JP2006069839A - Glass-like carbon minute powder and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass-like carbon minute powder useful as a catalyst electrode for a fuel cell, a catalyst carrier, various fillers, etc., and its manufacturing method. <P>SOLUTION: This glass-like carbon minute powder has an average particle diameter of not greater than 1 μm and a specific surface area of not smaller than 1,000 m<SP>2</SP>/g. This is manufactured using as a base material a laminated milled paper having an average pore diameter of 50-150 μm and a porosity of 50-80%, wherein the base material is impregnated with a thermosetting resin solution of a thermosetting resin having a residual carbon of not less than 40% dissolved in an organic solvent at a resin concentration of 20-70 wt%, and is cured by heating, then undergoes a sintering carbonizing treatment and an activation treatment in turn or the sintering carbonizing treatment and the activation treatment simultaneously, and the obtained porous glass-like carbon material is pulverized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode material for an electric double layer capacitor, a catalyst electrode and a catalyst carrier of a fuel cell, and also to a glassy carbon fine powder useful as various fillers and a method for producing the same.

  Glassy carbon is generally obtained by molding and curing a thermosetting resin such as phenol resin or furan resin into a predetermined shape and then heating and calcining at 600 to 2000 ° C. in a non-oxidizing atmosphere. It is a unique carbon material with a glassy structure. Then, paying attention to the characteristics such as corrosion resistance, conductivity, and airtightness, practical application has been promoted in a wide range of applications including the electrochemical field.

  This glassy carbon powder is obtained by pulverizing a glassy carbon molded body, but since glassy carbon is extremely hard, it is very difficult to pulverize uniformly or finely. .

Therefore, in Patent Document 1, glassy carbon powder having an average particle size of 1 μm or more and a specific surface area of 200 m ² / g or more and a cured foam of a thermosetting resin are fired in a non-oxidizing atmosphere and pulverized. Or a method for producing a glassy carbon powder having a specific surface area of 200 m ² / g or more, characterized in that the foam is pulverized and then fired. However, Patent Document 1 cannot obtain a glassy carbon powder having an average particle size of less than 1 μm.

  Moreover, the present applicant has a spherical glassy carbon powder having a true specific gravity of 1.0 or more, an average particle size of 0.1 to 100 μm, and a sphericity of 1.2 or less, and a residual carbon ratio of 45% or more. A first curing treatment in which a thermosetting resin initial condensate is adjusted to a microsphere powder having an average particle size of 0.2 to 120 μm and a sphericity of 1.2 or less, and immersed in an acidic liquid at 10 to 50 ° C. for 30 minutes or more; The manufacturing method (patent document 2) which carries out the 2nd hardening process which hold | maintains at 150-300 degreeC in air | atmosphere for 30 minutes or more, and carries out a calcination carbonization process in a non-oxidizing atmosphere was developed and proposed.

  However, since Patent Document 2 is intended for spherical glassy carbon powders that have excellent fluidity and high handling properties, they have a relatively small specific surface area and are not suitable for applications such as catalyst electrodes and catalyst carriers of fuel cells. In addition, since it is almost spherical, it is difficult to pulverize and pulverization becomes more difficult.

Furthermore, in Patent Document 3, a heat volatile material and a foaming agent that generate gas in a temperature range of 150 to 400 ° C. are added to a thermosetting resin, foamed, and the obtained foam is fired in a non-oxidizing atmosphere. There has been proposed a method for producing a carbon powder which is pulverized or pulverized and then fired in a non-oxidizing atmosphere. And it is shown by this manufacturing method that the carbon particle whose average particle diameter is 2-20 micrometers and a specific surface area is 200-800 m < ² > / g is manufactured.

The method of Patent Document 3 is intended to form pores and increase the specific surface area by a gas generated from a heat volatile material such as polyethylene inside the foam during the firing and carbonization of the foam. It is difficult to form and difficult to pulverize, and a specific surface area of 800 m ² / g or more cannot be obtained, and both particle diameter and specific surface area are used as a catalyst electrode or a catalyst carrier of a fuel cell. not enough.
Japanese Patent Laid-Open No. 03-164416 Japanese Patent Laid-Open No. 05-163007 JP 2000-103610 A

  In order to increase the specific surface area, it is conceivable to activate the glassy carbon powder, but generally, a powder like the glassy carbon powder is activated uniformly and efficiently in the activation gas. It is difficult to do.

