JP2021107470A - Fiber-reinforced composite material, and method for producing the same - Google Patents

Abstract

To provide a fiber-reinforced composite material excellent in shock resistance and plasticity.SOLUTION: There is provided [A] A fiber-reinforced composite material which is obtained by impregnating a fiber layer comprising a reinforcement fiber with a matrix resin composition. The fiber-reinforced composite material is such that: the matrix resin composition is a matrix resin composition which comprises at least [B] an epoxy resin, [C] thermoplastic resin particles and [D] an inorganic additive having Mohs hardness of 6 or more, and satisfies a formula (1). 0<a blending amount of [D] of the matrix resin composition/a blending amount of [C] of the matrix resin composition<0.6 ... a formula (1). The [B] epoxy resin is preferably an epoxy resin having epoxy groups of at least two functionalities. The [C] thermoplastic resin particles are preferably polyamide particles. A content of the [D] inorganic additive is preferably 0.0001-5 pts.mass based on 100 pts.mass of the [B] epoxy resin.SELECTED DRAWING: None

Description

The present invention relates to a fiber-reinforced composite material having excellent impact resistance and toughness, and a method for producing the same.

A fiber-reinforced composite material (simply called a composite material or FRP) composed of a reinforcing fiber and a matrix resin has features such as light weight, high strength, and high elastic modulus, and is used in aircraft, automobiles, sports / leisure, and general industries. Widely applied. As the matrix resin, a thermosetting resin or a thermoplastic resin is used. In particular, thermosetting resins, especially epoxy resins, are widely used because of their high degree of molding freedom due to their tackiness and drapeability. Since the epoxy resin generally has low toughness, when the epoxy resin is used as the matrix resin, there is a problem that the toughness and impact resistance of the obtained fiber-reinforced composite material are lowered. In particular, in transportation equipment applications such as aircraft and automobiles, composite materials are required to have particularly high toughness and impact resistance. Therefore, techniques for improving these mechanical properties have been studied.

For example, Patent Document 1 proposes a method of arranging thermoplastic resin particles between prepreg layers as a method of improving impact resistance. Further, Patent Document 2 proposes a method of improving mechanical properties such as impact resistance by changing the resin composition on the surface and inside of the prepreg. However, the toughness and impact resistance of the composite materials obtained by these techniques have not yet been sufficient.

Japanese Unexamined Patent Publication No. 10-231372 Japanese Unexamined Patent Publication No. 8-176325

An object of the present invention is to provide a fiber-reinforced composite material having excellent impact resistance and toughness.

The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material obtained by impregnating a fiber layer composed of [A] reinforcing fibers with a matrix resin composition, wherein the matrix resin composition is at least [B] epoxy resin, [ A fiber-reinforced composite material which is a matrix resin composition composed of C] thermoplastic resin particles and [D] an inorganic additive having a Morse hardness of 6 or more, and is a matrix resin composition satisfying the formula (1).
0 <Mixing amount of matrix resin composition of [D] / Mixing amount of matrix resin composition of [C] <0.6 ... Equation (1)

In the present invention, the [B] epoxy resin is preferably an epoxy resin having at least bifunctional or higher functional epoxy groups. Further, the [C] thermoplastic resin particles are preferably polyamide particles. In the present invention, the content of the [D] inorganic additive is preferably 0.0001 to 5 parts by mass with respect to 100 parts by mass of the [A] epoxy resin.

The fiber-reinforced composite material of the present invention has excellent toughness and impact resistance. Therefore, the fiber-reinforced composite material of the present invention can be preferably used in a wide range of fields such as aircraft, automobiles, sports / leisure, and general industries.

The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material in which a fiber layer made of [A] reinforcing fibers is impregnated with a matrix resin composition, and the matrix resin composition is at least [B] epoxy resin, [ A matrix resin composition comprising C] thermoplastic resin particles and [D] an inorganic additive having a Morse hardness of 6 or more. It is a fiber reinforced composite material.

When the matrix resin composition contains [C] thermoplastic resin particles, when the matrix resin composition invades the fiber layer, the resin particles cannot enter the inside of the fiber layer and are filtered onto the surface of the fiber layer. Therefore, the resin particles are dispersed in the resin layer between the fibers of the fiber-reinforced composite material. (Hereinafter, these dispersed particles are also referred to as "interlayer particles"). The interlayer particles suppress the propagation of impact on the fiber-reinforced composite material. As a result, the impact resistance of the obtained composite material is improved.

Further, in the present invention, the matrix resin is a matrix resin composition satisfying the formula (1).
0 <Mixing amount of matrix resin composition of [D] / Mixing amount of matrix resin composition of [C] <0.6 ... Equation (1)

Further, when the ratio of [C] thermoplastic resin particles and [D] inorganic additive having a Mohs hardness of 6 or more is within this range, the tackiness of the uncured matrix resin is excellent, and at the same time, the fluidity of the resin is fluid. Can be given. As a result, a resin layer having an appropriate thickness is formed between the fiber layers of the cured fiber-reinforced composite material. By forming a resin layer having an appropriate thickness between the fiber layers of the fiber-reinforced composite material, the impact resistance and toughness of the fiber-reinforced composite material are further improved. The blending amount of the matrix resin composition of [D] / the blending amount of the matrix resin composition of [C] ([D] / [C]) is more preferably 0.01 to 0.5. From the viewpoint of improving the interlayer toughness of the obtained fiber-reinforced composite material, it is more preferably 0.15 to 0.4, and from the viewpoint of impact resistance, it is further preferably 0.02 to 0.1. preferable. The thickness of the resin layer is preferably 10 to 50 μm, more preferably 20 to 40 μm, from the viewpoint of toughness and impact resistance of the fiber-reinforced composite material.

