JP6213225B2 - Prepreg and fiber reinforced composites - Google Patents

Description

  The present invention relates to a prepreg used for obtaining a fiber-reinforced composite material having both excellent conductivity and impact resistance, and a fiber-reinforced composite material using the prepreg.

  Conventionally, fiber-reinforced composite materials made of carbon fiber, glass fiber, and other reinforcing fibers and epoxy resins, phenol resins, and other thermosetting resins are lightweight, yet have mechanical properties such as strength and rigidity, heat resistance, and corrosion resistance. It has been applied to many fields such as aviation / space, automobiles, rail cars, ships, civil engineering and sports equipment. Especially in applications where high performance is required, fiber reinforced composite materials using continuous reinforcing fibers are used, carbon fibers with excellent specific strength and specific elastic modulus are used as reinforcing fibers, and thermosetting is used as a matrix resin. Of these, many epoxy resins are used that are particularly excellent in adhesion to carbon fibers.

  However, a cured product of a thermosetting resin such as an epoxy resin generally has a lower fracture toughness than a thermoplastic resin. This causes a problem that the impact resistance of the fiber reinforced composite material is lowered. In particular, in the case of aircraft structural members, improvement in impact resistance has been a major issue because excellent impact resistance is required against tool dropping during assembly and impact of a kite during operation.

  The fiber reinforced composite material generally has a layer structure. When an impact is applied to the fiber reinforced composite material, a high stress is applied between the layers, and a crack is generated. In order to suppress the occurrence of cracks, it is effective to increase the plastic deformation ability of the epoxy resin, and as a means therefor, a thermoplastic resin having an excellent plastic deformation ability is blended.

  Various methods have been studied in the past for blending thermoplastic resins. For example, as described in Patent Documents 1 and 2, there is a method of using, as a matrix resin, a high toughness thermosetting resin obtained by dissolving a thermoplastic resin in a thermosetting resin to increase the toughness.

  Further, as another means for improving impact resistance, as described in Patent Document 3 or 4, there is known a technique in which a thermoplastic resin is present between layers where cracks easily occur.

  However, such a technique gives a high impact resistance to the fiber reinforced composite material, while generating a resin layer serving as an insulating layer between the layers. Therefore, among the electrical conductivity that is one of the characteristics of the fiber-reinforced composite material, there is a drawback that the electrical conductivity in the thickness direction is significantly reduced.

  As a method for increasing the electrical conductivity in the thickness direction of the fiber reinforced composite material, for example, as described in Patent Document 5 or 6, a method of blending metal particles or carbon particles into a matrix resin is considered. The literature does not mention any compatibility between high impact resistance and electrical conductivity, and it has been difficult to achieve both excellent impact resistance and electrical conductivity in fiber reinforced composite materials.

  In recent years, intensive studies have been made to achieve both excellent impact resistance and electrical conductivity in fiber reinforced composite materials. For example, as described in Patent Document 7 or 8, there is a method of arranging a reinforcing material that improves impact resistance and conductive particles that improve conductivity in an interlayer portion of a fiber reinforced composite material.

  However, the effect of improving the conductivity by these methods is not sufficient, and further improvement is required. Therefore, in order to improve conductivity, a conductive filler such as carbon black may be mixed in the matrix resin in addition to the conductive particles. However, if the dispersion of the conductive filler in the matrix resin is not uniform, the impact resistance and tensile strength of the carbon fiber reinforced composite material are lowered. In order to achieve both excellent impact resistance and conductivity, a carbon fiber composite material in which a conductive filler is uniformly dispersed in a matrix resin is required. Moreover, the fiber reinforced composite material needs to appropriately adjust the basis weight of the carbon fiber and the fiber volume content according to the purpose depending on the application or part to which the fiber reinforced composite material is applied. In such a case, if the size of the impact resistance reinforcing material or conductive particles is not adjusted, the desired conductivity cannot be obtained, or the fiber volume content required for the applied member is not satisfied, resulting in a decrease in physical properties. Or the mass of the member may increase.

  As described above, it is necessary to obtain a fiber-reinforced composite material that achieves both excellent impact resistance and conductivity even if the carbon fiber basis weight is changed according to the purpose.

Japanese Patent Laid-Open No. 62-297314 JP-A 62-297315 JP-A-01-104624 Japanese Patent Laid-Open No. 02-311538 Japanese Patent Laid-Open No. 06-344519 Japanese Patent Laid-Open No. 08-034864 JP 2008-231395 A Special table 2010-508416

  An object of the present invention is to provide a prepreg capable of obtaining a fiber-reinforced composite material having both excellent electrical conductivity and impact resistance in the thickness direction even if the basis weight of the carbon fiber changes depending on the member to be applied.

The present invention employs the following means in order to solve such problems. That is, a prepreg including the following constituent elements [A] to [G], a range corresponding to an average thickness of 13% of the prepreg from the surface of the prepreg is configured by the constituent elements [B] to [G]. 85% by mass or more of each of the constituent elements [E] and [F] is present in a range corresponding to 15% of the average thickness of the prepreg from the surface of the prepreg, and the constituent elements [B] to [D ] And [G] are prepregs satisfying the following condition (I).
[A]: Carbon fiber [B]: Epoxy resin having two or more glycidyl groups in one molecule [C]: Aromatic amine compound [D]: Thermoplastic resin composed of a polyaryl ether skeleton [E] Particles having a number average particle size of primary particles of 5 to 50 μm and having thermoplastic resin as a main component [F]: Conductive particles having a number average particle size of primary particles in the range of the following formula (1) [(F × 0.12) −3] ≦ P _size ≦ [(F × 0.12) +3] (1)
P _size : number average particle size (μm) of primary particles of conductive particles as constituent element [F]
F: Weight of component [A] in prepreg (g / m ² )
[G]: Carbon black in which the number average particle diameter of primary particles is 10 to 50 nm, and the size of the structure in which a plurality of primary particles are combined in the constituent element [B] is 100 to 500 nm. ): Component [C] in which the ratio of the number of epoxy groups in component [B] to the number of active hydrogens in component [C] is 1: 1 (0.7 ≦ l ≦ 1.3), Component [D] with a blending amount of m parts by mass (5 ≦ m ≦ 40) with respect to 100 parts by mass of component [B], and n parts by mass (1 ≦ n with respect to 100 parts by mass of component [B] The viscosity at a temperature of 70 ° C. of the resin composition composed of the constituent elements [B], [C], [D] and [G] including the constituent element [G] having a blending amount of ≦ 5) is 10 to 500 Pa · s. L, m, and n exist.

  According to a preferred embodiment of the prepreg of the present invention, the component [G] is contained in an amount of 1 to 5 parts by mass with respect to 100 parts by mass of the component [B], and another preferred embodiment is the component [F]. Are carbon particles, 0.5 to 10 parts by mass with respect to 100 parts by mass of the component [B], and particles mainly composed of the thermoplastic resin of the component [E] The particles are in the range of 95: 5 to 70: 30% by mass of the curable resin, the thermoplastic resin constituting the constituent element [E] is a polyamide, and the constituent element [A] The fiber volume content (Vf) is 50 to 65% by volume.

In a preferred method for producing the prepreg of the present invention, a part of the component [B] and the component [G] are pre-kneaded to prepare a master batch comprising the component [B] and the component [G]. The master batch is mixed with the rest of the component [B] and the components [C] to [F] and then impregnated into the component [A]. Another preferred production method is The compounding ratio is 5 to 50 parts by mass of the component [G] with respect to 100 parts by mass of the component [B], and a structure in which a plurality of primary particles of the component [G] are bonded in the master batch. The surface resistivity of the master batch is 1 × 10 ⁶ Ω or less.

  The fiber-reinforced composite material of the present invention is obtained by heat-curing the prepreg of the present invention. According to a preferred embodiment, the volume resistivity in the thickness direction of the fiber-reinforced composite material is 10 Ωcm or less, and a more preferred embodiment Has a post-impact compressive strength (CAI) of 280 MPa or more.

  By laminating and curing the prepreg of the present invention, it has become possible to provide a fiber reinforced composite material having both excellent conductivity in the thickness direction and impact resistance. The prepreg of the present invention has excellent electrical conductivity and impact resistance in the thickness direction even with respect to various carbon fiber basis weights, so that it can be used for aircraft structural members, windmill blades, automobile outer plates, IC trays and laptop computers. It can be widely deployed in computer applications such as housings, and the performance of applicable products can be greatly improved.

The prepreg of the present invention includes the following components [A] to [G].
[A]: Carbon fiber [B]: Epoxy resin having two or more glycidyl groups in one molecule [C]: Aromatic amine compound [D]: Thermoplastic resin composed of a polyaryl ether skeleton [E] Particles having a number average particle size of primary particles of 5 to 50 μm and having thermoplastic resin as a main component [F]: Conductive particles having a number average particle size of primary particles in the range of the following formula (1) [(F × 0.12) −3] ≦ P _size ≦ [(F × 0.12) +3] (1)
P _size : number average particle size (μm) of primary particles of conductive particles as constituent element [F]
F: Weight of component [A] in prepreg (g / m ² )
[G] Carbon black in which the number average particle diameter of primary particles is 10 to 50 nm, and the size of a structure in which a plurality of primary particles are combined in the constituent element [B] is 100 to 500 nm.

  The carbon fiber which is the constituent element [A] of the present invention is excellent in specific strength and specific elastic modulus, and has high conductivity, so that it is preferably used for applications requiring excellent mechanical properties and high conductivity. It is done.

  Specific examples of the carbon fiber include acrylic, pitch, and rayon carbon fibers, and acrylic carbon fibers having a particularly high tensile strength are preferably used.

  Such an acrylic carbon fiber can be produced, for example, through the following steps. A spinning dope containing polyacrylonitrile obtained from a monomer containing acrylonitrile as a main component is spun by a wet spinning method, a dry wet spinning method, a dry spinning method, or a melt spinning method. The spun coagulated yarn can be made into a precursor through a spinning process, and then carbon fiber can be obtained through processes such as flame resistance and carbonization.

  As the form of carbon fiber, twisted yarn, untwisted yarn, untwisted yarn, etc. can be used, but in the case of twisted yarn, the orientation of the filaments constituting the carbon fiber bundle is not parallel, so the fiber reinforced composite material obtained Therefore, an untwisted yarn or a non-twisted yarn having a good balance between formability and strength properties of the fiber-reinforced composite material is preferably used.

  The carbon fiber used in the present invention preferably has a tensile modulus in the range of 200 to 440 GPa. The tensile elastic modulus of the carbon fiber is affected by the crystallinity of the graphite structure constituting the carbon fiber, and the elastic modulus increases as the crystallinity increases. Also, the conductivity increases as the crystallinity increases. Therefore, if the elastic modulus is lower than this range, the resulting fiber-reinforced composite material may have insufficient rigidity, resulting in insufficient weight reduction, or the desired conductivity may not be obtained. If it is higher than this range, generally the strength of the carbon fiber tends to decrease. A more preferable elastic modulus is in the range of 230 to 400 GPa, more preferably in the range of 260 to 370 GPa. Here, the tensile elastic modulus of the carbon fiber is a value measured according to JIS R7601-2006.

