JP2003034751A - Electroconductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high-electroconductive material having excellent molding characteristics which can improve the electroconductivity of a thermoplastic resin and be applied to the separator of a fuel cell and so on. SOLUTION: A resin-molded body, which is excellent both in formability and in electroconductivity, is obtained by combining adequate amounts of a metallic compound (a boride: TiB2 , WB, MoB, CrB, AlB2 , MgB; a carbide: WC; a nitride: TiN; and so on) and carbon nanotube with a fluidity-excellent thermoplastic resin such as PPS, LCP and so on.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive resin composition, and more particularly to a conductive resin composition having a high conductivity which can be used as a separator material for a solid polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In recent years, fuel cells have been attracting attention as a clean energy source or a clean power source that replaces thermal power generation or a gasoline engine. FIG. 2 is a configuration explanatory view for explaining the configuration of the conventional fuel cell disclosed in JP 2001-15131 A, 6 is a separator, 7 is a negative electrode, 8 is an electrolyte plate, 9 is a positive electrode, and 10 and 14 are The groove (recess) provided in the separator is shown. The grooves 10 and 14 are for increasing the contact area between hydrogen and oxygen and the electrode, and play an important role for improving the power generation efficiency.

The conventional fuel cell has the above-described structure, and oxygen O ₂ and hydrogen H ₂ are flowed so as to come into contact with the negative electrode 7 and the positive electrode 9 sandwiched between the electrolyte plates 8, and at the positive electrode 9 side. , An electron is generated by the reaction of the following formula (1) 2H ₂ → 4H ⁺ + 4e ^{− − − −} (1), and on the other hand, on the negative electrode 7 side, the following formula (2) O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O − -(2) produces H ₂ O, and the electrons move from the positive electrode side to the negative electrode side to generate power. Fuel cells are classified into phosphoric acid type, molten carbonate type, high temperature solid electrolyte type, solid polymer electrolyte type, alkaline type, etc. according to the type of electrolyte sandwiched between positive and negative electrodes.
Since hydrogen and air can be used as active materials, and the power generation efficiency is high, phosphoric acid type and molten carbonate type are the mainstream. However, the operating temperature of these fuel cells is as high as about 200 ° C. for the phosphoric acid type and about 650 ° C. for the molten carbonate type, and the separator is also required to have heat resistance at high temperatures.
As the separator material, materials having high heat resistance such as metal, graphite sheet, and glassy carbon are required, and it is necessary to form the groove as described above in these materials, and it is difficult to process and it is difficult to reduce cost. Was an obstacle to the spread.

On the other hand, in recent years, fuel cells of the type called solid polymer electrolyte type have been attracting attention, aiming at the full-scale spread of fuel cells. This solid polymer electrolyte fuel cell is composed of a unit cell in which an electrode plate made of, for example, carbon is arranged with a polymer ion exchange membrane sandwiched, and a separator is further arranged outside the electrode plate. It has the features that it can operate at a lower temperature (70 to 100 ° C) than a battery, is lightweight, has excellent mass productivity, and can be manufactured at low cost. Therefore, the separator can also be formed of a resin molded product using a polymer material such as a thermoplastic resin, and can be manufactured using an injection molding method.
It has an advantage that the cost can be easily reduced. However, since the resin has an electrical insulating property, a significant improvement in conductivity is indispensable for use as a fuel cell separator that requires high conductivity. The conductivity of the resin is usually improved by adding conductive particles such as a conductive filler to the resin. However, when a large amount of the conductive filler is filled, the moldability is deteriorated and the advantage of using the resin disappears. Problem arises. Therefore, a fuel cell separator using a thermoplastic resin has not yet been put to practical use.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can be used as a separator for a fuel cell that requires simultaneously processability into a predetermined shape and high conductivity. The purpose of the present invention is to provide a resin composition.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that a small amount of carbon nanotubes are added after mixing a small amount of conductive particles so as not to impair the moldability of the thermoplastic resin. When injection molding is performed, it was found that high conductivity is imparted by the carbon nanotubes functioning to establish conduction between the conductive particles, and it is possible to simultaneously achieve good moldability and high conductivity that could not be achieved in the past. The present invention, which realizes a functional resin composition, has been reached.

