Prepreg and method for producing prepreg

Abstract

This prepreg comprises a resin composition and a carbon nanotube film. The resin composition has infiltrated into the carbon nanotube film, comprises a radical-polymerization-type thermally curable oligomer and a polymerization initiator, and has an aromatic nucleus concentration of 0.1 mol / kg or higher. The basis weight of the carbon nanotube film is 0.0226-170 mg / cm2, and the carbon nanotube film is a stack of carbon-nanotube webs.

Description

Prepreg and method for manufacturing prepreg

[0001] This invention relates to prepregs and methods for producing prepregs.

[0002] Carbon nanotubes possess excellent heat resistance, mechanical properties, and conductivity, making them suitable raw materials for various industrial products requiring these qualities. In particular, composite materials obtained by combining carbon nanotubes with resins exhibit excellent moldability, and are therefore expected to have a wide range of applications as molded articles possessing the aforementioned properties. For example, their strength, light weight, and heat resistance make them suitable for use as exteriors and components in automobiles and airplanes, blades used in wind power generation, and sporting goods. For this reason, various studies and developments are being conducted on composite materials of carbon nanotubes and resins.

[0003] For example, Patent Document 1 discloses a carbon nanotube-containing resin composite obtained by impregnating a resin with an oriented carbon nanotube aggregate of a specific specific surface area, with the aim of increasing the carbon nanotube content and obtaining a resin composite that takes advantage of the anisotropy of carbon nanotubes.

[0004] International Publication No. 2008 / 133299

[0005] Although carbon nanotubes possess the excellent properties described above, they are difficult to composite with resins, and the inherent mechanical properties of carbon nanotubes cannot be imparted to the composite material, resulting in insufficient strength in the resulting composite material. Therefore, there has been a need for an intermediate material containing resin and carbon nanotubes that can be sufficiently composited with carbon nanotubes, bring out the mechanical properties of carbon nanotubes, and improve the strength of the resulting composite material. In particular, there has been a need for such an intermediate material in the form of a prepreg, which is a sheet-like molding material. Therefore, the object of the present invention is to provide a prepreg that has excellent strength in the resulting fiber-reinforced composite material.

[0006] The present inventors have found that a prepreg containing a resin composition with a specific aromatic kernel concentration and a carbon nanotube film which is a web laminate with a specific basis weight can solve the above problem. That is, the present invention relates to the following: [1] A prepreg containing a resin composition and a carbon nanotube film, wherein the resin composition is impregnated into the carbon nanotube film, the resin composition contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2[1] A prepreg wherein the carbon nanotube film is a carbon nanotube web laminate. [2] The prepreg according to [1], wherein the resin composition further contains a polymerizable monomer. [3] The prepreg according to [1] or [2], wherein the radical polymerization thermosetting oligomer is a urethane (meth)acrylate, and the urethane (meth)acrylate has structural units derived from a compound having two or more isocyanate groups and structural units derived from a hydroxyalkyl (meth)acrylate. [4] The prepreg according to any one of [1] to [3], wherein the carbon nanotube web consists of a plurality of carbon nanotube fibers, and the plurality of carbon nanotube fibers are aligned in the same direction. [5] The prepreg according to any one of [2] to [4], wherein the polymerizable monomer contains at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and ethoxylated-o-phenylphenol acrylate. [6] The prepreg according to any one of [3] to [5] above, wherein the acrylic equivalent of the radical polymerization-type thermosetting oligomer is 200 to 1600 g / eq. [7] The prepreg according to any one of [1] to [6] above, wherein the 10-hour half-life temperature of the polymerization initiator is 45 to 130°C. [8] The prepreg according to any one of [2] to [7] above, wherein the content of the polymerizable monomer in the resin composition is 1 to 60% by mass. [9] The prepreg according to any one of [3] to [8] above, wherein the compound having two or more isocyanate groups is an aromatic isocyanate compound.

[10] The prepreg according to any one of [1] to [9] above, wherein the aromatic kernel concentration of the resin composition is 1.0 to 3.0 mol / kg.

[11] A prepreg comprising a resin composition, a carbon nanotube film, and a carbon fiber sheet, wherein the resin composition is impregnated into the carbon nanotube film and the carbon fiber sheet, the resin composition contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2

[12] A prepreg wherein the carbon nanotube film is a carbon nanotube web laminate.

[13] A prepreg according to any one of [1] to

[11] above, wherein the viscosity of the resin composition at 80°C is 0.1 to 30 Pa·s.

[14] A fiber-reinforced composite molded article obtained by molding the prepreg according to any one of [1] to

[12] above.

[15] A method for producing a resin composition containing a radical polymerization thermosetting oligomer and a polymerization initiator, and a prepreg containing a carbon nanotube film, comprising the steps of impregnating the carbon nanotube film with the resin composition, or impregnating the carbon nanotube film with a liquid composition containing the raw materials for the radical polymerization thermosetting oligomer and the polymerization initiator, and aging at 30 to 90°C to obtain a resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 A method for producing a prepreg, wherein the carbon nanotube film is a carbon nanotube web laminate.

[15] A method for producing a prepreg comprising a resin composition containing a radical polymerization thermosetting oligomer and a polymerization initiator, a carbon nanotube film, and a carbon fiber sheet, comprising the steps of impregnating the carbon nanotube film and the carbon fiber sheet with the resin composition, or impregnating the carbon nanotube film and the carbon fiber sheet with a liquid composition containing the raw materials for the radical polymerization thermosetting oligomer and the polymerization initiator, and aging at 30 to 90°C to obtain a resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 A method for manufacturing a prepreg in which the carbon nanotube film is a carbon nanotube web laminate.

[0007] According to the present invention, it is possible to provide a prepreg with excellent strength for the resulting fiber-reinforced composite material. Therefore, the prepreg of the present invention is useful as a molding material in various fields where strength is required.

[0008] This is a top view illustrating an example of the process for manufacturing carbon nanotube webs. This is a cross-sectional view illustrating an example of the process for manufacturing carbon nanotube webs.

[0009] [Prepreg] The prepreg of the present invention is a prepreg containing a resin composition and a carbon nanotube film, wherein the resin composition is impregnated into the carbon nanotube film, the resin composition contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate. The prepreg of the present invention can be used as a molding material in various fields requiring strength because it can provide a fiber-reinforced composite material with excellent strength.

[0010] The reason why the prepreg of the present invention can exhibit the above-mentioned excellent effects is not entirely clear, but it is thought to be as follows. The resin composition contained in the prepreg of the present invention has a specific aromatic kernel concentration, and therefore has a high affinity with the carbon nanotube web surface constituting the carbon nanotube film, thereby allowing the resin composition to sufficiently impregnate between the fibers. Furthermore, the carbon nanotube film contained in the prepreg of the present invention is a web laminate with a specific basis weight. Therefore, it is thought that the carbon nanotube web is uniformly embedded throughout the molded body in a form that takes advantage of its anisotropy in the fiber-reinforced composite material obtained by molding and curing the prepreg of the present invention. For these reasons, it is thought that the prepreg of the present invention can produce a fiber-reinforced composite material with excellent strength. In the context of the prepreg of the present invention, "the resin composition is impregnated into the carbon nanotube film" means that the resin composition is substantially present between the fibers constituting the carbon nanotube film without any gaps. Furthermore, in the prepreg of the present invention, "the resin composition is impregnated into the carbon nanotube film and the carbon fiber sheet" means that the resin composition is substantially present between the fibers constituting the carbon nanotube film and the carbon fiber sheet without any gaps.

[0011] <Resin Composition> The resin composition constituting the prepreg of the present invention contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, and the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more. The aromatic kernel concentration of the resin composition is the aromatic kernel concentration relative to all components contained in the resin composition. Therefore, the aromatic kernel concentration of the resin composition is the aromatic kernel concentration relative to the total mass of the radical polymerization-type thermosetting oligomer, polymerization initiator, polymerizable monomer and other components.

[0012] The aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, preferably 0.2 mol / kg or more, more preferably 0.5 mol / kg or more, even more preferably 0.8 mol / kg or more, even more preferably 1.0 mol / kg or more, even more preferably 1.2 mol / kg or more, even more preferably 1.5 mol / kg or more, and even more preferably 1.7 mol / kg or more. There is no particular upper limit to the aromatic kernel concentration of the resin composition, but it is preferably 7.0 mol / kg or less, more preferably 6.0 mol / kg or less, and even more preferably 5.0 mol / kg or less.

[0013] Therefore, the aromatic kernel concentration of the resin composition is preferably 0.1 to 7.0 mol / kg, more preferably 0.1 to 6.0 mol / kg, even more preferably 0.1 to 5.0 mol / kg, even more preferably 0.2 to 5.0 mol / kg, even more preferably 0.5 to 5.0 mol / kg, even more preferably 0.8 to 5.0 mol / kg, even more preferably 1.0 to 5.0 mol / kg, even more preferably 1.2 to 5.0 mol / kg, even more preferably 1.5 to 5.0 mol / kg, and even more preferably 1.7 to 5.0 mol / kg. By having the aromatic kernel concentration of the resin composition within the above range, the impregnation and adhesion to the carbon nanotube film are excellent, and the resulting fiber-reinforced composite material has excellent strength. In this invention, the aromatic kernel concentration of the resin composition is the number of moles of aromatic rings (such as benzene rings) contained in 1 kg of the resin composition. Note that the number of moles of aromatic rings in a polycyclic compound is calculated by multiplying the number of rings by the number of moles of the compound. For example, the naphthalene skeleton has two rings, the anthracene skeleton has three rings, and the biphenyl skeleton has two rings.

[0014] From the viewpoint of improving strength by using carbon nanotube film as the main reinforcing fiber, the aromatic kernel concentration of the resin composition is preferably 0.1 mol / kg or more, preferably 0.2 mol / kg or more, more preferably 0.5 mol / kg or more, even more preferably 0.8 mol / kg or more, even more preferably 1.0 mol / kg or more, even more preferably 1.2 mol / kg or more, even more preferably 1.5 mol / kg or more, and even more preferably 1.7 mol / kg or more. Furthermore, the aromatic kernel concentration of the resin composition is preferably 7.0 mol / kg or less, more preferably 6.0 mol / kg or less, even more preferably 5.0 mol / kg or less, even more preferably 4.0 mol / kg or less, even more preferably 3.0 mol / kg or less, even more preferably 2.5 mol / kg or less, and even more preferably 2.0 mol / kg or less.