In the present invention, the content of the [D] inorganic additive is preferably 0.0001 to 5 parts by mass with respect to 100 parts by mass of the [A] epoxy resin.

Such a fiber-reinforced composite material of the present invention is excellent in toughness and impact resistance. Therefore, the fiber-reinforced composite material of the present invention can be preferably used in a wide range of fields such as aircraft, automobiles, sports / leisure, and general industries.

Each component and the manufacturing method of the fiber-reinforced composite material of the present invention will be described in more detail below.

(1) [A] Reinforcing fiber The reinforcing fiber used in the present invention is not particularly limited, and is, for example, carbon fiber, glass fiber, aramid fiber, silicon carbide fiber, polyester fiber, ceramic fiber, alumina fiber, boron fiber, metal. Examples include fibers, mineral fibers, rock fibers and slug fibers.

Among these reinforcing fibers, carbon fiber, glass fiber, and aramid fiber are preferable. Carbon fiber is more preferable because it has good specific strength and specific elastic modulus, and a lightweight and high-strength fiber-reinforced composite material can be obtained. Polyacrylonitrile (PAN) -based carbon fibers are particularly preferable in terms of excellent tensile strength.

When a PAN-based carbon fiber is used as the reinforcing fiber, its tensile elastic modulus is preferably 100 to 600 GPa, more preferably 200 to 500 GPa, and particularly preferably 230 to 450 GPa. The tensile strength is preferably 2000 MPa to 10000 MPa, more preferably 3000 to 8000 MPa. The diameter of the carbon fiber is preferably 4 to 20 μm, more preferably 5 to 10 μm. By using such carbon fibers, the mechanical properties of the obtained fiber-reinforced composite material can be improved.

The reinforcing fiber may be a bundle of reinforcing fibers, or may be used as a reinforcing fiber sheet in which the reinforcing fibers are formed in a sheet shape. It is preferable to form it in a sheet shape and use it. Examples of the reinforcing fiber sheet include a sheet in which a large number of reinforcing fibers are arranged in one direction, a bidirectional woven fabric such as plain weave and twill weave, a multi-axis woven fabric, a non-woven fabric, a mat, a knit, a braid, and a paper made from reinforcing fibers. Can be mentioned. Among these, it is preferable to use a unidirectionally aligned sheet, a bidirectional woven fabric, or a multi-axis woven fabric base material in which reinforcing fibers are formed into a sheet as continuous fibers because a fiber-reinforced composite material having more excellent mechanical properties can be obtained. The thickness of the sheet-shaped reinforcing fiber base material is preferably 0.01 to 3 mm, more preferably 0.1 to 1.5 mm.

The content of the reinforcing fibers in the fiber-reinforced composite material is preferably in the range of 10 to 90% by volume, more preferably in the range of 15 to 60% by volume.

(2) Matrix Resin Composition (2-1) [B] Epoxy Resin The [B] epoxy resin used in the present invention is not particularly limited, and known epoxy resins can be used. In the present invention, the [B] epoxy resin is preferably an epoxy resin having at least bifunctional or higher functional epoxy groups.

[B] Examples of the epoxy resin include a glycidyl ether type epoxy resin obtained from a compound having a hydroxyl group in the molecule and epichlorohydrin, and a glycidylamine type obtained from a compound having an amino group in the molecule and epichlorohydrin. Epoxy resins, glycidyl ester-type epoxy resins obtained from compounds having a carboxyl group in the molecule and epichlorohydrin, and alicyclic epoxy resins obtained by oxidizing compounds having double bonds in the molecule, or these Epoxy resins, in which two or more types of groups selected from the above are mixed in the molecule, have a small decrease in the elastic coefficient of the cured product even at high temperature and high humidity, and are excellent in physical properties at high temperature and high humidity when used as a composite material. Therefore, it is preferably used.

Specific examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin obtained by the reaction of bisphenol A and epichlorohydrin, bisphenol F type epoxy resin obtained by the reaction of bisphenol F and epichlorohydrin, and bisphenol AD. By the reaction of bisphenol AD type epoxy resin obtained by the reaction of epichlorohydrin, resorsinol type epoxy resin obtained by the reaction of resorcinol and epichlorohydrin, and the reaction product of phenol and formaldehyde, phenol novolac and epichlorohydrin. Examples thereof include the obtained phenol novolac type epoxy resin, other polyethylene glycol type epoxy resin, polypropylene glycol type epoxy resin, naphthalene type epoxy resin, and substituents thereof with position isomers, alkyl groups and halogens.

Bisphenol A type epoxy resins include "jER" (registered trademark) 827, "jER" (registered trademark) 828 (all manufactured by Mitsubishi Chemical Corporation), "Epicron" (registered trademark) 840, and "Epicron" (registered). Specifically, 850 (trademark) 850 (above, manufactured by DIC Corporation), "Epototo" (registered trademark) YD-128 (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.), DER-331, DER-332 (manufactured by Olin), etc. can give.

Examples of the bisphenol F type epoxy resin include "jER" (registered trademark) 806, "jER" (registered trademark) 807, "jER" (registered trademark) 1750 (all manufactured by Mitsubishi Chemical Corporation), and "Epicron" (registered). Trademark) 830, "Epicron" (registered trademark) 835 (all manufactured by DIC Co., Ltd.), "Epototo" (registered trademark) YD-170, "Epototo" (registered trademark) YD-175 (Nippon Steel & Sumitomo Metal Chemical Co., Ltd.) (Made) etc. can be specifically mentioned.

