WO2019189284A1 - Matériau composite et procédé pour sa production - Google Patents

Matériau composite et procédé pour sa production Download PDF

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Publication number
WO2019189284A1
WO2019189284A1 PCT/JP2019/013052 JP2019013052W WO2019189284A1 WO 2019189284 A1 WO2019189284 A1 WO 2019189284A1 JP 2019013052 W JP2019013052 W JP 2019013052W WO 2019189284 A1 WO2019189284 A1 WO 2019189284A1
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Prior art keywords
graphite
composite material
resin
polymer
exfoliated graphite
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PCT/JP2019/013052
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English (en)
Japanese (ja)
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尚代 河▲崎▼
和田　拓也
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積水化学工業株式会社
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Priority to JP2019519336A priority Critical patent/JPWO2019189284A1/ja
Publication of WO2019189284A1 publication Critical patent/WO2019189284A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds

Definitions

  • the present invention relates to a composite material containing exfoliated graphite and a resin, and a method for producing the composite material.
  • Patent Document 1 discloses a composite material containing exfoliated graphite and a resin.
  • a composition containing graphite or primary exfoliated graphite and a polymer, in which the polymer is fixed to graphite or primary exfoliated graphite is prepared.
  • the polymer contained in the prepared composition is thermally decomposed to peel off the graphite or primary exfoliated graphite while leaving a part of the polymer.
  • Patent Document 1 describes that in the step of preparing the composition, a composition containing a thermally decomposable foaming agent may be prepared.
  • An object of the present invention is to provide a composite material having excellent conductivity and a method for producing the composite material.
  • the composite material according to the present invention is a composite material containing exfoliated graphite and a resin, and the ratio (A)% of the resin in the surface of the composite material and the ratio of the resin in the entire composite material ( B)
  • the ratio (A / B) to% by weight is 1.0 or less.
  • the ratio (A)% of the resin in the surface of the composite material is 40.0% or less.
  • the ratio (B) wt% of the resin in the entire composite material is 2.0 wt% or more and 80.0 wt% or less.
  • the exfoliated graphite is a partially exfoliated graphite having a graphite structure and a structure in which the graphite is partially exfoliated.
  • a method for producing a composite material according to the present invention is a method for producing a composite material according to the present invention, comprising graphite or primary exfoliated graphite and a polymer, wherein the polymer is converted into the graphite or primary exfoliated graphite.
  • a step of preparing a fixed composition a first heating step of heating the composition at a temperature of 50 ° C. to 600 ° C. in an inert gas atmosphere, and the first heating step. After that, the composition is heated at a temperature of 300 ° C. or more and 600 ° C. or less in an atmosphere having an inert gas concentration of 85% or more and 99% or less and an oxygen concentration of 1% or more and 15% or less.
  • a second heating step wherein in the first heating step and the second heating step, the polymer in the composition is thermally decomposed to leave a part of the polymer while the graphite or one To peel off the flake graphite.
  • FIG. 1 is a schematic cross-sectional view for explaining how to obtain the ratio (A)% of the resin in the surface of the composite material.
  • FIG. 2 is a field emission scanning electron microscope (FE-SEM) photograph of the composite material obtained in Example 1 at a magnification of 20,000 times.
  • FIG. 3 is a field emission scanning electron microscope (FE-SEM) photograph of the composite material obtained in Comparative Example 1 at a magnification of 20,000 times.
  • FIG. 4 is a schematic diagram for explaining how to obtain the conductivity.
  • the composite material according to the present invention includes exfoliated graphite and a resin.
  • exfoliated graphite and a resin are combined.
  • at least a part of the resin may be carbonized.
  • the ratio (A / B) of the ratio (A)% of the resin occupying the surface of the composite material to the ratio (B) wt% of the resin occupying the entire composite material is 0.0 or more, 1 0.0 or less.
  • the ratio (A)% of the resin occupying the surface of the composite material means the ratio of the portion where the resin is present on the surface of the composite material when the entire surface of the composite material is 100%.
  • the ratio (A)% of the resin occupying the surface of the composite material can be obtained by observing with a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • FE-SEM field emission scanning electron microscope
  • the cross section of the composite material sample is observed.
  • the composite material can be cut into a cross-section of the sample by a cross section Polinshire (manufactured by JEOL Ltd., product number “IB-09010CP”).
  • the cross section of the obtained sample is, for example, using FE-SEM (manufactured by Hitachi, Ltd., product number “S-4800”), acceleration voltage: 3 kV, signal: LA (Upper), and magnification: 20,000 times It can be measured under conditions.