The electrically conductive resin composition according to the present invention comprises electrically conductive particles and carbon nanotubes dispersed in a thermoplastic resin and has a volume resistance value of 500 mΩ · cm or less. Add a small amount of carbon nanotubes and disperse them, and use the carbon nanotubes to establish conduction between the conductive particles, so that high conductivity can be achieved by blending a small amount of conductive particles, so that the moldability of the thermoplastic resin is impaired. Never be Therefore, by injection molding using such a thermoplastic resin, it is possible to obtain a thermoplastic resin composition having high conductivity in an arbitrary shape, and low-cost production of a fuel cell separator is realized.

The conductive resin composition according to the present invention can have a volume resistance value of 20 mΩ · cm or less.

The conductive resin composition according to the present invention may have a structure in which carbon nanotubes are added to the thermoplastic resin in an amount of 2 to 25% by weight.

The conductive resin composition according to the present invention may have a composition containing 10 to 50% by volume of conductive particles.

In the conductive resin composition according to the present invention, the conductive particles can be a non-oxide ceramic.

In the conductive resin composition according to the present invention, the non-oxide ceramic can be composed of at least one material selected from metal borides, metal nitrides and metal carbides.

In the conductive resin composition according to the present invention, the thermoplastic resin is a polyphenylene sulfide resin, a polyphenylene ether resin, a liquid crystal polymer resin, a polystyrene resin, an ABS resin or a polyacetal resin. It can be composed of one material.

[0014]

FIG. 1 is a cross-sectional view showing the constitution of a conductive resin composition according to the present invention, in which a small amount of carbon nanotubes 2 added to a resin 1 is electrically connected between adjacent conductive particles 3. It is shown that good conductivity is imparted to the resin 1 without adding a large amount of conductive particles as in the conventional case for bridging the bonds. In such a conductive resin composition, high conductivity is obtained by adding a small amount of conductive particles, so that the fluidity of the thermoplastic resin is not impaired. Therefore, the thermoplastic resin containing such carbon nanotubes and conductive particles can be molded by an injection molding method, and the conductive resin composition obtained has high conductivity and should be used as a separator for a fuel cell. You can

The thermoplastic resin in the present invention is not particularly limited as long as it has a thermoplasticity applicable to injection molding and the like, and various thermoplastic resins can be used. Among these thermoplastic resins, polyphenylene sulfide-based resins, polyphenylene ether-based resins, liquid crystal polymer-based resins, polystyrene-based resins, ABS-based resins, polyacetal-based resins, and the like can be preferably used in terms of moldability. .

The conductive particles used in the present invention are not particularly limited as long as they are particles having conductivity, and carbon-based conductive material, oxide-based ceramic conductive material, non-oxide-based ceramic particles, etc. are applied. You can
Among these materials, non-oxide ceramic particles are particularly preferable in terms of having high conductivity, and examples of such non-oxide ceramic particles having high conductivity include metal borides, metal nitrides, and metal carbides. Particles can be preferably used. The shape of the conductive particles is not limited to a single spherical shape or an elliptical shape, and may be a shape in which a plurality of particles are connected, or various shapes such as a needle shape or a long shape.

As the carbon nanotubes used in the present invention, commercially available carbon nanotubes can be applied, and for example, single wall carbon nanotubes manufactured by Material Science Co. can be suitably used.

In the conductive resin composition of the present invention, when carbon nanotubes are added to the thermoplastic resin in an amount of 2 to 25% by weight, a volume resistance value of 500 m · Ω or less can be stably obtained by adding a small amount of conductive particles. . In particular, when 7 to 25 wt% is added, a volume resistance value of 20 m · Ω or less is obtained, which is preferable from the viewpoint of obtaining a resin composition having high conductivity.
When the conductive resin is added to the thermoplastic resin containing the carbon nanotubes in an amount of 10 to 50% by volume, preferably 30 to 40% by volume, good fluidity of the thermoplastic resin is not impaired. A conductive resin composition having a predetermined shape can be easily obtained. Furthermore, 7 to 15
The addition of wt% carbon nanotubes and 30 to 40 vol% conductive particles is most preferable in practice because the decrease in fluidity of the thermoplastic resin is suppressed to a minimum.

