JP2009099556A - Fuel cell separator using hydrophilic treatment composition, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to retain good hydrophilicity for a comparatively long period of time right after power generation even with a carbon separator for a fuel cell. <P>SOLUTION: Active components for removing water from an aqueous solution or a water dispersion solution of a hydrophilic treatment composition containing carbodiimide resin with water solubility and/or water dispersibility, is carried on a gas flow channel surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell separator using a hydrophilic treatment composition and a method for producing the same.

  In the separator of a fuel cell, even when water generated by the cell reaction or condensed water stays in the gas flow path, it is important to ensure a reaction gas flow rate above a certain level and effectively drain the gas flow from the separator unit. (For example, refer to Patent Document 1).

As a device for improving drainage, water repellent treatment and hydrophilic treatment on the surface of the gas channel are widely known in addition to improvement of the structure and form of the gas channel. As the surface treatment, water repellent treatment was mainly used at first, but hydrophilic treatment is also widely used (for example, see Patent Documents 2, 3 and 5). This is thought to be due to the natural force that exerts the so-called capillary flow characteristics, with the driving force being the force that the liquid spreads by itself. Further, as a fuel cell separator, there is also known a fuel cell graphite separator which employs graphite in addition to metal to improve conductivity (see, for example, Patent Documents 4 and 5). In particular, Patent Document 5 cannot ensure the electrode reaction caused by the reaction of the fuel gas and the oxidant gas, which is important for ensuring the power generation efficiency, without applying or mixing a hydrophilic substance that lowers the conductivity. A separator for a fuel cell made of carbon or graphite and containing poly (meth) acrylate, which satisfies both of the hydrophilicity important for drainage of generated water, and its surface contact angle with water Has proposed a fuel cell separator characterized by having a volume resistivity in the plane direction of 50 mΩ · cm or less, and having both hydrophilicity and electrical conductivity.
JP 2005-327532 A JP 2002-313356 A JP 2002-298771 A JP-A-2005-71699 JP 2002-352813 A

  By the way, in the carbon separator for fuel cells, the hydrophilicity of the surface is one of the important characteristics that affect the power generation performance, and in order to achieve the required capillary flow characteristics, the contact angle of water is controlled within a predetermined range and stabilized. There is a need to.

  However, the surface of the carbon separator for fuel cells inherently exhibits water repellency, the contact angle of water is around 100 °, the hydrophilicity gradually increases due to the high-temperature water generated during power generation, and continues to be in contact with hot water for about 500 hours. However, since it is water-repellent for the first 500 hours after the start of power generation, there is a problem that the power generation performance during that time is not stable.

  The object of the present invention is to use a hydrophilized composition that can maintain good hydrophilicity for a relatively long period of time immediately after power generation, even if it is a carbon separator for a fuel cell, based on such new knowledge. An object of the present invention is to provide a separator for a fuel cell and a method for manufacturing the same.

  In order to solve the above-mentioned problems, the separator for a fuel cell according to the present invention contains an aqueous solution of a hydrophilic treatment composition containing a water-soluble and / or water-dispersible carbodiimide resin, or an active ingredient excluding water in an aqueous dispersion. It is characterized in that it is supported on.

  In such a configuration, the active ingredient excluding water in the hydrophilization composition is supported on the surface of the gas channel, so that the surface of the gas channel becomes hydrophilic and has hydrophilic durability when contacted with hot water. Enhanced.

  Such a fuel cell separator is prepared by coating an aqueous solution or water dispersion of a hydrophilization composition containing a water-soluble and / or water-dispersible carbodiimide resin on the surface of a gas flow path of a fuel cell separator substrate, It is manufactured by a method for manufacturing a separator for a fuel cell, characterized in that a hydrophilization treatment step is carried out in which an active ingredient excluding water in the hydrophilization treatment composition is carried on the surface of the gas flow path. be able to.

  In the fuel cell separator and the method for producing the same, the hydrophilic treatment composition may further contain a quaternary ammonium silicate.

  In the fuel cell separator and the manufacturing method thereof, the hydrophilic treatment composition may further include a silane coupling agent.

  In the fuel cell separator and the method for producing the same, the hydrophilic treatment composition includes 1 to 100 parts by mass of a carbodiimide resin (A), 0 to 100 parts by mass of a quaternary ammonium silicate (B), and silane. The coupling agent (C) may be contained in a composition in the range of 0 to 10 parts by mass.