  • the length of the outermost surface portion of the sample and the outermost surface portion are covered with the resin by distinguishing the graphite portion and the resin portion from the contrast obtained by the special signal.
  • the length of the part can be measured.
  • the ratio (A)% of the resin in the surface of the composite material can be determined from the ratio of the length of the portion covered with the resin in the outermost surface portion to the obtained length of the outermost surface portion.
  • FIG. 1 is a schematic cross-sectional view for explaining how to obtain the ratio (A)% of the resin in the surface of the composite material. 1 can be observed under a specific condition of the FE-SEM after preparing a cross section of a sample of a composite material sample using the cross section polisher. Further, the cross-sectional view as shown in FIG. 1 can be observed by using the special signal that allows the composition to be seen. Specifically, exfoliated graphite and resin can be distinguished from the contrast obtained with a special signal.
  • X is a portion where exfoliated graphite 2 is exposed on the surface.
  • X is described in two places, but the total of these is defined as a portion X where exfoliated graphite 2 is exposed on the surface.
  • Y is a portion where the resin 3 is exposed on the surface. Therefore, Y is a portion excluding X on the outer peripheral edge 1 a (surface) of the composite material 1.
  • the ratio (A)% of the resin 3 occupying the surface of the composite material 1 can be obtained from the following formula (1).
  • the ratio (B) wt% of the resin in the entire composite material can be obtained by thermal analysis measurement.
  • the thermal analysis measurement can be performed using, for example, a differential thermothermal gravimetric simultaneous measurement apparatus (product name “TG / DTA6300”, manufactured by SII Nano Technology). Separating the combustion temperature of exfoliated graphite and resin from the differential thermal analysis result obtained using such a differential thermothermal weight simultaneous measurement device, and the ratio of the resin to the entire composite material from the associated thermogravimetric change (B) % By weight can be determined.
  • exfoliated graphite and a resin are combined, so that, for example, when used as an electrode forming slurry of an electricity storage device, dispersibility in the electrode forming slurry can be improved.
  • exfoliated graphite and resin are compounded, aggregation and restacking can be suppressed, and thereby a decrease in conductivity can be suppressed.
  • the ratio (A / B) of the ratio (A)% of the resin occupying the surface of the composite material and the ratio (B) wt% of the resin occupying the entire composite material is within the above range. Since the ratio of the resin occupying the surface is reduced, the degree of exposure of exfoliated graphite is increased, and the conductivity can be effectively increased.
  • the ratio (A / B) is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.4 or less.
  • the lower limit of the ratio (A / B) is not particularly limited, but the ratio (A / B) is preferably 0.01 or more, more preferably 0.1 or more, from the viewpoint of further increasing the conductivity of the composite material. It is.
  • the ratio (A)% of the resin occupying the surface of the composite material is preferably 30.0% or less, more preferably 21.0% or less.
  • the conductivity can be further enhanced. Note that the resin may not be present on the surface of the composite material.
  • the ratio (B) wt% of the resin in the entire composite material is preferably 30.0 wt% or more, more preferably 50.0 wt% or more, preferably 70.0 wt% or less. Preferably it is 60.0 weight% or less.
  • the ratio (B)% by weight of the resin in the whole is not less than the above lower limit, the specific surface area of the composite material can be further increased.
  • the ratio (B)% by weight of the resin in the entire composite material is not more than the above upper limit, the conductivity can be further enhanced.
  • Exfoliated graphite is obtained by exfoliating the original graphite, and refers to a graphene sheet laminate that is thinner than the original graphite.
  • the number of graphene sheets laminated in exfoliated graphite should be less than the original graphite.
  • the number of graphene sheets stacked is preferably 1000 layers or less, more preferably 500 layers or less.
  • the specific surface area of exfoliated graphite can be further increased.
  • the exfoliated graphite is preferably partially exfoliated graphite having a graphite structure and a structure in which the graphite is partially exfoliated.
  • partially exfoliated graphite means that in the graphene laminate, the graphene layer is open from the edge to some extent inside, that is, a part of the graphite is exfoliated at the edge. In the central part, the graphite layer is laminated in the same manner as the original graphite or primary exfoliated graphite. Therefore, the part where the graphite is partially peeled off at the edge is continuous with the central part. Further, the partially exfoliated exfoliated graphite may include one exfoliated and exfoliated from the edge graphite.
  • the graphite layer is laminated in the central portion in the same manner as the original graphite or primary exfoliated graphite. Therefore, the degree of graphitization is higher than that of conventional graphene oxide and carbon black, and the conductivity can be further increased.
