JP2011144213A - Epoxy resin composition for carbon fiber-reinforced composite material, prepreg and carbon fiber-reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg providing both of excellent impact resistance and electroconductivity, and to provide a carbon fiber-reinforced composite material. <P>SOLUTION: The epoxy resin composition for the carbon fiber-reinforced composite material contains at least (A) an epoxy resin, (B) a curing agent and (C) thermoplastic resin particles containing an electroconductive material. The prepreg and the carbon fiber-reinforced composite material are obtained by using the resin composition. The carbon fiber-reinforced composite material comprises: a cured product of the epoxy resin composition for the carbon fiber-reinforced material, containing at least (A) the epoxy resin, (B) the curing agent and (C) the thermoplastic resin particles containing the electroconductive material; and carbon fibers. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an epoxy resin composition for a carbon fiber reinforced composite material having excellent mechanical properties and conductivity, a prepreg, and a carbon fiber reinforced composite material.

  Carbon fiber reinforced composite materials are useful because they are excellent in strength, rigidity, electrical conductivity, etc., and are useful for computers such as aircraft structural members, windmill blades, automobile skins, and IC trays and notebook computer housings (housings). Widely used in applications, the demand is increasing year by year.

  The carbon fiber reinforced composite material has, as one aspect thereof, a non-uniform material formed by molding a prepreg having carbon fibers that are reinforcing fibers and a matrix resin as essential constituent elements. There will be a large difference in physical properties in other directions. For example, the impact resistance shown by the resistance to falling weight impact is governed by the delamination strength determined by the plate edge delamination strength between the layers of the carbon fiber reinforced composite material, so it only improves the strength of the reinforcing fibers. Then, it is known that it does not lead to drastic improvement. In particular, a carbon fiber reinforced composite material using a thermosetting resin as a matrix resin reflects the low toughness of the matrix resin, and has a property of being easily broken by stress from other than the direction in which the reinforcing fibers are arranged. Therefore, various techniques have been proposed for the purpose of improving the physical properties of the carbon fiber reinforced composite material that can cope with stresses from other than the direction in which the reinforcing fibers are arranged.

  As one of them, a prepreg in which resin fine particles are dispersed in a surface portion has been proposed. For example, a technique for providing a high-toughness composite material with good heat resistance using a prepreg in which resin fine particles made of a thermoplastic resin such as nylon are dispersed on a partial surface has been proposed (see Patent Document 1). In addition, a technique has been proposed in which a high degree of toughness is expressed in a carbon fiber reinforced composite material by combining a matrix resin whose toughness has been improved by adding a polysulfone oligomer and resin fine particles made of a thermosetting resin (Patent Document 2). reference).

  However, these technologies give a resin layer that becomes an insulating layer between layers while providing high impact resistance. Therefore, among the conductivity that is one of the characteristics of the carbon fiber reinforced composite material, there is a disadvantage that the conductivity in the thickness direction is extremely inferior, and the carbon fiber reinforced composite material has both excellent impact resistance and conductivity. It was difficult.

  Therefore, as a method for improving the conductivity between layers, a method in which conductive particles such as metal particles and carbon particles (see Patent Document 3) are mixed in advance with a matrix resin, or a conductive film in a matrix resin (see Patent Document 4). ) Can be considered, but these methods are not sufficient to satisfy both high conductivity and impact resistance, and it is necessary to use particles and films corresponding to the thickness between layers. Inter-layer design was difficult.

  In addition, as a method for improving the adhesion between the matrix resin and the conductive particles, there is a method using a silane coupling agent (see Patent Document 5). This method is also sufficient to achieve both high conductivity and impact resistance. It was not satisfactory.

US Pat. No. 5,028,478 JP-A-3-26750 JP 2008-231395 A JP 2009-062473 A JP 2009-077405 A

  Accordingly, an object of the present invention is to provide an epoxy resin composition for carbon fiber reinforced composite materials having excellent mechanical properties and electrical conductivity, a prepreg, and a carbon fiber reinforced composite having electrical properties and electrical properties such as excellent impact resistance. The purpose is to provide materials.

  In order to achieve the above object, the present invention has any one of the following configurations.

  That is, the epoxy resin composition for carbon fiber reinforced composite material of the present invention comprises thermoplastic resin particles (hereinafter referred to as “conductive”) containing at least (A) an epoxy resin, (B) a curing agent, and (C) a conductive substance. It may be referred to as “substance-containing thermoplastic resin particles”.).

  According to a preferred embodiment of the epoxy resin composition for carbon fiber reinforced composite material of the present invention, (C) carbon containing 0.01 to 50% by mass of conductive material-containing thermoplastic resin particles in the epoxy resin composition. It is an epoxy resin composition for fiber-reinforced composite materials.

  According to a preferred aspect of the epoxy resin composition for a carbon fiber reinforced composite material of the present invention, the conductive resin is an epoxy resin composition for a carbon fiber reinforced composite material, which is carbon black.

  According to a preferred aspect of the epoxy resin composition for a carbon fiber reinforced composite material of the present invention, the conductive material is carbon fiber containing 10 to 80% by mass of the conductive material-containing thermoplastic resin particles (C). It is an epoxy resin composition for reinforced composite materials.

  According to a preferred aspect of the epoxy resin composition for carbon fiber reinforced composite material of the present invention, it is an epoxy resin composition for carbon fiber reinforced composite material, which is a thermoplastic resin having a glass transition temperature of 180 ° C. or lower. .

  According to a preferred embodiment of the epoxy resin composition for carbon fiber reinforced composite material of the present invention, (C) the epoxy resin composition for carbon fiber reinforced composite material having an average particle size of the conductive material-containing thermoplastic resin particles of less than 150 μm. is there.

  In addition, the prepreg of the present invention comprises carbon fiber reinforced epoxy resin composition for carbon fiber reinforced composite material containing at least (A) epoxy resin, (B) curing agent, and (C) conductive substance-containing thermoplastic resin particles. A prepreg impregnated.

  Moreover, the carbon fiber reinforced composite material of the present invention comprises an epoxy resin composition for a carbon fiber reinforced composite material containing at least (A) an epoxy resin, (B) a curing agent, and (C) a conductive substance-containing thermoplastic resin particle. , A carbon fiber reinforced composite material obtained by curing a prepreg impregnated in carbon fiber, or carbon containing at least (A) an epoxy resin, (B) a curing agent, and (C) a conductive substance-containing thermoplastic resin particle A carbon fiber reinforced composite material comprising a cured product of an epoxy resin composition for a fiber reinforced composite material and carbon fibers.