  In the fuel cell separator and the method for producing the same, the surface of the gas channel after supporting the active ingredient may be further treated with an inorganic acid.

  In such a configuration, especially, the hydrophilic maintenance time becomes long when exposed to an environment of high temperature and low humidity.

  According to the separator for a fuel cell using the hydrophilization composition of the present invention and the method for producing the same, it is possible to maintain hydrophilicity for a long time from the start of power generation in the carbon separator for a fuel cell as well as a metal separator. Thus, the fuel cell using the carbon separator according to the present invention can exhibit stable power generation performance over a long period from the start of power generation.

  Further, when the surface of the gas flow path after supporting the active ingredient is a fuel cell separator treated with an inorganic acid, it is possible to maintain hydrophilicity for a long time from the start of power generation, and a fuel cell using the same Then, a high operating temperature is allowed and stable power generation performance can be exhibited over a long period from the start of power generation.

  Hereinafter, embodiments of a fuel cell separator using the hydrophilic treatment composition of the present invention and a method for producing the same will be described with reference to the drawings.

  The separator for fuel cells using the hydrophilization composition of the present embodiment and the manufacturing method thereof are mainly used for improving drainage performance in the gas flow path 2 in the carbon separator 1 for fuel cells as shown in FIGS. This is a technique aimed at maintaining hydrophilicity for a long period of time, including control of the hydrophilicity within a predetermined range as required in addition to increasing hydrophilicity.

As described above, the surface of the gas flow path of the fuel cell carbon separator is inherently water-repellent and has a water contact angle of about 100 °, and the hydrophilicity gradually increases due to the high-temperature water generated during power generation, and it takes about 500 hours. The contact angle of water drops to about 60 ° if it keeps in contact with warm water, but the present inventor first explained that the power generation performance is not stable during the first 500 hours after the start of power generation. From the beginning of power generation, an aqueous dispersion of a quaternary ammonium silicate used for imparting hydrophilicity to prevent fogging with rainwater or the like was applied to a carbon separator for a fuel cell in order to exhibit a predetermined range of hydrophilicity. However, it was found that the contact angle of water once lowered within 500 hours after immersion in warm water increased. This is because the quaternary ammonium silicate is not expected to be altered or deteriorated, and the quaternary ammonium silicate dropped off from the surface of the carbon separator for fuel cells mainly composed of graphite, and the initial surface of the separator was exposed. It means that. Here, the adherence of the quaternary ammonium silicate to the gas flow path surface of the carbon separator for a fuel cell in a contact environment with high-temperature water has become a first problem.

  Next, in order to solve the first problem, the inventor has surface treated the carbon separator for a fuel cell with an improved composition containing a suitable silane coupling agent in a quaternary ammonium silicate. Experimented with thought. According to this improved composition, even when contacted with high-temperature water, it was possible to maintain the hydrophilicity such that the contact angle of water was less than 60 ° for 500 hours or more after the start of power generation. However, in a practical experiment using a fuel cell, a second problem of losing hydrophilicity occurred in a short period of time within 500 hours after immersion in warm water.

  As a result of various investigations by the present inventor, it is known that elution from the fluorine-based polymer membrane occurs due to deterioration of the fluorine-based polymer membrane sandwiched between the electrodes of the fuel cell (for example, fluorine elution) (NIKKEI MONOZUKURI, June 2007 issue) Bulletin of technical development “Responsible for 10 years of durability, but fuel cell manufacturers for home use are backwaters” on page 25, page 27 “med for 10 years, 40,000 hours” ), Specifically, due to hydrofluoric acid, it seems that the etching action of hydrofluoric acid, which is well known for glass surface treatment, affects the quaternary ammonium silicate on the separator surface.

  As a result of these trial and error research and development, the present inventor has discovered a new hydrophilization treatment composition that can maintain good hydrophilicity for a relatively long period of time immediately after power generation even for a carbon separator for a fuel cell. did.

  Here, as the carbon separator 1 for a fuel cell, a material using graphite having excellent conductivity as a main component, and using a thermosetting resin such as a phenol resin or an epoxy resin as a binder, if necessary, is further hydrophilic. Development was repeated while repeating tests to improve performance. For example, a fuel cell separator material (trade name “G347B”) manufactured by Tokai Carbon Co., Ltd. was used. The surface of the substrate as it is is water-repellent, and an experimental example in which spherical drops of water (droplet volume: 1.5 μl) from the nozzle 3 is dropped using a contact angle meter (DM500 manufactured by Kyowa Interface Science Co., Ltd.) Then, as shown in FIG. 6, the contact angle was 102 °.