  • Such partially exfoliated exfoliated graphite includes graphite or primary exfoliated graphite and a polymer, and a composition in which the polymer is fixed to the graphite or primary exfoliated graphite by grafting or adsorption is prepared and thermally decomposed. Can be obtained.
  • a part of polymer, ie, resin, contained in the composition remains. That is, a resin-retained partially exfoliated graphite is preferable.
  • partially exfoliated graphite from which the resin (polymer) has been completely removed may be used.
  • the graphite used as a raw material is a laminate of a plurality of graphene sheets.
  • the graphite used as a raw material is preferably expanded graphite. Expanded graphite can be easily peeled off because the interlayer of the graphene layer is larger than that of normal graphite. Therefore, by using expanded graphite as the raw material graphite, it is possible to easily produce a resin-retained partially exfoliated exfoliated graphite.
  • the number of graphene layers is about 100,000 to 1,000,000, and the BET specific surface area has a value of 20 m 2 / g or less.
  • the number of graphene layers is preferably 3000 or less.
  • the BET specific surface area of the resin-retained partially exfoliated graphite is preferably 50 m 2 / g or more, and more preferably 70 m 2 / g or more.
  • the upper limit of the BET specific surface area of the resin-retained partially exfoliated graphite is usually 2500 m 2 / g or less.
  • primary exfoliated graphite may be used instead of graphite.
  • Examples of primary exfoliated graphite include exfoliated graphite obtained by exfoliating graphite by a conventionally known method, partially exfoliated graphite, and resin-retained partially exfoliated graphite. Since primary exfoliated graphite is obtained by exfoliating graphite, the specific surface area may be larger than that of graphite.
  • the resin contained in the resin-retained partially exfoliated exfoliated graphite is not particularly limited, and examples thereof include polyether resins, polyvinyl resins, and diene resins.
  • the polyether resin include polypropylene glycol, polyethylene glycol, polytetramethylene glycol and the like.
  • the polyvinyl resin include polyglycidyl methacrylate, polyvinyl acetate, polyvinyl butyral, polyacrylic acid, polystyrene, poly ⁇ -methylstyrene, polyethylene, polypropylene, and polyisobutylene.
  • the diene resin include polybutadiene, polyisoprene, and styrene butadiene rubber.
  • the resin contained in the resin-releasable partially exfoliated exfoliated graphite is preferably a resin that easily generates free radicals by thermal decomposition, such as polypropylene glycol, polyethylene glycol, polyglycidyl methacrylate, and polyvinyl acetate. More preferred are polyethers such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol. More preferred is polyethylene glycol.
  • the interlayer distance between the graphene layers is increased and the specific surface area is large.
  • the resin-retained partially exfoliated graphite has a structure in which the central portion has a graphite structure and the edge portion is exfoliated, and thus is easier to handle than conventional exfoliated graphite.
  • Resin-retained partially exfoliated graphite has high dispersibility in other resins because it contains a resin.
  • the other resin is a resin having a high affinity with the resin contained in the resin residual type exfoliated graphite, the dispersibility of the resin residual type partially exfoliated exfoliated graphite in the other resin is further increased. Will be enhanced.
  • the resin is desirably disposed between the graphene layers of the partially exfoliated graphite. But resin may adhere to the surface and edge part of partially exfoliation type exfoliated graphite. Further, it is desirable that the resin is grafted or adsorbed on the partially exfoliated exfoliated graphite.
  • the resin-retained partially exfoliated graphite can be obtained by a production method described in an example of the production method described later, and can be used as it is as an example of the composite material of the present invention.
  • exfoliated graphite and resin may be prepared separately and combined to obtain a composite material.
  • the resin is not particularly limited, and examples thereof include polyether resins, polyvinyl resins, and diene resins.
  • the polyether resin include polypropylene glycol, polyethylene glycol, polytetramethylene glycol and the like.
  • the polyvinyl resin include polyglycidyl methacrylate, polyvinyl acetate, polyvinyl butyral, polyacrylic acid, polystyrene, poly ⁇ -methylstyrene, polyethylene, polypropylene, and polyisobutylene.
  • the diene resin include polybutadiene, polyisoprene, and styrene butadiene rubber.
  • the resin is preferably a resin that easily generates free radicals by thermal decomposition of polypropylene glycol, polyethylene glycol, polyglycidyl methacrylate, polyvinyl acetate, or the like.
  • polyethers such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol. More preferred is polyethylene glycol.
  • the composite material of the present invention may contain other components as long as the effects of the present invention are not impaired.
  • antioxidants examples include additives such as antioxidants, ultraviolet absorbers, metal damage inhibitors, halogenated flame retardants, flame retardants, fillers, antistatic agents, stabilizers, pigments, and dyes.