  The component [B] of the present invention is an epoxy resin having two or more glycidyl groups in one molecule. In the case of an epoxy resin having less than 2 glycidyl groups in one molecule, the glass transition temperature of a cured product obtained by heating and curing a mixture mixed with a curing agent described later is not preferable. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol type epoxy resins such as bisphenol S type epoxy resins, and brominated epoxy resins such as tetrabromobisphenol A diglycidyl ether. , Epoxy resins having a biphenyl skeleton, epoxy resins having a naphthalene skeleton, epoxy resins having a dicyclopentadiene skeleton, novolac epoxy resins such as phenol novolac epoxy resins and cresol novolac epoxy resins, N, N, O-triglycidyl -M-aminophenol, N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-4-amino-3-methylphenol, N, N, N ' N′-tetraglycidyl-4,4′-methylenedianiline, N, N, N ′, N′-tetraglycidyl-2,2′-diethyl-4,4′-methylenedianiline, N, N, N ′ , N′-tetraglycidyl-m-xylylenediamine, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine and other glycidylamine-type epoxy resins, resorcin diglycidyl ether, triglycidyl isocyanurate, etc. be able to. Among these, in the case of aviation, spacecraft applications, etc., it is preferable to include a glycidylamine type epoxy resin from which a cured product having a high glass transition temperature and elastic modulus can be obtained.

  These epoxy resins may be used alone or in combination as appropriate. Mixing an epoxy resin exhibiting fluidity at an arbitrary temperature and an epoxy resin not exhibiting fluidity at an arbitrary temperature is effective in controlling the fluidity of the matrix resin when the resulting prepreg is thermoset. For example, if the fluidity shown before the matrix resin is gelled at the time of thermosetting, the fiber volume content is predetermined due to disturbance in the orientation of the reinforcing fibers or the matrix resin flowing out of the system. As a result, the mechanical properties of the resulting fiber-reinforced composite material may be reduced. Further, combining a plurality of epoxy resins exhibiting various viscoelastic behaviors at an arbitrary temperature is also effective for making the tackiness and draping properties of the obtained prepreg appropriate.

  The prepreg of the present invention has an epoxy compound other than the constituent element [B], for example, a monolith having only one epoxy group per molecule, as long as the heat resistance and mechanical properties are not significantly reduced. An epoxy compound, an alicyclic epoxy resin, etc. can be mix | blended suitably.

  The aromatic amine compound which is the constituent element [C] of the present invention is used as a curing agent for heat-curing the epoxy resin of the constituent element [B]. Examples of the aromatic amine compound include 3,3′-diisopropyl-4,4′-diaminodiphenylmethane, 3,3′-di-t-butyl-4,4′-diaminodiphenylmethane, and 3,3′-diethyl. -5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5 , 5′-dimethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenylmethane, 3,3′-diisopropyl-5,5′-diethyl-4, 4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetra Sopropyl-4,4′-diaminodiphenylmethane, 3,3′-di-t-butyl-5,5′-diisopropyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetra-t- Butyl-4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine Etc. Among these, in the case of aviation, spacecraft applications, etc., 4,4′-diaminodiphenylsulfone and 3,3 ′ are obtained which are excellent in heat resistance and elastic modulus, and can obtain a cured product with a small linear expansion coefficient and a decrease in heat resistance due to moisture absorption. -Diaminodiphenyl sulfone is preferably used. These aromatic amine compounds may be used singly or may be appropriately blended and used. When mixing with other components, either powder or liquid form may be used, and powder and liquid aromatic amine compounds may be mixed and used.

In the present invention, the compounding amount of the aromatic amine compound as the component [C] is such that the active hydrogen in the aromatic amine compound is 0 with respect to one epoxy group of the total epoxy resin constituting the component [B]. The amount is preferably in the range of 7 to 1.3, more preferably 0.8 to 1.2. Here, active hydrogen refers to a highly reactive hydrogen atom bonded to nitrogen, oxygen, or sulfur in an organic compound. When the ratio between the epoxy group and the active hydrogen is out of the predetermined range, the heat resistance and elastic modulus of the obtained cured product may be lowered.

  It is known that the aromatic amine compound which is the constituent element [C] of the present invention generally has a slow crosslinking reaction. Therefore, a curing accelerator can be blended with the component [C] of the present invention in order to accelerate the reaction. Examples of such curing accelerators include tertiary amines, Lewis acid complexes, onium salts, imidazole compounds, urea compounds, and the like. Although the compounding quantity of a hardening accelerator needs to be suitably adjusted with the kind to be used, it is 10 mass parts or less with respect to 100 mass parts of all the epoxy resins, Preferably it is 5 mass parts or less. If the curing accelerator is blended in more than this range, an excessive curing reaction occurs, which may cause a runaway reaction in which the reaction cannot be controlled.

  The thermoplastic resin composed of the polyaryl ether skeleton, which is the constituent element [D] of the present invention, controls the tackiness of the resulting prepreg, controls the fluidity of the matrix resin when the prepreg is heat-cured, and the resulting fiber It is blended to impart toughness without impairing the heat resistance and elastic modulus of the reinforced composite material. Examples of the thermoplastic resin composed of such a polyaryl ether skeleton can include polysulfone, polyphenylsulfone, polyethersulfone, polyetherimide, polyphenylene ether, polyetheretherketone, polyetherethersulfone, and the like. Thermoplastic resins composed of these polyaryl ether skeletons may be used alone or in combination as appropriate. Among these, polyethersulfone can be preferably used because it can impart toughness without deteriorating the heat resistance and mechanical properties of the resulting fiber-reinforced composite material.

  Examples of the terminal functional groups of thermoplastic resins composed of these polyaryl ether skeletons include primary amines, secondary amines, hydroxyl groups, carboxyl groups, thiol groups, acid anhydrides and halogen groups (chlorine, bromine), etc. Can be used. Among these, in the case of a halogen group having a low reactivity with an epoxy resin, a prepreg excellent in storage stability can be obtained. On the other hand, in the case of a functional group excluding a halogen group, it has a reactivity with an epoxy resin. Thus, a prepreg excellent in adhesion between the epoxy resin and the thermoplastic resin can be obtained. In order to suppress degradation of mechanical properties of fiber reinforced composite materials, functional groups excluding halogen groups are preferred. Among them, hydroxyl groups have a relatively low reactivity with epoxy resins, so that degradation of storage stability is also suppressed. it can.

  The blending amount of the thermoplastic resin composed of the polyaryl ether skeleton that is the constituent element [D] of the present invention is preferably in the range of 5 to 40 parts by mass with respect to 100 parts by mass of the constituent element [B]. Preferably it is the range of 10-35 mass parts, More preferably, it is the range of 15-30 mass parts. By setting the blending amount of the thermoplastic resin in such a range, it is possible to balance the viscosity of the mixture, that is, the tackiness of the obtained prepreg and the mechanical properties of the obtained fiber-reinforced composite material.

  The particles mainly composed of the thermoplastic resin, which is the constituent element [E] of the present invention, are blended to add the impact resistance of the fiber reinforced composite material obtained by the present invention. In general, a fiber reinforced composite material has a laminated structure. When an impact is applied to the fiber reinforced composite material, high stress is generated between the layers, and peeling damage occurs. Therefore, when improving the impact resistance against external impacts, a resin layer (hereinafter referred to as an “interlayer resin layer”) formed between layers composed of the component [A] of the fiber reinforced composite material The toughness may be improved. In the present invention, the toughness is improved by blending the component [D] with the epoxy resin which is a matrix resin, and the interlayer resin layer of the fiber reinforced composite material obtained by the present invention is selectively made tougher. Therefore, component [E] is blended.

  The constituent element [E] of the present invention is mainly composed of a thermoplastic resin, and as such a thermoplastic resin, polyamide or polyimide can be preferably used. Among them, impact resistance is greatly improved due to excellent toughness. Of these, polyamides are most preferred. As the polyamide, nylon 12, nylon 11, nylon 6, nylon 6/12 copolymer and the like can be suitably used.

  The component [E] of the present invention can be used only with the above-mentioned thermoplastic resin, but in that case, solvent resistance often becomes a problem. When fiber reinforced composite materials are used as structural members or skins, the surface is often painted, and in aircraft and automotive applications, they may be exposed to hydraulic oil and fuel. The thermoplastic resin constituting the element [E] may swell and deteriorate, thereby reducing the performance.

  As a means for improving the chemical resistance of such a thermoplastic resin, there is a method of blending a small amount of a thermosetting resin. In this case, the linear structure of the thermoplastic resin is taken into the three-dimensional network structure formed by the thermosetting resin, and a semi-IPN structure that is one of the interpenetrating network structures is formed dramatically. Improved solvent resistance.

  The component [E] of the present invention preferably has such a semi-IPN structure, and in order to develop solvent resistance and impact resistance, the thermoplastic resin of the component [E] is a main component. The particles to be processed are particles having a blending ratio (mass%) of the thermoplastic resin and the thermosetting resin in the range of 95: 5 to 70:30, more preferably in the range of 90:10 to 80:20. . Examples of such thermosetting resins include unsaturated polyester resins, vinyl ester resins, epoxy resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimide resins. An epoxy resin of the same type as the constituent element [B], which is the main component of the matrix resin, is preferable because it can be used without a decrease in mechanical properties.

  In order to selectively increase the toughness of the interlayer resin layer of the fiber reinforced composite material obtained in the present invention, it is necessary to keep the component [E] of the present invention in the interlayer resin layer. The number average particle diameter of the constituent element [E] is preferably in the range of 5 to 50 μm, preferably in the range of 7 to 40 μm, more preferably in the range of 10 to 30 μm. By making the number average particle diameter 5 μm or more, the particles of the component [E] remain in the interlayer resin layer of the fiber reinforced composite material obtained without entering the bundle of carbon fibers as the component [A]. By making the number average particle size 50 μm or less, the thickness of the matrix resin layer on the surface of the prepreg is optimized, and in the resulting fiber-reinforced composite material, the volume content of the carbon fiber as the component [A] is appropriate. Can be Here, the number average particle diameter is observed by enlarging the constituent element [E] 200 times or more with a laser microscope (ultra-deep color 3D shape measurement microscope VK-9510: manufactured by Keyence Co., Ltd.). For 50 or more particles, the average value is used after measuring the diameter of the circumscribed circle of the particles as the particle size.

  The shape of the particle mainly composed of the plastic resin which is the constituent element [E] of the present invention may be amorphous, spherical, porous, needle-like, whisker-like and flake-like. Since it does not deteriorate the flow characteristics, it has excellent carbon fiber impregnation properties, and the delamination caused by local impact is further reduced at the time of falling weight impact on the fiber reinforced composite material. When stress is applied to the material, since there are fewer delamination parts caused by the local impact that is the starting point of fracture due to stress concentration, a fiber-reinforced composite material that exhibits high impact resistance is obtained. Therefore, it is preferable.

  The blending amount of the particles mainly composed of the plastic resin, which is the constituent element [E] of the present invention, is preferably in the range of 5 to 40 parts by weight, more preferably 10 to 100 parts by weight of the constituent element [B]. It is the range of -35 mass parts, More preferably, it is the range of 15-30 mass parts. By setting the blending amount of the thermoplastic resin in such a range, it is possible to balance the viscosity of the mixture, that is, the tackiness of the obtained prepreg and the mechanical properties of the obtained fiber-reinforced composite material.

