic substances are efficiently removed by atmospheric pressure plasma treatment. When the gasket 12 is laminated on the separator 20, when the gasket 12 volatile material, hydrophobic material, or the like adheres to the separator 20, the hydrophilicity may be reduced. However, as described above, when the atmospheric pressure plasma treatment of the remote method is performed after the lamination of the gaskets 12, the separator 20 is restored to a high hydrophilic state. Therefore, the hydrophilicity of the separator 20 incorporated in the fuel cell can be further improved, whereby the long-term durability of the fuel cell can also be improved.

After the gasket 12 is attached to the separator 20, it is also preferable to perform the cleaning treatment in the same manner as in the case where the separator 20 is subjected to the surface treatment. In this case, by attaching the gasket 12, impurities adhered to the separator 20 can be sufficiently removed by the washing process. It is also preferable that after the gasket 12 is attached to the separator 20, the cleaning treatment is performed after the remote atmospheric plasma treatment.

In the case where the cleaning treatment is included in the surface treatment, or when the separator 20 is subjected to the cleaning treatment after the gasket 12 is attached to the separator 20, in the fuel cell C including the separator 20, Since the impurity which causes the fuel cell C deterioration is removed from the surface of the separator 20 by the washing process, performance deterioration with time etc. by elution of an impurity from the separator 20 is suppressed. In addition, since the defects, such as the fall of the graphite particle by the washing | cleaning process, are suppressed in this separator 20, the performance fall of the fuel cell C by the fall of the graphite particle from the separator 20, etc. is also suppressed.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail according to an Example.

Examples 1 to 21 and Comparative Examples 1 to 4

About each Example and a comparative example, the component shown in Table 1, 2 was put into the stirring mixer (Dalton-made "(5X) DMV-rr type") so that it may become the composition shown in Table 1, 2, and stirred and mixed, The obtained mixture was ground to a particle size of 500 µm or less with a grain sizer.

The obtained pulverized product was compression molded under the conditions of a mold temperature of 185 ° C, a molding pressure of 35.3 MPa, and a molding time of 2 minutes. Thereafter, the mold was closed while pressing, held for 30 seconds, and then the mold was opened to take out the molded body 1.

The shape of the obtained molded object 1 was 200 mm x 250 mm and thickness 1.5 mm. 57 gas supply and discharge grooves 2 having a length of 250 mm, a width of 1 mm and a depth of 0.5 mm are formed on one surface of the molded body 1, and gas supply and discharge grooves having a length of 250 mm, a width of 0.5 mm and a depth of 0.5 mm are provided on the other surface. ) Was formed 58.

The wet blasting process using the commercially available wet blasting slurry was added to the surface of this molded object 1 except the comparative example 1.

Table 1 and 2 show the results of measuring the arithmetic mean height Ra (JISB0601: 2001) of the molded body 1.

After the wet blasting treatment, in Examples 4 and 5, a drying treatment was applied to the molded body 1. In this drying process, the air blow process which blows out 60 degreeC air to the surface of the molded object 1 was performed, and the water droplet on the surface of the molded object 1 was removed.

After the said process, the moisture absorption of the molded object 1 is shown to Table 1, 2. This moisture absorption rate is derived according to the weight change of the molded object 1, when the molded object 1 is heated at 90 degreeC for 1 hour.

Thereafter, atmospheric pressure plasma treatment was applied to the molded body 1. In atmospheric pressure plasma processing, except for the comparative example 2, it processed by the remote system, and the comparative example 2 was processed by the direct system. As the plasma processing apparatus, AP-T series manufactured by Sekisui Chemical Co., Ltd. was used. Treatment conditions are as shown in Tables 1 and 2. In addition, in Table 1, 2, "process temperature" is the temperature of the molded object 1 at the time of atmospheric pressure plasma processing, and 60 degreeC is temperature more than a dew point.

After the atmospheric plasma treatment, in Examples 5 to 7, the molded body 1 was immersed in ion-exchanged water and subjected to water contact treatment.

[Evaluation test]

About each Example and the comparative example, the evaluation test shown next was implemented. The results are shown in Tables 3 and 4.

