JP5887963B2 - Prepreg and carbon fiber reinforced composites - Google Patents

Description

  The present invention relates to a carbon fiber reinforced composite material having excellent microcrack resistance, electrical conductivity, and impact resistance, and a prepreg suitably used therefor.

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

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

  As one of them, a prepreg in which resin fine particles are dispersed in a surface portion has been proposed. For example, there has been proposed a technique for providing a high-toughness composite material with good heat resistance by using a prepreg in which resin fine particles made of a thermoplastic resin such as nylon or insoluble rubber particles are dispersed on the surface (Patent Document) 1, 2, and 3). Separately, a technique has been proposed in which high toughness is expressed in a carbon fiber reinforced composite material by combining a matrix resin whose toughness has been improved by addition of a polysulfone oligomer and resin fine particles made of a thermosetting resin (Patent Document 4). reference). Since these technologies give a high impact resistance while producing a resin layer that becomes an insulating layer between the layers, among the conductivity that is one of the characteristics of the carbon fiber reinforced composite material, However, it has been difficult to achieve both excellent impact resistance and conductivity in a carbon fiber reinforced composite material.

  Therefore, as a method of solving the conductivity and impact resistance in the thickness direction of the carbon fiber reinforced composite material at once, a method of combining thermoplastic resin particles and conductive particles such as carbon particles and metal plating organic particles in advance with a matrix resin Has been proposed (see Patent Document 5). When a carbon fiber reinforced composite material having such a technique is used as an aircraft structural material, the carbon fiber reinforced composite material is used in a temperature range where repeated take-off and landing such as in an environment from an upper limit temperature of 71 ° C. to a lower limit temperature of −54 ° C. Even when the reinforced composite material is subjected to a high environmental load and there is no apparent damage, there is a large difference in linear expansion coefficient between the carbon particles and metal-plated organic particles and the matrix resin, and the matrix resin Distortion may be added. Due to this thermal strain, minute cracks of about several tens to several hundreds of micrometers starting from the interface between the carbon particles or metal-plated organic particles and the matrix resin, or the contact points between the carbon particles or metal-plated organic particles and the carbon fibers. (Microcracks) may occur, so there is no problem with short-term use. However, when long-term use is assumed, long-term environmental fatigue adds cracks inside the carbon fiber reinforced composite material. And transverse cracks could occur.

  In order to improve the microcrack resistance, for example, a core-shell rubber particle having high toughness is blended in a matrix resin as proposed in Patent Document 6, or a prepreg surface as proposed in Patent Documents 2 and 3 A method of blending insoluble rubber particles having higher toughness than thermoplastic resin particles is conceivable. However, when core-shell rubber particles are blended with a high-viscosity aircraft matrix resin, the core-shell rubber particles generally tend to agglomerate, and the compression characteristics of the carbon fiber reinforced composite material tend to decrease. On the other hand, even if insoluble rubber particles as proposed in Patent Documents 2 and 3 are simply blended in a matrix resin with low toughness, the cavitation effect of the insoluble rubber particles can be sufficiently exhibited due to insufficient toughness of the matrix resin. The carbon fiber reinforced composite material cannot exhibit the microcrack resistance. Furthermore, since the insoluble rubber particles do not have an appropriate particle size distribution and particle size with respect to the conductive particles, the interface between the carbon particles or the metal plating organic particles and the matrix resin, or the carbon particles or the metal plating organics. Since the contact location between the particles and the carbon fiber cannot be sufficiently increased in toughness, microcracks starting from these interfaces and contact locations cannot be prevented.

US Pat. No. 5,028,478 JP-A-1-118565 US Pat. No. 5,627,222 JP-A-3-26750 JP 2008-231395 A JP 2009-280669 A International Publication No. 2010/109929 Pamphlet

  Accordingly, an object of the present invention is to solve the above problems and obtain a carbon fiber reinforced composite material having excellent microcrack resistance, electrical conductivity, and impact resistance, and a prepreg suitably used for the carbon fiber reinforced composite material.

In order to achieve the above object, the present invention has one of the following configurations. That is,
A carbon fiber [A], a thermosetting resin [B], a conductive particle [C], and a prepreg satisfying at least one of the following (1) and (2), wherein the thermosetting resin [B], Thermosetting resin composition comprising conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D] and thermoplastic resin particles [E And a cured product obtained by curing the thermosetting resin composition at 180 ° C. for 2 hours with a K _IC of 0.8 to 2.0 MPa · m ^1/2 , conductive particles [C], rubber particles Both [D] and the thermoplastic resin particles [E] are 90 to 100% by mass of the total amount with respect to the thickness of the prepreg from both main surfaces of the prepreg in the thickness direction of the prepreg. Rubber particles [ ], Or the particle diameter of the rubber particle [D] and the diameter of the thermoplastic resin particle [E] that are not smaller are the median diameters of the conductive particles [C ] rather small equal to or than the median diameter of the particle size of the rubber particles [D] is in the case of measuring the particle size distribution by laser diffraction scattering method, when calculated cumulative curve of the total volume as 100%, the A prepreg having a particle size of 1 to 5 μm with a cumulative curve of 5% .
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E].

Alternatively, a prepreg satisfying at least one of carbon fiber [A], thermosetting resin [B], conductive particles [C], and the following (1) and (2), and thermosetting resin [B ], A thermosetting resin composition comprising conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D] and thermoplastic resin particles The cured product obtained by curing the thermosetting resin composition comprising [E] at a temperature of 180 ° C. for 2 hours has a K _IC of 0.8 to 2.0 MPa · m ^1/2 , and conductive particles [C], In each of the rubber particles [D] and the thermoplastic resin particles [E], 90 to 100% by mass of the total amount is from the main surface of one side of the prepreg to the thickness of the prepreg in the thickness direction of the prepreg. The rubber particles are distributed within a depth of 20%. D], or the particle diameter of the rubber particle [D] and the particle diameter of the thermoplastic resin particle [E] that are not smaller are the median diameters of the conductive particles [ C] rather small equal to or than the median diameter of particle size of, when the rubber particle [D] is in the case of measuring the particle size distribution by laser diffraction scattering method, of obtaining the cumulative curve of the total volume as 100%, The prepreg has a particle size of 1 to 5 μm with a cumulative curve of 5% .
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E].

  Moreover, the carbon fiber reinforced composite material of the present invention is obtained by a method comprising a step of heating and pressurizing a laminate comprising two or more of the above prepregs, of which at least two of the prepregs are adjacent.

  According to the present invention, a carbon fiber reinforced composite material that is excellent in fatigue resistance (microcrack resistance) due to thermal cycle in addition to conductivity in the thickness direction and that exhibits high impact resistance, and a prepreg suitable for obtaining the same. Can be obtained. In the prior art, it was possible to obtain a carbon fiber reinforced composite material that satisfies both impact resistance and electrical conductivity at the same time, but at the same time, it was possible to obtain a carbon fiber reinforced composite material suitable for an aircraft member having excellent microcrack resistance. There wasn't. According to the present invention, it becomes possible to provide a carbon fiber reinforced composite material excellent in microcrack resistance in addition to conductivity and impact resistance in the thickness direction, and structural materials for aircraft, space use, automobiles, ships, windmills, etc. Can be suitably used.

It is an example of sectional drawing of the typical prepreg (state in which 2 or more sheets were laminated | stacked) of this invention.

  As a result of pursuing a mechanism for developing microcrack resistance while simultaneously achieving both high impact resistance and conductivity for carbon fiber reinforced composite materials made of carbon fiber and thermosetting resin, the present inventors have as follows. Conductive particles are added to the laminated interlayer portion of the carbon fiber composite material to be described, and rubber particles are further arranged in the laminated interlayer portion. Alternatively, in addition to the conductive particles, thermoplastic resin particles are placed in the laminated interlayer portion. By arranging the rubber particles and causing the cavitation effect of the rubber particles to the maximum, by using a matrix resin having a specific toughness value, both excellent impact resistance and conductivity are added, and in addition microcracks It was discovered that a carbon fiber reinforced composite material having a high level of resistance could be obtained, and a prepreg from which such a carbon fiber reinforced composite material was obtained was conceived.

  A prepreg is a molded intermediate base material in which a reinforcing fiber is impregnated with a matrix resin. In the present invention, carbon fiber is used as the reinforcing fiber, and a thermosetting resin is used as the matrix resin. In such a prepreg, the thermosetting resin is in an uncured state, and a carbon fiber reinforced composite material can be obtained by laminating and curing the prepreg. Of course, a carbon fiber reinforced composite material can be obtained even if the prepreg monolayer is cured. In the carbon fiber reinforced composite material obtained by laminating and curing a plurality of prepregs, the surface portion of the prepreg becomes a laminated interlayer portion of the carbon fiber reinforced composite material, and the inside of the prepreg is inside the laminated layer of the carbon fiber reinforced composite material. Become. Hereinafter, the present invention will be described in detail.

The prepreg of the present invention is a prepreg formed by satisfying at least one of carbon fiber [A], thermosetting resin [B], conductive particles [C], and the following (1) and (2): Thermosetting resin composition comprising conductive resin [B], conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D] and The cured product obtained by curing the thermosetting resin composition comprising the thermoplastic resin particles [E] at 180 ° C. for 2 hours has a K _Ic of 0.8 to 2.0 MPa · m ^1/2 , and conductive particles [C], rubber particles [D], and thermoplastic resin particles [E] are all 90 to 100% by mass of the total amount from both main surfaces of the prepreg in the thickness direction of the prepreg. Distribution within a range of 20% depth relative to the thickness of the prepreg And that is a prepreg.
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E].

Alternatively, the prepreg of the present invention is a prepreg formed by satisfying at least one of carbon fiber [A], thermosetting resin [B], conductive particles [C], and the following (1) and (2): Thermosetting resin composition consisting of thermosetting resin [B], conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D And a cured product obtained by curing the thermosetting resin composition composed of the thermoplastic resin particles [E] at a temperature of 180 ° C. for 2 hours has a K _Ic of 0.8 to 2.0 MPa · m ^1/2 and is conductive. 90 to 100% by mass of the total amount of each of the conductive particles [C], the rubber particles [D], and the thermoplastic resin particles [E] is from one main surface of the prepreg in the thickness direction of the prepreg. Distribution within a range of up to 20% of the thickness of the prepreg And that is a prepreg.
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E].

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

  Commercially available products of such carbon fibers include “Torayca (registered trademark)” T800S-24K-10E, “Torayca (registered trademark)” T800G-24K-31E, and “Torayca (registered trademark)” T700SC-24K-50C. (All of these are manufactured by Toray Industries, Inc.).

  As for the form and arrangement of the carbon fibers [A], the arrangement is not limited as long as it is a continuous form, but in order to obtain a carbon fiber reinforced composite material that is lightweight and has a higher durability level, Are preferably in the form of continuous fibers such as long fibers, woven fabrics, bi-directional fabrics, multiaxial fabrics, nonwoven fabrics, mats, knits, braids, tows and rovings aligned in one direction.

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

  The carbon fiber [A] used in the present invention preferably has a single fiber fineness of 0.2 to 2.0 dtex, more preferably 0.4 to 1.8 dtex. If it is less than 0.2 dtex, the carbon fiber bundle may be easily damaged by the contact with the guide roller during twisting, and the same damage may occur in the impregnation process of the thermosetting resin. If it exceeds 2.0 dtex, the carbon fiber bundle may not be sufficiently impregnated with the thermosetting resin, and as a result, fatigue resistance may be reduced.

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

  The thermosetting resin [B] used in the present invention is not particularly limited as long as it undergoes a crosslinking reaction by heat and at least partially forms a three-dimensional crosslinked structure. Examples of such thermosetting resins include unsaturated polyester resins, vinyl ester resins, epoxy resins, cyanate resins, maleimide resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimide resins. A modified body and a blended resin of two or more types can also be used. In addition, these thermosetting resins may be self-curing by heating, or may be blended with a curing agent or a curing accelerator.

