Prepreg and carbon fiber-reinforced composite material

The present invention relates to a prepreg and a carbon fiber reinforced composite material having both excellent impact resistance and conductivity.

Carbon fiber reinforced composite materials are useful because they are excellent in strength, rigidity, conductivity, etc., and computers such as aircraft structural members, windmill blades, automobile outer panels, IC trays, and laptop housings. It is widely used for various purposes, and its demand is increasing year by year.

The carbon fiber reinforced composite material is generally a non-uniform material formed by molding a prepreg containing carbon fiber, which is a reinforcing fiber, and a matrix resin as essential components. Therefore, the physical properties in the arrangement direction of the reinforcing fibers and other directions There is a big difference in the physical properties of. For example, the impact resistance indicated by the resistance to a falling weight impact is governed by the delamination strength quantified by the plate edge delamination strength between layers, so simply improving the strength of the reinforcing fibers is a drastic improvement. It is known that it does not lead to. In particular, the carbon fiber reinforced composite material using the thermosetting resin as the matrix resin has a property of being easily broken by stress from other than the arrangement direction of the reinforcing fibers, reflecting the low toughness of the matrix resin. Therefore, various techniques have been proposed for the purpose of improving the physical characteristics of the composite material that can cope with the stress from other than the arrangement direction of the reinforcing fibers.

As one of them, a prepreg in which a resin layer in which resin particles are dispersed is provided in a surface region of the prepreg has been proposed. For example, a technique has been proposed for providing a high toughness composite material having good heat resistance by using a prepreg provided with a resin layer in which particles made of a thermoplastic resin such as nylon are dispersed in a surface region of the prepreg (Patent Documents). 1). Separately, a technique for developing a high degree of toughness in a composite material by combining a matrix resin whose toughness has been improved by adding a polysulfone oligomer and particles made of a thermosetting resin has been proposed (Patent Document 2). reference). However, such a technique imparts a high degree of impact resistance to the carbon fiber reinforced composite material, while forming a resin layer as an insulating layer between the layers. Therefore, among the conductivity which is one of the characteristics of the carbon fiber reinforced composite material, there is a drawback that the conductivity in the thickness direction is remarkably lowered, and the carbon fiber reinforced composite material has both excellent impact resistance and conductivity. It was difficult.

Further, as a method for improving the conductivity between layers, a method of blending metal particles in a matrix resin of a carbon fiber reinforced composite material (see Patent Document 3) and a method of blending carbon particles (see Patent Document 4) are available. However, in these documents, there is no mention of compatibility between high impact resistance and conductivity.

<p><patcit num="1"><text>U.S. Pat. No. 5,028,478</text></patcit><patcit num="2"><text>Japanese Patent Application Laid-Open No. 3-26750</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 6-344519</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 8-34864</text></patcit></p>

<p> Therefore, an object of the present invention is to provide a prepreg and a carbon fiber reinforced composite material having both excellent impact resistance and conductivity in the thickness direction.</p>

<p> The prepreg of the present invention has the following configuration in order to achieve the above object. That is, a prepreg containing [A] carbon fiber and [B] thermosetting resin and satisfying at least one of the following (1) and (2). (1) Containing [C] thermoplastic resin particles or fibers and [D] conductive particles or fibers, [[C] compounding amount (parts by weight)] / [[D] compounding amount (parts by weight) )] The weight ratio is 1 to 1000. (2) [E] The core or core of the thermoplastic resin contains conductive particles or fibers coated with a conductive substance.</p><p> In addition, the carbon fiber reinforced composite material of the present invention has the following constitution in order to achieve the above object. That is, a carbon fiber reinforced composite material containing [A] carbon fiber and [B] thermosetting resin and satisfying at least one of the following (1) and (2). (1) Containing [C] thermoplastic resin particles or fibers and [D] conductive particles or fibers, [[C] compounding amount (parts by weight)] / [[D] compounding amount (parts by weight) )] The weight ratio is 1 to 1000. (2) [E] The core or core of the thermoplastic resin contains conductive particles or fibers coated with a conductive substance.</p>

<p> According to the present invention, it is possible to obtain a carbon fiber reinforced composite material having both excellent impact resistance and conductivity. In the prior art, when the impact resistance is high, the conductivity is low, and when the impact resistance is high, only a carbon fiber reinforced composite material having inferior impact resistance can be obtained. It has become possible to provide a carbon fiber reinforced composite material that simultaneously satisfies the above conditions.</p>

<figref num="1">This is an example of a cross-sectional view of a typical prepreg.</figref><figref num="2">It is a graph which showed the relationship between the post-impact compression strength and the volume specific resistance with respect to the weight ratio indicated by [[C] compounding amount (part by weight)] / [[D] compounding amount (part by weight)].</figref>

As a result of diligently studying the conductivity mechanism in the thickness direction of the carbon fiber reinforced composite material composed of carbon fiber and thermosetting resin, the present inventors imparted a high degree of impact resistance to the laminated interlayer portion while providing an insulating layer between the layers. In addition to the thermoplastic resin particles or fibers from which the resulting resin layer will be formed, the conductive particles or fibers are further arranged at a specific weight ratio, or the core or core of the thermoplastic resin is placed between the laminated layers. By arranging conductive particles or fibers coated with a conductive material, the carbon fibers have a high degree of impact resistance and conductivity without surprisingly reducing the carbon fiber content. He found that a reinforced composite material could be obtained, and came up with a prepreg that could obtain such a carbon fiber reinforced composite material.

The prepreg is a molded intermediate base material in which reinforcing fibers are impregnated with a matrix resin. In the present invention, carbon fibers are used as the reinforcing fibers 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 by curing the prepreg single layer. In the carbon fiber reinforced composite material obtained by laminating and curing a plurality of prepregs, the surface portion of the prepreg is the laminated interlayer portion of the carbon fiber reinforced composite material, and the inside of the prepreg is the inside of the laminated layer of the carbon fiber reinforced composite material. Become.

The prepreg of the present invention is a prepreg containing [A] carbon fiber and [B] thermosetting resin, and satisfying at least one of the following (1) and (2). (1) Containing [C] thermoplastic resin particles or fibers and [D] conductive particles or fibers, [[C] compounding amount (parts by weight)] / [[D] compounding amount (parts by weight) )] The weight ratio is 1 to 1000. (2) [E] The core or core of the thermoplastic resin contains conductive particles or fibers coated with a conductive substance.

In the embodiment satisfying (1), the prepreg and the carbon fiber reinforced composite material obtained from the prepreg are composed of [A] carbon fiber, [B] thermosetting resin, [C] thermoplastic resin particles or fibers, and [D. ] Contains conductive particles or fibers. In this embodiment, it is preferable to use thermoplastic resin particles as [C] and conductive particles as [D]. When both [C] and [D] are in the particle form, the flow characteristics of the thermosetting resin are better and carbon is better than in the case where either one is in the fiber form or both are in the fiber form. This is because the impregnation property into the fiber is excellent. Further, by using the thermoplastic resin particles and the conductive particles in combination, delamination caused by the local impact during the drop impact (or local impact) on the carbon fiber reinforced composite material is reduced. Therefore, when stress is applied to the carbon fiber reinforced composite material after such impact, there are few delamination portions caused by the local impact, which is the starting point of fracture due to stress concentration, and conductive particles are laminated. Since the contact probability with the carbon fibers in the layer is high and the conductive path is easily formed, a carbon fiber reinforced composite material exhibiting high impact resistance and conductivity can be obtained.

Further, in the embodiment satisfying (2), in the prepreg and the carbon fiber reinforced composite material obtained from the prepreg, the nuclei of [A] carbon fiber, [B] thermosetting resin, and [E] thermoplastic resin are conductive. Includes conductive particles coated with a substance or conductive fibers in which a core of a thermoplastic resin is coated with a conductive substance. Here, [E] is the conductive particles of the above [D] in which the core of the thermoplastic resin is coated with a conductive substance or the core of the thermoplastic resin is coated with a conductive substance. It has a specific aspect of a fiber. By using [E] having such a specific aspect, the effect obtained by the combined use of [C] and [D] can be obtained only with [E].

Compared to the aspect satisfying (2), the aspect satisfying (1) is due to the effect of the excellent toughness of the particles or fibers of the [D] thermoplastic resin in the laminated interlayer part, and the weight impact on the carbon fiber reinforced composite material. At the time, it is excellent in that it has high delamination strength and higher impact resistance. On the other hand, the mode satisfying (2) is superior to the mode satisfying (1) in that it can be expected to reduce the cost and improve the productivity because the number of components used is small.

The [A] carbon fiber used in the present invention is preferably a carbon fiber having a tensile elastic modulus of at least 260 GPa because it exhibits higher conductivity, but from the viewpoint of compatibility with impact resistance, it is preferable. It is preferably a carbon fiber having a tensile elastic modulus of at most 440 GPa. From this point of view, a tensile elastic modulus in the range of 280 to 400 GPa is particularly preferable because both conductivity and impact resistance can be achieved at a high level.

In addition, from the viewpoint of impact resistance, a composite material having excellent impact resistance, high rigidity and mechanical strength can be obtained, so that the tensile strength is 4.4 to 6.5 GPa and the tensile elongation is 1.7 to 1. It is preferably 2.3% high-strength, high-elongation carbon fiber. Therefore, from the viewpoint 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 the most suitable. Tensile modulus, tensile strength and tensile elongation can be measured by the strand tensile test described in JIS R 7601-1986.

The [B] thermosetting resin used in the present invention is not particularly limited as long as it is a resin in which a cross-linking reaction proceeds by heat to form a three-dimensional cross-linked structure at least partially. Examples of such thermosetting resins include unsaturated polyester resins, vinyl ester resins, epoxy resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimide resins, and modified products thereof and two or more kinds thereof. Blended resins and the like can also be used. Further, these thermosetting resins may be self-curing by heating, or may be blended with a curing agent, a curing accelerator, or the like.

Among these thermosetting resins, an epoxy resin having an excellent balance of heat resistance, mechanical properties and adhesiveness with carbon fibers is preferably used. In particular, an epoxy resin using amines, phenols, or a compound having a carbon-carbon double bond as a precursor is preferably used. Specific examples of the glycidylamine type epoxy resin using amines as a precursor include various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol and triglycidylaminocresol. Tetraglycidyl diaminodiphenylmethane is preferable as a resin for composite materials as an aircraft structural material because it has excellent heat resistance.

Further, as the thermosetting resin, a glycidyl ether type epoxy resin using phenol as a precursor is also preferably used. Examples of such an epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin and resorcinol type epoxy resin.

Liquid bisphenol A type epoxy resin, bisphenol F type epoxy resin and resorcinol type epoxy resin are preferably used in combination with other epoxy resins because of their low viscosity.