[0015] Therefore, the aromatic kernel concentration of the resin composition is preferably 0.1 to 7.0 mol / kg, more preferably 0.1 to 6.0 mol / kg, even more preferably 0.1 to 5.0 mol / kg, even more preferably 0.2 to 5.0 mol / kg, even more preferably 0.5 to 4.0 mol / kg, even more preferably 0.8 to 4.0 mol / kg, even more preferably 1.0 to 3.0 mol / kg, even more preferably 1.2 to 3.0 mol / kg, even more preferably 1.5 to 2.5 mol / kg, and even more preferably 1.7 to 2.0 mol / kg.

[0016] From the viewpoint of improving strength by using carbon nanotube film and carbon fiber sheet as the main reinforcing fibers, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, preferably 0.5 mol / kg or more, more preferably 1.0 mol / kg or more, even more preferably 2.0 mol / kg or more, even more preferably 2.5 mol / kg or more, even more preferably 3.0 mol / kg or more, even more preferably 3.5 mol / kg or more, and even more preferably 4.0 mol / kg or more. Furthermore, there is no particular upper limit to the aromatic kernel concentration of the resin composition, but it is preferably 7.0 mol / kg or less, more preferably 6.0 mol / kg or less, and even more preferably 5.0 mol / kg or less.

[0017] Therefore, the aromatic kernel concentration of the resin composition is preferably 0.1 to 7.0 mol / kg, more preferably 0.5 to 7.0 mol / kg, even more preferably 1.0 to 6.0 mol / kg, even more preferably 2.0 to 6.0 mol / kg, even more preferably 2.5 to 6.0 mol / kg, even more preferably 3.0 to 5.0 mol / kg, even more preferably 3.5 to 5.5 mol / kg, and even more preferably 4.0 to 5.0 mol / kg.

[0018] The content of the resin composition in the prepreg is preferably 15 to 65% by mass, more preferably 20 to 65% by mass, even more preferably 20 to 60% by mass, even more preferably 20 to 55% by mass, even more preferably 25 to 50% by mass, even more preferably 30 to 50% by mass, even more preferably 30 to 45% by mass, and even more preferably 35 to 45% by mass, based on the total amount of the prepreg. By having the resin composition content within the above range, the resulting fiber-reinforced composite material will have excellent strength.

[0019] When the prepreg contains a carbon fiber sheet, the content of the resin composition in the prepreg containing the carbon fiber sheet, as described later, is preferably 15 to 60% by mass, more preferably 20 to 55% by mass, even more preferably 25 to 50% by mass, even more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass, based on the total amount of the prepreg. By having the resin composition content within the above range, the resulting fiber-reinforced composite material will have excellent strength.

[0020] The viscosity of the resin composition at 80°C is preferably 0.1 to 30 Pa·s, more preferably 0.1 to 10 Pa·s, even more preferably 0.1 to 8.0 Pa·s, even more preferably 0.1 to 7.0 Pa·s, even more preferably 0.1 to 4.0 Pa·s, and even more preferably 0.2 to 1.0 Pa·s. The viscosity of the resin composition within this range provides excellent impregnation and adhesion to the carbon nanotube film, and the resulting fiber-reinforced composite material can have improved strength. The resin composition can also be manufactured after impregnating its raw material components into a carbon nanotube film. Therefore, the viscosity of the resin composition at 80°C can be determined by measuring the viscosity of a resin composition obtained by aging the raw material components of the resin composition at 50°C for 72 hours. Specifically, it can be determined by the method described in the examples.

[0021] (Radical Polymerization Thermosetting Oligomer) The radical polymerization thermosetting oligomer contained in the resin composition preferably contains at least one selected from the group consisting of urethane (meth)acrylate, epoxy (meth)acrylate, and unsaturated polyester, more preferably contains at least one selected from the group consisting of urethane (meth)acrylate and epoxy (meth)acrylate, and even more preferably contains urethane (meth)acrylate. Furthermore, the radical polymerization thermosetting oligomer contained in the resin composition is more preferably at least one selected from the group consisting of urethane (meth)acrylate, epoxy (meth)acrylate, and unsaturated polyester, even more preferably at least one selected from the group consisting of urethane (meth)acrylate and epoxy (meth)acrylate, and even more preferably urethane (meth)acrylate. In the present invention, "(meth)acrylate" means at least one selected from the group consisting of "acrylate" and "methacrylate," "(meth)acryloyl group" means at least one selected from the group consisting of "acryloyl group" and "methacryloyl group," and "(meth)acrylic acid" means at least one selected from the group consisting of "acrylic acid" and "methacrylic acid."

[0022] The radical polymerization-based thermosetting oligomer may consist of at least one selected from the group consisting of urethane (meth)acrylate, epoxy (meth)acrylate, and unsaturated polyester, but may also contain other radical polymerization-based thermosetting oligomers as long as the effects of the present invention are not impaired.

[0023] The aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, but preferably the radical polymerization-based thermosetting oligomer contained in the resin composition has aromatic kernels. That is, it is preferable that the structural units (structural units derived from monomers) constituting the radical polymerization-based thermosetting oligomer have aromatic kernels, and it is preferable that the monomer used as a raw material is an aromatic monomer. More specifically, it is preferable to use an aromatic isocyanate compound as a raw material for urethane (meth)acrylate, and it is preferable to use an aromatic dicarboxylic acid as a raw material for unsaturated polyester. The aromatic kernel concentration of the radical polymerization-based thermosetting oligomer is preferably 0.0 to 7.0 mol / kg, more preferably 0.1 to 6.0 mol / kg, even more preferably 0.2 to 5.0 mol / kg, even more preferably 0.5 to 5.0 mol / kg, even more preferably 1.0 to 5.0 mol / kg, even more preferably 1.2 to 5.0 mol / kg, even more preferably 1.5 to 5.0 mol / kg, even more preferably 2.0 to 5.0 mol / kg, and even more preferably 2.0 to 4.0 mol / kg. By having the aromatic kernel concentration of the radical polymerization-based thermosetting oligomer within the above range, the impregnation and adhesion to the carbon nanotube film are excellent, and the resulting fiber-reinforced composite material has excellent strength.

[0024] Furthermore, the concentration of aromatic kernels derived from the radical polymerization-based thermosetting oligomer in the total aromatic kernel concentration of the resin composition is preferably 0.0 to 7.0 mol / kg, more preferably 0.2 to 6.0 mol / kg, even more preferably 0.5 to 5.0 mol / kg, even more preferably 0.8 to 5.0 mol / kg, even more preferably 1.0 to 4.0 mol / kg, even more preferably 1.5 to 4.0 mol / kg, even more preferably 2.0 to 3.5 mol / kg, even more preferably 2.0 to 3.0 mol / kg, even more preferably 2.3 to 2.8 mol / kg, and even more preferably 2.5 to 2.7 mol / kg. By having the concentration of aromatic kernels derived from the radical polymerization-based thermosetting oligomer in the total aromatic kernel concentration of the resin composition within the above range, the impregnation and adhesion to the carbon nanotube film are excellent, and the resulting fiber-reinforced composite material has excellent strength.

[0025] The total content of urethane (meth)acrylate, epoxy (meth)acrylate, and unsaturated polyester is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and even more preferably 99 to 100% by mass, based on the total amount of radical polymerization-based thermosetting oligomer.

[0026] The content of the radical polymerization-based thermosetting oligomer in the resin composition is preferably 35 to 98% by mass, more preferably 50 to 85% by mass, more preferably 55 to 80% by mass, even more preferably 60 to 80% by mass, and even more preferably 65 to 75% by mass.

[0027] [Urethane (meth)acrylate] Urethane (meth)acrylate is a radically polymerizable compound having a urethane bond and a (meth)acryloyl group in the molecule, without particular limitation. The urethane (meth)acrylate is preferably an adduct of a (meth)acrylate having a hydroxyl group of a polyisocyanate. The "adduct of a (meth)acrylate having a hydroxyl group of a polyisocyanate" is an adduct obtained by forming a urethane bond from the isocyanate group of the polyisocyanate and the hydroxyl group (hydroxyl group) of the (meth)acrylate having a hydroxyl group. The details of the urethane (meth)acrylate will be described below. By using the following urethane (meth)acrylates, the impregnation property and adhesion to the carbon nanotube film are excellent, and the resulting fiber-reinforced composite material has excellent strength.

[0028] The urethane (meth)acrylate preferably has a structural unit derived from a compound having two or more isocyanate groups and a structural unit derived from hydroxyalkyl (meth)acrylate, more preferably a structural unit derived from a compound having two or more isocyanate groups, a structural unit derived from hydroxyalkyl (meth)acrylate, and a structural unit derived from a polyol or a polyester polyol, and still more preferably a structural unit derived from a compound having two or more isocyanate groups, a structural unit derived from hydroxyalkyl (meth)acrylate, and a structural unit derived from a polyol.

[0029] Examples of the compound having two or more isocyanate groups include aromatic isocyanate compounds, alicyclic isocyanate compounds, aliphatic isocyanate compounds, etc. Among these, from the viewpoint of improving the strength of the obtained fiber reinforced composite material, the compound having two or more isocyanate groups is preferably at least one selected from the group consisting of aromatic isocyanate compounds and alicyclic isocyanate compounds. From the viewpoint of improving the aromatic nucleus concentration of the resin composition and the impregnation property into the carbon nanotube film, the compound having two or more isocyanate groups is more preferably an aromatic isocyanate compound. Also, from the viewpoints of physical property balance and impact resistance, the compound having two or more isocyanate groups is more preferably an alicyclic isocyanate compound.

[0030] Further, the isocyanate compound is also preferably used in the form of a trifunctional isocyanate (nurate type polyisocyanate) (compound having three isocyanate groups) having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound (compound having two isocyanate groups), or an isocyanate prepolymer modified with a polyol.

[0031] The aromatic isocyanate compound is preferably at least one selected from the group consisting of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,3-xylylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, diphenylmethane diisocyanate (4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate or a mixture of the isomers), polymethylene polyphenyl polyisocyanate and m-tetramethylxylene diisocyanate, and more preferably at least one selected from the group consisting of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate.