  Among these thermosetting resins [B], an epoxy resin having an excellent balance of heat resistance, mechanical properties, and adhesion to carbon fibers is preferably used. In particular, an epoxy resin whose precursor is an amine, a phenol, or a compound having a carbon-carbon double bond is preferably used.

  Specifically, tetraglycidyl diaminodiphenylmethane is mentioned as a tetraglycidyl amine type epoxy resin having amines as precursors. Examples of the aminophenol type epoxy resin include various isomers of triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, and triglycidylaminocresol. Tetraglycidyldiaminodiphenylmethane is preferably used because it is excellent in heat resistance and adhesion to carbon fibers.

  Especially as thermosetting resin [B], an average epoxy equivalent is 100-134 g / eq. Tetraglycidyldiaminodiphenylmethane is preferably used, and more preferably the average epoxy equivalent is 100 to 120 g / eq. More preferably, the average epoxy equivalent is 100 to 115 g / eq. It is. The average epoxy equivalent is 100 g / eq. If it does not satisfy the above, it may be difficult to produce tetraglycidyldiaminodiphenylmethane, the production yield may be low, and the average epoxy equivalent is 134 g / eq. If it exceeds 1, the viscosity of the resulting tetraglycidyldiaminodiphenylmethane will be too high, so only a small amount can be dissolved when the thermoplastic resin is dissolved to impart toughness to the thermosetting resin, and the thermosetting has high toughness. May not be obtained. Especially, an average epoxy equivalent is 100-120 g / eq. When a thermoplastic resin is dissolved in tetraglycidyldiaminodiphenylmethane, a large amount of thermoplastic resin can be dissolved within a range where there is no problem in the prepreg process, and high toughness is imparted to the cured product without impairing heat resistance. As a result, the carbon fiber reinforced composite material can exhibit high microcrack resistance.

  Further, when tetraglycidyldiaminodiphenylmethane is used as the thermosetting resin [B], it is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, out of 100 parts by mass of the thermosetting resin. More preferably, it is 35 parts by mass or more. If the amount of tetraglycidyldiaminodiphenylmethane is too small, the heat resistance and elastic modulus of the cured product of the thermosetting resin may decrease.

  Moreover, as a glycidyl aniline type epoxy resin preferably used as the thermosetting resin [B], one or more selected from the 2, 3, 4, 5, 6 positions of diglycidyl aniline, monoglycidyl aniline, and their benzene rings And a derivative group having a substituent on the carbon. Examples of the substituent include aryl groups such as alkyl groups, phenyl groups, and naphthyl groups, alkyl ether groups such as methoxy groups, and aryl ether groups such as phenoxy groups. By blending glycidyl aniline type epoxy resin, it is possible to control the viscoelasticity and fluidity of the resin and to improve the mechanical properties such as the elastic modulus of the cured resin and the tensile strength of the carbon fiber reinforced composite material. .

Further, as the thermosetting resin [B], a bisphenol type epoxy resin having phenol as a precursor is also preferably used. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and bisphenol S type epoxy resins. Further, novolak type epoxy resins such as phenol novolac type epoxy resin, cresol novolak type epoxy resin and resorcinol type epoxy resin are also preferably used.
Since the liquid bisphenol A type epoxy resin, bisphenol F type epoxy resin and resorcinol type epoxy resin have low viscosity, it is preferable to use them in combination with other epoxy resins.

  In addition, a bisphenol A type epoxy resin that is solid at room temperature (about 25 ° C.) gives a structure having a low crosslinking density in a cured resin compared to a bisphenol A type epoxy resin that is liquid at room temperature (about 25 ° C.). The cured resin is lower in heat resistance but higher in toughness, and is preferably used in combination with a glycidylamine type epoxy resin, a liquid bisphenol A type epoxy resin or a bisphenol F type epoxy resin. It is done.

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

  Urethane-modified epoxy resins and isocyanate-modified epoxy resins are preferably used because they give a cured resin having high fracture toughness and high elongation.

  These epoxy resins may be used alone or in combination as appropriate. It is preferable to mix and use at least a bifunctional epoxy resin and a trifunctional or higher functional epoxy resin since both the fluidity of the resin and the heat resistance after curing can be obtained. In particular, the combination of glycidylamine type epoxy and glycidyl ether type epoxy makes it possible to achieve both heat resistance and water resistance and processability. In addition, blending an epoxy resin that is liquid at least at room temperature and an epoxy resin that is solid at room temperature is effective for making the tackiness and draping property of the prepreg appropriate.

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

  Examples of commercially available epoxy resins that can be included in the thermosetting resin [B] will be given below.

  Examples of commercially available tetraglycidylamine epoxy resins include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldite (registered trademark)” MY720, “Araldite (registered trademark)” MY721, “Araldite (registered trademark)” MY9512, “ Araldite (registered trademark) “MY9663 (manufactured by Huntsman Advanced Materials)”, “Epototo (registered trademark)” YH-434 (manufactured by Toto Kasei Co., Ltd.), and the like.

  As a commercial product of a metaxylenediamine type epoxy resin, TETRAD-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) can be mentioned.

  Examples of commercially available 1,3-bisaminomethylcyclohexane type epoxy resins include TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Inc.).

  As a commercial product of an isocyanurate type epoxy resin, TEPIC-P (manufactured by Nissan Chemical Industries, Ltd.) can be mentioned.

  Commercially available products of aminophenol type epoxy resins include ELM120 and ELM100 (above, manufactured by Sumitomo Chemical Co., Ltd.), “jER (registered trademark)” 630 (manufactured by Mitsubishi Chemical Corporation), and “Araldite (registered trademark)”. MY0600, “Araldite (registered trademark)” MY0610, “Araldite (registered trademark)” MY0500, “Araldite (registered trademark)” MY0510 (manufactured by Huntsman Advanced Materials).

  As a commercially available product of the trishydroxyphenylmethane type epoxy resin, Tactix 742 (manufactured by Huntsman Advanced Materials) may be mentioned.

  As a commercial product of the tetraphenylolethane type epoxy resin, “jER (registered trademark)” 1031S (manufactured by Mitsubishi Chemical Corporation) can be mentioned.

  Examples of commercially available polyfunctional epoxy resins having a binaphthalene skeleton include “Epiclon (registered trademark)” HP4700 (manufactured by DIC Corporation).

  Commercially available polyfunctional epoxy resins containing a naphthalene skeleton include NC-7300 (manufactured by Nippon Kayaku Co., Ltd.), “Epototo (registered trademark)” ESN-175, “Epototo (registered trademark)” ESN-375 ( As mentioned above, Toto Kasei Co., Ltd.) is also included.

  Examples of commercially available dicyclopentadiene type epoxy resins include “Epiclon (registered trademark)” HP7200 (manufactured by DIC Corporation).

  Examples of commercially available phenol novolac epoxy resins include DEN431 and DEN438 (manufactured by Dow Chemical Co., Ltd.) and “jER (registered trademark)” 152 (manufactured by Mitsubishi Chemical Corporation).

  Examples of commercially available orthocresol novolak epoxy resins include EOCN-1020 (manufactured by Nippon Kayaku Co., Ltd.) and “Epiclon (registered trademark)” N-660 (manufactured by DIC Corporation).

  Commercially available products of bisphenol A type epoxy resins include “EPON (registered trademark)” 825 (manufactured by Mitsubishi Chemical Corporation), “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation), and “Epicron (registered trademark)”. ) “850 (manufactured by DIC Corporation)”, “Epototo (registered trademark)” YD-128 (manufactured by Tohto Kasei Co., Ltd.), DER-331, DER-332 (manufactured by Dow Chemical Co., Ltd.), etc. .

  As commercial products of solid bisphenol A type epoxy resin, “jER (registered trademark)” 1001, “jER (registered trademark)” 1002, “jER (registered trademark)” 1003, “jER (registered trademark)” 1004AF “jER” (Registered trademark) “1055”, “jER (registered trademark)” 1007, “jER (registered trademark)” 1009, and “jER (registered trademark)” 1010 (manufactured by Mitsubishi Chemical Corporation).

  Commercially available products of bisphenol F type epoxy resin include “jER (registered trademark)” 806, “jER (registered trademark)” 807 and “jER (registered trademark)” 1750 (above, manufactured by Mitsubishi Chemical Corporation), “Epiclon”. (Registered trademark) "830 (manufactured by DIC Corporation)" and "Epototo (registered trademark)" YD-170 (manufactured by Toto Kasei Corporation).

  Commercially available products of solid bisphenol F type epoxy resin include “jER (registered trademark)” 4002, “jER (registered trademark)” 4004P, “jER (registered trademark)” 4005P, “jER (registered trademark)” 4007P and “ jER (registered trademark) "4010P (above, manufactured by Mitsubishi Chemical Corporation)," Epototo (registered trademark) "YDF2001 (manufactured by Toto Kasei Co., Ltd.), and the like.

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

  Examples of commercially available biphenyl type epoxy resins include “jER (registered trademark)” YX4000 and “jER (registered trademark)” YL6677 (manufactured by Mitsubishi Chemical Corporation).

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

  A commercial product of a hydantoin type epoxy resin includes AY238 (manufactured by Huntsman Advanced Materials).

  Examples of commercially available epoxy resins having a bisarylfluorene skeleton include Ogsol PG, Ogsol PG-100, and Ogsol EG (manufactured by Osaka Gas Chemical Co., Ltd.).

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

  Examples of commercially available monofunctional epoxy resins include “Denacol (registered trademark)” Ex-731 (glycidyl phthalimide), “Denacol (registered trademark)” Ex-141 (phenylglycidyl ether), “Denacol (registered trademark)” Ex. -146 (p-tertiarybutylphenyl glycidyl ether), “Denacol (registered trademark)” Ex-147 (dibromophenyl glycidyl ether) (manufactured by Nagase ChemteX Corporation), and OPP-G (o-phenylphenyl) Glycidyl ether, manufactured by Sanko Co., Ltd.).

  As the epoxy resin used in the present invention, in addition to the above, it is also possible to use a copolymer of the above-described epoxy resin and other thermosetting resin, a modified body, and a resin composition obtained by blending two or more of these. it can.

  Examples of the thermosetting resin used by being copolymerized with an epoxy resin include unsaturated polyester resin, vinyl ester resin, epoxy resin, benzoxazine resin, phenol resin, urea resin, melamine resin, and polyimide resin. It is done. The thermosetting resin used by copolymerizing with an epoxy resin may be used alone or in combination of two or more.

  The epoxy resin curing agent is a compound having an active group capable of reacting with an epoxy group. The epoxy resin curing agent makes the crosslinking density appropriate when the resin composition is cured, and provides sufficient rigidity and heat resistance. The curing agent is not particularly limited as long as it has a functional group having reactivity with an epoxy group. More specifically, for example, dicyandiamide, aromatic polyamine, aminobenzoic acid esters, various acid anhydrides. , Phenol compounds, phenol novolac resins, cresol novolac resins, polyphenol compounds, imidazole derivatives, aliphatic amines, tetramethylguanidine, thiourea addition amines, carboxylic acid anhydrides such as methylhexahydrophthalic anhydride, carboxylic acid hydrazides, And Lewis acid complexes such as carboxylic acid amides, polymercaptans, and boron trifluoride ethylamine complexes.

  When the epoxy resin curing agent is an aromatic polyamine aromatic polyamine, an epoxy resin cured product with good heat resistance is obtained, which is preferable. Moreover, when an epoxy resin hardening | curing agent is an acid anhydride, since the hardened | cured material with a low water absorption is given compared with amine compound hardening, this is also preferable.

  Specific examples of the aromatic polyamine include diaminodiphenylsulfone, diaminodiphenylmethane, phenylenediamine, and various derivatives and positional isomers thereof. Examples of commercially available aromatic polyamine curing agents include “Seika Cure (registered trademark)” S (manufactured by Wakayama Seika Kogyo Co., Ltd.), MDA-220 (manufactured by Mitsui Chemicals, Inc.), and “jER Cure (registered trademark). ) "W (Mitsubishi Chemical Corporation), 3,3'-DAS (Mitsui Chemicals)", "Lonza Cure (registered trademark)" M-DIPA (Lonza Corporation), and "Lonza Cure" (Registered trademark) “M-MIPA (Lonza Co., Ltd.)” and the like.