  In contrast, the fuel cell separator of the present embodiment has an aqueous solution of a hydrophilic treatment composition containing a water-soluble and / or water-dispersible carbodiimide resin or an active ingredient excluding water in the water dispersion on the surface of the gas channel. It is assumed that it is carried. Thereby, the active ingredient except the water in the hydrophilization treatment composition is carried on the surface of the gas channel, so that the surface of the gas channel becomes hydrophilic and durability of hydrophilicity when contacting with warm water can be enhanced.

  Such a fuel cell separator removes water after coating the surface of the gas flow path of the fuel cell separator with an aqueous solution or water dispersion of a hydrophilic treatment composition containing a water-soluble and / or water-dispersible carbodiimide resin. And a hydrophilization treatment step in which an active ingredient other than water in the hydrophilization treatment composition is supported on the surface of the gas flow path. it can.

  Here, the hydrophilic treatment composition may further contain quaternary ammonium silicate.

  Further, the hydrophilic treatment composition may further contain a silane coupling agent.

  More specifically, the hydrophilic treatment composition includes 1 to 100 parts by mass of a carbodiimide resin (A), 0 to 100 parts by mass of a quaternary ammonium silicate (B), and a silane coupling agent (C ) In the range of 0 to 10 parts by mass, even in the case of the carbon separator 1 for a fuel cell, depending on the selection of the composition within the above range, an experimental example under the same dropping conditions is shown in FIG. As shown in FIG. 1, the high hydrophilicity such as a contact angle of 13.6 ° was exhibited, and the hydrophilicity could be maintained for a long time in a high-temperature water environment of 80 ° C.

  Here, an example of drainage performance experiment utilizing so-called capillary flow characteristics due to hydrophilicity will be described. FIGS. 2 to 5 show the wetting behavior per second of the water droplets 4 dropped in the same manner as in the dropping experiment example. In FIG. 2, the dropped water 4 is in contact with the bottom surface of the separator flow path 2, but is held between the nozzle 3 moving down to the dropping position and still has a spherical shape. In FIG. 3, 1 second elapses while the nozzle 3 moves up from the position of FIG. In FIG. 4, water 4 spreads to the upper part of both side surfaces of the gas flow path 2 after 1 second from FIG. 3, while the volume decreases to less than ½ compared to FIG. 3. ing. This decrease means that the gas flow path 2 is horizontal but wet and spread in the longitudinal direction of the gas flow path 2. In FIG. It is shown that the amount of the gas is reduced to a small amount remaining at the corner of the gas channel 2 and further spreads in the longitudinal direction of the gas flow path 2. Here, it is understood that the wetting and spreading of the water 4 is a flow in which the driving force is a force in which the liquid wets and spreads by itself, and it is understood that the important drainage required for the fuel cell separator can be enhanced by improving the hydrophilicity.

  Such long-term maintenance of hydrophilicity has been a problem in the carbon separator 1 for the fuel cell according to the present embodiment, in which adhesion of the hydrophilization treatment composition and not being affected by hydrofluoric acid have been problems. It can be said that it was clear.

  In order to maintain such hydrophilicity and its long-term maintenance, an aqueous solution or aqueous dispersion of a water-soluble and / or water-dispersible carbodiimide resin (A) is an essential composition according to various test examples of the present inventor. The composition is not particularly essential.

  However, in the combination of 1 to 100 parts by mass of the water-soluble and / or water-dispersible carbodiimide resin (A) and 0 to 100 parts by mass of the quaternary ammonium silicate (B), the inventors' test. According to the example, the contact angle of water immediately after the hydrophilization treatment, that is, the degree of hydrophilicity can be arbitrarily changed by changing the blending ratio of both, and the contact angle or hydrophilicity required by such control can be changed. In this sense, it can be used for various purposes.

  The aqueous solution or aqueous dispersion of the water-soluble and / or water-dispersible carbodiimide resin (A) that is essential as described above is water-soluble by imparting hydrophilic segments to a resin having two or more carbodiimide groups in one molecule. Alternatively, a carbodiimide resin made water-dispersible can be used. For example, trade names “Carbodilite V-02, V-02-L2, V-04, SV-02 (above are water-soluble), E-01, E-02, E-03A, E-manufactured by Nisshinbo Co., Ltd. 04 (the above is an aqueous dispersion) "(the solid concentration is about 40% in all cases). These can be used alone or in combination of two or more.