  • antioxidant examples include phenol, phosphorus, amine, and sulfur.
  • ultraviolet absorber examples include benzotriazole-based or hydroxyphenyltriazine-based.
  • halogenated flame retardant examples include hexabromobiphenyl ether and decabromodiphenyl ether.
  • flame retardant ammonium polyphosphate, trimethyl phosphate, or the like may be used. These additives may be used alone or in combination.
  • a composition including graphite or primary exfoliated graphite and a polymer, and the polymer is fixed to the graphite or primary exfoliated graphite is first prepared.
  • the step of preparing this composition include the following first and second methods for fixing the polymer to graphite or primary exfoliated graphite by grafting the polymer to graphite or primary exfoliated graphite. .
  • First method In the first method, first, a mixture containing graphite or primary exfoliated graphite and a radical polymerizable monomer is prepared as a raw material. Next, the radically polymerizable monomer contained in the mixture is polymerized. Thereby, a polymer in which the radical polymerizable monomer is polymerized in the mixture is generated, and the polymer is grafted to graphite or primary exfoliated graphite.
  • a composition containing graphite or primary exfoliated graphite and a radical polymerizable monomer is prepared.
  • the blending ratio of graphite and radical polymerizable monomer is not particularly limited, but is preferably 1: 1 to 1: 100 by mass ratio. By setting the blending ratio in the above range, it is possible to effectively exfoliate graphite or primary exfoliated graphite and to obtain a composite material more effectively.
  • the method for preparing the composition is not particularly limited, and examples thereof include a method in which a radical polymerizable monomer is used as a dispersion medium and graphite or primary exfoliated graphite is dispersed in the radical polymerizable monomer.
  • a step of producing a polymer in which the radical polymerizable monomer is polymerized in the composition is performed by polymerizing the radical polymerizable monomer contained in the composition.
  • the radical polymerizable monomer generates a free radical.
  • the radical polymerizable monomer undergoes radical polymerization, thereby producing a polymer in which the radical polymerizable monomer is polymerized.
  • the graphite or primary exfoliated graphite contained in the composition has a radical trapping property because it is a laminate of a plurality of graphene layers. Therefore, when a radically polymerizable monomer is co-polymerized in the composition, the free radicals are adsorbed on the edge and surface of the graphene layer of the graphite or primary exfoliated graphite. Therefore, the polymer or radical polymerizable monomer having free radicals generated at the time of polymerization is grafted to the end portion and the surface of the graphene layer of graphite or primary exfoliated graphite.
  • Examples of the method for polymerizing the radical polymerizable monomer include a method in which the composition is heated to a temperature higher than the temperature at which the radical polymerizable monomer spontaneously starts polymerization. By heating the composition to the temperature or higher, free radicals can be generated in the radical polymerizable monomer contained in the composition. Thereby, the polymerization and grafting described above can be carried out.
  • the heating method is not particularly limited as long as the composition can be heated to the temperature or higher, and the composition can be heated by an appropriate method and apparatus. Moreover, in the case of the said heating, you may heat without sealing, ie, a normal pressure. However, it may be sealed and heated.
  • the temperature may be further maintained for a certain time after heating to a temperature equal to or higher than the temperature at which the radical polymerizable monomer spontaneously starts polymerization.
  • the time for maintaining the temperature in the vicinity of the above temperature is preferably in the range of 0.5 hours to 5 hours, although it depends on the kind and amount of the radical polymerizable monomer used.
  • the step of thermally decomposing the polymer is performed while heating the composition to the thermal decomposition temperature of the polymer while leaving a part of the polymer.
  • the thermal decomposition temperature of the polymer means a decomposition end point temperature dependent on TGA measurement. For example, if the polymer is polystyrene, the thermal decomposition temperature of the polymer is about 350 ° C.
  • the thermal decomposition start temperature and the thermal decomposition end temperature of the resin in the composite material obtained by thermal decomposition are higher than the thermal decomposition start temperature and the thermal decomposition end temperature of the resin before the composite, respectively.
  • the heating method is not particularly limited as long as it can be heated to the thermal decomposition temperature of the polymer, and the composition can be heated by an appropriate method and apparatus.
  • the thermal decomposition so that the resin remains can be achieved, for example, by adjusting the heating time. That is, the amount of residual resin can be increased by shortening the heating time. Also, the amount of residual resin can be increased by lowering the heating temperature.
  • the heating temperature and the heating time may be adjusted in the step of heating so that a part of the polymer (resin) remains.
