JP5929046B2 - Carbon fiber fabric prepreg and carbon fiber reinforced composite material - Google Patents

Description

  The present invention relates to a fiber-reinforced composite material suitably used for aerospace applications, automobile applications, marine applications, sports and general industrial applications, and a prepreg for obtaining the same. More particularly, the present invention relates to a prepreg and a fiber reinforced composite material that are fiber reinforced composite materials exhibiting stable conductivity and that have excellent environmental fatigue characteristics, in particular using biaxial or higher woven fabric substrates.

  Fiber reinforced composite materials made of glass fiber, carbon fiber, aramid fiber, etc. and matrix resin are lightweight compared to competing metals, etc., but have excellent mechanical properties such as strength and elastic modulus. It is used in many fields such as spacecraft members, automobile members, ship members, civil engineering and building materials, and sports equipment. Particularly in applications where high performance is required, carbon fibers excellent in specific strength and specific elastic modulus are often used as reinforcing fibers. In addition, thermosetting resins such as unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins, cyanate ester resins, and bismaleimide resins are often used as matrix resins, with excellent adhesion to carbon fibers. Many epoxy resins are used. In applications where high performance is required, fiber reinforced composite materials using continuous fibers are used, and prepregs that combine reinforced fibers and uncured thermosetting resins are widely used as intermediate substrates for creating structures. It's being used.

  Transport aircraft applications such as aircraft and automobiles, and large structural material applications such as windmills are one of the applications in which the high specific strength and high specific modulus of the carbon fiber reinforced composite material are effectively exhibited. In these applications, measures against damage and deterioration due to severe natural environments such as temperature changes, wind and rain, and lightning strikes are considered important, and various methods have been considered.

  Carbon fiber reinforced composite materials use carbon fibers in combination with a matrix resin that generally has high insulation properties, so electrical conductivity is lower than that of metal materials. When a large current is generated by a lightning strike, the current is instantly diffused. Can not. Therefore, in a structural material using a carbon fiber reinforced composite material, there is a possibility that damage to the structural material may increase when a lightning strike occurs, compared to the case where a conventional metal material is used. In addition, when used in an aircraft or the like, there is a possibility that lightning will ignite the fuel or adversely affect internal electronic devices. In order to solve such a problem, a fiber reinforced composite material using a prepreg (for example, Patent Document 1) in which a reinforcing fiber and a metal mesh are combined, or a prepreg in which a carbon fiber woven metal wire is combined with a matrix resin. A method of creating a structure by using a method (for example, Patent Document 2) is known.

  On the other hand, in a temperature change, for example, a commercial aircraft is exposed to a temperature environment that is greatly different between flying in the sky and staying on the ground. In other words, it is at an extremely low temperature of about −50 ° C. in the sky, but reaches 70 ° C. or more depending on the area when staying on the ground. Each time it takes off and landing, the aircraft is repeatedly exposed to these extremely low and high temperatures. In such an environment, in a composite material in which carbon fiber is combined with a matrix resin, the linear expansion coefficient of carbon fiber is very small, so there is a large difference in linear expansion coefficient between carbon fiber and matrix resin, and expansion due to temperature changes.・ Strain, that is, thermal strain is applied to the matrix resin due to the shrinkage. Due to thermal strain, a fine crack (microcrack) of about several tens to several hundreds of μm may occur in the resin portion in the fiber reinforced composite material. When a load due to a temperature change from a high temperature to a low temperature (hereinafter sometimes referred to as a thermal cycle) is repeatedly exposed, the above-described microcracks are likely to occur (for example, Non-Patent Document 1). When environmental fatigue is further applied in a state where the microcracks are generated, the microcracks grow into larger cracks, and the mechanical properties of the fiber-reinforced composite material may be reduced by the cracks.

  In composite materials that combine metal wire, carbon fiber, and matrix resin to provide lightning strike resistance as described above, metal has a different coefficient of linear expansion from carbon fiber and matrix resin, so thermal strain due to thermal cycle loading is different. The influence is considered to be more complicated than the system that does not contain a metal wire, and the possibility of the occurrence of microcracks is considered to be even greater. In some cases, microcracks may be generated from the metal wire interface due to poor adhesion between the metal and the matrix resin, deterioration of adhesion due to corrosion of the metal wire, or the like.

  In the region where only the matrix resin concentrates in the fiber reinforced composite material (hereinafter sometimes referred to as the resin-rich part), the difference in linear expansion coefficient becomes significant, resulting in more microcracks due to environmental fatigue. (Patent Document 3, Non-Patent Document 1). When molding structural materials, carbon fiber bundles (yarns) are arranged in two or more directions from the viewpoint of ease of molding such as drape, reduction of surface anisotropy, and appearance. Carbon fiber woven prepregs may be used. In such a carbon fiber woven fabric substrate, the crimp (that the fibers are wavy) is overwhelmingly larger than when carbon fibers are arranged in one direction because of the intersection of warp and weft. As a result, A composite material obtained by laminating and forming a biaxial or more woven fabric base material as a prepreg has many resin-rich portions. That is, the carbon fiber reinforced composite material using the woven base material is more likely to generate microcracks due to the thermal cycle than the one using the unidirectional base material. Further, when metal wires having different fiber diameters are included, the resin-rich portion may be increased, and microcracks are more likely to occur. That is, it is an important issue to increase the environmental durability of the carbon fiber reinforced composite material using a base material including such a textile base material or a metal wire.

  A carbon fiber reinforced composite material containing a metal wire as described above is often combined with a fiber reinforced composite material containing no metal wire to produce a structure. For example, a carbon fiber reinforced composite material containing a metal wire only in a part of the structure, such as a surface layer of the structure, may be used. In order to increase the durability of the entire structure to the environment, it is important that no microcracks occur from any part.

  Thermosetting resins, especially resin cured products obtained by curing epoxy resin compositions, are generally more brittle than thermoplastic resins, so when they are used as a matrix resin in fiber reinforced composite materials, the inherent thermal strain Therefore, micro cracks are easily generated. In a fiber reinforced composite material using a thermosetting resin, in order to provide resistance to thermal strain, that is, to suppress the occurrence of microcracks due to thermal cycle loading, and to suppress the development of cracks generated, thermosetting It is an important issue to increase the elongation and toughness of the resin. In addition, when used for structural members, it is important to improve mechanical properties such as tensile strength and compressive strength of fiber-reinforced composite materials in order to withstand the load during use, and a material that combines microcrack resistance and high strength properties. Is required.

  As a method for increasing the toughness of a matrix resin, particularly a cured epoxy resin, a method of adding rubber to the epoxy resin composition is known. As a method for adding rubber, for example, a method using butadiene-acrylonitrile copolymer rubber (CTBN) or nitrile rubber having a reactive carboxyl group as a terminal group has been proposed (for example, Patent Documents 4 and 5). However, since this method goes through a process in which the rubber is once dissolved in the epoxy resin composition and then phase-separated at the time of curing, the morphology of the cured product changes depending on the type of epoxy resin composition and curing conditions, and the target The problem that the toughening effect cannot be obtained, and also because the rubber component is partially dissolved in the epoxy resin phase in the cured epoxy resin, the viscosity of the epoxy resin composition increases, the heat resistance of the cured epoxy resin (glass transition There are problems such as a decrease in temperature (Tg) and a decrease in elastic modulus, and the degree of freedom in design regarding setting of molding conditions and blending amount is low. In addition, depending on the blending amount and molding conditions, the mechanical properties such as tensile strength and compressive strength of the fiber reinforced composite material may be lowered, so that the resin has high toughness and the mechanical properties of the fiber reinforced composite material are maintained and improved. It has been demanded to achieve both.

  For this problem, in order to suppress the increase in viscosity of the epoxy resin composition and the decrease in Tg of the cured epoxy resin, core-shell polymer particles that are substantially insoluble in the epoxy resin are used, and the resin transfer molding (RTM) method is used. There has been proposed a method for achieving both mechanical properties such as compressive strength and microcrack resistance in a fiber-reinforced composite material obtained by molding (for example, Patent Documents 3 and 6). However, these techniques are RTM molding applications and are limited in the viscoelasticity of the resin. In addition, no solution has been presented in the case of containing conductive wires such as metals.

JP 2006-219078 A JP 2009-513438 A JP 2010-59300 A Japanese Patent Publication No. 61-29613 Japanese Patent Publication No.62-34251 JP 2009-280669 A

Journal of Advanced Materials (Journal of Advanced Materials), 26 (4), p48-62 (1995)

  The object of the present invention consists of a biaxial or more carbon fiber woven fabric and a metal wire mesh, nonwoven fabric, or metal wire, and a matrix resin, has high surface conductivity, and is excellent in fatigue resistance due to thermal cycling. Another object of the present invention is to provide a fiber-reinforced composite material that exhibits high tensile strength, and a prepreg suitable for obtaining the fiber-reinforced composite material.

The present invention has the following configuration in order to achieve the above object. That is, a prepreg that includes at least the following [A], [B], and [C], and [B] is arranged on one or both sides of [A].
[A] Biaxial or more carbon fiber woven fabric [B] [B1] Mesh or nonwoven fabric made of metal wire, and [B2] At least one selected from metal wire [C] At least [C1] thermosetting resin, [C2 ] A thermosetting resin composition comprising core-shell rubber particles, [C3] a thermoplastic resin soluble in the [C1] thermosetting resin, and [C1] the thermosetting resin is an epoxy having three or more functions. Resin and glycidyl aniline type epoxy resin or monofunctional epoxy resin, [C3] the thermoplastic resin is polyethersulfone, [C] in 100 parts by mass of the thermosetting resin composition, [C2] core shell 1-10 parts by weight rubber particles, [C3] thermoplastic resin is contained 8 parts 2, and, [C2] content of the core-shell rubber particles (parts by mass) [C3] of the thermoplastic resin containing The ratio between the ratio (parts by weight) is 0.321: 1 to 0.714: 1 range der Ru thermosetting resin composition or at least the following [A], [B2], including the [C] A prepreg having a configuration in which [B2] is arranged on the side surface of the carbon fiber bundle of [A].
[A] Biaxial or more carbon fiber fabric [B2] Metal wire [C] At least [C1] thermosetting resin, [C2] core shell rubber particles, [C3] Heat soluble in [C1] thermosetting resin [C1] The thermosetting resin includes a trifunctional or higher functional epoxy resin and a glycidyl aniline type epoxy resin or a monofunctional epoxy resin, and [C3]. The thermoplastic resin is polyethersulfone, and [C] 1 to 10 parts by mass of [C2] core shell rubber particles, and [C3] 2 to 8 parts by mass of the thermoplastic resin in 100 parts by mass of the thermosetting resin composition. And the ratio of the content ratio (parts by mass) of [C2] core-shell rubber particles to the content ratio (parts by mass) of [C3] thermoplastic resin is 0.321: 1 to 0.714: 1. range der of Ru thermosetting resin sets Things and a carbon fiber reinforced composite material obtained by curing the prepreg.