In addition, as an aqueous dispersion of the quaternary ammonium silicate (B) which is not essential, the general formula (R3N) 2O.nSiO2 (where R is an alkyl group having 1 or more carbon atoms, and n is 1 or more) (Integer). Specific examples include dimethylethanolammonium silicate, monomethyltripropanolammonium silicate, dimethylpropanolammonium silicate, monoethyltripropanolammonium silicate, and the like. “Ceramica MS85” (solid content concentration is about 35.5%) can be used.

  The non-essential silane coupling agent (C) may be a known commercial product, for example, an amino type such as 3-aminopropyltriethoxysilane, an epoxy type such as 3-glycidoxypropyltrimethoxysilane, or vinyl tri A methacrylic silane coupling agent such as vinyl-based methoxysilane or methacryloxypropyltrimethoxylasilane can be used.

In these compositions (A) to (C), the blending amount is as described above,
The water-soluble and / or water-dispersible carbodiimide resin (A) is 1 to 100 parts by mass. The quaternary ammonium silicate (B) is 0 to 100 parts by mass. The silane coupling agent (C) is 0 to 10 parts by mass. It is desirable to select the blending ratio, but when the surface treatment is performed on the flow path of the carbon separator with a composition containing the essential carbodiimide resin (A) alone, the initial water contact angle becomes relatively large. In the case of surface treatment with a composition comprising a combination of a carbodiimide resin (A) and a quaternary ammonium silicate (B), the higher the compounding ratio of the quaternary ammonium silicate (B), the higher the initial water content. The contact angle becomes smaller. Therefore, for example, in order to further increase the initial hydrophilicity, the mixing ratio (A) / (B) of the active ingredient of the carbodiimide resin (A) and the quaternary ammonium silicate (B) is 30 parts by mass / 70. It is desirable to set it as a mass part-1 mass part / 99 mass parts.

  Moreover, you may mix | blend a silane coupling agent (C) with the surface treatment in said each case. Among the carbodiimide resins (A), those that are water-dispersible can be used in an earlier stage of water than in the case of the water-soluble carbodiimide resin (A), even when blended with the quaternary ammonium silicate (B). The contact angle tends to increase. In that case, the initial contact angle of water can be reduced by blending the silane coupling agent (C).

  It is preferable that the compounding quantity of a silane coupling agent (C) shall be 1-10 mass parts with respect to 100 mass parts of carbodiimide resin (A) and a quaternary ammonium silicate (B). More preferably, this is 5 to 10 parts by mass. Compounding in excess of 10 parts by mass is economically meaningless, although there is no particular problem with the characteristics as a carbon separator.

  The hydrophilic treatment composition in these various formulations can be diluted with water.

  Here, the blending amount of the dilution water is preferably such that the concentration of the active ingredient excluding water of the hydrophilization treatment composition of the present invention is 30% by mass to 0.5% by mass. When the concentration of the active ingredient exceeds 30 parts by mass, the amount of adhesion to the carbon separator is too much, and when the quaternary ammonium silicate content is high, cracks are likely to occur in the coating film. When the blending ratio of the dispersible carbodiimide resin is high, the adhesiveness of the coating film increases and it becomes difficult to handle the carbon separator, which is not preferable. Moreover, when the density | concentration of an active ingredient is less than 0.5 mass%, the application amount of an active ingredient will decrease and hydrophilicity will become low.

In order to produce the fuel cell carbon separator 1 capable of maintaining the above high hydrophilicity over a long period of time,
The water-soluble and / or water-dispersible carbodiimide resin (A) is 1 to 100 parts by mass. The quaternary ammonium silicate (B) is 0 to 100 parts by mass. The silane coupling agent (C) is 0 to 10 parts by mass. After coating the surface of the gas flow path of the fuel cell carbon separator with the hydrophilized composition selected in step (b), the water is removed to remove the active ingredient from the hydrophilized composition. What is necessary is just to carry | support to the gas flow path surface, and the separator for fuel cells whose surface exhibits hydrophilicity for a long term by this can be obtained.