[0019]

EXAMPLES The conductive resin composition of the present invention will be described below with reference to examples. In the examples, single-wall carbon nanotubes (diameter: 0.
7 to 1 nm, length 2 to 20 μm, hereinafter also referred to as SWCNT). As the thermoplastic resin, polyphenylene sulfide resin "LR-" manufactured by Topren Co., Ltd.
03 "(hereinafter also referred to as PPS), polyphenylene ether resin" Yupiace AH8 "(hereinafter also referred to as PPE) manufactured by Mitsubishi Engineering Plastics Co., Ltd., liquid crystal polymer" Rod Run LC-50 "manufactured by Unitika Co., Ltd.
00 "(hereinafter also referred to as LCP), polystyrene resin" Styron 679R "(hereinafter also referred to as PS) manufactured by Asahi Kasei Corporation, ABS resin" Styrac 190F "(hereinafter also referred to as ABS) manufactured by Asahi Kasei Corporation, Mitsubishi Engineering Plastics Co., Ltd. polyacetal resin "Iupital F40" (hereinafter also referred to as POM) or Mitsubishi Engineering Plastics polybutylene terephthalate resin "Novaduran 5010R"
7 ”(hereinafter also referred to as PBT) was used. Further, as conductive particles, titanium diboride powder (hereinafter also referred to as TiB ₂ ) manufactured by Nippon Shinkin Co., Ltd., chromium diboride (hereinafter C
rB ₂ ) or titanium nitride (hereinafter also referred to as TiN) or Cu powder manufactured by Wako Pure Chemical Industries, Ltd. was used. On the other hand, the kneading of carbon nanotubes and each thermoplastic resin was performed using a Labo Plastomill manufactured by Toyo Seiki Co., Ltd. The conductivity is measured by the 4-probe method using a resistivity meter (Leosta HP MCP-T410) manufactured by Mitsubishi Chemical Corporation, and each sample surface is # 10 before the conductivity is measured.
Polished with sandpaper of No. 00. The durability of each sample was evaluated by immersing it in warm water at 90 ° C. for 2000 hours and measuring changes in weight and conductivity.

Example 1 15 parts by weight of SWCNT described above and 85 parts by weight of PPS were dry-mixed for 15 minutes using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 36 parts by weight of this melt-kneaded product and 64 parts by weight of TiB ₂ powder were similarly added to 32 parts.
By melt-kneading at 0 ° C, cooling and pulverizing,
A resin composition containing about 35% by volume of iB ₂ was obtained. Using this resin composition as a raw material and using an injection molding machine, a size of 100 m
A plate-like test piece with m × 100 mm and a thickness of 2 mm was molded.
When the conductivity of the obtained test piece was measured by the above-mentioned method, it was found that 50
(S / cm) [20 mΩ · cm in terms of volume resistance value], 138 (S / cm) [approximately 7.3 m in terms of volume resistance value]
A high conductivity of Ω · cm] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 2 7 parts by weight of SWCNT described above and 93 parts by weight of PPS were added,
The mixture was dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 35.5 parts by weight of this melt-kneaded product and 64.5 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 35% by volume of TiB ₂ . . Using this resin composition as a raw material, an injection molding machine is used to obtain a size 1
A plate-shaped test piece having a size of 00 mm × 100 mm and a thickness of 2 mm was molded. When the conductivity of the obtained test piece was measured by the above method, a high conductivity of 83.3 (S / cm) [about 12.0 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 3 15 parts by weight of SWCNT and 85 parts by weight of PPE were dry-mixed for 15 minutes using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 33 parts by weight of this melt-kneaded product and 67 parts by weight of TiB2 powder are similarly added to 32 parts by weight.
By melt-kneading at 0 ° C, cooling and pulverizing,
A resin composition containing about 34% by volume of iB ₂ was obtained. Using this resin composition as a raw material and using an injection molding machine, a size of 100 m
A plate-like test piece with m × 100 mm and a thickness of 2 mm was molded.
When the conductivity of the obtained test piece was measured by the above method, a high conductivity of 97.2 (S / cm) [about 10.3 mΩ · cm in terms of volume resistance value] was obtained.
Moreover, when the above-mentioned durability test was performed on this plate-shaped test piece, the weight change of the test piece compared with the initial value was 1%.
Within, the change in conductivity was also within 10%, and it was found that such a conductive resin composition has excellent durability.