  In the present invention, a carbon fiber reinforced composite material obtained by curing a thermoplastic resin containing a conductive substance in an epoxy resin composition that is a matrix resin has excellent impact resistance and conductivity. Can be made. That is, in the prior art, if the impact resistance is high, the conductivity is low, and if the conductivity is high, only a carbon fiber reinforced composite material that is inferior in impact resistance can be obtained. And a carbon fiber reinforced composite material having both conductivity and conductivity.

  In addition, since the carbon fiber reinforced composite material of the present invention has both excellent impact resistance and conductivity, in addition to aircraft components, sports equipment such as tennis rackets and golf shafts, automobile bumpers and doors, etc. It can be preferably applied to an outer plate member and a structural member of an automobile such as a chassis and a front side member.

  As a result of pursuing the conductive mechanism of a carbon fiber reinforced composite material composed of carbon fiber, epoxy resin, curing agent and conductive substance-containing thermoplastic resin particles, the present inventors have formulated carbon containing a conductive substance-containing thermoplastic resin. It has been clarified that the epoxy resin composition for fiber reinforced composite material can obtain a carbon fiber reinforced composite material having excellent impact resistance and conductivity at a high level, and the present invention has been achieved.

  The epoxy resin composition for carbon fiber reinforced composite material, prepreg and carbon fiber reinforced composite material of the present invention each include (A) an epoxy resin, (B) a curing agent, and (C) a conductive substance-containing thermoplastic resin particle. In addition, the prepreg and the carbon fiber reinforced composite material further contain carbon fibers.

  The carbon fiber used in the present invention can be any type of carbon fiber depending on the application, but it is a carbon fiber having a tensile modulus of at least 280 GPa because it exhibits higher conductivity. Is preferred. Moreover, it is preferable that it is a carbon fiber which has a tensile elasticity modulus of 440 GPa at the maximum from the point of coexistence with impact resistance. In addition, from the viewpoint of impact resistance, a carbon fiber reinforced composite material having excellent impact resistance and high rigidity and mechanical strength is obtained, so that the tensile strength is preferably 4.4 to 6.5 GPa, The tensile elongation is also an important factor, and is preferably a high-strength, high-strength carbon fiber of 1.7 to 2.3%. Therefore, from the point of achieving both high conductivity and impact resistance, the tensile elastic modulus is at least 280 GPa, the tensile strength is at least 4.4 GPa, and the tensile elongation is at least 1.7%. Carbon fiber is most suitable. The tensile modulus, tensile strength and tensile elongation can be measured by a strand tensile test described in JIS R7601-1986.

  The carbon fiber used in the present invention can be produced as follows. First, in the case of an acrylic carbon fiber, a precursor made of a polyacrylonitrile copolymer having a constitution in which acrylonitrile is 90% by mass or more and a monomer copolymerizable with acrylonitrile is less than 10% by mass as a carbon fiber precursor. It is preferable to use fiber bundles. Examples of the copolymerizable monomer include acrylic acid, methacrylic acid, itaconic acid or their methyl ester, propyl ester, butyl ester, alkali metal salt, ammonium salt, allyl sulfonic acid, methallyl sulfonic acid, and styrene. At least one selected from the group consisting of sulfonic acids and alkali metal salts thereof can be used.

  The polyacrylonitrile-based precursor fiber bundle preferably has a single fiber fineness of 1.0 to 2.0 dtex, more preferably 1.1 to 1.7 dtex, and still more preferably 1.2 to 1.5 dtex. It is. If the single fiber fineness is less than 1.0 dtex, the elastic modulus and strength of the carbon fiber bundle are too high, and the productivity tends to be inferior. Moreover, when the single fiber fineness exceeds 2.0 dtex, it becomes easy to produce spots in the carbonization step, which may reduce the overall strength. The polyacrylonitrile-based precursor fiber bundle is heated and flame-resistant in an oxidizing atmosphere such as air, preferably in a temperature range of 200 ° C. to 300 ° C., to produce flame-resistant fibers.

  Next, before the carbonization treatment of the next step, the flameproof fiber is preliminarily carbonized in an inert atmosphere such as nitrogen, preferably within a temperature range of 300 ° C to 1000 ° C. Thus, after pre-carbonizing the flameproofed fiber, the maximum temperature is preferably 1000 to 1400 ° C, more preferably 1000 to 1300 ° C, and even more preferably 1100 to 1250 ° C in an inert atmosphere such as nitrogen. A carbon fiber bundle can be manufactured by carbonizing in the temperature range of. When the maximum carbonization temperature exceeds 1400 ° C., the elastic modulus of the carbon fiber bundle becomes too high, and when it is less than 1000 ° C., the crystal size of the carbon fiber becomes small and the growth of the carbon crystals is insufficient. When the fiber bundle has a high moisture content and the fiber-reinforced composite material is molded, the matrix resin may not be sufficiently cured, and the tensile strength of the fiber-reinforced composite material may not be sufficiently developed.

  Examples of commercially available carbon fibers include “Torayca (registered trademark)” T800SC-24K-10E and “Torayca (registered trademark)” T700SC-24K-50C (all of which are manufactured by Toray Industries, Inc.).

  The form and arrangement of the carbon fibers can be selected as appropriate from long fibers aligned in one direction, tows, woven fabrics, nonwoven fabrics, mats, knits, braids, rovings, choppeds, etc., but they are lighter and more durable In order to obtain a carbon fiber reinforced composite material, the carbon fibers are preferably in the form of continuous fibers such as long fibers, woven fabrics, tows and rovings aligned in one direction.

  The carbon fiber bundle used in the present invention needs to have a single fiber fineness of 0.2 to 2.0 dtex, preferably 0.4 to 1.8 dtex. If it is less than 0.2 dtex, the carbon fiber bundle may be easily damaged by the contact with the guide roller during twisting, and the same damage may also occur in the impregnation treatment step of the resin composition. If it exceeds 2.0 dtex, the resin composition may not be sufficiently impregnated into the carbon fiber bundle, and as a result, the fatigue resistance may be lowered.