  Specific examples of the acid anhydride curing agent include methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methyldihydronaphthic anhydride, methylnadic anhydride, cyclopentanetetra Examples thereof include carboxylic acid dianhydride, nadic anhydride, methyl nadic anhydride, bicyclo (2.2.2) oct-7-2,3,5,6-tetracarboxylic dianhydride. A commercially available product of methyltetrahydrophthalic anhydride is “Licacid (registered trademark)” MT500 (manufactured by Shin Nippon Rika Co., Ltd.). Commercially available products of hexahydrophthalic anhydride include “Licacid (registered trademark)” HH (manufactured by Shin Nippon Rika Co., Ltd.) and HHPA (manufactured by Maruzen Petrochemical Co., Ltd.). Commercial products of methylhexahydrophthalic anhydride include “EPICLON (registered trademark)” B-570, “EPICLON (registered trademark)” B-650 (manufactured by DIC Corporation), and the like. As a commercial product of a mixture of hexahydrophthalic anhydride and methylhexahydrophthalic acid, “Rikacid (registered trademark)” MH700 (Shin Nippon Rika Co., Ltd.) formulated with methylhexahydrophthalic anhydride: hexahydrophthalic anhydride = 70: 30 Co., Ltd.). A commercially available product of methyl nadic anhydride is “Kayahard (registered trademark)” MCD (manufactured by Nippon Kayaku Co., Ltd.). Examples of commercially available trialkyltetrahydrophthalic anhydride include “jER Cure (registered trademark)” YH-306 (manufactured by Mitsubishi Chemical Corporation).

  As the epoxy resin curing agent used in the present invention, in addition to those described above, those that make these curing agents latent, for example, amine adducts or microencapsulated ones can also be used. When such a latent curing agent is used, the storage stability of the prepreg, in particular, tackiness and draping properties are difficult to change even when left at room temperature, so for example, production of a large structure having a long lamination time Can also be obtained.

  These epoxy resin curing agents and the curing agents that have made them latent may be used singly or in appropriate combination of two or more. Along with the polyamines and acid anhydrides, secondary amines in which the amino groups of the polyamines are partially alkylated or arylated, secondary amines such as diphenylphenylenediamine, aniline derivatives, aminobiphenyls, aminoanthraquinones By using a combination of amino compounds having various ring structures such as phenylphenol and phenols, the mechanical properties such as tensile strength of carbon fiber reinforced composite materials and the elastic modulus and toughness of the cured resin are effectively improved. There are things you can do. Moreover, you may use combining the compound used as a curing catalyst according to a use and the objective.

  In order to exhibit good heat resistance and mechanical properties when cured as a thermosetting resin and a carbon fiber reinforced composite material, it contains an aromatic amine compound that is a solid at room temperature and has a melting point of 50 ° C. or more as a curing agent component. It is preferable. Of these, various derivatives of diaminodiphenylsulfone and various derivatives of diaminodiphenylmethane are preferably used. When a solid aromatic amine compound having a melting point of 50 ° C. or higher is used, it is preferably used as a fine powder, and even if the shape is spherical or irregular, there is no problem, but the average particle size is 0.5 to 100 μm. preferable. When the thickness is 0.5 μm or less, the powder may be dissolved in the epoxy resin when kneaded with the epoxy resin, and the physical properties in the final composite material may be lowered due to a gradual reaction before the curing process. In addition, the reaction may proceed during storage at room temperature or during lamination, and the prepreg tack or drape may be impaired. On the other hand, if it is 100 μm or more, it may remain undissolved even if it is heated in the curing process, and that portion may become a defect in the composite material.

  In the present invention, it is important to dissolve the thermoplastic resin [F] in the thermosetting resin [B] in order to improve mechanical properties, microcrack resistance, and solvent resistance. By blending a soluble thermoplastic resin with the thermosetting resin, the viscoelasticity of the matrix resin in the prepreg is controlled, and there is an effect of improving the handleability of the prepreg. Such a thermoplastic resin is generally selected from a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a thioether bond, a sulfone bond, and a carbonyl bond in the main chain. Although it is preferably a thermoplastic resin having a bond, it may have a partially crosslinked structure. Further, it may be crystalline or amorphous. In particular, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polyimide having phenyltrimethylindane structure, polysulfone, polyethersulfone, polyetherketone, polyetherether It is preferable that at least one resin selected from the group consisting of ketone, polyaramid, polyether nitrile, and polybenzimidazole is dissolved in the thermosetting resin. As these thermoplastic resins, commercially available polymers may be used, or so-called oligomers having a molecular weight lower than that of commercially available polymers may be used. As the oligomer, an oligomer having a functional group capable of reacting with a thermosetting resin at a terminal or in a molecular chain is preferable. From the viewpoint of affinity with the thermosetting resin used in the present invention, these thermoplastic resins have a functional group capable of reacting with a thermosetting resin such as a hydroxyl group or an amino group or a curing agent component thereof at the end or molecule. It is preferable to have in the chain. By having a functional group capable of reacting with the thermosetting resin or its curing agent component, it becomes easy to prevent non-uniformity due to separation and precipitation during curing, and the solvent resistance can be further improved.

  Polyethersulfone and polyetherimide are preferably used from the viewpoints of heat resistance and toughness of the cured product of the thermosetting resin and viscosity control of the uncured thermosetting resin. Ethersulfone is particularly preferably used.

  Among them, polyethersulfone having an average molecular weight of 10,000 to 60000 g / mol is preferably used, more preferably the average molecular weight is 12000 to 50000 g / mol, and still more preferably the average molecular weight is 15000 to 30000 g / mol. If the average molecular weight is too low, tackiness of the prepreg may be excessive and handleability may be reduced, or the toughness of the cured product may be reduced. If the average molecular weight is too high, the tackiness of the prepreg may be reduced to deteriorate the handleability, or the resin may have a high viscosity when dissolved in a thermosetting resin, and may not be converted into a prepreg. In particular, when a polyethersulfone having a high heat resistance with an average molecular weight of 15000 to 30000 g / mol is dissolved in a thermosetting resin, a large amount of the thermoplastic resin is converted into a thermosetting resin as long as there is no problem in the prepreg process. It can be dissolved in the resin, high toughness can be imparted to the cured product, and high microcrack resistance can be imparted to the carbon fiber reinforced composite material while maintaining heat resistance and impact resistance.

  As commercially available products of polyethersulfone, "Sumika Excel (registered trademark)" PES3600P, PES5003P, PES5200P, PES7600P (above, manufactured by Sumitomo Chemical Co., Ltd.), "Ultrason (registered trademark)" E2020P, E2020P SR, E6020P (above (Manufactured by BASF), “Virantage” (registered trademark) PESU VW-10200, “Virantage” (registered trademark) PESU VW-10700 (registered trademark, above, Solvay Advance Polymers Co., Ltd.), and polyetherimide include “ “Ultem” (registered trademark) 1000, “Ultem” (registered trademark) 1010, “Ultem” (registered trademark) 1040 (manufactured by SABIC Innovative Plastics Japan LLC), and the like can be used.

  When the thermoplastic resin [F] is dissolved and used in the thermosetting resin [B], better results are obtained than when they are used alone. The brittleness of the thermosetting resin is covered with the toughness of the thermoplastic resin, and the molding difficulty of the thermoplastic resin is covered with the thermosetting resin, thereby providing a balanced base resin. Of 100 parts by mass of the thermosetting resin [B], the blending ratio of the thermoplastic resin is preferably 2 to 40 parts by mass, more preferably 5 to 30 parts by mass, and further preferably 12 to 25 parts by mass. It is a range. When the amount of the thermoplastic resin is too large, the viscosity of the thermosetting resin composition increases, and the processability and handleability of the thermosetting resin composition and the prepreg may be impaired. If the amount of the thermoplastic resin is too small, the toughness of the cured product of the thermosetting resin may be insufficient, and the resulting carbon fiber reinforced composite material may have insufficient microcrack resistance.

  As a combination of the thermosetting resin [B] and the thermoplastic resin [F] of the present invention, tetraglycidyldiaminodiphenylmethane, which is excellent in heat resistance and adhesion to carbon fibers, and polyether, which is excellent in heat resistance and toughness A combination with sulfone is preferably used because the resulting cured product has high heat resistance and toughness. In particular, an average epoxy equivalent of 100 to 115 g / eq. The combination of tetraglycidyldiaminodiphenylmethane and polyethersulfone having an average molecular weight of 15,000 to 30000 g / mol can dissolve a large amount of polyethersulfone having high heat resistance in tetraglycidyldiaminodiphenylmethane, thus reducing heat resistance. High toughness can be imparted to the cured product obtained without any problem, and high microcrack resistance can be imparted to the carbon fiber reinforced composite material while maintaining heat resistance and impact resistance.

  The thermoplastic resin particles [E] of the present invention can realize excellent impact resistance in the obtained carbon fiber reinforced composite material. As the raw material of the thermoplastic resin particles used in the present invention, the same kind as the thermoplastic resins exemplified above as the thermoplastic resin used by being dissolved in the epoxy resin, and in the form of particles are used. be able to. Among these, polyamides that can greatly improve the impact resistance of the carbon fiber reinforced composite material due to excellent toughness are most preferable. Among polyamides, Nylon 6, Nylon 12, Nylon 11 and Nylon 6/12 copolymers have particularly good adhesive strength with thermosetting resins. The peel strength is high, and the impact resistance improvement effect is high, which is preferable. In the case of using particles prepared by further mixing an epoxy resin as the thermoplastic resin particles, it is more preferable because the adhesion to the epoxy resin as the matrix resin is improved and the impact resistance of the carbon fiber reinforced composite material is improved. As commercial products of polyamide particles, “Amilan (registered trademark)” SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80 (manufactured by Toray Industries, Inc.), “Orgasol ( Registered trademark) "1002D, 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D (above, manufactured by Arkema Co., Ltd.) and the like can be used. The shape of these thermoplastic resin particles may be spherical, non-spherical, porous, needle-shaped, whisker-shaped, or flake-shaped, but since the spherical shape does not deteriorate the flow characteristics of the epoxy resin, the carbon fiber is reduced. Is excellent in impregnating properties, and during defalling weight impact (or local impact) on carbon fiber reinforced composite material, delamination caused by local impact is further reduced, so carbon fiber reinforced composite after such impact When a stress is applied to the material, a carbon fiber reinforced composite material exhibiting a high impact resistance can be obtained with fewer delamination portions caused by the local impact that is the starting point of fracture due to stress concentration. To preferred. Further, some thermoplastic resin particles exhibit a higher modification effect by not being dissolved in the matrix resin component during the curing process. Not dissolving during the curing process is also effective in improving the impregnation property while maintaining the fluidity of the resin at the time of curing.