  Therefore, as a result of intensive studies to solve these problems, the inventors laminated papermaking paper having a specific porous shape in a desired shape, and impregnated this laminate with a thermosetting resin. A porous glassy carbon molded body obtained by heat-curing and then calcined by carbonization has low strength and can be finely pulverized. Further, when activated and pulverized, it is a glass having a high specific surface area and a small particle diameter. It has been found that fine powder of carbon can be obtained.

  That is, the present invention has been completed based on this finding, and its purpose is glassy carbon useful as an electrode material for electric double layer capacitors, catalyst electrodes and catalyst carriers of fuel cells, and further as various fillers. It is in providing the fine powder and its manufacturing method.

The glassy carbon fine powder according to the present invention for achieving this object is characterized in that the average particle diameter is 1 μm or less and the specific surface area is 1000 m ² / g or more.

  The first production method according to the present invention for vitreous carbon fine powder having the above-mentioned characteristics is a base material obtained by laminating papermaking paper having a porous shape with an average pore diameter of 50 to 150 μm and a porosity of 50 to 80%, The base material is impregnated with a thermosetting resin solution having a resin concentration of 20 to 70 wt% obtained by dissolving a thermosetting resin having a residual carbon ratio of 40% or more in an organic solvent, and then heated and cured in a non-oxidizing atmosphere. It is characterized in that it is calcined and calcined, and then heated to a temperature of 600 to 1500 ° C. in an activation gas atmosphere for activation treatment, and the resulting porous glassy carbon material is pulverized.

  Further, the second production method is a method in which a papermaking paper having a porous shape with an average pore diameter of 50 to 150 μm and a porosity of 50 to 80% is laminated as a base material, and the residual carbon ratio is 40% or more on the base material. After impregnating a thermosetting resin solution having a resin concentration of 20 to 70 wt% in which a thermosetting resin is dissolved in an organic solvent and heating and curing, heating to a temperature of 600 to 1500 ° C. in an activation gas atmosphere to perform a calcination carbonization treatment The activation treatment is performed simultaneously, and the obtained porous glassy carbon material is pulverized.

  The glassy carbon fine powder having a small average particle diameter and a large specific surface area provided by the present invention is used for various applications including, for example, electrode materials for electric double layer capacitors, catalyst electrodes and catalyst carriers of fuel cells. It is extremely useful as various fillers. And this glassy carbon fine powder is impregnated with a thermosetting resin liquid based on a laminate of papermaking paper having a specific porous shape, heat-cured, and then sequentially subjected to calcination carbonization treatment and activation treatment, Alternatively, it is possible to manufacture by subjecting to calcination carbonization and activation treatment at the same time and pulverizing.

  The electrode material for the electric double layer capacitor, the catalyst electrode of the fuel cell, and the catalyst carrier are required to have a porous property because of their functions. For example, the catalyst electrode of the fuel cell has fine pores serving as a reaction gas passage. A porous property is required. Also, a large reaction area is required for the reaction gas to react efficiently on the electrode surface carrying the catalyst.

  That is, in order for the reaction gas to flow smoothly and evenly through the catalyst electrode and the catalyst carrier, and further react quickly at the electrode surface and continue the cell reaction smoothly, the fine pore diameter and specific surface area of the catalyst electrode and catalyst carrier Is greatly involved.

Therefore, the glassy carbon fine powder of the present invention has a mean particle size of 1 μm or less and a specific surface area of 1000 m ² / g or more as a particle property that can be suitably used as a raw material for producing a catalyst electrode of a fuel cell, for example. Is set to The average particle diameter is a value measured by a laser diffraction method, and the specific surface area is a value measured by a BET method.