  In the carbon fiber bundle used in the present invention, the number of filaments in one fiber bundle is preferably in the range of 2500 to 50000. When the number of filaments is less than 2500, the fiber arrangement tends to meander and easily cause a decrease in strength. If the number of filaments exceeds 50,000, it is difficult to impregnate the resin during prepreg production or molding. The number of filaments is more preferably in the range of 2800 to 25000.

  Moreover, a preform can be applied as a form of carbon fiber. Here, the preform is usually a laminated fabric base fabric made of carbon fibers of long fibers, a fabric base fabric stitched and integrated with stitch yarns, or a fiber structure such as a three-dimensional fabric or a braided fabric. Means a thing.

  As the epoxy resin (A) used in the present invention, an epoxy resin alone, a copolymer of an epoxy resin and a thermosetting resin, a modified body, a resin blended with two or more kinds, and the like can be used.

  Examples of the thermosetting resin used by copolymerizing with an epoxy resin include unsaturated polyester resins, vinyl ester resins, epoxy resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimides. .

  In the present invention, among epoxy resins, in particular, epoxy resins having amines, phenols and a compound having a carbon-carbon double bond as a precursor are preferably used. Specifically, various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, and triglycidylaminocresol are exemplified as glycidylamine type epoxy resins having amines as precursors. Tetraglycidyldiaminodiphenylmethane is particularly preferably used as an epoxy resin composition for carbon fiber composite materials used for aircraft structural materials and the like because of its excellent heat resistance. Further, glycidyl aniline type epoxy resin, liquid bisphenol A type epoxy resin, and liquid bisphenol F type epoxy resin are particularly preferably used in combination with traglycidyl diaminodiphenylmethane.

  A glycidyl ether type epoxy resin having phenol as a precursor is also preferably used. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and resorcinol type epoxy resins.

  Since the liquid bisphenol A type epoxy resin, bisphenol F type epoxy resin and resorcinol type epoxy resin have low viscosity, it is preferable to use them in combination with other epoxy resins.

  In addition, the solid bisphenol A type epoxy resin gives a structure having a lower crosslink density compared to the liquid bisphenol A type epoxy resin, so that the heat resistance is low, but a tougher structure is obtained, so that a glycidylamine type epoxy resin is obtained. Or liquid bisphenol A type epoxy resin or bisphenol F type epoxy resin.

  An epoxy resin having a naphthalene skeleton provides a cured resin having a low water absorption and high heat resistance. Biphenyl type epoxy resins, dicyclopentadiene type epoxy resins, phenol aralkyl type epoxy resins and diphenylfluorene type epoxy resins are also preferably used because they give a cured resin having a low water absorption rate. Urethane-modified epoxy resins and isocyanate-modified epoxy resins give cured resins having high fracture toughness and high elongation.

  These epoxy resins may be used alone or in combination as appropriate. The blending of at least a bifunctional epoxy resin and a trifunctional or higher functional epoxy resin has both the fluidity of the resin and the heat resistance after curing. In particular, the combination of glycidylamine type epoxy and glycidyl ether type epoxy makes it possible to achieve both heat resistance and water resistance and processability. In addition, blending at least one epoxy resin that is liquid at room temperature and at least one epoxy resin that is solid at room temperature makes the prepreg tack and drape suitable.

  Phenol novolac type epoxy resins and cresol novolac type epoxy resins have high heat resistance and low water absorption, and thus give a cured resin having high heat resistance and water resistance. By using these phenol novolac-type epoxy resins and cresol novolac-type epoxy resins, the tackiness and draping properties of the prepreg can be adjusted while improving the heat and water resistance.

  Commercially available products of bisphenol A type epoxy resin include “jER (registered trademark)” 825 and “jER (registered trademark)” 834 (both manufactured by Japan Epoxy Resin Co., Ltd.), “Epicron (registered trademark)” 850 ( Dainippon Ink Chemical Co., Ltd.), “Epototo (registered trademark)” YD-128 (manufactured by Toto Kasei Co., Ltd.), DER-331 and DER-332 (all of which are manufactured by Dow Chemical Co., Ltd.). .

  As commercial products of bisphenol F type epoxy resin, “jER (registered trademark)” 806, “jER (registered trademark)” 807 and “jER (registered trademark)” 1750 (all of which are manufactured by Japan Epoxy Resins Co., Ltd.), “Epiclon” 830 (manufactured by Dainippon Ink & Chemicals, Inc.), “Epototo (registered trademark)” YD-170 (manufactured by Toto Kasei Co., Ltd.), and the like.

  Examples of commercially available resorcinol-type epoxy resins include “Deconal (registered trademark)” EX-201 (manufactured by Nagase ChemteX Corporation).

  Commercially available epoxy resins of the tetraglycidyldiaminodiphenylmethane type include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldite (registered trademark)” MY720, “Araldite (registered trademark)” MY721, “Araldite (registered trademark)” MY9512 and “Araldite (registered trademark)” MY9663 (all of which are manufactured by Vantico), “Epototo (registered trademark)” YH-434 (manufactured by Tohto Kasei Co., Ltd.), and the like.

  Commercially available aminophenol type epoxy resins include ELM120 and ELM100 (all of which are manufactured by Sumitomo Chemical Co., Ltd.), “Epicoat (registered trademark)” 630 (manufactured by Japan Epoxy Resin Co., Ltd.), and “Araldite (registered trademark). ) "MY0510 (manufactured by Vantico)".

  Examples of commercially available glycidyl aniline type epoxy resins include GAN and GOT (all of which are manufactured by Nippon Kayaku Co., Ltd.).

  Examples of commercially available biphenyl type epoxy resins include NC-3000 (manufactured by Nippon Kayaku Co., Ltd.).

  Examples of commercially available dicyclopentadiene type epoxy resins include HP7200 (manufactured by Dainippon Ink & Chemicals, Inc.).

  Examples of commercially available urethane-modified epoxy resins include AER4152 (manufactured by Asahi Kasei Epoxy Corporation).

  Examples of commercially available phenol novolac type epoxy resins include DEN431 and DEN438 (all of which are manufactured by Dow Chemical Co., Ltd.) and “Epicoat (registered trademark)” (manufactured by Japan Epoxy Resins Co., Ltd.).