The median diameter of the thermoplastic resin particles [E] is not less than the median size of the rubber particles [D] described below, or the same as the median diameter of the conductive particles [C] described later, have smaller than that. When the thermoplastic resin particles are larger than the median diameter of the conductive particles, the carbon fiber reinforced composite material has an insulating thermosetting resin composition sandwiched between adjacent carbon fibers. In some cases, the conductive particles are buried between the adjacent carbon fibers, and a conductive path between the conductive particles contained between the adjacent carbon fibers and the carbon fibers is not easily formed, so that a sufficient conductivity improvement effect may not be obtained. . The median diameter of the thermoplastic resin particles [E] is preferably at most 150 μm. When the average diameter exceeds 150 μm, when the carbon fiber arrangement is disturbed or the thermoplastic resin particles are formed in the vicinity of the surface of the prepreg, the resulting carbon fiber reinforced composite material is made thicker than necessary. Therefore, the mechanical properties such as the compression properties of the carbon fiber reinforced composite material may be lowered. The median diameter is preferably 1 to 150 μm, more preferably 1 to 70 μm, and still more preferably 1 to 30 μm. If the median diameter is too small, the particles will sink between the fibers of the carbon fiber, and will not be localized in the interlayer part of the prepreg laminate, so that the presence effect of the particles cannot be obtained sufficiently, and the resulting carbon fiber reinforced composite material Impact resistance may be reduced.
Rubber particle [D] of the present invention, it is possible to realize a high impact resistance and microcracks resistant carbon fiber reinforced composite material obtained.
As the rubber particles used in the present invention, known natural rubber or synthetic rubber can be used. In particular, crosslinked rubber particles insoluble in the thermosetting resin are preferably used. If it is insoluble in the thermosetting resin, the heat resistance of the cured product becomes equivalent to the heat resistance of the cured product of the thermosetting resin not containing particles. Moreover, since the morphology does not change depending on the type of thermosetting resin and the curing conditions, stable physical properties of the cured thermosetting resin such as toughness can be obtained. As the crosslinked rubber particles, for example, a copolymer of a single or a plurality of unsaturated compounds, or particles obtained by copolymerizing a single or a plurality of unsaturated compounds and a crosslinkable monomer can be used. .
Examples of unsaturated compounds include aliphatic olefins such as ethylene and propylene, aromatic vinyl compounds such as styrene and methylstyrene, conjugated diene compounds such as butadiene, dimethylbutadiene, isoprene, and chloroprene, methyl acrylate, propyl acrylate, and acrylic acid. Unsaturated carboxylic acid esters such as butyl, methyl methacrylate, propyl methacrylate and butyl methacrylate, vinyl cyanide such as acrylonitrile, and the like can be used. Further, epoxy resins such as carboxyl group, epoxy group, hydroxyl group and amino group, amide group, or compounds having a functional group reactive with a curing agent can be used. As examples, acrylic acid, glycidyl methacrylate, vinylphenol, vinylaniline, acrylamide and the like can be used.
As an example of the crosslinkable monomer, a compound having a plurality of polymerizable double bonds in the molecule such as divinylbenzene, diallyl phthalate, and ethylene glycol dimethacrylate can be used.
These particles can be produced by various conventionally known polymerization methods such as an emulsion polymerization method and a suspension polymerization method. A typical emulsion polymerization method is a method in which an unsaturated compound or a crosslinkable monomer is subjected to emulsion polymerization in the presence of a radical polymerization initiator such as a peroxide, a molecular weight regulator such as a mercaptan or a halogenated hydrocarbon, and an emulsifier. In this method, after reaching the polymerization conversion rate, a reaction stopper is added to stop the polymerization reaction, and then the unreacted monomer in the polymerization system is removed by steam distillation or the like to obtain a copolymer latex. Water is removed from the latex obtained by the emulsion polymerization method to obtain crosslinked rubber particles.

Examples of the crosslinked rubber particles include crosslinked acrylonitrile butadiene rubber particles, crosslinked styrene butadiene rubber particles, acrylic rubber particles, and core shell rubber particles. A core-shell type rubber particle is a spherical polymer particle composed of a polymer having a different central part and surface layer part, and is simply composed of a two-phase structure of a core phase and a single shell phase, or, for example, soft core, hard shell, soft There are known multi-core shell rubber particles having a multi-phase layer structure having a plurality of shell phases such as a shell and a hard shell. Here, “soft” means the rubber phase described above, and “hard” means a resin phase that is not rubber. Here, as a commercial product of crosslinked rubber particles, as a specific example of crosslinked acrylonitrile butadiene rubber (NBR) particles, X
ER-91 (manufactured by JSR Co., Ltd.), “DuoMod (registered trademark)” DP5045 (manufactured by Zeon Corporation), and the like. Specific examples of the crosslinked styrene butadiene rubber (SBR) particles include XSK-500 (manufactured by JSR Corporation). Specific examples of the acrylic rubber particles include Methbrene W300A and W450A (manufactured by Mitsubishi Rayon Co., Ltd.), and specific examples of the core-shell type rubber particles include Staphyloid AC3832, AC3816N (manufactured by Gantz Kasei Co., Ltd.), METABLEN KW-4426 (manufactured by Mitsubishi Rayon Co., Ltd.), EXL-2611, EXL-3387 (manufactured by Rohm and Haas Co., Ltd.), “Paraloid (registered trademark)” EXL-2655, “Paraloid (registered trademark) ) “EXL-2314” (manufactured by Kureha Chemical Industry Co., Ltd.), “Staffroid (registered trademark)” AC-3355, “Staffroid (registered trademark)” TR-2105, “Staffroid (registered trademark)” TR -2102, "Staffyroid (registered trademark)" TR-2122, "Staffyroid (registered trademark)" I -101, “Staffyroid (registered trademark)” IM-203, “Staffyroid (registered trademark)” IM-301, “Staffyroid (registered trademark)” IM-401 (above, manufactured by Takeda Pharmaceutical Co., Ltd.), etc. Is mentioned. The crosslinked rubber particles may be used alone or in combination of two or more.

The median diameter of the rubber particle [D] of the present invention is the case where the thermoplastic resin particle [E] is not used, or the case where the thermoplastic resin particle [E] is used, and the median diameter of the rubber particle [D] is If not less than the median diameter of the thermoplastic resin particles [E], or the same as the median diameter of the conductive particles [C] described later, it has smaller than that. When the rubber particles are larger than the median diameter of the conductive particles, in the carbon fiber reinforced composite material, an interlayer having an insulating thermosetting resin composition sandwiched between adjacent carbon fibers In some cases, the conductive particles are buried, and a conductive path between the conductive particles contained between adjacent carbon fibers and the carbon fibers is not easily formed, so that a sufficient conductivity improving effect is not obtained. The median diameter of the rubber particles [D] is preferably 150 μm at most. When the median diameter exceeds 150 μm, when the carbon fiber arrangement is disturbed or the thermoplastic resin particles are formed in the vicinity of the surface of the prepreg, the resulting carbon fiber reinforced composite material has an unnecessarily thick interlayer. Therefore, the mechanical properties such as the compression properties of the carbon fiber reinforced composite material may be lowered. The median diameter is preferably 1 to 150 μm, more preferably 1 to 70 μm, and still more preferably 1 to 30 μm. If the median diameter is too small, the particles will sink between the fibers of the carbon fiber, and will not be localized in the interlayer part of the prepreg laminate, so that the effect of existence of the rubber particles cannot be obtained sufficiently, and the resulting carbon fiber reinforced composite material The impact resistance of the may be reduced. When the median diameter of the rubber particles is 1 to 30 μm, the rubber particles are disposed around the conductive particles of the present invention between the layers of the carbon fiber reinforced composite material, and the carbon fiber reinforced composite is sufficiently toughened. It is possible to prevent micro cracks starting from the interface between the matrix resin and the conductive particles or the contact portion between the conductive particles and the carbon fibers between the layers of the materials.

  When the particle size distribution of the rubber particle [D] of the present invention is measured by the laser diffraction scattering method and the cumulative curve is obtained with the total volume being 100%, the particle size at which the cumulative curve becomes 5% It is preferable that it is 10 micrometers. When such a particle size exceeds 10 μm, the tough rubber particles are not properly disposed so as to surround the conductive particles of the present invention, and the matrix resin and the conductive particles are interposed between the layers of the carbon fiber reinforced composite material. There may be a case where a microcrack starting from the interface or the contact point between the conductive particles and the carbon fiber occurs. The particle size at which the cumulative curve is 5% is preferably 1 to 10 μm, more preferably 1 to 8 μm, and further preferably 1 to 5 μm. If the particle size at which the cumulative curve is 5% is too small, rubber particles will be caught between the carbon fiber fibers, and will not be localized in the interlayer part of the prepreg laminate, and the presence effect of the particles cannot be obtained sufficiently. The resulting carbon fiber reinforced composite material may have low impact resistance. When the particle size at which the cumulative curve of rubber particles [D] is 5% is 1 to 5 μm, rubber particles [D] are placed around the conductive particles [C] of the present invention between the layers of the carbon fiber reinforced composite material. Can efficiently enter and sufficiently toughen, so that between the layers of the carbon fiber reinforced composite material, the interface between the matrix resin and the conductive particles [C], or the conductive particles [C] and the carbon fibers [A] It is particularly preferably used because it can prevent microcracks starting from the contact points.

  When the particle size distribution is measured by the laser diffraction scattering method, the coefficient of variation (CV value) of the particle size of the rubber particles [D] is preferably 30% or more. More preferably, it is 35% or more, More preferably, it is 40% or more. When the CV value is too small, the production cost of the rubber particles may be increased, or when the median diameter of the rubber particles is large, the tough rubber particles are appropriately disposed so as to surround the conductive particles. In some cases, microcracks starting from the interface between the matrix resin and the conductive particles or the contact point between the conductive particles and the carbon fiber may occur between the layers of the carbon fiber reinforced composite material. By optimizing the CV value, rubber particles can reinforce the interface between the matrix resin and the conductive particles or the contact points between the conductive particles and the carbon fibers between the layers of the carbon fiber reinforced composite material. Microcracks can be prevented.

The term “particle size” as used herein means the particle size at each volume% in a cumulative curve where the total volume is 100% when the particle size distribution is measured by the laser diffraction scattering method. The particle size distribution used in the present invention is measured by a laser diffraction / scattering method using LA-950 manufactured by HORIBA Co., Ltd. using a laser diffraction / scattering method. The particle size at 5% and 50% (median diameter) in each volume% in the cumulative curve of the obtained particle size distribution is obtained. Further, the CV value (coefficient of variation of particle size) used in the present invention is calculated by the following calculation formula.
CV value (%) of particle size = (standard deviation of particle size / median diameter) × 100.

The conductive particles [C] used in the present invention may be any particles that behave as electrically good conductors, and are not limited to those consisting only of conductors. Preferably, the particles have a volume resistivity of 10 to 10 ⁻⁹ Ωcm, more preferably 1 to 10 ⁻⁹ Ωcm, and still more preferably 10 ⁻¹ to 10 ⁻⁹ Ωcm. If the volume resistivity is too high, sufficient conductivity may not be obtained in the carbon fiber reinforced composite material. The conductive particles include, for example, conductive polymer particles such as carbon particles, metal particles, polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaphthene particles, and polyethylenedioxythiophene particles, as well as the core of an inorganic material. Particles formed by coating with a conductive substance and particles formed by covering the core of an organic material 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 substance, and particles in which the core of an organic material is coated with a conductive substance are included because of high conductivity and stability. Among these, carbon particles are particularly preferably used because of their high long-term stability.

  The volume resistivity mentioned here is calculated from the sample thickness and resistance value measured by setting the sample in a cylindrical cell having four probe electrodes and applying a pressure of 60 MPa to the sample. It is set as the volume specific resistance.

  The carbon particles can be obtained, for example, by firing thermosetting resin particles or thermoplastic resin particles. The firing temperature is preferably 600 ° C to 3000 ° C, more preferably 800 ° C to 3000 ° C, and still more preferably 2000 ° C to 3000 ° C. When fired at a temperature of 2000 ° C. or higher, carbon particles having excellent conductivity can be obtained. Examples of the thermosetting resin particles include phenol resin particles, epoxy resin particles, and benzoxazine particles. Examples of thermoplastic resin particles include polyacrylonitrile particles, polyetherimide particles, polyamideimide particles, polyphenylene sulfide particles, polyamide particles, polyimide particles, polyether ketone particles, and polyethersulfone particles. Is used. Of these, phenol resin particles are particularly preferably used because the carbon particles obtained have high conductivity.

  Examples of the carbon particles include “Bellepearl (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 (manufactured by Tokai Carbon Co., Ltd.), high purity artificial graphite SG series, SGB series, SN series (manufactured by SEC Carbon Co., Ltd.), true spherical carbon (manufactured by Gunei Chemical Industry Co., Ltd.) ) And the like. Furthermore, when the sphericity of the carbon particles is 0.8 to 1.0, stress is not concentrated at the time of impact, which is preferable because of high impact resistance.