[0032] The alicyclic isocyanate compound is preferably at least one selected from the group consisting of isophorone diisocyanate, hydrogenated xylylene diisocyanate (1,3-bis(isocyanatomethyl)cyclohexane), norbornene diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated methylenebisphenyl diisocyanate, and 1,4-cyclohexane diisocyanate and their nurate-type polyisocyanates, more preferably at least one selected from the group consisting of isophorone diisocyanate and its nurate-type polyisocyanates, and even more preferably isophorone diisocyanate. The nurate-type polyisocyanate of isophorone diisocyanate is preferably at least one selected from trimers, pentamers, heptamers, nocumer, and decamer of IPDI, in which the isophorone diisocyanate (IPDI) monomer forms a nurate ring, or a mixture thereof.

[0033] Examples of aliphatic isocyanate compounds include 1,6-hexamethylene diisocyanate and trimethylene diisocyanate. These isocyanate compounds can be used individually or in combination of two or more.

[0034] The hydroxyalkyl (meth)acrylate is preferably at least one selected from the group consisting of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, trimethylolpropanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate, more preferably at least one selected from the group consisting of hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, and even more preferably hydroxyethyl (meth)acrylate.

[0035] The polyol is preferably at least one selected from the group consisting of aliphatic diols and etherified diphenols, and more preferably an aliphatic diol. The aliphatic diol is preferably at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, propylene glycol, and diethylene glycol, and more preferably 1,3-propanediol. Examples of polyester polyols include those obtained by polycondensation of at least one selected from the group consisting of unsaturated acids and saturated acids and at least one selected from the group consisting of aliphatic diols and etherified diphenols.

[0036] The molar ratio of structural units derived from a compound having two or more isocyanate groups to structural units derived from a hydroxyalkyl (meth)acrylate [compound having two or more isocyanate groups / hydroxyalkyl (meth)acrylate] is preferably 0.5 to 5.0, more preferably 0.8 to 3.0, and even more preferably 1.0 to 2.0. The molar ratio of a compound having two or more isocyanate groups to structural units derived from a polyol or polyester polyol [compound having two or more isocyanate groups / polyol or polyester polyol] is preferably 0.4 to 4.0, more preferably 1.0 to 3.0, and even more preferably 1.6 to 2.1.

[0037] When the radical polymerization-based thermosetting oligomer is urethane (meth)acrylate, the acrylic equivalent of the radical polymerization-based thermosetting oligomer is preferably 200 to 1600 g / eq, more preferably 250 to 1000 g / eq, even more preferably 300 to 800 g / eq, even more preferably 300 to 600 g / eq, and even more preferably 400 to 500 g / eq. By having the acrylic equivalent of the radical polymerization-based thermosetting oligomer within the above range, the strength and mechanical properties of the fiber-reinforced composite material obtained from the prepreg can be improved.

[0038] The urethane (meth)acrylate is preferably synthesized by an addition reaction that forms a urethane bond between a polyisocyanate (isocyanate compound) and a (meth)acrylate having a hydroxyl group, but a polymerization catalyst or polymerization inhibitor may be present during this process. Preferred polymerization catalysts are those shown in the section on [Polymerization Catalysts] below, and preferred polymerization inhibitors are those shown in the section on [Polymerization Inhibitors] below.

[0039] [Epoxy (meth)acrylate] Epoxy (meth)acrylate is a polymer obtained by an addition reaction between an epoxy resin and an unsaturated basic acid, although there are no particular limitations. The epoxy resin is not particularly limited, and can be epi-bis-type glycidyl ether, novolac-type glycidyl ether, brominated glycidyl ether, other glycidyl ethers, nitrogen-containing types, glycidyl esters, peracetic acid oxidized types, glycol-type glycidyl ethers, etc., and may be used alone or in combination of two or more. The unsaturated basic acid is not particularly limited, and is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, sorbic acid, hydroxymethyl methacrylate malate, hydroxyethyl acrylate malate, hydroxypropyl methacrylate malate, hydroxypropyl acrylate malate, and dicyclopentadiene acrylate malate, and may be used alone or in combination of two or more.

[0040] The method for producing epoxy (meth)acrylate is not particularly limited and may be carried out by conventionally known methods. Specifically, epoxy (meth)acrylate can be produced by methods such as those described in "Vinyl Ester Resins" (edited by the Vinyl Ester Resin Research Association, Chemical Daily Co., Ltd., 1993). Polymerization catalysts and polymerization inhibitors may be present during production. Preferred polymerization catalysts are those shown in the [Polymerization Catalysts] section below, and preferred polymerization inhibitors are those shown in the [Polymerization Inhibitors] section below. The reaction temperature is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C.

[0041] [Unsaturated Polyester] Unsaturated polyester is not particularly limited as long as it is a polyester having unsaturated bonds, but it is preferable that it contains structural units derived from saturated dicarboxylic acids, structural units derived from unsaturated dicarboxylic acids and structural units derived from diols, and it is more preferable that it consists substantially of structural units derived from saturated dicarboxylic acids, structural units derived from unsaturated dicarboxylic acids and structural units derived from diols.

[0042] The saturated dicarboxylic acid that provides the constituent units derived from saturated dicarboxylic acids is preferably at least one selected from the group consisting of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids, with aromatic dicarboxylic acids being more preferred. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. From the viewpoint of balancing the ease of obtaining raw materials with the performance of the resulting unsaturated polyester, it is preferably at least one selected from the group consisting of terephthalic acid, isophthalic acid, and phthalic acid. The aromatic dicarboxylic acid may also be an anhydride. By using the aromatic dicarboxylic acid, an unsaturated polyester with excellent mechanical properties, water resistance, and chemical resistance can be obtained. Examples of alicyclic dicarboxylic acids include 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and endomethylenetetrahydrophthalic anhydride. Examples of aliphatic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, succinic acid substituted with alkyl groups having 16 to 18 carbon atoms, and dimer acids. Saturated dicarboxylic acids may be used alone or in combination of two or more types.

[0043] Examples of unsaturated dicarboxylic acids that provide structural units derived from unsaturated dicarboxylic acids include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride. Preferably, it is at least one selected from the group consisting of maleic acid, maleic anhydride, and fumaric acid, more preferably at least one selected from the group consisting of maleic acid and maleic anhydride, and even more preferably maleic anhydride. The unsaturated dicarboxylic acid may be used alone or in combination of two or more types.

[0044] Examples of diols that provide constituent units derived from diols include aliphatic diols, alicyclic diols, etherified diphenols, and polyalkylene glycols, with aliphatic diols being preferred. Examples of aliphatic diols include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methylpropane-1,3-diol, and 2-butyl -2-ethylpropane-1,3-diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl-3-Hydro Examples include roxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, and dipropylene glycol. Preferably, it is at least one selected from the group consisting of ethylene glycol, 1,2-propanediol (propylene glycol), dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, and 1,8-octanediol. More preferably, it is at least one selected from the group consisting of neopentyl glycol, propylene glycol, and dipropylene glycol. Even more preferably, it is at least two selected from the group consisting of neopentyl glycol, propylene glycol, and dipropylene glycol. Even more preferably, it is neopentyl glycol, propylene glycol, and dipropylene glycol. Aliphatic diols may be used alone or in combination of two or more, and it is preferable to use two or more in combination.

[0045] Examples of alicyclic diols include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F. Examples of etherified diphenols include bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct. Examples of polyalkylene glycols include polyethylene glycol, polyalkylene glycol, and polytetramethylene glycol. Diols may be used alone or in combination of two or more.

[0046] The unsaturated polyester resin may contain other structural units besides those described above. Examples of components that provide other structural units include monocarboxylic acids, polycarboxylic acids with a valency of 3 or higher, monoalcohols, polyhydric alcohols with a valency of 3 or higher, and hydroxycarboxylic acids. In addition, lower alkyl esters and anhydrides of the carboxylic acid components (saturated dicarboxylic acids, unsaturated dicarboxylic acids, monocarboxylic acids, polycarboxylic acids with a valency of 3 or higher, and hydroxycarboxylic acids) may be used.

[0047] The molar ratio [carboxyl groups / hydroxyl groups] of the total carboxyl groups of the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, trivalent or higher polycarboxylic acid, hydroxycarboxylic acid) to the total hydroxyl groups of the alcohol component (dihydric alcohol, monoalcohol, trivalent or higher polyhydric alcohol, hydroxycarboxylic acid) is preferably 0.9 / 1.1 to 1.1 / 0.9, and more preferably 0.95 / 1.05 to 1.05 / 0.95. The ratio (moles) of constituent units derived from unsaturated dicarboxylic acid in constituent units derived from the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, trivalent or higher polycarboxylic acid, hydroxycarboxylic acid) is preferably 70 to 99 mol%, more preferably 80 to 99 mol%, even more preferably 90 to 99 mol%, and even more preferably 90 to 98 mol%, in terms of the number of carboxyl groups. The ratio (moles) of constituent units derived from diols in the constituent units derived from the aforementioned alcohol component (diol, monoalcohol, polyhydric alcohol of trihydric or higher, hydroxycarboxylic acid) is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol%, in terms of the number of hydroxyl groups, and the constituent units derived from the aforementioned alcohol component may consist only of constituent units derived from diols.

[0048] The method for producing the unsaturated polyester resin is not particularly limited, but it can be obtained by reacting a carboxylic acid component with an alcohol component. A polymerization catalyst or polymerization inhibitor may be present during the reaction. Preferred polymerization catalysts are those shown in the section on [Polymerization Catalysts] below, and preferred polymerization inhibitors are those shown in the section on [Polymerization Inhibitors] below. The reaction temperature is preferably 150 to 280°C, and more preferably 160 to 250°C. The endpoint of the reaction can be determined by the acid value of the reaction mixture, the amount of condensation water (or alcohol in the case of lower alkyl esters as raw materials), the viscosity of the resulting polyester, etc.

[0049] (Polymerization Initiator) The resin composition contains a polymerization initiator. The polymerization initiator is used to quickly obtain a homogeneous cured product during molding. The type and amount of the initiator may be used depending on the application. The polymerization initiator is preferably an organic peroxide.

[0050] The organic peroxide is preferably at least one selected from the group consisting of ketone peroxide compounds, diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, dialkyl peroxide compounds, and peroxyketal compounds, more preferably at least one selected from the group consisting of peroxyester compounds and dialkyl peroxide compounds, and even more preferably a peroxyester compound.