In addition, the bisphenol A type epoxy resin that is solid at room temperature (about 25 ° C) gives a structure with a lower crosslink density in the cured resin than the bisphenol A type epoxy resin that is liquid at room temperature (about 25 ° C). , The cured resin has lower heat resistance, but higher toughness, so it can be combined with glycidylamine type epoxy resin, liquid bisphenol A type epoxy resin, or bisphenol F type epoxy resin. It is preferably used.

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

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

These epoxy resins may be used alone or in combination as appropriate. It is preferable to use a mixture of at least a bifunctional epoxy resin and a trifunctional or higher functional epoxy resin because the resin can have both fluidity and heat resistance after curing. In particular, the combination of the glycidyl amine type epoxy and the glycidyl ether type epoxy makes it possible to achieve both heat resistance, water resistance and processability. Further, 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 tack property and drape property of the prepreg appropriate.

Since the phenol novolac type epoxy resin and the cresol novolac type epoxy resin have high heat resistance and low water absorption rate, they 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, it is possible to adjust the tackiness and drape property of the prepreg while increasing the heat resistance and water resistance.

As the curing agent for the epoxy resin, any compound having an active group capable of reacting with the epoxy group can be used. As the curing agent, a compound having an amino group, an acid anhydride group and an azide group is suitable. More specifically, as the curing agent, for example, dicyandiamide, various isomers of diaminodiphenylmethane and diaminodiphenylsulfone, aminobenzoic acid esters, various acid anhydrides, phenol novolac resin, cresol novolac resin, polyphenol compound, imidazole derivative. Lewis like carboxylic acid anhydrides such as aliphatic amines, tetramethylguanidine, thiourea addition amines, methylhexahydrophthalic anhydrides, carboxylic acid hydrazides, carboxylic acid amides, polymercaptans and boron trifluoride ethylamine complexes. Acid complexes and the like can be mentioned. These curing agents may be used alone or in combination.

By using an aromatic diamine as a curing agent, a cured resin having good heat resistance can be obtained. In particular, various isomers of diaminodiphenyl sulfone are most suitable for obtaining a cured resin having good heat resistance. It is preferable to add the aromatic diamine so that the amount of the curing agent added is stoichiometrically equivalent, but in some cases, for example, by using an equivalent ratio of about 0.7 to 0.8, a cured resin having a high elastic modulus can be obtained. can get.

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

Further, these epoxy resins and a curing agent, or a product obtained by pre-reacting a part of them can be blended in the composition. This method may be effective in adjusting the viscosity and improving the storage stability.

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

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

When a mixture of a thermosetting resin and a thermoplastic resin is used, better results are obtained than when they are used alone. The brittleness of the thermosetting resin is covered by the toughness of the thermoplastic resin, and the molding difficulty of the thermoplastic resin is covered by the thermosetting resin, resulting in a well-balanced base resin. The ratio (part by weight) of the thermosetting resin and the thermoplastic resin to be used is preferably in the range of 100: 2 to 100: 50, and more preferably in the range of 100: 5 to 100: 35 in terms of balance.

It is also preferable to mix the thermosetting resin with a conductive filler for the purpose of increasing the contact probability between the carbon fibers and improving the conductivity of the carbon fiber reinforced composite material. Examples of such conductive fillers include carbon black, carbon nanotubes, vapor-grown carbon fibers (VGCF), fullerene, and metal nanoparticles, which may be used alone or in combination. Of these, inexpensive and highly effective carbon black is preferably used, and examples of such carbon black include furnace black, acetylene black, thermal black, channel black, and Ketjen black, and two or more of these can be used. Blended carbon black is also preferably used. The conductive filler referred to here is based on the average diameter of [D] conductive particles or fibers and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance. Also refers to conductive particles or fibers with a small mean diameter (usually 0.1 times or less).

In the embodiment satisfying (1) of the present invention, since the particles or fibers of [C] thermoplastic resin are used as essential components, excellent impact resistance can be realized. As the material of the particles or fibers of the [C] thermoplastic resin used in the present invention, the same thermoplastic resin as the various thermoplastic resins exemplified above is used as the thermoplastic resin mixed and dissolved in the thermosetting resin. be able to. Among them, polyamide is most preferable because it has excellent toughness and can greatly improve impact resistance. Among the polyamides, nylon 12, nylon 11 and nylon 6/12 copolymers have particularly good adhesive strength with [B] thermosetting resin, and therefore, between layers of carbon fiber reinforced composite material at the time of impact of falling weight. It is preferable because it has high peel strength and a high impact resistance improving effect.

When the thermoplastic resin particles are used as [C], the shape of the thermoplastic resin particles may be spherical, non-spherical, porous, needle-shaped, whisker-shaped, or flake-shaped, but the spherical shape is more thermal. Since it does not deteriorate the flow characteristics of the curable resin, it has excellent impregnation properties into carbon fibers, and when a weight impact (or local impact) is applied to a carbon fiber reinforced composite material, delamination caused by local impact is more likely to occur. Since it is reduced, it is high because there are fewer delamination portions caused by the local impact, which is the starting point of failure due to stress concentration when stress is applied to the carbon fiber reinforced composite material after such impact. It is preferable because a carbon fiber reinforced composite material exhibiting impact resistance can be obtained.

When a thermoplastic resin fiber is used as [C], both short fibers and long fibers can be used as the shape of the thermoplastic resin fiber. In the case of short fibers, as shown in Japanese Patent Application Laid-Open No. 2-69566, it is possible to use short fibers in the same manner as particles, or to process them into mats. In the case of long fibers, a method of arranging the long fibers parallel to the surface of the prepreg as shown in JP-A-4-292634 and a method of arranging the long fibers randomly as shown in International Publication No. 94016003 are possible. Further, it can be processed into a woven fabric as shown in JP-A-2-32843, a non-woven fabric as shown in International Publication No. 94016003, or a sheet-like base material such as a knitted fabric. Further, a method in which short fiber chips, chopped strands, milled fibers, or short fibers are used as spun yarns and processed into a woven fabric or knitted fabric in which they are arranged in parallel or randomly can also be used.

When conductive particles are used as [D] in the present invention, the conductive particles may be particles that behave as electrically good conductors, and are not limited to those consisting only of conductors. Preferably the volume intrinsic resistance is 10-10^-9Ωcm, more preferably 1-10^-9Ωcm, more preferably 10^-1~10^-9It is a particle that is Ω. If the volume specific resistance 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 metal particles, polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaften particles, polyethylenedioxythiophene particles, carbon particles, and nuclei of inorganic materials. Can be used as particles obtained by coating the particles with a conductive material, or particles having a core of an organic material coated with a conductive material. 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 particularly preferable because they exhibit high conductivity and stability. Used.

In particular, carbon fibers obtained by using a thermoplastic resin as an organic material and using particles in which the core of the thermoplastic resin is coated with a conductive substance, as in the embodiment of the present invention (2) described later, are used. It is preferable because even better impact resistance can be realized in the reinforced composite material.

When a conductive fiber is used as [D] in the present invention, the conductive fiber may be any fiber that behaves as an electrically good conductor, and is not limited to a conductor only. Preferably the volume intrinsic resistance is 10-10^-9Ωcm, more preferably 1-10^-9Ωcm, more preferably 10^-1~10^-9It is a fiber that is Ω. If the volume specific resistance is too high, sufficient conductivity may not be obtained in the carbon fiber reinforced composite material. As the conductive fiber, for example, a metal fiber, a carbon fiber, a fiber in which the core of an inorganic material is coated with a conductive substance, a fiber in which a core of an organic material is coated with a conductive substance, or the like can be used. .. In particular, carbon fibers obtained by using a thermoplastic resin as an organic material and adopting a fiber in which the core of the thermoplastic resin is coated with a conductive substance, as in the embodiment of the present invention (2) described later. Even better impact resistance can be achieved with reinforced composite materials.

The volume specific resistance referred to here is calculated from the thickness and resistance value of a sample set in a cylindrical cell having four probe electrodes and a pressure of 60 MPa is applied to the sample. Let it be the volume specific resistance.

In the type of [D] conductive particles or fibers coated with a conductive substance, the conductive particles or fibers are composed of an inorganic material or an organic material which is a core or a core and a conductive layer made of a conductive substance. It is configured, and if necessary, an adhesive layer as described later may be provided between the core or core and the conductive layer.

In the type of [D] conductive particles or fibers coated with a conductive substance, examples of the inorganic material used as a core or a core include inorganic oxides, inorganic organic composites, and carbon.

Examples of the inorganic oxide include a single inorganic oxide such as silica, alumina, zirconia, titania, silica-alumina, and silica-zirconia, and two or more composite inorganic oxides.

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

Further, as carbon, crystalline carbon and amorphous carbon are preferably used. Examples of amorphous carbon include "Belpearl" (registered trademark) C-600, C-800, C-2000 (manufactured by Kanebo Co., Ltd.), "NICABEADS" (registered trademark) ICB, PC, MC (Nippon Carbon). (Made by Co., Ltd.), etc.

In the type of [D] conductive particles or fibers coated with a conductive substance, when an organic material is used as the core or core, the organic material used as the core or core is an unsaturated polyester resin, vinyl ester resin, or the like. Thermocurable resins such as epoxy resin, benzoxazine resin, phenol resin, urea resin, melamine resin and polyimide resin, polyamide resin, phenol resin, amino resin, acrylic resin, ethylene-vinyl acetate resin, polyester resin, urea resin, melamine Examples thereof include resins, alkyd resins, polyimide resins, urethane resins, and thermoplastic resins such as divinylbenzene resins. Further, two or more kinds of the materials listed here may be used in combination. Of these, acrylic resins and divinylbenzene resins having excellent heat resistance, and polyamide resins having excellent impact resistance are preferably used.

In the aspect satisfying (2) of the present invention, since conductive particles or fibers in which the core or core of the [E] thermoplastic resin is coated with a conductive substance are used as an essential component, the [C] thermoplastic resin is used. High impact resistance and conductivity can be exhibited in the carbon fiber reinforced composite material without adding the particles or fibers of the above. The thermoplastic resin used as the material for the core or core of the conductive particles or fibers in [E] used in the present invention is the various types of heat exemplified above as the thermoplastic resin used by mixing and dissolving in the thermosetting resin. The same as the plastic resin can be used. Above all, the strain energy release rate (G)_1c) Is 1500 ~ 50000J / m²It is preferable to use the thermoplastic resin of the above as a material for the core or the core. More preferably, 3000-40000 J / m², More preferably 4000 ~ 30000J / m²Is. Strain energy release rate (G_1cIf) 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 be reduced. As such a thermoplastic resin, for example, polyamide, polyamideimide, polyethersulfone, polyetherimide and the like are preferably used, and polyamide is particularly preferable. Among the polyamides, nylon 12, nylon 11 and nylon 6/12 copolymers are preferably used. G_1cThe evaluation of is performed by the compact tension method or the double tension method specified in ASTM D 5045-96 using a resin plate formed of a thermoplastic resin which is the material of the core or core of [E].