  The components [F] and [G] of the present invention are blended in order to increase the conductivity of the fiber-reinforced composite material obtained by the present invention.

  As described above, the fiber-reinforced composite material obtained by the present invention is selectively toughened by disposing the constituent element [E] in the interlayer resin layer, and the impact resistance is improved. However, such a fiber reinforced composite material gives a high impact resistance to the fiber reinforced composite material, while forming a resin layer serving as an insulating layer between the layers. Has the disadvantage that it is significantly reduced.

  Therefore, in order to increase the conductivity of the interlayer resin layer of the fiber reinforced composite material, the conductive particles which are the constituent element [F] of the present invention are blended. Such conductive particles may be particles that behave as electrically good conductors, and are not limited to those composed only of conductors. Preferably, the particles have a volume resistivity of 15 Ωcm or less, more preferably 10 Ωcm, and even more preferably 5 Ωcm. By setting the volume specific resistance in such a range, a conductive path can be formed in the interlayer resin layer to increase conductivity. Here, the volume resistivity was calculated from the measured value by setting the sample in a cylindrical cell having four probe electrodes, measuring the thickness and resistance value of the sample with a pressure of 60 MPa applied to the sample. Value. Examples of such conductive particles include metal particles, polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaphthene particles, polyethylene dioxythiophene particles and other conductive polymer particles, carbon particles, and inorganic materials. Particles in which nuclei are coated with a conductive substance and particles in which nuclei of organic materials are coated with a conductive substance can be used. Among these, carbon particles, particles in which the core of an inorganic material is coated with a conductive material, and particles in which the core of an organic material is coated with a conductive material are preferably used because of high conductivity and stability. In particular, carbon particles are particularly preferably used because they can be obtained at low cost.

  In the case of particles in which the core of the inorganic material is coated with a conductive substance, examples of the inorganic material that is the core include inorganic oxides, inorganic-organic composites, and carbon.

  Examples of inorganic oxides include single inorganic oxides such as silica, alumina, zirconia, titania, silica / alumina, silica / zirconia, and two or more composite inorganic oxides.

  Examples of the inorganic organic composite include polyorganosiloxane obtained by hydrolyzing metal alkoxide and / or metal alkyl alkoxide.

  As carbon, crystalline carbon and amorphous carbon are preferably used. As the amorphous carbon, for example, “Bellpearl (registered trademark)” C-600, C-800, C-2000 (manufactured by Air Water Co., Ltd.), “NICABEADS (registered trademark)” ICB, PC, MC ( Nippon Carbon Co., Ltd.), Glassy Carbon (Tokai Carbon Co., Ltd.), High Purity Artificial Graphite SG Series, SGB Series, SN Series (SEC Carbon Co., Ltd.), True Spherical Carbon (Gunei Chemical Industry Co., Ltd.) ))) And the like.

In the case of particles in which the core of the organic material is coated with a conductive substance, the organic material as the core includes unsaturated polyester resin, vinyl ester resin, epoxy resin, benzoxazine resin, phenol resin, urea resin, melamine resin Thermosetting resins such as polyimide resins, polyamide resins, phenol resins, amino resins, acrylic resins, ethylene-vinyl acetate resins, polyester resins, urea resins, melamine resins, alkyd resins, polyimide resins, urethane resins, and divinylbenzene Examples thereof include thermoplastic resins such as resins, and these organic materials may be used alone or in combination of two or more. Among these, acrylic resins and divinylbenzene resins having excellent heat resistance, and polyamide resins having excellent impact resistance are preferably used.

  The conductive particles as the constituent element [F] of the present invention must be localized in the interlayer resin layer in order to increase the conductivity of the interlayer resin layer of the fiber-reinforced composite material obtained in the present invention. In the fiber reinforced composite material, the conductive path is not formed unless the constituent particles [A] and the conductive particles [F] located in the upper and lower portions of the interlayer resin layer are in contact with each other. Less. Therefore, it is necessary to adjust the number average particle diameter of the conductive particles as the constituent element [F] of the present invention to an arbitrary range.

  However, in general, in order to use a fiber reinforced composite material as a member of an aircraft or an automobile, the basis weight (mass per unit area) of the carbon fiber, which is the constituent element [A] in the prepreg, depends on the purpose. It is necessary to adjust the weight per unit area. When the basis weight of the carbon fiber is changed, the thickness of the interlayer resin layer varies in order to keep the volume content of the carbon fiber in the obtained fiber-reinforced composite material constant. Therefore, in the component [F] of the present invention, The number average particle diameter of certain conductive particles needs to be changed according to the basis weight of the carbon fiber which is the constituent element [A] in the prepreg. Therefore, in this invention, it is good to adjust the number average particle diameter of the electroconductive particle which is a component [F] to the range of following Formula (1).

[(F × 0.12) −3] ≦ P _size ≦ [(F × 0.12) +3] (1)
P _size : number average particle size (μm) of primary particles of conductive particles as constituent element [F]
F: The basis weight (g / m ² ) of the component [A] in the prepreg.

  By setting the number average particle diameter of the component [F] within the range of the formula (1), a conductive path can be appropriately formed according to the basis weight of the carbon fiber as the component [A] in the prepreg, The volume content of the carbon fibers in the obtained fiber-reinforced composite material can be set within a predetermined range. Here, the number average particle diameter is observed by enlarging the constituent element [E] 200 times or more with a laser microscope (ultra-deep color 3D shape measurement microscope VK-9510: manufactured by Keyence Co., Ltd.). For 50 or more particles, the average value is used after measuring the diameter of the circumscribed circle of the particles as the particle size.

  The compounding quantity of the electroconductive particle which is the component [F] of this invention is the range of 0.5-10 mass parts with respect to 100 mass parts of component [B], More preferably, it is 1-8 mass parts. It is a range, More preferably, it is the range of 2-5 mass parts. It is possible to balance the electrical conductivity and mechanical properties of the fiber-reinforced composite material obtained by setting the blending amount of the conductive particles in such a range.

  The fiber-reinforced composite material obtained by the present invention has the conductivity of the interlayer resin layer that was an insulating layer by disposing the conductive particles as the constituent element [F] in the interlayer resin layer of the fiber-reinforced composite material as described above. To improve the electrical conductivity in the thickness direction of the fiber-reinforced composite material. However, if the contact between a part of the conductive particles of the component [F] and the carbon fiber bundles located above and below the interlayer resin layer is insufficient, a conductive path is not formed, and the conductivity improvement effect is obtained. There is a possibility of fading. In addition, even within the bundle composed of the component [A], if there is little contact between the components [A], it is difficult to conduct electricity, which may reduce the conductivity.

  Therefore, in order to solve such a problem, carbon black which is the constituent element [G] of the present invention is blended. Carbon black is carbon-based fine particles produced by controlling the number average particle size of primary particles in general to be 3 to 500 nm. Examples of such carbon black include furnace black, hollow furnace black, ketjen black, acetylene black, and channel black.

  When carbon black is dispersed in the constituent element [B], it usually forms a structure in which a plurality of primary particles are connected, and carbon black that easily forms a large structure is considered to have excellent conductivity. However, if the size of the structure is too large, it will enter between the bundles of the component [A] or between the bundle of the component [A] causing the poor contact and the conductive particles of the component [F]. Can not be. For the reasons described above, the size of the structure of the carbon black which is the constituent element [G] of the present invention may be in the range of 100 to 500 nm in terms of number average particle diameter, preferably in the range of 120 to 400 nm. Preferably it is the range of 130-300 nm. By setting the size of the carbon black structure within such a range, the bundle of the constituent elements [A] and the constituent elements [A] and the conductive particles as the constituent elements [F] are connected to form a conductive path. As a result, the conductivity in the thickness direction of the resulting fiber-reinforced composite material can be dramatically improved. Here, the value obtained by the following method is used for the size of the structure of carbon black. That is, after the constituent element [G] is dispersed in the constituent element [B], the curing agent which is the constituent element [C] is blended and poured into a predetermined mold, and is heated from room temperature to 180 ° C. in a hot air oven. The temperature was raised by 1.5 ° C. per minute up to a temperature of 1 mm, and then kept at a temperature of 180 ° C. for 2 hours to obtain a 2 mm thick resin cured plate. The obtained hardened plate is processed with a microtome and observed with a transmission electron microscope (TEM), and the distance of the longest part is measured as the particle diameter for 50 or more arbitrary structures, and the average value is obtained. It is.

  In order to control the size of the carbon black structure, it is necessary to control the number average particle size of the primary particles of carbon black. If the number average particle size of the primary particles is too small, the cohesive force becomes too strong, the dispersibility is lowered, and the size of the structure is increased. On the other hand, if the number average particle size of the primary particles is too large, the cohesive force is lowered and the structure tends not to be formed. From the above, the number average particle size of the primary particles of carbon black is preferably in the range of 10 to 50 nm, preferably in the range of 15 to 40 nm, and more preferably in the range of 20 to 30 nm. By setting the number average particle size of the primary particles of carbon black in such a range, the size of the structure can be adjusted. Here, the number average particle diameter of the primary particles of carbon black is the observation of the carbon black with a field emission scanning electron microscope (FE-SEM), and for 100 arbitrary particles, the number of circles circumscribing the particles. After measuring the diameter as the particle diameter, an average value is used.

  The blending amount of carbon black which is the constituent element [G] of the present invention is preferably in the range of 1 to 5 parts by mass, more preferably in the range of 1 to 4 parts by mass with respect to 100 parts by mass of the constituent element [B]. More preferably, it is the range of 2-3 mass parts. It is possible to balance the electrical conductivity and mechanical properties of the fiber-reinforced composite material obtained by setting the blending amount of carbon black in such a range.

  The prepreg of the present invention can be produced by various known methods. For example, the matrix resin is dissolved in an organic solvent selected from acetone, methyl ethyl ketone, methanol, and the like to lower the viscosity, and the wet method in which the reinforcing fiber is impregnated, or the matrix resin is heated to lower the viscosity without using the organic solvent, A prepreg can be produced by a method such as a hot melt method for impregnating reinforcing fibers.

  In the wet method, the reinforced fiber is pulled up after being immersed in a liquid containing a matrix resin, and an organic solvent is evaporated using an oven or the like to obtain a prepreg.

  In the hot melt method, a matrix resin whose viscosity has been reduced by heating is impregnated directly into a reinforcing fiber, or a release paper sheet with a resin film once coated with a matrix resin on a release paper (hereinafter referred to as “resin”). The film may be referred to as “film” first), then a resin film is laminated on the reinforcing fiber side from both sides or one side of the reinforcing fiber, and the reinforcing fiber is impregnated with the matrix resin by heating and pressing. .

  The method for producing the prepreg of the present invention is preferably a hot melt method in which the reinforcing fibers are impregnated with a matrix resin without using an organic solvent, since substantially no organic solvent remains in the prepreg.