[0051] Examples of ketone peroxide compounds include methyl ethyl ketone peroxide and acetylacetone peroxide. Examples of diacyl peroxide compounds include dibenzoyl peroxide. Examples of peroxyester compounds include t-butyl peroxybenzoate, t-butyl peroxyoctoate, and t-butyl peroxy-2-ethylhexyl monocarbonate. Examples of dialkyl peroxide compounds include dicumyl peroxide and t-butylcumyl peroxide. Examples of peroxyketal compounds include 1,1-di(t-hexyl peroxy)cyclohexane, 1,1-di(t-butyl peroxy)cyclohexane, and 1,1-di(t-butyl peroxy)-3,3,5-trimethylcyclohexane. Organic peroxides may be used alone or in combination of two or more. Among these, from the viewpoint of freedom in molding conditions and storage stability, it is preferably at least one selected from the group consisting of t-butylperoxy-2-ethylhexyl monocarbonate and t-butylcumyl peroxide, and more preferably t-butylperoxy-2-ethylhexyl monocarbonate.

[0052] The 10-hour half-life temperature of the polymerization initiator is preferably 45 to 130°C, more preferably 70 to 120°C, and even more preferably 90 to 110°C. When the 10-hour half-life temperature of the polymerization initiator is within the above range, the resin composition can be stored for a long period of time and exhibits excellent curing speed. The polymerization initiator may be used alone or in combination of two or more types.

[0053] The polymerization initiator content is preferably 0.3 to 4.0% by mass, more preferably 0.5 to 3.0% by mass, even more preferably 0.8 to 2.5% by mass, and even more preferably 1.0 to 2.0% by mass in the resin composition. By setting the polymerization initiator content within the above range, the resin composition can be stored for a long period of time and exhibits excellent curing speed.

[0054] (Polymerizable monomer) The resin composition preferably further contains polymerizable monomers. Before curing, the polymerizable monomers act as diluents to give the resin composition fluidity and also function as solvents for the resin. After curing, they act as crosslinked portions, improving the strength and hardness of the resulting molded product.

[0055] If the resin composition contains a polymerizable monomer, it is preferable that the polymerizable monomer contained in the resin composition has an aromatic kernel in order to increase the aromatic kernel concentration of the resin composition. If the polymerizable monomer has an aromatic kernel, the radical polymerization-based thermosetting oligomer does not need to contain an aromatic kernel, but it is preferable that the radical polymerization-based thermosetting oligomer also has an aromatic kernel. That is, it is preferable that the polymerizable monomer has an aromatic kernel, and it is also preferable that the radical polymerization-based thermosetting oligomer also has an aromatic kernel, and it is more preferable that both the polymerizable monomer and the radical polymerization-based thermosetting oligomer have an aromatic kernel. The aromatic kernel concentration of the polymerizable monomer is preferably 0.0 to 10.0 mol / kg, more preferably 1.0 to 10.0 mol / kg, even more preferably 3.0 to 10.0 mol / kg, even more preferably 4.0 to 10.0 mol / kg, even more preferably 5.0 to 10.0 mol / kg, even more preferably 6.0 to 9.0 mol / kg, even more preferably 6.0 to 8.0 mol / kg, and even more preferably 6.0 to 7.0 mol / kg. Having the aromatic kernel concentration of the polymerizable monomer within the above range results in excellent impregnation and adhesion to the carbon nanotube film, and the resulting fiber-reinforced composite material exhibits superior strength.

[0056] Furthermore, the concentration of aromatic kernels derived from the polymerizable monomer in the total aromatic kernel concentration of the resin composition is preferably 0.0 to 7.0 mol / kg, more preferably 0.1 to 6.0 mol / kg, even more preferably 0.1 to 5.0 mol / kg, even more preferably 0.2 to 5.0 mol / kg, even more preferably 0.5 to 4.0 mol / kg, even more preferably 0.8 to 4.0 mol / kg, even more preferably 1.0 to 3.0 mol / kg, even more preferably 1.2 to 3.0 mol / kg, even more preferably 1.5 to 2.5 mol / kg, and even more preferably 1.7 to 2.0 mol / kg. By having the concentration of aromatic kernels derived from the polymerizable monomer in the total aromatic kernel concentration of the resin composition within the above range, the impregnation and adhesion to the carbon nanotube film are excellent, and the resulting fiber-reinforced composite material has excellent strength.

[0057] The polymerizable monomer is preferably at least one selected from the group consisting of styrene monomers, (meth)acrylic acid monomers, and vinyl acetate monomers, more preferably at least one selected from the group consisting of styrene monomers and (meth)acrylic acid monomers, and even more preferably styrene monomers. The styrene monomer is preferably at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene, and more preferably styrene.

[0058] Examples of (meth)acrylic acid monomers include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, ethoxylated-o-phenylphenol acrylate, methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and glycidyl (meth)acrylate. Hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-(meth)acroyloxyethyl succinate, 2-(meth)acroyloxyethyl maleate, Examples include 2-(meth)acroyloxyethyl tarate, 2-(meth)acrylateoyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. At least one selected from the group consisting of phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, ethoxylated-o-phenylphenol acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate is preferred.

[0059] Furthermore, from the viewpoint of increasing the aromatic kernel concentration of the resin composition contained in the prepreg of the present invention and improving the strength of the resulting fiber-reinforced composite material, the polymerizable monomer is more preferably at least one selected from the group consisting of styrene monomers and (meth)acrylic acid monomers having aromatic rings, and even more preferably a styrene monomer.

[0060] Among these, the polymerizable monomer more preferably contains at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and ethoxylated-o-phenylphenol acrylate; even more preferably contains at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; even more preferably contains at least one selected from the group consisting of styrene and benzyl (meth)acrylate; and even more preferably contains styrene. Furthermore, the polymerizable monomer is even more preferably at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and ethoxylated-o-phenylphenol acrylate.

[0061] Furthermore, from the viewpoint of improving the strength of the resulting fiber-reinforced composite material, the polymerizable monomer more preferably contains both a monofunctional polymerizable monomer and a bifunctional or more-functional polymerizable monomer, and even more preferably contains both a monofunctional polymerizable monomer and a bifunctional polymerizable monomer. The monofunctional polymerizable monomer used in the combination of a monofunctional polymerizable monomer and a bifunctional or more-functional polymerizable monomer is preferably at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and ethoxylated-o-phenylphenol acrylate, more preferably at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate, even more preferably at least one selected from the group consisting of styrene and benzyl (meth)acrylate, and even more preferably styrene. The two- or more functional polymerizable monomer used in the combination of a monofunctional polymerizable monomer and a two- or more functional polymerizable monomer is preferably at least one selected from the group consisting of ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate; more preferably at least one selected from the group consisting of ethylene glycol di(meth)acrylate and diethylene glycol di(meth)acrylate; and even more preferably diethylene glycol di(meth)acrylate.

[0062] The polymerizable monomer content in the resin composition is preferably 1 to 60% by mass, more preferably 10 to 40% by mass, even more preferably 10 to 35% by mass, even more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass, based on the total amount of the resin composition. Furthermore, the polymerizable monomer content is preferably 2 to 90 parts by mass, more preferably 15 to 60 parts by mass, more preferably 20 to 50 parts by mass, even more preferably 20 to 40 parts by mass, and even more preferably 25 to 30 parts by mass, based on 100 parts by mass of the radical polymerization-based thermosetting oligomer. By having the polymerizable monomer content within the above range, the fluidity of the resin composition before curing can be maintained and the strength of the resulting fiber-reinforced composite material can be increased.

[0063] (Other Components) The resin composition may contain other components besides the radical polymerization-based thermosetting oligomer and polymerization initiator, to the extent that they do not impair the effects of the present invention. Examples of components other than the radical polymerization-based thermosetting oligomer and polymerization initiator include polymerization inhibitors, polymerization catalysts, pigments, low shrinkage agents, internal release agents, and dispersants. Depending on the application, these may be added during the synthesis of the radical polymerization-based thermosetting oligomer, mixed when compounding the components of the resin composition, or mixed immediately before use. In particular, the resin composition preferably contains a polymerization inhibitor to improve storage stability and workability.

[0064] [Polymerization Inhibitor] The resin composition preferably contains a polymerization inhibitor. The polymerization inhibitor is added to prevent gelation during manufacturing, ensure pot life during molding, and improve storage stability. Preferably, the polymerization inhibitor is at least one selected from the group consisting of polyhydric phenolic polymerization inhibitors and quinone-based polymerization inhibitors, and more preferably a polyhydric phenolic polymerization inhibitor. Examples of quinone-based polymerization inhibitors include parabenzoquinone and tolquinone. Preferably, the polyhydric phenolic polymerization inhibitor is at least one selected from the group consisting of tolhydroquinone, dibutylhydroxytoluene, hydroquinone, trimethylhydroquinone, and tert-butylcatechol, more preferably at least one selected from the group consisting of tolhydroquinone and dibutylhydroxytoluene, and even more preferably dibutylhydroxytoluene. It is even more preferable that the polyhydric phenolic polymerization inhibitor contains both tolhydroquinone and dibutylhydroxytoluene.

[0065] The polymerization inhibitor content is preferably 0.001 to 0.1% by mass, more preferably 0.005 to 0.08% by mass, and even more preferably 0.01 to 0.05% by mass, based on the total amount of the resin composition. By having the polymerization inhibitor content within the above range, it is possible to maintain the curability of the resin composition while ensuring a sufficient pot life and improving storage stability.

[0066] [Polymerization Catalyst] The resin composition may contain a polymerization catalyst. The polymerization catalyst is preferably a tin compound such as dibutyltin dilaurate or dibutyltin diacetate. Tin compounds are particularly preferred when the radical polymerization-type thermosetting oligomer is a urethane (meth)acrylate. The content of the polymerization catalyst in the resin composition is preferably 0.002 to 0.1% by mass, more preferably 0.005 to 0.07% by mass, and even more preferably 0.01 to 0.05% by mass. By having a polymerization catalyst content within the above range, the reaction between the fibers and the resin is promoted, and the mechanical properties can be improved.

[0067] Furthermore, when the radical polymerization-based thermosetting oligomer is an epoxy (meth)acrylate, a polymerization catalyst that promotes the esterification reaction may be used. When the radical polymerization-based thermosetting oligomer is an epoxy (meth)acrylate, the polymerization catalyst that promotes the esterification reaction is preferably at least one selected from the group consisting of compounds containing tertiary nitrogen, phosphorus compounds, amine salts, and antimony compounds, with compounds containing tertiary nitrogen being more preferred. Examples of compounds containing tertiary nitrogen include triethylamine, pyridine derivatives, and imidazole derivatives, with imidazole derivatives being preferred. Examples of phosphorus compounds include trimethylphosphine and triphenylphosphine. Examples of amine salts include tetramethylammonium chloride and benzyltriethylamine chloride. Examples of antimony compounds include triphenylantimony and trimethylantimony. The amount of polymerization catalyst used to promote the esterification reaction is preferably 0.005 to 0.7% by mass, more preferably 0.01 to 0.6% by mass, even more preferably 0.05 to 0.5% by mass, and even more preferably 0.08 to 0.5% by mass, relative to the total amount of epoxy resin and unsaturated basic acid.