  The (B) curing agent used in the present invention is an epoxy resin curing agent and is a compound having an active group capable of reacting with an epoxy group. Examples of the curing agent include dicyandiamide, various isomers of diaminodiphenylmethane and diaminodiphenylsulfone, aminobenzoic acid esters, various acid anhydrides, phenol novolac resins, cresol novolac resins, polyphenol compounds, imidazole derivatives, aliphatic amines, tetraamines, and the like. Examples include methylguanidine, thiourea addition amine, carboxylic acid anhydride such as methylhexahydrophthalic anhydride, carboxylic acid hydrazide, carboxylic acid amide, polymercaptan, and Lewis acid complex such as boron trifluoride ethylamine complex. .

  It is particularly preferable to use an aromatic diamine as a curing agent because an epoxy resin cured product having good heat resistance can be obtained. In particular, various isomers of diaminodiphenylsulfone are most suitable for obtaining a cured epoxy resin having good heat resistance.

  Further, by using a combination of dicyandiamide and a urea compound such as 3,4-dichlorophenyl-1,1-dimethylurea or imidazoles as a curing agent, high heat resistance and water resistance can be obtained while curing at a relatively low temperature. . Curing the epoxy resin with an acid anhydride gives a cured product having a lower water absorption than the amine compound curing. In addition, by using a latent product of these curing agents, for example, a microencapsulated product, the storage stability of the prepreg, in particular, tackiness and draping properties hardly change even when left at room temperature.

  The optimum value of the amount added depends on the type of epoxy resin and curing agent. For example, in the case of an aromatic amine curing agent, it is preferable to add it so as to be stoichiometrically equivalent, but by using an equivalent ratio of about 0.7 to 0.8, a higher elastic modulus resin than when used in an equivalent amount. Is also a preferred embodiment. These curing agents may be used alone or in combination.

  Examples of commercially available aromatic amine curing agents include “SumiCure (registered trademark)” S (manufactured by Sumitomo Chemical Co., Ltd.), MDA-220 (manufactured by Mitsui Chemicals Fine Co., Ltd.), and “Epicure (registered trademark)”. W (manufactured by Japan Epoxy Resin Co., Ltd.), 3,3′-DAS (manufactured by Mitsui Chemicals, Inc.), and the like.

  Moreover, the thing which made these epoxy resin and hardening | curing agent, or some of them pre-react can be mix | blended in a composition. This method may be effective for viscosity adjustment and storage stability improvement.

  In the present invention, it is also preferable to mix or dissolve the thermoplastic resin in (A) the epoxy resin. Such thermoplastic resins are generally selected from the group consisting of carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, thioether bonds, sulfone bonds and carbonyl bonds in the main chain. A thermoplastic resin having a selected bond is preferable, but it may have a partially crosslinked structure. Further, it may be crystalline or amorphous. In particular, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having phenyltrimethylindane structure, polysulfone, polyethersulfone, polyetherketone, polyetherether It is preferable that at least one resin selected from the group consisting of ketone, polyaramid, polyether nitrile, and polybenzimidazole is mixed or dissolved in the epoxy resin.

  As these thermoplastic resins, commercially available polymers may be used, or so-called oligomers having a molecular weight lower than that of commercially available polymers may be used. As the oligomer, an oligomer having a functional group capable of reacting with an epoxy resin at a terminal or in a molecular chain is preferable.

  Mixtures of epoxy resins and thermoplastic resins give better results than using them alone. The brittleness of the epoxy resin is covered with the toughness of the thermoplastic resin, and the molding difficulty of the thermoplastic resin is covered with the epoxy resin, thereby providing a balanced base resin. The use ratio (parts by mass) of the epoxy resin and the thermoplastic resin is preferably in the range of 100: 2 to 100: 50, more preferably in the range of 100: 5 to 100: 35 in terms of balance.

  In the present invention, (C) the conductive substance-containing thermoplastic resin particles are used as an essential component, so that the resulting carbon fiber reinforced composite material can achieve excellent impact resistance. The thermoplastic resin material of the conductive material-containing thermoplastic resin particle (C) used in the present invention is the same thermoplastic as the various thermoplastic resins that can be used by mixing or dissolving in the epoxy resin exemplified above. Resin can be used. Among these, polyamide is most preferable and greatly improves the adhesion with the matrix resin. Among polyamides, nylon 6, nylon 66, nylon 12, nylon 11 and nylon 6/12 copolymer give particularly good adhesive strength with thermosetting resins.

  In addition, when carbon fiber is impregnated with the epoxy resin composition for carbon fiber reinforced composite material of the present invention to obtain a prepreg, the content of the conductive substance-containing thermoplastic resin particles is 1 to 10 in 100% by mass of the prepreg. It is preferably in the range of mass%. If the content of the conductive material-containing thermoplastic resin particles exceeds 10% by mass with respect to the prepreg, the tackability and draping properties of the prepreg may decrease, and the handleability may tend to deteriorate. In order to obtain high impact resistance, the amount of the conductive substance-containing thermoplastic resin particles is preferably 1% by mass or more, more preferably 2% by mass or more based on the prepreg.

  The conductive material of the conductive material-containing thermoplastic particles (C) used in the present invention is only required to contain a material that is an electrically good conductor. For example, gold, silver, copper, platinum, nickel, Metals such as palladium and cobalt, conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyisothianaphthene, and polyethylenedioxythiophene, carbon black such as channel black, thermal black, furnace black, and ketjen black, carbon nanotubes Carbon such as fullerene, graphene, and hollow carbon fiber can be used. Among these, carbon black is particularly preferably used since it exhibits high conductivity and stability.

  The content of the conductive substance in the conductive substance-containing thermoplastic resin particles is preferably 10 to 80% by mass, more preferably 20 to 80% by mass with respect to the conductive substance-containing thermoplastic resin particles. . If the amount is less than 10% by mass, the conductivity of the carbon fiber reinforced composite material may not be good. If the amount exceeds 80% by mass, the properties of the thermoplastic resin may not be exhibited.