  Specific examples of the method for producing the prepreg of the present invention by the hot melt method include the following methods, but any method can be used. That is, in the first method, the epoxy resin composition is formed in a single step by heating and pressurizing the resin film comprising the constituent elements [B] to [G] of the present invention from both sides or one side of the constituent element [A]. This is a so-called one-stage impregnation hot melt method for impregnation. The second method is a multistage impregnation hot melt method in which the epoxy resin composition is divided into multiple stages and impregnated by heating and pressing from both sides or one side of the component [A]. In the multistage impregnation hot melt method, the number of times the matrix resin is impregnated into the constituent element [A] is not limited, but the manufacturing cost increases as the number of times increases. Therefore, a so-called two-stage impregnation hot melt method in which the epoxy resin composition is impregnated by heating and pressurizing from both sides or one side of the component [A] in two stages is preferably used. Among the two-stage impregnation hot melt methods, first, the resin film 1 consisting of the constituent elements [B], [C], [D] and [G] and substantially free of the constituent elements [E] and [F], After impregnating the component [A] from both sides or one side to obtain a prepreg precursor, the resin film 2 composed of the components [B] to [G] and including the components [E] and [F] is used as the prepreg precursor. A method of obtaining a prepreg by sticking to both sides or one side of the body is preferably used.

  When the one-stage impregnation hot melt method is used, in the process of impregnating the component [A] with the resin film composed of the components [B] to [G] of the present invention, the component [A] is converted into the component [E]. ] And [F] are selectively disposed on the surface of the prepreg by blocking the entry of the particles of [F] and [F]. However, it is difficult to block all the particles of the constituent elements [E] and [F] with the constituent element [A], and a part of the constituent element [D] enters the layer composed of the constituent element [A]. Sometimes.

  On the other hand, when the two-stage impregnation hot melt method is used, first, the component [A] is impregnated with the prepreg precursor obtained by impregnating the component [A] with the resin film 1 not containing the components [E] and [F]. By applying the resin film 2 containing E] and [F], the particles of the constituent elements [E] and [F] can be selectively arranged on the prepreg surface. Therefore, in the prepreg obtained by the two-stage impregnation hot melt method, the amount of the constituent elements [E] and [F] existing in the range corresponding to the average thickness of 15% of the prepreg measured by the method described later increases. In the prepreg of the present invention, the particles of the constituent elements [E] and [F] are selectively disposed in a range corresponding to an average thickness of 15% of the prepreg from the surface of the prepreg, thereby achieving high impact resistance. And a fiber-reinforced composite material having both conductivity and electrical conductivity. The two-stage impregnation hot melt method is preferable because particles of many constituent elements [E] and [F] can be arranged on the prepreg surface.

  The matrix resin (hereinafter referred to as an epoxy resin composition) composed of the constituent elements [B] to [G] used in the present invention can be produced by various known methods. For example, the method of kneading each component with a kneader is mentioned. Moreover, you may knead | mix each component using a biaxial extruder.

  When the prepreg of the present invention is produced by the above-described two-stage impregnation hot melt method, the constituent elements [B], [C], [D] and [G] to be impregnated into the constituent element [A] in the first stage A component [B] that is affixed to both sides or one side of a primary resin substantially free of components [E] and [F] and a prepreg precursor impregnated with the primary resin in the component [A]. To [G], and a secondary resin substantially including the constituent elements [E] and [F] is required.

  When producing such a primary resin with a kneader, for example, first, the constituent elements [B] and [D] are heated and mixed at a temperature in the range of 130 to 160 ° C. Here, it is preferable to dissolve until the solid of the component [D] does not exist. Next, after cooling to a temperature of 50 ° C. or lower, the component [G] is dispersed. Here, the carbon black as the constituent element [G] often forms an aggregate, and when all the components are kneaded at once, it may cause poor dispersion. As described above, the size of the structure formed by carbon black is between the bundle of the component [A] or the bundle of the component [A] causing the poor contact and the component [F] if it is too large. Since it becomes impossible to enter the gaps between the conductive particles, the thickness is preferably in the range of 100 to 500 nm, preferably in the range of 120 to 400 nm, and more preferably in the range of 130 to 300 nm. As a method for adjusting the carbon black, which is the constituent element [G], to such a particle size range, a master batch can be manufactured and used in advance with a part of the constituent element [B] and the constituent element [G]. . The compounding ratio of the master batch composed of a part of the component [B] and the component [G] is preferably 5 to 50 parts by mass of the component [G] with respect to 100 parts by mass of the component [B]. More preferably, it is the range of 10-30 mass parts. If the blending amount of the carbon black is larger than this range, the dispersibility of the carbon black may be deteriorated. Further, if the blending amount of the carbon black is smaller than this range, a sufficient amount of carbon black cannot be blended, so that the conductivity may be impaired.

  Examples of the method for producing a masterbatch composed of a part of the constituent element [B] and the constituent element [G] include the following kneading methods. A kneading method comprising a step of mixing a part of the component [B] and the component [G], and a step of kneading the mixture obtained in the melting step with an open type roll mill.

  In such a kneading method, the step of mixing a part of the component [B] and the component [G] includes a twin screw extruder, a single screw extruder, and a heatable twin or single screw. This can be done by means selected from the group consisting of feeders. Moreover, as a roll mill, 1 type chosen from the group which consists of a continuous type 2 roll mill, a continuous type 3 roll mill, and a batch type roll mill can be used. Among these, a three-roll mill is preferable from the viewpoint of kneading ability. Moreover, in order to improve the dispersibility of the component [G] in the master batch, it is preferable to knead the master batch multiple times with a three-roll mill.

The surface resistivity of the master batch composed of a part of the component [B] of the present invention and the component [G] is preferably 1 × 10 ⁶ Ω or less, more preferably 1 × 10 ⁴ Ω or less, More preferably, it is 5 × 10 ³ Ω or less. When the surface resistivity of the master batch composed of a part of the component [B] and the component [G] is larger than this range, the conductivity in the thickness direction of the obtained fiber-reinforced composite material may be deteriorated.

  Here, the surface resistivity of the master batch composed of a part of the component [B] and the component [G] can be measured by the following method. A masterbatch composed of a part of the component [B] and the component [G] and 4,4′-diaminodiphenylsulfone are mixed with 4,4′-diaminodiphenylsulfone for one epoxy group contained in the masterbatch. After mixing so that active hydrogen may be 0.35-0.5, and coating to a glass plate so that thickness may be set to 75 micrometers, it hold | maintains at 180 degreeC temperature for 2 hours with a hot air oven, and obtains a resin hardening board. The surface resistivity of this cured resin plate is measured at an applied voltage of 1000 V using Hirestar UP MCP-HT450 (manufactured by Mitsubishi Chemical Analytech). Alternatively, the surface resistivity of the cured resin plate produced in the same manner is measured at an applied voltage of 10 V using a Lorester GP MCP-T600 (manufactured by Mitsubishi Chemical Analytech).

Since the obtained primary resin is impregnated into the constituent element [A], the viscosity characteristic is important. When the viscosity of the obtained primary resin is too low, a large amount of resin flow occurs during molding, and the amount of resin decreases, so that the mechanical properties may be lowered. Moreover, when the viscosity of the obtained primary resin is too high, when the film formation process of the epoxy resin composition in the hot melt method occurs, the unimpregnated part is generated in the impregnation process of the reinforcing fibers. There is. In order not to cause these problems, the viscosity characteristics of the primary resin must satisfy the following condition (I). That is,
Condition (I): a component in which the ratio of the number of epoxy groups in component [B] and the number of active hydrogens in component [C] is 1: 1 (0.7 ≦ l ≦ 1.3) [ C], component [D] in an amount of m parts by mass (5 ≦ m ≦ 40) with respect to 100 parts by mass of component [B], and n parts by mass with respect to 100 parts by mass of component [B] ( The viscosity at 70 ° C. of the resin composition consisting of the constituent elements [B], [C], [D] and [G] containing the constituent element [G] in the blending amount of 1 ≦ n ≦ 5) is 10 to 10. The presence of l, m, and n is 500 Pa · s.

  Here, the viscosity at a temperature of 70 ° C. is obtained by using a dynamic viscoelastic device ARES-2KFRTN1-FCO-STD (manufactured by TA Instruments Inc.) and a flat parallel plate having a diameter of 40 mm on the upper and lower measurement jigs. After setting the epoxy resin composition so that the distance between the upper and lower jigs is 1 mm, the measurement temperature range is 40 to 140 ° C. in the torsion mode (measurement frequency: 0.5 Hz). Measured at ° C / min.

  As a method for setting the viscosity of the primary resin at a temperature of 70 ° C. within the range of the condition (I), a solid epoxy resin that does not exhibit fluidity at a temperature of 25 ° C. included in the component [B], and a component [ D] within a proper range of the amount of the thermoplastic resin composed of the polyaryl ether skeleton, and within the proper range of the size of the carbon black structure as the constituent element [G] in the resin composition It is to do. In particular, the blending amount of the component [D] and the size of the component [G] structure have a great influence on the viscosity. Therefore, as described above, the blending amount of the component [D] is preferably in the range of 5 to 40 parts by mass, more preferably in the range of 10 to 35 parts by mass, with respect to 100 parts by mass of the component [B]. More preferably, it is blended in the range of 15 to 30 parts by mass, and in the component [B], the size of the structure of the component [G] may be in the range of 100 to 500 nm, preferably 120 to 400 nm. More preferably, the range is 130 to 300 nm.

  In the case of producing such a secondary resin with a kneader, as in the case of the primary resin, the constituent elements [B] and [D] are heated and mixed at a temperature in the range of 130 to 160 ° C. D] is dissolved and then cooled to a temperature of 50 ° C. or lower, and a masterbatch prepared in advance using a part of the component [B] and the component [G], the components [E] and [E] F] is added and dispersed, and finally the aromatic amine compound as the constituent element [C] is added and kneaded. The preferred embodiment of such a masterbatch is the same as that for the primary resin.

The obtained secondary resin was affixed to both sides or one side of the prepreg precursor, and since there was no impregnation of the component [A], the viscosity characteristics were not as important as the primary resin, but the viscosity was low. The tackiness of the prepreg becomes strong. On the other hand, when the viscosity is high, the tackiness is lowered, and the handling property of the prepreg is lowered. Therefore, it is preferable that the viscosity characteristics of the secondary resin satisfy the following condition (II). That is,
Condition (II): a component in which the ratio of the number of epoxy groups in component [B] and the number of active hydrogens in component [C] is 1: 1 (0.7 ≦ l ≦ 1.3) [ C], component [B] component [D] in an amount of m parts by mass (5 ≦ m ≦ 40) with respect to 100 parts by mass, and component [B] x parts by mass (10 ≦ x ≦ 40) component [E], component [B] component [F] and component [F] and component [F] of component y [0.5 ≦ y ≦ 10] with respect to 100 parts by mass of component [B] [B] Temperature of 70 ° C. of resin composition comprising constituent elements [B] to [G] including constituent element [G] in an amount of n parts by mass (1 ≦ n ≦ 5) per 100 parts by mass The presence of l, m, n, x, and y is such that the viscosity at 100 to 500 Pa · s.