Example 4 The above-mentioned 15 parts by weight of SWCNT and 85 parts by weight of LCP were dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 35.4 parts by weight of this melt-kneaded product and 64.6 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 37% by volume of TiB ₂ . .
Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the conductivity of the obtained test piece was measured by the above-described method, a high conductivity of 166.7 (S / cm) [about 6.0 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 5 15 parts by weight of the above SWCNT and 85 parts by weight of PS were added,
The mixture was dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 32.4 parts by weight of this melt-kneaded product and 67.6 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled and then pulverized to obtain a resin composition containing about 34% by volume of TiB ₂ . . Using this resin composition as a raw material, an injection molding machine is used to obtain a size 1
A plate-shaped test piece having a size of 00 mm × 100 mm and a thickness of 2 mm was molded. When the conductivity of the obtained test piece was measured by the method described above, a high conductivity of 130.6 (S / cm) [about 7.7 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 6 15 parts by weight of the above SWCNT and 85 parts by weight of ABS were dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. by a Labo Plastomill. 33.4 parts by weight of this melt-kneaded product and 66.6 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 33% by volume of TiB ₂ . .
Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the conductivity of the obtained test piece was measured by the above-mentioned method, a high conductivity of 131.9 (S / cm) [about 7.6 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 7 15 parts by weight of SWCNT and 85 parts by weight of POM were dry-mixed for 15 minutes by using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 37.4 parts by weight of this melt-kneaded product and 62.6 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 35% by volume of TiB ₂ . .
Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the conductivity of the obtained test piece was measured by the method described above, a high conductivity of 159.7 (S / cm) [about 6.3 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 8 5 parts by weight of SWCNT described above and 95 parts by weight of PPS were added,
The mixture was dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 28.9 parts by weight of this melt-kneaded product and 71.1 parts by weight of CrB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 37% by volume of CrB ₂ . . Using this resin composition as a raw material, an injection molding machine is used to obtain a size 1
A plate-shaped test piece having a size of 00 mm × 100 mm and a thickness of 2 mm was molded. When the conductivity of the obtained test piece was measured by the above-mentioned method, a high conductivity of 94.4 (S / cm) [about 10.6 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 9 5 parts by weight of the above SWCNT and 95 parts by weight of PPS were added,
The mixture was dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 26.1 parts by weight of this melt-kneaded product and 73.9 parts by weight of TiN powder were mixed in the same manner as described above.
By performing melt-kneading at 20 ° C., cooling and pulverizing,
A resin composition containing about 41% by volume of TiN was obtained. Using this resin composition as a raw material and using an injection molding machine, a size of 100 m
A plate-like test piece with m × 100 mm and a thickness of 2 mm was molded.
When the conductivity of the obtained test piece was measured by the method described above, a high conductivity of 127.8 (S / cm) [about 7.8 mΩ · cm in terms of volume resistance value] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Example 10 5 parts by weight of SWCNT described above and 95 parts by weight of PPS were added,
The mixture was dry-mixed for 15 minutes using a mixer and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 32 parts of 12.2 parts by weight of this melt-kneaded product and 87.8 parts by weight of WC powder were similarly added.
By melt-kneading at 0 ° C, cooling and pulverizing, W
A resin composition containing about 38% by volume of C was obtained. Using this resin composition as a raw material, an injection molding machine is used to measure a size of 100 mm ×
A plate-shaped test piece having a thickness of 100 mm and a thickness of 2 mm was molded. When the conductivity of the obtained test piece was measured by the above method, it was 91.7 (S / cm) [about 1 in terms of volume resistance value].
A high conductivity of 0.9 mΩ · cm] was obtained. In addition, when the above-mentioned durability test was performed on this plate-shaped test piece, the change in weight of the test piece compared with the initial value was within 1% and the change in conductivity was within 10%. The composition was found to have excellent durability.