  The conductive material used when coating the core of the inorganic material or the core of the organic material to form conductive particles is only required to contain a material that is an electrically good conductor, such as platinum. Metals such as gold, silver, copper, nickel, titanium, cobalt, palladium, tin, zinc, iron, chromium, aluminum, conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyisothianaphthene, polyethylenedioxythiophene Carbon such as carbon black, carbon black, carbon black, carbon nanotubes, fullerenes, graphene, hollow carbon fibers, etc. can be used. Among these, metal and carbon are particularly preferably used because of high conductivity.

  When a metal is used as the conductive substance, any metal may be used, but the standard electrode potential is preferably −2.0 to 2.0 V, more preferably −1.8 to 1.8 V. If the standard electrode potential is too low, it may be unstable and unfavorable for safety, and if it is too high, workability and productivity may be reduced. Here, the standard electrode potential refers to the electrode potential when a metal is immersed in a solution containing the metal ions and the standard hydrogen electrode (platinum immersed in a 1N HCl solution in contact with hydrogen gas at 1 atm. Electrode) expressed as a difference from the potential. For example, Ti: -1.74V, Ni: -0.26V, Cu: 0.34V, Ag: 0.80V, Au: 1.52V.

When using the said metal, it is preferable that it is the metal used by plating. As a preferable metal, platinum, gold, silver, copper, tin, nickel, titanium, cobalt, zinc, iron, chromium, aluminum, etc. are used because it can prevent corrosion of the metal due to a potential difference with the carbon fiber, and among these, Platinum, gold, silver, copper, tin, nickel, or titanium is particularly preferably used since the volume resistivity shows high conductivity and stability of 10 to 10 ⁻⁹ Ωcm. In addition, these metals may be used independently and may be used as an alloy which has these metals as a main component.

  As a method of performing metal plating using the above metal, wet plating and dry plating are preferably used. As the wet plating, methods such as electroless plating, displacement plating, and electroplating can be employed. Among them, the method using electroless plating is preferably used because plating can be applied to nonconductors. It is done. As the dry plating, methods such as vacuum deposition, plasma CVD (chemical vapor deposition), photo CVD, ion plating, and sputtering can be adopted. However, since excellent adhesion can be obtained even at a low temperature, the sputtering method is used. Is preferably used.

  The metal plating may be a single metal film or a multi-layer film made of a plurality of metals. When metal plating is performed, it is preferable that a plating film having an outermost layer made of gold, nickel, copper, or titanium is formed. By using the above-mentioned metal as the outermost surface, the connection resistance value can be reduced and the surface can be stabilized. For example, when forming a gold layer, a method of forming a nickel layer by electroless nickel plating and then forming a gold layer by displacement gold plating is preferably used.

  It is also preferable to use metal fine particles as the conductive substance constituting the conductive layer. In this case, the metal used as the metal fine particles is platinum, gold, silver, copper, tin, nickel, titanium, cobalt, zinc, iron, chromium, aluminum, or these because it prevents corrosion due to a potential difference with the carbon fiber. An alloy mainly containing tin, tin oxide, indium oxide, indium oxide / tin (ITO), or the like is preferably used. Among these, platinum, gold, silver, copper, tin, nickel, titanium, or an alloy containing these as a main component is particularly preferably used because of high conductivity and stability. Here, the fine particles refer to particles having a median diameter smaller than the median diameter of conductive particles (usually, 0.1 times or less).

  A mechanochemical bonding method is preferably used as a method for coating the nucleus with the above-mentioned metal fine particles. Mechanochemical bonding is a method of creating composite fine particles by adding mechanical energy to mechanically bond multiple different material particles at the molecular level, creating strong nanobonds at the interface, In the present invention, metal fine particles are bonded to the nuclei of an inorganic material or an organic material, and the nuclei are covered with the metal fine particles.

  In the case where metal nuclei are coated on the core of an inorganic material or an organic material (including a thermoplastic resin), the particle size of the metal fine particle is preferably 1/1000 to 1/10 times the median diameter of the nuclei, more preferably Is 1/500 to 1/100 times. In some cases, it is difficult to produce fine metal particles having a particle size that is too small. Conversely, if the particle size of the fine metal particles is too large, uneven coating may occur. In some cases, it is difficult to produce fine metal particles having a particle size that is too small. Conversely, if the particle size of the fine metal particles is too large, uneven coating may occur.

  When carbon is used as the conductive material, crystalline carbon and amorphous carbon are preferably used, and carbon black such as channel black, thermal black, furnace black, ketjen black, carbon nanotube, fullerene, graphene, hollow Carbon fiber or the like is preferably used. Among these, hollow carbon fibers are preferably used, and the outer shape thereof is preferably 0.1 to 1000 nm, more preferably 1 to 100 nm. Even if the outer diameter of the hollow carbon fiber is too small or too large, it is often difficult to produce such a hollow carbon fiber.

  The hollow carbon fiber may have a graphite layer formed on the surface. In that case, the total number of the graphite layers to be formed is preferably 1 to 100 layers, more preferably 1 to 10 layers, still more preferably 1 to 4 layers, and particularly preferably 1 to 2 layers. belongs to.

  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 particular, if a thermoplastic resin is used as the organic material and particles in which the core of the thermoplastic resin is coated with the conductive substance are employed, even better impact resistance can be realized in the obtained carbon fiber reinforced composite material. Therefore, it is preferable.

  In the type of conductive particles coated with a conductive substance, the conductive particles are composed of a core inorganic material or organic material and a conductive layer made of a conductive substance, and if necessary, the core and An adhesive layer as described later may be provided between the conductive layers.

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

  In the case of conductive particles in which the core of the thermoplastic resin is coated with a conductive substance, the carbon fiber reinforced composite material exhibits high impact resistance and conductivity without adding the thermoplastic resin particles [E]. Therefore, by using this together with the thermoplastic resin particles [E], or the thermoplastic resin particles [E] and the rubber particles [D], it is possible to develop higher impact resistance and conductivity. Can do.

The thermoplastic resin used as the core material of the conductive particles [C] used in the present invention is the same as the various thermoplastic resins exemplified above as the thermoplastic resin used by being dissolved in the thermosetting resin. be able to. Among them, it is preferable to use a thermoplastic resin having a strain energy release rate (G _1c ) of 1500 to 50000 J / m ² as a core material. More preferably, 3000~40000J / ^{m 2,} more preferably 4000~30000J / ^{m 2.} If the strain energy release rate (G _1c ) is too small, the impact resistance of the carbon fiber reinforced composite material may be insufficient, and if it is too large, the rigidity of the carbon fiber reinforced composite material may decrease. As such a thermoplastic resin, for example, polyamide, polyamideimide, polyethersulfone, polyetherimide and the like are preferably used, and polyamide is particularly preferable. Among polyamides, nylon 6, nylon 12, nylon 11 and nylon 6/12 copolymer are preferably used. Evaluation of G _1c is performed by a compact tension method or a double tension method defined in ASTM D 5045-96 using a resin plate obtained by molding a thermoplastic resin that is a core material of conductive particles.

  In the type of conductive particles [C] coated with a conductive substance, an adhesive layer may or may not exist between the core and the conductive layer, but the core and the conductive layer are likely to peel off. May be present. The main components of the adhesive layer in this case are vinyl acetate resin, acrylic resin, vinyl acetate-acrylic resin, vinyl acetate-vinyl chloride resin, ethylene-vinyl acetate resin, ethylene-vinyl acetate resin, ethylene-acrylic resin, polyamide. , Polyvinyl acetal, polyvinyl alcohol, polyester, polyurethane, urea resin, melamine resin, phenol resin, resorcinol resin, epoxy resin, polyimide, natural rubber, chloroprene rubber, nitrile rubber, urethane rubber, SBR, recycled rubber, butyl rubber, aqueous vinyl urethane , Α-olefin, cyanoacrylate, modified acrylic resin, epoxy resin, epoxy-phenol, butyral-phenol, nitrile-phenol, etc. are preferred, among which vinyl acetate resin, acrylic resin, vinyl acetate Le - acrylic resin, vinyl acetate - vinyl chloride resins, ethylene - vinyl acetate resins, ethylene - vinyl acetate resins, ethylene - include acrylic resins and epoxy resins.

  In the conductive particles [C] of the type coated with a conductive substance, the conductive particles coated with the conductive substance are represented by [volume of nucleus] / [volume of conductive layer]. The volume ratio is preferably 0.1 to 500, more preferably 1 to 300, and still more preferably 5 to 100. If the volume ratio is less than 0.1, not only the mass of the obtained carbon fiber reinforced composite material is increased, but also there are cases where the carbon fiber reinforced composite material cannot be uniformly dispersed during resin preparation. In some cases, sufficient conductivity cannot be obtained in the composite material.

  The specific gravity of the conductive particles in which the nuclei of the conductive particles [C] used in the present invention are coated with a conductive substance is preferably at most 3.2. If the specific gravity of the conductive particles exceeds 3.2, not only will the mass of the resulting carbon fiber reinforced composite material increase, but there may be cases where it cannot be uniformly dispersed during resin preparation. From this viewpoint, the specific gravity of the conductive particles is preferably 0.8 to 2.2. If the specific gravity of the conductive particles is less than 0.8, it may not be uniformly dispersed during resin preparation.

  The shape of the conductive particles [C] may be spherical, non-spherical, porous, needle-shaped, whisker-shaped, or flake-shaped. However, since the spherical shape does not deteriorate the flow characteristics of the thermosetting resin, the carbon fiber Excellent impregnation property. In addition, when falling weight impact (or local impact) on the carbon fiber reinforced composite material, delamination caused by the local impact is further reduced, so stress was applied to the carbon fiber reinforced composite material after such impact. In some cases, there are fewer delaminations caused by the local impact, which is the starting point of fracture due to stress concentration, and between the carbon fiber reinforced composite layers, the carbon fiber and the conductivity in the layer Since the probability of contact with the particles is high and a conductive path is easily formed, it is preferable in that a carbon fiber reinforced composite material that exhibits high impact resistance and conductivity is obtained.

  In the present invention, the conductive particles [C] may have low adhesion to the thermosetting resin [B], but if these are subjected to a surface treatment, strong adhesion to the thermosetting resin is possible. Can be achieved, and the impact resistance can be further improved. From this point of view, it is preferable to apply a material that has been subjected to at least one treatment selected from the group consisting of coupling treatment, oxidation treatment, ozone treatment, plasma treatment, corona treatment, and blast treatment. In particular, those that have been subjected to surface treatment by coupling, oxidation, or plasma treatment that can form a chemical bond or hydrogen bond with an epoxy resin in a thermosetting resin can realize strong adhesion to the thermosetting resin. More preferably used.

  In the surface treatment, the surface treatment can be performed using heating and ultrasonic waves in order to help shorten the surface treatment time and disperse the conductive particles. The heating temperature is at most 200 ° C, preferably 30 to 120 ° C. That is, if the temperature is too high, the odor becomes strong and the environment may deteriorate, or the operating cost may increase.

  In the present invention, the mass ratio represented by [the amount of rubber particles [D] (parts by mass)] / [the amount of conductive particles [C] (parts by mass)] is preferably 1-1000. More preferably, it is 10-500, More preferably, it is 10-100. When the mass ratio is less than 1, sufficient impact resistance may not be obtained in the obtained carbon fiber reinforced composite material. When the mass ratio is greater than 1000, in the obtained carbon fiber reinforced composite material. In some cases, sufficient conductivity cannot be obtained.

Moreover, the mass ratio represented by [total amount (parts by mass)] of [rubber particles [D] and thermoplastic resin particles (parts by mass)] / [total amount (parts by mass) of conductive particles [C]] is 1-1000. It is preferable that it is, More preferably, it is 10-500, More preferably, it is 10-100. When the mass ratio is less than 1, sufficient impact resistance may not be obtained in the obtained carbon fiber reinforced composite material. When the mass ratio is greater than 1000, in the obtained carbon fiber reinforced composite material. In some cases, sufficient conductivity may not be obtained. In the present invention, the median diameter of the conductive particles [C] is preferably at most 150 μm. When the median diameter exceeds 150 μm, when the carbon fiber arrangement is disturbed or the thermoplastic resin particles are formed in the vicinity of the surface of the prepreg, the resulting carbon fiber reinforced composite material has an unnecessarily thick interlayer. Therefore, the mechanical properties such as the compression properties of the carbon fiber reinforced composite material may be lowered. The median diameter of the conductive particles is preferably 1 to 150 μm, more preferably 10 to 70 μm, and further preferably 15 to 40 μm. If the median diameter is too small, the particles will sink between the fibers of the carbon fiber, and will not be localized in the interlayer part of the prepreg laminate, so that the effect of existence of the rubber particles cannot be obtained sufficiently, and the resulting carbon fiber reinforced composite material The impact resistance of the may be reduced. When the median diameter of the conductive particles is 15 to 40 μm, the carbon fiber-reinforced composite material has a high contact probability between the carbon fibers and the conductive particles in the stacked layers, and is easy to form a conductive path. This is preferable in that a carbon fiber reinforced composite material that exhibits impact resistance and conductivity is obtained.