When conductive particles in which the core of the thermoplastic resin is coated with a conductive substance are used as [E], the shape of the core of the thermoplastic resin particles may be spherical, non-spherical, porous, needle-shaped, or whisker-shaped. , Or flakes, but spherical ones are more excellent in impregnation with carbon fibers because they do not deteriorate the flow characteristics of the thermosetting resin. In addition, when a weight impact (or local impact) is applied to the carbon fiber reinforced composite material, delamination caused by the local impact is further reduced, so that the carbon fiber reinforced composite material is stressed after the impact. In some cases, the delamination portion generated due to the local impact, which is the starting point of fracture due to stress concentration, is reduced, the contact probability with the carbon fibers in the laminated layer is high, and a conductive path is easily formed. Therefore, it is preferable in that a carbon fiber reinforced composite material exhibiting high impact resistance and conductivity can be obtained.

When a conductive fiber in which the core of the thermoplastic resin is coated with a conductive substance is used as [E], both short fibers and long fibers can be used as the shape of the core of the thermoplastic resin fiber.

In the case of short fibers, as shown in Japanese Patent Application Laid-Open No. 2-69566, it is possible to use short fibers in the same manner as particles, or to process them into mats. In the case of long fibers, a method of arranging the long fibers parallel to the surface of the prepreg as shown in JP-A-4-292634 and a method of arranging the long fibers randomly as shown in International Publication No. 94016003 are possible. Further, it can be processed into a woven fabric as shown in Japanese Patent Application Laid-Open No. 2-32843, a non-woven fabric as shown in International Publication No. 94016003, or a sheet-like base material such as a knitted fabric. Further, a method in which short fiber chips, chopped strands, milled fibers, or short fibers are used as spun yarns and processed into a woven fabric or knitted fabric in which they are arranged in parallel or randomly can also be used.

When coating the core of a thermoplastic resin fiber with a conductive substance, a method of coating the core of the thermoplastic resin fiber with the conductive substance after processing the core into the above shape, or coating the core of the thermoplastic resin fiber with the conductive substance. After that, there is a method of processing into the above shape. Both short fibers, long fibers, chopped strands and milled fibers are preferably used. For woven fabrics, knitted fabrics, and non-woven fabrics, a method in which a core of a thermoplastic resin fiber is coated with a conductive substance and then processed into the above-mentioned shape is preferably used. In the case of woven fabrics, knitted fabrics, and non-woven fabrics, if the core of the thermoplastic resin particles is processed into such a shape and then coated with a conductive substance, coating unevenness may occur and the conductivity of [E] may decrease, which is preferably used. Because it cannot be done.

[E] In conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance, the conductive substance covering the core or core may be metal or carbon. Further, in [E], a conductive layer is formed of the conductive substance on the surface of the core or core of the thermoplastic resin, and the conductive layer is in the form of a continuous film of metal or carbon. Alternatively, it may be an aggregate of fibrous or particulate conductive substances such as conductive fibers, carbon black, and metal fine particles. Further, an adhesive layer as described later may be provided between the thermoplastic resin which is the core or the core and the conductive layer.

A conductive layer in [D] conductive particles or fibers of the type coated with a conductive substance, and [E] conductive particles or fibers in which the core or core of a thermoplastic resin is coated with a conductive substance. The conductive substance constituting the above may be any substance that behaves as an electrically good conductor, and is not limited to a substance composed of only a conductor. Preferably the volume intrinsic resistance is 10-10^-9Ωcm, more preferably 1-10^-9Ωcm, more preferably 10^-1~10^-9It is a substance that is Ω. If the volume specific resistance is too high, sufficient conductivity may not be obtained in the carbon fiber reinforced composite material. For example, carbon or metal may be mentioned, and the conductive layer may be a continuous film of carbon or metal, or may be an aggregate of fibrous or particulate conductive substances.

When carbon is used as the conductive substance, carbon black such as channel black, thermal black, furnace black, and Ketjen black, hollow carbon fiber, and the like are preferably used. Among them, hollow carbon fiber is preferably used, and its outer shape is preferably 0.1 to 1000 nm, and more preferably 1 to 100 nm. 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 its surface. At that time, the total number of graphite layers to be composed is preferably 1 to 100 layers, more preferably 1 to 10 layers, further preferably 1 to 4 layers, and particularly preferably 1 to 2 layers. belongs to.

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, and 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 decrease. Here, the standard electrode potential is the electrode potential when the metal is immersed in a solution containing the metal ions, and the standard hydrogen electrode (platinum immersed in a specified HCl solution in contact with hydrogen gas at 1 atm). It is represented by the difference from the potential. For example, Ti: -1.74V, Ni: -0.26V, Cu: 0.34V, Ag: 0.80V, Au: 1.52V.

When the above metal is used, it is preferably the metal used by plating. Preferred metals include platinum, gold, silver, copper, tin, nickel, titanium, cobalt, zinc, iron, chromium, and aluminum because they can prevent metal corrosion due to a potential difference from carbon fibers. Platinum, gold, silver, copper, tin, nickel, or titanium is particularly preferably used because it exhibits high conductivity and stability with a volume specific resistance of 10 to 10-9 Ωcm. These metals may be used alone or as an alloy containing these metals as a main component.

Wet plating and dry plating are preferably used as a method for performing metal plating using the above-mentioned metal. As the wet plating, methods such as electroless plating, replacement plating, and electroplating can be adopted, but since it is possible to plate non-conductors, the method by electroless plating is preferably used. Be done. As the dry plating, methods such as vacuum vapor deposition, plasma CVD (chemical vapor deposition), optical CVD, ion plating, and sputtering can be adopted, but since excellent adhesion can be obtained even at low temperatures, the method by sputtering can be adopted. Is preferably used.

Further, the metal plating may be a coating of a single metal or a coating of a plurality of layers composed of a plurality of metals. When metal plating is performed, it is preferable that a plating film having a layer made of gold, nickel, copper, or titanium on the outermost surface is formed. By using the above metal as the outermost surface, it is possible to reduce the connection resistance value and stabilize the surface. 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 substitution 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 the potential difference with the carbon fiber. An alloy containing the above as a main component, or tin oxide, indium oxide, indium tin oxide (ITO), or the like is preferably used. Among these, platinum, gold, silver, copper, tin, nickel, titanium or alloys containing these as main components are particularly preferably used because they exhibit high conductivity and stability. Here, the fine particles are larger than the average diameter of [D] conductive particles or fibers and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance. Particles with a small mean diameter (usually 0.1 times or less).

As a method of coating the core or the core with the above-mentioned metal fine particles, a mechanochemical bonding method is preferably used. Mechanochemical bonding is a method in which a plurality of different material particles are mechanically and chemically bonded at the molecular level to create strong nanobonds at the interface to create composite fine particles. In the present invention, metal fine particles are bonded to the core or core of an inorganic material or organic material, and the core or core is coated with the metal fine particles.

When metal fine particles are coated on the core of an inorganic material or an organic material (including a thermoplastic resin), the particle size of the metal fine particles is preferably 1/1000 to 1/10 times the average particle size of the core, and more. It is preferably 1/500 to 1/100 times. It may be difficult to produce metal fine particles having an excessively small particle size, and conversely, if the particle size of the metal fine particles is too large, coating unevenness may occur. Further, when the core of an inorganic material or an organic material is coated with metal fine particles, the particle size of the metal fine particles is preferably 1/1000 to 1/10 times the average fiber diameter of the core, and more preferably 1/500. It is ~ 1/100 times larger. It may be difficult to produce metal fine particles having an excessively small particle size, and conversely, if the particle size of the metal fine particles is too large, coating unevenness may occur.

In the type of [D] conductive particles or fibers coated with a conductive substance, and in the [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance, the core or fiber. The adhesive layer may or may not be present between the core and the conductive layer, but may be present if the core or the core and the conductive layer are easily peeled off. In this case, the main components of the adhesive layer 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 preferable, among them 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, epoxy resin and the like.

In conductive particles or fibers of type [D] conductive particles coated with a conductive substance, and [E] conductive particles or fibers in which the core or core of a thermoplastic resin is coated with a conductive substance, the conductive substance. For the conductive particles or fibers coated with, the volume ratio represented by [volume of core or core] / [volume of conductive layer] is preferably 0.1 to 500, more preferably 1 to 300. More preferably, it is preferable to use one having a value of 5 to 100. Not only does the weight of the obtained carbon fiber reinforced composite material increase if the volume ratio is less than 0.1, but it may not be uniformly dispersed during resin preparation, and conversely, if it exceeds 500, the obtained carbon fiber reinforced composite material may not be uniformly dispersed. In some cases, sufficient conductivity cannot be obtained.

Of the conductive particles or fibers used in the present invention ([D] conductive particles or fibers, and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance). The specific gravity is preferably 3.2 at the maximum. If the specific gravity of the conductive particles or fibers exceeds 3.2, not only the weight of the obtained carbon fiber reinforced composite material increases, but also it may not be uniformly dispersed during the resin formulation. From this point of view, the specific gravity of the conductive particles or fibers is preferably 0.8 to 2.2. If the specific gravity of the conductive particles or fibers is less than 0.8, it may not be uniformly dispersed during resin preparation.

When particles are used as [D] conductive particles or fibers and [E] conductive particles or fibers in which the core or core of a thermoplastic resin is coated with a conductive substance, the shape may be spherical or non-spherical. However, it may be porous, needle-shaped, whisker-shaped, or flake-shaped, but the spherical shape is superior in impregnation property with carbon fibers because it does not deteriorate the flow characteristics of the thermosetting resin. In addition, when a weight impact (or local impact) is applied to the carbon fiber reinforced composite material, delamination caused by the local impact is further reduced, so that the carbon fiber reinforced composite material is stressed after the impact. In some cases, the delamination portion generated due to the local impact, which is the starting point of fracture due to stress concentration, is reduced, the contact probability with the carbon fibers in the laminated layer is high, and a conductive path is easily formed. Therefore, it is preferable in that a carbon fiber reinforced composite material exhibiting high impact resistance and conductivity can be obtained.

When fibers are used as [D] conductive particles or fibers and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance, the shape is short fibers or long fibers. It can be used together with fibers. In the case of short fibers, as shown in Japanese Patent Application Laid-Open No. 2-69566, it is possible to use short fibers in the same manner as particles, or to process them into mats. In the case of long fibers, a method of arranging the long fibers parallel to the surface of the prepreg as shown in JP-A-4-292634 and a method of arranging the long fibers randomly as shown in International Publication No. 94016003 are possible. Further, it can be processed into a woven fabric as shown in Japanese Patent Application Laid-Open No. 2-32843, a non-woven fabric as shown in International Publication No. 94016003, or a sheet-like base material such as a knitted fabric. Further, a method in which short fiber chips, chopped strands, milled fibers, or short fibers are used as spun yarns and processed into a woven fabric or knitted fabric in which they are arranged in parallel or randomly can also be used.

