Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0007—Casings
  • H05K9/002—Casings with localised screening
  • H05K9/0022—Casings with localised screening of components mounted on printed circuit boards [PCB]
  • H05K9/0024—Shield cases mounted on a PCB, e.g. cans or caps or conformal shields
  • H05K9/0031—Shield cases mounted on a PCB, e.g. cans or caps or conformal shields combining different shielding materials
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0073—Shielding materials
  • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
  • H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/182—Graphene
  • C01B32/184—Preparation
  • C01B32/186—Preparation by chemical vapour deposition [CVD]
• • 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
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
  • H05K2201/0203—Fillers and particles
  • H05K2201/0206—Materials
  • H05K2201/0212—Resin particles

Definitions

• the present disclosure relates to electromagnetic interference suppression materials.
• Patent Document 1 there is disclosed a material in which soft magnetic metal powder such as a powder of a metal selected from Fe, Ni, Co and V or an alloy composed of two or more of these metals is dispersed in a rubber or plastic matrix.
• An electromagnetic wave shielding material molded into a sheet shape Patent Document 2 describes a sheet-like sheet-like material in which a radio wave absorbing layer formed by a radio wave absorbing material in which silicon carbide powder is dispersed in a matrix resin is laminated on the surface of a metal body.
• Patent Document 3 discloses a dielectric layer made of a matrix containing a carbon material, a divided conductive film layer laminated on one surface of the dielectric layer, and a laminated conductive film layer laminated on the other surface of the dielectric layer.
• the present disclosure has been made in view of such circumstances, and aims to provide an electromagnetic interference suppression material that has good electromagnetic wave absorption performance, electromagnetic interference suppression performance, and better electromagnetic interference reduction performance.
• an electromagnetic interference suppressing material containing a base material containing at least one selected from organic substances and inorganic substances and a predetermined powdered carbon material has electromagnetic wave absorption performance. And it was found that the electromagnetic interference suppression performance is good, and the electromagnetic interference reduction performance is better.
• the present disclosure has been completed based on such findings.
• An electromagnetic interference suppressing material containing a base material containing at least one selected from organic substances and inorganic substances, and a powdered carbon material,
• the powdered carbon material is at least one selected from a first shell-like body that is a hollow particle having one hole, and a second shell-like body that has a shape in which hollow particles are connected and has a plurality of holes.
• An electromagnetic interference suppressing material wherein the shell portions of the first shell-like body and the second shell-like body are made of graphene having an average number of layers of 4 or less.
• an electromagnetic interference suppressing material that has good electromagnetic wave absorption performance and electromagnetic interference suppression performance, as well as better electromagnetic interference reduction performance.
• XX to YY means “XX or more and YY or less”.
• the lower and upper limits described stepwise for numerical ranges can be independently combined.
• the upper and lower limits of the numerical ranges may be replaced with the values shown in the examples.
• the term “electromagnetic interference suppression material” refers to a material that can attenuate near-field electromagnetic fields and electromagnetic waves by utilizing its loss characteristics (magnetic loss, dielectric loss, electrical resistance, etc.).
• graphene means “a sheet-like material of up to 10 layers of sp2- bonded carbon atoms".
• the specific surface area refers to the BET specific surface area, and is a value obtained by measurement by a BET multipoint method using nitrogen adsorption.
• the term “hollow particle” refers to a particle having a shell and having a cavity inside the particle surrounded by the shell.
• the electromagnetic interference suppression material of the present disclosure includes a base material containing at least one selected from organic substances and inorganic substances, and a powdered carbon material.
• the powdered carbon material is at least selected from a first shell-like body that is a hollow particle having one hole, and a second shell-like body that has a shape in which hollow particles are connected and has a plurality of holes. 1 type, and the shell portions of the first shell-like body and the second shell-like body are made of graphene having an average number of layers of 4 or less.
• the powdered carbon material is at least one selected from the first shell and the second shell, and the shell portions of the first shell and the second shell are By using graphene with an average number of layers of 4 or less, the obtained electromagnetic interference suppressing material has good electromagnetic wave absorption performance and electromagnetic interference suppressing performance, and has better electromagnetic interference reducing performance. Although the reason for this is not clear, it is considered as follows.
• the powdered carbon material of the present disclosure is hollow particles, and the shell of the hollow particles is made of graphene with an average number of layers of 4 or less.
• the powdery carbon material of the present disclosure is a shell-shaped graphene laminate composed of graphene sheets having an average number of three-dimensionally continuous layers of 4 or less. Therefore, the powdered carbon material has a large specific surface area as a carbon material and high radio wave absorption performance per unit volume. Furthermore, the powdered carbon material can improve the volume resistance as compared with the case where the same amount of other carbon material is contained. It is considered that the electromagnetic wave absorption performance and the electromagnetic interference suppression performance are improved by including the powdered carbon material of the present disclosure, which has such a large specific surface area and an effect of improving the volume resistance.
• the shell portions of the first shell-shaped body and the second shell-shaped body have an average number of layers from the viewpoint of increasing the specific surface area of the powdered carbon material and further improving the electromagnetic wave absorption performance and the electromagnetic interference suppression performance. It may be composed of less than 4 graphenes, may be composed of 3 or less graphenes, may be 2.5 or less, may be 2.0 or less, or may be 1.9 or less. may be
• the electromagnetic interference suppression material may have a volume resistance of 10 3 ⁇ cm or more, or 10 6 ⁇ cm or more, from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance. It may be 10 7 ⁇ cm or more. Although the upper limit is not particularly defined, it may be 10 16 ⁇ cm or less.
• the powdered carbon material of the present disclosure may be present in the electromagnetic interference suppressing material, or may be present on the surface of the base material containing at least one selected from the above organic substances and inorganic substances.
• the powdered carbon material of the present disclosure is at least selected from a first shell-like body that is a hollow particle having one hole, and a second shell-like body that has a shape in which hollow particles are connected and has a plurality of holes. It is one type.
• the shell portions of the first shell-like body and the second shell-like body are made of graphene having an average number of layers of 4 or less.
• a first shell-shaped body of the present disclosure is a hollow particle having one hole.
• the average pore diameter of the pores of the first shell-like body may be 0.5 to 100 nm, 0.7 to 50 nm, or 1.0 to 20 nm.
• the average pore diameter of the pores of the first shell-like body and the second shell-like body is a value obtained from the following formula, assuming cylindrical pores.
• Average pore diameter 4 x pore volume/specific surface area (m 2 /g)
• the pore volume is a value per material mass obtained from the adsorption amount at a relative pressure (P/P0) of 0.96 by measuring the nitrogen adsorption isotherm, and the specific surface area is the BET specific surface area. It is a value obtained by measuring by the BET multipoint method by nitrogen adsorption.