Specific examples of the bisphenol AD type epoxy resin include "EPOMIK" (registered trademark) R710 and "EPOMIK" (registered trademark) R1710 (all manufactured by Printec Co., Ltd.).

Examples of the resorcinol type epoxy resin include "Denacol" (registered trademark) EX-201 (manufactured by Nagase ChemteX Corporation).

Phenol novolac type epoxy resins include "jER" (registered trademark) 152, "jER" (registered trademark) 154 (all manufactured by Mitsubishi Chemical Corporation), and "Epicron" (registered trademark) 740 (manufactured by DIC Corporation). ) And so on.

Examples of the glycidylamine type epoxy resin include tetraglycidyldiaminodiphenylmethanes, glycidyl compounds of aminophenol, glycidylanilines, and glycidyl compounds of xylene diamine.

Examples of tetraglycidyldiaminodiphenylmethanes include "Sumiepoxy" (registered trademark) ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), "Araldite" (registered trademark) MY720, "Araldite" (registered trademark) MY721, and "Araldite" (registered trademark). MY9512, "Araldite" (registered trademark) MY9612, "Araldite" (registered trademark) MY9634, "Araldite" (registered trademark) MY9663 (manufactured by Huntsman Advanced Materials), "jER" (registered trademark) 604 (Mitsubishi) (Made by Chemical Co., Ltd.) is specifically mentioned.

Examples of aminophenol glycidyl compounds include "jER" (registered trademark) 630 (manufactured by Mitsubishi Chemical Corporation), "Araldite" (registered trademark) MY0500, and "Araldite" (registered trademark) MY0510 (Huntsman Advanced Materials). Mitsubishi Chemical Corporation), "Sumiepoxy" (registered trademark) ELM120, and "Sumiepoxy" (registered trademark) ELM100 (all manufactured by Sumitomo Chemical Corporation).

Specific examples of glycidyl anilines include GAN and GOT (all manufactured by Nippon Kayaku Co., Ltd.). Examples of the glycidyl compound of xylene diamine include TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.).

(2-2) [C] Thermoplastic Resin Particles The matrix resin composition of the present invention is a matrix resin composition containing [C] thermoplastic resin particles. The [C] thermoplastic resin particles are preferably in a fiber-reinforced composite material in which the matrix resin composition is cured, and the [C] thermoplastic resin particles maintain the particle shape. Therefore, the [C] thermoplastic resin particles are , It is preferable that the particles are made of a thermoplastic resin that is insoluble in the epoxy resin. In the present invention, the epoxy resin-insoluble thermoplastic resin refers to a thermoplastic resin in which all or at least a part of the epoxy resin remains undissolved at a temperature at which FRP is molded or lower. That is, when 10 parts by mass of a thermoplastic resin having an average particle diameter of 20 to 50 μm was mixed with 100 parts by mass of an epoxy resin and stirred at 190 ° C. for 1 hour, all or at least a part of the particles did not dissolve. A thermoplastic resin that remains and preferably has a particle size that does not change by 10% or more. Generally, the temperature for molding FRP is 100 to 190 ° C. The particle size is visually measured by a microscope, and the average particle size means the average value of the particle size of 100 randomly selected particles.

The epoxy resin-insoluble thermoplastic resin particles are in a state of being dispersed in the matrix resin of the fiber-reinforced composite material after curing (hereinafter, these dispersed particles are also referred to as "interlayer particles"). The interlayer particles suppress the propagation of the impact received by the FRP. As a result, the impact resistance of the obtained FRP is improved.

Examples of the epoxy resin-insoluble thermoplastic resin include polyamide, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyester, polyamideimide, polyimide, polyetherketone, polyetheretherketone, polyethylenenaphthalate, polyethernitrile, and polybenzimidazole. .. Among these, polyamide, polyamideimide, and polyimide are preferable because they have high toughness and heat resistance. Polyamide and polyimide are particularly excellent in the effect of improving toughness on FRP. These may be used alone or in combination of two or more. Moreover, these copolymers can also be used.

Above all, by using amorphous polyimide or polyamide, the heat resistance of the obtained FRP can be particularly improved. In particular, polyamide resin particles are preferably used as the thermoplastic resin particles, and the impact resistance can be greatly improved due to their excellent toughness. Examples of the polyamide resin particles include polyamide 12, polyamide 11, polyamide 6, polyamide 66 and polyamide 6/12 copolymer, and the epoxy compound described in Example 1 of JP-A-1-104624. Polyamide (semi-IPN polyamide) having a network structure) or the like can be preferably used. Commercially available products of polyamide particles include SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80 (all manufactured by Toray Industries, Inc.), "Organsol (registered trademark)" 1002D. , 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D, (above, manufactured by Alchema Co., Ltd.), "Grillamide (registered trademark)" TR90, TR55 (above, manufactured by Ems-Chemie), "TROGAMID (registered trademark)" CX7323, CX9701, CX9704, (all manufactured by Evonik Industries, Ltd.) and the like can be used. These polyamide particles may be used alone or in combination of two or more.

The content of the thermoplastic resin particles in the matrix resin composition is appropriately adjusted according to the viscosity of the epoxy resin composition. From the viewpoint of processability, the amount is preferably 5 to 50 parts by mass, more preferably 10 to 45 parts by mass, and 20 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition. It is more preferably a part. If it is less than 5 parts by mass, the impact resistance of the obtained FRP may be insufficient. If it exceeds 50 parts by mass, the impregnation property of the epoxy resin composition and the drape property of the obtained prepreg may be deteriorated.