[0068] Furthermore, even when the radical polymerization-based thermosetting oligomer is an unsaturated polyester, a polymerization catalyst that promotes the esterification reaction may be used. Examples of polymerization catalysts that promote the esterification reaction when the radical polymerization-based thermosetting oligomer is an unsaturated polyester include at least one metal compound selected from antimony, germanium, titanium, tin, zinc, aluminum, and manganese. The amount of polymerization catalyst that promotes the esterification reaction added is preferably 0.01 to 1.5 mol% relative to the saturated carboxylic acid component.

[0069] <Carbon Nanotube Film> The prepreg of the present invention contains a carbon nanotube film, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2The carbon nanotube film is a carbon nanotube web laminate. Hereinafter, "carbon nanotube" will also be written as "CNT".

[0070] The carbon nanotube film is preferably composed of substantially only carbon, and more preferably contains 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 99% by mass or more, of 100% by mass of the CNT film.

[0071] The carbon nanotube film contained in the prepreg of the present invention is a carbon nanotube web laminate (CNT web laminate), and preferred carbon nanotube web laminates are shown below. Note that the carbon nanotube web laminate is a laminate of carbon nanotube webs (CNT webs).

[0072] A CNT web laminate can be manufactured, for example, by producing multiple sheets of CNT webs obtained by extracting multiple CNTs from a CNT forest, and then laminating each CNT web, or by manufacturing a roll by wrapping multiple CNT webs obtained by extracting multiple CNTs from a CNT forest around the circumferential surface of a roller multiple times, and then cutting open the roll along the rotation axis of the roller.

[0073] When manufacturing a CNT film by laminating multiple CNT webs in sheet form, the CNT webs may be laminated so that the longitudinal direction of the CNT fibers constituting one CNT web is parallel to the longitudinal direction of the CNT fibers constituting another CNT web, or they may be laminated so that they intersect (for example, orthogonally). From the viewpoint of interlayer strength of the CNT webs, it is preferable to laminate the CNT webs so that the longitudinal direction of the CNT fibers constituting one CNT web is parallel to the longitudinal direction of the CNT fibers constituting another CNT web.

[0074] Examples of CNT film shapes include rectangular, square, trapezoidal, parallelogram, rhombus, kite, elliptical, and circular shapes.

[0075] The basis weight of the carbon nanotube film contained in the prepreg of the present invention is 0.0226 to 170 mg / cm 2 and, from the viewpoints of productivity and physical strength of the final product, is preferably 0.0339 to 85 mg / cm 2 and more preferably 0.0565 to 17 mg / cm 2 is. Note that the basis weight of the CNT film is usually larger than that of the CNT web-like body, preferably 2 times or more larger. The basis weight of the CNT film can be determined by measuring the mass of the CNT film with a balance and dividing the mass by the area of the CNT film. The CNT film contained in the prepreg of the present invention is a CNT web laminate, but the number of layers of the CNT web in the CNT film may be set according to the purpose of the obtained prepreg and is not particularly limited. For example, from the viewpoints of productivity and adhesiveness, etc., it is preferably 10 to 10,000, more preferably 20 to 5,000, still more preferably 30 to 1,000, and particularly preferably 40 to 500. The web of carbon nanotubes means a web containing a plurality of CNT fibers. That is, the carbon nanotube web preferably consists of a plurality of carbon nanotube fibers, and the plurality of carbon nanotube fibers are arranged in the same direction.

[0076] The CNT forest refers to an aggregate of a plurality of CNTs provided on a substrate and oriented in a direction perpendicular to the surface of the substrate. In the CNT forest, a plurality of CNTs stand on the substrate.

[0077] The CNT forest can be obtained, for example, by performing a chemical vapor deposition method (CVD method) using a catalyst substrate including a substrate and a catalyst layer provided on the substrate. The CVD method is a method in which after arranging the catalyst substrate in a reaction chamber, a raw material gas is supplied into the reaction chamber to grow CNTs on the surface of the catalyst layer. As the CVD method, a thermal CVD method is preferable.

[0078] Examples of the substrate include a silicon substrate, an alumina substrate, a magnesium oxide substrate, a glass substrate, a sapphire substrate, and a stainless substrate.

[0079] The catalyst layer can be formed, for example, by attaching catalyst particles to a substrate by sputtering. Examples of catalysts include metals, specifically iron (Fe), nickel (Ni), cobalt (Co), molybdenum (Mo), gold (Au), and alloys containing at least one metal selected from the group consisting of these. Examples of alloys include iron alloys, nickel alloys, and cobalt alloys. The catalyst may also be a metal precursor, such as a metal oxide or metal compound. Examples of metal oxides include iron oxide, nickel oxide, and cobalt oxide. An example of a metal compound is iron chloride. When using a precursor, it is necessary to convert the precursor to a metal before performing the CVD method, for example, by heating it.

[0080] The catalyst substrate described above may further include a buffer layer between the substrate and the catalyst layer. Examples of materials used for the buffer layer include silica (SiO2), alumina (Al2O3), silicon nitride (SiN), zinc oxide (ZnO), copper oxide (Cu2O), and nickel oxide (NiO). The buffer layer can be formed, for example, by sputtering.

[0081] Sputtering for forming a catalyst layer and sputtering for forming a buffer layer can be carried out using known apparatus and conditions depending on the object to be sputtered. The pressure conditions for sputtering are preferably 0.01 to 10 Pa, more preferably 0.1 to 1 Pa.

[0082] As the raw material gas, carbon-containing raw material gases can be used, and examples include hydrocarbons, sulfur-containing organic gases, phosphorus-containing organic gases, carbon monoxide, and alcohols. Examples of hydrocarbons include alkane compounds such as methane and ethane, alkene compounds such as ethylene and butadiene, alkyne compounds such as acetylene, aryl hydrocarbon compounds such as benzene, toluene, and styrene, aromatic hydrocarbons having condensed rings such as indene, naphthalene, and phenanthrene, cycloalkane compounds such as cyclopropane and cyclohexane, cycloolefin compounds such as cyclopentene, and alicyclic hydrocarbon compounds having condensed rings such as steroids. Examples of alcohols include methanol and ethanol. From the viewpoint of the purity of the resulting CNTs, the raw material gas is preferably hydrocarbons.

[0083] Along with the raw material gas, a carrier gas, which is a gas that transports the raw material gas, may also be supplied to the reaction chamber. Examples of carrier gases include helium, neon, argon, nitrogen, and hydrogen.

[0084] In the CVD process, the temperature inside the reaction chamber is preferably 600 to 850°C, more preferably 650 to 800°C, from the viewpoint of the growth rate of CNTs and the purity of the resulting CNTs. The pressure inside the reaction chamber in the CVD process is preferably atmospheric pressure, from the viewpoint of the growth rate of CNTs and their purity. Depending on other conditions when carrying out the CVD process, the pressure inside the reaction chamber may be reduced or increased from atmospheric pressure.

[0085] The average length of CNTs in the CNT forest is preferably 10 to 1000 μm, more preferably 30 to 800 μm, and even more preferably 50 to 500 μm. The average length of CNTs in the CNT forest can be adjusted, for example, by adjusting the time spent on the CVD method, i.e., the CNT growth time.

[0086] The average diameter of the CNTs is preferably 1 to 50 nm, more preferably 3 to 30 nm, and even more preferably 5 to 15 nm. The average diameter of the CNTs can be adjusted, for example, by adjusting the thickness of the catalyst layer and the type of catalyst.

[0087] The average length and average diameter of a carbon nanotube (CNT) are measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Specifically, ten images of the CNT are obtained using an SEM or TEM. Ten length measurement points are arbitrarily selected from each of the ten images and measured, for a total of 100 lengths. The average length of the CNT is then calculated by arithmetic mean of these 100 length measurements. Similarly, ten diameter measurement points are arbitrarily selected from each of the ten images and measured, for a total of 100 diameter measurements. The average diameter of the CNT is then calculated by arithmetic mean of these 100 diameter measurements.

[0088] The carbon purity (mass%) of CNTs is preferably 95.0 to 99.999%. The lower limit of carbon purity of CNTs is preferably 96.0%, more preferably 97.0%, even more preferably 98.0%, even more preferably 99.0%, and particularly preferably 99.8%. The upper limit of carbon purity of CNTs may be, for example, 99.99% or 99.9%. The carbon purity of CNTs can be determined, for example, by elemental analysis using X-ray fluorescence.

[0089] The crystallinity of carbon nanotubes (CNTs) can be evaluated, for example, using Raman spectroscopy. In Raman spectroscopy, the D / G ratio is used as an indicator. The D / G ratio is defined as 1580 cm⁻¹ in Raman spectroscopy. -1 1360 cm⁻¹ relative to the peak intensity of the G-band appearing in the vicinity -1 This is the ratio of the peak intensities of the D band appearing in the vicinity. A smaller D / G ratio indicates higher crystallinity of the carbon nanotube. The D / G ratio in CNTs is preferably 0.5 to 1.0, more preferably 0.6 to 0.8.

[0090] The purity and crystallinity of CNTs can be adjusted, for example, by controlling the thickness and type of buffer layer, the thickness and type of catalyst layer, the type and flow rate of the raw material gas in the CVD process, and the temperature and pressure in the reaction chamber.

[0091] The CNTs may be single-walled carbon nanotubes or multi-walled carbon nanotubes with two or more layers. From the viewpoint of productivity of CNT films, multi-walled carbon nanotubes are preferred. The number of layers in the multi-walled carbon nanotubes is not particularly limited, but is preferably 2 to 20.

[0092] A CNT web contains multiple CNT fibers. Each of the multiple CNT fibers contains multiple CNTs. A CNT fiber consists of multiple CNTs oriented in one direction. In a CNT fiber, the longitudinal directions of the multiple CNTs are aligned in one direction.

