Electroconductive structure, manufacturing method therefor, and separator for fuel cell

Abstract

The present invention provides a method for manufacturing a conductive structure having high electrical conductivity, and a method for manufacturing a dimensionally accurate separator for a fuel cell having high electrical conductivity. In the present invention, the cavity surface temperature of a mold is kept equal to or higher than the crystal melting temperature (T m ) of composite material until the shaping of the composite material melted in the mold is completed, and after the completion of the shaping process, the cavity surface temperature of the mold is controlled to be equal to or higher than a temperature 20° C. lower than the crystallization temperature (T c ) of the composite material but equal to or lower than a temperature 20° C. higher than the crystallization temperature of the composite material to harden the composite material.

1 - 22 . (canceled) 
     
     
         23 . The conductive structure according to  claim 34 , wherein said conductive structure is hardened, cooled and/or heat-treated while pressurized in said mold or while being pressurized in a sandwiched manner between corrective plates for preventing deformation of said conductive structure. 
     
     
         24 . The conductive structure according to  claim 34 , wherein the molding of said conductive structure employs one molding method selected from among injection molding, injection-compression molding, compression molding, and stamping molding. 
     
     
         25 . The conductive structure according to  claim 34 , wherein said crystalline thermoplastic resin composite material further contains an elastomer. 
     
     
         26 . (canceled) 
     
     
         27 . The conductive structure according to  claim 34 , wherein at least one component contained in said crystalline thermoplastic resin is polyolefin. 
     
     
         28 . The conductive structure according to  claim 34 , wherein said polymer component contains at least one of hydrogenated styrene-butadiene rubber, styrene-ethylene/butylene-styrene block copolymer, styrene-ethylene/propylene-styrene block copolymer, olefin crystal-ethylene/butylene-olefin crystal block copolymer, styrene-ethylene/butylene-olefin crystal block copolymer, styrene-isoprene-styrene block copolymer, and styrene-butadiene-styrene block copolymer and polyolefin. 
     
     
         29 . The conductive structure according to  claim 34 , wherein said polymer component contains at least polyvinylidene fluoride and soft acrylic resin. 
     
     
         30 . The conductive structure according to  claim 34 , wherein said conductive filler material contains at least one selected from the group consisting of metallic material, carbonaceous material, conductive polymer, meta-coated filler, and metal oxide, 
     
     
         31 . The conductive structure according to  claim 34 , wherein said conductive filler material contains carbonaceous material containing 0.05 to 5 mass % of boron. 
     
     
         32 . The conductive structure according to  claim 34 , wherein said conductive filler material contains 0.1 to 50 mass % of vapor-grown carbon fiber and/or carbon nanotube based on the total mass of said conductive filler material containing the same. 
     
     
         33 . The conductive structure according to  claim 32 , wherein said vapor-grown carbon fiber or said carbon nanotube contains 0.05 to 5 mass % of boron. 
     
     
         34 . A conductive structure made of crystalline thermoplastic resin composite material containing a polymer component comprising crystalline thermoplastic resin, and conductive filler material, wherein the polymer component accounts for 2 to 40 mass %, while the conductive filler material accounts for 60 to 98 mass % of the total 100 mass % of the polymer component and the conductive filler material, and
 said conductive structure is manufactured by a method wherein when molding the conductive structure, a cavity surface temperature of a mold is kept equal to or higher than a crystal melting temperature (T m ) of said composite material until a shaping of said composite material melted in said mold is completed, and after completion of said shaping process, under the provision that the crystallization temperature of said composite material is represented by T c , the cavity surface temperature of said mold is controlled to be (T c ±20)° C. to harden said composite material, and   the relationship expressed by the formula: X≧0.8×Y (Formula 1) is satisfied,   in Formula 1, X represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when heating a sample that is obtained from said conductive structure from 25° C. to a temperature 60° C. or more higher than the crystal melting temperature (T m ) of said thermoplastic resin composite material at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g,   Y represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when keeping a sample that is obtained from said crystalline thermoplastic resin composite material at a temperature 60° C. or more higher than T m  for 10 minutes, cooling the sample to 25° C. at a cooling rate of 5° C./min to be kept at 25° C. for 10 minutes, and then heating the sample to a temperature 60° C. or more higher than T m  at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g.   
     
     
         35 . A conductive structure made of crystalline thermoplastic resin composite material containing a polymer component comprising crystalline thermoplastic resin, and conductive filler material, wherein the polymer component accounts for 2 to 40 mass %, while the conductive filler material accounts for 60 to 98 mass % of the total 100 mass % of the polymer component and the conductive filler material, and
 said conductive structure is manufactured by a method wherein when molding the conductive structure, after shaping of said composite material melted in a mold is completed, under the provision that a crystallization temperature of said composite material is represented by T c , said composited material is cooled at a cooling rate of 30° C./min or less within a temperature range of (T c ±20)° C., and   the relationship expressed by the formula: X≧0.8×Y (Formula 1) is satisfied,   in Formula 1, X represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when heating a sample that is obtained from said conductive structure from 25° C. to a temperature 60° C. or more higher than the crystal melting temperature (T m ) of said thermoplastic resin composite material at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g,   Y represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when keeping a sample that is obtained from said crystalline thermoplastic resin composite material at a temperature 60° C. or more higher than T m  for 10 minutes, cooling the sample to 25° C. at a cooling rate of 5° C./min to be kept at 25° C. for 10 minutes, and then heating the sample to a temperature 60° C. or more higher than T m  at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g.   
     
     
         36 . A conductive structure made of crystalline thermoplastic resin composite material containing a polymer component comprising crystalline thermoplastic resin, and conductive filler material, wherein the polymer component accounts for 2 to 40 mass %, while the conductive filler material accounts for 60 to 98 mass % of the total 100 mass % of the polymer component and the conductive filler material, and
 said conductive structure is manufactured by a method wherein the molded conductive structure is heat-treated at a temperature equal to or lower than a crystal melting temperature (T m ) of said composite material but equal to or higher than (T m −20)° C., and   the relationship expressed by the formula: X≧0.8×Y (Formula 1) is satisfied,   in Formula 1, X represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when heating a sample that is obtained from said conductive structure from 25° C. to a temperature 60° C. or more higher than the crystal melting temperature (T m ) of said thermoplastic resin composite material at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g,   Y represents a value obtained by dividing the crystal melting heat observed, using a differential scanning calorimeter, when keeping a sample that is obtained from said crystalline thermoplastic resin composite material at a temperature 60° C. or more higher than T m  for 10 minutes, cooling the sample to 25° C. at a cooling rate of 5° C./min to be kept at 25° C. for 10 minutes, and then heating the sample to a temperature 60° C. or more higher than T m  at a heating rate of 20° C./min by the mass of the sample, the unit of which is J/g.   
     
     
         37 . A separator for a fuel cell employing the conductive structure according to  claim 34 . 
     
     
         38 . A separator for a fuel cell employing the conductive structure according to  claim 35 . 
     
     
         39 . A separator for a fuel cell employing the conductive structure according to  claim 36 . 
     
     
         40 . The conductive structure according to  claim 35 , wherein said conductive filler material contains carbonaceous material containing 0.05 to 5 mass % of boron. 
     
     
         41 . The conductive structure according to  claim 36 , wherein said conductive filler material contains carbonaceous material containing 0.05 to 5 mass % of boron.