The average particle size of the thermoplastic resin particles is preferably 1 to 50 μm, particularly preferably 3 to 30 μm, from the viewpoint of the handleability of the matrix resin composition and the physical properties of the fiber-reinforced composite material. If the particle size is too small, the viscosity of the epoxy resin composition may increase significantly. If the particle size is too large, it may be difficult to obtain a sheet having a uniform thickness when the epoxy resin composition is processed into a sheet.

(2-3) [D] Inorganic Additive The matrix resin composition of the present invention is a matrix resin composition containing an inorganic filler having a [D] Mohs hardness of 6 or more. The Mohs hardness referred to in the present invention is the Mohs hardness with diamond as 10. Examples of inorganic additives having a Mohs hardness of 6 or more include aluminum borate (Mohs hardness 7 to 7.5), alumina (Mohs hardness 9), silicon carbonate (Mohs hardness 9), and silicon nitride (Mohs hardness 9). Various silicate minerals can be mentioned. In particular, it is preferable to use a silicate mineral because of its availability. Examples of commercially available silicate minerals include THIXOTOPIC AGENT DT 5039 (manufactured by Huntsman Japan Corporation, magnesium silicate).

The content of the inorganic additive in the matrix resin composition is appropriately adjusted according to the viscosity of the epoxy resin composition. From the viewpoint of processability, the amount is preferably 0.0001 to 5 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the epoxy resin contained in the epoxy resin composition. It is more preferably 0.3 to 7 parts by mass. If the amount added is too small, the impact resistance of the obtained FRP may be insufficient. If the amount added is too large, the impregnation property of the epoxy resin composition and the drape property of the obtained prepreg may be deteriorated.

The average particle size of the inorganic additive is preferably 1 to 50 μm, particularly preferably 3 to 30 μm, from the viewpoint of handleability of the matrix resin composition and the physical properties of the fiber-reinforced composite material. If the particle size is too small, the viscosity of the epoxy resin composition may increase significantly. If the particle size is too large, it may be difficult to obtain a sheet having a uniform thickness when the epoxy resin composition is processed into a sheet.

(2-4) [E] Curing Agent The matrix resin composition of the present invention may contain a curing agent, if necessary. The curing agent is not particularly limited as long as it is a curing agent that cures the epoxy resin, and for example, aromatic amines, aliphatic amines, polyamide amines, carboxylic acid anhydrides, Lewis acid complexes, acid-based curing catalysts, and bases. A system curing catalyst and the like can be mentioned. Of these, aliphatic amines are preferably used from the viewpoint of reactivity, and aromatic amines are preferably used from the viewpoint of the physical properties of the obtained cured product.

Examples of the aromatic amine include diaminodiphenylsulfone and diaminodiphenylmethane, and more specifically, SEIKACURE-S (manufactured by Wakayama Seika Kogyo Co., Ltd., 4,4'-diaminodiphenylsulfone), 3,3'. -DAS (Mitsui Kagaku Fine Co., Ltd., 3,3'-diaminodiphenyl sulfone), "Ancamine" (registered trademark) 2049 (Aromatic polyamine manufactured by Air Products Japan Co., Ltd.), and the like can be mentioned.

In the present invention, the aromatic polyamine is a curing agent composed of an aromatic polyamine having at least one aliphatic substituent, an aromatic substituent, or a substituent of a halogen atom at the ortho position with respect to the amino group. It is more preferable from the viewpoint of storage stability and moisture resistance and heat resistance. Examples of such aromatic polyamines include 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane and 4,4'-diamino-3,3'-diethyl-5,5'-. Didimethyldiphenylmethane, 4,4'-diamino-3,3'5,5'5,5'-tetraethyldiphenylmethane, 3,3'-dichloro-2,2', 6,6'-tetraethyl-4,4'- Examples include methylene dianiline. More specifically, "Lonzacure M-MIPA" (registered trademark) (4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane manufactured by Lonza), "MED-J" (registered). Trademark) (4,4'-diamino-3,3'-dichloro-5,5'-dimethyldiphenylmethane manufactured by Kumiai Chemical Co., Ltd.), "Lonzacure M-DEA" (registered trademark) (4,4'-diamino manufactured by Lonza Co., Ltd.) -3,3'5,5'5,5'-tetraethyldiphenylmethane), "Lonzacure M-CDEA" (registered trademark) (Lonza 3,3'-dichloro-2,2', 6,6'-tetraethyl -4,4'-methylenedianiline) and the like.

Examples of aliphatic amines include diethylenetriamine, triethylenetetramine, dicyandiamide, tetraethylenepentamine, diproprenedamine, piperidine, N, N-dimethylpiperazine, triethylenediamine, polyamideamine, octylamine, laurylamine, myristylamine, and stearyl. Examples include amines, cocoalkylamines, beef alkylamines, oleylamines, hardened beef alkylamines, N, N-dimethyllaurylamines, and N, N-dimethylmyristylamines. More specifically, DICY7 (dicyandiamide manufactured by Japan Epoxy Resin Co., Ltd.) and the like can be mentioned.

More specifically, as the polyamide amine, "Tohmide" (registered trademark) 235S, "Tohmide" (registered trademark) 296, and "Tohmide" (registered trademark) 2400 (all manufactured by Fuji Kasei Kogyo Co., Ltd.) are used. Can be mentioned.