  • the temperature is further increased after heating to a temperature equal to or higher than the thermal decomposition temperature of the polymer. You may maintain for a fixed time.
  • the time for maintaining the temperature in the vicinity of the above temperature is preferably in the range of 0.5 hours to 5 hours, although it depends on the kind and amount of the radical polymerizable monomer used.
  • the heat treatment for producing the polymer and the heat treatment for thermally decomposing the polymer are performed by the same method and apparatus. You may carry out continuously.
  • the polymer is first grafted to graphite or primary exfoliated graphite by heating the polymer in the presence of graphite or primary exfoliated graphite to a temperature in the temperature range of 50 ° C. or higher and 600 ° C. or lower.
  • the polymer obtained in advance is heated to the specific temperature range in the presence of graphite or primary exfoliated graphite.
  • polymer radicals generated by thermally decomposing the polymer can be directly grafted to graphite or primary exfoliated graphite.
  • a radical polymerizable monomer is polymerized in the presence of graphite or primary exfoliated graphite to produce a polymer, and grafting of the polymer onto graphite or primary exfoliated graphite has been attempted.
  • an appropriate pyrolytic radical generating polymer can be used as the polymer of the second method.
  • a polymer of a radical polymerizable monomer such as a vinyl monomer is preferably used.
  • vinyl monomers that is, vinyl group-containing monomers
  • examples of such vinyl monomers include monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and benzyl acrylate.
  • styrene and glycidyl methacrylate are used.
  • the polymer formed by polymerizing the vinyl group-containing monomer include (meth) acrylic acid alkyl ester, polypropylene, polyvinyl phenol, polyphenylene sulfide, polyphenylene ether, and the like.
  • polymers containing halogen elements such as chlorine such as polyvinyl chloride, chlorinated vinyl chloride resin, ethylene fluoride resin, vinylidene fluoride resin, and vinylidene chloride resin can also be used.
  • Ethylene vinyl acetate copolymer (EVA) polyvinyl acetal, polyvinyl pyrrolidone and copolymers thereof can also be used.
  • Polymers obtained by cationic polymerization such as polyisobutylene and polyalkylene ether can also be used.
  • Polyurethane, epoxy resin, modified silicone resin, silicone resin, etc. formed by crosslinking oligomers can also be used.
  • Polyallylamine may be used, and in that case, an amino group can be grafted to graphite or primary exfoliated graphite.
  • Polyvinylphenol or polyphenols may be used, in which case the phenolic OH can be grafted to graphite or primary exfoliated graphite.
  • the phosphate group can be grafted.
  • condensation polymers such as polyester and polyamide may be used.
  • the decomposition product is grafted although the radical concentration obtained at the decomposition temperature is low.
  • a homopolymer of glycidyl methacrylate, polystyrene, polyvinyl acetate, polypropylene glycol, polyethylene glycol, polytetramethylene glycol, polyvinyl butyral, etc. are preferably used.
  • graphite or primary exfoliated graphite can be more effectively exfoliated.
  • a polyether such as polypropylene glycol, polyethylene glycol, or polytetramethylene glycol is more preferable. More preferred is polyethylene glycol.
  • the blending ratio of graphite or primary exfoliated graphite and polymer is not particularly limited, but it is desirable that the weight ratio is 1: 1 to 1:50. By setting the blending ratio within this range, it is possible to more effectively exfoliate graphite or primary exfoliated graphite and effectively obtain a composite material.
  • the graphite or primary exfoliated graphite can be more effectively exfoliated by heating that causes thermal decomposition of the polymer described later.
  • a specific method for preparing the composition is not limited, and examples thereof include a method in which a polymer and graphite or primary exfoliated graphite are put in an appropriate solvent or dispersion medium and heated. .
  • the polymer is grafted to graphite or primary exfoliated graphite by the above heating.
  • this heating temperature it is desirable to set it as the range of 50 to 600 degreeC.
  • the polymer can be effectively grafted onto the graphite.
  • graphite or primary exfoliated graphite can be more effectively exfoliated. The reason for this is considered as follows.
  • Third method As a third method, a method of dissolving or dispersing graphite and a polymer in an appropriate solvent can be mentioned.
  • a solvent tetrahydrofuran, methyl ethyl ketone, toluene, ethyl acetate, ethanol, water, or the like can be used.
  • a composition in which a polymer is adsorbed on graphite or primary exfoliated graphite in a solvent is prepared as the above composition.
  • the method for adsorbing the polymer to graphite or primary exfoliated graphite is not particularly limited. Since the polymer has adsorptivity to graphite, a method of mixing graphite or primary exfoliated graphite with the polymer in the above-described solvent can be used.