(Bending strength evaluation)

In each Example and the comparative example, the molded article for the bending strength measurement of 80 mm x 10 mm x 4 mm dimension was produced by the method similar to the case of manufacturing the separator 20, and the bending strength was measured based on JISK6911. The distance between the points was 64 mm and the cross head speed was 2 mm / minute.

(Contact resistance evaluation 1)

In each Example and the comparative example, the thickness of the separator 20 is formed in 2 mm, carbon paper is arrange | positioned above and below this separator 20, and copper plate is arrange | positioned above and below, and surface pressure 1.0 MPa in a vertical direction. Of pressure. Thereafter, the voltage between the two carbon papers was measured with a voltmeter, and the current between the two copper plates was measured with an ammeter, and the resistance (average value) was calculated using the results. And the used carbon paper is a TGP-H-M series (090M: thickness 0.28mm, 120M: thickness 0.38mm) by Toray Corporation.

(Contact resistance evaluation 2)

In the contact resistance evaluation 1, the surface pressure in the vertical direction during measurement was changed to 0.5 MP.

(TOC evaluation)

In accordance with JISK 0551-4.3, first, the molded bodies 1 of the Examples and Comparative Examples were washed with methanol for 1 minute, and then washed with ion-exchanged water for 1 minute. Subsequently, the molded body 1 and the ion-exchange water were put in the glass container so that ion-exchange water might become 100 ml with respect to the mass 10g of the molded object 1, and it processed at 90 degreeC for 50 hours. After adding phosphoric acid in the ion-exchanged water after treatment and adjusting it to pH2 or less, the amount of organic carbonates was measured by the wet oxidation-infrared type TOC measurement method (using the Toray Engineering company "Toore Astro TOC automatic analysis total MODEL1800"). Measured.

(Hydrophilicity evaluation)

1 μL of ion-exchanged water is dropped into the gas supply discharge groove 2 having a width of 0.5 mm and a depth of 0.5 mm of the separator 20 obtained in each of the examples and the comparative examples, and this water drop is a groove for the gas supply discharge. The length spreading in the direction along the longitudinal direction of (2) was measured.

In addition, after drying this separator 20 in 90 degreeC warm water, and leaving it for a fixed time, it dried. The leaving time was made into 500 hours, 1 000 hours, 1500 hours, and 2000 hours. About the separator 20 after such a process, the length which the water droplet in the gas supply discharge groove 2 spreads was measured similarly to the above.

(Static contact angle evaluation1)

The separator 20 obtained by each Example and the comparative example is arrange | positioned horizontally, and ion-exchange water is dropped with the dropper on the uneven part (rib, 21) of this separator 20, and is manufactured by Kyowa Interface Science Co., Ltd. Using the manufactured measuring device (article number "CA-W150"), the static contact angle with water was measured.

In addition, after drying this separator 20 in 90 degreeC warm water, and leaving it for a fixed time, it dried. The leaving time was made into 500 hours, 1 000 hours, 1500 hours, and 2000 hours. About the separator 20 after such a process, the static contact angle with water was measured similarly to the above.

(Static contact angle evaluation2)

The separator 20 obtained by each Example and the comparative example is arrange | positioned horizontally, and ion-exchange water is dropped with the dropper on the uneven part (rib, 21) of this separator 20, and is manufactured by Kyowa Interface Science Co., Ltd. Using the manufactured measuring device (article number "CA-W150"), the static contact angle with water was measured.

Moreover, after this separator 20 was thrown in 100 degreeC warm water and left to stand for 1 hour, the process which made heating and drying at 90 degreeC for 2 hours and making it 1 cycle was repeated. The cycle number to be processed was 50 times, 100 times, 200 times, and 500 times. About the separator 20 after this process, the static contact angle with water was measured similarly to the above.

(Soluble ion analysis)

The molded body 1 of each Example and the comparative example was wash | cleaned for 1 minute with methanol, and then it was wash | cleaned for 1 minute with ion-exchange water. Subsequently, the molded body 1 and the ion-exchanged water were placed in a polyethylene container so that the ion-exchanged water became 100 ml with respect to 10 g of the mass of the molded body 1, and the process was performed at 90 degreeC for 50 hours. Na ion concentration and Cl ion concentration of ion-exchanged water (extraction water) after the treatment were measured by ion chromatography ("CDD-6A" manufactured by Shimadzu Corporation).