Further, it is preferable to use these curing agents in combination with a curing accelerator (curing aid) in order to enhance the curing activity. Preferred examples of combining an epoxy resin with a curing aid include dicyandiamide combined with a urea derivative such as 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU) as a curing aid, and aromaticity. Examples thereof include a combination of a boron trifluoride ethylamine complex as a curing aid with a group amine, and an example of combining a tertiary amine with a carboxylic acid anhydride or a novolak resin as a curing aid.

In the present invention, it is particularly preferable that the curing agent is any one or a combination of dicyandiamide, urea-based curing accelerator and aromatic amine, from the viewpoint of moldability and mechanical properties of the obtained composite material. The amount of the curing agent added to the thermosetting resin is preferably adjusted based on the stoichiometric ratio with respect to the thermosetting resin from the viewpoint of heat resistance and reactivity. When a curing aid is used, the amount is preferably 0.001 to 1 equivalent with respect to the functional group of the thermosetting resin.

(2-5) Epoxy Resin-soluble Thermoplastic Resin The epoxy resin composition of the present invention preferably further contains an epoxy resin-soluble thermoplastic resin. The epoxy resin-soluble thermoplastic resin adjusts the viscosity of the epoxy resin composition and improves the impact resistance of the obtained FRP.

In the present invention, the epoxy resin-soluble thermoplastic resin refers to a thermoplastic resin that can be completely dissolved in the epoxy resin by heating or the like. Here, the fact that a part of the epoxy resin is dissolved means that when 10 parts by mass of a thermoplastic resin having an average particle diameter of 20 to 50 μm is mixed with 100 parts by mass of the epoxy resin and stirred at 190 ° C. for 1 hour, the particles are dissolved. Means that disappears.

Specific examples of the epoxy resin-soluble thermoplastic resin used in combination with the epoxy resin include polysulfone, polyethersulfone, polyetherimide, polyarylate, and polycarbonate resin. These may be used alone or in combination of two or more. Among these, polysulfone and / and polyethersulfone are more preferable because the obtained FRP has particularly excellent impact resistance, fracture toughness and solvent resistance, and it is further preferable to use polysulfone.

The epoxy resin-soluble thermoplastic resin is more preferably a thermoplastic resin having a reactive group having a reactivity with the epoxy resin or a functional group forming a hydrogen bond. Such an epoxy resin-soluble thermoplastic resin is excellent in dissolution stability in the curing process of the epoxy resin. Further, toughness, chemical resistance, heat resistance and moisture heat resistance can be imparted to the FRP obtained after curing.

As the reactive group having reactivity with the epoxy resin, a hydroxyl group, a carboxylic acid group, an imino group, an amino group and the like are preferable. Among these, the use of amine-terminated or hydroxyl-terminated polysulfone or polyethersulfone is more preferable because the resulting composite material is particularly excellent in impact resistance, fracture toughness and solvent resistance.

As a commercially available product of an epoxy resin-soluble thermoplastic resin having a reactive end group to be combined with an epoxy resin, a polyether sulfone "Sumika Excel" (registered trademark) PES5003P (manufactured by Sumitomo Chemical Co., Ltd.) having a terminal reactive hydroxyl group is available. , "Virantage" (registered trademark) VW-10700RSF (manufactured by Solvay Specialty Polymers), polyether sulfone "Virantage" (registered trademark) DAMS VW-30500RP (manufactured by Solvay Specialty Polymers) having a terminal reactive hydroxyl group. ) And so on.

The thermoplastic resin used in the present invention preferably has a weight average molecular weight of 1000 to 20000. When the weight average molecular weight is in this range, sufficient toughness can be imparted to the obtained cured product. If the molecular weight is too low, it is difficult to obtain sufficient toughness. On the other hand, if the molecular weight is too high, the viscosity of the resin composition becomes too high, and processing problems such as difficulty in impregnating the reinforcing fibers with the resin composition tend to occur.

The content of the epoxy resin-soluble thermoplastic resin in the present resin composition is preferably 5 to 60 parts by mass, more preferably 10 to 50 parts by mass, and 10 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin. It is particularly preferably 40 parts by mass. When the content of the thermoplastic resin is within this range, the viscosity of the obtained resin composition does not become too high, the handleability in the resin composition manufacturing process and the prepreg manufacturing process is good, and the fiber-reinforced composite material is used. Impact resistance can be increased.

(2-6) Other Additives In addition to the above components, the epoxy resin composition of the present invention contains thickening particles, conductive particles and flame retardants, and inorganic fillers other than [D], if necessary. An internal mold release agent or the like may be blended.

The matrix resin composition may contain thickening particles. Since the thickening particles dispersed in the matrix resin swell in the resin composition by heating, it is possible to maintain an appropriate viscosity of the resin composition during heat curing and suppress the outflow of the resin during molding.

When an epoxy resin is used as the matrix resin, examples of the thickening particles include particles obtained by copolymerizing a single or a plurality of unsaturated compounds with a crosslinkable monomer. Although not particularly limited, it is desirable to include a resin having at least one of an acrylic acid ester compound, a methacrylic acid ester compound, and a vinyl compound as a monomer unit.

The thickening particles preferably have an average degree of polymerization of 4,000 to 40,000. As the thickening particles, it is also preferable to use commercially available products made of an alkyl methacrylate polymer having no core-shell structure, such as Zephyac F325 and Zephyac F320 (both are Aica Kogyo Co., Ltd.).