  The viscosity at a temperature of 70 ° C. is the same as that described above, using a dynamic viscoelastic device ARES-2KFRTN1-FCO-STD (manufactured by TA Instruments Inc.), a flat plate having a diameter of 40 mm on the upper and lower measurement jigs. Using a parallel plate, set the epoxy resin composition so that the distance between the upper and lower jigs is 1 mm, then increase the measurement temperature range from 40 to 140 ° C in the torsion mode (measurement frequency: 0.5 Hz) It is a value measured at 1.5 ° C./min.

If the blending ratio of each component in the obtained primary and secondary resins is in an uncured state, infrared absorption analysis (abbreviation: IR), hydrogen-nuclear magnetic resonance (abbreviation: ¹ H-NMR), carbon It can be identified by combining analytical methods such as -13 nuclear magnetic resonance (abbreviation: ¹³ C-NMR), gas chromatography-mass spectrometry (abbreviation: GC-MS), and high performance liquid chromatography (abbreviation: HPLC). For example, the epoxy resin composition was dissolved in water, alcohols, acetonitrile, dichloromethane, trifluoroacetic acid or the like alone or in a mixed solvent, then impurities were filtered, and the supernatant was measured by HPLC and separated by filtration. A method of measuring a thing by IR can be used. Moreover, the component mix | blended with the resin composition by the said method can be identified, and the epoxy equivalent of the mix | blended epoxy resin component can also be calculated from information, such as the obtained molecular weight and the number of epoxy groups. it can.

  In the prepreg of the present invention, the range corresponding to the average thickness of 13% of the prepreg from the surface of the obtained prepreg is composed of constituent elements [B] to [G]. That is, the component [A] is not included in a range corresponding to an average thickness of 13% from the surface of the prepreg. By setting it as the prepreg of such a structure, an interlayer resin layer can be formed in the fiber reinforced composite material obtained. Here, the thickness of the matrix resin layer on the prepreg surface can be evaluated by the following method. That is, the prepreg obtained in the present invention is closely attached between two smooth support plates, and is cured by gradually raising the temperature over a long period of time. What is important at this time is to make the gel as low as possible. If the temperature is raised before gelation, the resin in the prepreg will flow, and the exact thickness of the matrix resin layer cannot be evaluated, so after gelation, the temperature is gradually increased over time to cure the prepreg, A fiber reinforced composite material is used. A cross section of the obtained fiber reinforced composite material is polished, and magnified to 200 times or more with an epi-illumination type optical microscope to take a picture. Using this cross-sectional photograph, first, the average thickness of the prepreg is determined. The average thickness of the prepreg is measured at at least five points arbitrarily selected on the photograph, and the average is taken. Next, the thickness of the matrix resin layer formed on the surface of the fiber reinforced composite material is obtained. The thickness of the matrix resin layer is also measured at at least five points arbitrarily selected on the photograph, and the average is taken. The ratio can be calculated from the average thickness of the obtained prepreg and the average thickness of the matrix resin layer.

  In the prepreg of the present invention, it is preferable that 85% by mass or more of each of the constituent elements [E] and [F] is present in a range corresponding to an average thickness of 15% of the prepreg from the surface of the obtained prepreg. That is, the constituent elements [E] and [F] are preferably localized on the surface of the prepreg. By using a prepreg having such a structure, it becomes possible to form an interlayer resin layer in which the constituent elements [E] and [F] are selectively arranged in the obtained fiber-reinforced composite material, and a high impact resistance. A fiber reinforced composite material having conductivity can be obtained. The degree of localization of particles in the prepreg can be evaluated by the following method. That is, after obtaining the fiber reinforced composite material by the above-described method, the cross section is polished, and the photograph is magnified to 200 times magnification or more with an epi-illumination optical microscope. Using this cross-sectional photograph, first, the average thickness of the prepreg is determined. The average thickness of the prepreg is measured at at least five points arbitrarily selected on the photograph, and the average is taken. Next, a line is drawn in parallel with the outermost surface of the prepreg at a position of 15% of the thickness of the prepreg from the surface that is in contact with both support plates. The total cross-sectional area of each particle existing between the surface in contact with the support plate and 15% parallel lines is quantified on both sides of the prepreg. Further, the total sum of the cross-sectional areas of the respective constituent elements [E] and [F] existing over the total thickness of the prepreg is also quantified. The ratio of the total cross-sectional area of each particle existing in a range corresponding to 15% of the average thickness of the prepreg from the surface of the prepreg to the total cross-sectional area of the particles existing over the total thickness of the prepreg is determined from the average thickness of the prepreg from the prepreg surface. The amount of particles existing within 15%. The quantification of the particle cross-sectional area may be performed by an image analyzer or by cutting out all the particle portions existing in a predetermined region from a cross-sectional photograph and weighing the weight. In order to eliminate the influence of variation in the partial distribution of particles, this evaluation is performed over the entire width of the obtained photo, and the same evaluation is performed for five or more arbitrarily selected photos, and the average is obtained. It is necessary to take When it is difficult to distinguish between the particles and the matrix resin, one of them is selectively stained and observed. The microscope may be an optical microscope or a scanning electron microscope, and may be properly used depending on the size of the particles and the staining method. In the present invention, the ratio calculated by the area ratio as described above is defined as the mass ratio of fine particles existing in a range corresponding to an average thickness of 15% of the prepreg from the surface of the prepreg.

  The cross-sectional observation of the obtained fiber reinforced composite material is magnified to 200 times or more with an epi-illumination type optical microscope, a photograph is taken, and the diameter of each particle of the constituent elements [E] and [F] is measured. Thus, the number average particle sizes of the constituent elements [E] and [F] can be obtained. Specifically, after measuring the particle diameter of 100 arbitrary particles for each of the constituent elements [E] and [F], the number average particle diameter is used as an average value.

  The preferable range of the number average particle diameter of the constituent elements [E] and [F] is the same as the above-described preferable range of the number average particle diameter.

  The obtained fiber reinforced composite material is processed into a thin piece with a microtome or a focused ion beam (FIB) apparatus, and observed with a transmission electron microscope (TEM) to determine the diameter of the primary particle of the constituent element [G]. By measuring, the number average particle diameter of the constituent element [G] can be obtained. Specifically, after measuring the particle size of 50 or more primary particles of the constituent element [G], an average value can be used as the number average particle size.

  The preferable range of the number average particle diameter of the primary particles of the constituent element [G] obtained here is the same as the number average particle diameter described above.

  Further, in the prepreg of the present invention, the volume content (hereinafter referred to as Vf) of the carbon fiber which is the constituent element [A] is preferably in the range of 50 to 65% by volume, more preferably 53 to 62% by volume. More preferably, it is the range of 55-60 volume%. A fiber-reinforced composite material that prevents an increase in the weight of the fiber-reinforced composite material obtained by setting Vf in such a range and suppresses the occurrence of defects such as unimpregnated portions and voids inside the fiber-reinforced composite material and has excellent mechanical properties. Can be obtained. Here, Vf of the prepreg is a value obtained by the following method, that is, a 100 × 100 mm test piece is cut out from the prepreg obtained in the present invention, and the volume is calculated by measuring the thickness with a micrometer. Then, according to the test method of “prepreg mass per unit area, carbon fiber mass per unit area, resin mass content and fiber mass content” described in JIS K7071 (1988), the carbon fiber mass per unit area is measured, and carbon The value calculated by calculating the volume using the density provided by the fiber manufacturer and dividing by the volume of the test piece is used.

  The fiber-reinforced composite material of the present invention can be obtained by curing the prepreg of the present invention. When forming a fiber reinforced composite material using a prepreg, various known methods can be used. For example, a method in which the obtained prepreg is cut into a predetermined size and then singly or a predetermined number of prepregs are laminated and then heat-cured while applying pressure can be preferably used.

  There are a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, and the like as methods for heating and curing while applying pressure to the prepreg laminate, and they are properly used depending on the intended use. Among these, in the case of aircraft and spacecraft applications, a fiber-reinforced composite material having excellent performance and stable quality can be obtained, and therefore, an autoclave molding method is often applied.

  The temperature at which the fiber-reinforced composite material is molded needs to be appropriately adjusted depending on the type of the curing agent contained in the epoxy resin composition. In the present invention, the aromatic amine as the constituent element [C] is used as the curing agent. Since the compound is used, molding is usually performed at a temperature in the range of 150 to 220 ° C. If the molding temperature is too low, sufficient rapid curability may not be obtained. Conversely, if the molding temperature is too high, warping due to thermal strain may be likely to occur.

  The pressure at which the fiber-reinforced composite material is molded by the autoclave molding method varies depending on the thickness of the prepreg, the volume content of the carbon fiber, etc., but is usually in the range of 0.1 to 1 MPa. By setting the molding pressure within such a range, a fiber-reinforced composite material free from defects such as voids and free from dimensional variations such as warpage can be obtained in the obtained fiber-reinforced composite material.

  The fiber-reinforced composite material obtained by the present invention comprises particles mainly composed of a thermoplastic resin as a constituent element [E], conductive particles as a constituent element [F], and carbon black as a constituent element [G]. It is blended as described above and is characterized by high impact resistance and conductivity.

  Such impact resistance can be measured by post-impact compressive strength (hereinafter referred to as CAI). The CAI of the fiber-reinforced composite material of the present invention is about 1 mm in thickness of the test piece according to JIS K 7089 (1996). The CAI after applying an impact energy of 6.7 J is preferably 280 MPa or more, more preferably 300 MPa or more, and further preferably 310 MPa or more. If the CAI is lower than this range, the strength may be insufficient, and in particular, it cannot be used for structural members such as aircraft. There is no restriction | limiting in particular about the upper limit of CAI, The safety | security when a fiber reinforced composite material is applied as a structural member is so high that a numerical value is high.

  Such conductivity can be measured by the following method. That is, the unidirectional prepreg obtained in the present invention is symmetrically laminated with the carbon fiber longitudinal direction being set to 0 °, and repeated twice based on [+ 45 ° / 0 ° / −45 ° / 90 °], Cut out from the fiber reinforced composite panel obtained by heating and pressurizing in an autoclave in a size of 50 mm long × 50 mm wide, completely remove the resin layers on both surfaces by polishing, and then apply conductive paste on both sides. Sample pieces. This is a method in which the volume specific resistance obtained by measuring the resistance in the stacking direction of the obtained sample piece by using the R6581 digital multimeter manufactured by Advantest Co., Ltd. by the four-terminal method is made conductive in the thickness direction. Examples of the conductive paste include “Dotite (registered trademark)” D-550, FN-101, D-500, D-362, XA-9015, FE-107, XC-12, XC-32, and SH-. 3A, XA-436, FA-545, XA-824, FC-403R, XC-223, FA-501, FA-333, FA-353N, XA-602N, XA-472, FC-415, XB-101G, SN-8800G, XB-114, XB-107, XB-110, FH-889, FEL-190, FEL-615, FEC-198, FEA-685, XB-101G (manufactured by Fujikura Kasei Co., Ltd.); N- 2057, N-2057A (manufactured by Shoei Chemical Industry Co., Ltd.); CA-6178, CA-6178B, CA-6178T, CA-2500E, CA-BE04 ( SP, SD, ST, SF, SL, SI, NPS-J, NPS, NPS-J-HTB, NPS-HTB, NPG-J (manufactured by Harima Kasei Co., Ltd.); MDot (registered trademark) "-SLP," CUX (registered trademark) "-R series (manufactured by Mitsuboshi Belting Co., Ltd.) and the like can be used. The volume resistivity which is an index of conductivity in the thickness direction of the fiber reinforced composite material of the present invention is preferably 10 Ωcm or less, more preferably 7 Ωcm or less, and further preferably 5 Ωcm or less. By making the volume resistivity below this range, it is possible to suppress electrical damage such as lightning strikes and static electricity dissipation when using fiber reinforced composite materials as members, especially in aircraft applications, as a measure against lightning strikes. Since the metal mesh etc. provided on the member surface can be reduced, it is also effective in reducing the weight. Here, the thickness direction of the fiber reinforced composite material means a direction in which the prepreg of the present invention used for the production is laminated.