  In the first production method according to the present invention for producing this glassy carbon fine powder, a papermaking paper having an average pore diameter of 50 to 150 μm and a porosity of 50 to 80% is laminated as a base material, The base material is impregnated with a thermosetting resin solution having a resin concentration of 20 to 70 wt% obtained by dissolving a thermosetting resin having a residual carbon ratio of 40% or more in an organic solvent, and then heated and cured in a non-oxidizing atmosphere. It is characterized in that it is calcined and calcined, and then heated to a temperature of 600 to 1500 ° C. in an activation gas atmosphere for activation treatment, and the resulting porous glassy carbon material is pulverized.

  For the papermaking paper used as the base material, paper made from raw materials such as pulp, rayon and vinylon is used, preferably rayon grade pulp or rayon. Specifically, papermaking paper obtained by mixing 60 to 90 parts by weight of rayon pulp and 40 to 10 parts by weight of softwood pulp having a single characteristic of 3.3 to 11 decitex in thickness and about 5 to 30 mm in length, α-cellulose Paper made by continuous paper making of dispersed water in which 60 to 90 parts by weight of an organic substance containing as a main component, 10 to 40 parts by weight of a water-soluble papermaking binder, and 1 to 10 parts by weight of a water-insoluble and heat-volatile binder are dispersed in water. Etc. are preferably used.

  The papermaking paper thus produced is selectively used with a porosity of 50 to 150 μm in average pore diameter and 50 to 80% porosity. When the average pore diameter is 50 μm and the porosity is less than 50%, the pores are easily blocked when impregnated with the thermosetting resin liquid, and the uniform activation reaction is difficult to proceed because the uniform diffusion of the activation gas is inhibited. It is to become. Further, when the average pore diameter exceeds 150 μm and the porosity exceeds 80%, it is difficult to efficiently impregnate the thermosetting resin. Papermaking paper having such a porous state is laminated to a desired thickness, and if necessary, a compression treatment is performed to obtain a base material. In addition, if papermaking paper is preheated to a temperature of about 50 to 110 ° C. to remove the contained water and modify the surface, it improves the wettability with the resin liquid when impregnated with the resin liquid. Can do.

  The base material on which the papermaking paper is laminated is impregnated with a thermosetting resin liquid. As the thermosetting resin, one having a residual carbon ratio of 40% or more is used. The residual carbon ratio refers to the weight ratio of carbon remaining when the resin is heat-treated at a temperature of 1000 ° C. in a non-oxidizing atmosphere, and if this is less than 40%, the productivity is low and impractical. . Examples of such thermosetting resins include phenol resins, furan resins, polyimide resins, urea resins, melamine resins, and unsaturated polyester resins.

  These thermosetting resins are dissolved in a commonly used organic solvent such as alcohol and acetone to prepare a thermosetting resin liquid. It is necessary to set the resin concentration of the thermosetting resin liquid to 20 to 70 wt%. If the resin concentration is less than 20 wt%, the amount of impregnation of the thermosetting resin decreases, and the yield of glassy carbon decreases. On the other hand, if the resin concentration exceeds 70 wt%, impregnation into the pores of the substrate cannot be performed smoothly. This is because pore clogging is likely to occur, and the uniform activation reaction is difficult to proceed because the uniform diffusion of the activation gas is inhibited. In addition, the impregnation of the thermosetting resin liquid into the substrate is performed by an appropriate method such as dipping or coating.

  The thermosetting resin liquid impregnated in the substrate is heated to remove the organic solvent and harden the resin component. The heat curing treatment is preferably performed by slowly raising the temperature, for example, by heating to a temperature of about 140 ° C. in 6 hours. In this way, a molded body filled with the cured resin is obtained in the pores of the substrate.

  This molded body is transferred to a firing furnace and subjected to heat treatment in a non-oxidizing atmosphere such as nitrogen and argon by a conventional method to perform firing carbonization. During this calcination carbonization, the resin component is converted to glassy carbon, and part of the paper component of the base material is volatilized and part of it remains as a fibrous carbide, giving a molded body that exhibits a certain degree of porosity as a whole. It is done. That is, in this molded body, the fibrous carbides converted and remained from a part of the papermaking paper function as a skeleton of the molded body, so that a molded body having sufficient strength can be obtained while being porous.