Comparative Example 1 35.1 parts by weight of the above PPS and TiB ₂ powder 64.9
In the same manner, parts by weight were melt-kneaded at 320 ° C., cooled and pulverized to obtain a resin composition containing about 35% by volume of TiB ₂ . Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the above-mentioned durability test was performed on the obtained test piece, the weight change of the test piece as compared with the initial value was within 1%, and the change in conductivity was also within 10%.
There was no problem in durability. However, when the conductivity was measured by the above method, the obtained conductivity was 4
5.6 (S / cm) [Approximately 21.9 mΩ in terms of volume resistance value]
・ Cm] was a low value.

Comparative Example 2 19.3 parts by weight of the above-mentioned PPS and TiB ₂ powder 80.7
In the same manner, parts by weight were melt-kneaded at 320 ° C., cooled and then pulverized to obtain a resin composition containing about 55 vol% of TiB ₂ . An attempt was made to mold the above test piece using this resin composition as a raw material using an injection molding machine, but the flowability was poor and molding was impossible. Therefore, the conductivity measurement and the durability test could not be performed.

Comparative Example 3 30 parts by weight of the above SWCNT and 70 parts by weight of PPS were dry-mixed for 15 minutes using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 36.7 parts by weight of this melt-kneaded product and 63.3 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 35% by volume of TiB ₂ . .
An attempt was made to mold the above test piece using this resin composition as a raw material using an injection molding machine, but the flowability was poor and molding was impossible. Therefore, the conductivity measurement and the durability test could not be performed.

Comparative Example 4 20 parts by weight of SWCNTs and 80 parts by weight of PPS were dry-mixed for 15 minutes using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 58.4 parts by weight of this melt-kneaded product and 41.6 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled, and then pulverized to obtain a resin composition containing about 18% by volume of TiB ₂ . .
Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the above-mentioned durability test was performed on the obtained test piece, the weight change of the test piece compared with the initial value was 1
%, The change in conductivity was also within 10%, and there was no problem in durability. However, when the conductivity was measured by the above method, the obtained conductivity was 2.1 (S /
cm) [about 476.2 mΩ · cm in terms of volume resistance value], which was a considerably low value.

Comparative Example 5 The above-mentioned 15 parts by weight of SWCNT and 85 parts by weight of PBT were dry-mixed for 15 minutes using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 35.9 parts by weight of this melt-kneaded product and 64.1 parts by weight of TiB ₂ powder were similarly melt-kneaded at 320 ° C., cooled and then pulverized to obtain a resin composition containing about 35% by volume of TiB ₂ . .
Using this resin composition as a raw material, a plate-shaped test piece having a size of 100 mm × 100 mm and a thickness of 2 mm was molded using an injection molding machine. When the conductivity of the obtained test piece was measured by the above-mentioned method, a high conductivity of 145.8 (S / cm) [about 6.9 mΩ · cm in terms of volume resistance value] was obtained. However, when the above-mentioned durability test was carried out on this plate-shaped test piece, the weight change of the test piece as compared with the initial value was 1% or more, and the change in conductivity was 10% or more,
It turned out to be a problem with durability.

Comparative Example 6 15 parts by weight of the above SWCNT and 85 parts by weight of PPS were dry-mixed for 15 minutes by using a mixer, and uniformly melt-kneaded at 320 ° C. with a Labo Plastomill. 22.3 parts by weight of this melt-kneaded product and 77.7 parts by weight of copper powder were similarly added to 32 parts by weight.
By melt-kneading at 0 ° C., cooling and pulverizing, C
A resin composition containing about 35% by volume of u was obtained. Using this resin composition as a raw material, an injection molding machine is used to measure a size of 100 mm ×
A plate-shaped test piece having a thickness of 100 mm and a thickness of 2 mm was molded. When the conductivity of the obtained test piece was measured by the method described above, a high conductivity of 127.8 (S / cm) [about 7.8 mΩ · cm in terms of volume resistance value] was obtained. However, when the above-mentioned durability test was performed on this plate-shaped test piece, the weight change of the test piece compared with the initial value was 1%.
As described above, the change in conductivity was 10% or more, and it was found that there was a problem in durability.