The particle size of the thickening particles is not particularly limited, but the average particle size is preferably 0.3 to 10 μm, and more preferably 0.5 to 8 μm. The content of the thickening particles is preferably 2 to 20 parts by mass, more preferably 3 to 18 parts by mass, and particularly preferably 4 to 15 parts by mass with respect to 100 parts by mass of the epoxy resin. ..

The conductive particles include conductive polymer particles such as polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaften particles and polyethylenedioxythiophene particles, carbon particles, carbon fiber particles, metal particles, inorganic materials or organic particles. Examples thereof include particles in which a core material made of a material is coated with a conductive substance.

Examples of the flame retardant include phosphorus-based flame retardants. The phosphorus-based flame retardant is not particularly limited as long as it contains a phosphorus atom in the molecule, and examples thereof include organic phosphorus compounds such as phosphoric acid ester, condensed phosphoric acid ester, phosphazene compound, and polyphosphate, and red phosphorus. Be done.

The inorganic additives other than [D] are inorganic additives having a Mohs hardness of less than 6, such as calcium carbonate (Mohs hardness 3.5-4), potassium titanate (Mohs hardness 3.5), and magnesium sulfate (Mohs hardness 3.5). Mohs hardness 3), zinc oxide (Mohs hardness 4-5), graphite (Mohs hardness 1-2), calcium sulfate (Mohs hardness 3), magnesium borate (Mohs hardness 5.5), magnesium oxide (Mohs hardness 5) Can be mentioned.

Examples of the internal mold release agent include metal soaps, vegetable waxes such as polyethylene wax and carbana wax, fatty acid ester-based mold release agents, silicon oil, animal wax, and fluorine-based nonionic surfactant. The blending amount of these internal mold release agents is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the epoxy resin. Within this range, the mold release effect from the mold is preferably exhibited.

Commercially available internal mold release agents include "MOLD WIZ (registered trademark)" INT1846 (AXEL PLASTICS RESEARCH LABORATORIES INC.), Licowax S, Licowax P, Licowax OP, Licowax PE190, Licowax PE190, Licowax PE190, Licowax Stearyl stearate (SL-900A (manufactured by Riken Vitamin Co., Ltd.)) and the like can be mentioned.

(2-7) Method for Producing Matrix Resin Composition The matrix resin composition of the present invention comprises [B] epoxy resin, [C] thermoplastic resin particles, [D] inorganic filler having a Morse hardness of 6 or more, and if necessary. [E] It can be produced by mixing a curing agent, an epoxy resin-soluble thermoplastic resin, and other components. When an epoxy resin-soluble thermoplastic resin is used, it is preferable to mix and dissolve the epoxy resin-soluble thermoplastic resin in the epoxy resin in advance using a stirrer.

The mixing method is not particularly limited, and any conventionally known method may be used. The mixing temperature can be exemplified in the range of 80 to 120 ° C. If the mixing temperature is too high, the curing reaction will partially proceed to reduce the impregnation property into the reinforcing fiber base material layer, or the storage stability of the obtained epoxy resin composition and the prepreg produced using the same. May decrease. On the other hand, if the mixing temperature is too low, the dissolution in the epoxy resin composition may be insufficient, which may affect the quality during prepreg production. It is preferably in the range of 90 to 120 ° C, more preferably 100 to 120 ° C.

When [B] epoxy resin is mixed with [C] thermoplastic resin particles, [D] inorganic filler, and if necessary, [E] curing agent and other components, the mixing temperature is in the range of 40 to 90 ° C. The temperature is preferably 60 to 90 ° C, more preferably 60 to 80 ° C.

As the mixing machine device, a conventionally known one can be used. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a vanbury mixer, a mixing vessel equipped with a stirring blade, a horizontal mixing tank, and the like. The mixing of each component can be carried out in the atmosphere or in an atmosphere of an inert gas. When mixing is performed in the atmosphere, an atmosphere in which the temperature and humidity are controlled is preferable. Although not particularly limited, for example, it is preferable to mix in a temperature controlled to a constant temperature of 30 ° C. or lower or a low humidity atmosphere having a relative humidity of 50% RH or less.

(3) Fiber Reinforced Composite Material The fiber reinforced composite material of the present invention is combined with a reinforcing fiber and a matrix resin, for example, by known means and methods such as autoclave molding, press molding, resin transfer molding, filament winding molding, and injection molding. can get.

The fiber-reinforced composite material may be produced through an intermediate material such as a prepreg in which the reinforcing fibers are integrated with the matrix resin, or may be integrated when the fiber-reinforced composite material is molded.

The content of the matrix resin composition in the entire fiber-reinforced composite material is preferably 15 to 60% by mass based on the total mass of the fiber-reinforced composite material from the viewpoint of mechanical properties and handleability. If the resin content is too low, voids or the like may be generated in the fiber-reinforced composite material, and the mechanical properties may be deteriorated. If the resin content is too high, the reinforcing effect of the reinforcing fibers may be insufficient, and the mechanical properties relative to the mass may be substantially low. The resin content is preferably 20 to 55% by mass, more preferably 25 to 50% by mass.

(3-1) Method for Producing a Prepreg When a fiber-reinforced composite material is obtained via a prepreg, the method for producing a prepreg is not particularly limited, and any conventionally known method can be adopted. Specifically, the hot melt method and the solvent method can be preferably adopted.

In the hot melt method, a resin composition is applied in the form of a thin film on a release paper to form a resin composition film, and the resin composition film is laminated on a reinforcing fiber base material and heated under pressure. This is a method of impregnating the resin composition into the reinforcing fiber base material layer.