  Note that the thermoplastic resin particles (C) containing the conductive material (conductive material-containing thermoplastic resin particles) of the present invention are different from the particles in which the conductive material is coated on the surface of the thermoplastic resin. And the conductive material are kneaded by a technique such as extrusion, and then pulverized or granulated by a chemical technique, and the conductive material is contained inside or on the surface of the particle. In the present invention, by using such particles, the thermoplastic resin is easily deformed during the curing process of the carbon fiber reinforced composite material, and a conductive material layer having the same size as the layers of the carbon fiber reinforced composite material is formed. Therefore, it is easy to efficiently dispose the conductive material between the layers, and the conductivity of the carbon fiber reinforced composite material tends to be high. On the other hand, in the conventionally used coated particles, when the core thermoplastic resin is deformed, the coated conductive material is cracked, and the conductivity of the carbon fiber reinforced composite material is lowered.

  The glass transition temperature of the thermoplastic resin used for the conductive material-containing thermoplastic resin particles is preferably a thermoplastic resin having a glass transition temperature of 180 ° C. or lower, more preferably 100 ° C. or lower. When the glass transition temperature of the thermoplastic resin of the conductive material-containing thermoplastic resin particles is 180 ° C. or less, the thermoplastic resin is likely to be deformed during the curing process of the carbon fiber reinforced composite material, and is the same as the interlayer of the carbon fiber reinforced composite material. Since it is possible to form a layer of a conductive material having a size, the conductivity of the carbon fiber reinforced composite material tends to be high.

  The conductive material-containing thermoplastic resin particles may be spherical particles, non-spherical particles, or porous particles, but particles having a shape close to spherical particles are superior in viscoelasticity because they do not deteriorate the flow characteristics of the resin, Further, this is a preferred embodiment in that there is no starting point of stress concentration and high impact resistance is imparted.

  In the prepreg of the present invention, when the thermoplastic resin particles and the conductive material-containing thermoplastic particles are used in combination, the average particle size of the conductive material-containing thermoplastic resin particles is the same as the average particle size of the thermoplastic resin particles, or It is preferably larger than the average particle diameter of the thermoplastic resin particles. When the average particle size of the conductive material-containing thermoplastic resin particles is smaller than the average particle size of the thermoplastic resin particles, the conductive material-containing thermoplastic resin particles are buried between the layers, which does not provide a sufficient conductivity improvement effect. Sometimes.

  In the present invention, the average particle size of the conductive substance-containing thermoplastic resin particles is preferably smaller than 150 μm. If the average particle size is too large, the arrangement of the carbon fibers may be disturbed, and if the particle layer is formed in the vicinity of the surface of the prepreg as described later, the layers of the obtained carbon fiber reinforced composite material In order to make it thicker than necessary, the physical properties of the carbon fiber reinforced composite material may be lowered. The average particle size is preferably 1 to 150 μm, more preferably 3 to 60 μm, and particularly preferably 5 to 30 μm. By setting the average particle size to a certain value or more, it is possible to prevent particles from entering between the fibers of the carbon fiber, and also to prevent localization of the particles in the interlayer portion of the prepreg laminate. As a result, the obtained carbon fiber reinforced composite material can easily have both excellent conductivity and impact resistance.

  The average particle size described here is specified as follows. That is, the particles are magnified 1000 times or more with a microscope such as a scanning electron microscope and photographed, the particles are randomly selected, the diameter of the circle circumscribing the particles is taken as the particle size, and the average value (n = 50) is the average particle size of the particles.

  The content of the conductive substance-containing thermoplastic resin particles is preferably 0.01 to 50% by mass, more preferably 1 to 30% by mass, based on the total amount of the epoxy resin composition for carbon fiber reinforced composite material of the present invention. More preferably, it is 5-20 mass%. If the content of the conductive material-containing thermoplastic resin particles is small, sufficient conductivity may not be obtained. If the content is too large, the viscosity of the matrix resin may increase and the handling property of the matrix resin may decrease. .

  In the present invention, when the thermoplastic resin particles and the conductive substance-containing thermoplastic resin particles are used in combination, [the amount of the thermoplastic resin particles (parts by mass)] / [the blend of the conductive substance-containing thermoplastic resin particles] The mass ratio represented by the amount (parts by mass)] is preferably 1 to 1000, more preferably 5 to 200, and particularly preferably 10 to 100. When the mass ratio is less than 1, sufficient impact resistance may not be obtained, and when the mass ratio is greater than 1000, sufficient conductivity may not be obtained.

  In obtaining the epoxy resin composition for carbon fiber reinforced composite material of the present invention, it is also preferable to use a masterbatch composed of epoxy resin and conductive material-containing thermoplastic resin particles. That is, depending on the mixing method, the original mechanical properties and conductivity may not be exhibited due to the presence of aggregates of conductive resin-containing thermoplastic resin particles, whereas in the resin composition by using a master batch. The mixing of coarse aggregates into the resin composition is suppressed, and the dispersibility in the resin composition is improved. By improving the dispersibility, the conductivity and mechanical properties of the carbon fiber reinforced composite material of the present invention are stabilized and variations are reduced. Also, if the mass ratio of the epoxy resin amount is too small, the dispersibility of the conductive substance-containing thermoplastic resin particles may be deteriorated. Conversely, if the mass ratio of the epoxy resin is larger than this range, the master batch method is used. Usefulness may be reduced.

  As an application method of the masterbatch, for example, the following procedure is given as an example. First, knead the epoxy resin and conductive material-containing thermoplastic resin particles with a stirrer, disperse the conductive material-containing thermoplastic resin particles to prepare a masterbatch, and make the mass ratio of the designed epoxy resin composition The target epoxy resin composition for a carbon fiber composite material can be obtained by adding the prepared master batch to the remaining epoxy resin, thermoplastic resin, curing agent and the like.

  In order to obtain the epoxy resin composition for carbon fiber reinforced composite material of the present invention, components other than the thermoplastic resin particles and the curing agent are uniformly heated and kneaded at about 150 ° C. and cooled to a temperature at which the curing reaction does not proceed easily. Although it is preferable to add and knead the thermoplastic resin particles and the curing agent, the blending method of each component is not particularly limited to this method.

  The prepreg according to the present invention is obtained by impregnating carbon fibers with the above epoxy resin composition for carbon fiber reinforced composite materials. The carbon fiber mass fraction of the prepreg is preferably 40 to 90% by mass, and more preferably 50 to 80% by mass. If the carbon fiber mass fraction is too low, the mass of the resulting carbon fiber reinforced composite material may be excessive, and the advantages of the fiber reinforced composite material having excellent specific strength and specific modulus may be impaired. If the rate is too high, poor impregnation of the resin will occur, and the resulting carbon fiber reinforced composite material will tend to have many voids, and its mechanical properties may be greatly degraded.