(Electrical conductivity evaluation)

After washing for 1 minute with the methanol of each Example and comparison, it was washed for 1 minute with ion-exchanged water. Subsequently, the molded body 1 and the ion-exchanged water were placed in a polyethylene container so that the ion-exchanged water became 100 ml with respect to 10 g of the mass of the molded body 1, and the process was performed at 90 degreeC for 50 hours. Ion-exchanged water (extracted water) after the treatment was measured with a conductivity meter.

(Evaluation of the voltage fluctuation of the fuel cell)

After the ethylene-propylene-diene rubber was apply | coated to the outer peripheral part of the separator 20 obtained by each Example and the comparative example by screen printing, the gasket 12 was formed by heat-vulcanizing. This obtained the fuel cell separator 30 which has a gasket. In addition, the fuel cell separator 30 having this gasket is interposed between a membrane-electrode composite 5 made of an electrolyte 4 and a gas diffusion electrode (fuel electrode 31 and oxidant electrode 32). The fuel cell C which consists of a standard unit cell (electrode area 25cm <^2> ) of the Japan Automobile Research Institute was produced. The fuel cell C was supplied for 1000 hours by supplying air at a flow rate of 2.0 NL / min as fuel gas and hydrogen at a flow rate of 0.5 NL / min as an oxidant gas, with the external circuit connected to the fuel cell C. It was operated continuously. The state of fluctuation of the power generation voltage V during operation of the fuel cell C over time was examined. The result was expressed as the value of the percentage ((E1 / E0) x 100 (%)) with respect to the initial value of the voltage | voltage after a fluctuation | variation. E1 is the voltage after change and E0 is the initial voltage.

Moreover, in Examples 1-19, after attaching the gasket 12 to the separator 20, the atmospheric pressure plasma process of a remote system is performed with respect to this separator 20 on the conditions similar to the surface treatment in Example 1. The fuel cell separator 30 which has a gasket was produced | generated. Using the fuel cell separator 30 which has such a gasket, the fuel cell of the structure shown in FIG. 4 was produced similarly to the above. Also for this fuel cell, the fluctuation in voltage was measured in the same manner as described above.

(Limit oxygen utilization rate evaluation)

Using the separator 20 obtained by each Example and the comparative example, the fuel cell C which has a structure similar to evaluation of the voltage variation of the said fuel cell was produced.

This fuel cell C was carried out while increasing the fuel utilization rate by 50% at 50% fuel utilization rate under conditions of an oxygen utilization rate of 40% and a current density of 0.15 A / cm ² . As a result, the fuel utilization rate of the cell voltage which was originally 700 mV or more fell rapidly. The test was stopped when the cell voltage fell below 600 mV. The driving test for 5 hours was performed at the fuel utilization rate of 5%, and the maximum fuel utilization rate which can operate stably without the vibration of a cell voltage was made into the limit fuel utilization rate.

In addition, the fuel cell C was increased by 5% at an oxygen utilization rate of 30% under conditions of a fuel utilization rate of 60% and a current density of 0.3 A / cm ² , and the test was stopped when the cell voltage was below 600 mV. The driving test for 5 hours was performed at each oxygen utilization rate, and the maximum oxygen utilization rate which can operate stably without showing the vibration of a cell voltage was made into limit oxygen utilization rate. When this limit oxygen utilization rate is high, it can be said that the gas supply-discharge groove | channel 2 of the separator 20 is suppressed from being blocked by adhesion of water droplets, and it can be said that the stability of electric power generation is improved.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

The details of each component in the table are as follows.

<Composition>

Epoxy resin A: Cresol novolak-type epoxy resin ("EOCN-1020-75" by the Japanese chemical company, epoxy equivalent 199, melting point 75 degrees Celsius)

Epoxy resin B:

Bisphenol F type epoxy resin (we produce "830CRP" of Nippon Ink Chemical Co., Ltd., epoxy equivalent 171, liquid at 25 degrees Celsius)

Curing agent A: A novolak-type phenol resin ("PSM6200" by Gunyoung Chemical Co., Ltd., OH equivalent 105).