• the second shell-shaped body of the present disclosure has a shape in which hollow particles are connected and has a plurality of holes.
• the number of holes that the second shell-like body has may be plural, and there is no particular limitation.
• the average pore diameter of one pore of the second shell may be 0.5 to 100 nm, 0.7 to 50 nm, or 1.0 to 20 nm. .
• the average particle size of the first shell-like body may be considered to be the same as the average pore size of the pores of the first shell-like body described above, because the shell thickness is very thin.
• the average particle size of the second shell-shaped body may be 1.0 nm or more, 2.0 nm or more, or 5.0 nm or more from the viewpoint of ease of production, From the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, the thickness may be 1000 nm or less, 500 nm or less, or 200 nm or less.
• the average particle diameter of the second shell-like bodies can be estimated by using a laser diffraction particle size distribution analyzer.
• the average particle size of the powdered carbon material may be 200 ⁇ m or less from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance.
• the "average particle size of the powdered carbon material” refers to the average particle size of the primary particles when the powdered carbon material is not agglomerated and is primary particles. However, when secondary particles are formed, it refers to the average particle size of the secondary particles.
• the method for measuring the average particle diameter of the powdered carbon material is calculated from the volume and specific surface area of the pores, estimated by a laser diffraction particle size distribution meter, or scanned with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). ) is a value calculated as the average particle size of particles observed in 20 to 100 visual fields.
• the term "particle size” means the maximum distance between any two points passing through the center of the particle and on the contour line of the particle.
• the average particle size (primary particles) of the powdered carbon material may be 1 nm or more, or 5 nm or more, from the viewpoint of ease of production. It may be 10 nm or more, and from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, it may be 1000 nm or less, 500 nm or less, or 100 nm or less. good.
• the average particle size (secondary particles) of the powdery carbon material may be 0.1 ⁇ m or more from the viewpoint of ease of production. It may be 1.0 ⁇ m or more, or 5.0 ⁇ m or more, and from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, it may be 200 ⁇ m or less, or 100 ⁇ m or less. , 50 ⁇ m or less, or 20 ⁇ m or less.
• the specific surface area of the powdered carbon material may be 657 m 2 /g or more, 1000 m 2 /g or more, or 1300 m 2 /g from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance. 1500 m 2 /g or more, or 1700 m 2 /g or more. From the viewpoint of ease of manufacture, it may be 2627 m 2 /g or less, 2500 m 2 /g or less, 2400 m 2 /g or less, or 2300 m 2 /g or less. good too.
• the specific surface area refers to the BET specific surface area and is a value measured by the BET multipoint method using nitrogen adsorption.
• the volume of the hole of the first shell and the volume of the hole of the second shell may be 1.0 cc/g or more. well, it may be 1.3 cc/g or more, it may be 1.6 cc/g or more, it may be 10.0 cc/g or less, or it may be 9.0 cc/g or less, It may be 8.0 cc/g or less. If the pore volume is 1.0 cc/g or more, a higher specific surface area can be obtained.
• the volume of the pores is a value determined from the amount of adsorption at a relative pressure (P/P0) of 0.96 by performing nitrogen adsorption isotherm measurement.
• the powdered carbon material of the present disclosure contains carbon as a main component.
• “having carbon as a main component” means that the content of carbon in the powdered carbon material is 50% by mass or more.
• the carbon content in the powdered carbon material may be 80% by mass or more, 95% by mass or more, or 98% by mass or more.
• the content (% by mass) of the powdery carbon material in the electromagnetic interference suppressing material is not particularly limited because it varies greatly depending on the application and the base material. From the viewpoint of further improving the electromagnetic wave absorption performance and the electromagnetic interference suppression performance, it may be 0.01 to 95% by mass with respect to the total amount of the electromagnetic interference suppression material.
• the content (% by mass) of the powdered carbon material in the electromagnetic interference suppression material is, from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, electromagnetic interference It may be 0.01 to 95% by mass, 0.01 to 20% by mass, or 0.05 to 10% by mass with respect to the total amount of the suppressing material.
• a molded body refers to a molded body that is manufactured by placing it in a mold such as a casting mold or a metal mold.
• the content (% by mass) of the powdered carbon material in the electromagnetic interference suppression material is, from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, electromagnetic interference It may be 0.05 to 20% by mass, 0.1 to 10% by mass, or 0.2 to 5% by mass with respect to the total amount of the suppressing material.
• the graphene of the present disclosure is a sheet material having a hexagonal lattice structure in which carbon atoms are bonded.
• Graphene may be in the state of a single layer having a layer thickness of one carbon atom, or may be in the state of multiple layers of two or more layers.
• Graphene may contain oxygen atoms, hydrogen atoms, nitrogen atoms, boron atoms, and the like in addition to carbon atoms.
• the content of graphene in the first shell-shaped body and the second shell-shaped body is not particularly limited, but from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, 90% It may be at least 95% by mass, or at least 98% by mass.
• the base material of the present disclosure contains at least one selected from organic substances and inorganic substances.
• the base material may contain only an organic substance, may contain only an inorganic substance, or may contain an organic substance and an inorganic substance.
• the organic matter contained in the base material is not particularly limited, and examples thereof include thermosetting resins and thermoplastic resins.
• thermosetting resins include epoxy resins, phenol resins, imide resins, and the like.
• thermoplastic resins include polyamide resins and polycarbonates.
• the organic substance may be a molded body from the viewpoint of reducing moisture permeability, and as another aspect, it may be a foam from the viewpoint of improving electromagnetic absorption capacity and reducing weight by increasing the surface area. good.
• foams examples include foamed polyurethane, foamed polystyrene, foamed polyvinyl chloride, foamed polyethylene, foamed polypropylene, and foamed polyethylene terephthalate.
• Polyurethane foam may be used from the viewpoint of improving the electromagnetic absorption capacity and reducing the weight by increasing the surface area.
• the organic substance may be a thermosetting resin from the viewpoint of the reliability of the molded article using the electromagnetic interference suppressing material, and from the viewpoint of electrical insulation and heat resistance of the molded article using the electromagnetic interference suppressing material. , an epoxy resin, or an imide resin.
• Polyurethane may be used from the viewpoint of ease of production, durability, weather resistance, etc.
• Polycarbonate-based polyurethane having good hydrolysis resistance may be used for outdoor use.
• One type of the organic matter may be used, or two or more types may be used in combination.
• the epoxy resin used as an organic substance has two or more epoxy groups in one molecule and is not particularly limited in molecular structure, molecular weight, etc., as long as it is commonly used in electronic parts.