  Here, the carbon separator base material for a fuel cell as an adherend to which the hydrophilic treatment composition is applied may be used as it is molded, but in order to improve the adhesion with the hydrophilic treatment composition. In addition, as a pretreatment, it is preferable to remove a release agent attached to the surface. This can be done by shot blasting or ultrasonic cleaning. In this case, the anchor effect with respect to the active ingredient of the hydrophilic treatment composition can also be obtained by increasing the surface roughness.

  There is no special restriction | limiting in the coating method to the carbon separator surface of a hydrophilic treatment composition, Well-known methods, such as an impregnation method and a spray method, are employable. In the case of the impregnation method, by removing the excess hydrophilization treatment composition adhering to the surface by blowing it off with a blow nozzle or the like, it is suitable for preventing cracking of the coating film and increase in adhesiveness due to an increase in the coating amount. is there.

  As described above, in order to remove water from the hydrophilic treatment composition coated on the surface of the gas flow path of the carbon separator, it is preferable to use drying. Although there is no special restriction | limiting in drying conditions, In order to prevent the curvature of a carbon separator base material, it is preferable that a drying temperature shall be 150 degrees C or less.

  However, an aqueous solution or an aqueous dispersion of a water-soluble and / or water-dispersible carbodiimide resin has surfactant-like properties, so that the compatibility with the gas flow path surface of the carbon separator and wettability are good. Therefore, when the carbodiimide resin is used alone, it is not particularly necessary to take a long time for the impregnation. Even if the gas channel surface is dipped in the carbodiimide solution for a short time, the surface gets wet without spots, and softens and flows by heating during drying, and is fused to the gas channel surface to form a flexible film. Therefore, the surface of the gas channel is roughened by the above-described shot blasting treatment and ultrasonic cleaning as in the case of the quaternary ammonium silicate-based impregnation liquid, which is a rigid fine particle, or immersed in the impregnation liquid for a long time. Therefore, there is no need to aim for the anchor effect, and productivity can be improved and costs can be reduced.

  Here, for further understanding of the present invention, some test examples will be described below for evaluation. However, the present invention is not limited to the test examples shown below.

  Carbodilite SV-02 as an aqueous solution of carbodiimide resin (A), Carbodilite E-02 as an aqueous dispersion of carbodiimide resin (A), Ceramica MS85 as an aqueous dispersion of quaternary ammonium silicate (B), silane coupling agent ( Using C-6011 as C), each hydrophilic treatment composition used in Test Examples 1 to 13 shown in Table 1 was blended. After ultrasonic cleaning for 30 minutes using an ultrasonic cleaner “C1238” manufactured by Ultrasonic Industry Co., Ltd., a carbon separator substrate (Tokai Carbon Co., Ltd.) having a length of 10 cm, a width of 10 cm, and a thickness of 3 mm dried at 80 ° C. for 30 minutes. The product name “G347B” manufactured in the test was immersed in a hydrophilization composition of the formulation used in Test Examples 1 to 13 shown in Table 1 below in an impregnation tank for 30 minutes, pulled up from the impregnation tank, and surfaced with an air nozzle. The excess hydrophilizing composition adhering to the sample was blown away, and then, they were heated at 50 ° C. for 30 minutes and then at 100 ° C. for 1 hour to dry and remove moisture, and the hydrophilicity according to Test Examples 1 to 13 Each of the carbonized carbon separators was obtained.

  Next, for each of the hydrophilized carbon separators according to Test Examples 1 to 10 obtained, water immediately after treatment, after immersion in hot water at 80 ° C. × 500 hours, and after immersion in a 500 ppm hydrofluoric acid aqueous solution at 80 ° C. × 500 hours The contact angle was measured with a contact angle meter (DM500 manufactured by Kyowa Interface Science Co., Ltd.). In Test Example 11, although the contact angle immediately after the hydrophilic treatment was slightly lower than that before the treatment, the test after that was omitted. In Test Example 12, the contact angle immediately after the hydrophilization treatment was low, but adhesiveness was observed, so the subsequent tests were omitted. Furthermore, in Test Example 13, cracks occurred on the surface after the hydrophilization treatment, so the subsequent tests were omitted. The measurement results are shown in Table 2 below.

  From Table 2, the carbon separators for fuel cells of Test Examples 1 to 8 maintain the hydrophilicity such that the contact angle of water is 60 ° or less even after exposure to high temperature water or high temperature hydrofluoric acid for 500 hours. In Examples 9 and 10, the water contact angle is 70 °.