  The fiber reinforced composite material obtained from the prepreg of the present invention is excellent in strength, rigidity, impact resistance, conductivity, etc., so primary structural members such as aircraft fuselage, main wing, tail wing and floor beam, flap, aileron, Secondary structural members such as cowls, fairings and interior materials, rocket motor cases and satellite structural materials, such as structural materials for mobile and aerospace applications, automobiles, ships and rail vehicles, building materials, windmill blades, It can be suitably used for a wide range of uses such as computer applications such as IC trays and notebook PC housings (housings).

  Hereinafter, the prepreg and carbon fiber composite material of the present invention will be described more specifically with reference to examples. The unit “part” of the composition ratio means part by mass unless otherwise specified. Various characteristics (physical properties) were measured in an environment of a temperature of 23 ° C. and a relative humidity of 50% unless otherwise specified.

<Materials used in Examples>
(1) Constituent element [A]: Carbon fiber “Treka (registered trademark)” T800S-24K-10E (24,000 fibers, fineness: 1,033 tex, tensile elastic modulus: 294 GPa, density 1.8 g / cm ³ , Toray Industries, Inc.).

(2) Component [B]: Epoxy resin having two or more glycidyl groups in one molecule “Araldite (registered trademark)” MY721 (component: tetraglycidyldiaminodiphenylmethane, manufactured by Huntsman Japan)
"Araldite (registered trademark)" GY282 (component: bisphenol F type epoxy resin, manufactured by Huntsman Japan)
GAN (component: N, N-diglycidyl aniline, manufactured by Nippon Kayaku Co., Ltd.).

(3) Component [C]: Aromatic amine compound “Seikacure (registered trademark)” S (4,4′-diaminodiphenylsulfone, manufactured by Seika Corporation).

(4) Component [D]: Thermoplastic resin composed of polyaryl ether skeleton “VIRANTAGE (registered trademark)” VW-10700RFP (component: terminal hydroxyl group polyethersulfone, manufactured by Solvay Specialty Polymers).

(5) Component [E]: Particles mainly composed of thermoplastic resin / nylon 12 particles SP-10 (component: nylon 12, number average particle size: 10 μm, shape: spherical, manufactured by Toray Industries, Inc.)
-Epoxy-modified nylon particles A (number average particle size: 13 μm) obtained by the following production method
90 parts of transparent polyamide ("Grillamide (registered trademark)" TR55, manufactured by Ms Chemie Japan), 7.5 parts of epoxy resin ("jER (registered trademark)" 828, manufactured by Mitsubishi Chemical Corporation) and curing agent 2.5 parts ("Tomide (registered trademark)"# 296, manufactured by T & K Toka) were added to a mixed solvent of 300 parts of chloroform and 100 parts of methanol to obtain a homogeneous solution. Next, the obtained uniform solution was sprayed in the form of a mist toward the liquid surface of 3000 parts of n-hexane being stirred using a spray gun for coating to precipitate a solute. The precipitated solid was separated by filtration, washed well with n-hexane, and then vacuum-dried at a temperature of 100 ° C. for 24 hours to obtain spherical epoxy-modified nylon particles A. The resulting epoxy modified nylon particles A by press-forming after a resin plate, in accordance with ASTM D 5045-96, the results of measuring the _{G Ic} value by compact tension method was 4420J / ^{m 2.}

  The number average particle diameter of each material was measured in accordance with “(1) Measurement of particle diameter of each of constituent elements [E] and [F] alone” in various evaluation methods described later.

  The number average particle size in the composition can be measured according to “(7) Measurement of particle size of each of constituent elements [E] and [F] in prepreg alone” in various evaluation methods described later.

(6) Component [F]: Conductive particles / phenol resin particles (Marilyn HF type, manufactured by Gunei Chemical Industry Co., Ltd.) were baked and classified at 2000 ° C. and classified conductive particles B (component: carbon, number (Average particle size: 33 μm)
・ “Glassy Carbon (registered trademark)” (component: carbon, number average particle size: 26 μm, manufactured by Tokai Carbon Co., Ltd.)
Conductive particles C (component: carbon, number average particle size: 23 μm) obtained by firing and classifying phenol resin particles (Marilyn HF type, manufactured by Gunei Chemical Industry Co., Ltd.) at 2000 ° C.
"Micropearl (registered trademark)" AU215 (component: particles obtained by plating nickel on divinylbenzene polymer particles and further gold plating thereon, number average particle size: 16 μm, manufactured by Sekisui Chemical Co., Ltd.)
Conductive particles D (component: carbon, number average particle size: 16 μm) obtained by firing and classifying phenol resin particles (Marilyn HF type, manufactured by Gunei Chemical Industry Co., Ltd.) at 2000 ° C.

  The number average particle diameter of each material was measured in accordance with “(1) Measurement of particle diameter of each of constituent elements [E] and [F] alone” in various evaluation methods described later.

  The number average particle size in the composition can be measured according to “(7) Measurement of particle size of each of constituent elements [E] and [F] in prepreg alone” in various evaluation methods described later.

(7) Component [G]: Carbon black “Printex (registered trademark)” L (component: furnace black, number average particle size of primary particles 23 nm, manufactured by Orion Engineered Carbons)
"ENSACO (registered trademark)" 250G (component: hollow furnace black, number average particle size of primary particles 25 nm, manufactured by Timcal Graphite & Carbon)
"Mitsubishi (registered trademark)" conductive carbon black # 3230B (component: furnace black, number average particle size of primary particles 23 nm, manufactured by Mitsubishi Chemical Corporation)
"Special Black (registered trademark)" 550 (component: furnace black, number average particle diameter of primary particles 25 nm, manufactured by Orion Engineered Carbons).

  In addition, the number average particle diameter of the primary particles of each material is measured according to “(2) Measurement of particle diameter of primary particles of component [G]” in various evaluation methods described later.

  The number average particle size in the composition can be measured according to “(8) Measurement of average particle size of primary particles of component [G] in prepreg” of various evaluation methods described later.

<Various evaluation methods>
(1) Constituent elements [E] and [F] each having a single particle size measurement For each of constituent elements [E] and [F], a laser microscope (ultra-depth color 3D shape measuring microscope VK-9510: manufactured by Keyence Corporation) The observation is performed by magnifying the particles to a magnification of 200 times or more and measuring the diameter of the circumscribed circle of 60 arbitrary particles as the particle size, and then averaging the values of the components [E] and [F] Each number average particle diameter was used.

(2) Particle size measurement of primary particles of component [G] Carbon black as component [G] is observed with a field emission scanning electron microscope (FE-SEM), and about 60 arbitrary particles, After measuring the diameter of the circumscribed circle of the particles as the particle diameter, the average value was taken as the number average particle diameter of the primary particles of the component [G].

(3) Measurement of carbon black structure size which is the constituent element [G] in the constituent element [B] The constituent elements [B], [C], [D] and [G] obtained in the respective examples and comparative examples An epoxy resin composition (primary resin) consisting of the following is poured into a mold, heated in a hot air oven from room temperature to 180 ° C. at a rate of 1.5 ° C. per minute, and then heated at 180 ° C. at 2 ° C. Holding the time, a 2 mm thick resin cured plate was produced. The obtained hardened plate was processed with a microtome and observed with a transmission electron microscope (TEM), and the average value was obtained after measuring the distance of the longest portion as the particle size for 60 arbitrary particles. The carbon black structure size as the constituent element [G] in the constituent element [B] was used.

(4) Viscosity measurement of epoxy resin composition Viscosity of epoxy resin composition (primary resin) comprising constituent elements [B], [C], [D] and [G] obtained in each of Examples and Comparative Examples Uses a dynamic viscoelastic device ARES-2KFRTN1-FCO-STD (manufactured by TA Instruments Inc.), a flat parallel plate with a diameter of 40 mm is used for the upper and lower measurement jigs, and the distance between the upper and lower jigs After setting the epoxy resin composition so as to be 1 mm, a measurement temperature range of 40 to 150 ° C. was measured at a heating rate of 1.5 ° C./min in a twist mode (measurement frequency: 0.5 Hz).

(5) Evaluation of components in a range corresponding to 13% of the prepreg average thickness from the prepreg surface The prepreg obtained in each Example and Comparative Example was placed between two smooth polytetrafluoroethylene resin plates on the surface. It was sandwiched and closely adhered, and the temperature was gradually raised to 150 ° C. over 7 days to gel and cure to produce a plate-like cured product. After curing, cut in a direction perpendicular to the contact surface (thickness direction), polish the cross section, and then enlarge it 200 times or more with an epi-illumination type optical microscope, and take a picture so that the upper and lower surfaces of the prepreg fit within the field of view. . The intervals between the polytetrafluoroethylene resin plates were measured at five locations in the lateral direction of the cross-sectional photograph, and the average value was taken as the average thickness of the prepreg.

  In addition, from this photograph, the presence or absence of carbon fibers as the constituent element [A] was confirmed in a range corresponding to 13% of the average thickness of the prepreg from the surface of the prepreg.

(6) Presence evaluation of each particle which is the constituent elements [E] and [F] existing in a depth range of 15% of the average thickness of the prepreg The prepregs obtained in the examples and comparative examples are The average thickness of the prepreg was measured by the method 5). In this photograph of the cured prepreg, two lines parallel to the surface of the prepreg are drawn from both surfaces of the cured prepreg at a depth of 15% of the average thickness of the prepreg. The total area of each particle of the constituent elements [E] and [F] existing in between and the total area of all the particles existing over the thickness of the prepreg are obtained, and the surface of the prepreg with respect to 100% of the prepreg thickness The abundance of particles existing in the range of 15% depth was calculated. Here, the total area of each particle was obtained by cutting out a particle portion from a cross-sectional photograph and converting it from its weight.

(7) Particle size measurement of each component [E] and [F] in the prepreg Each of the prepregs obtained by curing the prepregs obtained in each of the examples and comparative examples by the method of (5) is incident illumination. The image was magnified 200 times or more with a scanning optical microscope, and several photos were taken. Next, after measuring the particle diameters of 60 particles for each of the constituent elements [E] and [F] from the obtained cross-sectional photograph, the averaged value was determined as the number average particle diameter of each of the constituent elements [E] and [F]. did.