The method for forming the resin composition into a resin composition film is not particularly limited, and any conventionally known method can be used. Specifically, a resin composition film is obtained by casting and casting a resin composition on a support such as a release paper or a film using a die extrusion, an applicator, a reverse roll coater, a comma coater, or the like. Can be done. The resin temperature at the time of producing the film is appropriately determined according to the composition and viscosity of the resin composition. Specifically, the same temperature conditions as the mixing temperature in the method for producing the epoxy resin composition described above are preferably used. The resin composition may be impregnated into the reinforcing fiber base material layer once or divided into a plurality of times.

The solvent method is a method in which a resin composition is formed into a varnish using an appropriate solvent, and the varnish is impregnated in the reinforcing fiber base material layer.

Among these conventional methods, it can be preferably produced by a hot melt method that does not use a solvent.

When an epoxy resin is used as the matrix resin, the impregnation temperature when the resin composition film is impregnated into the reinforcing fiber base material layer by a hot melt method is preferably in the range of 50 to 140 ° C. If the impregnation temperature is too low, the viscosity of the epoxy resin may be high and the reinforcing fiber base material layer may not be sufficiently impregnated. If the impregnation temperature is too high, the curing reaction of the epoxy resin composition may proceed, and the storage stability of the obtained prepreg may decrease or the drape property may decrease. The impregnation temperature is more preferably 60 to 135 ° C., particularly preferably 70 to 130 ° C.

The impregnation pressure when the epoxy resin composition film is impregnated into the reinforcing fiber base material layer by the hot melt method is appropriately determined in consideration of the viscosity and resin flow of the resin composition. The specific impregnation pressure is 1 to 50 (kN / cm), preferably 2 to 30 (kN / cm).

(3-2) Method for Producing Fiber Reinforced Composite Material A fiber reinforced composite material can be obtained by molding and curing the above prepreg. Examples of the method for producing the fiber-reinforced composite material using the prepreg include known molding methods such as autoclave molding and press molding.

As a method for producing a fiber-reinforced composite material from a prepreg, an autoclave molding method is preferably used. In the autoclave molding method, a prepreg and a film bag are sequentially laid on the lower mold of the mold, the prepreg is sealed between the lower mold and the film bag, and the space formed by the lower mold and the film bag is evacuated. , It is a molding method that heats and pressurizes with an autoclave molding apparatus. The molding conditions are preferably such that the heating rate is 1 to 50 ° C./min, and heating and pressurization are performed at 0.2 to 0.7 MPa and 130 to 180 ° C. for 10 to 150 minutes.

Further, as a method for producing a fiber-reinforced composite material using a prepreg, a press molding method is also preferably used. The fiber-reinforced composite material produced by the press molding method is produced by heating and pressurizing a prepreg or a preform formed by laminating prepregs using a mold. The mold is preferably preheated to a curing temperature.

The temperature of the mold during press molding is preferably 150 to 210 ° C. When the molding temperature is 150 ° C. or higher, a sufficient curing reaction can be caused, and a fiber-reinforced composite material can be obtained with high productivity. Further, when the molding temperature is 210 ° C. or lower, the resin viscosity does not become too low, and excessive flow of the resin in the mold can be suppressed. As a result, the outflow of resin from the mold and the meandering of fibers can be suppressed, so that a high-quality fiber-reinforced composite material can be obtained.

The pressure at the time of molding is 0.05 to 2 MPa. When the pressure is 0.05 MPa or more, an appropriate flow of the resin can be obtained, and it is possible to prevent poor appearance and generation of voids. In addition, since the prepreg is sufficiently adhered to the mold, a fiber-reinforced composite material having a good appearance can be produced. When the pressure is 2 MPa or less, the resin does not flow more than necessary, so that the appearance of the obtained fiber-reinforced composite material is unlikely to deteriorate. Further, since the mold is not loaded more than necessary, the mold is unlikely to be deformed. The molding time is preferably 0.5 to 8 hours.

In the fiber-reinforced composite material of the present invention, after integrating the reinforcing fibers and the uncured matrix resin composition, the matrix resin is cured by heating at a pressure of 0.1 to 2 MPa and a temperature of 150 to 210 ° C. for 1 to 8 hours. It is particularly preferable from the viewpoint of the mechanical properties of the fiber-reinforced composite material.

The fiber-reinforced composite material of the present invention uses a molding method such as resin transfer molding, resin film infusion molding, or filament winding molding in addition to the method via a prepreg as described above, to reinforce the fiber in the molding die or in the molding process. May be impregnated with a matrix resin.

Since the fiber-reinforced composite material of the present invention thus obtained has excellent toughness and impact resistance, it can be preferably used in a wide range of fields such as aircraft, automobiles, sports / leisure, and general industry.

Carbon fibers were produced under the conditions described in the following Examples and Comparative Examples. Various physical property values of each carbon fiber were measured by the following methods.

<[A] Reinforcing fiber>
-Carbon fiber 1: Carbon fiber obtained in Production Example 1, strand tensile strength 5200 MPa, strand tensile elastic modulus 277 GPa, single fiber system 6.8 μm
-Carbon fiber 2: The carbon fiber obtained in Production Example 1, the strand tensile strength 6000 MPa, the strand tensile elastic modulus 290 GPa, the single fiber system 4.8 μm.