  Next, the fired and carbonized molded body is activated by heat treatment in an activation gas atmosphere such as water vapor or carbon dioxide. The heat treatment is activated in a temperature range of 600 to 1500 ° C. to form a porous structure.

Since the glassy carbon material having a porous structure thus obtained is weakened in strength, it can be easily pulverized, and can be finely pulverized by an appropriate pulverizer such as a ball mill. And it becomes possible to manufacture the glassy carbon fine powder whose average particle diameter is 1 micrometer or less and whose specific surface area is 1000 m < ² > / g or more.

  In addition, the second production method according to the present invention for producing the glassy carbon fine powder includes a base material obtained by laminating papermaking paper having a porous shape with an average pore diameter of 50 to 150 μm and a porosity of 50 to 80%. The base material is impregnated with a thermosetting resin solution having a resin concentration of 20 to 70 wt% in which a thermosetting resin having a residual carbon ratio of 40% or more is dissolved in an organic solvent and heat-cured, and then 600 in an activated gas atmosphere. It is characterized in that it is heated to a temperature of ˜1500 ° C. and simultaneously subjected to calcination carbonization treatment and activation treatment, and the resulting porous glassy carbon material is finely pulverized.

  That is, the second manufacturing method performs the firing carbonization treatment and the activation treatment at the same time in the above-described first manufacturing method, and simplifies the manufacturing process.

  Hereinafter, although the Example of this invention is described concretely compared with a comparative example, this invention is not restrict | limited to this Example.

Example 1
80 parts by weight of rayon grade pulp (manufactured by Daiwabo Co., Ltd.) having an α-cellulose content of 90% or more, a thickness of 5.5 dtex, and a length of 5 mm was mixed with 20 parts by weight of bleached softwood pulp (NBKP) and dispersed in water. After that, paper was made using a long net paper machine. The obtained paper-making paper having an average pore diameter of 110 μm and a porosity of 50% was cut into a square having a side of 900 mm, and laminated with the vertical and horizontal directions alternately perpendicular to each other to prepare a substrate.

This base material is immersed in a phenol resin solution having a resin concentration of 50 wt% in which a phenol resin (Sumitrite Dures Co., Sumitrite Resin PR940) having a residual carbon ratio of 45% is dissolved in ethanol, impregnated with the phenol resin solution, and then dried. After being put in a machine and kept at a temperature of 60 ° C. for 2 hours to evaporate and remove ethanol, it is heated while being pressurized at a pressure of 0.5 kg / cm ² , and 140 ° C. at a temperature rising rate of 80 ° C. to 20 ° C./hr. To cure the phenolic resin.

  The molded body after curing is placed in a firing furnace maintained in a nitrogen gas atmosphere, subjected to firing carbonization treatment at a temperature of 1000 ° C., then transferred to an activation furnace, and subjected to activation treatment at a temperature of 950 ° C. in a carbon dioxide atmosphere. A porous glassy carbon molded body was produced. The obtained porous glassy carbon molded body was finely pulverized for 12 hours with a ball mill to produce glassy carbon fine powder.

Example 2
80 parts by weight of rayon grade pulp (manufactured by Daiwa Boseki Co., Ltd.) having an α-cellulose content of 90% or more, a thickness of 5.5 dtex, and a length of 25 mm, and 20 parts by weight of bleached softwood pulp (NBKP) and a water-insoluble and heat-volatile binder As follows, 1 part by weight of vinylon binder (manufactured by Kuraray Co., Ltd., VPB105) was stirred and mixed in water to be uniformly dispersed, then formed into a continuous sheet using a continuous paper machine and dried.

  The obtained continuous sheet having an average pore diameter of 110 μm and a porosity of 60% is set in a continuous resin dipping device, and 20 wt% of phenol resin (Sumitomo Dures Co., Sumitrite Resin PR940) having a residual carbon ratio of 45% through a guide roll. The solution was continuously passed through a tank filled with a% acetone solution, impregnated with a phenol resin solution, and subsequently subjected to a roll squeezing treatment between two rolls adjusted to a gap of 0.2 mm.