• the epoxy resins include, for example, phenol novolac type epoxy resins, cresol novolak type epoxy resins, aliphatic epoxy resins such as dicyclopentadiene derivatives, and aromatic epoxy resins such as biphenyl type, biphenyl aralkyl type, naphthyl type and bisphenol type epoxy resins. etc. These epoxy resins may be used alone or in combination of two or more. There are no particular restrictions on the properties, and it may be liquid or solid at room temperature (25°C).
• the epoxy resin may be a solid cresol novolak type epoxy resin.
• the solid cresol novolac type epoxy resin can be obtained as a commercial product, and examples thereof include N670 (manufactured by DIC Corporation).
• the epoxy resin may be a liquid epoxy resin, and specific examples thereof include bisphenol A type epoxy resin and bisphenol F type epoxy resin.
• Liquid bisphenol A type epoxy resins are commercially available, and examples thereof include Epomic (registered trademark) R140 (manufactured by Mitsui Chemicals, Inc.).
• a liquid epoxy resin refers to an epoxy resin that exhibits a liquid state at 25°C.
• the epoxy equivalent of the epoxy resin may be 140 or more from the viewpoint of the thermomechanical properties of the molded product using the electromagnetic interference suppression material. From the viewpoint of electromagnetic wave absorption performance, it may be 200 or more.
• the upper limit of the epoxy equivalent may be 400 or less, or 380 or less, from the viewpoint of thermomechanical properties.
• the epoxy resin may be an epoxy resin having a polyoxyalkylene structure represented by (R 1 O)m and a polyoxyalkylene structure represented by (R 2 O)n.
• R 1 and R 2 each independently represent an alkylene group having 1 or more carbon atoms.
• m+n may be 1 or more and 50 or less, or 1 or more and 20 or less.
• m may be 0 or more and 49 or less, or may be 0 or more and 19 or less.
• n may be 1 or more and 50 or less, or 1 or more and 20 or less.
• the alkylene group represented by R 1 and R 2 includes, for example, an alkylene group having 1 to 6 carbon atoms, specifically a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a hexa A methylene group etc. are mentioned. From the viewpoint of electromagnetic wave absorption performance, the alkylene group may be a methylene group or an ethylene group.
• m R 1 O groups a plurality of R 1 may be the same alkylene group or alkylene groups having different carbon numbers.
• n R 2 O groups a plurality of R 2 may be the same alkylene group or alkylene groups with different carbon numbers.
• Examples of epoxy resins having a polyoxyalkylene structure include liquid epoxy resins having a bisphenol A skeleton, polyethylene glycol diglycidyl ether, and the like.
• Commercially available liquid epoxy resins having a bisphenol A skeleton include Licaresin BEO-60E (manufactured by Shin Nippon Rika Co., Ltd.) represented by the following general formula (1), and commercially available polyethylene glycol diglycidyl ethers. Examples thereof include Epolite 400E (manufactured by Kyoeisha Chemical Co., Ltd.) containing a compound represented by the following general formula (2) as a main component.
• examples of imide resins used as organic substances include bisallyl nadimide and the like.
• Bisallyl nadimide is commercially available, and examples thereof include BANI-M (manufactured by Maruzen Petrochemical Co., Ltd.) and BANI-X (manufactured by Maruzen Petrochemical Co., Ltd.).
• the polyurethane used as the organic substance is not particularly limited in terms of molecular structure, etc., as long as it is commonly used in electronic parts.
• Polyurethane foams are generally obtained by using polyols, polyisocyanates, and a foaming agent as essential components, adding a catalyst, a foaming aid, and the like, and reacting and foaming them.
• Polyol components include polyester polyols, polyether polyols, polycarbonate polyols, polymer polyols, and the like. These polyols may be used alone or in combination of two or more.
• polyester polyol include aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as adipic acid, suberic acid, sebacic acid and brassylic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and ethylene glycol and polyester polyols containing aliphatic diols having 1 to 6 carbon atoms such as diethylene glycol, ether glycols such as dipropylene glycol, and the like as polyol components (alcohol components).
• isocyanate component various known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used.
• tolylene diisocyanate TDI
• diphenylmethane diisocyanate MDI
• dicyclohexylmethane diisocyanate triphenyl diisocyanate
• xylene diisocyanate XDI
• polymethylene polyphenylene polyisocyanate hexamethylene diisocyanate
• IPDI isophorone diisocyanate
• orthotoluidine diisocyanate naphthyl Diisocyanate
• xylylene diisocyanate lysine diisocyanate and the like
• foaming agents include water, freon, pentane, and the like.
• the content (% by mass) of the organic matter in the electromagnetic interference suppression material is from the viewpoint of further improving the electromagnetic interference suppression performance and the electromagnetic interference suppression performance. It may be 1 to 40% by mass, 3 to 30% by mass, 4 to 25% by mass, or 5 to 20% by mass with respect to the total amount of the material.
• the content (% by mass) of the organic substance in the electromagnetic interference suppression material is, from the viewpoint of further improving electromagnetic wave absorption performance and electromagnetic interference suppression performance, electromagnetic interference It may be 80 to 99.95% by mass, 90 to 99.9% by mass, or 95 to 99.8% by mass with respect to the total amount of the suppressing material.
• the electromagnetic interference suppressing material of the present disclosure may further include a curing agent, a curing accelerator, and the like.
• a curing agent include aliphatic amines, aromatic amines, dicyandiamides, dihydrazide compounds, acid anhydrides, and phenol resins. These may be used alone or in combination of two or more.
• the curing accelerator examples include organic peroxides such as dicumyl peroxide and dibutyl peroxide; imidazole compounds such as 2-methylimidazole and 2-ethylimidazole; Organophosphorus compounds; diazabicycloalkene compounds such as 1,8-diazabicyclo[5,4,0]undecene-7 (DBU) and 1,5-diazabicyclo(4,3,0)nonene-5; 2-ethyl Tetraphenyl boron compounds such as -4-methylimidazole tetraphenyl borate, and the like. These may be used alone or in combination of two or more.
• organic peroxides such as dicumyl peroxide and dibutyl peroxide
• imidazole compounds such as 2-methylimidazole and 2-ethylimidazole
• Organophosphorus compounds diazabicycloalkene compounds such as 1,8-diazabicyclo[5,4,0]undecene-7 (D
• the content when the electromagnetic interference suppression material of the present disclosure contains a curing agent, the content is 0% by mass or more and 150.0% by mass or less with respect to 100% by mass of the thermosetting resin. It may be 0% by mass or more and 120% by mass or less, or 0% by mass or more and 100% by mass or less. In another aspect of the present disclosure, when the electromagnetic interference suppression material of the present disclosure contains a curing agent, the content is 1.0% by mass or more and 20.0% by mass or less with respect to the total amount of the electromagnetic interference suppression material. 2.0% by mass or more and 18.0% by mass or less, or 3.0% by mass or more and 15.0% by mass or less.