  For the thermosetting resin composition in which the conductive particles [C] are the thermosetting resin [B], the conductive particles [C] and the rubber particles [D], or the thermosetting resin [B], the conductive Carbon fiber reinforced composite material obtained to be 0.01 to 50% by mass with respect to the thermosetting resin composition comprising the conductive particles [C], the rubber particles [D], and the thermoplastic resin particles [E] Is preferable because it exhibits excellent conductivity. More preferably, it is 0.05-10 mass%, More preferably, it is 0.1-5 mass%. For the thermosetting resin composition in which the conductive particles [C] are the thermosetting resin [B], the conductive particles [C] and the rubber particles [D], or the thermosetting resin [B], the conductive In the resulting carbon fiber reinforced composite material when the content is less than 0.01% by mass with respect to the thermosetting resin composition comprising the conductive particles [C], the rubber particles [D], and the thermoplastic resin particles [E]. In some cases, it is difficult to form a path and a sufficient effect of improving conductivity is not obtained. When the amount exceeds 50% by mass, sufficient impact resistance may not be obtained in the obtained carbon fiber reinforced composite material.

  The CV value of the particle size of the conductive particles [C] of the present invention is preferably 20% or less, more preferably 15% or less, and further preferably 10% or less. When the CV value of the particle size of the conductive particles [C] exceeds 20%, the probability that the conductive particles come into contact with each carbon fiber between the carbon fiber layers of the carbon fiber reinforced composite material is decreased, and thus obtained. The conductivity of the carbon fiber reinforced composite material may not be improved.

  In the combination of the conductive particles [C] and the rubber particles [C] of the present invention, the conductive particles having a particle size CV value of 10% or less and the rubber particles having a particle size CV value of 40% or more. The combination has a high contact probability between the carbon fibers in the laminated layer and the conductive particles between the laminated layers of the carbon fiber reinforced composite material, easily forms a conductive path, and the rubber particles are appropriately arranged around the conductive particles. Therefore, it is preferable in that a carbon fiber reinforced composite material that exhibits high microcrack resistance and high conductivity is obtained.

Suppresses thermal strain of thermosetting resin due to thermal cycle, peeling of interface between conductive particles and matrix resin, or microcracks starting from contact points between conductive particles and carbon fibers, and microcracks are generated In order to prevent the development of the cured product, and to fully develop the cavitation effect of the rubber particles in the cured thermosetting resin, the cured product of the thermosetting resin composition should have a high fracture toughness value. It is done. In the present invention, a thermosetting resin composition comprising a thermosetting resin [B], conductive particles [C] and rubber particles [D], or a thermosetting resin [B], conductive particles [C], rubber The stress intensity factor K _{Ic in} the opening mode of the cured product obtained by curing the thermosetting resin composition composed of the particles [D] and the thermoplastic resin particles [E] at a temperature of 180 ° C. for 2 hours is 0.8-2. is a 0MPa ^{· m 1/2,} preferably 1.0~1.5MPa ^{· m 1/2.} When such K _Ic is smaller than 0.8 MPa · m ^1/2 , generation of microcracks due to thermal cycling cannot be sufficiently suppressed. On the other hand, when it exceeds 2.0 MPa · m ^1/2 , the viscosity of the thermosetting resin composition is remarkably improved, and a prepreg cannot be produced, or the elastic modulus of the cured product is lowered.

By blending the rubber particles [D] with the thermosetting resin [B] and the conductive particles [C] of the present invention, the crack progress starting from the interfacial peeling between the conductive particles and the thermosetting resin becomes remarkable. It is preferably used in that it can be suppressed and a higher _KIc can be obtained than the thermoplastic resin particles [E]. Further, by combining the thermoplastic resin particles [E] with the thermosetting resin [B], the conductive particles [C], and the rubber particles [D], the thermoplastic resin particles are laminated between the laminated layers of the carbon fiber reinforced composite material. It is possible to obtain a carbon fiber reinforced composite material having excellent impact resistance from the high adhesion between the resin and the thermosetting resin.

  In order to obtain the thermosetting resin composition of the prepreg of the present invention, components other than the conductive particles [C], the rubber particles [D], the thermoplastic resin particles [E] and the curing agent are uniformly formed at about 150 ° C. It is preferable to knead by heating and kneading and cooling to a temperature at which the curing reaction hardly proceeds, and then kneading by adding conductive particles [C], rubber particles [D], thermoplastic resin particles [E] and a curing agent. The blending method is not particularly limited to this method.

  The prepreg used in the present invention has a particle-rich layer, that is, when the cross section thereof is observed, the above-described particles (conductive particles [C], rubber particles [D], and thermoplastic resin particles [E]) are localized. It is preferable that the layer (hereinafter sometimes abbreviated as a particle layer) in which the existing and present state can be clearly confirmed is formed in the vicinity of the surface of the prepreg.

  In this way, when the prepreg is laminated and the thermosetting resin [B] is cured by forming a structure in which the particles are unevenly distributed on the surface side, a prepreg layer, that is, carbon fiber is obtained. A resin layer is easily formed between the layers of the reinforced composite material, thereby enhancing the adhesion and adhesion between the layers of the carbon fiber reinforced composite material, and the resulting carbon fiber reinforced composite material exhibits high impact resistance. Become so.

  From such a viewpoint, the particle layer has a thickness of 100% of the prepreg, from the surface of the prepreg, starting from the surface, from each of both main surfaces of the prepreg, or from one main surface of the prepreg. The thickness of the prepreg should be 20% deep, preferably 10% deep. When laminating two or more prepregs, when the particle layer of the prepreg is present only on one side, the prepreg is preferably laminated so that the surface on which the particle layer is present faces in the same direction. On the other hand, when the particle layer is present only on one side of the prepreg, the prepreg can be front and back, so care must be taken when laminating. That is, if the prepreg is placed so that there is an interlayer with and without particles, there is a possibility of becoming a carbon fiber reinforced composite material that is weak against impact. Therefore, in order to eliminate the distinction between the front and back and facilitate lamination, The particle layer should be present on both the front and back sides of the prepreg.

  Further, the ratio of the conductive particles [C] and the rubber particles [D] existing in the particle layer, or the presence of the conductive particles [C], the rubber particles [D] and the thermoplastic resin particles [E]. The ratio of the conductive particles [C] and the rubber particles [D] or the conductive particles [C], the rubber particles [D], and the thermoplastic resin particles [E] in the prepreg is 100% by mass based on the total amount. It is 90-100 mass%, Preferably it is 95-100 mass%.

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

  In the present invention, the total amount of the conductive particles [C] and the rubber particles [D] or the conductive particles [C], the rubber particles [D], and the thermoplastic resin particles [E] is 20 masses based on the prepreg. % Or less is preferable. When the total amount exceeds 20% by mass with respect to the prepreg, mixing with the base resin becomes difficult and tackiness and drape of the prepreg may be deteriorated. That is, in order to impart impact resistance while maintaining the characteristics of the base resin, the total amount of such particles is preferably 20% by mass or less, more preferably 15% by mass or less, based on the prepreg. In order to further improve the handling of the prepreg, the content is more preferably 10% by mass or less. In order to obtain high impact resistance and electrical conductivity, the total amount of such particles is preferably 1% by mass or more, more preferably 2% by mass or more with respect to the prepreg.

  The prepreg of the present invention can be produced by applying a method as disclosed in JP-A-1-26651, JP-A-63-170427 or JP-A-63-170428. Specifically, the prepreg of the present invention has conductive particles [C] and rubber particles [D] on the surface of a primary prepreg composed of carbon fibers [A] and a thermosetting resin [B] that is a matrix resin, or , Conductive particles [C], rubber particles [D] and thermoplastic resin particles [E] are applied as they are, these conductive particles and rubber particles in a thermosetting resin as a matrix resin, or conductive In the process of preparing a thermosetting resin composition in which particles, rubber particles and thermoplastic resin particles are uniformly mixed, and impregnating the composition with carbon fibers, carbon fibers, conductive particles and rubber particles, or conductive A method of localizing particles on the surface portion of the prepreg by blocking intrusion of particles, rubber particles and thermoplastic resin particles, or by impregnating a carbon fiber with a thermosetting resin in advance to form a primary prepreg A thermosetting resin composition containing a high concentration of these conductive particles and rubber particles, or conductive particles, rubber particles, and thermoplastic resin particles in a thermosetting resin on the primary prepreg surface. It can manufacture by the method of sticking this film. Conductive particles and rubber particles, or conductive particles, rubber particles, and thermoplastic resin particles are uniformly present in the depth range of 20% of the prepreg thickness, resulting in impact resistance, conductivity and microcrack resistance. Thus, a prepreg for a carbon fiber composite material having both of the above is obtained.

  When the prepreg of the present invention was cured at a temperature of 180 ° C. for 2 hours to obtain a carbon fiber reinforced composite material, the temperature upper limit value 71 ° C., the temperature lower limit value −54 ° C., the holding time at each temperature for 3 minutes, It is preferable that the number of microcracks at the time of 3200 cycles of the thermal cycle test at 10 ° C. per 1 minute for the temperature raising / lowering rate is 10 or less, more preferably 5 or less, and still more preferably 1 or less. When the number of such microcracks exceeds 10, the microcracks generated in a dense manner are combined with adjacent cracks by being repeatedly loaded, and grow into cracks that cross the carbon fiber bundle, so-called transverse cracks. In some cases, the compression characteristics of the carbon fiber reinforced composite material after a certain amount of fatigue may be significantly reduced. Arrangement of conductive particles between layers of carbon fiber reinforced composite material to provide lightning strike resistance and the provision of a carbon fiber and conductive path within the layer is due to the linear expansion of matrix resin and conductive particles between layers. Since the coefficients are different, it is considered that the possibility of the occurrence of microcracks is further increased due to the influence of thermal strain caused by the heat cycle load. Further, when the adhesiveness between the conductive particles and the matrix resin is weak due to the load of the thermal cycle, the interface peeling occurs and the possibility of the occurrence of micro cracks is further increased. Moreover, there is a possibility that microcracks starting from the contact points between the conductive particles and the carbon fibers may be generated due to the heat cycle load. In the prepreg of the present invention, conductive particles are added to the laminated interlayer portion of the carbon fiber composite material, and further rubber particles are arranged, or in addition to the conductive particles, thermoplastic resin particles and rubber particles are arranged, and rubber By using a matrix resin having a specific toughness value in order to maximize the particle cavitation effect, a carbon fiber reinforced composite material having microcrack resistance can be obtained even under a thermal cycle load.

  When the prepreg of the present invention is cured at a temperature of 180 ° C. for 2 hours to obtain a carbon fiber reinforced composite material, the conductive particles [C of 30% or more between the layers of adjacent carbon fibers [A] [C] ] Are preferably in contact with the respective carbon fibers. If the conductive particles are not in contact with the respective carbon fibers between the layers of the carbon fiber reinforced composite material, or if the number of conductive particles is less than 30% between the layers of the carbon fiber reinforced composite material, When not in contact with the fibers, the conductivity of the carbon fiber reinforced composite is difficult because it is difficult to form conductive particles contained between adjacent carbon fibers and the conductive paths of those continuous carbon fibers. May not improve sufficiently. In order to sufficiently improve the conductivity of the carbon fiber reinforced composite material, the ratio of the number of conductive particles in contact with each carbon fiber in the laminated layer between the laminated layers of the carbon fiber reinforced composite material is determined by the conductive path. Is preferably 30% or more, more preferably 50% or more, and still more preferably 70% or more.