[0093] A CNT web can be manufactured, for example, by using a gripping tool such as tweezers to pull out CNTs located at the ends of a CNT forest, so that they are separated from the CNT forest in a direction parallel to the surface of the substrate on which the CNT forest is provided. When CNTs located at the ends of the CNT forest are pulled out, the CNTs adjacent to the pulled-out CNT are sequentially pulled out by van der Waals forces. The pulled-out CNTs are oriented so that their longitudinal direction is aligned with the direction from which they were pulled. Therefore, the multiple CNTs constituting the CNT fiber are oriented in one direction. The multiple CNTs constituting the CNT fiber are bonded to each other by van der Waals forces. As a result, a CNT web is obtained, which is composed of multiple CNT fibers that extend in the direction from which the CNTs were pulled.

[0094] A CNT web may be manufactured, for example, by bringing a rectangular instrument into contact with the side wall or the upper surface of the end of a CNT forest, which constitutes the CNT forest, and moving the instrument away from the CNT forest in a direction parallel to the surface of the substrate on which the CNT forest is provided.

[0095] An example of a CNT web manufacturing method will be explained using drawings. Figure 1 is a top view illustrating the process of manufacturing a CNT web 50 using a CNT forest 42 provided on a substrate 40, and Figure 2 is a cross-sectional view taken along line AA in Figure 1.

[0096] The CNT web 50 shown in Figures 1 and 2 can be manufactured by pulling out a plurality of CNTs located at the ends of a CNT forest 42, which is provided on a substrate 40 and oriented perpendicular to the surface of the substrate 40, in a sheet-like manner in a direction parallel to the surface of the substrate 40, away from the CNT forest 42. When the CNT web 50 is viewed from above, the CNT fibers 52 constituting the CNT web 50 extend along the direction in which the CNTs are pulled out, and the plurality of CNT fibers 52 are aligned perpendicular to this direction.

[0097] A CNT film may also be obtained by winding a CNT web 50, manufactured by drawing multiple CNTs in parallel from a CNT forest 42, onto a roller 60 and laminating the CNT web 50.

[0098] The carbon nanotube film content in the prepreg is preferably 0.01 to 80% by mass, more preferably 0.05 to 75% by mass, even more preferably 0.1 to 70% by mass, even more preferably 0.2 to 65% by mass, and even more preferably 0.3 to 65% by mass, based on the total amount of prepreg. Having the carbon nanotube film content within this range results in a fiber-reinforced composite material with excellent strength.

[0099] In particular, when carbon nanotube film is included as the main reinforcing fiber of the prepreg, the carbon nanotube film content in the prepreg is preferably 35 to 80% by mass, more preferably 40 to 80% by mass, even more preferably 45 to 80% by mass, even more preferably 50 to 75% by mass, even more preferably 50 to 70% by mass, even more preferably 55 to 70% by mass, and even more preferably 55 to 65% by mass, based on the total amount of prepreg. Having the carbon nanotube film content within the above range results in a fiber-reinforced composite material with excellent strength. When carbon nanotube film is included as the main reinforcing fiber of the prepreg, it is preferable that it substantially contains no other reinforcing fibers other than carbon nanotube film, and it is preferable that the reinforcing fibers contained in the prepreg of the present invention consist solely of carbon nanotube film.

[0100] In particular, the carbon nanotube film content in the prepreg containing the carbon fiber sheet described later is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, even more preferably 0.1 to 2.0% by mass, even more preferably 0.2 to 1.0% by mass, and even more preferably 0.3 to 0.7% by mass, based on the total amount of the prepreg. Having the carbon nanotube film content within this range results in a fiber-reinforced composite material with excellent strength.

[0101] <Carbon Fiber Sheet and Prepreg Containing a Carbon Fiber Sheet> The prepreg of the present invention contains a resin composition and a carbon nanotube film, but preferably also contains a carbon fiber sheet. That is, the prepreg of the present invention is a prepreg containing a resin composition, a carbon nanotube film and a carbon fiber sheet, wherein the resin composition is impregnated into the carbon nanotube film and the carbon fiber sheet, the resin composition contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm² 2 Therefore, it is preferable that the carbon nanotube film is a carbon nanotube web laminate.

[0102] The carbon fiber sheet can take the form of a tape, mat, or fabric in which carbon fibers are arranged in a specific direction, with a tape in which carbon fibers are arranged in a specific direction being more preferable. Multiple forms of carbon fiber sheets may be used in combination. Examples of carbon fibers constituting the carbon fiber sheet include carbon fibers, graphite fibers, and graphite whiskers. These are preferably manufactured using polyacrylonitrile fibers, cellulosic fibers, pitch, aromatic hydrocarbons, and carbon black as raw materials. Carbon fibers may be used alone or in appropriate mixtures of two or more types.

[0103] When the prepreg contains a carbon fiber sheet, the total content of the carbon fiber sheet and carbon nanotube film in the prepreg is preferably 40 to 85% by mass, more preferably 45 to 80% by mass, even more preferably 50 to 75% by mass, even more preferably 55 to 75% by mass, and even more preferably 60 to 70% by mass, based on the total amount of the prepreg. Having the carbon nanotube film content within this range results in a fiber-reinforced composite material with excellent strength. When the carbon fiber sheet and carbon nanotube film are included as the main reinforcing fibers in the prepreg, it is preferable that it substantially contains no other reinforcing fibers other than the carbon fiber sheet and carbon nanotube film, and it is preferable that the reinforcing fibers contained in the prepreg of the present invention consist only of the carbon fiber sheet and carbon nanotube film.

[0104] The mass ratio of carbon nanotube film content to carbon fiber sheet content in the prepreg [carbon nanotube film / carbon fiber sheet] is preferably 0.001 to 0.2, more preferably 0.004 to 0.1, even more preferably 0.006 to 0.05, and even more preferably 0.008 to 0.02. By having the mass ratio of carbon fiber sheet content to carbon nanotube film content within the above range, the resulting fiber-reinforced composite material will have excellent strength.

[0105] [Method for Manufacturing Prepregs] The method for manufacturing the prepreg of the present invention is not particularly limited as long as it contains the resin composition and the carbon nanotube film, but it is preferable to manufacture it by the method shown below. That is, the method for manufacturing the prepreg of the present invention is preferably a method for manufacturing a prepreg containing a resin composition containing a radical polymerization-type thermosetting oligomer and a polymerization initiator, and a carbon nanotube film, comprising the steps of impregnating the carbon nanotube film with the resin composition, or impregnating the carbon nanotube film with a liquid composition containing the raw materials for the radical polymerization-type thermosetting oligomer and the polymerization initiator, and aging it at 30 to 90°C to obtain a resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate.

[0106] As described above, there are two suitable methods for producing prepregs: a method comprising the step of impregnating a carbon nanotube film with a resin composition (resin composition impregnation method), and a method comprising the step of impregnating a carbon nanotube film with a liquid composition containing the raw materials for a radical polymerization-type thermosetting oligomer and the polymerization initiator (liquid composition impregnation method). Each of these will be described below.

[0107] <Method for impregnating with resin composition> The method for producing a prepreg by this method preferably includes a resin composition containing a radical polymerization-type thermosetting oligomer and a polymerization initiator, and a carbon nanotube film, comprising the step of impregnating the carbon nanotube film with the resin composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate.

[0108] In this method, the resin composition is applied to a flat substrate, the carbon nanotube film is placed on top of it, and then another flat substrate, or a substrate coated with the resin composition as described above, is placed on the surface of the carbon nanotube film to sandwich the carbon nanotube film. After pressing from both sides, the resin composition is impregnated into the carbon nanotube film. After that, it is aged as needed to obtain a sheet-like prepreg. Alternatively, the resin composition is dissolved in a volatile solvent, sprayed onto the carbon nanotube film to impregnate it, and then dried. After that, it is aged as needed to obtain a sheet-like prepreg.

[0109] The flat substrate can preferably be a release liner or a release resin that can hold the prepreg and, if necessary, peel it off from the prepreg. The volatile solvent is not limited as long as it can dissolve the resin composition and be removed by the drying process, but a ketone solvent is preferred.

[0110] <Liquid Composition Impregnation Method> The method for producing a prepreg by this method preferably includes the steps of impregnating the carbon nanotube film with a liquid composition containing the raw materials for the radical polymerization-type thermosetting oligomer and the polymerization initiator, and aging it at 30 to 90°C to obtain a resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate.

[0111] In this method, a liquid composition containing isocyanate compounds, hydroxyalkyl (meth)acrylates, epoxy resins, unsaturated basic acids, dicarboxylic acids, diols, etc., which are raw materials for the radical polymerization-based thermosetting oligomer, and a polymerization initiator is sprayed onto the carbon nanotube film to impregnate it, and then aged at 30 to 90°C to obtain a resin composition from the liquid composition. This yields a sheet-like prepreg in which the resin composition is impregnated into the carbon nanotube film. The aging temperature is preferably 30 to 90°C, more preferably 40 to 80°C, and even more preferably 40 to 70°C. According to this method, a resin composition containing the target radical polymerization-based thermosetting oligomer can be efficiently obtained.

[0112] <Method for Manufacturing a Prepreg Containing a Carbon Fiber Sheet> The prepreg of the present invention contains a resin composition and a carbon nanotube film, but as described above, it is preferable to also contain a carbon fiber sheet. The method for manufacturing the prepreg containing a carbon fiber sheet is not particularly limited as long as it contains the resin composition, the carbon nanotube film and the carbon fiber sheet, but it is preferable to manufacture it by the method shown below. That is, the method for manufacturing a prepreg containing a carbon fiber sheet is preferably a method for manufacturing a prepreg containing a resin composition containing a radical polymerization-type thermosetting oligomer and a polymerization initiator, a carbon nanotube film and a carbon fiber sheet, comprising the steps of impregnating the carbon nanotube film and the carbon fiber sheet with the resin composition, or impregnating the carbon nanotube film and the carbon fiber sheet with a liquid composition containing the raw materials for the radical polymerization-type thermosetting oligomer and the polymerization initiator, and aging at 30 to 90°C to obtain the resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 Therefore, the carbon nanotube film is a carbon nanotube web laminate.

[0113] As described above, there are two suitable methods for manufacturing prepregs. One is a method comprising the step of impregnating a resin composition into a carbon nanotube film and a carbon fiber sheet (resin composition impregnation method), and the other is a method comprising the step of impregnating a carbon nanotube film and a carbon fiber sheet with a liquid composition containing the raw materials for a radical polymerization-type thermosetting oligomer and the polymerization initiator (liquid composition impregnation method). Each of these methods will be described below.