  Next, the continuous sheet was passed through a dryer maintained at 100 ° C., and the resin was semi-cured, then cut into a square of 900 mm on each side and laminated, and the compression rate was 65% on a 120 ° C. adjusted soaking platen. The resin was completely cured by compression until

  The cured molded body was put in an activation furnace, heated to a temperature of 950 ° C. in a carbon dioxide atmosphere, and subjected to firing carbonization treatment and activation treatment at the same time to produce a porous glassy carbon molded body. The obtained porous glassy carbon molded body was finely pulverized for 12 hours with a ball mill to produce glassy carbon fine powder.

Comparative Example 1
A phenol resin (Sumitomo Durez, Sumilite Resin PR940) was subjected to suspension polymerization for 3 hours in a 1N aqueous hydrochloric acid solution to which 1% polyvinyl alcohol was added to prepare a resin powder. The obtained resin powder was immersed in a 12N aqueous hydrochloric acid solution to perform a first curing treatment, and subsequently heated in the atmosphere to perform a second curing treatment. Subsequently, the resin powder after the curing treatment was placed in a firing furnace maintained in a nitrogen gas atmosphere, and subjected to firing carbonization treatment at a temperature of 1000 ° C. to produce a glassy carbon powder.

Comparative Example 2
Phenol resin (Sumilite Resin PR940, manufactured by Sumitomo Durez Co., Ltd.) is poured into a mold, cured and molded, and the resulting molded product is placed in a firing furnace maintained in a nitrogen gas atmosphere and calcined at a temperature of 1000 ° C. To obtain a plate-like glassy carbon molded body.

  This glassy carbon molded body was cut into a cube having a side of 10 mm and roughly pulverized by a Nara type pulverizer. The coarsely pulverized glassy carbon was further pulverized with a ball mill for 12 hours to produce a glassy carbon powder.

Comparative Example 3
The glassy carbon powder obtained in Comparative Example 1 was subjected to an activation treatment at a temperature of 950 ° C. in a carbon dioxide atmosphere.

Comparative Example 4
In Example 2, a continuous sheet having an average pore diameter of 40 μm and a porosity of 60% was prepared by changing the length of rayon grade pulp to 20 mm, and a phenol resin solution having a resin concentration of 50 wt% in which phenol resin was dissolved in acetone was used. Others produced glassy carbon fine powder by the same method as Example 2.

Comparative Example 5
Glassy carbon fine powder was produced by the same method as in Example 2 except that the resin concentration of the impregnated phenol resin was changed to 80 wt%.

  The average particle diameter and specific surface area of these glassy carbon powders were measured, and the results are shown in Table 1 in comparison with the production conditions.

Claims (3)

Glassy carbon fine powder having an average particle diameter of 1 μm or less and a specific surface area of 1000 m ² / g or more. Laminated paper-making paper having an average pore diameter of 50 to 150 μm and porosity of 50 to 80% is used as a base material, and a thermosetting resin having a residual carbon ratio of 40% or more is dissolved in the base material in an organic solvent. After impregnating the thermosetting resin liquid having a resin concentration of 20 to 70 wt% and heat-curing, it is heated and calcined in a non-oxidizing atmosphere, and then heated to a temperature of 600 to 1500 ° C. in an activated gas atmosphere. The glassy carbon fine powder is produced by pulverizing the resulting porous glassy carbon material. Laminated paper-making paper having an average pore diameter of 50 to 150 μm and porosity of 50 to 80% is used as a base material, and a thermosetting resin having a residual carbon ratio of 40% or more is dissolved in the base material in an organic solvent. Obtained by impregnating a thermosetting resin liquid having a resin concentration of 20 to 70 wt% and heat-curing, heating to a temperature of 600 to 1500 ° C. in an activation gas atmosphere, and simultaneously performing a calcination carbonization treatment and an activation treatment. A method for producing glassy carbon fine powder, wherein the porous glassy carbon material is finely pulverized.