• the content may be 0.01% by mass or more and 10.0% by mass or less with respect to the total amount of the electromagnetic interference suppressing material. 05% by mass or more and 5.0% by mass or less, or 0.1% by mass or more and 3.0% by mass or less.
• the electromagnetic interference suppression material of the present disclosure may further contain a dispersing aid.
• the dispersing aid may be any material as long as it is a material for stably and highly dispersing the fine particles in the matrix resin.
• a ring agent is used.
• the dispersing aid include surfactants such as anionic surfactants such as carboxylates and cationic surfactants such as quaternary ammonium salts; coupling agents having amine-based functional groups and sulfide-based functional groups; A cellulose nanofiber etc. are mentioned.
• the cellulose nanofibers are bipolar ultrafine solids that improve the dispersibility of the filler by surface-active action.
• Cellulose nanofibers may already be highly dispersed in liquids such as water or thermosetting resin oligomers.
• the average fiber length of the cellulose nanofibers may be 1 ⁇ m or more and 100 ⁇ m or less, or 5 ⁇ m or more and 50 ⁇ m or less, from the viewpoint of workability and fluidity.
• the average fiber diameter of the cellulose nanofibers, including aggregates may be 1 nm or more and 1000 nm or less, or may be 4 nm or more and 500 nm or less.
• the average fiber length and average fiber diameter of cellulose nanofibers can be measured using a scanning electron microscope (SEM) in the same manner as the average fiber length and average fiber diameter of carbon nanotubes. .
• Examples of commercially available coupling agents having the amine-based functional group and the sulfide-based functional group include SUMILINK (registered trademark) 100 (manufactured by Sumitomo Chemical Co., Ltd.).
• Examples of commercially available cellulose nanofibers include ELLEX-S (manufactured by Daio Paper Co., Ltd.).
• the content is 0.1 to 30% by mass based on the total amount of the electromagnetic interference suppressing material from the viewpoint of dispersibility and thermomechanical property retention. , 0.2 to 10% by mass, or 0.3 to 5% by mass.
• the electromagnetic interference suppressing material of the present disclosure includes synthetic waxes, natural waxes, higher fatty acids, and higher fatty acids that are generally blended in this type of electromagnetic interference suppressing material within the scope of the present disclosure.
• release agents such as esters of fatty acids; colorants such as cobalt blue; modifiers such as silicone oil and silicone rubber; hydrotalcites; They can be blended as needed.
• Each of these additives may be used singly or in combination of two or more.
• the content of each of these additives in the electromagnetic interference suppression material of the present disclosure is 0.05 to 30.0% by mass as the total amount of each additive with respect to the total amount of the electromagnetic interference suppression material. may be 0.2 to 20.0% by mass.
• the inorganic substance contained in the base material is not particularly limited as long as it is an inorganic substance used in electronic parts, and examples thereof include the inorganic substance (A) and the inorganic substance (B) described below. These may be used alone or in combination of two or more.
• the inorganic substance (A) includes inorganic fillers such as silica, alumina, magnesium oxide, titanium oxide, barium titanate, silicon nitride, aluminum nitride, silicon carbide and tungsten carbide, amorphous magnetic metal alloys, Ni—Fe alloys, Pure iron, mild steel, silicon steel (Fe-Si alloys), Fe-Al alloys, Fe-Si-Al alloys, Co-Fe alloys, soft magnetic materials such as carbonyl iron, magnetism such as magnetite and ferrite It is at least one selected from the group consisting of inorganic substances other than the inorganic substance (B) described later.
• inorganic fillers such as silica, alumina, magnesium oxide, titanium oxide, barium titanate, silicon nitride, aluminum nitride, silicon carbide and tungsten carbide, amorphous magnetic metal alloys, Ni—Fe alloys, Pure iron, mild steel, silicon steel (Fe-Si alloys), Fe-
• the inorganic substance (A) may be used together with an organic substance.
• an organic substance from the viewpoint of reducing the expansion coefficient or increasing the thermal conductivity of the electromagnetic interference suppression material, at least one selected from silica and alumina may be used, or silica may be used.
• at least one selected from ferrite and amorphous magnetic metal alloys may be used.
• the shape of the inorganic substance (A) is not particularly limited, but examples thereof include powdery, spherical, flaky, fibrous and the like.
• the shape of the inorganic substance may be powdery or spherical.
• the average particle size of the inorganic substance (A) is not particularly limited, but may be 0.1 ⁇ m or more and 100 ⁇ m or less, may be 0.2 ⁇ m or more and 75 ⁇ m or less, or may be 0.2 ⁇ m or more and 50 ⁇ m or less. good too.
• the average particle size is the volume average particle size
• the average particle size of the inorganic substance (A) is the average length of the particles measured using a laser diffraction particle size distribution analyzer. It can be calculated as a value.
• the electromagnetic interference suppression material of the present disclosure contains the inorganic substance (A), from the viewpoint of further improving the electromagnetic wave absorption performance and the electromagnetic interference suppression performance, the content is 30 to 92 masses with respect to the total amount of the electromagnetic interference suppression material. %, 40 to 90% by mass, or 50 to 88% by mass.
• the electromagnetic interference suppressing material of the present disclosure When the electromagnetic interference suppressing material of the present disclosure is used as a semiconductor encapsulant, metal foreign matter is removed in the process of manufacturing the semiconductor encapsulant. When metal foreign matter is removed using a magnet, the magnetic material is regarded as foreign matter and removed, resulting in a poor yield.
• the electromagnetic interference suppression material of the present disclosure contains the magnetic substance, the content thereof may be 1% by mass or less with respect to the total amount of the electromagnetic interference suppression material, and may be 0.5% by mass or less. It may be less than or equal to 0% by mass.
• the content of the magnetic material may be equal to or less than the above value from the viewpoint of reducing the weight of the molded product to be obtained.
• Inorganic substance (B) Inorganic substance (B) are ceramics.
• the ceramics are not particularly limited, but specific examples include sintered bodies containing metal oxides, nitrides, carbides, etc. as main components.
• Specific examples of the metal oxide include alumina, zirconia, and magnesium oxide.
• Specific examples of the metal nitride include aluminum nitride, boron nitride, and silicon nitride.
• Specific examples of the metal carbide include silicon carbide and boron carbide.
• the ceramic may be at least one sintered body selected from alumina and aluminum nitride.