  In the prepreg of the present invention, when the particle-rich layer, that is, the cross section thereof is observed, the above-described particles (conductive substance-containing thermoplastic resin particles, thermoplastic resin particles) are present in a localized state. It is preferable that the layer (hereinafter sometimes abbreviated as a particle layer) that can be clearly confirmed has a structure formed in the vicinity of the surface of the prepreg.

  In this way, by taking a structure in which particles are unevenly distributed on the surface side, when a prepreg is laminated and an epoxy resin is cured to form a carbon fiber reinforced composite material, the prepreg layer, that is, the carbon fiber reinforced composite material layer A resin layer is easily formed between them, whereby the adhesion and adhesion between the carbon fiber reinforced composite material layers are enhanced, and the resulting carbon fiber reinforced composite material exhibits high impact resistance.

  From such a viewpoint, the particle layer is preferably 20% deep, more preferably 10% deep from the surface of the prepreg in the thickness direction starting from the surface with respect to 100% of the thickness of the prepreg. It is preferable that it exists in the range. In addition, the particle layer may exist only on one side, but since the prepreg can be front and back, care must be taken in the lamination. If the layers of the prepreg are mistaken and there are layers with and without particles, a carbon fiber reinforced composite material that is weak against impacts is obtained. In order to eliminate the distinction between front and back and facilitate lamination, the particle layer should be present on both the front and back sides of the prepreg.

  Furthermore, the abundance ratio of the thermoplastic resin particles and the conductive material-containing thermoplastic resin particles present in the particle layer is 100% by mass of the total amount of the thermoplastic resin particles and the conductive material-containing thermoplastic resin particles in the prepreg. , Preferably it is 90-100 mass%, More preferably, it is 95-100 mass%.

  The abundance of the particles can be evaluated by, for example, the following method. That is, the prepreg is sandwiched between two smooth polytetrafluoroethylene resin plates with a smooth surface, and the temperature is gradually raised to the curing temperature over 7 days to gel and cure to cure the plate-like prepreg. Make a thing. Two lines parallel to the surface of the prepreg are drawn on both surfaces of the prepreg cured product from the surface of the prepreg cured product at a depth of 20% of the thickness. Next, the total area of the particles existing between the surface of the prepreg and the line and the total area of the particles existing over the thickness of the prepreg are obtained, and from the surface of the prepreg with respect to 100% of the thickness of the prepreg. Calculate the abundance of particles present in the 20% depth range. Here, the total area of the particles is obtained by cutting out the particle portion from the cross-sectional photograph and converting it from the mass. If it is difficult to discriminate the particles dispersed in the resin after photography, a means for dyeing the particles can also be employed.

  In the present invention, the amount of the conductive substance-containing thermoplastic resin particles is preferably in the range of 20% by mass or less based on the prepreg. When it exceeds 20 mass% with respect to a prepreg, mixing of particle | grains and resin will become difficult, and the tack | tuck and drape property of a prepreg may fall. That is, in order to provide impact resistance by particles while maintaining the properties of the epoxy resin as the base resin, the amount of the conductive material-containing thermoplastic resin particles should be 20% by mass or less based on the prepreg. Preferably, it is 15 mass% or less more preferably. In order to further improve the handling of the prepreg, the amount of the conductive substance-containing thermoplastic resin particles is preferably 10% by mass or less. The amount of the particles is preferably 1% by mass or more, more preferably 2% by mass or more with respect to the prepreg in order to obtain high impact resistance and conductivity.

  The prepreg of the present invention can be produced by applying a method as disclosed in JP-A-1-26651, JP-A-63-170427 or JP-A-63-170428. Specifically, the prepreg of the present invention is a method in which the conductive resin-containing thermoplastic resin particles and the thermoplastic resin particles are directly applied to the surface of a primary prepreg composed of carbon fiber and an epoxy resin that is a matrix resin. A conductive resin-containing thermoplastic resin is reinforced with a fiber prepared by uniformly mixing a mixture of these conductive substance-containing thermoplastic resin particles and thermoplastic resin particles in a certain epoxy resin, and impregnating the mixture into carbon fibers. A method of blocking the invasion of particles and thermoplastic resin particles to localize the particles on the surface portion of the prepreg, or preparing a primary prepreg by impregnating carbon fiber with an epoxy resin in advance, and the surface of the primary prepreg It can manufacture by the method of sticking the film of the thermosetting resin which contains these particle | grains in high concentration. Conductive substance-containing thermoplastic resin particles and thermoplastic resin particles are uniformly present in the depth range of 20% of the prepreg thickness, so that the prepreg for carbon fiber composite material having both impact resistance and conductivity is provided. Is obtained.

  The carbon fiber reinforced composite material of the present invention can be produced by taking, as an example, a method of laminating the above-described prepreg of the present invention in a predetermined form and curing the resin by pressurization and heating. Use of a combination of thermoplastic resin particles and conductive resin-containing thermoplastic resin particles reduces delamination caused by local impacts when falling weight impacts (or local impacts) on carbon fiber reinforced composite materials Therefore, when stress is applied to the carbon fiber reinforced composite material after such an impact, there are few delamination portions caused by the local impact that becomes the starting point of fracture due to stress concentration, or conductive materials. Since the contained thermoplastic resin particles have a high contact probability with the carbon fibers in the laminated layer and easily form a conductive path, a carbon fiber reinforced composite material that exhibits high impact resistance and conductivity can be obtained.

  Further, a method for directly curing the epoxy fiber composition for carbon fiber reinforced composite material of the present invention without using a prepreg, followed by heat curing, such as a hand layup method, a filament winding method, a pultrusion method. The carbon fiber reinforced composite material can also be produced by a molding method such as a resin method, a resin injection molding method, or a resin transfer molding method.

  The carbon fiber reinforced composite material of the present invention is preferably used for computer applications such as aircraft structural members, windmill blades, automobile outer plates, IC trays, and housings (housings) of notebook computers.

  Hereinafter, the epoxy resin composition for carbon fiber reinforced composite material of the present invention, the prepreg using the same, and the carbon fiber reinforced composite material will be described more specifically with reference to examples. The resin raw materials, prepregs and carbon fiber reinforced composite materials used in the examples, and methods for evaluating post-impact compressive strength are shown below. The production environment and evaluation of the prepregs of the examples are performed in an atmosphere at a temperature of 25 ° C. ± 2 ° C. and a relative humidity of 50% unless otherwise specified. Further, the present invention is not limited to these examples.