  • the polymer adsorption is considered to be due to the interaction between the surface energy of graphite and the polymer.
  • Exfoliation step of graphite or primary exfoliated graphite by thermal decomposition of polymer In any of the first method, the second method, and the third method, after preparing the composition as described above, the polymer contained in the composition is pyrolyzed. Thereby, graphite or primary exfoliated graphite is exfoliated while a part of the polymer remains, and a composite material can be obtained.
  • the composition may be heated to a temperature higher than the thermal decomposition temperature of the polymer. More specifically, it is heated to a temperature higher than the thermal decomposition temperature of the polymer, and the polymer is further baked. At this time, it is fired to such an extent that the polymer remains in the composition.
  • the thermal decomposition temperature of polystyrene is about 380 ° C. to 450 ° C.
  • the thermal decomposition temperature of polyglycidyl methacrylate is about 400 ° C. to 500 ° C.
  • the reason why the composite material can be obtained by thermal decomposition of the polymer is considered to be due to the above-described reason. That is, it is considered that when the polymer grafted on the graphite is baked, a large stress acts on the graft point, thereby increasing the distance between the graphenes.
  • the first method, the second method, and the third method can be appropriately selected and used.
  • the heating in the first heating step is performed in an inert gas atmosphere.
  • the inert gas examples include nitrogen, helium, argon, and carbon dioxide gas.
  • the inert gas is preferably nitrogen.
  • the oxygen concentration is preferably 1% or less, more preferably 0.1% or less. In this case, the defects of exfoliated graphite in the obtained composite material can be further reduced. Therefore, the conductivity of the composite material can be further increased.
  • the composition that has undergone the first heating step is heated at a temperature of 300 ° C. or higher and 600 ° C. or lower.
  • heating time it can be 10 minutes or more and 180 minutes or less, for example.
  • the heating in the second heating step is performed in an atmosphere having an inert gas concentration of 85% to 99% and an oxygen concentration of 1% to 15%.
  • the inert gas examples include nitrogen, helium, argon, and carbon dioxide gas.
  • the inert gas is preferably nitrogen.
  • the inert gas concentration is preferably 90% or more, and preferably 97% or less.
  • the oxygen concentration is preferably 3% or more, preferably 10% or less.
  • the resin on the surface of the composite material obtained can be selectively reduced as described later, and the conductivity of the composite material can be further enhanced.
  • oxygen concentration is below the said upper limit, the defect of exfoliated graphite in the composite material obtained can be decreased further, and the electroconductivity of a composite material can be improved further.
  • the polymer contained in the composition is heated in the first heating step (selected appropriately from the first method, the second method, and the third method).
  • the graphite or primary exfoliated graphite is peeled off while leaving a part of the polymer by thermally decomposing and compositing with graphite, whereby a composite material can be obtained.
  • the defect of exfoliated graphite in the composite material obtained can be decreased. Therefore, the conductivity of the composite material can be increased.
  • heating is performed in an atmosphere in which the inert gas concentration and the oxygen concentration are in the specific ranges, so that the ratio of the resin occupying the surface of the composite material is selectively reduced. Can do. Therefore, also from this point, conductivity can be effectively increased, and battery characteristics such as output characteristics of the electricity storage device can be improved.
  • the resin remains and the specific surface area is increased. Therefore, the capacity of the electricity storage device can be increased, and the battery characteristics can be improved from this point.
  • the electrical conductivity is enhanced by reducing the amount of resin on the surface while increasing the specific surface area by leaving the resin. Therefore, both output characteristics and capacity can be increased by using the electrode material for an electricity storage device or the like.
  • the composite material is obtained by pyrolyzing the polymer in the composition having a structure in which the polymer in which the radical polymerizable monomer is polymerized as described above is grafted to graphite or primary exfoliated graphite. It has gained.
  • the graphite may be further exfoliated as described above by using a composite material as a raw material.
  • you may implement the manufacturing method of the composite material of this invention by using the primary exfoliated graphite obtained by the exfoliation method of the other graphite as a raw material. Even in that case, a composite material having a larger specific surface area can be obtained.
  • a method for exfoliating graphite for example, a method for exfoliating graphite by electrochemical treatment or an adsorption-pyrolysis method can be used.
  • no thermally decomposable foaming agent is used during heating. Therefore, the amount of defects in exfoliated graphite can be reduced, and the conductivity can be further enhanced.
  • a pyrolytic foaming agent may be used during heating.
  • the composite material obtained by the example of the production method of the present invention is the above-mentioned resin-retained partially exfoliated graphite.