  The preferred embodiment of the [A] biaxial or higher carbon fiber fabric constituting the prepreg and carbon fiber reinforced composite material of the present invention is such that the carbon fiber used in [A] has a tensile modulus of 270 GPa or more in a strand tensile test. It is. [A] is preferably formed by arranging carbon fiber bundles (yarns) in two directions, the warp direction and the weft direction.

  Moreover, the preferable aspect of the prepreg of this invention and a carbon fiber reinforced composite material is a metal wire which comprises the mesh or nonwoven fabric which consists of said [B1] metal wire, or the diameter of said [B2] metal wire is 50-200 micrometers. It is. [B] in the prepreg of the present invention, that is, [B1] mesh or non-woven fabric made of metal wire, or [B2] metal wire is 5 parts per 100 parts by mass of [A] biaxial or more carbon fiber woven fabric. It is preferable that -40 mass parts is contained.

In a preferred embodiment of the [C] thermosetting resin composition constituting the prepreg and the carbon fiber reinforced composite material of the present invention, the elastic modulus of the cured resin obtained by curing [C] is 2.5 to 4.5 GPa. Preferably, K1c of the cured resin obtained by curing [C] is 0.65 to 1.5 MPa · m ^1/2 . [C1] The thermosetting resin component in [C] preferably contains an epoxy resin, and more preferably contains a trifunctional or higher functional epoxy resin.

  According to the present invention, a fiber-reinforced composite material that is excellent in fatigue resistance due to thermal cycling in addition to electrical conductivity in the plane direction and that exhibits high tensile strength, and a biaxial or higher carbon fiber woven prepreg suitable for obtaining the same. Can be obtained. In addition, the prepreg of the present invention is excellent in handleability. A fiber-reinforced composite material obtained by curing such a prepreg can be suitably used for a structure that requires electrical conductivity in the surface direction. In addition, since it has high resistance to thermal fatigue and exhibits high rigidity and high tensile strength, it can be suitably used as a structural material for aircraft, space applications, automobiles, ships, windmills, and the like.

It is a schematic diagram which shows the example of the state arrange | positioned on the single side | surface of [A]. It is a schematic diagram which shows another example of the state where [B] is arrange | positioned on the single side | surface of [A]. It is a schematic diagram which shows the example of the state by which [B] is arrange | positioned on both surfaces of [A]. It is a schematic diagram which shows the form arrange | positioned on the side surface of the carbon fiber bundle of [A] [B2].

  Hereinafter, the prepreg and fiber-reinforced composite material of the present invention will be described in detail.

  The component [A] in the prepreg of the present invention is a biaxial or more carbon fiber woven fabric, and is essential for developing the strength of the fiber-reinforced composite material obtained by curing the prepreg. A biaxial or more carbon fiber fabric is a fabric in which carbon fiber bundles (threads) are arranged in two or more directions. The arrangement of the carbon fiber bundles in two or more directions is to reduce the anisotropy of the cured fiber reinforced composite material, and to enhance the prepreg drapeability and facilitate the molding of the structural material. Is also a necessary requirement. By arranging the carbon fiber bundles in two or more directions, an isotropic laminate can be formed with a smaller number of laminates than in a unidirectional material.

  In order for the fiber reinforced composite material obtained by curing the prepreg of the present invention to exhibit higher rigidity and tensile strength, the carbon fiber constituting [A] is a strand tensile test according to the method described in JIS R 7601 (1986). The tensile elastic modulus is preferably 270 GPa or more. When the tensile elastic modulus is lower than 270 GPa, sufficient rigidity and tensile strength may not be exhibited when a fiber reinforced composite material is obtained. The tensile elastic modulus is more preferably 400 GPa or less. If the tensile elastic modulus exceeds 400 GPa, the tensile elongation of the carbon fiber tends to decrease, and there may be a case where sufficient tensile strength cannot be exhibited when a fiber-reinforced composite material is obtained. From the viewpoint of strength, since a composite material having high rigidity and mechanical strength can be obtained, carbon fibers having a strand tensile strength of 4.4 to 6.5 GPa in the strand tensile test are preferably used.

  From the viewpoint of draping properties, a biaxial woven fabric in which carbon fibers are arranged in two directions, a warp direction and a transverse direction, is preferable. More preferred is a woven structure selected from plain weave, twill weave and satin weave. In particular, plain weaving is easy to handle because it can be used without distinction between front and back. Twill weave and satin weave are preferable because the resin-rich portion where microcracks are likely to occur can be reduced by reducing the entanglement points of the fibers.

  The woven cover factor means the ratio of the area occupied by the woven yarn when it is made into a woven prepreg, but if this cover factor is small, the micro-crack when laminated and cured The resin-rich part that is prone to occur tends to be large. Moreover, when the cover factor is small, depending on the fluidity of the resin at the molding temperature, it becomes a void in which neither resin nor fiber exists, and the rigidity and strength of the resulting fiber reinforced composite material may be lowered. Further, when the cover factor is sufficient, it becomes easy to keep the resin on the surface of the prepreg, and it is possible to reduce the change with time of the prepreg tack. In order to solve the above, the range of the cover factor of [A] carbon fiber fabric is preferably 90 to 100%.

  [A] Carbon fiber bundles constituting a biaxial or more carbon fiber woven fabric are from the viewpoints of resin impregnation during prepreg production and molding, and surface smoothness and strength of a fiber-reinforced composite material obtained by curing the prepreg. The number of filaments in one fiber bundle is preferably in the range of 2500 to 30000. If the number of filaments is too small, the fibers tend to meander during the production of the prepreg, and as a result, the strength of the fiber-reinforced composite material using the prepreg may be reduced.

[A] The weight per unit area of the carbon fiber woven fabric of two or more axes (woven fabric basis weight) is appropriately selected according to the use, but the resin impregnation property at the time of prepreg production and curing molding, and the fabric at the time of production. From the viewpoints of handling property, handling property of the produced prepreg, and drapeability, those having a range of 100 to 320 g / m ² are preferably used. However, this does not apply depending on the application.

  Component [B] in the prepreg of the present invention, that is, [B1] mesh or non-woven fabric made of metal wire, or [B2] metal wire is the electric conduction in the surface direction of the fiber reinforced composite material obtained by laminating and curing the prepreg. It is an essential component for improving the properties. Here, the electrical conductivity in the surface direction refers to the electrical conductivity in the direction parallel to the surface of the carbon fiber fabric. When a current flows through a fiber reinforced composite material due to a lightning strike, the current preferentially flows through a mesh or metal wire made of a metal wire, and the current spreads over a wide area along the surface of the carbon fiber reinforced composite material, It is possible to prevent damage to the structure, ignition of the fuel, etc. by discharging electricity to another place of the member or discharging it to the atmosphere.

  From the viewpoint of efficiently diffusing current, the material of the metal wire of the component [B], that is, [B1] or [B2], preferably has an electrical resistivity smaller than that of carbon fiber, more preferably 2 minutes. 1 or less material. The electrical resistivity can be measured as follows, for example. 5 to 20 metal wires (metal wires constituting the mesh or non-woven fabric) or carbon fiber single yarn or fiber bundle are taken out as test pieces. The electrical resistance value specific to the volume is measured using a commercially available resistance meter, and the electrical resistivity is calculated using the length and cross-sectional area of the test piece. The average value of the test specimens used is determined and taken as the electrical resistivity. The electrical resistivity of the carbon fiber may be measured using a single yarn or may be evaluated in the form of a fiber bundle. When evaluated in the form of a fiber bundle, the specific electrical resistivity can be obtained using the length of the test piece, the cross-sectional area of the single yarn, and the number of single yarns contained in the fiber bundle. In order to evaluate a more accurate electric resistance value, it is preferable to measure by a four-terminal method, but if a difference between materials can be compared, it can also be measured by a simpler two-terminal method. The length of the short fiber to be taken out is required to be a length that provides a resistance value that can be measured in the measurement range of the resistance meter to be used. For non-woven fabrics and meshes, evaluation can be made with a shorter length. Conversely, an ohmmeter having an appropriate measurement range may be used according to the length of the test piece. As a commercially available high-performance electric resistance meter by the four-terminal method, there is a Loresta GP MCP-T610 type resistivity meter manufactured by Mitsubishi Chemical Analytech.

The electrical resistivity of a carbon material containing carbon fibers varies depending on structural defects and impurities contained in comparison with metals. The electrical resistivity in the major axis direction of carbon fiber and the surface direction of graphite is generally in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ Ω · m, and the material of [B] has a resistance value from this range. Is preferably small.

  Specific examples of the material of the metal wire [B] having the above characteristics, that is, [B1] or [B2] include gold, silver, copper, bronze, brass, aluminum, nickel, steel, and stainless steel. It is done. Other metallic materials with similar electrical and thermal characteristics can also be used. A plurality of materials selected from these materials can also be used in combination. In addition to electrical and thermal properties, considering the properties such as price, density, specific strength and rigidity, corrosion resistance, thermal expansion coefficient, etc., it is possible to select an appropriate material according to the application of the fiber reinforced composite material . Aluminum or other similar material has a relatively low density and excellent electrical and thermal properties. Stainless steel or the like can be used to improve corrosion resistance. Copper and copper alloys are preferably used because they are excellent in electrical conductivity and corrosion resistance and have a good balance with price.