In [D] conductive fibers of the type coated with a conductive substance and [E] conductive fibers in which the core of a thermoplastic resin fiber is coated with a conductive substance, the core of the material is a conductive substance. When coating with, a method of processing the core of the conductive fiber into the above shape and then coating the conductive material, or a method of coating the core of the conductive fiber with the conductive material and then processing into the above shape is possible. is there. Both methods are preferably used for short fibers, long fibers, chopped strands, milled fibers and the like. For woven fabrics, knitted fabrics, and non-woven fabrics, a method in which a conductive fiber core is coated with a conductive substance and then processed into the above shape is preferably used. The method of coating the conductive substance after processing the core of the conductive fiber into the above shape causes uneven coating, and the conductivity of the conductive fiber used as [D] and [E] is lowered. In some cases, it is not preferable.

In the embodiment (1) of the present invention (combined use of thermoplastic resin particles or fibers with conductive particles or fibers), [amount of thermoplastic resin particles or fibers blended (parts by weight)] / [conductive] The weight ratio represented by the compounding amount (parts by weight) of the sex particles or fibers is 1 to 1000, preferably 10 to 500, and more preferably 10 to 100. If the weight ratio is less than 1, sufficient impact resistance cannot be obtained in the obtained carbon fiber reinforced composite material, and if the weight ratio is larger than 1000, sufficient impact resistance cannot be obtained in the obtained carbon fiber reinforced composite material. This is because conductivity cannot be obtained.

In the embodiment (1) of the present invention (combined use of thermoplastic resin particles or fibers with conductive particles or fibers), [D] the average diameter of the conductive particles or fibers (average particle size or average fiber). The diameter) is the same as or larger than the average diameter (average particle size or average fiber diameter) of the particles or fibers of the [C] thermoplastic resin, and the average diameter is preferably 150 μm at the maximum. When the average diameter of [D] conductive particles or fibers is smaller than the average diameter of [C] thermoplastic resin particles or fibers, it is [D] conductive to the insulating [C] thermoplastic resin particles or fibers. The conductive particles or fibers are buried between the layers, and it is difficult to form a conductive path between the carbon fibers in the layer and the [D] conductive particles or fibers, which may not bring about a sufficient effect of improving conductivity.

Further, in the present invention, [C] thermoplastic resin particles or fibers, [D] conductive particles or fibers, and [E] conductive particles in which the core or core of the thermoplastic resin is coated with a conductive substance. Alternatively, the average diameter of the fibers is preferably at most 150 μm. When the average diameter exceeds 150 μm, the layers of the obtained composite material are made thicker than necessary when the arrangement of the reinforcing fibers is disturbed or the particle layer is formed near the surface of the prepreg as described later. Therefore, when it is formed into a composite material, its physical properties may be deteriorated. The average diameter is preferably 1 to 150 μm, more preferably 3 to 60 μm, and particularly preferably 5 to 30 μm. If the average diameter is too small, the particles may sneak between the fibers of the reinforcing fibers and may not be localized in the interlayer portion of the prepreg laminate, the effect of the presence of the particles may not be sufficiently obtained, and the impact resistance may be lowered. is there.

Here, the method for measuring the mean diameter will be described for each of the case where the object is a particle and the case where the object is a fiber.

Regarding the average particle size (mean particle size) of the particles, for example, the particles are magnified 1000 times or more with a microscope such as a scanning electron microscope, photographed, randomly selected particles, and the diameter of the circumscribing circle of the particles. Is the particle size, and can be obtained as the average value (n = 50) of the particle size. In addition, when determining the volume ratio represented by [volume of nucleus] / [volume of conductive layer] of conductive particles coated with a conductive substance, first, the average particle size of the nuclei of the conductive particles is calculated as described above. It is measured by the method, or the average diameter (average particle size) of the conductive particles is measured by the above method. After that, the cross section of the conductive particles coated with the conductive substance is magnified 10,000 times with a scanning microscope, photographed, the thickness of the conductive layer is measured (n = 10), and the average value is taken. calculate. Such measurements are performed on the above randomly selected conductive particles (n = 50). The average particle size of the core of the conductive particles and twice the average value of the thickness of the conductive layer are added to obtain the average particle size of the conductive particles (average particle size), or the average diameter of the conductive particles (average). The average particle size (average particle size) of the core of the conductive particle is obtained by subtracting twice the average value of the particle size) and the thickness of the conductive layer. Then, using the average diameter (average particle size) of the nuclei of the conductive particles and the average diameter (average particle size) of the conductive particles, the volume ratio expressed by [volume of the nucleus] / [volume of the conductive layer]. Can be calculated.

Regarding the average fiber diameter (average fiber diameter), for example, the fiber cross section is magnified 1000 times or more with a microscope such as a scanning electron microscope, and a photograph is taken. The diameter of the circle is taken as the fiber diameter, and it can be obtained as the average value (n = 50) of the fiber diameter. In addition, when determining the volume ratio represented by [volume of core] / [volume of conductive layer] of conductive fibers coated with a conductive substance, first, the average fiber diameter of the cores of conductive fibers is calculated as described above. Measure by the method, or measure the average diameter of conductive fibers (average fiber diameter) by the method. After that, the cross section of the conductive fiber coated with the conductive substance is magnified 10,000 times with a scanning microscope, photographed, the thickness of the conductive layer is measured (n = 10), and the average value is taken. calculate. Such measurements are performed on the above randomly selected conductive fibers (n = 50). The average diameter of the core of the conductive fiber (average fiber diameter) and twice the average value of the thickness of the conductive layer are added to obtain the average diameter of the conductive fiber (average fiber diameter), or the average fiber diameter of the conductive fiber. The average diameter of the core of the conductive fiber (average fiber diameter) is obtained by subtracting twice the average value of the average diameter (average fiber diameter) and the thickness of the conductive layer. Then, using the average diameter of the core of the conductive fiber (average fiber diameter) and the average diameter of the conductive fiber (average fiber), the volume ratio expressed by [volume of the core] / [volume of the conductive layer]. Can be calculated.

The prepreg according to the present invention preferably has a carbon fiber weight fraction of 40 to 90%, more preferably 50 to 80%. If the carbon fiber weight fraction is too low, the weight of the resulting composite will be excessive, which may undermine the advantages of the fiber reinforced composite with excellent specific strength and modulus, and the carbon fiber weight fraction is high. If it is too much, poor resin impregnation may occur, and the obtained composite material tends to have many voids, and its mechanical properties may be significantly deteriorated.

In the prepreg of the present invention, [C] thermoplastic particles or fibers, [D] conductive particles or fibers, and [E] conductive particles in which the core or core of the thermoplastic resin is coated with a conductive substance. Alternatively, it is preferable that all the fibers are localized on the surface portion of the prepreg. In other words, the particles or fiber-rich layers of [C], [D], and [E], that is, the particles of [C], [D], and [E] when the cross section thereof is observed. It is preferable that a layer (hereinafter, may be referred to as an interlayer formation layer) in which the state in which the fibers are localized can be clearly confirmed is formed on the surface portion of the prepreg. As a result, when the prepregs are laminated and the matrix resin is cured to form a carbon fiber reinforced composite material, the particles or fibers of [C], [D], and [E] are localized between the carbon fiber layers. The layers are formed, whereby the toughness between the carbon fiber layers is enhanced, and the particles or fibers of [D] and [E] contained in the interlayer forming layer can form a conductive path between the carbon fiber layers. Therefore, a high degree of impact resistance and conductivity can be exhibited in the obtained carbon fiber reinforced composite material.

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 has a thermosetting resin 6, a thermoplastic resin particle 3, and a conductive material between the carbon fiber 5 and the two carbon fiber layers 1 composed of the thermosetting resin 6. It has an interlayer forming layer 2 containing particles 4. The formation of the interlayer formation layer 2 enhances the toughness between the carbon fiber layers, and the conductive particles 4 contained in the interlayer formation layer 2 can form a conductive path between the carbon fiber layers, so that the obtained carbon fiber reinforcement can be obtained. High impact resistance and conductivity are exhibited in the composite material.

From this point of view, the cambium is present in a depth range of 20%, more preferably 10%, from at least one surface of the prepreg with respect to 100% of the thickness of the prepreg. preferable. Further, the interlayer cambium is preferably present on both the front and back surfaces of the prepreg from the viewpoint of improving convenience during the production of the carbon fiber reinforced composite material.

90 to 100% by weight, preferably 95 to 100% by weight, of the particles or fibers of [C], [D], and [E] are localized in the cambium. Is preferable.

The thickness of the cambium with respect to the prepreg and the abundance of the particles or fibers of the [C], [D], and [E] contained in the cambium shall be evaluated by, for example, the following method. Can be done.

The thickness of the interlayer formation layer with respect to the prepreg is such that a plurality of laminated prepregs are sandwiched between two smooth polytetrafluoroethylene resin plates and brought into close contact with each other, and the temperature is gradually raised to the curing temperature over 7 days. Gelled and cured to prepare a plate-shaped prepreg cured product. This cured prepreg is used to magnify its cross section and take a picture. Using this cross-sectional photograph, the thickness of the cambium with respect to the prepreg is measured. Specifically, it is measured at at least 10 arbitrarily selected places of the cambium layer 2 between the carbon fiber layer 1 and the carbon fiber layer 1 on a photograph as shown in FIG. 1, and the average thereof is taken as the thickness of the cambium layer.

The abundance of the particles or fibers of [C], [D], and [E] contained in the cambium is such that a prepreg single layer is sandwiched between two surface smooth polytetrafluoroethylene resin plates. The fibers are brought into close contact with each other, and the temperature is gradually raised to the curing temperature over 7 days to gel and cure to prepare a plate-shaped prepreg cured product. On both sides of this cured prepreg, draw two lines parallel to the surface of the prepreg at a depth of 20% of the thickness from the surface of the cured prepreg. Next, the total area of the particles or fibers existing between the surface of the prepreg and the line and the total area of the particles or fibers existing over the thickness of the prepreg are obtained, and the total area of the particles or fibers existing over the thickness of the prepreg is calculated with respect to 100% of the thickness of the prepreg. Then, the abundance of particles or fibers present in the range of 20% depth from the surface of the prepreg is calculated. Here, the total area of the particles or fibers is obtained by hollowing out the particles or fiber portions from the cross-sectional photograph and converting from the weight thereof. If it is difficult to distinguish the particles dispersed in the resin after taking a photograph, a means for dyeing the particles can also be adopted.