  The carbon fiber reinforced composite material of the present invention includes two or more of the prepregs of the present invention described above, and pressurizes and heats a laminate in which at least two of the prepregs are adjacent to each other, thereby thermosetting resin A method for curing the composition can be produced as an example. By using a combination of conductive particles [C] and rubber particles [D], or conductive particles [C], rubber particles [D] and thermoplastic resin particles [E], carbon fiber reinforced composite material can be obtained. During falling weight impact (or local impact), delamination caused by local impact is reduced, so when stress is applied to the carbon fiber reinforced composite material after such impact, it becomes the starting point of fracture due to stress concentration There are few delamination parts caused by the local impact. Furthermore, it is preferable that the glass transition temperature Tg of the hardened | cured material obtained by heating the thermosetting resin composition used for 2 hours at 180 degreeC is 180 degreeC or more. When the Tg is 180 ° C. or higher, the obtained carbon fiber reinforced composite material is excellent in that it can be applied to an aircraft structural member.

  Such a carbon fiber reinforced composite material of the present invention is widely used for aerospace applications, general industrial applications and the like because of its excellent strength, rigidity, impact resistance, electrical conductivity and microcrack resistance. More specifically, in aerospace applications, primary aircraft structural materials such as main wings, tail wings and floor beams, secondary aircraft structural materials such as flaps, ailerons, cowls, fairings and interior materials, rocket motor cases and artificial It is preferably used for satellite structural materials. Among such aerospace applications, the carbon fiber reinforced composite material according to the present invention is used in aircraft primary structure applications that particularly require impact resistance, lightning resistance, and microcrack resistance, particularly in fuselage skin, main wing skin, and tail wing skin. Particularly preferably used. In general industrial applications, structural materials for moving bodies such as automobiles, ships, and railway vehicles, drive shafts, leaf springs, windmill blades, pressure vessels, flywheels, paper rollers, roofing materials, cables, reinforcing bars, ICs It is preferably used for computer applications such as trays and notebook computer housings (housing) and civil engineering and building material applications such as repair and reinforcement materials. Among these, the carbon fiber reinforced composite material according to the present invention is particularly preferably used in automobile skins, ship skins, railway skins, windmill blades, and IC trays and notebook PC housings (housings).

  FIG. 1 is an example of a cross-sectional view of a typical prepreg of the present invention. A more specific description will be given with reference to FIG.

  The prepreg of the present invention shown in FIG. 1 includes a thermosetting resin 6, rubber particles 1 and conductive particles 4 between two carbon fiber layers 3 composed of carbon fibers 5 and a thermosetting resin 6. A particle layer 2 is provided. The formation of the particle layer 2 increases the toughness between the carbon fiber layers, and the conductive particles 4 included in the particle layer 2 can form a conductive path between the carbon fiber layers. High impact resistance and electrical conductivity are developed. In the particle layer, rubber particles are appropriately arranged around the conductive particles. Therefore, between the layers of the obtained carbon fiber reinforced composite material, the interface between the thermosetting resin and the conductive particles, or the conductive particles and the carbon. It is possible to prevent microcracks starting from the contact points with the fibers.

Hereinafter, the prepreg and carbon fiber reinforced composite material of the present invention will be described more specifically with reference to examples. The production environment and evaluation of the prepregs of the following examples are performed in an atmosphere at a temperature of 25 ° C. ± 2 ° C. and a relative humidity of 50% unless otherwise specified. Further, the present invention is not limited to these examples. Examples 2, 3, 31, and 33 are examples of the present invention, and Examples 1, 4 to 30, 32, 34 , and 35 are reference examples.

<Carbon fiber [A]>
"Torayca (registered trademark)" T800S-24K-10E (carbon fiber with 24,000 fibers, tensile strength 5.9 GPa, tensile elastic modulus 290 GPa, tensile elongation 2.0%, manufactured by Toray Industries, Inc.).
-"Torayca (registered trademark)" T700S-24K-50C (carbon fiber with 24,000 fibers, tensile strength 4.9 GPa, tensile elastic modulus 230 GPa, tensile elongation 2.1%, manufactured by Toray Industries, Inc.).

<Thermosetting resin [B]>
-Bisphenol A type epoxy resin, “jER (registered trademark)” 825 (manufactured by Japan Epoxy Resin Co., Ltd.) (EEW: 175 g / eq.).
-Bisphenol F type epoxy resin, EPICLON830 (DIC Corporation) (EEW: 172 g / eq.).
Tetraglycidyldiaminodiphenylmethane, ELM434 (manufactured by Sumitomo Chemical Co., Ltd.) (DIC Corporation) (EEW: 126 g / eq.).
Tetraglycidyldiaminodiphenylmethane, “Araldite (registered trademark)” MY721 (manufactured by Huntsman Advanced Materials) (EEW: 110 g / eq.).
Triglycidyl-p-aminophenol, MY0510 (manufactured by Huntsman Advanced Materials) (EEW: 101 g / eq.).
Triglycidyl-m-aminophenol, MY0610 (manufactured by Huntsman Advanced Materials) (EEW: 98 g / eq.).
-N, N-diglycidyl aniline, GAN (made by Nippon Kayaku Co., Ltd.).
-4,4'-diaminodiphenyl sulfone, "Seika Cure (registered trademark)"-S (manufactured by Wakayama Seika Co., Ltd.).
-3,3'-diaminodiphenyl sulfone, 3,3'-DAS (manufactured by Mitsui Chemicals Fine).

<Conductive particles [C]>
“Micropearl (registered trademark)” CU225 (manufactured by Sekisui Chemical Co., Ltd.) (median diameter: 25 μm, CV value: 4%).
“Micropearl (registered trademark)” AU225 (manufactured by Sekisui Chemical Co., Ltd.) (median diameter: 25 μm, CV value: 5%).
“Micropearl (registered trademark)” AU215 (manufactured by Sekisui Chemical Co., Ltd.) (median diameter: 15 μm, CV value: 5%).
"NICABEADS (registered trademark)" ICB-2020 (manufactured by Nippon Carbon Co., Ltd.) (median diameter: 27 µm, CV value: 10%)
The above particles were used after repeated classification and the above conditions.
-Glassy carbon (manufactured by Tokai Carbon Co., Ltd.) (median diameter: 26 μm, coefficient of variation: 30%)
<Rubber particles [D]>
“DuoMod (registered trademark)” DP5045 particles A (Zeon Corporation) (median diameter: 23 μm, particle diameter at which cumulative curve is 5%: 8 μm, CV value: 65%).
“DuoMod®” DP5045 particles B (median diameter: 13 μm, particle size at which cumulative curve is 5%: 5 μm, CV value: 15%).

The above particles were used after repeated classification and the above conditions.
“DuoMod (registered trademark)” DP5045 particles C (median diameter: 12 μm, particle diameter at which cumulative curve is 5%: 2 μm, CV value: 51%).

The above particles were used after repeated classification and the above conditions.
“DuoMod®” DP5045 particles D (median diameter: 16 μm, particle size at which cumulative curve is 5%: 12 μm, CV value: 10%).

The above particles were used after repeated classification and the above conditions.
XER-91 (manufactured by JSR Corporation) (median diameter: 3 μm, particle diameter at which the cumulative curve becomes 5%: 0.2 μm, CV value: 38%).

<Thermoplastic resin particles [E]>
Nylon 12 particles SP-500 (manufactured by Toray Industries, Inc., shape: true sphere) (median diameter: 5 μm).
-Epoxy-modified nylon particles A obtained by the following production method
90 parts by mass of transparent polyamide (trade name “Grillamide (registered trademark)”-TR55, manufactured by Mzavelke), 7.5 parts by mass of epoxy resin (product name “jER (registered trademark)” 828, manufactured by Japan Epoxy Resin Co., Ltd.) And 2.5 parts by mass of a curing agent (trade name “Tomide (registered trademark)” # 296, manufactured by Fuji Kasei Kogyo Co., Ltd.) in a mixed solvent of 300 parts by mass of chloroform and 100 parts by mass of methanol, A homogeneous solution was obtained. Next, the obtained uniform solution was atomized using a spray gun for coating, well stirred, and sprayed toward the liquid surface of 3000 parts by mass of n-hexane to precipitate a solute. The precipitated solid was separated by filtration, washed well with n-hexane, and then vacuum-dried at a temperature of 100 ° C. for 24 hours to obtain epoxy-modified nylon particles A (median diameter: 12.5 μm).
“Orgasol (registered trademark)” 1002D (manufactured by Arkema) (median diameter: 20 μm).

(1) Fracture toughness test (K _Ic evaluation) method of thermosetting resin cured product After defoaming a thermosetting resin composition to be described later in vacuum, the thickness was measured with a 6 mm thick “Teflon (registered trademark)” spacer. It was cured for 2 hours at a temperature of 180 ° C. in a mold set to 6 mm to obtain a cured resin product having a thickness of 6 mm. This cured resin was cut at 12.7 × 150 mm to obtain a test piece. Using an Instron universal testing machine, test pieces were processed and tested according to ASTM D5045. The initial cracking was introduced into the test piece by applying a razor blade cooled to the liquid nitrogen temperature to the test piece and impacting the razor with a hammer. The fracture toughness of the cured resin here is evaluated by the critical stress strength in deformation mode 1 (opening type).

(2) Particle size measurement of particles ([C] [D] [E]) The particle size distribution was measured by a laser diffraction scattering method using LA-950 manufactured by HORIBA Co., Ltd. using a laser diffraction scattering method. The particle size at 5% and 50% (median diameter) in each volume% in the cumulative curve of the obtained particle size distribution was determined. The CV value (coefficient of variation) of the particle size was calculated by the following formula.
CV value (%) of particle size = (standard deviation of particle size / median diameter) × 100.

(3) Presence of particles ([C] [D] [E]) existing in a depth range of 20% in thickness of the prepreg The prepreg is sandwiched between two polytetrafluoroethylene resin plates having a smooth 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-shaped resin cured product. After curing, the film was cut from the direction perpendicular to the contact surface, and the cross-section was polished, then magnified 200 times or more with an optical microscope, and photographed so that the upper and lower surfaces of the prepreg were within the visual field. By the same operation, the distance between the polytetrafluoroethylene resin plates was measured at five locations in the horizontal direction of the cross-sectional photograph, and the average value (n = 5) was taken as the thickness of the prepreg.

  On both sides of the prepreg, two lines parallel to the surface of the prepreg were drawn from the surface of the prepreg at a depth of 20% of the thickness. Next, the total area of the particles ([C] [D] [E]) existing between the surface of the prepreg and the above line and the total area of the particles existing over the thickness of the prepreg are obtained, and the thickness of the prepreg The abundance ratio of particles existing in a range of 20% depth from the surface of the prepreg was calculated for 100% thickness. The total area of the particles ([C] [D]) was determined by cutting out the particle portion from the cross-sectional photograph and converting it from the mass. [B] When it is difficult to discriminate particles ([C] [D] [E]) dispersed in the epoxy resin composition after photography, the particles ([C] [D] [E]) are dyed. Means were used.

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

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

(6) Determination of contact between conductive particles [C] between carbon fiber [A] and each carbon fiber [A] The carbon fiber reinforced composite material produced in (5) After cutting the cross section perpendicular to the laminating direction so that the layers of the fiber layers can be observed, the cross section is polished and then magnified 200 times or more with a laser microscope (KEYENCE VK-9510). The photo was taken so that it was within the field of view. From the same operation, 100 locations where conductive particles exist were arbitrarily selected. Since the conductive particles have a high probability of being cut at a cross section having a particle size smaller than the median diameter, the conductive particles are regarded as the median diameter size, and the conductive particles of that size are in contact with the respective carbon fibers, or When crossing, they were judged to be in contact and judged to be in contact. As a criterion, among 100 conductive particles, the number of conductive particles contacting both the upper surface carbon fiber and the lower surface carbon fiber between the layers is 30 or more (30% or more). When the number was less than 3% (less than 3% and less than 30%), it was marked as x.