  The diameter of the metal wire constituting the mesh or nonwoven fabric made of the [B1] metal wire or the [B2] metal wire is preferably 50 to 200 μm. If the diameter exceeds 200 μm, the weight fraction and volume fraction of [B] in the prepreg will increase, and not only will the effect of reducing the weight sufficiently be obtained when a fiber-reinforced composite material is used instead of metal. If the portion that is not reinforced with carbon fiber increases, there is a possibility that sufficient strength and rigidity will not be exhibited. In addition, when the diameter exceeds 200 μm, the resin-rich portion may increase and microcracks may be more likely to occur. The use of a conductive wire of 50 μm or more is preferable because the conductive wire can be prevented from being cut during the production of the prepreg, and the handleability is improved. Further, since the cross-sectional area is increased, a large current is easily diffused instantaneously. [B1] The conductive wire constituting the conductive mesh or nonwoven fabric, or the diameter of the [B2] conductive wire is more preferably in the range of 70 to 150 μm, but the application and combination [A] It can be set as appropriate according to the fineness of the carbon fiber bundle of the carbon fiber fabric (weight of the carbon fiber bundle per unit length), the fabric weight, and the like.

  [B] in the prepreg of the present invention, that is, [B1] mesh or non-woven fabric made of metal wire, or [B2] metal wire is 5 to 40 per 100 parts by mass of [A] biaxial or more carbon fiber woven fabric. It is preferable that a part by mass is included. When [B] is 5 parts by mass or more, a sufficient current spreading effect can be obtained. When the amount is more than 40 parts by mass, the weight fraction and volume fraction of [B] in the prepreg increase, and there may be cases where the effect of weight reduction sufficient for using a fiber-reinforced composite material instead of metal may not be obtained. Moreover, there is a possibility that sufficient strength / rigidity may not be exhibited due to an increase in the portion not reinforced with carbon fiber.

  In the present invention, [A] [B], that is, [B1] a mesh or non-woven fabric made of a metal wire, or [B2] a metal wire is arranged on one side or both sides or side surfaces of a biaxial or more carbon fiber woven fabric. create. As the structure in which [B] is arranged on one side of [A], [A] a structure in which [B] is arranged on one side of a carbon fiber fabric layer having two or more axes (FIG. 1), [A] carbon fiber A structure in which [B] is sandwiched between fabric layers (FIG. 2) can be mentioned. An example of the structure in which [B] is arranged on both sides of [A] is a structure in which a layer of [A] carbon fiber fabric is sandwiched between [B] (FIG. 3). Further, as shown in FIG. 4, even if the [B2] metal wire has a structure in which it is disposed directly beside the carbon fiber bundle that substantially constitutes [A], it is preferably used in the present invention. As a substrate composed of [A] and [B2] having such a structure, for example, those described in JP-A-2006-265769 can be used. 1 to 4 are schematic views illustrating three or two types of configurations that can be taken by a cross section perpendicular to the surface direction for each of the above-described arrangements.

  In addition, the form shown to Fig.1 (a)-(d) is typical, and even if the metal wire which comprises [B] is in full contact with the [A] carbon fiber fabric in an actual structure. , It may be partially touching or not touching. Moreover, although the cross section of the metal wire which comprises [B] was described in perfect circle shape, as long as the effect of this invention is not prevented, it may have cross-sectional shapes other than a perfect circle. Further, in the prepreg state, the space formed between the carbon fibers constituting [A] and [B] does not necessarily have to be filled with the matrix resin. In order to exhibit strength and environmental fatigue characteristics, it is necessary that the space formed between the carbon fibers constituting [A] and [B] is sufficiently filled with the matrix resin.

  The component [C] thermosetting resin composition in the prepreg of the present invention is a component that becomes a matrix resin of a fiber reinforced composite material, and improves handling and workability when a structure is formed using the prepreg. It is an essential ingredient to make it. [C] in the prepreg of the present invention contains at least [C1] thermosetting resin, [C2] core shell rubber particles, and [C3] a thermosetting resin that is soluble in the [C1] thermosetting resin. It is a resin composition.

  The solubility of [C3] in [C1] thermosetting resin is important for improving the mechanical properties, microcrack resistance, and solvent resistance of the resulting carbon fiber reinforced composite material. The term “soluble in [C1] thermosetting resin” described here means that a mixture of [C3] thermoplastic resin and [C1] thermosetting resin is heated or heated and stirred to obtain a uniform phase. It means that there exists a temperature region that makes Here, “to form a homogeneous phase” means that at least a state with no visual separation is obtained. As long as a uniform phase is formed in a certain temperature range, the separation may occur outside the temperature range, for example, at room temperature. Moreover, it can be evaluated also by the following method that [C3] is soluble in [C1]. That is, the change in viscosity was evaluated when [C3] powder was mixed with [C1] or the main component of [C1] and kept isothermal at a temperature lower than the melting point of [C3] for several hours, for example, 2 hours. When a substantial change in viscosity is sometimes observed, it may be determined that [C3] is soluble in [C1]. Thus, if [C3] has a property soluble in [C1], [C3] may cause phase separation in the process of curing the resin, but a cured resin obtained by curing. From the viewpoint of improving the solvent resistance of the carbon fiber composite material, it is more preferable not to perform phase separation during the curing process. Further, from the viewpoint of improving the mechanical properties, solvent resistance, and the like of the obtained carbon fiber reinforced composite material, it is more preferable to dissolve [C3] in [C1] in advance. It becomes easy to disperse | distribute uniformly in a thermosetting resin composition by making it melt | dissolve and mix.

  The [C1] thermosetting resin contained in [C] in the prepreg of the present invention is a resin that is cured by heat or external energy such as light or electron beam to at least partially form a three-dimensional cured product. If there is no particular limitation. Preferred thermosetting resins include epoxy resins, phenol resins, vinyl ester resins, unsaturated polyester resins, cyanate resins, maleimide resins, polyimide resins and the like. Among these, an epoxy resin is preferably used from the viewpoints of low curing shrinkage, heat resistance of the resin cured product, chemical resistance, mechanical properties, adhesion to carbon fibers, and the like.

  In the present invention, an epoxy resin is a compound having one or more epoxy groups in a molecule. An epoxy resin having N epoxy groups in a molecule is called an N-functional epoxy resin. The epoxy resin in the present invention may be one or more functional groups, but from the viewpoint of improving heat resistance and elastic modulus, the epoxy resin contained in [C1] preferably includes a trifunctional or more functional epoxy resin.

  In the trifunctional or higher functional epoxy resin, the number of functional groups is preferably 3 to 7, and more preferably 3 to 5. If the number of functional groups of the epoxy resin contained in [C1] is within such a preferable range, it is preferable from the viewpoint of the toughness of the cured resin after curing the thermosetting resin composition of the present invention.

  The trifunctional or higher functional epoxy resin is preferably selected from glycidylamine type epoxy resins and glycidyl ether type epoxy resins. Examples of the tri- or higher functional glycidylamine type epoxy resins include diaminodiphenylmethane type, diaminodiphenylsulfone type, aminophenol type, metaxylenediamine type, 1,3-bisaminomethylcyclohexane type, and isocyanurate type epoxy resins. Can be mentioned. Among them, diaminodiphenylmethane type and aminophenol type epoxy resins are particularly preferably used because of good balance between handleability and mechanical properties such as heat resistance and elastic modulus.

  Examples of the tri- or higher functional glycidyl ether type epoxy resin include epoxy resins such as phenol novolac type, orthocresol novolak type, phenol aralkyl type, trishydroxyphenylmethane type, and tetraphenylolethane type, and a binaphthalene skeleton. And epoxy resin.

  Other epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, urethane modified epoxy resin, hydantoin type epoxy resin, resorcinol type epoxy resin. , Epoxy resins having a bisarylfluorene skeleton, and glycidylaniline type epoxy resins.

  By blending the glycidyl aniline type epoxy resin, it is possible to control the viscoelasticity and fluidity of the resin, and to improve the mechanical properties such as the elastic modulus of the cured resin and the tensile strength of the fiber reinforced composite material. Examples of the glycidyl aniline type epoxy resin include diglycidyl aniline, monoglycidyl aniline, and derivatives having a substituent at one or more carbons selected from the 2, 3, 4, 5, and 6 positions of the benzene ring. . Examples of the substituent include aryl groups such as alkyl groups, phenyl groups, and naphthyl groups, alkyl ether groups such as methoxy groups, and aryl ether groups such as phenoxy groups.

By using a monofunctional epoxy resin in combination with the above trifunctional or higher functional epoxy resin and bifunctional epoxy resin, the viscoelasticity and fluidity of the resin, and the balance of mechanical properties such as the elastic modulus and toughness of the cured resin can be achieved. An excellent resin composition is obtained. Examples of the monofunctional epoxy resin include glycidyl phthalimide, glycidyl carbazole, phenyl glycidyl ether, phenyl phenyl glycidyl ether, and naphthyl glycidyl ether.

  By blending an epoxy resin having a skeleton with an aromatic ring substituted at the meta position or ortho position, an effect of improving mechanical properties such as the elastic modulus of the cured resin and the tensile strength of the fiber reinforced composite material can be obtained. Examples of the epoxy resin having an aromatic ring substituted at the meta position or ortho position in the skeleton include m (meth) -aminophenol type epoxy resin and 2,2 ′ type and 2,4 ′ type bonds. Examples thereof include bisphenol F type epoxy resin.

  By blending at least one kind of trifunctional or higher functional epoxy resin and at least one kind of bifunctional epoxy resin, it is possible to combine the fluidity of the resin and the heat resistance after curing. Moreover, the resin composition excellent also in mechanical characteristics, such as the elasticity modulus of a resin cured material, and the tensile strength at the time of using for a fiber reinforced composite material, can be obtained.

  Further, by combining a glycidylamine type epoxy resin and a glycidyl ether type epoxy resin, it becomes possible to achieve both heat resistance, water resistance and processability. Moreover, the tack property and drape property of a prepreg can be made appropriate by mix | blending at least 1 sort (s) of an epoxy resin which is liquid at normal temperature, and at least 1 sort (s) of solid epoxy resin at normal temperature.

  [C1] preferably contains at least one glycidylamine-type epoxy resin from the balance between adhesion to the reinforcing fibers and mechanical properties.

  Since liquid bisphenol A type epoxy resin, bisphenol F type epoxy resin and resorcinol type epoxy resin have low viscosity, they are combined with other epoxy resins in order to make processability and prepreg handling easy in prepreg production. It is preferable to use it.

  Solid bisphenol A-type epoxy resins and solid bisphenol F-type epoxy resins have a lower cross-linking density than liquid bisphenol A-type and bisphenol F-type epoxy resins, and thus have lower heat resistance but are more tough. Therefore, it is preferably used in combination with a glycidylamine type epoxy resin, a liquid bisphenol A type epoxy resin or a liquid bisphenol F type epoxy resin.