Further, in the present invention, [C] thermoplastic resin particles or fibers, [D] conductive particles or fibers, and [E] thermoplastic resin cores or cores are coated with a conductive substance. Alternatively, the total amount of fibers is preferably in the range of 20% by weight or less with respect to the prepreg. If the total amount of the particles or fibers of [C], [D], and [E] exceeds 20% by weight with respect to the prepreg, it becomes difficult to mix with the base resin, and the tack and drape properties of the prepreg become difficult. May decrease. That is, in order to impart impact resistance while maintaining the characteristics of the base resin, the total amount of the particles or fibers of [C], [D], and [E] should be 20% by weight or less with respect to the prepreg. It is preferably, more preferably 15% by weight or less. In order to further improve the handling of the prepreg, it is more preferably 10% by weight or less. The total amount of the particles or fibers of [C], [D], and [E] is preferably 1% by weight or more, more preferably 2% by weight, based on the prepreg, in order to obtain high impact resistance and conductivity. % Or more.

In the present invention, [D] conductive particles or fibers and [B] thermosetting in the conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance, [B] thermosetting. Some of them have low adhesiveness to sex resins, but if they are surface-treated, strong adhesion to thermosetting resins can be realized, and impact resistance can be further improved. .. From this point of view, it is preferable to apply at least one treatment selected from the group consisting of coupling treatment, oxidation treatment, ozone treatment, plasma treatment, corona treatment, and blast treatment. Among them, those subjected to surface treatment by a coupling treatment, an oxidation treatment, or a plasma treatment capable of forming a chemical bond or a hydrogen bond with a thermosetting resin are more preferably used because they can realize strong adhesion to the thermosetting resin. ..

Further, in the above surface treatment, the surface treatment time is shortened, [D] conductive particles or fibers, and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance. Surface treatment can be performed using heating and ultrasonic waves to help disperse the 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, the environment may deteriorate, and the operating cost may increase.

As the coupling agent used in the coupling treatment, silane-based, titanium-based, and aluminum-based coupling agents are used, and these coupling agents may be used alone or in combination. If the coupling agent is not suitable, the impact resistance may decrease due to insufficient adhesion between the treated particles or fibers and the thermosetting resin. In order to avoid such a problem, it is preferable to use a coupling agent that has a strong affinity with the thermosetting resin to be used or that can chemically bond and realize strong adhesion. In order to enhance the affinity with the thermosetting resin, it is preferable to select a coupling agent having a substituent whose molecular structure and polarity are close to those of the thermosetting resin to be used.

In order to further reliably enhance the adhesiveness, it is preferable to use a coupling agent capable of forming a chemical bond with the thermosetting resin which is a matrix resin. When the resin to be radically polymerized, such as unsaturated polyester resin, diallyl phthalate resin, and maleimide resin, is a matrix resin, it is substituted with a vinyl group, an allyl group, an acryloyl group, a metachloroyl group, a cyclohexenyl group, etc. having a double bond. When the coupling agent having a group or the epoxy resin is a matrix resin, the coupling agent having an epoxy group, a phenolic hydroxyl group, a carboxyl group, a mercapto group, an amino group or a monosubstituted amino group, or the phenol resin is a matrix resin. In some cases, an epoxy group, a coupling agent having a phenolic hydroxyl group, and in the case where the urethane resin is a matrix resin, a coupling agent having a hydroxyl group, an amino group or a monosubstituted amino group, a melamine resin or a urea resin is a matrix. In the case of a resin, a coupling agent having an amide group, a ureido group, an amino group or a monosubstituted amino group, and in the case of a maleimide resin being a matrix resin, an amino group in addition to the coupling agent having a double bond. Alternatively, when the coupling agent having a monosubstituted amino group or the cyanate resin is a matrix resin, a coupling agent having a carboxyl group, an epoxy group, a hydroxyl group, an amino group or a monosubstituted amino group can be preferably used.

As the coupling treatment, the silane coupling treatment is preferable because it is easy to obtain a coupling agent having various functional groups. Specific examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, and 3- (phenylamino). Propyltrimethoxysilane, 3- (2-aminoethyl) aminopropylmethyldimethoxysilane, etc., and epoxysilanes are 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxy. Propylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. Vinyl silane is vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris ( Examples thereof include 2-methoxyethoxy) silane and vinyl triacetoxysilane. In particular, a silane coupling agent having an epoxy group, an amino group or a monosubstituted amino group in the molecule is particularly preferably used because it can be applied to a wide range of resins and has high reactivity.

In the present invention, [D] conductive particles or fibers and [E] conductive particles or fibers in which the core or core of the thermoplastic resin is coated with a conductive substance (hereinafter, also referred to as an object to be treated). In the case of coupling treatment, it is preferable to add a coupling agent in an amount of preferably 0.01 to 30 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of these particles or fibers. If the amount of the coupling agent is too small, the adhesiveness with the thermosetting resin may not be sufficiently exhibited, and conversely, if the amount is too large, the mechanical properties of the cured product may deteriorate.

In the present invention, the coupling agent may be attached to the object to be treated and heat-treated directly to perform the coupling treatment, or the coupling agent and the object to be treated may be added to the thermosetting resin in advance to cure the prepreg. Coupling treatment may be performed by the heat treatment at the time.

The oxidation treatment is not particularly limited as long as the surface of the object to be treated can be oxidized, but a chemical solution oxidation treatment and an electrolytic oxidation treatment can be used. Of these, the chemical oxidation treatment is preferably used.

The chemical solution oxidation treatment is a method of oxidizing treatment in an acidic aqueous solution. Examples of the acidic aqueous solution include sulfuric acid, fuming sulfuric acid, nitric acid, fuming nitric acid, hydrochloric acid, phosphoric acid, carbonic acid, boric acid, oxalic acid, hydrofluoric acid, formic acid, butyric acid, acetic acid, boring sulfuric acid, chlorosulfate, chloroacetic acid, sulfosalicylic acid. Sulfacetic acid, maleic acid, chromium anhydride, hypochlorous acid, acrylic acid, sulfonic acid, fluorosulfate, trifluoromethanesulfate, trifluoromethanesulfonic acid, ammonium sulfate, ammonium formate, ammonium dihydrogen phosphate, ammonium oxalate, hydrogen sulfate An aqueous solution containing ammonium or the like may be used alone or in combination. By the oxidation treatment, functional groups such as hydroxyl groups and carboxyl groups are chemically generated on the object to be treated, and the functional groups chemically bond with the matrix resin and / or hydrogen bond to realize strong adhesion. Of these, sulfuric acid, nitric acid, or a mixed acid thereof, which are strongly acidic, are preferably used.

The concentration of the acidic aqueous solution is preferably 0.01% by weight or more, more preferably 10% by weight or more, and further preferably 50% by weight or more. The higher the concentration, the shorter the treatment time and the effect of loosening the agglomeration of the object to be treated. It is preferable to add an oxidizing agent such as ozone, hydrogen peroxide, or lead dioxide to the acidic aqueous solution because the oxidizing power is further increased.

As the surface treatment with ozone, a method of introducing ozone into a chamber having a heater and heat-treating the object to be treated is generally preferably used. In this case, the surface of the particles or fibers is modified to an activated surface, the surface wettability with the matrix resin is greatly improved, and strong adhesion can be realized. Further, a method of irradiating the object to be treated with ultraviolet rays in an ozone atmosphere to perform photooxidation treatment is also preferably used.

As the surface treatment with plasma, a method of introducing a reactive gas into the chamber and performing the plasma treatment under reduced pressure is preferably used. Reactive gases include helium, neon, argon, nitrogen, ammonia, oxygen, nitrous oxide, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, bromine cyanide, hydrogen cyanide, hydrogen, steam, air, and sulfite gas. , Hydrogen sulfide, etc. may be used alone or in combination. By applying plasma treatment to the object to be treated, the activated surface is modified, the surface wettability with the matrix resin is greatly improved, and strong adhesion can be realized.

As the discharge frequency (alternating current) of plasma, high frequency, low frequency, microwave can be used, and direct current can also be used. As the processing device, there are an internal electrode method in which the electrodes are installed inside the vacuum device and an external electrode method in which the electrodes are installed outside the vacuum device. In the present invention, either method can be used. The shape of the electrode can be a flat plate, a rod, a cylinder, etc. in combination depending on the purpose, but the discharge electrode is made of a metal rod coated with glass, and the ground electrode is made of metal, for example, stainless steel. It is preferable to use a plate or drum-shaped material at a distance between electrodes of preferably 0.5 to 30 cm, more preferably 2 to 10 cm, because the discharge is not uneven and uniform treatment can be performed. The electrodes are preferably cooled with water or the like, if necessary.

Examples of the surface treatment by corona treatment include JP-A-48-5043, JP-A-47-51905, JP-A-47-28067, JP-A-49-83767, and JP-A-51-41770. The method disclosed in Japanese Patent Application Laid-Open No. 51-131576 can be used. By applying the corona treatment to the object to be treated, the activated surface is modified, the surface wettability with the matrix resin is greatly improved, and strong adhesion can be realized.

There are two types of surface treatment by blasting: wet method and dry method. Fine-grained projectile material mixed with water or compressed air flow is used for [D] conductive particles or fibers, and [E] thermoplastic resin. It is performed by spraying the core or core onto the surface of conductive particles or fibers coated with a conductive substance, and is a treatment method preferably used for conductive fibers of [D] and [E]. As a result, the surface area is expanded by forming fine irregularities on the surface thereof, and the adhesive force between the matrix resin and the object to be treated can be increased. Examples of the type of projection material include glass beads, silicic anhydride, alumina, diamond, red iron oxide and the like. The particle size of the projection material is often about 100 to 5000 μm. Generally, by setting the type and particle size of the projecting material and the injection pressure of the projecting material according to the purpose, it is possible to perform surface treatment to the optimum surface roughness.

The prepreg of the present invention can be produced by applying a known method as disclosed in JP-A No. 1-26651, JP-A-63-170427 or JP-A-63-170428. ..

Specifically, the following three methods can be exemplified.

The first method is to apply pressure to both sides or one side of [A] carbon fibers that are aligned in a sheet shape with a resin film coated with [B] thermosetting resin on a release paper or the like. B] A primary prepreg is prepared by impregnating with a thermosetting resin, and another resin film containing at least one of the following (1) and (2) in [B] thermosetting resin is applied to both sides or one side thereof. It is a method of pasting. (1) [C] Thermoplastic resin particles or fibers, and [D] Conductive particles or fibers (2) [E] Conductive particles or fibers in which the core or core of a thermoplastic resin is coated with a conductive substance.

Here, instead of attaching another resin film containing at least one of (1) and (2) in [B] thermosetting resin, at least one of (1) and (2) is attached. It is also possible to spray or attach only one on the primary prepreg.