(8) Measurement of average particle diameter of primary particles of constituent element [G] in prepreg A prepreg obtained by curing the prepreg obtained in Examples and Comparative Examples by the method of (5) above is used as a focused ion beam (FIB). ) Thin piece processing was performed with an apparatus, and observation was performed with a transmission electron microscope (TEM). After measuring the particle size of 60 arbitrary particles, the average value was taken as the number average particle size.

(9) Volume content (Vf) measurement of carbon fiber in prepreg First, “prepreg mass per unit area, carbon fiber mass per unit area, resin mass content and fiber mass content described in JIS K7071 (1988). According to the test method, the carbon fiber mass per unit area is measured. Specifically, a test piece of 100 × 100 mm is cut out from the prepregs obtained in the respective examples and comparative examples, the thicknesses of arbitrary five points are measured, the average value is taken as the average thickness, and the volume is calculated. Next, at a temperature of 23 ° C., the test piece is put in a beaker, about 200 ml of methyl ethyl ketone (MEK) is put, and ultrasonic irradiation is performed for 15 minutes, followed by stirring. After the supernatant liquid is filtered using a glass filter whose mass has been measured in advance, MEK is put into a beaker in which the carbon fiber as the constituent element [A] remains, and the above operation is repeated three times. After completion of the third operation, the carbon fiber is also transferred to a glass filter and suction filtered. After filtration, the carbon fiber is dried together with a glass filter at a temperature of 105 ° C. for 90 minutes in a dryer, cooled in a desiccator for 45 minutes or more, and then the mass of the glass filter with the carbon fiber contained therein is measured. A value obtained by subtracting the mass of the glass filter measured in advance is defined as the mass of the carbon fiber. Using the density of the carbon fiber presented by the carbon fiber manufacturer, the volume is calculated from the mass of the carbon fiber obtained by the measurement. Vf was calculated by dividing the volume of the obtained carbon fiber by the volume of the test piece calculated first. The measurement was performed three times, and the average value was defined as Vf (volume%) of the prepreg.

(10) Method for measuring conductivity of fiber reinforced composite material The longitudinal direction of the carbon fibers contained in the prepregs obtained in the examples and comparative examples is 0 °, and [+ 45 ° / 0 ° / −45 ° / 90 °]. Are repeated two times based on the above, and a total of 16 ply pseudo-isotropic pre-laminated body is obtained. The obtained pre-laminated body was set in an autoclave, heated at a pressure of 0.6 MPa by 1.7 ° C. per minute from room temperature to 180 ° C., and cured at a temperature of 180 ° C. for 2 hours. Thus, a fiber reinforced composite material was obtained. A sample 40 mm long × 40 mm wide was cut out from the obtained fiber-reinforced composite material, the resin layers on both surfaces were polished and removed, and conductive paste N-2057 (manufactured by Shoei Chemical Industry Co., Ltd.) was applied to both sides. Was applied in a thickness of about 70 μm and cured in a hot air oven adjusted to a temperature of 180 ° C. over 30 minutes to obtain a sample for conductivity evaluation. The resistance in the thickness direction of the obtained sample was measured by a four-terminal method using an R6581 digital multimeter manufactured by Advantest Corporation. The measurement was performed 6 times, and the average value was defined as the volume resistivity (Ωcm) of the fiber composite material.

(11) Method for measuring post-impact compressive strength (CAI) of fiber reinforced composite material The longitudinal direction of the carbon fibers contained in the prepregs obtained in each Example and Comparative Example is defined as 0 °, and [+ 45 ° / 0 ° / −45 Based on [° / 90 °], those repeated three times are laminated symmetrically to make a total of 24 ply pseudo-isotropic pre-laminated body. The obtained pre-laminated body was set in an autoclave, heated at a pressure of 0.6 MPa by 1.7 ° C. per minute from room temperature to 180 ° C., and cured at a temperature of 180 ° C. for 2 hours. Thus, a fiber reinforced composite material was obtained. From the obtained fiber reinforced composite material, a rectangular test piece having a length of 150 mm and a width of 100 mm was cut out, and a falling weight impact of 6.7 J per mm of the thickness of the test piece was applied to the center of the test piece in accordance with JIS K 7089 (1996). Thereafter, the residual compressive strength was measured according to JIS K 7089 (1996). The measurement was performed 6 times, and the average value was defined as the compressive strength after impact (CAI) (MPa).

<Example 1>
A prepreg was produced by the following method.

(Preparation of carbon black masterbatch)
Add 80 parts of “Araldite (registered trademark)” GY282, which is an epoxy resin corresponding to component [B], and 20 parts of “Printex (registered trademark)” L, which is carbon black corresponding to component [G]. After lightly stirring, the carbon black was dispersed by passing 6 times through 3 rolls to obtain a carbon black masterbatch. The operation was performed in a room temperature environment.

(Primary resin formulation)
Into the kneading apparatus, the constituent element [B] shown in Table 1-1 (excluding the part contained in the carbon black master batch described above) and the constituent element [D] were added, and the temperature was raised to a temperature of 160 ° C. The mixture was heated and kneaded for 1 hour at a temperature of 160 ° C. to dissolve the component [D]. Next, the mixture was cooled to a temperature of 60 to 80 ° C. or lower, 8 parts of a carbon black master batch prepared in advance (including 1.6 parts of the carbon black component) was added, and the mixture was stirred for 1 hour.

  Next, while continuing kneading, the temperature was lowered to a temperature of 55 to 65 ° C., the component [C] shown in Table 1-1 was added, and the mixture was stirred for 30 minutes to obtain a primary resin of an epoxy resin composition.

  Regarding the obtained resin composition, in accordance with “(3) Measurement of carbon black structure size as component [G] in component [B]” in the various evaluation methods described above, the component in component [B] It was 180 nm when the carbon black structure size which is [G] was measured.

  In addition, as a result of measuring the viscosity according to “(4) Viscosity measurement of epoxy resin composition” of the various evaluation methods described above, the viscosity at a temperature of 70 ° C. is 31 Pa · s, and the condition (I) of the present invention is It was something to satisfy.

(Preparation of secondary resin)
Into the kneading apparatus, the constituent element [B] shown in Table 1-1 (excluding the part contained in the carbon black master batch described above) and the constituent element [D] were added, and the temperature was raised to a temperature of 160 ° C. The mixture was heated and kneaded for 1 hour at a temperature of 160 ° C. to dissolve the component [D]. Next, the mixture was cooled to a temperature of 60 to 80 ° C. or lower, 8 parts of a carbon black master batch prepared in advance (including 1.6 parts of the carbon black component) was added, and the mixture was stirred for 1 hour. Next, the component [E] shown in Table 1-1 was added and stirred for 30 minutes, and then the component [F] shown in Table 1-1 was added and stirred for 30 minutes. While continuing the kneading, the temperature was lowered to a temperature of 55 to 65 ° C., the component [C] described in Table 1-1 was added, and the mixture was stirred for 30 minutes to obtain a secondary resin of an epoxy resin composition.

(Preparation of prepreg)
The primary resin obtained above was applied onto release paper using a knife coater to prepare two resin films 1 having a resin basis weight of 36.5 g / m ² . Similarly, the secondary resin obtained above was applied onto release paper to produce two resin films 2 having a resin basis weight of 29 g / m ² .

Next, two pieces of the obtained resin film 1 are stacked on both sides of the carbon fiber on the carbon fiber as the constituent element [A] arranged in one direction so as to form a sheet having a fiber basis weight of 268 g / m ^2. The mixture was impregnated with an epoxy resin composition by heating and pressing under conditions of a temperature of 130 ° C. and a maximum pressure of 1 MPa to obtain a prepreg precursor.

  Two prepreg precursors were laminated on the obtained prepreg precursor from both sides of the prepreg precursor, and heated and pressurized under conditions of a temperature of 130 ° C. and a maximum pressure of 1 MPa to obtain a prepreg.

  As a result of measuring Vf according to "(9) Measurement of volume content (Vf) of carbon fiber in prepreg" of the above-described various evaluation methods, the obtained prepreg was 57% by volume and was suitable for structural members. Met.

The configuration of the constituent elements [B] to [G] in the obtained prepreg is as follows.
-Component [B];
“Araldite (registered trademark)” MY721: 55 parts,
“Araldite (registered trademark)” GY282: 10 parts,
GAN: 35 parts
-Component [C];
“Seika Cure (registered trademark)”: 42 parts,
-Component [D];
“VIRANTAGE (registered trademark)” VW-10700RFP: 20 parts,
-Component [E];
Nylon 12 particles SP-10: 27 parts,
-Component [F];
Conductive particles B: 1.7 parts,
-Component [G];
“Printex (registered trademark)” L: 1.6 parts The amount of the constituent element [C] is the active hydrogen contained in the constituent element [C] with respect to one epoxy group contained in the constituent element [B]. Is an amount such that 0.9 is 0.9.

(Evaluation of prepreg characteristics)
About the obtained prepreg, the evaluation of the components in the range corresponding to 13% of the prepreg average thickness from the prepreg surface was made in the above-mentioned various evaluation methods “(5) Configuration in the range corresponding to 13% of the prepreg average thickness. As a result of performing according to the “element evaluation”, the component [A] was not included. In addition, “(6) Average thickness of prepreg” in the various evaluation methods described above was used to determine the abundance of each particle as the constituent elements [E] and [F] existing in a range of 15% of the prepreg average thickness from the prepreg surface. As a result of performing according to the abundance evaluation of each particle which is the constituent elements [E] and [F] existing in the depth range of 15%, the constituent element [E] is 95% of the total amount of the constituent element [E]. The component [F] was 99% by mass relative to the total amount of the component [F].

(Evaluation of fiber reinforced composite material properties)
Using the obtained prepreg, fibers according to “(10) Method for measuring conductivity of fiber-reinforced composite material” and “(11) Method for measuring compressive strength after impact (CAI) of fiber-reinforced composite material” of the various evaluation methods described above As a result of conducting electrical conductivity and CAI measurement in the thickness direction of the panel obtained by producing the reinforced composite material, the volume resistivity value in the thickness direction was as low as 6.7 Ωcm, and the CAI was as high as 315 MPa.

<Examples 2-38>
A primary resin and a secondary resin, which are epoxy resin compositions, were prepared in the same manner as in Example 1 except that the composition was changed as shown in Tables 1-1 to 1-9, and a prepreg was prepared by a two-stage impregnation hot melt method. Then, a fiber reinforced composite material was produced and various measurements were performed.

In Examples 10, 11, 23, 24 and 29, the basis weight of the component [A] is 194 g / m ² , and in Examples 12, 13, 25, 26 and 30, the basis weight of the component [A] is 134 g / m ^2. It was changed to m ^2.

  The results of various measurements are as shown in Tables 1-1 to 1-9, and there is no problem in resin characteristics and prepreg characteristics even if the materials and blending ratio are varied within a predetermined range as in Examples 2-38. A fiber reinforced composite material having excellent electrical conductivity and impact resistance was obtained.

  Further, even when the basis weight of the component [A] was varied as in Examples 10-13, 23-26, 29, and 30, the obtained fiber-reinforced composite material showed excellent conductivity.

  As in Examples 37 and 38, even when the kneading time was controlled to change the structure size of the component [G] in the component [B], the obtained fiber-reinforced composite material had excellent conductivity and impact resistance. Showed sex.