  • exfoliated graphite and resin may be prepared separately, and exfoliated graphite and resin may be combined by a method such as kneading to obtain a composite material.
  • Example 1 16 g of expanded graphite (trade name “PF Powder 8” manufactured by Toyo Tanso Co., Ltd.), 48 g of 1% carboxymethylcellulose aqueous solution and 480 g of pure water were mixed, and an ultrasonic crusher (trade name “UH-” manufactured by SMT Co., Ltd.) was mixed. 600S "), and ultrasonic treatment was performed for 5 hours in the intensity memory 6. As a result, a graphite / water dispersion in which graphite was dispersed in water was obtained.
  • PF Powder 8 manufactured by Toyo Tanso Co., Ltd.
  • the composition was heat-dried at a temperature of 150 ° C. for 3 hours to obtain a dried product. Thereafter, the obtained dried product is further heated to a temperature of 370 ° C. under a nitrogen atmosphere (oxygen concentration of 0.1% or less), maintained at a temperature of 370 ° C. for 2 hours, and the first heating step is performed. went. Subsequently, the composition subjected to the first heating step is further heated to a temperature of 400 ° C. in an atmosphere having a nitrogen concentration of 95% and an oxygen concentration of 5%, and is maintained at the temperature of 400 ° C. for 0.5 hour. A second heating step was performed.
  • the polyethylene glycol in the dried product was pyrolyzed, and the expanded graphite was peeled off.
  • a composite material which is a resin-retained partially exfoliated graphite was obtained.
  • FIG. 2 is a field emission scanning electron microscope (FE-SEM) photograph of the composite material obtained in Example 1 at a magnification of 20,000 times.
  • FIG. 3 is a field emission scanning electron microscope (FE-SEM) photograph of the composite material obtained in Comparative Example 1 at a magnification of 20,000.
  • the cross section of the obtained sample was measured using FE-SEM (manufactured by Hitachi, Ltd., product number “S-4800”) under the conditions of acceleration voltage: 3 kV, signal: LA (Upper), and magnification: 20,000 times. It was measured.
  • FIGS. 2 and 3 by observing under such conditions, the exfoliated graphite (graphite) portion and the resin portion were discriminated. Specifically, in FIGS. 2 and 3, the portion that appears white is the graphite portion, and the other gray portion is the resin portion.
  • the composite material that has undergone the second heating step is compared with FIG. 3 of the composition that has undergone only the first heating step (not through the second heating step). It can be seen that the amount of resin on the surface of the exfoliated graphite (graphite) portion is reduced.
  • the length of the outermost surface portion of the sample and the outermost surface portion are covered with the resin by distinguishing the graphite portion and the resin portion from the contrast obtained by the special signal.
  • the length of the part is measured.
  • the ratio (A)% of the resin in the surface of the composite material was determined from the ratio of the length of the portion covered with the resin in the outermost surface portion to the obtained length of the outermost surface portion.
  • the particle outermost surface portion in the cross section was visually observed to be 10 ⁇ m or more, and the graphite portion and the resin portion were distinguished.
  • (A)% was calculated
  • the ratio (A)% of the resin occupying the surface was similarly obtained for Comparative Example 1 that passed through only the first heating step (not passed through the second heating step).
  • the ratio (B) weight% of the resin in the entire composite material was determined by thermal analysis measurement.
  • the thermal analysis measurement was performed using a differential thermothermogravimetric simultaneous measurement device (TG-DTA, differential thermothermal gravimetric simultaneous measurement device (trade name “TG / DTA6300” manufactured by SII Nanotechnology)). Separating the combustion temperature of exfoliated graphite and resin from the differential thermal analysis results obtained using this differential thermothermal weight simultaneous measurement device, and the proportion of the resin in the entire composite material (B) wt% Asked.
  • the ratio (B) wt% of the resin in the entire composition was similarly determined for Comparative Example 1 that passed through only the first heating step (not passed through the second heating step).
  • the ratio (A / B) was determined from the ratio (A)% of the resin occupying the surface and the ratio (B)% by weight of the resin occupying the whole surface. The results are shown in Table 1 below.
  • Example 2 A composite material was obtained in the same manner as in Example 1 except that the heating time in the first heating step was changed from 2 hours to 1 hour.
  • Example 3 A composite material was obtained in the same manner as in Example 1 except that the heating time in the first heating step was changed from 2 hours to 4 hours.
  • Example 4 234 g of polyethylene glycol (trade name “PEG-600” manufactured by Sanyo Kasei Co., Ltd.) is added to 1 g of expanded graphite (trade name “PF Powder 8” manufactured by Toyo Tanso Co., Ltd.), and a homogenizer (trade name “MARK II” manufactured by Primix Co., Ltd.) is added. Graphite and resin were compounded by stirring at 8000 rpm for 30 minutes using Model 2.5 "). In this way, a composition in which polyethylene glycol was adsorbed on expanded graphite was prepared.