• the ceramics may be a molded body, or may be porous alumina or the like that is a foam.
• the powdered carbon material according to the present disclosure for example, uses particles of alumina, magnesium oxide, etc. as a template, coats a carbon layer on the template, prepares carbon-coated particles, and dissolves and removes the template. It can be manufactured by a method having a second step and a third step of heat treatment. By using such a method, it is possible to easily obtain a powdery carbon material having a high specific surface area and having an average number of graphene layers of 4 or less.
• ⁇ First step> (template)
• template As a template for synthesizing the powdery carbon material of the present embodiment, it is possible to introduce an organic substance on the surface and inside the pores, to keep the original structure stable during CVD processing, and to easily separate from the generated powdery carbon material. It is necessary to be able to For this reason, it may be one that has good heat resistance and can be removed using an acid or an alkali.
• the resulting powdered carbon-based material has pores that reflect the shape of the mold itself. In other words, the carbon material is synthesized with the morphology of the template transferred.
• the template may be a material having a uniform structure and composition with a uniform particle size, and by using such a material, it is possible to prepare a powdered carbon material having pores of a controlled size. can.
• a material capable of controlling the average number of layers of graphene to be obtained to be 4 or less may be used in order to obtain a high specific surface area.
• Such templates include particles of alumina, silica, magnesium oxide, tungsten carbide, aluminum nitride, cerium oxide, titanium oxide, calcium carbonate, and the like. These particles may be nanoparticles. From the viewpoint of the physical properties of the material that the mold should have and the physical properties of the resulting powdered carbon material, it may be at least one particle selected from alumina and magnesium oxide, may be alumina particles, or may be alumina nanoparticles. may Although the type of alumina is not particularly limited, ⁇ -alumina and ⁇ -alumina may be used.
• the average particle size of the particles used for the template is not particularly limited, but the average particle size may be 4 to 100 nm or 5 to 20 nm. When the average particle size is 4 nm or more, handling is easy and carbon coverage is good. In addition, since the gas permeability of the carbon source is improved when the carbon source is coated, uniform carbon coating is facilitated. On the other hand, if the average particle size is 100 nm or less, a powdery carbon material having a high specific surface area (BET specific surface area) can be obtained. In addition, it is possible to reduce the decrease in the yield of the powdered carbon material due to the relative increase in the amount of the template that is melted in the subsequent steps.
• BET specific surface area specific surface area
• the particles may be used by being mixed with a granular spacer.
• a spacer By using a spacer, it is possible to secure an appropriate gap between the particles, and to reduce the pressure loss caused by the particles being too densely packed.
• the spacer may be particles having an average particle size of, for example, 100 to 5000 ⁇ m.
• the material of the spacer is not particularly limited as long as it can be sieved after carbon coating, and it may be one that does not decompose at 900 to 1000°C. Alternatively, it may be one that can be dissolved and removed at the same time as the template. Examples include quartz sand, silica, alumina, silica-alumina, titania and the like. For example, when quartz sand is used, it may be washed with an acid in advance, calcined at 600 to 1000° C. for 1 to 5 hours, and controlled to have the above particle size.
• the compounding ratio of the particles and spacers is not particularly limited, but for example, the mass ratio of (particles:spacers) may be from 0.1:10 to 10:10, or from 1:10 to 10:10. There may be. Within the above range, the powdery carbon material can be obtained with a high yield.
• the method of coating the carbon layer on the surface of the template particle is not particularly limited, and either a wet method or a dry method can be applied. Vapor Deposition (CVD) may also be used.
• CVD Vapor Deposition
• the CVD method which is used to introduce an organic compound and deposit a carbon layer on a template, is an industrial technique for making a thin film of a specific element or elemental composition (for example, a thin film of carbon) on a substrate such as a template.
• a gas containing a raw material is given energy by heat or light, or is turned into plasma with a high frequency, the raw material is radicalized by a chemical reaction or thermal decomposition and becomes highly reactive, and the raw material is deposited on the substrate. It is a technology that utilizes adsorption and deposition.
• the organic compound used in the CVD method may be a gas at room temperature, or may be vaporizable. Vaporization methods include a method of heating to a boiling point or higher, a method of reducing the pressure of the atmosphere, and the like.
• the organic compound to be used can be appropriately selected from carbon source substances and used. In particular, it may be a compound that thermally decomposes when heated, or a compound that can deposit a carbon layer on the surface of the particles used as the template.
• the organic compound to be used may be an organic compound containing hydrogen.
• the organic compound may be an organic compound containing unsaturated or saturated hydrocarbons, or a mixture thereof.
• the organic compound to be used may be an unsaturated linear or branched hydrocarbon having a double bond and/or a triple bond, a saturated linear or branched hydrocarbon, or the like, and a saturated cyclic hydrocarbon. , benzene, toluene, and other aromatic hydrocarbons.
• alcohols such as methanol and ethanol, or nitrogen-containing compounds such as acetonitrile and acrylonitrile may be used.
• organic compounds examples include acetylene, methylacetylene, ethylene, propylene, isoprene, cyclopropane, methane, ethane, propane, benzene, toluene, vinyl compounds, ethylene oxide, methanol, ethanol, acetonitrile, acrylonitrile and the like.
• An organic compound may be used individually by 1 type, and may be used in combination of 2 or more types. Among them, organic compounds that can enter the voids between particles, such as acetylene, ethylene, propylene, methane, and ethane, may be used. From the viewpoint of depositing highly crystalline carbon, methane, propylene, and benzene may be used.
• Methane may also be used from the viewpoint of obtaining carbon with high thermal decomposition temperature and high crystallinity.
• the organic compounds used for CVD at higher temperatures and those used for CVD at lower temperatures may be the same or different.
• acetylene, ethylene, etc. may be used for low-temperature CVD
• propylene, isoprene, benzene, etc. may be used for high-temperature CVD.
• the particles When the organic compound is introduced onto the particles, the particles may be evacuated in advance, or the system itself may be evacuated. Any method that deposits carbon by CVD may be used. For example, carbon produced by chemical reaction or thermal decomposition of an organic compound may be deposited (or adsorbed) on alumina particles to coat the alumina particles with a carbon layer.
• the pressure during the CVD process is not particularly limited, and may be, for example, 1 kPa to 200 kPa, or 50 to 150 kPa.
• the heating temperature for the CVD treatment may be any condition that allows the formation of several carbon layers or less on the particles, and an appropriate temperature can be selected depending on the organic compound used.
• the heating temperature may be 400 to 1500°C, 450 to 1100°C, or 550 to 950°C.