(7) Evaluation Method for Microcrack Resistance of Carbon Fiber Reinforced Composite Material A unidirectional prepreg is quasi-isotropically laminated with 16 plies in a [+ 45 ° / 0 ° / −45 ° / 90 °] _2S configuration to form an autoclave. Then, it was molded at a temperature of 180 ° C. for 2 hours under a pressure of 0.59 MPa at a heating rate of 1.5 ° C./min. The obtained carbon fiber reinforced composite material plate was cut into a size of 75 mm × 50 mm with a diamond cutter to obtain a test piece. The test piece was exposed to environmental conditions as shown in the following procedures a, b, and c using a commercially available constant temperature and humidity chamber and an environmental test machine.
a. The sample is exposed to an environment of 49 ° C. and 95% relative humidity for 12 hours using a commercially available thermostatic chamber.
b. After exposure, the sample is transferred to a commercially available environmental testing machine, and exposed to an environment of -54 ° C for 1 hour. Thereafter, the temperature is raised to 71 ° C. at a temperature rising rate of 10 ° C. ± 2 ° C./min. After the temperature rise, hold at 71 ° C. for 5 minutes ± 1 minute, lower the temperature to −54 ° C. at 10 ° C. ± 2 ° C./minute, and hold at −54 ° C. for 5 minutes ± 1 minute. A cycle in which the temperature is raised from -54 ° C to 71 ° C and lowered to -54 ° C is defined as one cycle, and this cycle is repeated 400 times.
c. The above-mentioned environmental exposure in the constant temperature and humidity chamber and the cycle in the environmental testing machine are defined as 1 block, and 8 blocks are repeated.

  Cut out a width of 25 mm from an area of ± 10 mm from the longitudinal center of the test piece exposed to the environment, polished the cut surface as an observation surface, and observed the observation surface at a magnification of 200 times using a commercially available microscope. The number of cracks that occurred was measured.

  The above test piece was cut out at a speed of 23 cm / min using a diamond cutter (in addition, when processing was performed at a speed of 50 cm / min or more, a large friction was generated between the test piece and the diamond cutter. (Since vibration occurs and the test piece may crack due to frictional load, a speed of 23 cm / min was adopted here).

Example 1
In a kneading apparatus, 70 parts by mass of ELM434 and 30 parts by mass of EPICLON 830 were blended with 10 parts by mass of PES5003P, and a thermoplastic resin (PES5003P) was dissolved in the epoxy resin. Thereafter, 20 parts by mass of DP5045 particles A and 1 part by mass of ICB-2020 are kneaded, and further 40 parts by mass of 4,4′-diaminodiphenylsulfone as a curing agent is kneaded to produce a thermosetting resin composition. did.

The obtained thermosetting resin composition was evaluated for K _Ic as described in (1) Fracture toughness test (K _Ic evaluation) method of thermosetting resin cured product. The results are shown in Table 1.

Moreover, the prepared thermosetting resin composition was apply | coated on the release paper using the knife coater, and ^two 52 g / m < ² > resin films were produced. Next, the T800S-24K-10E arranged in one direction in a sheet shape is overlapped with the two resin films prepared above from both sides of the carbon fiber, and impregnated with the resin by heating and pressing, and the T800S-24K-10E A unidirectional prepreg having a basis weight of 190 g / m ² and a mass fraction of a matrix resin of 35.4% was produced.

Using the obtained prepreg, (3) the presence rate of particles existing in the depth range of 20% thickness of the prepreg,
(4) Compression strength measurement after impact of carbon fiber reinforced composite material, (5) Conductivity measurement of carbon fiber reinforced composite material, (6) Determination of contact between conductive particles between carbon fiber layers and each carbon fiber And (7) the carbon fiber reinforced composite material was evaluated as described in the evaluation of the microcrack resistance of the carbon fiber reinforced composite material. The results are shown in Table 1.

(Examples 2-35, Comparative Examples 1-6)
Thermosetting in the same manner as in Example 1 except that the types and blending amounts of carbon fiber, thermosetting resin composition, rubber particles, thermoplastic resin particles, and conductive particles were changed as shown in Tables 1 to 5. Resin composition and prepreg were prepared. In addition, when using the thermoplastic resin particles together with the rubber particles, they were put into the kneading apparatus at the same timing as the rubber particles. When using the thermoplastic resin particles alone without using the rubber particles, the thermoplastic resin particles were put into the kneading apparatus at the same timing instead of the rubber particles.
_KIc was evaluated using the produced thermosetting resin composition. In addition, using the produced unidirectional prepreg, the abundance ratio of particles existing within a depth range of 20% of the thickness of the prepreg, the compressive strength after impact of the carbon fiber reinforced composite material, the conductivity, the conductivity between the layers of the carbon fibers. Determination of contact between the particles and each carbon fiber and evaluation of microcrack resistance were performed. The obtained results are summarized in Tables 1 to 5.

  Any of the carbon fiber reinforced composite materials of Examples 1 to 35 had good microcrack resistance, and also exhibited excellent post-impact compressive strength and conductivity.

  On the other hand, Comparative Examples 1 and 6 are examples containing no conductive particles, and it was found that the conductivity of the carbon fiber reinforced composite material was low.

  The comparative example 2 is an example which does not contain rubber particles, and the micro crack resistance of the carbon fiber reinforced composite material was not sufficiently developed.

  Comparative Examples 3 to 5 are systems in which the toughness of the thermosetting resin cured product is insufficient, and it was found that the obtained carbon fiber reinforced composite material has poor microcrack resistance.

  According to the present invention, since a carbon fiber reinforced composite material having excellent mechanical properties and conductivity can be obtained, an aircraft structural member, a windmill blade, an automobile outer plate, an IC tray, a casing of a notebook computer, etc. It can be widely used for computer applications and is useful.

DESCRIPTION OF SYMBOLS 1 Rubber particle 2 Particle layer 3 Carbon fiber layer 4 Conductive particle 5 Carbon fiber 6 Thermosetting resin

Claims (20)

A carbon fiber [A], a thermosetting resin [B], a conductive particle [C], and a prepreg satisfying at least one of the following (1) and (2), wherein the thermosetting resin [B], Thermosetting resin composition comprising conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D] and thermoplastic resin particles [ The cured product obtained by curing the thermosetting resin composition comprising E] at 180 ° C. for 2 hours has a K _IC of 0.8 to 2.0 MPa · m ^1/2 , and conductive particles [C], rubber In each of the particles [D] and the thermoplastic resin particles [E], 90 to 100% by mass of the total amount is in the thickness direction of the prepreg from the respective main surfaces of the prepreg to the thickness of the prepreg. The rubber particles are distributed within a depth of 20%. D], or the particle diameter of the rubber particle [D] and the particle diameter of the thermoplastic resin particle [E] that are not smaller are the median diameters of the conductive particles [ C] rather small equal to or than the median diameter of particle size of, when the rubber particle [D] is in the case of measuring the particle size distribution by laser diffraction scattering method, of obtaining the cumulative curve of the total volume as 100%, A prepreg having a particle size of 1 to 5 μm with a cumulative curve of 5% .
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E]. A carbon fiber [A], a thermosetting resin [B], a conductive particle [C], and a prepreg satisfying at least one of the following (1) and (2), wherein the thermosetting resin [B], Thermosetting resin composition comprising conductive particles [C] and rubber particles [D], or thermosetting resin [B], conductive particles [C], rubber particles [D], and thermoplastic resin particles The cured product obtained by curing the thermosetting resin composition comprising [E] at a temperature of 180 ° C. for 2 hours has a K _IC of 0.8 to 2.0 MPa · m ^1/2 , and conductive particles [C], In each of the rubber particles [D] and the thermoplastic resin particles [E], 90 to 100% by mass of the total amount is from the main surface of one side of the prepreg to the thickness of the prepreg in the thickness direction of the prepreg. The rubber particles [D] are distributed in a range up to 20% depth. The particle diameter or the particle diameter of the rubber particle [D] and the particle diameter of the thermoplastic resin particle [E], which is not smaller, is the median diameter of the conductive particle [C]. same or rather smaller than the median diameter of particle size, rubber particle [D] is in the case of measuring the particle size distribution by laser diffraction scattering method, when calculated cumulative curve of the total volume as 100%, the cumulative curve A prepreg having a particle diameter of 1 to 5 μm with a 5% .
(1) Contains rubber particles [D].
(2) Including rubber particles [D] and thermoplastic resin particles [E]. The particle diameter of the rubber particle [D] or the particle diameter of the rubber particle [D] and the particle diameter of the thermoplastic resin particle [E] which is not smaller is 1 to 30 μm. The prepreg according to claim 1 or 2. The prepreg according to any one of claims 1 to 3 , wherein the coefficient of variation of the particle size of the conductive particles [C] is 10% or less, and the coefficient of variation of the particle size of the rubber particles [D] is 40% or more. The prepreg according to any one of claims 1 to 4 , wherein the rubber particles [D] are crosslinked rubber particles. Any of Claims 1-5 whose mass ratio represented by [the compounding quantity (mass part) of rubber particle [D]] / [the compounding quantity (mass part) of electroconductive particle [C]] is 1-1000. The prepreg according to crab. The mass ratio represented by [total amount (parts by mass) of rubber particles [D] and thermoplastic resin particles [E]] / [weight of conductive particles [C] (parts by mass)] is 1 to 1. The prepreg according to any one of claims 1 to 6 , which is 1000. The thermosetting resin [B] includes at least one epoxy resin selected from a tetraglycidylamine type epoxy resin, a bisphenol type epoxy resin, a glycidylaniline type epoxy resin, an aminophenol type epoxy resin, and a novolac type epoxy resin. Item 8. The prepreg according to any one of Items 1 to 7 . The prepreg according to claim 8 , wherein the tetraglycidylamine type epoxy resin is tetraglycidyldiaminodiphenylmethane. The prepreg according to any one of claims 1 to 9 , wherein 35 parts by mass or more of tetraglycidyldiaminodiphenylmethane is contained in 100 parts by mass of the thermosetting resin [B]. The average epoxy equivalent weight of tetraglycidyldiaminodiphenylmethane is 100 to 115 g / eq. The prepreg according to claim 9 or 10 , wherein The prepreg according to any one of claims 1 to 11 , wherein the thermosetting resin [B] contains a thermoplastic resin [F] dissolved in the thermosetting resin [B]. The prepreg according to claim 12 , wherein the thermoplastic resin [F] is polyethersulfone. The prepreg according to claim 13 , wherein the polyethersulfone has an average molecular weight of 15,000 to 30,000 g / mol. The prepreg according to claim 13 or 14 , wherein 12 to 25 parts by mass of polyethersulfone is contained in 100 parts by mass of the thermosetting resin [B]. The conductive particle [C] is at least one selected from the group consisting of carbon particles, and composite particles having a core particle of an inorganic material or an organic material and a conductive layer covering the core particle. The prepreg according to any one of to 15 . The prepreg according to claim 16 , wherein the conductive particles [C] are carbon particles. When the carbon fiber reinforced composite material is obtained by curing at 180 ° C. for 2 hours, 30% or more of the conductive particles [C] are contained between two adjacent prepregs, and The prepreg according to any one of claims 1 to 17 , wherein the prepreg is configured to come into contact with both of the two carbon fibers [A] constituting the prepreg. When a carbon fiber reinforced composite material was obtained by curing at a temperature of 180 ° C. for 2 hours, the temperature upper limit value was 71 ° C., the temperature lower limit value was −54 ° C., the holding time at each temperature was 3 minutes, and the temperature raising / lowering rate was 1 minute The prepreg according to any one of claims 1 to 18 , wherein the number of microcracks at the time of 3200 cycles of a thermal cycle test at 10 ° C is 10 or less. Carbon fiber reinforcement obtained by a method comprising the step of heating and pressurizing a laminate comprising at least two prepregs according to any one of claims 1 to 19 , wherein at least two of the prepregs are adjacent to each other. Composite material.

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