Moreover, about Test Examples 1-12, when it summarizes from the relationship between the active ingredient density | concentration of the hydrophilic treatment composition in the case of a carbodiimide resin alone, and initial (theta) after hydrophilization treatment, the density | concentration of an active ingredient, especially carbodiimide resin is 30. If it exceeds mass%, the contact angle θ of water decreases to about 50 °, but the adhesiveness on the surface of the carbon separator for fuel cells increases and the workability decreases, which is not preferable. In addition, the lower the concentration of the active ingredient, especially the carbodiimide resin, the lower the tackiness and the easier to handle and the workability improves. However, when the concentration is less than 0.5% by mass, the contact angle θ of water reaches around 90 °. This makes it difficult to improve drainage in the gas flow path. As a result, the active ingredient concentration is 30% by mass to 0.5% by mass, the contact angle θ is about 50 ° to less than 90 °, the tackiness is low, and the drainage of the gas flow path is improved. This is an effective range. Moreover, since the active ingredient concentration is 20% by mass to 4% by mass, the contact angle θ can be secured from about 52 ° to about 62 °, the adhesiveness is further reduced, and the drainage of the gas flow path is also improved. It's a range. Further, the active ingredient concentration is 20% by mass to 8% by mass, the contact angle θ can be about 52 ° to about 58 °, and both the adhesiveness and the contact angle θ are low and can be said to be a more preferable range.

  However, recently, high-temperature operation of fuel cells has also been targeted (for example, [URL] http://www.ext.go.jp/b_menu/shingi/jiyutu/gijiyutu2/shiryo/017/060503007/006.htm The Ministry of Education, Culture, Sports, Science and Technology's Leading Project Research Plan interview materials), New Energy and Industrial Technology Development Organization (NEDO) have improved the efficiency of power generation and fuels such as CO under the current operating conditions of a temperature of 70 ° C and a relative humidity of about 100% RH. In view of the wide tolerance of impurities inside, the need for a CO remover and an external humidifier, etc., the temperature will be 80 ° C. and relative humidity 65% RH in 2012, and in 2015, the temperature will be 80 ° C. Announces targets to reach RH-90 ° C and relative humidity 30-40% RH.

  On the other hand, Toyobo is an ion conductive polymer (ICP) used in polymer solid electrolyte fuel cells (PEFC), and it has practical output characteristics even at a low humidity of 80 ° C. and a relative humidity of 10 to 20%. The company has succeeded in developing a high heat-resistant hydrocarbon polymer (SPN polymer), which enables temperatures of 100 ° C or higher. As a result, the current operating temperature of PEFC is about 80 ° C, temperature control is difficult, and there is a problem that the reaction does not proceed unless the amount of platinum catalyst used in the electrolyte membrane is increased. If the operating temperature can be achieved, the accessories can be simplified, leading to a compact PEFC system, and reducing the amount of platinum catalyst will lead to cost reduction ([URL] http: //techon.nikkeibp. co.jp/premium/AT/ATNEWS/20030624/4/). In addition, it is possible to use SPN polymer for higher efficiency of PEFC. With respect to the output characteristics of fluorine polymer at 80 ° C and 80% relative humidity, SPN polymer is 1.7 times, 80 ° C, relative The output characteristics are 1.3 times higher even at a low humidity of 15%.

  Therefore, the present inventor conducted an evaluation test on the relationship between the hydrophilicity obtained with the fuel cell separator according to the previous embodiment and the operating temperature. As a result, it was found that the hydrophilicity is slightly impaired when exposed to a high temperature of 95 ° C. for 4 hours or more.

  Correspondingly, in this embodiment, the separator for a fuel cell that has been hydrophilized and treated with an inorganic acid, which can maintain good hydrophilicity even at high temperatures for a relatively long period of time immediately after power generation, and The manufacturing method is provided. Specifically, the surface of the gas flow path of the fuel carbon separator after the hydrophilic treatment is treated with an inorganic acid such as hydrofluoric acid. Thereby, especially the hydrophilic maintenance time when exposed to an environment of high temperature and low humidity becomes long. Therefore, it is possible to maintain hydrophilicity for a long time from the start of power generation at high temperatures even in the case of carbon separators for fuel cells as well as those made of metal, and fuel cells using the carbon separator according to the present invention have a high operating temperature. And stable power generation performance can be exhibited over a long period from the start of power generation.