The second method is to apply at least the above (1) and (2) to the surface of another resin film in which the primary prepreg produced by the first method is coated with [B] thermosetting resin on a paper pattern or the like. This is a method of spraying or pasting either one on both sides or one side of the primary prepreg.

In the third method, a resin film obtained by coating a [B] thermosetting resin containing at least one of the above (1) and (2) on a paper pattern or the like is arranged in a sheet shape [A]. ] This is a method for producing a prepreg by impregnating a [B] thermosetting resin containing at least one of (1) and (2) above by applying pressure to both sides or one side of carbon fibers.

The carbon fiber reinforced composite material of the present invention can be produced by laminating the above-mentioned prepreg of the present invention, pressurizing and heating to cure the [B] thermosetting resin. Here, as a method of applying pressure and heating, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method and the like are adopted, and the autoclave molding method is particularly preferably used.

The carbon fiber reinforced composite material of the present invention is widely used in aerospace applications, general industrial applications, etc. because it is excellent in strength, rigidity, impact resistance, conductivity, and the like. More specifically, in aerospace applications, aircraft primary structural members such as main wings, tails and floor beams, aircraft secondary structural members such as flaps, ailerons, cowls, fairings and interior materials, rocket motor cases and man-made It is preferably used for satellite structural materials. Among such aerospace applications, the carbon fiber reinforced composite material according to the present invention is particularly preferably used in aircraft primary structural material applications that require impact resistance and lightning resistance, particularly in fuselage skins, main wing skins, and tail wing skins. .. In general industrial applications, structural materials for moving objects such as automobiles, ships and railroad vehicles, drive shafts, leaf springs, windmill blades, pressure vessels, fly wheels, papermaking rollers, roofing materials, cables, reinforcing bars, ICs. It is preferably used for computer applications such as trays and laptop housings, and for civil engineering and building materials 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 outer panels, ship outer panels, railway outer panels, wind turbine blades, and housings for IC trays and notebook computers.