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

  Below, the example of the commercial item of the epoxy resin which can be included in [C1] thermosetting resin is given.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  An epoxy resin, an epoxy resin copolymerized with a thermosetting resin, or a modified epoxy resin may be used alone or in combination of two or more. Various characteristics can be added as described above by using a plurality of epoxy resins in combination.

  In the thermosetting resin composition of component [C] in the prepreg of the present invention, [C2] core-shell rubber particles are an essential component for improving the microcrack resistance of the carbon fiber reinforced composite material. Adding [C2] core-shell rubber particles to the thermosetting resin composition of component [C] also improves the mechanical properties (tensile strength) of the carbon fiber reinforced composite material passing through biaxial or more woven prepregs. It is effective. Here, the core-shell rubber particles are particles in which a part of or the whole of the core surface is coated by a method such as graft polymerization of a particulate core part mainly composed of a polymer such as a crosslinked rubber and a polymer different from the core part. Means.

  As the core portion of the core-shell rubber particles, a polymer polymerized from one or more selected from a conjugated diene monomer, an acrylate monomer, and a methacrylate ester monomer, or a silicone resin can be used. Specifically, for example, butadiene, isoprene, and chloroprene can be mentioned, and a crosslinked polymer constituted by using these alone or in plural kinds is preferable. Particularly, since the properties of the obtained polymer are good and the polymerization is easy, it is preferable to use butadiene as the conjugated diene monomer, that is, a polymer polymerized from a monomer containing butadiene as the core component. . In order to effectively develop the environmental fatigue characteristics of the carbon fiber reinforced composite material in the present invention, that is, the microcrack resistance, [C] the glass transition temperature Tg of the core portion of the core-shell rubber particles blended in the thermosetting resin composition is More preferably, it is −50 ° C. or lower.

  The shell component that constitutes the core-shell rubber particles is preferably graft-polymerized to the above-described core component and is chemically bonded to the polymer particles that constitute the core component. The component constituting the shell component is, for example, a polymer polymerized from one or more selected from (meth) acrylic acid esters, aromatic vinyl compounds and the like. In addition, in order to stabilize the dispersion state of the shell component, the component contained in the [C] thermosetting resin composition of the present invention, that is, [C1] a functional group that reacts with the thermosetting resin or its curing agent component. It is preferred that a group is introduced. When such a functional group is introduced, the affinity with the thermosetting resin is improved, and finally it can react with the thermosetting resin composition and be incorporated into the cured product. Good dispersibility can be achieved. As a result, a sufficient toughness improving effect can be obtained even with a small amount of blending, and toughness can be improved while maintaining the Tg elastic modulus. Examples of such functional groups include a hydroxyl group, a carboxyl group, and an epoxy group. As a method for introducing such a functional group into the shell portion, one or more components such as acrylic acid esters and methacrylic acid esters containing such a functional group are used as part of the monomer on the core surface. Examples thereof include a graft polymerization method.

  The [C2] core-shell rubber particles contained in the component [C] preferably have a volume average particle diameter in the range of 1000 nm. In particular, it is preferably 50 to 300 nm, and more preferably 50 to 150 nm. The volume average particle diameter can be measured using a nanotrack particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., dynamic light scattering method). Alternatively, a thin section of a cured product prepared with a microtome can be observed with a TEM, and the volume average particle diameter can be measured from the obtained TEM image using image processing software. In this case, it is necessary to use an average value of at least 100 particles. When the volume average particle diameter is 50 nm or more, the specific surface area of the core-shell rubber particles is moderately small and advantageous in terms of energy, so that aggregation does not easily occur and the effect of improving toughness is high. On the other hand, when the volume average particle diameter is 300 nm or less, the distance between the core-shell rubber particles is appropriately reduced, and the effect of improving toughness is high.

  There is no restriction | limiting in particular about the manufacturing method of [C2] core-shell rubber particle contained in component [C], The thing manufactured by the well-known method can be used. Commercially available core-shell rubber particles include, for example, “Paraloid (registered trademark)” EXL-2655 (Rohm & Haas) made of butadiene / alkyl methacrylate / styrene copolymer, acrylic ester / methacrylate copolymer. "STAPHYLOID (registered trademark)" AC-3355, TR-2122 (manufactured by Gantz Kasei Co., Ltd.), "PARALOID (registered trademark)" EXL-2611 made of butyl acrylate / methyl methacrylate copolymer EXL-3387 (manufactured by Rohm & Haas) or the like can be used. Further, a glassy polymer core layer having a glass transition temperature of room temperature or higher, such as Staphyloid IM-601, IM-602 (manufactured by Gantz Kasei Co., Ltd.) is covered with a rubbery polymer intermediate layer having a low Tg, Furthermore, a core-shell rubber particle having a three-layer structure, which is covered with a shell layer, can also be used. Usually, these core-shell rubber particles are handled in the form of a powder obtained by pulverizing them, and the powdered core-shell rubber is often dispersed again in the thermosetting resin composition. However, this method has a problem that it is difficult to stably disperse particles in a state without aggregation, that is, in a state of primary particles. To deal with this problem, do not remove the core-shell rubber particles once from the manufacturing process, but finally handle them in the form of a masterbatch dispersed in one component of a thermosetting resin, for example, an epoxy resin. A preferable dispersion state can be obtained by using a material that can be used. The core-shell rubber particles that can be handled in such a masterbatch state can be produced, for example, by the method described in JP-A No. 2004-315572. In this production method, first, a suspension in which core-shell rubber particles are dispersed is obtained by a method of polymerizing core-shell rubber in an aqueous medium represented by emulsion polymerization, dispersion polymerization, and suspension polymerization. Next, an organic solvent having partial solubility with water, such as a ketone solvent such as acetone or methyl ethyl ketone, or an ether solvent such as tetrahydrofuran or dioxane, is mixed into the suspension, and then a water-soluble electrolyte such as sodium chloride or chloride. Potassium is contacted, the organic solvent layer and the aqueous layer are phase-separated, and the aqueous layer is separated and removed to obtain an organic solvent in which core-shell rubber particles obtained are dispersed. Thereafter, after mixing the epoxy resin, the organic solvent is removed by evaporation to obtain a master batch in which the core-shell rubber particles are dispersed in the state of primary particles in the epoxy resin. As the core-shell rubber particle-dispersed epoxy masterbatch produced by such a method, “Kane Ace (registered trademark)” commercially available from Kaneka Corporation can be used.

  The content ratio (parts by mass) of [C2] core-shell rubber particles in component [C] is preferably 1 to 12 parts by mass in 100 parts by mass of [C] total thermosetting resin composition. More preferably, it is 10 mass parts. When the content is 1 part by mass or more, a cured product with higher fracture toughness is obtained, and when the content is 12 parts by mass or less, a cured product with higher elastic modulus is obtained. [C] In view of dispersibility of [C2] core-shell rubber particles in the thermosetting resin composition, the content is preferably 10 parts by mass or less.

  As a method of mixing [C2] core-shell rubber particles in [C], a commonly used dispersion method can be used. For example, a method using a three-roll, ball mill, bead mill, jet mill, homogenizer, rotation / revolution mixer and the like can be mentioned. Moreover, the method of mixing the above core-shell rubber particle-dispersed epoxy masterbatch can also be preferably used. However, even when dispersed in the form of primary particles, reaggregation may occur due to excessive heating or a decrease in viscosity. Therefore, when the core-shell rubber particles are dispersed and blended and mixed and kneaded with other components after the dispersion, it is preferably performed within a temperature and viscosity range in which re-aggregation of the core-shell rubber particles does not occur. Specifically, although it varies depending on the composition, for example, when kneading is performed at a temperature of 150 ° C. or higher, the viscosity of the composition may decrease and aggregation may occur. Therefore, it is preferable to knead at a lower temperature. However, in the case where the temperature reaches 150 ° C. or higher during the curing process, re-aggregation is hindered due to gelation at the time of temperature rise, and thus it can exceed 150 ° C.

  The [C] thermosetting resin composition in the prepreg of the present invention increases the resistance against carbon fiber reinforced composite material microcracks and improves mechanical properties, particularly tensile strength. It is essential to include a thermoplastic resin that is soluble in the resin. As described above, it is important that [C3] is soluble in [C1] thermosetting resin in order to improve the mechanical properties, microcrack resistance, and solvent resistance of the obtained carbon fiber reinforced composite material. is there. By blending a soluble thermoplastic resin with the thermosetting resin, the viscoelasticity of the matrix resin in the prepreg is controlled, and there is an effect of improving the handleability of the prepreg.

  Such thermoplastic resins are generally selected from the group consisting of carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, thioether bonds, sulfone bonds and carbonyl bonds in the main chain. A thermoplastic resin having a selected bond is preferable, but it may have a partially crosslinked structure. Moreover, these thermoplastic resins may have crystallinity or may be amorphous. More specifically, polyamide, polycarbonate, polyacetal, polyvinyl formal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, Examples include polyaramid, polyether nitrile, and polybenzimidazole. These thermoplastic resins may be used individually by 1 type, or may be used in combination of 2 or more types as appropriate.

  From the viewpoints of heat resistance and toughness of the cured resin and viscosity control of the uncured resin, polyethersulfone and polyetherimide are preferably used. As commercially available products of polyethersulfone, “Sumika Excel (registered trademark)” PES3600P, PES5003P, PES5200P, PES7600P (above, manufactured by Sumitomo Chemical Co., Ltd.), “Ultrason (registered trademark)” E2020P, E6020P (above, manufactured by BASFplastics) Etc. Examples of commercially available polyetherimides include “Ultem (registered trademark)” 1000, “Ultem (registered trademark)” 1010, “Ultem (registered trademark)” 1040 (above, manufactured by SABIC Innovative Plastics Co., Ltd.), and the like. It is done.