[0114] (Resin composition impregnation method) The method for producing a prepreg by this method preferably comprises a resin composition containing a radical polymerization thermosetting oligomer and a polymerization initiator, a carbon nanotube film, and a carbon fiber sheet, and includes a step of impregnating the carbon nanotube film and the carbon fiber sheet with the resin composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate.

[0115] In this method, the resin composition is applied to a flat substrate, and the carbon nanotube film and carbon fiber sheet are placed on top of it. Then, another flat substrate, or a substrate coated with the resin composition as described above, is placed on the side opposite to the side in contact with the resin composition, sandwiching the carbon nanotube film and carbon fiber sheet between the substrates. Pressure is then applied from both sides to impregnate the carbon nanotube film and carbon fiber sheet with the resin composition. After that, the mixture is aged as needed to obtain a sheet-like prepreg. Alternatively, the resin composition is dissolved in a volatile solvent, sprayed onto the carbon nanotube film to impregnate it, and then dried. After that, the mixture is aged as needed to obtain a sheet-like prepreg. When layering the carbon nanotube film and carbon fiber sheet, either one may be placed first.

[0116] The flat substrate can preferably be a release liner or a release resin that can hold the prepreg and, if necessary, peel it off from the prepreg. The volatile solvent is not limited as long as it can dissolve the resin composition and be removed by the drying process, but a ketone solvent is preferred.

[0117] (Liquid composition impregnation method) The method for producing a prepreg by this method preferably includes the steps of impregnating the carbon nanotube film and the carbon fiber sheet with a liquid composition containing the raw materials for the radical polymerization thermosetting oligomer and the polymerization initiator, and aging it at 30 to 90°C to obtain a resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate.

[0118] In this method, a liquid composition containing isocyanate compounds, hydroxyalkyl (meth)acrylates, epoxy resins, unsaturated basic acids, dicarboxylic acids, diols, etc., which are raw materials for the radical polymerization-based thermosetting oligomer, and a polymerization initiator is sprayed onto the carbon nanotube film and the carbon fiber sheet to impregnate them, and then aged at 30 to 90°C to obtain a resin composition from the liquid composition. This yields a sheet-like prepreg in which the resin composition has been impregnated into the carbon nanotube film and the carbon fiber sheet. The aging temperature is preferably 30 to 90°C, more preferably 40 to 80°C, and even more preferably 40 to 70°C. According to this method, a resin composition containing the target radical polymerization-based thermosetting oligomer can be efficiently obtained.

[0119] [Fiber-reinforced composite molded articles] The fiber-reinforced composite molded articles of the present invention are obtained by molding the prepreg. Therefore, the fiber-reinforced composite molded articles of the present invention have excellent strength. There are no restrictions on the molding method, but the prepreg is cut as needed, charged into a mold, heated under pressure, and cured to obtain the molded article. Because the fiber-reinforced composite molded articles of the present invention have excellent strength, they can be suitably used in applications that require particularly high strength.

[0120] The following describes an embodiment of the present invention in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0121] [Manufacturing of Carbon Nanotube Films] Manufacturing Example 1 (Manufacturing of Carbon Nanotube Forests) A wafer coated with a catalyst for carbon nanotube growth was prepared, and vertically oriented carbon nanotubes were grown from the catalyst by chemical vapor deposition to produce a vertically oriented carbon nanotube forest oriented perpendicular to the wafer. The carbon nanotubes constituting the carbon nanotube forest were multi-walled carbon nanotubes, with an average length of 250 μm per nanotube, an average diameter of 6 to 10 nm, a carbon purity of 99.8% or higher, and a crystallinity (D / G ratio) of 0.6 to 0.8.

[0122] (Manufacturing of Carbon Nanotube Film (Carbon Nanotube Web Laminate)) From the carbon nanotube forest formed on the catalyst substrate, several carbon nanotubes located at the ends were picked up with a picking tool and pulled out in a sheet form. In this way, one layer of carbon nanotube web was prepared. On the carbon nanotube web, another layer of carbon nanotube web was formed in the same manner, creating a two-layer carbon nanotube web. The same operation was repeated to obtain a carbon nanotube web laminate (carbon nanotube film) in which 50 layers of carbon nanotube webs were stacked. The basis weight of the carbon nanotube film was 0.17 mg / cm². 2 That was the case.

[0123] [Preparation of Liquid Composition] In Production Examples 2 to 11, the components listed in Table 1 were mixed uniformly in the ratios (parts by mass) listed in Table 1 to obtain a liquid composition. The liquid composition immediately after mixing was used in the following sections: [Evaluation of Impregnation Claims of Liquid Composition], [Preparation of Prepreg], and [Preparation of Prepreg (Prepreg containing Carbon Nanotube Film and Carbon Fiber Sheet)]. In other words, the "liquid composition obtained in Production Examples 2 to 11" or "liquid composition of Production Examples 2 to 11" in the following sections: [Evaluation of Impregnation Claims of Liquid Composition], [Preparation of Prepreg], and [Preparation of Prepreg (Prepreg containing Carbon Nanotube Film and Carbon Fiber Sheet)] refers to the liquid composition immediately after obtaining it by the method described above.

[0124] [Physical Properties of Resin Compositions] (1) Aromatic Kernel Concentration of Resin Compositions In the present invention, the aromatic kernel concentration of the resin composition is the number of moles of aromatic rings (benzene rings, etc.) contained in 1 kg of the resin composition (all raw materials of the resin composition). The number of moles of aromatic rings of compounds having a polycyclic structure is obtained by multiplying the number of rings by the number of moles of the compound. For example, the naphthalene skeleton has 2 rings, the anthracene skeleton has 3 rings, and the biphenyl skeleton has 2 rings. Table 1 shows the aromatic kernel concentrations of the resin compositions obtained from the liquid compositions of Production Examples 2 to 11. Table 1 also shows the aromatic kernel concentration of the radical polymerization-based thermosetting oligomer, which is a component of the resin composition; the aromatic kernel concentration of the polymerizable monomer; the aromatic kernel concentration derived from the radical polymerization-based thermosetting oligomer in the aromatic kernel concentration of the resin composition; and the aromatic kernel concentration derived from the polymerizable monomer in the aromatic kernel concentration of the resin composition.

[0125] (2) Acrylic equivalent of radical polymerization thermosetting oligomers The acrylic equivalent (g / eq) of radical polymerization thermosetting oligomers was determined by dividing the total amount (g) of raw material components of the radical polymerization thermosetting oligomer by the total number of moles of (meth)acryloyl groups contained in the raw material components of the radical polymerization thermosetting oligomer. Table 1 shows the acrylic equivalent of radical polymerization thermosetting oligomers contained in the resin compositions obtained from the liquid compositions of Production Examples 2 to 11.

[0126] (3) Viscosity of the resin compositions The liquid compositions of Production Examples 2 to 11 were aged at 50°C for 72 hours to obtain the resin compositions. The viscosity of the resin compositions was measured at 80°C using a cone plate viscometer (manufactured by MST Engineering Co., Ltd.). Table 1 shows the viscosity of each resin composition obtained from the liquid compositions of Production Examples 2 to 11.

[0127]

[0128] [Preparation of Pre-resin Composition] Production Example 12 In a reaction vessel, 421.4 parts of isophorone diisocyanate (manufactured by Evonik), 100.0 parts of diethylene glycol dimethacrylate (NK Ester 2G, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 199.9 parts of styrene, 0.02 parts of dibutyltin dilaurate, 76.03 parts of 1,3-propanediol (manufactured by DuPont), 202.4 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Corporation), 0.04 parts of toluhydroquinone, and 0.21 parts of dibutylhydroxytoluene were charged. The mixture was heated under an airflow and reacted at 105-115°C for 3 hours to obtain a pre-resin composition containing urethane (meth)acrylate. Absorption of isocyanate groups by IR (2270 m －１ The reaction was considered complete when the (nearby) level became constant.

[0129] Production Example 13 510.2 parts of isophorone diisocyanate (manufactured by Evonik), 150.0 parts of diethylene glycol dimethacrylate (NK Ester 2G, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 93.8 parts of 1,3-propanediol (manufactured by DuPont), 245.7 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Corporation), 0.04 parts of toluhydroquinone, and 0.26 parts of dibutylhydroxytoluene were charged into a reaction vessel. The mixture was heated under an airflow and reacted at 105-115°C for 3 hours to obtain a preliminary resin composition containing urethane (meth)acrylate. Absorption of isocyanate groups by IR (2270 m －１ The reaction was considered complete when the (nearby) level became constant.

[0130] [Evaluation of the Impregnation Properties of the Liquid Composition Claim] The liquid compositions of Production Examples 2 to 11 were measured at a basis weight of 0.17 mg / cm² in a 50 mm square area.2 A 0.02 g (1 drop) of the liquid composition was added to a carbon nanotube film using a dropper, and the area of ​​penetration was measured after 10 minutes. The results are shown in Table 2. A larger penetration area indicates superior impregnation and a higher affinity between the liquid composition and the resin composition obtained from the liquid composition and the carbon nanotubes.

[0131]

[0132] [Prepreg Production] 0.10 g of the liquid composition obtained in Examples 1-8 and Comparative Examples 1 and 2, and in Production Examples 2-11, is added to the same amount as in Production Example 1, which had a basis weight of 0.17 mg / cm². 2 A carbon nanotube-containing prepreg was obtained by impregnating a 30 cm square carbon nanotube film with the material and then aging it at 50°C for 72 hours to oligomerize it on the fibers. The composition of the obtained prepreg was approximately 40% by mass of the resin composition and approximately 60% by mass of the carbon nanotube film.

[0133] Example 9 A resin composition was obtained by mixing 1.5 parts by mass of perbutyl E (t-butylperoxy-2-ethylhexyl monocarbonate, 10-hour half-life temperature 99.0°C), a polymerization initiator, with 100 parts by mass of the preliminary resin composition obtained in Production Example 1. The aromatic kernel concentration of the obtained resin composition was 1.89 mol / kg. The composition of the resin composition was the same as in Example 1. The resin composition was diluted with acetone until its mass doubled. This was then mixed with the 30 cm square carbon nanotube film (basis weight 0.17 mg / cm²) obtained in Production Example 1. 2 0.20 g was impregnated into the material. Then, a carbon nanotube prepreg was obtained by letting it stand in a dryer heated to 90°C for 10 minutes. The composition of the obtained prepreg was approximately 40% by mass of resin composition and approximately 60% by mass of carbon nanotubes.