Curing agent B: Multifunctional phenolic resin ("MEH-7500" manufactured by Meiwa Chemical Co., Ltd., OH equivalent 100)?

Phenolic resin A: Resor type phenol resin ("Sample A" by Military Chemical Co., Ltd., melting point 75 degreeC, ortho-ortho 25-35% by 13C-NMR analysis, ortho-para 60-70%, para-para 5-10) %)?

Curing accelerator A: Triphenyl phosphine ("TPP" made by Hokko Chemical Co., Ltd.)?

Curing accelerator B: 2-heptadecyl imidazole (Shikoku Kasei Kogyo Co., Ltd.), weight reduction 3.1%?

Curing accelerator C: 2-undecyl imidazole (Shikoku Kasei Kogyo Co., Ltd.), weight loss 3.2%?

Natural graphite ("WR50A" by the middle and monthly graphite industry company, an average particle diameter of 50 micrometers, ash 0.05%, sodium ion 4 ppm, chloride ion 2 ppm).

Artificial graphite ("SGP100" made by Esushi-shi Corporation, average particle diameter 100 micrometers, ash 0.05%, sodium ion 3 ppm, chloride ion 1 ppm.

Coupling agent: Epoxy silane ("A187" by the Japan Unicar Company).

Wax A: Natural carnauba wax (Dinichi Chemical Co., Ltd. "H 1-100", melting point 83 degreeC)

Wax B: Montane bis amide (Dinichi Chemical Co., Ltd. product "J-900", melting | fusing point 123 degreeC)

And the weight reduction of the hardening accelerators B and C heated the hardening accelerators B and C on the conditions of the measurement start temperature of 30 degreeC, the temperature rise rate of 10 degree-C / min, holding temperature of 120 degreeC, and holding time of 30 minutes of holding temperature. In the case of weight loss.

(Depth / width evaluation of the groove)

In Example 1-21, the depth B of the gas supply-discharge groove 2 is 1 mm, and the ratio A / B of width A and depth B is 0.8, 1, 5, 10. Each separator 20 was produced.

Static contact angle evaluation was performed with respect to the inner surface of the gas supply discharge groove 2 of each separator 20. As shown in FIG. As a result, in either case of Example 1-21, the static contact angle with water became 25 degrees when A / B was 0.8, and became 20 degrees when A / B was 1, 5, or 10.

[Examples 22 to 35]

In Example 4, after applying the wet blast treatment to the molded body 1, and before performing the drying treatment, ultrasonic vibration is applied to the demineralized water using a high-megasonic US shower of Kayyo Co., Ltd. The demineralized water was discharged from the nozzle toward the surface of the molded body 1 to apply a cleaning treatment to the molded body 1. In Examples 20-24, the liquid to which ultrasonic vibration was applied was discharged from the nozzle arrange | positioned above this molded object 1 in the state which stopped the molded object 1. In FIG. In Examples 25-33, the liquid to which ultrasonic vibration was applied was discharged from the nozzle arrange | positioned above the movement path of this molded object 1, conveying the molded object 1. As shown in FIG. Demineralized water or alkaline ionized water was used as the liquid, and RUMICEKO-205 (Sales Co., Ltd.) was used as the alkaline ionized water. The conditions of the washing process in each Example are as showing in Table 5.

The molded body 1 is subjected to a drying treatment, a remote atmospheric plasma treatment, and a water contact treatment in this order, and the gasket 12 is applied to the separator 20 by the method described in the above-described evaluation of the fluctuation of voltage of the fuel cell. Mounted. Subsequently, before performing atmospheric pressure plasma processing by a remote system, this separator 20 was wash | cleaned on the conditions similar to the above. Subsequently, the separator 20 is warm-dried and then subjected to a remote atmospheric plasma treatment under the same conditions as the surface treatment in Example 1, and further subjected to water contact treatment, thereby providing a fuel cell separator 30 having a gasket. Got.

[Appearance evaluation]

The external appearance of the fuel cell separator 30 having the gasket obtained in Example 4 and Examples 22 to 35 was observed, and the case where abnormality such as ○ or black stem was recognized was evaluated as x when the abnormality was not recognized. .

The results are shown in Table 5 below.