  As a method of blending these [C3] thermoplastic resin components into the [C] thermosetting resin composition, for example, it is mixed as a fine powder so as to dissolve in [C1] when the thermosetting resin composition is cured. However, from the viewpoint of further improving the solvent resistance when the resin cured product or the fiber reinforced composite material is used, it is preferable to dissolve and mix in the [C1] thermosetting resin component as described above. . By dissolving and mixing, the thermoplastic resin is easily distributed uniformly in the thermosetting resin composition, and the solvent resistance in the cured resin obtained by curing is improved, and the resulting carbon fiber reinforced composite It produces an effect on the tensile strength characteristics of the material. As a method of dissolving [C3] in [C1], in addition to a method of heating and stirring the mixture, the thermoplastic resin is a solvent having affinity with both a thermoplastic resin such as acetone, methyl ethyl ketone, and toluene and a thermosetting resin. That is, a method in which the solvent is dissolved in a common solvent, mixed with the thermosetting resin [C1] and made uniform, and then the solvent is distilled off by using a method such as heating and decompression, and the like.

  These thermoplastic resins have a functional group capable of reacting with the [C1] thermosetting resin or its curing agent component in the terminal or molecular chain from the viewpoint of affinity with the thermosetting resin used in the present invention. It is preferable. [C1] Having a functional group capable of reacting with the thermosetting resin or its curing agent component makes it easier to prevent separation and precipitation during curing and to prevent non-uniformity. Can be increased.

  The content ratio (parts by mass) of the [C3] thermoplastic resin in the [C] thermosetting resin composition of the present invention is preferably thermoplastic among the total 100 parts by mass of the [C] thermosetting resin composition. The resin content is 2 to 40 parts by mass, more preferably 2 to 25 parts by mass. [C3] When the content of the thermoplastic resin is too large, the viscosity of the resin composition increases, which may impair the processability and handleability of the resin composition and the prepreg, or [C2] the core-shell rubber particles [ C] There is a case where the microcracks are not sufficiently suppressed because they are not well dispersed in the thermosetting resin composition. [C2] In order for the core-shell rubber particles to be more satisfactorily dispersed in the [C] thermosetting resin composition, the content ratio (parts by mass) of [C3] thermoplastic resin is [C] thermosetting resin. Of the total 100 parts by mass of the composition, the thermoplastic resin content is preferably 2 to 15 parts by mass, more preferably 2 to 8 parts by mass. [C2] When the core-shell rubber particles are further satisfactorily dispersed in the [C] thermosetting resin composition, [C3] a high microcrack resistance can be expressed while the content ratio of the thermoplastic resin is small. .

  The ratio of the content ratio (parts by mass) of [C2] core-shell rubber particles in the [C] thermosetting resin composition of the present invention to the content ratio (parts by mass) of [C3] thermoplastic resin is [C] heat From the viewpoint of dispersibility of [C2] core-shell rubber particles in the curable resin composition, it is preferably in the range of 0.2: 1 to 5: 1, and more preferably in the range of 0.3: 1 to 5: 1. And particularly preferably in the range of 1: 1 to 5: 1. [C2] Inclusion of [C3] thermoplastic resin in thermosetting resin composition by controlling the ratio of the content ratio of [C2] core-shell rubber particles and the content ratio of [C3] thermoplastic resin to the above range The ratio and the content ratio of [C2] core-shell rubber particles are optimized, and the dispersibility of [C2] core-shell rubber particles can be further improved. Particularly, the content ratio of [C2] core-shell rubber particles is 1 to 10 parts by mass in 100 parts by mass of [C] thermosetting resin composition, and the content ratio (parts by mass) of [C3] thermoplastic resin. In the range of 2 to 8 parts by mass, it is more preferable from the viewpoint of dispersibility to make the content ratio described above. As a result, the obtained fiber reinforced composite material can highly balance both high microcrack resistance and high tensile strength.

  The [C] thermosetting resin composition in the prepreg of the present invention contains a curing agent component or a curing catalyst in order to cure the contained [C1] thermosetting resin by heat or external energy such as light or electron beam. Ingredients can be included. Depending on the type and application of the thermosetting resin used, and the usage environment, the type of thermosetting resin and the curing agent or curing catalyst can be selected as appropriate. From the viewpoints of heat resistance, chemical resistance, mechanical properties, and adhesion to carbon fiber, [C1] an epoxy resin is preferably used as the thermosetting resin, and therefore the epoxy resin curing agent or epoxy resin is used as the curing agent component. The curing catalyst is preferably used.

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

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

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

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

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

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

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

  [C] The thermosetting resin composition in the prepreg of the present invention preferably has a modulus of elasticity of 2.5 to 4.5 GPa of a cured resin obtained by curing. More preferably, it is 2.9 GPa to 4.5 GPa. When the elastic modulus is smaller than 2.5 GPa, the compressive strength of the fiber reinforced composite material may be lowered. When the flexural modulus exceeds 4.5 GPa, when the fiber reinforced composite material is used, the residual thermal stress generated by the temperature change becomes large, and the interface separation between the carbon fiber and the matrix resin occurs, resulting in sufficient microcracks. It may not be possible to suppress it.

In addition, the matrix resin is required to have a high fracture toughness value in order to suppress microcracks originating from thermal strain or interfacial delamination due to thermal cycling, and to prevent the development when microcracks occur. . Specifically, the stress intensity factor K1c in the opening mode of the cured resin obtained by curing is preferably 0.65 to 1.5 MPa · m ^1/2 . When K1c is less than 0.65 MPa · m ^1/2 , generation of microcracks due to thermal cycling may not be sufficiently suppressed. Moreover, when exceeding 1.5 Mpa * m1 / ² , the elastic modulus may fall.

  In addition, the resin cured product obtained by curing the thermosetting resin composition in the present invention is preferably one cured at a curing temperature of 120 to 200 ° C. for a curing time of 1 to 12 hours. . It is necessary to set the temperature rising time and the heat removal method appropriately so that the temperature of the resin at the time of curing falls within this temperature range. In addition, it is desirable that the degree of cure of the obtained cured product exceeds 80%. Here, the degree of cure means that the calorific value of the cured product and the uncured resin composition is evaluated by differential scanning calorimetry at a heating rate of 10 ° C./min in an inert gas atmosphere, and is 100 ° C. to 300 ° C. The area of the peak appearing at ° C. is calculated as the amount of heat generated by curing the resin composition, and {(heat value of the uncured resin composition) − (heat value of the cured product)} / (heat value of the uncured resin composition) ) × 100% is a value calculated according to the equation. When the degree of cure exceeds 80%, the calorific value of the cured resin varies depending on the calorific value of the uncured resin, but when it contains a trifunctional or higher amine type epoxy resin, the calorific value of the cured product ( The guideline is that it may be expressed as a residual calorific value) of 70 J / g or less.

  In addition, in order to improve the viscoelasticity of the uncured resin and the toughness of the cured resin, the [C] thermosetting resin composition in the prepreg of the present invention, in addition to the aforementioned core-shell rubber particles and thermoplastic resin, Various modifiers can be added as long as the effects of the present invention are not hindered. Specifically, organic particles such as thermoplastic resin particles and thermosetting resin particles can be blended.

  As the thermoplastic resin particles, polyamide particles and polyimide particles are preferably used. As commercial products of polyamide particles, “Amilan (registered trademark)” SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80 (manufactured by Toray Industries, Inc.), “Orgasol ( Registered trademark) "1002D, 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D (manufactured by Arkema Co., Ltd.) and the like can be used. As the shape of the particles, an appropriate form such as a spherical shape or an indefinite shape can be used depending on the purpose and purpose. Some of these thermoplastic resin particles exhibit a higher modification effect by not being dissolved in the matrix resin component during the curing process. Not dissolving during the curing process is also effective in improving the impregnation property while maintaining the fluidity of the resin at the time of curing.

  In the present invention, organic particles such as thermoplastic resin particles are blended in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the total epoxy resin composition in terms of achieving both the elastic modulus and toughness of the resulting cured resin. It is preferable that 1 to 15 parts by mass can be blended.

  In addition, the thermosetting resin composition of the present invention is an inorganic material such as a coupling agent, thermosetting resin particles, silica gel, carbon black, clay, carbon nanotube, and metal powder as long as the effects of the present invention are not hindered. Particles, inorganic fillers and the like can be blended.

  [C] The method for producing the thermosetting resin composition used in the present invention is composed of particle components such as core-shell rubber particles and thermoplastic resin particles, and constituent components other than the epoxy resin curing agent and curing catalyst at 140 to 170 ° C. After heating and kneading at a certain temperature to dissolve and homogenize the thermoplastic resin, the mixture is then cooled to 110 ° C. or lower and the core-shell rubber particles or the master batch in which the core-shell rubber particles are uniformly dispersed is added and heated and kneaded uniformly. Then, after cooling to a temperature of about 80 ° C., it is preferable to add particle components such as thermoplastic resin particles, a curing agent or a curing catalyst component, and knead. When the core-shell rubber particles are dispersed and blended and mixed and kneaded with other components such as a curing agent after the dispersion, it is preferably performed within a temperature and viscosity range in which re-aggregation of the core-shell rubber particles does not occur. Specifically, depending on the composition, for example, when kneaded at a temperature of 150 ° C. or higher, the viscosity of the composition may decrease and aggregation may occur. The case where the temperature reaches 150 ° C. or higher in the process is not limited to this, because re-aggregation is hindered due to gelation when the temperature is raised. [C3] As a method of dissolving the thermoplastic resin in [C1], in addition to the method of dissolving by heating as described above, a method in which a thermoplastic resin is dissolved in a solvent such as acetone, methyl ethyl ketone, and toluene [ A method of distilling the solvent after mixing with the thermosetting resin of C1] and making it uniform can also be used. However, the blending method of each component is not particularly limited to these methods.

  [C] The kneading method of the thermosetting resin composition used in the present invention may be any method generally used for preparing a thermosetting resin composition. For example, a kneader, a planetary mixer, or a three roll is used.

  [A] A mesh or non-woven fabric composed of a biaxial or higher carbon fiber woven fabric and [B] [B1] metal wire, or [B2] metal wire in combination with [C] a thermosetting resin composition, to form the prepreg of the present invention. As a manufacturing method, in addition to the method of impregnating [C] into a base material in which [A] and [B] are combined in advance, [A] is impregnated with the thermosetting resin composition of [C]. A method of attaching [B] to a material or a method of manufacturing by pressing [B] between [A] and impregnating the thermosetting resin composition of [C], pressurizing and heating, etc. is used. be able to. Further, a method of preliminarily impregnating [B] with the thermosetting resin composition [C] to form a sheet and sticking it to the carbon fiber fabric of [A] can also be used. Attaching to [A] or [A] impregnated with [C] or using [C] in the form of a film while applying appropriate tension to [B] using a drum winding method or the like. [B] [B1] mesh or non-woven fabric made of metal wire, or [B2] metal wire without meandering or disarray, especially [B2] [B2] conductive wire It is effective when using.