• the temperature when propylene is used as the organic compound, the temperature may be 700 to 900°C, and when methane is used, the temperature may be 900 to 1100°C.
• the temperature may be about 50 to 200° C. lower than the decomposition temperature of the organic compound.
• the particles are heated to a temperature higher than the decomposition temperature of the organic compound, vapor phase carbon deposition becomes significant. By doing so, for example, unevenness in the amount of carbon deposited on the surface and inside of the particles can be reduced, and uniform deposition can be achieved. .
• the heating temperature can be appropriately selected according to the CVD processing time and/or the pressure in the reaction system.
• the product may be analyzed and the temperature required to achieve the desired number of layers may be set based on the results.
• the rate of temperature increase during the CVD process is not particularly limited, but may be 1 to 50° C./min, or may be 5 to 20° C./min.
• the processing time in the CVD processing (CVD processing time at a predetermined heating temperature) may be any time required to obtain graphene having an average number of layers of 4 or less, and an appropriate time can be selected depending on the organic compound or temperature used.
• the processing time in CVD processing may be 5 minutes to 8 hours, 0.5 to 6 hours, or 1 to 5 hours.
• the product may be analyzed and the time required for sufficient carbon deposition may be set based on the results.
• the CVD treatment may be performed under reduced pressure, vacuum, or pressure, or in an inert gas atmosphere.
• examples of the inert gas include nitrogen, helium, neon, argon, etc. Nitrogen may be used.
• carbon can be easily deposited or adsorbed on the particles in the gas phase by heating the gaseous organic compound together with a carrier gas while circulating it so as to contact the particles.
• the type of carrier gas, flow rate, flow rate and heating temperature are appropriately adjusted depending on the type of organic compound used.
• the carrier gas includes, for example, the above inert gases, and may be nitrogen, or a mixture with oxygen gas or hydrogen gas.
• the flow rate of the carrier gas may be, for example, 0.05 to 1.0 m/min, or may be 0.32 to 0.64 m/min.
• the amount of the organic compound introduced may be 1 to 30% by volume or 5 to 20% by volume with respect to the total amount of the carrier gas and the organic compound.
• an organic compound may be introduced by a wet method such as an impregnation method and carbonized. Also, before introducing the organic compound and performing the CVD, the material may be impregnated with the organic compound and carbonized.
• a thermopolymerizable monomer such as furfuryl alcohol having a high carbonization yield can be used.
• the method for impregnating the organic compound with the organic compound if the organic compound is liquid, it is used as it is, or if it is solid, it is mixed with a solvent, and if it is solid, it is dissolved in the solvent and brought into contact with the particles.
• the carbon-coated particles may be heat-treated to carbonize the carbon layer and deposit highly crystalline carbon on the surface of the particles.
• the obtained powdered carbon material has higher crystallinity and a higher specific surface area.
• the heat treatment may be performed during CVD processing, or by other methods.
• the heat treatment method is not particularly limited, and heat treatment may be performed using a high-frequency induction heating furnace or the like.
• the step of dissolving and removing the template which is the second step of the present embodiment, is a step of dissolving and removing the template from the carbon-coated particles to obtain a shell-like body.
• Alkaline solutions such as NaOH, KOH, LiOH, RbOH and CsOH may be used for dissolving and removing the template.
• the alkaline solution may have a concentration of 1 to 5M, for example.
• the alkaline solution may be 30 times or more, or 50 times or more, the stoichiometric ratio of the particles. If the ratio is 30 times or more of the stoichiometric ratio, it is possible to suppress the remaining of the template particles.
• carbon-coated particles When dissolving and removing, for example, carbon-coated particles may be placed in the alkaline solution and heat treated at a heat treatment temperature of 200 to 300°C. At this time, the sample of the carbon-coated particles may be pulverized in advance in order to bring the alkaline solution into uniform contact with the sample.
• the rate of temperature increase during heat treatment is not particularly limited, and is, for example, 200 to 300° C./hour.
• the heat treatment time (holding time at a predetermined heat treatment temperature) is not particularly limited, and is, for example, 1 to 5 hours. This dissolution removal step may be performed multiple times.
• the product can be analyzed and the conditions required for sufficient template removal can be set based on the results.
• the shell-like body may be collected by filtration or dried by vacuum heating drying.
• the vacuum heat drying conditions are not particularly limited, and for example, the vacuum heat drying temperature can be 100 to 200°C. Also, the vacuum heat drying time can be set to, for example, 1 to 10 hours.
• the third step is a heat treatment step. After the second step, through the third step, the crystallinity of the coated carbon is enhanced and stabilized. Therefore, the powdered carbon material has a higher level of electrical conductivity, corrosion resistance, and high specific surface area.
• the heat treatment temperature is not particularly limited, but may be 1100 to 1850°C or 1550 to 1830°C. If the heat treatment temperature is 1550° C. or higher, the effects of the present invention can be obtained more remarkably. Moreover, if the temperature is 1850° C. or lower, it is possible to prevent the remaining template from reacting with carbon.
• the heat treatment time (holding time at a predetermined heat treatment temperature) may be 0.1 to 10 hours, 0.2 to 5 hours, or 0.5 to 2 hours. In addition, you may perform a heat processing process under reduced pressure. Graphene having an average number of layers of 4 or less can be obtained by the method including the first to third steps.
• the electromagnetic interference suppressing material is a base material containing at least one organic material, and a powdered carbon material, if necessary.
• the other components may be sufficiently uniformly mixed with a mixer or the like, and then kneaded with a disperser, a kneader, a three-roll mill, a twin-screw heating roll, a twin-screw heating extrusion kneader, or the like.
• the kneading treatment may be performed by heating.
• the temperature at that time may be 70° C. or higher and 150° C. or lower, or may be 75° C. or higher and 120° C. or lower.
• the electromagnetic interference suppression material of the present disclosure is, for example, cooled and solidified after the kneading treatment, and pulverized to an appropriate size by a cutting mill, ball mill, cyclone mill, hammer mill, vibration mill, cutter mill, grinder mill, speed mill, etc. may be used as
• the mixture obtained after the kneading treatment may be pressed into a sheet by a molding machine under the conditions of a temperature of 50° C. or higher and 100° C. or lower and a pressure of 0.5 MPa or higher and 1.5 MPa or lower.
• the electromagnetic interference suppression material of the present disclosure can be used as a radio wave absorber, a noise suppression sheet, a semiconductor sealing material, a sealing sheet, a wire coating material, and the like.
• a resin-encapsulated electronic component is obtained by encapsulating a semiconductor element fixed on a substrate with a semiconductor element encapsulant containing the electromagnetic interference suppressing material of the present disclosure. be able to.