In such a carbon separator for a fuel cell, after the hydrophilic treatment composition is coated on the surface of the gas flow path of the fuel cell separator, the water is removed by drying or the like to remove water in the hydrophilic treatment composition. By carrying out an inorganic acid treatment step in which the substrate surface after the hydrophilic treatment step is exposed to an inorganic acid such as hydrofluoric acid in addition to the hydrophilic treatment step in which the active ingredient is supported on the gas flow path surface. can get. The inorganic acid treatment step is performed by immersing the substrate after the hydrophilization step in an inorganic acid solution for a predetermined time, and then the substrate is washed with water and dried.

  Such a hydrophilic treatment for long-term maintenance of hydrophilicity has been a problem in the carbon separator 1 for the fuel cell according to the present embodiment in that it is not affected by the adhesion of the hydrophilization composition or hydrofluoric acid. On the other hand, the inorganic acid treatment after the hydrophilization treatment in this embodiment can be said to have been cleared to a practical level. Inorganic acids including nitric acid, phosphoric acid, hydrochloric acid, boric acid, etc., including hydrofluoric acid, It can be said that it was also useful for improving the hydrophilicity under the conditions. This can be said to be irrelevant to the problem effect of hydrofluoric acid generated during power generation.

  Specifically, hydrofluoric acid is added to the carbodiimide group to hydrophilize the hydrophobic carbodiimide group, thereby further increasing the hydrophilicity of the water-soluble and / or water-dispersible carbodiimide resin as a whole. It is considered that moisture retention under low humidity has been improved, and as a result, high hydrophilicity can be exhibited for a long time from the initial stage of power generation even at high temperatures, and other inorganic acids are considered to have the same effect.

  Here, if a specific manufacturing process is shown, it is as shown in FIG. 7, and the impregnation process which impregnates base materials, such as the carbon separator 1, in the hydrophilization process composition for a hydrophilization process, after an impregnation process An air blowing step for blowing off the excess hydrophilization composition adhering to the base material, a drying step for drying the surface of the base material at, for example, 100 ° C. × 1 hour, an inorganic acid, for example, 500 ppm of hydrofluoric acid, 80 ° C. × Inorganic acid dipping step for immersing the substrate for 12 hours, the substrate after the inorganic acid dipping treatment, for example, a water washing step for washing the front and back with running water for about 10 seconds each, a substrate after washing with water, for example, 100 ° C. * The drying process of drying in 1 hour is sequentially performed.

  Here, for further understanding of the present invention, several test examples 14 to 17 are evaluated below, but the present invention is not limited to the test examples shown below.

  In each of Test Examples 14 to 17, a carbon separator substrate (product name “G347B” manufactured by Tokai Carbon Co., Ltd.) having a length of 10 cm, a width of 10 cm, and a thickness of 3 mm was used, and Test Examples 14 and 15 were processed in the steps shown in FIG. Test Examples 16 and 17 were processed in the steps shown in FIG. The process shown in FIG. 8 is obtained by omitting a series of inorganic acid treatment processes, that is, an inorganic acid dipping process, a water washing process, and a drying process from the process shown in FIG. The composition of the hydrophilization treatment composition used in Test Examples 14 and 16 is 100 parts by mass of carbodilite SV02 and 400 parts by mass of water, and corresponds to Test Example 1. The composition of the impregnating liquid used in Test Examples 15 and 17 is 100 parts by mass for Carbodilite SV02 and 1900 parts by mass for water, and corresponds to Test Example 8. For these Test Examples 14 and 15, and Test Examples 16 and 17, the initial contact angle θ1 with water immediately after hydrophilization treatment, the contact angle θ2 after initial warm water immersion with water after hot water immersion immersed in warm water at 80 ° C. for 72 hours, After dipping in warm water, heat-resistant heating at 95 ° C. × 4 hours is performed, and when left to cool to room temperature, contact angle θ3 after heat-resistant heating with water after heat-resistant heating, pseudo-initial stage immersed in warm water at 80 ° C. for 12 hours after heat-resistant heating Experimental result of contact angle θ4 after pseudo initial power generation with water in power generation environment, contact angle θ5 after pseudo long time power generation with water in pseudo long power generation environment immersed in warm water at 80 ° C. for 500 hours after heat-resistant heating Is as shown in Table 3 below.