<Carbon fiber>
"Torayca (registered trademark)" T800S-24K-10E (24,000 fibers, tensile strength 5.9 GPa, tensile elastic modulus 290 GPa, tensile elongation 2.0% carbon fiber, total fineness 1.03 g / m , Manufactured by Toray Industries, Inc.).

<Epoxy resin>
・ Bisphenol A type epoxy resin, "jER (registered trademark)" 825 (manufactured by Japan Epoxy Resin Co., Ltd.)
Tetraglycidyldiaminodiphenylmethane, ELM434 (manufactured by Sumitomo Chemical Co., Ltd.).

<Curing agent>
-4,4'-diaminodiphenyl sulfone (made by Mitsui Chemicals Fine Co., Ltd.).

<Thermoplastic resin>
-Polyethersulfone having a hydroxyl group at the terminal "SUMICA EXCEL (registered trademark)" PES5003P (manufactured by Sumitomo Chemical Co., Ltd.).

<Thermoplastic resin particles>
・ Nylon 12 particles SP-10 (manufactured by Toray Industries, Inc., shape: true sphere)
-Epoxy-modified nylon particles A obtained by the following production method
90 parts by mass of transparent polyamide (trade name “Grillamide (registered trademark)”-TR55, manufactured by Mzavelke), 7.5 parts by mass of epoxy resin (product name “jER (registered trademark)” 828, manufactured by Japan Epoxy Resin Co., Ltd.) And 2.5 parts by mass of a curing agent (trade name “Tomide (registered trademark)” # 296, manufactured by Fuji Kasei Kogyo Co., Ltd.) in a mixed solvent of 300 parts by mass of chloroform and 100 parts by mass of methanol, A homogeneous solution was obtained. Next, the obtained uniform solution was atomized using a spray gun for coating, well stirred, and sprayed toward the liquid surface of 3000 parts by mass of n-hexane to precipitate a solute. The precipitated solid was separated by filtration and washed well with n-hexane, followed by vacuum drying at 100 ° C. for 24 hours to obtain epoxy-modified nylon particles A. (Average particle size: 12.5 μm).

<Conducting substance-containing thermoplastic resin particles>
-Nylon 6 particles containing 20% carbon black (glass transition temperature: 48 ° C., average particle size: 25 μm)
-Nylon 6 particles containing 50% carbon black (glass transition temperature: 48 ° C., average particle size: 25 μm)
・ Nylon 12 particles containing 20% carbon black (glass transition temperature: 50 ° C., average particle size: 25 μm)
・ Nylon 12 particles containing 50% carbon black (glass transition temperature: 50 ° C., average particle size: 25 μm)
・ Nylon 11 particles containing 20% carbon black (glass transition temperature: 37 ° C., average particle size: 25 μm)
・ Nylon 11 particles containing 50% carbon black (glass transition temperature: 37 ° C., average particle size: 25 μm)
-Nylon 66 particles containing 20% carbon black (glass transition temperature: 50 ° C., average particle size: 25 μm)
-Nylon 66 particles containing 50% carbon black (glass transition temperature: 50 ° C., average particle size: 25 μm)
The conductive material-containing thermoplastic resin particles were obtained by pulverization or a chemical technique after a thermoplastic resin and carbon black were kneaded by extrusion to obtain a thermoplastic resin containing carbon black.

  As carbon black, furnace black (# 3030B) manufactured by Mitsubishi Chemical Corporation was used. As thermoplastic resins, nylon 6 is A1030BRL manufactured by Unitika Ltd., nylon 12 is nylon 12 ("UBESTA (registered trademark)"-3020JX6) manufactured by Ube Industries, Ltd., and nylon 11 is undecane lactam. A125 produced by Unitika Co., Ltd. was used as nylon 11 and nylon 66 with ηr = 2.3 obtained by ring-opening polymerization.

<Conductive particles>
“Micropearl (registered trademark)” AU215 (average particle diameter: 15.5 μm) (the same conductive particles as those described in Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 2008-232395))
“Micropearl (registered trademark)” CU215 (average particle diameter: 15.5 μm) (conductive particles identical to the conductive particles described in Example 13 of Patent Document 5 (Japanese Patent Laid-Open No. 2009-077405)).

<Coupling agent>
-Z-6011 (made by Toray Dow Corning Co., Ltd.): 3-aminopropyltriethoxysilane.

<Conductive film>
Conductive film described in Example 10 of conductive film B (thickness: 13.7 μm, volume resistivity: 3.8 × 10 ⁻⁵ Ωcm) (Patent Document 4 (Japanese Patent Laid-Open No. 2009-062473)) The same conductive film).

(1) Presence of particles existing in a 20% depth range of prepreg The prepreg is sandwiched between two smooth polytetrafluoroethylene resin plates on the surface and brought into close contact, and gradually over 7 days. The temperature was raised to 150 ° C. and gelled and cured to produce a plate-shaped resin cured product. After curing, the film was cut from the direction perpendicular to the contact surface, and the cross-section was polished, then magnified 200 times or more with an optical microscope, and photographed so that the upper and lower surfaces of the prepreg were within the visual field. By the same operation, the distance between the polytetrafluoroethylene resin plates was measured at five locations in the horizontal direction of the cross-sectional photograph, and the average value (n = 5) was taken as the thickness of the prepreg.

  On both sides of the prepreg, two lines parallel to the surface of the prepreg were drawn from the surface of the prepreg at a depth of 20% of the thickness. Next, the total area of the particles existing between the surface of the prepreg and the line and the total area of the particles existing over the thickness of the prepreg are obtained, and from the surface of the prepreg with respect to 100% of the thickness of the prepreg. The abundance of particles present in the 20% depth range was calculated. The total area of the fine particles was obtained by cutting out the particle portion from the cross-sectional photograph and converting from the mass. When it was difficult to discriminate the particles dispersed in the matrix resin after photography, a means for staining the particles was used.