<Comparative Examples 1-11>
A primary resin and a secondary resin, which are epoxy resin compositions, were prepared in the same manner as in Example 1 except that the composition was changed as shown in Tables 2-1 to 2-3. A prepreg was prepared by a two-stage impregnation hot melt method. Then, a fiber reinforced composite material was produced and various measurements were performed.

  In Comparative Examples 1 and 2, carbon black, which is the constituent element [G], was not blended, so a carbon black masterbatch was not produced, and the particle size distribution measurement of the carbon black structure was not performed.

  In Comparative Examples 3 and 4, the same carbon black masterbatch as in Example 31 was used.

Further, Comparative Example 6-7 was changed weight of the same configuration elements as in Example 10 to 13 [A] in 194 g / ^{m 2} and 134 g / ^{m 2.}

  Comparing Example 1 and Comparative Example 1, since Comparative Example 1 does not contain the components [F] and [G] that contribute to the conductivity in the thickness direction of the fiber-reinforced composite material, the resulting fiber-reinforced composite material It can be seen that the volume resistivity value in the thickness direction is high.

  Since Comparative Examples 2 and 3 contain only one of the constituent elements [F] and [G], the volume specific resistance value in the thickness direction of the fiber-reinforced composite material obtained is smaller than that of Comparative Example 1. However, it is inadequate, and when compared with Examples 2 and 5, it can be seen that the conductivity is improved by blending both the constituent elements [F] and [G].

  In Comparative Example 4, since the component [E] is not blended, it can be seen that the obtained fiber-reinforced composite material has a lower CAI than Example 3.

  Since Comparative Examples 5 to 7 use a material in which the particle size of the component [F] is out of the range defined in the present invention, for example, when compared with Examples 3, 11, and 13, the conductivity is increased. It turns out that it is inferior.

  In Comparative Examples 10 and 11, since the structure size in the component [B] of the carbon black that is the component [G] is outside the range defined in the present invention, the fiber-reinforced composite obtained when the structure size is small When the volume resistivity value with respect to the thickness direction of the material is high and the structure size is large, the viscosity of the primary resin becomes high and the impregnation property to the component [A] becomes poor. It turns out that it becomes low.

<Comparative Example 12>
As shown in Table 2-3, using the same primary resin as in Comparative Example 5, a prepreg was produced by the following one-stage impregnation hot melt method.

(Preparation of prepreg)
The primary resin obtained in Comparative Example 5 was applied onto release paper using a knife coater to produce two resin films 1 having a resin basis weight of 65.5 g / m ² .

Next, two pieces of the obtained resin film 1 are stacked on both sides of the carbon fiber on the carbon fiber as the constituent element [A] arranged in one direction so as to form a sheet having a fiber basis weight of 268 g / m ^2. The mixture was impregnated with an epoxy resin composition by heating and pressing under conditions of a temperature of 130 ° C. and a maximum pressure of 1 MPa to obtain a prepreg having a Vf of 52% by volume.

(Evaluation of prepreg characteristics)
The obtained prepreg was evaluated in the same manner as in Example 1. As a result, the constituent element [A] was included in a range corresponding to 13% of the prepreg average thickness from the prepreg surface. Further, the constituent elements [E] and [F] existing in the range of 15% of the prepreg average thickness from the prepreg surface were 0% by mass because they were not blended.

(Evaluation of fiber reinforced composite material properties)
As a result of conducting conductivity and CAI measurement in the thickness direction of the panel obtained by producing a fiber-reinforced composite material in the same manner as in Comparative Example 1, the volume specific resistance value in the thickness direction was as high as 1300 Ωcm, and the CAI was as low as 152 MPa. .

<Comparative Examples 13-23>
Except for changing the composition as shown in Tables 2-4 to 2-6, a primary resin and a secondary resin as an epoxy resin composition were prepared in the same manner as in Example 14, and a prepreg was prepared by a two-stage impregnation hot melt method. Then, a fiber reinforced composite material was produced and various measurements were performed.

  In Comparative Examples 13 and 14, since carbon black as the constituent element [G] was not blended, a carbon black masterbatch was not produced, and the particle size distribution measurement of the carbon black structure was not performed.

  In Comparative Examples 15 and 16, the same carbon black masterbatch as in Example 31 was used.

Further, Comparative Examples 18 and 19 were changed weight of the same configuration elements as Example 23~26,29,30 [A] in 194 g / ^{m 2} and 134 g / ^{m 2.}

  Comparing Example 14 and Comparative Example 13, since Comparative Example 13 does not contain the components [F] and [G] that contribute to the conductivity in the thickness direction of the fiber-reinforced composite material, the resulting fiber-reinforced composite material It can be seen that the volume resistivity value in the thickness direction is high.

  Since Comparative Examples 14 and 15 contain only one of the constituent elements [F] and [G], the volume specific resistance value in the thickness direction of the fiber-reinforced composite material obtained is smaller than that of Comparative Example 13. However, it is inadequate, and when compared with Examples 15 and 17, it can be seen that the conductivity is improved by blending both the constituent elements [F] and [G].

  Since Comparative Example 16 contains no component [E], it can be seen that the obtained fiber-reinforced composite material has a lower CAI than Example 16.

  Since Comparative Examples 17 to 19 use a material in which the particle size of the component [F] is outside the range defined in the present invention, for example, when compared with Examples 16, 24, and 26, the conductivity is increased. It turns out that it is inferior.

  In Comparative Examples 20 and 21, since the structure size in the component [B] of the carbon black that is the component [G] is outside the range defined in the present invention, the fiber-reinforced composite obtained when the structure size is small When the volume resistivity value with respect to the thickness direction of the material is high and the structure size is large, the viscosity of the primary resin becomes high and the impregnation property to the component [A] becomes poor. It turns out that it becomes low.

  In Comparative Example 22, since the blending amount of the carbon black as the constituent element [G] is larger than the range specified in the present invention, the dispersibility of the carbon black is lowered, and the structure size in the constituent element [B] is reduced. Increased, resulting in lower CAI of the composite material.

  In Comparative Example 23, since the blending amount of the carbon black as the constituent element [G] is less than the range defined in the present invention, the volume specific resistance value in the thickness direction of the fiber reinforced composite material is increased.

<Comparative Example 24>
As shown in Table 2-6, the same primary resin as in Comparative Example 5 was used, and a prepreg was produced by the same one-stage impregnation hot melt method as in Comparative Example 12.

  As a result of conducting conductivity and CAI measurement in the thickness direction of the panel obtained by producing a fiber-reinforced composite material in the same manner as in Comparative Example 1, the volume specific resistance value in the thickness direction was as high as 1300 Ωcm, and the CAI was as low as 152 MPa. .

<Comparative Example 25>
After preparing the primary resin and secondary resin which are epoxy resin compositions similarly to Example 1 except having changed the composition as shown in Table 2-7, and obtaining the prepreg by the two-stage impregnation hot melt method Then, a fiber-reinforced composite material was produced and various measurements were performed.

  In Comparative Example 25, the CAI is decreased and the volume resistivity is increased as compared with Example 1-21. This is because the component [G] is dispersed in the component [B] when the ratio of the component [G] increases in the mixing ratio of the master batch composed of a part of the component [B] and the component [G]. The viscosity of the master batch increased and the structure size of the component [G] also increased. As a result, since the impregnation property to the component [A] is deteriorated, it is considered that the CAI and conductivity of the obtained fiber-reinforced composite material are lowered.

Claims (13)

A prepreg including the following constituent elements [A] to [G], wherein a range corresponding to an average thickness of 13% of the prepreg from the surface of the prepreg is configured by the constituent elements [B] to [G]. E] and [F] of 85% by mass or more of each are present in a range corresponding to 15% of the average thickness of the prepreg from the surface of the prepreg, and the components [B] to [D] and [ G] satisfies the following condition (I).
[A]: Carbon fiber [B]: Epoxy resin having two or more glycidyl groups in one molecule [C]: Aromatic amine compound [D]: Thermoplastic resin composed of a polyaryl ether skeleton [E] Particles having a number average particle size of primary particles of 5 to 50 μm and having thermoplastic resin as a main component [F]: Conductive particles having a number average particle size of primary particles in the range of the following formula (1) [(F × 0.12) −3] ≦ P _size ≦ [(F × 0.12) +3] (1)
P _size : number average particle size (μm) of primary particles of conductive particles as constituent element [F]
F: Weight of component [A] in prepreg (g / m ² )
[G]: Carbon black in which the number average particle diameter of primary particles is 10 to 50 nm, and the size of the structure in which a plurality of primary particles are combined in the constituent element [B] is 100 to 500 nm. ): Component [C] in which the ratio of the number of epoxy groups in component [B] to the number of active hydrogens in component [C] is 1: 1 (0.7 ≦ l ≦ 1.3), Component [D] with a blending amount of m parts by mass (5 ≦ m ≦ 40) with respect to 100 parts by mass of component [B], and n parts by mass (1 ≦ n with respect to 100 parts by mass of component [B] The viscosity at a temperature of 70 ° C. of the resin composition composed of the constituent elements [B], [C], [D] and [G] including the constituent element [G] having a blending amount of ≦ 5) is 10 to 500 Pa · s. L, m, n must exist The prepreg of Claim 1 which contains 1-5 mass parts with respect to 100 mass parts of component [B] for component [G]. The prepreg according to claim 1 or 2, wherein the constituent element [F] is carbon particles. The prepreg in any one of Claims 1-3 which contains 0.5-10 mass parts of component [F] with respect to 100 mass parts of component [B]. The particle having the thermoplastic resin as a main component of the constituent element [E] is a particle having a blending ratio (mass%) of the thermoplastic resin and the thermosetting resin in a range of 95: 5 to 70:30. The prepreg according to any one of 1 to 4. The prepreg according to any one of claims 1 to 5, wherein the thermoplastic resin constituting the constituent element [E] is polyamide. The prepreg in any one of Claims 1-6 whose fiber volume content rate (Vf) of component [A] is 50-65 volume%. It is a method of manufacturing the prepreg in any one of Claims 1-7, Comprising: A part of component [B] and a component [G] are pre-kneaded, A part of component [B] and a component A master batch composed of [G] is prepared, and after mixing the master batch with the rest of the component [B] and the components [C] to [F], the component [A] is impregnated. The manufacturing method of a prepreg. The manufacturing method of the prepreg of Claim 8 whose component ratio [G] is 5-50 mass parts with respect to 100 mass parts of component [B] for the compounding ratio of a masterbatch. The manufacturing method of the prepreg of Claim 8 or 9 whose magnitude | size of the structure in which the primary particle of component [G] couple | bonded in the masterbatch is 100-500 nm. The manufacturing method of the prepreg in any one of Claims 8-10 whose surface resistivity of a masterbatch is 1 * 10 < ⁶ > (ohm) or less. Volume resistivity is not more than 10 .OMEGA.cm, fiber-reinforced composite material with respect to the thickness direction of the fiber-reinforced composite material obtained by heat curing the prepreg according to any one of claims 1 to 7.
The fiber-reinforced composite material according to claim 12, which has a compressive strength after impact (CAI) of 280 MPa or more.