  From Table 3, it can be seen that in Test Examples 14 and 15, the initial contact angle θ1 is smaller than Test Examples 16 and 17, and the contact angle θ3 after heat-resistant heating is much smaller than Test Examples 14 and 15. In Test Examples 14 and 15, both the pseudo-initial power generation contact angle θ4 and the pseudo long-time power contact angle θ5 are substantially equivalent to those of Test Examples 16 and 17, but the initial values of Test Examples 14 and 15 themselves. The contact angle is smaller than the contact angle θ1, and the contact angle is sufficiently low during long-time power generation.

  INDUSTRIAL APPLICABILITY The present invention can be practically used for a fuel cell carbon separator and can maintain good hydrophilicity for a relatively long time immediately after power generation.

It is sectional drawing which shows the dripping experiment example of the water which shows the hydrophilic degree in the carbon separator surface by the surface treatment using the hydrophilic treatment composition of embodiment of this invention. It is sectional drawing which shows the dripping initial state of the water which shows the experiment example of the water drainage property in the separator flow path of the separator. FIG. 3 is a cross-sectional view showing a state in which wetting of a separator channel is spreading while being lifted by a dropping nozzle in which water dropped after 1 second has elapsed from the state of FIG. 2. FIG. 4 is a cross-sectional view illustrating a state in which water released from the nozzle after another one second has elapsed from the state of FIG. 3 and spread in the longitudinal direction of the separator channel. FIG. 5 is a cross-sectional view showing a state in which a capillary flow in which water further spreads in the longitudinal direction of the separator flow path and further flows away in the longitudinal direction of the separator flow path after one second has elapsed from the state of FIG. . It is sectional drawing which shows the dripping experiment example of the water which shows the hydrophilic degree in the carbon separator which is not surface-treated. It is a flowchart which shows the manufacturing process of the carbon separator for fuel cells which carried out the inorganic acid process after the hydrophilic treatment of this invention. It is a flowchart which shows the manufacturing process of the carbon separator for fuel cells which does the hydrophilic treatment of this invention and does not perform an inorganic acid process.

Explanation of symbols

1 Carbon separator for fuel cell 2 Gas flow path 3 Nozzle 4 Water

Claims (10)

  A separator for a fuel cell, characterized in that an aqueous solution of a hydrophilic treatment composition containing a water-soluble and / or water-dispersible carbodiimide resin or an active ingredient excluding water in a water dispersion is supported on the surface of a gas channel. In the hydrophilic treatment composition,
Furthermore, the quaternary ammonium silicate is contained, The separator for fuel cells of Claim 1 characterized by the above-mentioned. In the hydrophilic treatment composition,
The fuel cell separator according to claim 1, further comprising a silane coupling agent. In the hydrophilic treatment composition,
The carbodiimide resin (A) is included in a range of 1 to 100 parts by mass, the quaternary ammonium silicate (B) is included in a range of 0 to 100 parts by mass, and the silane coupling agent (C) is included in a range of 0 to 10 parts by mass. The fuel cell separator according to claim 1.   The fuel cell separator according to any one of claims 1 to 4, wherein the surface of the gas flow path after supporting the active ingredient is treated with an inorganic acid.   An aqueous solution or aqueous dispersion of a hydrophilic treatment composition containing a water-soluble and / or water-dispersible carbodiimide resin is coated on the surface of the gas flow path of the separator for a fuel cell and then subjected to a treatment for removing water to make the composition hydrophilic. A method for producing a separator for a fuel cell, comprising a hydrophilization treatment step for supporting an active ingredient excluding water in a product on a gas flow path surface. In the hydrophilic treatment composition,
Furthermore, the quaternary ammonium silicate is contained, The manufacturing method of the separator for fuel cells of Claim 6 characterized by the above-mentioned. In the hydrophilic treatment composition,
Furthermore, the silane coupling agent is contained, The manufacturing method of the separator for fuel cells of Claim 6 or 7 characterized by the above-mentioned. In the hydrophilic treatment composition,
The carbodiimide resin (A) is included in a range of 1 to 100 parts by mass, the quaternary ammonium silicate (B) is included in a range of 0 to 100 parts by mass, and the silane coupling agent (C) is included in a range of 0 to 10 parts by mass. A method for producing a fuel cell separator according to claim 6.   The fuel cell separator according to any one of claims 6 to 9, further comprising an inorganic acid treatment step in which the surface of the gas channel after supporting the active ingredient is exposed to an inorganic acid for treatment. Manufacturing method.

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