• a known molding method is used without particular limitation. The most common molding method is low-pressure transfer molding, but molding by injection molding, cast molding, compression molding, etc. is also possible.
• a heat treatment is performed in the mold by a transfer molding machine at a temperature of 150° C. to 200° C. for a time of 20 seconds to 200 seconds, and the molded product is removed from the mold to complete curing.
• Heat treatment may be performed at a temperature of 150° C. to 200° C. for 2 hours to 12 hours.
• the compression molding method first, a substrate on which a semiconductor element is mounted is supplied to the upper mold of the mold, and the electromagnetic interference suppressing material of the present disclosure is supplied into the cavity of the lower mold. Next, by clamping both the upper and lower molds with a required mold clamping pressure, the substrate with the semiconductor element mounted thereon is immersed in the electromagnetic interference suppressing material heated and melted in the cavity of the lower mold. After that, the electromagnetic interference suppressing material heated and melted in the lower mold cavity is pressed by the cavity bottom member, a required pressure is applied under reduced pressure, and compression molding is performed.
• the molding conditions may be a temperature of 120° C. or higher and 200° C. or lower and a pressure of 2 MPa or higher and 20 MPa or lower.
• the electromagnetic interference material is obtained by the following method.
• An appropriate organic binder, solvent, etc. are added to and mixed with ceramic raw material powder to form a slurry.
• a ceramic green sheet is produced by molding this slurry into a sheet by employing a conventionally well-known doctor blade method or the like. It is obtained by firing this ceramic green sheet. It may be obtained by dispersing the powdered carbon material in a solvent and immersing the obtained ceramics in a mixed dispersion liquid containing other components as necessary. Alternatively, the ceramic green sheet may be obtained by sintering the powdered carbon material with the component that can be the ceramic green sheet.
• the components that can be used as ceramics and the conditions for firing the powdered carbon material may be adjusted as appropriate according to the components that can be used as ceramics. It may be carried out in an inert gas atmosphere.
• the firing temperature may be 600°C to 1800°C or 1000°C to 1600°C.
• an electromagnetic interference suppression material containing foam as an organic or inorganic substance is obtained by dispersing a powdered carbon material in a solvent and immersing the foam in a mixed dispersion containing other components as necessary.
• a foamable component, a powdered carbon material, and other components blended as necessary may be foamed using a foaming machine, or may be molded by a pressure press and then fired in the atmosphere to foam. You may obtain by these methods, such as a method.
• the conditions for foaming these are not particularly limited, and may be appropriately adjusted according to the components that can be foamed.
• the alumina nanoparticles were heated from room temperature to 900°C at a heating rate of 10°C/min under the condition that the flow rate of N2 gas was adjusted to 224ml/min, and held at 900°C for 30 minutes.
• N2 gas as a carrier gas
• 20% by volume of methane with respect to the total amount of carrier gas and methane was introduced into the reaction tube, and chemical vapor deposition (CVD) treatment was performed at 900 ° C for 2 hours. gone.
• the methane gas flow rate was adjusted to 45 ml/min, and the N 2 gas flow rate was adjusted to 179 ml/min.
• Carbon-coated alumina nanoparticles and 5M NaOH (50 times or more the stoichiometric ratio) are placed in a Teflon (registered trademark) autoclave container, and heated at a temperature increase rate of 250 ° C./hour using a muffle furnace, It was held at 250° C. for 2 hours. Then, after cooling naturally, it was collected by filtration and dried by vacuum heat drying at 150° C. for 6 hours to obtain a shell-like body.
• the heat treatment conditions were as follows: First, the temperature was raised from room temperature to 1000°C at 16.7°C/min over 60 minutes, then the temperature was raised at 5°C/min to 1800°C over 160 minutes, and then the temperature was increased to 1800°C for 60 minutes. It was heated for 1 minute and then naturally cooled to room temperature to obtain a powdered carbon material 1 (second shell-like body).
• ⁇ Production Example 2> (Production of carbon-coated alumina nanoparticles) Alumina nanoparticles (TM300 manufactured by Taimei Chemical Industry Co., Ltd., crystal phase: ⁇ -alumina, average particle diameter: 7 nm, specific surface area: 220 m 2 /g) and quartz sand (manufactured by Sendai Wako Pure Chemical Industries, Ltd.) as a spacer , at a mass ratio of 3:20 (alumina nanoparticles:quartz sand). At this time, the quartz sand used was immersed in 1M hydrochloric acid for 12 hours, heated in air at 800° C. for 2 hours in a muffle furnace, and sieved at intervals of 180 ⁇ m. A mixture of alumina nanoparticles and quartz sand prepared above was placed in a reaction tube (inner diameter: 37 mm), and CVD using methane as a carbon source (methane CVD) was performed.
• the alumina nanoparticles were heated from room temperature to 900°C at a heating rate of 10°C/min under the condition that the flow rate of N2 gas was adjusted to 224ml/min, and held at 900°C for 30 minutes.
• N2 gas as a carrier gas
• 20% by volume of methane with respect to the total amount of carrier gas and methane was introduced into the reaction tube, and chemical vapor deposition (CVD) treatment was performed at 900 ° C for 6 hours. gone.
• the methane gas flow rate was adjusted to 45 ml/min, and the N 2 gas flow rate was adjusted to 179 ml/min.
• Powdered carbon material 2 (second shell-like body) was obtained by the same operation as manufacturing method 1.
• ⁇ Comparative Production Example 1> (Production of carbon-coated alumina nanoparticles) Alumina nanoparticles (TM300 manufactured by Taimei Chemical Industry Co., Ltd., crystal phase: ⁇ -alumina, average particle diameter: 7 nm, specific surface area: 220 m 2 /g) and quartz sand (manufactured by Sendai Wako Pure Chemical Industries, Ltd.) as a spacer , at a mass ratio of 3:20 (alumina nanoparticles:quartz sand). At this time, the quartz sand used was immersed in 1M hydrochloric acid for 12 hours, heated in air at 800° C. for 2 hours in a muffle furnace, and sieved at intervals of 180 ⁇ m. A mixture of alumina nanoparticles and quartz sand prepared above was placed in a reaction tube (inner diameter: 37 mm), and CVD using methane as a carbon source (methane CVD) was performed.
• the alumina nanoparticles were heated from room temperature to 950°C at a heating rate of 10°C/min under the condition that the flow rate of N2 gas was adjusted to 224 ml/min, and held at 950°C for 30 minutes.
• N2 gas as a carrier gas
• 20% by volume of methane with respect to the total amount of carrier gas and methane was introduced into the reaction tube, and chemical vapor deposition (CVD) treatment was performed at 950 ° C. for 20 hours. gone.