<p> Hereinafter, the present invention will be described in more detail with reference to Examples. The following raw materials were used to obtain the prepregs of each example.</p><p> &lt;Carbon fiber&gt; "Treca (registered trademark)" T800S-24K-10E (24,000 fibers, tensile strength 5.9 GPa, tensile elastic modulus 290 GPa, carbon fiber with tensile elongation 2.0%, manufactured by Toray Industries, Inc.) -"Treca (registered trademark)" T700S-24K-50C (24,000 fibers, tensile strength 4.9 GPa, tensile elastic modulus 230 GPa, carbon fiber with tensile elongation 2.1%, manufactured by Toray Industries, Inc.).</p><p> &lt;Thermosetting resin&gt; Bisphenol A type epoxy resin, "Epicoat (registered trademark)" 825 (manufactured by Japan Epoxy Resin Co., Ltd.) Tetraglycidyl diaminodiphenylmethane, ELM434 (manufactured by Sumitomo Chemical Co., Ltd.) -Polyester sulfone with a hydroxyl group at the end "Sumika Excel (registered trademark)" PES5003P (manufactured by Sumitomo Chemical Co., Ltd.) 4,4'-Diaminodiphenyl sulfone (manufactured by Mitsui Kagaku Fine Co., Ltd.).</p><p> &lt;Thermoplastic resin particles&gt; Nylon 12 particles SP-10 (manufactured by Toray Industries, Inc., shape: true sphere) -Epoxy-modified nylon particles A obtained by the following manufacturing method Transparent polyamide (trade name "Grillamide (registered trademark)"-TR55, manufactured by Msaberge) 90 parts by weight, epoxy resin (trade name "Epicoat (registered trademark)" 828, manufactured by Yuka Shell Co., Ltd.) 7.5 parts by weight and A uniform solution is obtained by adding 2.5 parts by weight of a curing agent (trade name "Tohmide (registered trademark)" # 296, manufactured by Fuji Kasei Kogyo Co., Ltd.) to a mixed solvent of 300 parts by weight of chloroform and 100 parts by weight of methanol. It was. Next, the obtained uniform solution was atomized using a spray gun for painting, stirred well and sprayed toward the liquid surface of 3000 parts by weight 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 spherical epoxy-modified nylon particles A.</p><p> Epoxy-modified nylon particles A are press-molded into a resin plate, and then G by the compact tension method based on ASTM D 5045-96._1cWhen the value was measured, 4420J / m²Met.</p><p> &lt;Thermoplastic resin fiber&gt; -TR-55 short fiber obtained by the following manufacturing method TR-55 short fiber (fiber length 1 mm) with a perfect circular cross section by cutting the fiber of transparent polyamide (trade name "Grillamide (registered trademark)" -TR55, manufactured by Mzaberke Co., Ltd.) discharged from a mouthpiece with one orifice. ) Was obtained.</p><p> After press molding TR-55 into a resin plate, G by the compact tension method based on ASTM D 5045-96._1cWhen the value was measured, 4540J / m²Met.</p><p> &lt;Conductive particles&gt; -Divinylbenzene polymer particles plated with nickel and then gold plated on them "Micropearl (registered trademark)" AU215 (manufactured by Sekisui Chemical Co., Ltd., shape: true sphere, specific gravity: 1.8 g / cm³, Thickness of conductive layer: 110 nm, [Volume of core] / [Volume of conductive layer]: 22.8).</p><p> -Divinylbenzene polymer particles are plated with nickel and then gold is plated. Particle "Micropearl (registered trademark)" AU225 (manufactured by Sekisui Chemical Co., Ltd., shape: true sphere, specific gravity: 2.4 g / cm³, Thickness of conductive layer: 200 nm, [Volume of core] / [Volume of conductive layer]: 20.2).</p><p> -Glass-like carbon particles "Belpearl (registered trademark)" C-2000 (manufactured by Air Water Inc., shape: true sphere, specific gravity: 1.5 g / cm³)。 </p><p> -Conductive particles B (shape: true sphere, specific gravity: 1.3 g / cm) obtained by the following manufacturing method³) 0.01 g of ferrous acetate (manufactured by Aldrich) and 0.21 g of cobalt acetate tetrahydrate (manufactured by Nacalai Tesque) were added to 40 mL of ethanol (manufactured by Nacalai Tesque) and suspended in an ultrasonic cleaner for 10 minutes. To this suspension, 2.0 g of crystalline titanosilicate powder (Titanosilicate® manufactured by MeOH Cat Co., Ltd.) (TS-1) was added, treated with an ultrasonic cleaner for 10 minutes, and treated at 60 ° C. By removing methanol at a constant temperature of TS-1, a solid catalyst in which the metal acetate was carried on the crystal surface of TS-1 was obtained.</p><p> 1.0 g of the solid catalyst prepared above was placed on a quartz boat in the center of a quartz tube having an inner diameter of 32 mm, and argon gas was supplied at 600 cc / min. A quartz tube was placed in an electric furnace and the center temperature was heated to a temperature of 800 ° C (heating time 30 minutes). When the temperature reaches 800 ° C, supply high-purity acetylene gas (manufactured by High Pressure Gas Industry Co., Ltd.) at 5 cc / min for 30 minutes, then stop supplying acetylene gas, cool the temperature to room temperature, and hollow carbon. The composition containing the nanofibers was taken out. 0.4 g of the obtained composition containing hollow carbon nanofibers was placed in an electric furnace and heated to 400 ° C. (heating time 40 minutes) in an atmospheric atmosphere. After holding at a temperature of 400 ° C. for 60 minutes, it was cooled to room temperature. Further, the composition containing the hollow carbon nanofibers was put into 200 mL of a sodium hydroxide aqueous solution having a concentration of 2.5 mol / L, and then stirred for 5 hours while maintaining the temperature at 80 ° C. Then, suction filtration was performed with a membrane filter having a pore size of 10 μm, and solid-liquid separation was performed. The obtained solid was washed with 1 L of distilled water, charged into 50 mL of sulfuric acid having a concentration of 5.1 mol / L, and stirred for 2 hours while maintaining the temperature at 80 ° C. Then, the solid matter was separated using filter paper (manufactured by Toyo Filter Paper Co., Ltd.), Filter Paper No. 2, 125 mm. The solid matter on the filter paper was washed with 500 mL of distilled water and then dried at a temperature of 60 ° C. to obtain hollow carbon nanofibers with a recovery rate of 90%.</p><p> In 100 ml of ethanol, 5 g of the hollow carbon fiber obtained above and 23 g of the epoxy-modified nylon particles A obtained in the above section of thermoplastic resin particles were placed and stirred for 1 hour to obtain a suspension. The obtained suspension was concentrated under reduced pressure. Subsequently, the material was heated at a temperature of 200 ° C. under an argon atmosphere and cured to obtain 25 g of conductive particles B. When the cross section of the conductive particles B was observed with a scanning electron microscope, the conductive layer was covered with a thickness of 300 nm. [Volume of core] / [Volume of conductive layer] was 7.0.</p><p> -Conductive particles C obtained by the following manufacturing method Epoxy modified nylon particles A are placed on a 10 g substrate on a sputtering device CFS-4ES-231 (manufactured by Shibaura Mechatronics Co., Ltd.), the target is copper, the gas component is argon, and the gas pressure is 2.0 × 10.^-1Conductive particles C having a conductive layer thickness of 110 nm were produced under the conditions of Pa, a substrate temperature of 80 ° C., and a power of 500 W. The shape of the conductive particles is a true sphere, and the specific gravity is 1.4 g / cm.³, [Volume of core] / [Volume of conductive layer] was 18.6.</p><p> -Conductive particles D obtained by the following manufacturing method Epoxy modified nylon particles A are placed on a 10 g substrate on a sputtering device CFS-4ES-231 (manufactured by Shibaura Mechatronics Co., Ltd.), the target is titanium, the gas component is argon, and the gas pressure is 3.0 × 10.^-1Conductive particles D having a conductive layer thickness of 130 nm were produced under the conditions of Pa, a substrate temperature of 80 ° C., and a power of 500 W. The shape of the conductive particles is a true sphere, and the specific gravity is 1.3 g / cm.³, [Volume of core] / [Volume of conductive layer] was 15.7.</p><p> -Conductive particles E obtained by the following manufacturing method 100 g of epoxy-modified nylon particles A was added to 1000 ml of electroless copper plating solution MK-430 (manufactured by Muromachi Chemical Co., Ltd.), and then plating was performed at 50 ° C. for 45 minutes to prepare conductive particles E. The shape of the conductive particle E is a true sphere, and the specific gravity is 1.4 g / cm.³The thickness of the conductive layer was 120 nm, and the [volume of core] / [volume of conductive layer] was 17.0.</p><p> -Conductive particles F obtained by the following manufacturing method 100 g of epoxy-modified nylon particles A was added to 1000 ml of electroless nickel plating solution NLT-PLA (manufactured by Nikko Metal Plating Co., Ltd.), and then plating was performed at 50 ° C for 60 minutes to prepare conductive particles F. .. The shape of the conductive particle F is a true sphere, and the specific gravity is 1.4 g / cm.³The thickness of the conductive layer was 180 nm, and the [volume of core] / [volume of conductive layer] was 11.2.</p><p> -Conductive particles G obtained by the following manufacturing method Transparent polyamide (trade name "Grillamide (registered trademark)"-TR55, manufactured by Msaberge) 60 parts by weight, epoxy resin (trade name "Epicoat (registered trademark)" 828, manufactured by Yuka Shell Co., Ltd.) 30 parts by weight and A uniform solution is obtained by adding 10 parts by weight of a curing agent (trade name "Tohmide (registered trademark)" # 296, manufactured by Fuji Kasei Kogyo Co., Ltd.) to a mixed solvent of 300 parts by weight of chloroform and 100 parts by weight of methanol. It was. Next, the obtained uniform solution was atomized using a spray gun for painting, stirred well and sprayed toward the liquid surface of 3000 parts by weight 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 spherical epoxy-modified nylon particles H.</p><p> 100 g of epoxy-modified nylon particles H were added to 1000 ml of electroless copper plating solution MK-430 (manufactured by Muromachi Chemical Co., Ltd.), and then plating treatment was performed at 50 ° C. for 45 minutes to prepare conductive particles G. The shape of the conductive particles G is a true sphere, and the specific gravity is 2.2 g / cm.³The thickness of the conductive layer was 320 nm, and the [volume of core] / [volume of conductive layer] was 6.2.</p><p> Epoxy-modified nylon particles H are press-molded into a resin plate, and then G by the compact tension method based on ASTM D 5045-96._1cWhen the value was measured, 1210J / m²Met.</p><p> -Surface-treated product I of "Micropearl (registered trademark)" AU215 obtained by the following manufacturing method 2 parts by weight of 3- (phenylamino) propyltrimethoxysilane was sprayed onto 100 parts by weight of "Micropearl (registered trademark)" AU215 with stirring with a mixer, and then heat-treated at 100 ° C for 12 hours to obtain "Micropearl (registered trademark)". A surface-treated product I of AU215 (registered trademark) was obtained.</p><p> -Surface-treated product J of "Belpearl (registered trademark)" C-2000 obtained by the following manufacturing method Add 100 g of "Belpearl®" C-2000 to 150 ml of 98 wt% sulfuric acid solution and 50 ml of 60 wt% nitric acid solution, then stir at 120 ° C for 20 minutes, separate with a filter and wash thoroughly with water. Then, a surface-treated product J of "Belpearl (registered trademark)" C-2000 was obtained.</p><p> &lt;Conductive fiber&gt; "Trading Card (Registered Trademark)" Milled Fiber MLD-30 (manufactured by Toray Industries, Inc., cross-sectional shape: perfect circle, specific gravity: 1.8 g / cm³, Fiber length 30 μm) "Trading Card (registered trademark)" chopped fiber T008-3 (manufactured by Toray Industries, Inc., cross-sectional shape: perfect circle, specific gravity: 1.8 g / cm³, Fiber length 3mm).</p><p> -Conductive fiber A obtained by the following manufacturing method 100 g of TR-55 short fiber (fiber length 1 mm) was added to 1000 ml of electroless copper plating solution MK-430 (manufactured by Muromachi Chemical Co., Ltd.), and then plating was performed at 50 ° C for 45 minutes, and conductive fiber A Was produced. The cross-sectional shape of conductive fiber A is a perfect circle, and the specific gravity is 1.6 g / cm.³The thickness of the conductive layer was 100 nm, and the [volume of the core] / [volume of the conductive layer] was 13.3.</p><p> Also, the average of [C] thermoplastic particles or fibers, [D] conductive particles or fibers, and [E] thermoplastic particles or fibers whose cores or cores are coated with a conductive material. The abundance of the [C], [D], and [E] particles or fibers present in the diameter, depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber reinforced composite. The measurement was performed under the following conditions. Unless otherwise specified, measurements were taken in an environment with a temperature of 23 ° C and a relative humidity of 50%.</p><p> (1) Represented by the mean diameter of the particles of [C], [D], and [E] and the [volume of the nucleus] / [volume of the conductive layer] of the conductive particles coated with the conductive substance. Volume ratio measurement Regarding the average particle size of the particles, for example, the particles are magnified 1000 times or more with a microscope such as a scanning electron microscope, photographed, randomly selected particles, and the diameter of the circumscribing circle of the particles is used as the particle size. , It was calculated as the average value of the particle size (n = 50). In addition, when calculating the volume ratio expressed by the [volume of the nucleus] / [volume of the conductive layer] of the conductive particles coated with the conductive substance, first, the average diameter of the nuclei of the conductive particles (average grain) is calculated. The diameter) was measured by the above method, and then the cross section of the conductive particles coated with the conductive substance was magnified 10,000 times with a scanning microscope and photographed, and the thickness of the conductive layer was measured (). n = 10) and calculated the average value. Such measurements were performed on the above randomly selected conductive particles (n = 50). The average particle size (average particle size) of the conductive particles was obtained by adding twice the average particle size of the nuclei of the conductive particles and the average value of the thickness of the conductive layer. Then, using the average diameter (average particle size) of the nuclei of the conductive particles and the average diameter (average particle size) of the conductive particles, the volume ratio expressed by [volume of the nucleus] / [volume of the conductive layer]. Was calculated. When the particles were non-spherical, the calculated value calculated assuming a circumscribed sphere of the nucleus and a sphere covered with a conductive layer measured by the above method was used for the volume ratio.</p><p> The average particle size measurement results of the thermoplastic resin particles and the conductive particles were as follows.</p><p> &lt;Thermoplastic resin particles&gt; Nylon 12 particles SP-10 (manufactured by Toray Industries, Inc.) 10.2 μm -Epoxy-modified nylon particles A: 12.5 μm.</p><p> &lt;Conductive particles&gt; "Micropearl" AU215 15.5μm "Micropearl" AU225 25.0 μm "Belpearl" C-2000 15.3 μm Conductive particles B 13.8 μm Conductive particles C 12.7 μm Conductive particles D 12.9 μm Conductive particles E 12.7 μm Conductive particles F 13.0 μm Conductive particles G 13.1 μm Surface-treated product of "Micro Pearl" AU215 I 15.5 μm Surface-treated product of "Belpearl" C-2000 J 15.3 μm.