[0134] Comparative Example 3 A resin composition was obtained by mixing 1.5 parts by mass of perbutyl E (t-butylperoxy-2-ethylhexyl monocarbonate, 10-hour half-life temperature 99.0°C), a polymerization initiator, with 100 parts by mass of the preliminary resin composition obtained in Production Example 13. The aromatic kernel concentration of the obtained resin composition was 0.001 mol / kg. The composition of the resin composition was the same as in Comparative Example 1. The resin composition was diluted with acetone until its mass doubled. This was then mixed with the 30 cm square carbon nanotube film (basis weight 0.17 mg / cm²) obtained in Production Example 1. 2 0.20 g was impregnated into the material. Then, a carbon nanotube prepreg was obtained by letting it stand in a dryer heated to 90°C for 10 minutes. The composition of the obtained prepreg was approximately 40% by mass of resin composition and approximately 60% by mass of carbon nanotubes.

[0135] [Prepreg Production (Prepreg containing carbon nanotube film and carbon fiber sheet)] Examples 10-17 and Comparative Examples 4 and 5 Carbon fibers (TORAYCA T700S, manufactured by Toray Industries, Inc.) were aligned in one direction and the basis weight was 20 mg / cm² 2 A 30 cm square carbon fiber sheet and a basis weight of 0.17 mg / cm² obtained in Manufacturing Example 1 were used. 2 A prepreg containing carbon nanotube film and carbon fiber sheet was obtained by stacking 30 cm square carbon nanotube films, impregnating them with 10.21 g of the liquid composition obtained in Production Examples 2 to 11, and then aging them at 50°C for 72 hours to oligomerize them on the fibers. The composition of the obtained prepreg was approximately 36% by mass of the resin composition and approximately 64% by mass of the carbon nanotube film and carbon fiber sheet combined.

[0136] Example 18 A resin composition was obtained by mixing 1.5 parts by mass of perbutyl E (t-butylperoxy-2-ethylhexyl monocarbonate, 10-hour half-life temperature 99.0°C), which is a polymerization initiator, with 100 parts by mass of the preliminary resin composition obtained in Production Example 12. The aromatic kernel concentration of the obtained resin composition was 1.89 mol / kg. The composition of the resin composition was the same as in Example 1. 113 g / m² of the resin was applied to release paper using a roll coater heated to 80°C.2 The resin composition was applied uniformly to create a coating film. Next, carbon fibers (TORAYCA T700S, manufactured by Toray Industries, Inc.) were aligned in one direction, and the basis weight was set to 20 mg / cm². 2 A 30 cm square carbon fiber sheet and the basis weight 0.17 mg / cm obtained in Manufacturing Example 1 2 A 30 cm square carbon nanotube film was placed on top of a 30 cm square release paper coating, and a new release paper was laminated on top of it. Then, it was passed through a roller heated to 90°C and pressure was applied to impregnate the carbon fiber sheet and carbon nanotube film with the resin composition. One of the release papers was peeled off, and a polyethylene film was laminated to obtain a prepreg containing the carbon nanotube film and carbon fiber sheet. The obtained prepreg contained approximately 36% by mass of the resin composition and approximately 64% by mass of the carbon nanotube film and carbon fiber sheet combined.

[0137] Comparative Example 6 A resin composition was obtained by mixing 1.5 parts by mass of perbutyl E (t-butylperoxy-2-ethylhexyl monocarbonate, 10-hour half-life temperature 99.0°C), a polymerization initiator, with 100 parts by mass of the preliminary resin composition obtained in Production Example 13. The aromatic kernel concentration of the obtained resin composition was 0.001 mol / kg. The composition of the resin composition was the same as in Comparative Example 1. 113 g / m² of the resin was applied to the release paper using a roll coater heated to 80°C. 2 The resin composition was applied uniformly to create a coating film. Next, carbon fibers (TORAYCA T700S, manufactured by Toray Industries, Inc.) were aligned in one direction, and the basis weight was set to 20 mg / cm². 2 A 30 cm square carbon fiber sheet and the basis weight 0.17 mg / cm obtained in Manufacturing Example 1 2A 30 cm square carbon nanotube film was placed on top of a 30 cm square release paper coating, and a new release paper was laminated on top of it. Then, it was passed through a roller heated to 90°C and pressure was applied to impregnate the carbon fiber sheet and carbon nanotube film with the resin composition. One of the release papers was peeled off, and a polyethylene film was laminated to obtain a prepreg containing the carbon nanotube film and carbon fiber sheet. The obtained prepreg contained approximately 36% by mass of the resin composition and approximately 64% by mass of the carbon nanotube film and carbon fiber sheet combined.

[0138] [Evaluation of Prepregs] (1) Tensile strength of molded products <Preparation of molded sheets> One sheet of prepreg (prepreg containing carbon nanotube film) obtained in Examples 1 to 9 and Comparative Examples 1 to 3 was molded using an autoclave molding machine (DL-2010, manufactured by Hanyuda Iron Works Co., Ltd.). The molding temperature was 135°C, the molding pressure was 7 bar, the heating rate was 3°C / min, and the molding time after reaching the maximum temperature was 10 minutes. The thickness of the obtained molded sheets was 0.003 to 0.006 mm.

[0139] <Tensile Strength> The molded plate obtained in <Preparation of Molded Plate> above was cut to 120 mm x 15 mm, and tabs were glued to the top and bottom 30 mm to obtain a tensile test specimen. A tensile test was performed on the obtained specimen. The tensile test speed was set to 1 mm / min. The results are shown in Table 3.

[0140] (2) Interlaminar shear strength of molded product <Preparation of molded plate> Twelve prepregs (prepregs containing carbon nanotube film and carbon fiber sheet) obtained in Examples 10 to 18 and Comparative Examples 4 to 6 were stacked and molded using a 100-ton hydraulic press (manufactured by Toho Press Works Co., Ltd.). The molding temperature was 135°C, the molding pressure was 0.7 MPa, and the molding time was 7 minutes. The thickness of the obtained molded plate was approximately 2 mm.

[0141] <Interlaminar Shear Strength> The interlaminar shear strength was measured on the obtained test specimens in accordance with JIS K 7078:1991. The results are shown in Table 3.

[0142]

[0143] Table 3 shows that the molded plates obtained by molding the prepreg containing the carbon nanotube film of the example exhibit high tensile strength. Furthermore, the molded plates obtained by molding the prepreg containing both the carbon nanotube film and the carbon fiber sheet of the example exhibit high interlaminar shear strength. This indicates that the fiber-reinforced composite material obtained from the prepreg of the present invention has excellent strength. Thus, the prepreg of the present invention can produce a fiber-reinforced composite material with excellent strength, making it useful as a molding material in various fields requiring high strength.

[0144] 40...Substrate 42...CNT forest 50...CNT web drawn from the CNT forest 52...CNT fibers that make up the CNT web 60...Roller

Claims

1. A prepreg containing a resin composition and a carbon nanotube film, wherein the resin composition is impregnated into the carbon nanotube film, the resin composition contains a radical polymerization-based thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate, and the prepreg is such that 2. The prepreg according to claim 1, wherein the resin composition further contains a polymerizable monomer.

3. The prepreg according to claim 1 or 2, wherein the radical polymerization-based thermosetting oligomer is a urethane (meth)acrylate, and the urethane (meth)acrylate has structural units derived from a compound having two or more isocyanate groups and structural units derived from a hydroxyalkyl (meth)acrylate.

4. The prepreg according to any one of claims 1 to 3, wherein the carbon nanotube web consists of a plurality of carbon nanotube fibers, and the plurality of carbon nanotube fibers are aligned in the same direction.

5. The prepreg according to any one of claims 2 to 4, wherein the polymerizable monomer contains at least one selected from the group consisting of styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and ethoxylated-o-phenylphenol acrylate.

6. The prepreg according to any one of claims 3 to 5, wherein the acrylic equivalent of the radical polymerization-based thermosetting oligomer is 200 to 1600 g / eq.

7. The prepreg according to any one of claims 1 to 6, wherein the polymerization initiator has a 10-hour half-life temperature of 45 to 130°C.

8. The prepreg according to any one of claims 2 to 7, wherein the content of the polymerizable monomer in the resin composition is 1 to 60% by mass.

9. The prepreg according to any one of claims 3 to 8, wherein the compound having two or more isocyanate groups is an aromatic isocyanate compound.

10. The prepreg according to any one of claims 1 to 9, wherein the aromatic kernel concentration of the resin composition is 1.0 to 3.0 mol / kg.

11. A prepreg containing a resin composition, a carbon nanotube film, and a carbon fiber sheet, wherein the resin composition is impregnated into the carbon nanotube film and the carbon fiber sheet, the resin composition contains a radical polymerization-type thermosetting oligomer and a polymerization initiator, the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 The carbon nanotube film is a carbon nanotube web laminate, and the prepreg is such that 12. The prepreg according to any one of claims 1 to 11, wherein the viscosity of the resin composition at 80°C is 0.1 to 30 Pa·s.

13. A fiber-reinforced composite material molded article obtained by molding a prepreg according to any one of claims 1 to 12.

14. A method for producing a resin composition containing a radical polymerization-type thermosetting oligomer and a polymerization initiator, and a prepreg containing a carbon nanotube film, comprising the steps of: impregnating the carbon nanotube film with the resin composition; or impregnating the carbon nanotube film with a liquid composition containing the raw materials for the radical polymerization-type thermosetting oligomer and the polymerization initiator, and aging it at 30 to 90°C to obtain the resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 A method for manufacturing a prepreg, wherein the carbon nanotube film is a carbon nanotube web laminate.

15. A method for producing a prepreg containing a resin composition containing a radical polymerization-type thermosetting oligomer and a polymerization initiator, a carbon nanotube film, and a carbon fiber sheet, comprising the steps of: impregnating the carbon nanotube film and the carbon fiber sheet with the resin composition; or impregnating the carbon nanotube film and the carbon fiber sheet with a liquid composition containing the raw materials for the radical polymerization-type thermosetting oligomer and the polymerization initiator, and aging at 30 to 90°C to obtain the resin composition from the liquid composition, wherein the aromatic kernel concentration of the resin composition is 0.1 mol / kg or more, and the basis weight of the carbon nanotube film is 0.0226 to 170 mg / cm². 2 A method for manufacturing a prepreg in which the carbon nanotube film is a carbon nanotube web laminate.

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