• the methane gas flow rate was adjusted to 45 ml/min, and the N 2 gas flow rate was adjusted to 179 ml/min.
• a powdery carbon material 3 (second shell-like body) was obtained by performing the same operation as in manufacturing method 1.
• Average number of graphene layers 2627 (m 2 /g)/specific surface area (m 2 /g)
• the powdered carbon materials 1 to 3 shown in Tables 2 and 3 used for the production of the electromagnetic interference suppressing material are the powdered carbon materials obtained in Production Examples 1 and 2 and Comparative Production Example 1, respectively.
• the powdered carbon materials 1 to 3 were pulverized products of 1 to 3, and the powdered carbon materials 1 to 3 were pulverized and classified, respectively, and prepared to have an average particle size of 10 ⁇ m.
• Examples 1 to 3 and Comparative Examples 1 to 5 Each component of the type and compounding amount shown in Table 2 was put into a Henschel mixer, mixed, then put into a twin-screw roll kneading device heated to 110° C., and heated and kneaded until uniform. Next, the resulting hot kneaded material was put into a cold roll, stretched into a sheet, and then pulverized to obtain an electromagnetic interference suppressing material composition. The resulting electromagnetic interference suppressing material composition was compression molded into a compact having a thickness of 0.5 mm, 1.0 mm or 25 mm (temperature: 175°C, pressure: 10 MPa) to obtain an electromagnetic interference suppressing material.
• Example 4 Adipic acid, diethylene glycol, and trimethylolpropane were placed in a flask, mixed by heating at 120° C., triisopropyl titanate was added, and the mixture was dehydrated under reduced pressure at 240° C. to prepare an adipic acid-based polyester polyol.
• the obtained polyol mixture and the isocyanate "Sumidur 44V20" (manufactured by Sumika Bayer Urethane Co., Ltd.) were prepared and mixed and stirred so that the urethane index was 105. to obtain a rigid polyurethane foam (polyurethane foam).
• a rigid polyurethane foam having a size of 440 mm x 440 mm x 25 mm was obtained by the same operation and cut into 440 mm x 440 mm x 0.5 mm or 440 mm x 440 mm x 1.0 mm.
• a mixed dispersion 1 was prepared by mixing 1 part by mass of the powdered carbon material 1 obtained in Production Example 1 with 10000 mL of a urethane-based emulsion "Superflex" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and mixed and dispersed.
• the polyurethane foam obtained in Liquid 1 was immersed at room temperature for 30 minutes, then heated at 120° C. for 120 minutes and dried to obtain an electromagnetic interference suppressing material in which the powdered carbon material was localized on the surface of the polyurethane foam.
• Example 5 and Comparative Examples 6 to 8> instead of using powdered carbon material 1 in Example 4, powdered carbon material 2 was used in Example 5, powdered carbon material 3 was used in Comparative Example 6, and carbon black (CB) was used in Comparative Example 7. was used, and in Comparative Example 8, an electromagnetic interference suppressing material in which the carbon material was localized on the surface of the foamed polyurethane was obtained by the same operation except that carbon nanotubes (CNT) were used.
• CNT carbon nanotubes
• Example 6 50 parts by mass of the polyol mixture produced in Example 4, 50 parts by mass of the isocyanate "Sumidur 44V20" (manufactured by Sumika Bayer Urethane Co., Ltd.), and 1 part by mass of the powdered carbon material 1 obtained in Production Example 1.
• Example 4 An electromagnetic interference suppressing material was obtained, which was a polyurethane foam containing a powdered carbon material measuring 440 mm x 1.0 mm or 440 mm x 440 mm x 25 mm.
• Example 7 In Example 4, instead of using foamed polyurethane, ceramic sintered porous body "FA120" (manufactured by Fuji Chemical Co., Ltd., alumina, average pore diameter 100 ⁇ m, average porosity 45-50%) was used. An electromagnetic interference suppressing material was obtained in which the powdered carbon material was localized on the surface of the ceramic sintered porous body (foam) by the same operation except for the above.
• ⁇ Content of powdered carbon material (% by mass)>
• the content of the powdered carbon material is, when the "existence area of the carbon material" is "whole” (Examples 1 to 3, Example 6, Comparative Examples 1 to 5, Comparative Examples 9 to 11), from the mixing ratio, In the case of "surface” (Example 4, Example 5, Example 7, Comparative Examples 6 to 8, Comparative Example 12), it was determined from the mass increase before and after introduction of the carbon material to the surface.
• volume resistance at 150° C. was measured according to JIS K-6911:2006 using the electromagnetic interference suppression material molded to a thickness of 1.0 mm.
• Electromagnetic wave absorption performance (frequency 10 GHz, near-field measurement system)> An electromagnetic interference suppressing material molded to a thickness of 0.5 mm is placed between a high-frequency oscillation device and a receiving antenna, and an electromagnetic wave intensity when an electromagnetic wave having a frequency of 10 GHz is generated is measured with and without the molded body.
• the ratio (the electromagnetic wave intensity when the electromagnetic interference suppressing material absorbs the electromagnetic wave/the electromagnetic wave intensity when the electromagnetic interference suppressing material is absent) was defined as the electromagnetic wave absorption performance in dB.
• the electromagnetic wave intensity was measured according to "The Institute of Electronics, Information and Communication Engineers Journal B Vol.J97-B No.3 pp.279-285".
• Electromagnetic wave absorption performance (frequency 5 GHz, far field measurement system)> A 1 mm thick copper plate (600 mm x 600 mm) was placed on the antireflection radio wave absorber, and an electromagnetic interference suppression material (440 mm x 440 mm) molded to a thickness of 25 mm was placed on the metal plate. Next, an antenna is attached to the network analyzer via a cable, an electromagnetic wave with a frequency of 5 GHz is transmitted from one antenna, reflected by the electromagnetic interference suppressing material and a metal plate placed therebelow, and received by the other antenna. The electromagnetic wave intensity was measured by Further, without placing the electromagnetic interference suppressing material on the metal plate, the electromagnetic wave intensity was measured by radiating electromagnetic waves in the same manner as described above.
• the ratio of these was defined as the electromagnetic wave absorption performance in dB.
• the electromagnetic wave intensity was measured according to "Kagoshima Prefectural Industrial Technology Center Research Report No. 15 (2001), pp. 53-61".
• the electromagnetic interference suppressing materials of Examples 1 to 3 have good radio wave absorption performance. Moreover, since it has a high volume resistance, it can be said that the electromagnetic interference suppressing performance in the near field is also good. Further, as shown in Table 3, the electromagnetic interference suppressing materials of Examples 4 to 7 have good radio wave absorption performance.

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