</p><p> (2) Represented by the average fiber diameter of the fibers of [C], [D], and [E] and the volume of the core of the conductive fiber coated with the conductive substance / the volume of the conductive layer. Volume ratio measurement Regarding the average fiber diameter (average fiber diameter), for example, the fiber cross section is magnified 1000 times or more with a microscope such as a scanning electron microscope, and a photograph is taken. The diameter of the circle was taken as the fiber diameter, and the average value of the fiber diameters (n = 50) was obtained. When determining the volume ratio represented by [volume of core] / [volume of conductive layer] of conductive fibers coated with a conductive substance, first, the average fiber diameter of the cores of conductive fibers is calculated as described above. It was measured by the method. After that, the cross section of the conductive fiber coated with the conductive substance is magnified 10,000 times with a scanning microscope, photographed, the thickness of the conductive layer is measured (n = 10), and the average value is taken. Calculated. Such measurements were performed on the above randomly selected conductive fibers (n = 50). The average fiber diameter of the conductive fiber core is obtained by adding twice the average fiber diameter of the core of the conductive fiber and the average value of the thickness of the conductive layer. Then, using the average fiber diameter of the core of the conductive fiber and the average fiber diameter of the conductive fiber, the volume ratio expressed by [volume of the core] / [volume of the conductive layer] was calculated. The average fiber diameter measurement results of the thermoplastic resin fibers and the conductive fibers were as follows.</p><p> &lt;Thermoplastic resin fiber&gt; TR-55 short fiber 5.4 μm.</p><p> &lt;Conductive fiber&gt; "Trading Card" Milled Fiber MLD-30 7.2μm "Trading card" chopped fiber T008-3 6.9 μm -Conductive fiber A: 5.6 μm.</p><p> (3) Abundance of particles or fibers of [C], [D], and [E] present in the depth range of 20% of the thickness of the prepreg. The prepreg is sandwiched between two smooth polytetrafluoroethylene resin plates on the surface and brought into close contact with each other, and the temperature is gradually raised to 150 ° C over 7 days to gel and cure to form a plate-like resin. A cured product was prepared. After curing, it was cut from the direction perpendicular to the contact surface, and the cross section was polished and then magnified 200 times or more with an optical microscope so that the upper and lower surfaces of the prepreg were within the field of view and photographed. By the same operation, the distance between the polytetrafluoroethylene resin plates was measured at 5 points in the horizontal direction of the cross-sectional photograph, and the average value (n = 10) was taken as the prepreg thickness.</p><p> On both sides of the photograph of this cured prepreg, draw two lines parallel to the surface of the prepreg at a depth of 20% of the thickness from the surface of the cured prepreg, and then draw two lines parallel to the surface of the prepreg and the above line. The total area of the particles or fibers existing between them and the total area of the particles or fibers existing over the thickness of the prepreg are calculated, and the depth is 20% from the surface of the prepreg with respect to the thickness of the prepreg of 100%. The abundance of particles or fibers present in the range of was calculated. Here, the total area of the particles or fibers was obtained by hollowing out the particles or fiber portions from the cross-sectional photograph and converting from the weight thereof. When it was difficult to distinguish the particles dispersed in the resin after taking a photograph, the particles were appropriately dyed and photographed.</p><p> (4) Measurement of volume specific resistance of conductive particles or fibers Using the MCP-PD51 type powder resistance measurement system manufactured by Dia Instruments Co., Ltd., the sample is set in a cylindrical cell having 4 probe electrodes, and the thickness and resistance value of the sample are applied to the sample at a pressure of 60 MPa. Was measured, and the volume intrinsic resistance was calculated from the value.</p><p> The volume-specific results of the conductive particles or fibers were as follows.</p><p> &lt;Conductive particles&gt; "Micro Pearl" AU215 1.4 × 10^-3Ωcm "Micro Pearl" AU225 1.6 × 10^-3Ωcm "Belpearl" C-2000 2.0 × 10^-2Ωcm Conductive particles B 5.0 × 10^-2Ωcm Conductive particles C 3.5 × 10^-2Ωcm Conductive particles D 5.2 × 10^-2Ωcm Conductive particles E 4.5 × 10^-4Ωcm Conductive particles F 4.0 × 10^-2Ωcm Conductive particles G 6.1 × 10^-4Ωcm "Micropearl" AU215 surface treatment product I 1.4 × 10^-3Ωcm "Belpearl" C-2000 Surface-treated product J 2.0 × 10^-2Ω cm.</p><p> &lt;Conductive fiber&gt; "Trading Card" Milled Fiber MLD-30 6.6 × 10^-2Ωcm "Trading card" chopped fiber T008-3 9.3 × 10^-2Ωcm Conductive fiber A 7.1 × 10^-3Ω cm.</p><p> (5) Post-impact compression strength measurement of fiber reinforced composite material One-way prepreg, [+ 45 ° / 0 ° / -45 ° / 90 °]_3sIn the configuration, 24-ply laminates are pseudo-isotropically laminated, and 25 laminates are molded in an autoclave 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. Made. A sample of 150 mm in length × 100 mm in width was cut out from each of these laminates, and a 6.7 J / mm drop weight impact was applied to the center of the sample according to SACMA SRM 2R-94, and the compression strength after impact was determined.</p><p> (6) Measurement of conductivity of fiber reinforced composite material One-way prepreg, respectively [+ 45 ° / 0 ° / -45 ° / 90 °]_3sIn the configuration, 24-ply laminates are pseudo-isotropically laminated, and 25 laminates are molded in an autoclave 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. Made. From each of these laminates, a sample having a length of 50 mm and a width of 50 mm was cut out, and a sample was prepared by applying the conductive paste "Dotite" (registered trademark) D-550 (manufactured by Fujikura Kasei Co., Ltd.) on both sides. These samples were measured for resistance in the stacking direction by the four-terminal method using an R6581 digital multimeter manufactured by Advantest Co., Ltd., and the volume specific resistance was determined.</p><p> (Example 1) In a kneading device, 50 parts by weight of "Epicoat®" 825 and 50 parts by weight of ELM434 were mixed with 10 parts by weight of PES5003P and dissolved, and then 19.98 parts by weight of epoxy-modified nylon particles A and 0.02 parts by weight of epoxy-modified nylon particles A and 0.02 parts by weight. "Micropearl (registered trademark)" AU215 was kneaded, and 40 parts by weight of 4,4'-diaminodiphenylsulfone, which is a curing agent, was kneaded to prepare a thermosetting resin composition.</p><p> The prepared thermosetting resin composition is applied onto a paper pattern using a knife coater to 52 g / m.²Two resin films of the above were prepared. Next, the two resin films prepared above are laminated on the carbon fibers (T800S-24K-10E) arranged in one direction in a sheet shape from both sides of the carbon fibers, and the resin is impregnated by heating and pressurizing the carbon fibers. The grain is 190g / m²Then, a unidirectional prepreg having a weight fraction of 35.4% of the matrix resin was prepared.</p><p> Using the prepared unidirectional prepreg, the abundance of particles present in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured. The results obtained are shown in Table 1.</p><p> (Examples 2 to 24, Comparative examples 1 to 7) A prepreg was prepared in the same manner as in Example 1 except that the types and blending amounts of carbon fibers, thermoplastic resin particles or conductive particles were changed as shown in Tables 1 to 4. Using the prepared unidirectional prepreg, the abundance of particles present in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured.</p><p> (Example 25) In a kneading device, 10 parts by weight of PES5003P is mixed and dissolved in 50 parts by weight of "Epicoat (registered trademark)" 825 and 50 parts by weight of ELM434, and then 4,4'-diaminodiphenyl sulfone, which is a curing agent, is further dissolved. Was kneaded by 40 parts by weight to prepare a thermosetting resin composition. This matrix resin was used as the primary resin.</p><p> In a kneading device, 10 parts by weight of PES5003P was mixed and dissolved in 50 parts by weight of "Epicoat (registered trademark)" 825 and 50 parts by weight of ELM434, and then 62.5 parts by weight of epoxy-modified nylon particles A and 1.3 parts by weight of epoxy-modified nylon particles A and 1.3 parts by weight. "Micropearl (registered trademark)" AU215 was kneaded, and 40 parts by weight of 4,4'-diaminodiphenylsulfone, which is a curing agent, was kneaded to prepare a thermosetting resin composition. This matrix resin was used as a secondary resin.</p><p> The prepared primary resin is applied on a paper pattern using a knife coater to 31.5 g / m.²Two resin films of the above were prepared. Next, the two resin films prepared above are laminated on the carbon fibers (T800S-24K-10E) arranged in one direction in a sheet shape from both sides of the carbon fibers, and the resin is impregnated by heating and pressurizing the carbon fibers. The grain is 190g / m²Then, a primary prepreg having a weight fraction of 24.9% of the matrix resin was prepared.</p><p> Next, the prepared secondary resin was applied on a paper pattern using a knife coater to 20.5 g / m.²Two resin films of the above were prepared. While the secondary resin films were faced to each other, the primary prepreg was passed through and impregnated with the resin by heating and pressurizing in the same manner as the primary prepreg to prepare a secondary prepreg. This prepreg has a carbon fiber basis weight of 190 g / m², A secondary prepreg having a matrix resin weight fraction of 35.4% was prepared. The matrix resin composition of this secondary prepreg is shown in Table 4.</p><p> Using the prepared secondary prepreg, the abundance of particles present in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured. The results obtained are shown in Table 4.</p><p> (Example 26) In a kneading device, 10 parts by weight of PES5003P is mixed and dissolved in 50 parts by weight of "Epicort (registered trademark)" 825 and 50 parts by weight of ELM434, and then 4,4'-diaminodiphenyl sulfone, which is a curing agent, is added. 40 parts by weight was kneaded to prepare a thermosetting resin composition.</p><p> The prepared thermosetting resin composition was applied onto a paper pattern using a knife coater to 45 g / m.²Two resin films of the above were prepared. Next, the two resin films prepared above were laminated on the carbon fibers (T800S-24K-10E) arranged in one direction in a sheet shape from both sides of the carbon fibers, and the resin was impregnated by heating and pressurizing. Furthermore, TR-55 short fibers, which are thermoplastic resin fibers, and "Trading card" milled fiber MLD-30, which is conductive fibers, were sprayed on both sides. The amount of spray is 6.5 g / m each²And 0.5g / m²Met. In this way, the carbon fiber basis weight is 190 g / m.²Then, a unidirectional prepreg having a weight fraction of 35.4% of the matrix resin was prepared.</p><p> Using the prepared unidirectional prepreg, the abundance of thermoplastic fibers and conductive fibers existing in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured. The results obtained are shown in Table 5.</p><p> (Examples 27 to 29) The type of thermoplastic resin fibers or particles, conductive particles or fibers was changed as shown in Table 5, and the amount of thermoplastic resin particles or fibers sprayed was 6.5 g / m.², And the amount of conductive particles or fibers sprayed is 0.5 g / m²A prepreg was prepared in the same manner as in Example 25, except that Using the prepared unidirectional prepreg, the abundance of the particles or fibers present in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured.</p><p> (Example 30, Comparative Examples 8 and 9) The types of thermoplastic resin fibers or conductive fibers were changed as shown in Table 5, and the amount of spraying them was 7.0 g / m.²A prepreg was prepared in the same manner as in Example 25, except that Using the prepared unidirectional prepreg, the abundance of the particles or fibers present in the depth range of 20% of the thickness of the prepreg, the post-impact compressive strength and conductivity of the fiber-reinforced composite material were measured.</p><p> The results obtained are summarized in Tables 1-5.</p><p><tables num="1"><img file="JP2010280903A_D0001.tif" /></tables></p><p><tables num="2"><img file="JP2010280903A_D0002.tif" /></tables></p><p><tables num="3"><img file="JP2010280903A_D0003.tif" /></tables></p><p><tables num="4"><img file="JP2010280903A_D0004.tif" /></tables></p><p><tables num="5"><img file="JP2010280903A_D0005.tif" /></tables></p><p> By comparison between Examples 1 to 6 and Comparative Examples 1 to 4, the carbon fiber reinforced composite material of the present invention specifically realizes high post-impact compression strength and low volume specific resistance, and has high impact resistance and conductivity. It can be seen that both sexes are compatible. In addition, the relationship between these results and the claims of the present invention is summarized in FIG. In FIG. 2, the weight ratio indicated by [blending amount of thermoplastic resin particles (parts by weight)] / [blending amount of conductive particles (parts by weight)] is taken on the horizontal axis, and "" is shown on the left vertical axis. The value of the compression strength after impact is shown, and is the value of the volume specific resistance shown on the right vertical axis. Generally, when the weight ratio indicated by [Amount of thermoplastic resin particles (parts by weight)] / [Amount of conductive particles (parts by weight)] is large, impact resistance is excellent but volume specific resistance is also large. Further, when the weight ratio indicated by [blending amount of thermoplastic resin particles (parts by weight)] / [blending amount of conductive particles (parts by weight)] is small, the volume specific resistance is small, but the impact resistance is inferior. It can be seen that the range of claim 1 in the present invention is a range in which low volume intrinsic resistance and high post-impact compression strength can be achieved, and both conductivity and impact resistance can be achieved at the same time.</p><p> The same can be said for these results by comparing Examples 7 to 30 with Comparative Examples 5 to 9. Furthermore, by comparing Example 3 and Example 7, Example 3 using T800S-24K-10E, which is a carbon fiber having a tensile modulus of 290 GPa, is more like T700S, which is a carbon fiber having a tensile modulus of 230 GPa. It can be seen that it is superior to Example 7 using -24K-50C. Further, as shown in Examples 14 to 30, various combinations of thermoplastic resin particles or fibers and conductive particles or fibers can be used in the present invention.</p><p> Compared with Examples 3 and 14, the surface-treated products of conductive particles as shown in Examples 20 and 21 can realize strong adhesion to the thermosetting resin and have higher post-impact compression strength. You can see that it has been achieved.</p><p> Further, in Examples 22 and 23, the thermoplastic resin particles are not used, and only the conductive particles E and G in which the core of the thermoplastic resin is coated with the conductive substance are used, or in Example 30, heat is used. Even if only the conductive fiber A in which the core of the thermoplastic resin is coated with the conductive substance is used without using the plastic resin fiber, low volume specific resistance and high post-impact compression strength can be achieved, and the conductivity is high. It can be seen that both impact resistance and impact resistance are achieved. Moreover, when comparing the conductive particles E and G of Examples 22 and 23, G_1cIt can be seen that the highly conductive particles E achieve higher post-impact compression strength. </p><p> It can be seen that in Example 25 using the secondary prepreg, the abundance of particles present at a depth of 20% is higher than in Example 3, and higher conductivity and impact resistance can be obtained.</p>

The prepreg and carbon fiber reinforced composite materials of the present invention have excellent impact resistance and conductivity, and are used for aircraft structural members, windmill blades, automobile outer panels, IC trays, laptop housings, etc. It can be widely deployed in computer applications and is useful.

1: Carbon fiber layer (inside the layer) 2: Cambium layer (interlayer) 3: Thermoplastic resin particles 4: Conductive particles 5: Carbon fiber 6: Thermosetting resin