  [A] A carbon fiber bundle in which [B2] of the present invention is [A] by combining a biaxial or more carbon fiber woven fabric and [B2] metal wire with a thermosetting resin composition containing [C] core-shell rubber particles. As a method for producing a prepreg having a configuration arranged on the side surface of [A], a base material combining [A] biaxial or higher carbon fiber fabric and [B2] metal wire (for example, a base material described in JP-A-2006-265769) And the like can be impregnated with an epoxy resin.

  In the prepreg of the present invention, [A] a biaxial or more carbon fiber woven fabric, [B] [B1] a mesh or nonwoven fabric made of a metal wire, or [B2] a metal wire, or a group made of [A] and [B]. As a method of impregnating the material with the thermosetting resin composition of [C], a wet method in which [C] is dissolved in a solvent such as methyl ethyl ketone or methanol to lower the viscosity and impregnate the reinforcing fiber substrate, A hot melt method or the like in which the viscosity of C] is reduced by heating and impregnated into the reinforcing fiber substrate can be suitably used.

  The wet method is a method of obtaining a prepreg by immersing a reinforcing fiber in a solution of a thermosetting resin composition and then evaporating the solvent using an oven or the like to evaporate the solvent.

  The hot melt method is a method of directly impregnating reinforcing fibers with a thermosetting resin composition whose viscosity has been reduced by heating, or a resin film in which a thermosetting resin composition is coated on release paper or the like, Next, the resin film is overlapped from both sides or one side of the reinforcing fiber and heated and pressed to impregnate the thermosetting resin composition to obtain a prepreg. This hot melt method is a preferred method because substantially no solvent remains in the prepreg. The temperature at which the resin film is produced depends on the viscoelasticity of the resin, but a temperature of about room temperature to 100 ° C. is suitable. From the viewpoint of producing a film having a stable thickness, it is preferable that the change in the viscosity of the resin is small at the temperature at which this film is produced. For example, it is preferable that the change in complex viscoelasticity η * measured at a constant temperature for 2 hours at a temperature at which a film is produced using a dynamic viscoelasticity device does not change or is not more than twice even when the viscosity is increased. In other words, the film should be produced at a temperature that is twice or less even if the viscosity is increased.

The basis weight of the resin film is 15 to 200 g / m ^{2 although} it varies depending on the intended use. If the basis weight of the film is less than 15 g / m ² , it is difficult to obtain a technically stable basis weight. Moreover, when it is 200 g / m ² or more, when it is impregnated by transfer under pressure, it may protrude from the reinforcing fiber, and a stable product may not be produced.

  In addition, the prepreg of the present invention includes [A] biaxial or higher carbon fiber woven fabric, [B] [B1] mesh or nonwoven fabric made of metal wire, or [B2] metal wire or [A] biaxial or higher carbon fiber. [C] The thermosetting resin composition may be completely impregnated or may have an unimpregnated portion on the base material composed of a woven fabric and [B2] metal wire (hereinafter referred to as partial impregnation). Sometimes). By having the part which is not impregnated, it may become effective for suppression of the void at the time of shaping | molding.

  Further, the fiber-reinforced composite material of the present invention is obtained by laminating one or a plurality of prepregs produced by such a method, and then heat-curing an epoxy resin while applying heat and pressure to the obtained laminate. Can be manufactured.

  As a method for applying heat and pressure, 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 used. In particular, an autoclave molding method is preferably used for aircraft member molding, and a wrapping tape method and an internal pressure molding method are preferably used for sports equipment molding.

  The conditions for molding the prepreg of the present invention using an autoclave are appropriately set according to the viscoelasticity, number of layers, size, etc. of the prepreg, and Tg of the fiber-reinforced composite material after curing. And a pressure range of 0.1 to 1 MPa and a curing temperature of 120 to 200 ° C. are preferably used. In particular, a pressure of 0.3 to 0.7 MPa and a curing temperature of 170 to 190 ° C. are more preferably used. When raising the temperature from room temperature to the curing temperature, the temperature may be increased to a curing temperature at a constant rate, or may be maintained for a certain period of time at an intermediate temperature, and then increased to the curing temperature (hereinafter referred to as this). A curing method using a stepwise temperature rising method is sometimes referred to as step cure). When molding large structures, even if the temperature is set at a constant rate, uneven temperature increases may occur in the large autoclave. There is a possibility that unexpected physical property change or runaway reaction may occur, or that the resin flow time is insufficient with respect to the size of the structure, resulting in poor impregnation of the resin into the fibers. In order to solve such problems, step cure as described above may be used effectively. In order to improve the impregnation property of the resin into the fiber, the partially impregnated prepreg as described above can also be used. When the pressure at the time of molding is too low, many voids are generated in the fiber-reinforced composite material after molding, which may be the starting point of microcracks. Therefore, it is preferable to set appropriate conditions according to the prepreg to be used. In addition, it is necessary to appropriately select materials that can withstand the molding conditions to be applied as materials used for autoclave molding.

  The wrapping tape method is a method in which a prepreg is wound around a mandrel or the like and a tubular body made of a fiber reinforced composite material is formed, and is a suitable method for producing a rod-like body such as a golf shaft or a fishing rod. . More specifically, after winding the prepreg on a mandrel, winding a wrapping tape made of a thermoplastic resin film on the outside of the prepreg for fixing and applying pressure, and heat curing the epoxy resin in an oven, In this method, the core is removed to obtain a tubular body.

  In addition, the internal pressure molding method is to set a preform in which a prepreg is wound on an internal pressure applying body such as a tube made of a thermoplastic resin in a mold, and then apply high pressure gas to the internal pressure applying body to apply pressure. At the same time, the mold is heated to form a tubular body. This internal pressure molding method is particularly preferably used when molding a complicated shape such as a golf shaft, a bat, and a racket such as tennis or badminton.

  In the carbon fiber reinforced composite material of the present invention, a mesh, a nonwoven fabric, or a metal wire made of the metal wire [B] appears in a cross section cut in a direction perpendicular to the surface. The carbon fiber reinforced composite material of the present invention is processed so that the mesh, nonwoven fabric, or metal wire made of the metal wire of [B] appears on the end surface, and the end surface is brought into contact with a metal member, conductive paste, metal fastener, or the like. Thus, when an electric current is generated in the carbon fiber reinforced composite material, it can be efficiently diffused out of the system. When the carbon fiber reinforced composite material of the present invention is used, for example, on the surface of an aircraft fuselage, wing, automobile body, etc., and the end face is brought into contact with a metal fastener, a metal plate, etc., the current flowing due to lightning strikes etc. Since it is diffused out of the structure from the metal part that passes through, it is possible to prevent current from flowing into the fuel in the cabin or wing of the aircraft fuselage, or in the car.

  The fiber-reinforced composite material of the present invention is used for aircraft structural members, windmill blades, automobile outer plates, IC trays and notebook PC cases (housings), building materials, and sports applications such as golf shafts and tennis rackets. Can be preferably used. It can be particularly preferably used in applications exposed to natural environments such as lightning strikes and temperature changes, such as transportation equipment and outdoor structural materials.

Hereinafter, the prepreg and the fiber-reinforced composite material of the present invention will be described more specifically with reference to examples. Here, Examples 3 to 8, 16 , and 17 are examples of the present invention, and Examples 1, 2, 9 to 15 , and 18 to 20 are reference examples. Resin raw materials, prepregs and fiber reinforced composite materials used in the examples, methods for evaluating the elastic modulus and fracture toughness of the cured resin (K1c evaluation method), methods for evaluating the tensile strength and compressive strength of the fiber reinforced composite materials, micro The evaluation method of crack resistance is shown below. Various evaluations of the examples and the prepreg production environment were performed in an atmosphere of a temperature of 25 ° C. ± 2 ° C. and a relative humidity of 50% unless otherwise specified.

(1) [A] Carbon fiber fabric used in Examples, [B] Mesh made of metal wire, and [C] Raw material of thermosetting resin <Carbon fiber fabric> ([A])
The following carbon fiber is used for both warp and weft, and a plain weave with a carbon fiber basis weight (weight per square meter) of 196 ± 5 g / m ² .

  Polyacrylonitrile (PAN) carbon fiber manufactured by Toray Industries, Inc .: 6,000 filaments, fineness 223 tex, tensile strength 5.5 GPa, tensile modulus 294 GPa.

<Mesh made of metal wire> ([B])
The following metal wires are arranged in a grid with a basis weight of 28 g / m ² .

  Phosphor bronze wire manufactured by Mie Wire Industry Co., Ltd., standard JIS H-3270, wire diameter 0.1 mm.

<Epoxy resin> ([C1] thermosetting resin)
ELM434 (tetraglycidyldiaminodiphenylmethane, epoxy equivalent: 120, manufactured by Sumitomo Chemical Co., Ltd.) (trifunctional or higher functional epoxy resin)
"Araldite (registered trademark)" MY721 (tetraglycidyldiaminodiphenylmethane, epoxy equivalent: 113, manufactured by Huntsman Advanced Materials (hereinafter referred to as Huntsman))
"Araldite (registered trademark)" MY0600 (triglycidyl-m-aminophenol, epoxy equivalent: 118, manufactured by Huntsman) (tri- or higher functional epoxy resin)
"Epiclon (registered trademark)" 830 (bisphenol F type epoxy resin, epoxy equivalent: 172, manufactured by DIC Corporation)
GAN (N, N-diglycidyl aniline, epoxy equivalent: 125, manufactured by Nippon Kayaku Co., Ltd.)
GOT (N, N-diglycidyl-o-toluidine, epoxy equivalent: 135, manufactured by Nippon Kayaku Co., Ltd.)
OPP-G (o-phenylphenyl glycidyl ether, epoxy equivalent: 226, manufactured by Sanko Co., Ltd.).