The above Examples 1 to 10 and Comparative Examples 1 to 6
The respective experimental conditions and the obtained results are summarized in Table 1 below.

[Table 1]

[0037]

INDUSTRIAL APPLICABILITY As described above, the conductive resin composition according to the present invention comprises conductive particles and carbon nanotubes dispersed in a thermoplastic resin and has a volume resistance value of 500 mΩ · cm or less. Since the carbon nanotubes dispersed in the plastic resin play a role of conducting wiring between the conductive particles, even if a small amount of the conductive particles is mixed, a conductive resin composition having high conductivity in an arbitrary shape is realized. It is a thing. Further, when the volume resistance value is 20 mΩ · cm or less, it can be applied to a member such as a fuel cell separator which is required to have high conductivity, which is preferable.

When carbon nanotubes are added to the thermoplastic resin in an amount of 2 to 25% by weight, the moldability of the resin composition is improved, so that a conductive resin composition having an arbitrary shape can be easily obtained. be able to.

A suitable amount of the electrically conductive particles is 10 to 50% by volume, and the amount of the electrically conductive particles has an arbitrary shape while maintaining good moldability of the resin composition. The resin composition can be easily obtained.

When a non-oxide ceramic is used as the conductive particles, a conductive resin composition having a higher conductivity than that of a carbon-based conductive material or an oxide-based ceramic conductive material can be obtained. .

When the non-oxide-based ceramic is made of at least one of metal boride, metal nitride and metal carbide, the non-oxide-based ceramic has a high conductivity, so that it is electrically conductive. A conductive resin composition having excellent properties and chemically stable can be obtained.

Further, as the thermoplastic resin, polyphenylene sulfide resin, polyphenylene ether resin,
When it is made of at least one of liquid crystal polymer resin, polystyrene resin, ABS resin and polyacetal resin, a conductive resin composition having excellent moldability and high heat resistance can be produced at low cost. Can be easily obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a cross-sectional structure of a conductive resin composition according to the present invention.

FIG. 2 is a configuration explanatory view showing a configuration of a conventional fuel cell.

[Explanation of symbols]

1 resin, 2 carbon nanotubes, 3 conductive particles, 6 separators, 7 negative electrodes, 8 electrolyte plates, 9 positive electrodes, 10 and 14 grooves (recesses) provided in the separators.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/02 H01M 8/02 B 8/10 8/10 F term (reference) 4J002 BC031 BN151 CB001 CF001 CH071 CN011 DA017 DB016 DF016 DK006 FD116 FD117 GQ02 5G301 DA18 DA22 DA24 DA25 DA42 DD10 5H026 AA06 EE05 EE11 EE18 HH05 HH06

Claims (7)

[Claims] 1. A conductive resin composition having conductive particles and carbon nanotubes dispersed in a thermoplastic resin and having a volume resistance value of 500 mΩ · cm or less. 2. The conductive resin composition according to claim 1, wherein the volume resistance value is 20 mΩ · cm or less. 3. The conductive resin composition according to claim 1, wherein the carbon nanotubes are added to the thermoplastic resin in an amount of 2 to 25% by weight. 4. The conductive resin composition according to claim 1, wherein the conductive particles are mixed in an amount of 10 to 50% by volume. 5. The conductive resin composition according to claim 1, wherein the conductive particles are non-oxide ceramics. 6. The conductive resin composition according to claim 5, wherein the non-oxide ceramic is made of at least one material selected from metal borides, metal nitrides and metal carbides. 7. The thermoplastic resin is at least any one of polyphenylene sulfide resin, polyphenylene ether resin, liquid crystal polymer resin, polystyrene resin, ABS resin and polyacetal resin.
The conductive resin composition according to claim 1, which is composed of one material.