  • polyethylene glycol trade name “PEG-600” manufactured by Sanyo Kasei Co., Ltd.
  • expanded graphite trade name “PF Powder 8” manufactured by Toyo Tanso Co., Ltd.
  • a homogenizer trade name “MARK II” manufactured by Primix Co., Ltd.
  • the obtained dried product is further heated to a temperature of 370 ° C. under a nitrogen atmosphere (oxygen concentration of 0.1% or less), maintained at a temperature of 370 ° C. for 1 hour, and the first heating step is performed. went.
  • the composition that has undergone the first heating step is further heated to a temperature of 900 ° C. in a nitrogen atmosphere (oxygen concentration of 0.1% or less) and maintained at a temperature of 900 ° C. for 0.5 hours.
  • a second heating step was performed.
  • the polyethylene glycol in the dried product was pyrolyzed, and the expanded graphite was peeled off. Thereafter, potassium carbonate was removed by washing with water to obtain a composite material that was partially exfoliated graphite.
  • the electrical conductivity of the composite materials of Examples 3 to 4 and Comparative Examples 1 and 2 was measured. The results are shown in Table 1 below.
  • a method for measuring conductivity will be described with reference to FIG. First, as shown in FIG. 4, 1.0 g of the sample 5 was filled in the container 4 including the electrode 6. Next, the electrical resistance value when the sample 5 was compressed at a predetermined pressure was measured through the electrode 6 by the four-probe method. Thereby, the conductivity of the sample was measured. The conductivity was measured using a powder resistance device (Mitsubishi Chemical Corporation, product number: PD-51).

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  • Organic Chemistry (AREA)
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Abstract

La présente invention concerne un matériau composite présentant une excellente conductivité électrique. Un matériau composite qui contient du graphite lamellaire et une résine, et qui est configuré de telle sorte que le rapport de l'occupation (A) % de la résine dans la surface du matériau composite à l'occupation (B) % en poids de la résine dans le matériau composite entier, à savoir A/B soit inférieur ou égal à 1,0.
PCT/JP2019/013052 2018-03-27 2019-03-27 Matériau composite et procédé pour sa production WO2019189284A1 (fr)

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WO2012165372A1 (fr) * 2011-06-03 2012-12-06 積水化学工業株式会社 Matériau composite et son procédé de fabrication
WO2014034855A1 (fr) * 2012-09-03 2014-03-06 積水化学工業株式会社 Matériau composite et son procédé de production
WO2014034156A1 (fr) * 2012-08-27 2014-03-06 積水化学工業株式会社 Matériau composite en paillettes de graphite et résine et procédé de production associé
WO2015098758A1 (fr) * 2013-12-26 2015-07-02 積水化学工業株式会社 Matériau d'électrode de condensateur, son procédé de fabrication et condensateur à double couche électrique
JP2016166352A (ja) * 2015-03-02 2016-09-15 積水化学工業株式会社 薄片化黒鉛・樹脂複合材料の製造方法及び薄片化黒鉛・樹脂複合材料

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WO2012105344A1 (fr) * 2011-02-04 2012-08-09 積水化学工業株式会社 Procédé pour la production de matériau composite de graphite lamellaire-polymère
WO2012165372A1 (fr) * 2011-06-03 2012-12-06 積水化学工業株式会社 Matériau composite et son procédé de fabrication
WO2014034156A1 (fr) * 2012-08-27 2014-03-06 積水化学工業株式会社 Matériau composite en paillettes de graphite et résine et procédé de production associé
WO2014034855A1 (fr) * 2012-09-03 2014-03-06 積水化学工業株式会社 Matériau composite et son procédé de production
WO2015098758A1 (fr) * 2013-12-26 2015-07-02 積水化学工業株式会社 Matériau d'électrode de condensateur, son procédé de fabrication et condensateur à double couche électrique
JP2016166352A (ja) * 2015-03-02 2016-09-15 積水化学工業株式会社 薄片化黒鉛・樹脂複合材料の製造方法及び薄片化黒鉛・樹脂複合材料

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022102693A1 (fr) * 2020-11-13 2022-05-19 積水化学工業株式会社 Auxiliaire conducteur pour batteries secondaires à électrolyte non aqueux, électrode positive pour batteries secondaires à électrolyte non aqueux, et batterie secondaire à électrolyte non aqueux

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