<Core shell rubber particles> (master batch in which [C2] is dispersed in a part of [C1])
"Kaneace (registered trademark)" MX416 (tetraglycidyl diaminodiphenylmethane ("Araldite (registered trademark)" MY721) manufactured by Huntsman Co., Ltd.): 75% by mass / core shell rubber particles (volume average particle size: 100 nm, core portion: crosslinked polybutadiene [Tg : -70 ° C], shell portion: methyl methacrylate / glycidyl methacrylate / styrene copolymer): 25% by mass masterbatch, epoxy equivalent: 150, manufactured by Kaneka Corporation)
“Kane Ace (registered trademark)” MX136 (bisphenol F type epoxy resin (“Araldite (registered trademark)” GY285) manufactured by Huntsman Co., Ltd.): 75% by mass / core shell rubber particles (volume average particle size: 100 nm, core portion: crosslinked polybutadiene [ Tg: −70 ° C.], shell portion: methyl methacrylate / glycidyl methacrylate / styrene copolymer): 25% by mass master batch, epoxy equivalent: 220, manufactured by Kaneka Corporation).

<Solid rubber having reactive ends> (masterbatch dispersed in some components of [C1])
"HyPox (registered trademark)" RA95 (bisphenol A type epoxy resin: 93 to 95% by mass / elastomer modified bisphenol A type epoxy resin (addition product of carboxyl-terminated acrylonitrile butadiene copolymer and bisphenol A type epoxy resin): 5 to 5 7% by mass master batch, epoxy equivalent: 202, manufactured by CVC Thermoset Specialties).

<Thermoplastic resin soluble in thermosetting resin> ([C3])
・ "Sumika Excel (registered trademark)" PES5003P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.)
"Ultem (registered trademark)" 1010 (polyetherimide, manufactured by SABIC Innovative Plastics))
<Curing agent>
"Seika Cure (registered trademark)"-S (4,4'-diaminodiphenyl sulfone, melting point 177 ° C., manufactured by Wakayama Seika Kogyo Co., Ltd.)
3,3′-DAS (3,3′-diaminodiphenyl sulfone, melting point 172 ° C., manufactured by Mitsui Chemicals Fine Co., Ltd.).

<Thermoplastic resin particles>
"Amilan (registered trademark)" SP-500 (polyamide fine particles mainly composed of nylon 12, manufactured by Toray Industries, Inc.), average particle diameter 5 μm.
"Orgasol (registered trademark)" 1002DNAT1 (nylon 6 fine particles, manufactured by Arkema), average particle size 20 μm
Particle A (particles having an average particle diameter of 18.0 μm, made from “Grillamide (registered trademark)” TR-55 manufactured by Mzavelke Co., Ltd.)
(Method for producing particle A)
Polyamide containing 4,4′-diamino-3,3′dimethyldicyclohexylmethane as an essential component (“Milamide (registered trademark)” TR-55 manufactured by Mzavelke Co., Ltd.), 94 parts by weight, epoxy resin (Mitsubishi Chemical Corporation) ) "JER (registered trademark)" 828) 4 parts by weight and a curing agent (Fuji Kasei Kogyo "Tomide (registered trademark)"# 296) 2 parts by weight chloroform 300 parts by weight methanol 100 parts by weight It added in the mixed solvent and obtained the uniform solution. Next, the solution was atomized using a spray gun for coating, and sprayed toward the liquid surface of 3000 parts by weight of n-hexane, which was well stirred, to precipitate a solute. The precipitated solid is separated by filtration, washed well with n-hexane, vacuum dried at 100 ° C. for 24 hours, and further, a small particle component and a large component are removed using a sieve, respectively. Uniform transparent polyamide particles were obtained. When the obtained powder was observed with a scanning electron microscope, it was polyamide fine particles having an average particle diameter of 18.0 μm.
Particle B (“Trogamide (registered trademark)” CX7323 as a raw material and having an average particle diameter of 13 μm)
(Production method of particle B: International Publication No. 2009/142231 pamphlet was used as reference)
In a 1000 ml pressure-resistant glass autoclave (pressure-resistant glass industry, Hyper Glaster TEM-V1000N), 35 g of polyamide (weight average molecular weight 17,000, “TROGAMID (registered trademark)” CX7323) manufactured by Degussa as an organic polymer A 287 g of N-methyl-2-pyrrolidone as a solvent, 28 g of polyvinyl alcohol as polymer B (“GOHSENOL (registered trademark)” GM-14 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Weight average molecular weight 29,000, sodium acetate content 0.23 mass %, SP value 32.8 (J / cm ³ ) ^1/2 ) was added, and 99% by volume or more of nitrogen was substituted, and then heated to 180 ° C. and stirred for 2 hours until the polymer was dissolved. Thereafter, 350 g of ion-exchanged water as a poor solvent was dropped at a speed of 2.92 g / min via a liquid feed pump. When about 200 g of ion exchange water was added, the system turned white. After the entire amount of water has been added, the temperature is lowered while stirring, and the resulting suspension is filtered, washed with 700 g of ion-exchanged water, reslurried, and filtered, and vacuum-dried at 80 ° C. for 10 hours. And 34 g of a gray colored solid were obtained. When the obtained powder was observed with a scanning electron microscope, it was polyamide fine particles having an average particle diameter of 13 μm.
Particle C (particles having an average particle diameter of 15.3 μm, produced from “Grillamide (registered trademark)” TR90 as a raw material)
(Manufacturing method of particle C: Reference was made to the pamphlet of International Publication No. 2009/142231)
In a 100 ml four-necked flask, 2.1 g of amorphous polyamide (weight average molecular weight 12,300, “Grilamide (registered trademark)” TR90, manufactured by Mzavelke) as polymer A, and formic acid (Wako Pure Chemical Industries, Ltd.) as an organic solvent 25.8 g, polyvinyl alcohol 2.1 g (Nippon Synthetic Chemical Industry Co., Ltd. “GOHSENOL (registered trademark)” GM-14, weight average molecular weight 22,000, SP value 32.8 (J / cm ³⁾ ) ^1/2 ) was added, heated to 80 ° C., and stirred until the polymer was dissolved. After the temperature of the system was lowered to 40 ° C., 60 g of ion-exchanged water as a poor solvent was dropped at a speed of 0.05 g / min via a liquid feed pump while stirring at 900 rpm. The solution was dropped while gradually increasing the dropping speed, and the entire amount was dropped over 90 minutes. The system turned white when 10 g of ion exchange water was added. When half the amount of ion-exchanged water was dropped, the temperature of the system was raised to 60 ° C., then the remaining ion-exchanged water was added, and after the whole amount was dropped, stirring was continued for 30 minutes. The suspension returned to room temperature was filtered, washed with 50 g of ion exchange water, and vacuum dried at 80 ° C. for 10 hours to obtain 2.0 g of a white solid. When the obtained powder was observed with a scanning electron microscope, it was polyamide fine particles having an average particle size of 15.3 μm.

  The average particle diameter of the resin particles was calculated by measuring the diameter of 100 arbitrary particles from a photograph and obtaining the arithmetic average thereof. The average particle diameter here refers to the number average particle diameter. The individual particle diameter of the resin particles was measured by observing the fine particles at 1000 times with a scanning electron microscope (JSM-6301NF, manufactured by JEOL Ltd.). When the particles were not perfect circles, the major axis was measured as the particle diameter.

  In addition, it was determined as follows that the thermoplastic resin PES5003P used in this example is soluble in the [C1] thermosetting resin. That is, for a mixture of 100 parts by mass of the ELM434 (one of [C1]) and 5 parts by mass of the PES5003P, a parallel plate having a diameter of 40 mm is used using a dynamic viscoelasticity measuring apparatus (ARES manufactured by TA Instruments). Then, a change in viscosity at 100 ° C. for 2 hours was measured under the conditions of a frequency of 0.5 Hz and a parallel plate interval of 1 mm. At this time, the viscosity increased by 40% in 2 hours. When the viscosity change at 100 ° C. for 2 hours of ELM434 alone was measured in the same manner, the viscosity change was 5% or less. From these results, it was determined that the mixture of PES5003P changed substantially in viscosity at 100 ° C. for 2 hours, that is, PES5003P was soluble in the thermosetting resin ELM434. Polyethersulfone has a melting point of about 400 ° C. and a glass transition temperature of about 190 ° C. Similarly, it was determined that the polyetherimide also has a property soluble in the thermosetting resin ELM434. The glass transition temperature of polyetherimide is about 215 ° C. Moreover, it confirmed that it melt | dissolved uniformly also in the preparation process of the resin composition mentioned later.

(2) Preparation of thermosetting resin composition [Examples 1 to 20]
A thermoplastic resin soluble in an epoxy resin and a thermosetting resin was heated and mixed at 150 ° C. and uniformly dissolved, then cooled to 110 ° C., and a master batch of core-shell rubber particles was added and kneaded. After cooling to 80 ° C. or lower, thermoplastic resin particles were added and kneaded, and then a curing agent was added and kneaded to prepare epoxy resin compositions having the compositions shown in Tables 1 and 2. In addition, the value of the resin composition in Table 1, 2 shows a mass part.

[Comparative Example 1]
After the epoxy resin was uniformly kneaded at 110 ° C., a master batch of core-shell rubber particles was added and kneaded. After cooling this to 80 degrees C or less, the hardening | curing agent was then added and knead | mixed and the epoxy resin composition of the composition shown in Table 3 was prepared. In addition, the value of the resin composition in Table 3 indicates parts by mass.

[Comparative Examples 2 to 4]
An epoxy resin, a thermoplastic resin soluble in a thermosetting resin (Comparative Examples 2 and 3), and HyPox RA95 (Comparative Example 4) are heated and mixed at 150 ° C. and uniformly dissolved, and then cooled to 80 ° C. or lower. Organic particles were added and kneaded (Comparative Examples 2 and 3), and then a curing agent was added and kneaded to prepare an epoxy resin composition having the composition shown in Table 3. In addition, the value of the resin composition in Table 3 indicates parts by mass.

(3) Method of measuring flexural modulus of cured resin product After defoaming the resin composition prepared by the method of (2) in a vacuum, the thickness is 2 mm with a 2 mm thick “Teflon (registered trademark)” spacer. And cured at a temperature of 180 ° C. for 2 hours to obtain a cured resin product having a thickness of 2 mm. From this, a test piece having a width of 10 mm and a length of 55 mm was cut out, an Instron universal testing machine was used, the span length was 32 mm, the crosshead speed was 2.5 mm / min, and three-point bending was performed according to JIS K7171 (1999). A flexural modulus was obtained. The number of samples was set to n = 5, and the average value was compared.