(2) Measurement of compressive strength after impact of fiber reinforced composite material [+ 45 ° / 0 ° / −45 ° / 90 °] A unidirectional prepreg is laminated in a pseudo-isotropic 24 ply with a _3S configuration and is autoclaved. 25 laminates were produced by molding at a temperature of 180 ° C. for 2 hours under a pressure of 0.59 MPa and at a heating rate of 1.5 ° C./min. A sample 150 mm long × 100 mm wide (thickness 4.5 mm) was cut out from each of these laminates, and a falling weight impact of 6.7 J / mm was applied to the center of the sample according to SACMA SRM 2R-94, and compression after impact was performed. The strength was determined.

(3) Conductivity measurement of fiber reinforced composite material Each unidirectional prepreg is [+ 45 ° / 0 ° / −45 ° / 90 °] in a _2S configuration, and is quasi-isotropically laminated with 16 plies, and is 180 by an autoclave. 25 laminates were produced by molding at a temperature of 1.5 ° C. for 2 hours under a pressure of 0.59 MPa at a temperature rising rate of 1.5 ° C./min. From each of these laminates, a sample having a length of 50 mm × width 50 mm (thickness 3 mm) was cut out and a sample in which a conductive paste “Dotite (registered trademark)” D-550 (manufactured by Fujikura Kasei Co., Ltd.) was applied to both sides was prepared. did. These samples were measured for resistance in the stacking direction by a four-terminal method using an R6581 digital multimeter manufactured by Advantest Corp. to determine volume resistivity.

Example 1
In a kneading apparatus, 50 parts by mass of “jER” 825 and 50 parts by mass of ELM 434 were mixed with 10 parts by mass of PES5003P, and the thermoplastic resin was dissolved in the epoxy resin. Thereafter, 20 parts by mass of carbon black-containing nylon 6 was kneaded, and 40 parts by mass of 4,4′-diaminodiphenyl sulfone as a curing agent was further kneaded to prepare an epoxy resin composition for carbon fiber reinforced composite material.

For the epoxy resin composition for carbon fiber reinforced composite material shown in Table 1 (in the table, the number represents part by mass), a base resin excluding thermoplastic resin particles and conductive substance-containing thermoplastic resin particles was prepared, and a knife A release film was coated on a release paper with a resin basis weight of 31 g / m ² using a coater to prepare a resin film. An epoxy resin composition for a carbon fiber reinforced composite material is obtained by superimposing the resin film on both sides of a carbon fiber (weight per unit area 190 g / m ² ) aligned in one direction and using a heat roll while heating and pressing at 100 ° C. and 1 atm. Was impregnated to obtain a primary prepreg.

Next, an epoxy resin composition prepared by adding thermoplastic particles and conductive material-containing thermoplastic resin particles so that the epoxy resin composition of the final prepreg for carbon fiber reinforced composite material becomes the blending amount shown in Table 1 Using a knife coater, the release paper was coated with a resin basis weight of 21 g / m ² to prepare a resin film. This resin film was superimposed on both sides of the primary prepreg, and a heat roll was used to impregnate the epoxy resin composition for carbon fiber reinforced composite material while heating and pressing at 100 ° C. and 1 atm to obtain the desired prepreg.

  Using the obtained prepreg, (1) the abundance ratio of particles existing in the depth range of 20% of the thickness of the prepreg, (2) measurement of compressive strength after impact of the fiber reinforced composite material, and (3) fiber reinforced composite The carbon fiber reinforced composite material was obtained as described in the measurement of the conductivity of the material, and the post-impact compressive strength and volume resistivity were measured. The results are shown in Table 1.

(Examples 2 to 13, Comparative Examples 1 to 6)
Tables 1 and 2 show the types and amounts of epoxy resins, curing agents, thermoplastic resins, thermoplastic resin particles, conductive material-containing thermoplastic resin particles, conductive particles, coupling agents, and conductive films. A prepreg was produced in the same manner as in Example 1 except for the change. Using the produced unidirectional prepreg, the abundance of particles existing in the range of 20% depth of the prepreg, the compressive strength after impact of the fiber-reinforced composite material, and the conductivity were measured. The obtained results are summarized in Tables 1 and 2.

  By comparison with Examples 1-13 and Comparative Examples 1-6, the carbon fiber reinforced composite material using the epoxy resin composition for carbon fiber reinforced composite material of the present invention is composed of conductive resin-containing thermoplastic resin particles and matrix resin. It can be seen that the adhesion with the epoxy resin is strong, high compressive strength after impact and low volume resistivity are realized, and both high impact resistance and conductivity are achieved.

  According to the present invention, an epoxy resin composition for a carbon fiber reinforced composite material having excellent mechanical properties and conductivity, a prepreg, and a carbon fiber reinforced composite material can be obtained. In addition, it can be widely used in computer applications such as IC trays and casings (housings) of notebook computers, and is useful.

Claims (10)

An epoxy resin composition for a carbon fiber reinforced composite material, comprising at least (A) an epoxy resin, (B) a curing agent, and (C) thermoplastic resin particles containing a conductive substance. (C) The epoxy resin composition for carbon fiber reinforced composite materials according to claim 1, wherein 0.01 to 50% by mass of thermoplastic resin particles containing a conductive substance is contained in the epoxy resin composition. The epoxy resin composition for carbon fiber-reinforced composite material according to claim 1, wherein the conductive substance is carbon black. The epoxy resin composition for carbon fiber reinforced composite material according to any one of claims 1 to 3, wherein the conductive material is contained in 10 to 80 mass% in the thermoplastic resin particles containing the conductive material (C). object. The epoxy resin composition for carbon fiber-reinforced composite material according to any one of claims 1 to 4, wherein the thermoplastic resin has a glass transition temperature of 180 ° C or lower. (C) The epoxy resin composition for carbon fiber reinforced composite materials according to any one of claims 1 to 5, wherein the average particle diameter of the thermoplastic resin particles containing a conductive substance is smaller than 150 µm. A prepreg obtained by impregnating carbon fiber with the epoxy resin composition for carbon fiber reinforced composite material according to any one of claims 1 to 6. (C) The prepreg of Claim 7 in which the thermoplastic resin particle containing an electroconductive substance is unevenly distributed in the surface side. A carbon fiber reinforced composite material obtained by curing the prepreg according to claim 7. The carbon fiber reinforced composite material which consists of hardened | cured material of the epoxy resin composition for carbon fiber reinforced composite materials in any one of Claim 1 to 6, and carbon fiber.