[Impurity Solubility Evaluation]

From the fuel cell separator 30 having the gasket obtained in Example 4 and Examples 22 to 35, 10 g of the sample was cut out in a plane of 50 mm x 1 mm in plan view, and the sample was cut into 90 g of ion-exchanged water at 90 ° C. Immerse for 100 hours.

The electrical conductivity of the ion-exchanged water after this treatment was measured, and the value was made into the index of impurity elutability from the fuel cell separator 30 which has a gasket.

The results are shown in Table 5 below.

[Table 5]

Claims (21)

A molded article obtained by molding a molding composition containing a thermosetting resin containing an epoxy resin, a curing agent containing a phenolic compound, and graphite particles, and having an equivalent ratio of the epoxy resin to the phenolic compound in the range of 0.8 to 1.2. Including the process of surface-treating on a surface,
The surface treatment includes a wet blast treatment and a remote atmospheric plasma treatment after the wet blast treatment,
The weight loss when the said composition for shaping | molding is heated on conditions of 30 degreeC of measurement start temperature, 10 degreeC / min of temperature rise rate, 120 degreeC of holding temperature, and holding temperature is 5% or less, and 2 Containing a substituted imidazole having a hydrocarbon group thereon,
Method for producing a fuel cell separator. The method of claim 1,
The epoxy resin is a cresol novolac type epoxy resin,
The phenolic compound is a novolac phenolic resin,
Method for producing a fuel cell separator. delete The method according to claim 1 or 2,
The arithmetic mean height Ra (JIS B0601: 2001) of the surface of the molded object by the said wet blasting process shall be 0.4-1.6 micrometers,
Method for producing a fuel cell separator. The method of claim 4, wherein
The arithmetic mean height Ra (JIS B0601: 2001) of the surface of the molded object by the wet blasting process is set to be 0.4 μm or more and less than 1.0 μm,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
The plasma generation gas in the atmospheric pressure plasma treatment is nitrogen gas having an oxygen gas content of 2000 ppm or less,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
The molding composition contains an internal release agent,
Method for producing a fuel cell separator. delete The method according to claim 1 or 2,
The molding composition contains triphenyl phosphine
Method for producing a fuel cell separator. The method according to claim 1 or 2,
The said surface treatment includes the drying process which dries the said molded object to moisture absorption 0.1% or less after the said wet blasting process and before atmospheric pressure plasma processing,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
The surface treatment includes a water contact treatment for bringing the surface of the molded body into contact with water after the atmospheric pressure plasma treatment.
Method for producing a fuel cell separator. The method according to claim 1 or 2,
In the surface to which the surface treatment is performed of the molded object before the said surface treatment, the groove | channel for gas supply discharge which the ratio (A / B) of width | variety A and depth B is 1 or more is formed,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
By the said surface treatment, the contact resistance of the surface of the said molded object shall be 15 m (ohm) cm <^2> or less,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
By the said surface treatment, the static contact angle with the water of the surface of the said molded object shall be in the range of 0-50 degrees,
Method for producing a fuel cell separator. The method according to claim 1 or 2,
The surface treatment includes a cleaning treatment for applying ultrasonic vibration to the liquid and simultaneously discharging the liquid toward the molded body.
Method for producing a fuel cell separator. 16. The method of claim 15,
In the cleaning process, the frequency of the ultrasonic vibration applied to the liquid is 900 kHz or more.
Method for producing a fuel cell separator. The method of claim 16,
In the washing treatment, the liquid is alkaline ionized water,
Method for producing a fuel cell separator. A fuel cell separator manufactured by the method of claim 17. A gasket is formed by laminating a gasket on the fuel cell separator manufactured by the method according to claim 17, and then performing a remote atmospheric plasma treatment on the surface of the fuel cell separator.
Method for producing a fuel cell separator. A gasket is formed by laminating a gasket on the fuel cell separator manufactured by the method according to claim 17, and then applying a ultrasonic vibration to the liquid and performing a cleaning process for discharging the liquid toward the fuel cell separator.
Method for producing a fuel cell separator. After laminating a gasket on the fuel cell separator produced by the method according to claim 17, a remote atmospheric plasma treatment is again applied to the surface of the fuel cell separator, and then the fuel cell separator is laminated with the membrane-electrode composite. Process
Method for producing a fuel cell separator.

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