(4) Fracture toughness test (K1c evaluation) method of cured resin product After defoaming the resin composition prepared by the method of (2) in a vacuum, the thickness is 6 mm using a 6 mm thick “Teflon (registered trademark)” spacer. And cured for 2 hours at a temperature of 180 ° C. in a mold set so as to obtain a cured resin product having a thickness of 6 mm. This cured resin was cut at 12.7 × 150 mm to obtain a test piece. Using an Instron universal testing machine, test pieces were processed and tested according to ASTM D5045. The initial cracking was introduced into the test piece by applying a razor blade cooled to the liquid nitrogen temperature to the test piece and impacting the razor with a hammer. The fracture toughness of the cured resin here is evaluated by the critical stress strength in deformation mode 1 (opening type).

(5) Preparation method of prepreg The resin composition prepared by the method of (2) was applied onto release paper using a knife coater to prepare a resin film. [A] [B] Conductive mesh is placed and combined on one side of the carbon fiber fabric, resin films are stacked from both sides, and the resin is impregnated by heat and pressure, and [A] and [B] are thermoset. A prepreg made of a conductive resin composition was prepared. Similarly, [A] carbon fiber fabrics were laminated with resin films from both sides and impregnated with resin by heating and pressing to prepare a prepreg composed of [A] and a thermosetting resin composition. The resin content of these prepregs is such that the mass fraction of the matrix resin is 40% by mass, assuming that the total weight of the thermosetting resin composition [A] carbon fiber fabric and matrix resin is 100% by mass. Created to be.

(6) Compressive strength test in the warp direction of the fiber reinforced composite material The prepreg prepared by the method of (5) was cut into a size of 150 × 150 mm, and 14 layers were laminated in the warp direction. This was vacuum bagged and cured for 2 hours at a temperature of 180 ° C. and a pressure of 0.61 Pa using an autoclave to obtain a test material. A fiber reinforced composite material (which does not contain [B] conductive mesh) made in the same manner was cut into 45 × 150 mm pieces to create a tab. This tab was bonded to an adhesive film for curing at 130 ° C. Using two sheets on one side, they were laminated to the test material so that the distance between the tabs was 4.77 mm at the same position on both sides, and the adhesive film was cured by heating at a temperature of 130 ° C. and a pressure of 3 atm for 1 hour. The test material was cut according to JIS K7076 (1991) to prepare a test piece. The compressive strength in the warp direction of the test piece was measured at a crosshead speed of 1.27 mm / min using an Instron universal testing machine.

(7) Tensile strength test in the warp direction of fiber reinforced composite material Cut the prepreg prepared by the method of (5) into a predetermined size, laminate 14 sheets in the warp direction, perform a vacuum bag, and use an autoclave And cured at a temperature of 180 ° C. and a pressure of 6 atm for 2 hours to obtain a fiber-reinforced composite material. This unidirectional reinforcing material was cut with a width of 25.4 mm and a length of 230 mm, and processed into a dumbbell shape with a center of 12.7 mm, to obtain a test piece. Using an Instron universal tester, the tensile strength in the warp direction of the test piece was measured at a crosshead speed of 1.27 mm / min.

(8) Microcrack resistance evaluation method of fiber reinforced composite material The prepreg prepared by the method of (5) is cut into a predetermined size, the warp direction of the carbon fiber fabric is defined as 0 °, and [± 45/0 / ± 45/90 °] was repeated twice and the layers were stacked symmetrically (total of 16 layers). This was vacuum bagged and cured for 2 hours at a temperature of 180 ° C. and a pressure of 6 atmospheres using an autoclave to obtain a fiber reinforced composite material plate.

The obtained fiber-reinforced composite material plate was cut into a size of 75 mm × 50 mm with a diamond cutter to obtain a test piece. The test piece was exposed to environmental conditions as shown in the following procedures a, b, and c using a commercially available constant temperature and humidity chamber and an environmental test machine.
a. The sample is exposed to an environment of 49 ° C. and 95% relative humidity for 12 hours using a commercially available thermostatic chamber.
b. After exposure, the sample is transferred to a commercially available environmental testing machine, and exposed to an environment of -54 ° C for 1 hour. Thereafter, the temperature is raised to 71 ° C. at a temperature rising rate of 10 ° C. ± 2 ° C./min. After the temperature rise, hold at 71 ° C. for 5 minutes ± 1 minute, lower the temperature to −54 ° C. at 10 ° C. ± 2 ° C./minute, and hold at −54 ° C. for 5 minutes ± 1 minute. A cycle in which the temperature is raised from -54 ° C to 71 ° C and lowered to -54 ° C is defined as one cycle, and this cycle is repeated 200 times.
c. The above-mentioned environmental exposure in the constant temperature and humidity chamber and the cycle in the environmental testing machine are defined as 1 block, and 5 blocks are repeated.

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

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

  Examples 1 to 20 had good microcrack resistance in any of the fiber reinforced composite materials including only the carbon fiber woven fabric and conductive mesh. In addition, excellent compressive strength and tensile strength were exhibited.

  On the other hand, Comparative Example 1 is an example that does not contain a thermoplastic resin that is soluble in the thermosetting resin, and the fiber-reinforced composite material containing only carbon fibers showed good microcrack resistance, but has electrical conductivity. The fiber reinforced composite material including the mesh was slightly inferior in microcrack resistance. Moreover, although compressive strength was favorable, it was inferior to tensile strength.

  Comparative Examples 2 and 3 were systems that did not contain core-shell rubber particles and were inferior in microcrack resistance. In addition, the mechanical properties (tensile strength) of the fiber reinforced composite material were not sufficiently developed.

  Comparative Example 4 is a system in which a solid rubber component is blended in place of the core-shell rubber particles. Microcrack resistance was expressed as well as in the examples containing the core-shell rubber particles, but the flexural modulus of the cured resin was slightly low, and the mechanical properties (tensile strength) of the fiber reinforced composite material were not fully expressed. It was.

(A) [B1] Mesh made of metal wire, metal wire constituting non-woven fabric, or [B2] metal wire (a schematic representation of the longitudinal direction of the fiber)
(B) [B1] Mesh made of metal wire, metal wire constituting the nonwoven fabric, or [B2] metal wire (representing the fiber cross section schematically)
(C) [A] Carbon fiber fabric layer (d) [A] Carbon fiber bundles constituting the carbon fiber fabric

Claims (13)

A prepreg comprising at least the following [A], [B], and [C], wherein [B] is arranged on one side or both sides of [A].
[A] Biaxial or more carbon fiber woven fabric [B] [B1] Mesh or nonwoven fabric made of metal wire, and [B2] At least one selected from metal wire [C] At least [C1] thermosetting resin, [C2 ] A thermosetting resin composition comprising core-shell rubber particles, [C3] a thermoplastic resin soluble in the [C1] thermosetting resin, and [C1] the thermosetting resin is an epoxy having three or more functions. Resin and glycidyl aniline type epoxy resin or monofunctional epoxy resin, [C3] the thermoplastic resin is polyethersulfone, [C] in 100 parts by mass of the thermosetting resin composition, [C2] core shell 1-10 parts by weight rubber particles, [C3] thermoplastic resin is contained 8 parts 2, and, [C2] content of the core-shell rubber particles (parts by mass) [C3] of the thermoplastic resin containing The ratio between the ratio (parts by weight) is 0.321: 1 to 0.714: 1 range der Ru thermosetting resin composition A prepreg that includes at least the following [A], [B2], and [C], and has a configuration in which [B2] is disposed on the side surface of the carbon fiber bundle of [A].
[A] Biaxial or more carbon fiber fabric [B2] Metal wire [C] At least [C1] thermosetting resin, [C2] core shell rubber particles, [C3] Heat soluble in [C1] thermosetting resin [C1] The thermosetting resin includes a trifunctional or higher functional epoxy resin and a glycidyl aniline type epoxy resin or a monofunctional epoxy resin, and [C3]. The thermoplastic resin is polyethersulfone, and [C] 1 to 10 parts by mass of [C2] core shell rubber particles, and [C3] 2 to 8 parts by mass of the thermoplastic resin in 100 parts by mass of the thermosetting resin composition. And the ratio of the content ratio (parts by mass) of [C2] core-shell rubber particles to the content ratio (parts by mass) of [C3] thermoplastic resin is 0.321: 1 to 0.714: 1. range der of Ru thermosetting resin sets Thing [A] The prepreg according to claim 1 or 2, wherein the carbon fibers used in the biaxial or higher carbon fiber fabric are carbon fibers having a tensile elastic modulus of 270 GPa or more in a strand tensile test. [A] The carbon fiber woven fabric having two or more axes is a carbon fiber bundle (yarn) arranged in two directions of the warp direction and the weft direction. The prepreg as described. [A] The prepreg according to any one of claims 1 to 4, wherein the biaxial or higher carbon fiber woven fabric is in a form selected from a plain weave, a twill weave, and a satin weave. The prepreg according to any one of claims 1 to 5, wherein a cover factor of the [A] biaxial or higher carbon fiber fabric is in a range of 90 to 100%. The prepreg according to any one of claims 1 to 6, wherein the [B1] metal wire comprises a mesh or a non-woven metal wire, or the [B2] metal wire has a diameter of 50 to 200 µm. [B1] The mesh or nonwoven fabric made of a metal wire, or [B2] metal wire is contained in an amount of 5 to 40 parts by mass with respect to 100 parts by mass of the [A] biaxial or higher carbon fiber fabric. The prepreg according to any one of 7 above. The prepreg according to any one of claims 1 to 8, wherein an elastic modulus of a cured resin obtained by curing the [C] thermosetting resin composition is 2.5 to 4.5 GPa. The prepreg according to any one of claims 1 to 9, wherein K1c of a cured resin obtained by curing the [C] thermosetting resin composition is 0.65 to 1.5 MPa · m ^1/2 . The prepreg according to any one of claims 1 to 10, wherein the [C] thermosetting resin composition contains an aromatic amine curing agent having a melting point of 50 ° C or higher. Fiber-reinforced composite material obtained by curing the prepreg according to any one of claims 1 to 11. At least said [A], [B], a process for the preparation of the resulting prepreg with [C], comprising the step of dissolving said [C3] to [C1], to any one of claims 1 to 11 The manufacturing method of prepreg of description.