(Manufacturing Example 1)
As the precursor fiber, a polyacrylonitrile fiber (total fineness 3067tex) having a single fiber fineness of 1.2 dtex, a single fiber diameter of 11.7 μm, and a filament number of 24,000 was used. The precursor fiber was subjected to a flame-resistant treatment at 240 ° C. in air until the fiber density reached 1.35 g / cm ³ , to obtain a flame-resistant fiber.

Next, the first carbonization treatment is performed in a first carbonization furnace having a maximum temperature of 640 ° C. under a nitrogen gas atmosphere, and further, in a second carbonization furnace having an inlet temperature of 600 ° C. and a maximum temperature of 1580 ° C. under a nitrogen atmosphere, the first carbonization treatment is performed. A dicarbonation treatment was carried out to obtain carbon fibers having a single fiber diameter of 6.8 μm.

The obtained carbon fibers were surface-treated by electrolytic oxidation at an electric amount of 20 C / g in an aqueous solution of ammonium sulfate, and then sized with an epoxy resin. Strand tensile strength 5200 MPa, strand tensile modulus 277 GPa, single fiber system A 6.8 μm carbon fiber was obtained.

(Manufacturing Example 2)
The same polyacrylonitrile fiber (total fineness 1707tex) as in Production Example 1 was used except that the single fiber diameter was changed to 8.8 μm. A carbon fiber having a strand tensile strength of 6000 MPa, a strand tensile elastic modulus of 290 GPa, and a single fiber system of 4.8 μm was obtained in the same manner as in Production Example 1 except that the maximum temperature of the second carbonization furnace was set to 1470 ° C.

<Resin composition>
〔component〕
[B] Epoxy resin / TGDDM: Tetraglycidyl-4,4'-diaminodiphenylmethane, Huntsman Corporation Araldite MY721 (product name)
-DGEBA: Bisphenol A-diglycidyl ether, jER825 manufactured by Mitsubishi Chemical Corporation (product name)
-TG-mAP: Triglycidyl-m-aminophenol, Huntsman Corporation Araldite MY0600 (product name)
-3,4'-TGDDE: Tetraglycidyl-3,4'-diaminodiphenyl ether (synthesized by the following method)
-Resorcinol-DG: Resorcinol diglycidyl ether, EX-201 (product name) manufactured by Nagase ChemteX Corporation.

(Synthesis of 3,4'-TGDDE)
A four-necked flask equipped with a thermometer, a dropping funnel, a condenser and a stirrer was charged with 1146.2 g (12.0 mol) of epichlorohydrin, and the temperature was raised to 70 ° C. while purging with nitrogen, and ethanol was added thereto. 200.2 g (1.0 mol) of 3,4'-diaminodiphenyl ether dissolved in 1000 g was added dropwise over 4 hours. The mixture was further stirred for 6 hours to complete the addition reaction to give N, N, N', N'-tetrakis (2-hydroxy-3-chloropropyl) -3,4'-diaminodiphenyl ether. Subsequently, the temperature inside the flask was lowered to 25 ° C., and then 480.0 g (6.0 mol) of a 48% NaOH aqueous solution was added dropwise to the flask over 2 hours, and the mixture was further stirred for 1 hour. After the cyclization reaction was completed, ethanol was distilled off, extraction was performed with 400 g of toluene, and the mixture was washed twice with 5% saline solution. When toluene and epichlorohydrin were removed from the organic layer under reduced pressure, 361.7 g (yield 85.2%) of a brown viscous liquid was obtained. The purity of the main product, 3,4'-TGDDE, was 84% (HPLC area%).

[C] Epoxy resin insoluble thermoplastic resin particles PA12: Polyamide 12 resin particles (VESTSINT2158, average particle diameter 20 μm, manufactured by Daicel Ebonic Co., Ltd.)
PA1010: Polyamide 1010 resin particles (VESTSINT9158, average particle size 20 μm, manufactured by Daicel Ebonic Co., Ltd.)

[D] Inorganic additive DT5039: Magnesium silicate, manufactured by Huntsman Japan Co., Ltd. THIXOTOPIC AGENT DT 5039 (product name)
[E] Hardener, 4,4'-DDS: Aromatic amine-based hardener, 4,4'-diaminodiphenyl sulfone, Seika Cure S (trade name) manufactured by Wakayama Seika Kogyo Co., Ltd.
・ 3,3'-DDS: Aromatic amine-based curing agent, 3,3'-diaminodiphenyl sulfone, manufactured by Konishi Chemical Industry Co., Ltd.

(Other ingredients)
[Thermoplastic resin]
-PES: Polyester sulfone (epoxy resin-soluble thermoplastic resin), PES-5003P (trade name) manufactured by Sumitomo Chemical Co., Ltd., average particle size 20 μm

<Evaluation method>
(Tackiness of prepreg)
The tackiness of the prepreg was measured by the following method using a tacking test device TAC-II (RHESCA CO., LTD.). As a test method, when a prepreg is set on a test stage held at 27 ° C, a load of 0.98 N is applied with a φ5 tack probe held at 27 ° C, and the prepreg is pulled out at a test speed of 10 mm / sec. The maximum load of was calculated.

A tack probe test was carried out on the prepreg immediately after production and the prepreg stored at a temperature of 26.7 ° C. and a humidity of 65% for 10 days. The evaluation results are represented by the following criteria (○ to ×).
◯: The load immediately after production is 1.96 N or more and the tack retention rate after storage for 10 days is 50% or more and less than 100% ×: The load immediately after production is 1.96 N or more and the tack retention rate after storage for 10 days is Less than 50%

(Resin flow)
The prepreg was cut to a size of 150 mm × 150 mm to obtain a preform laminated in two layers of [0 ° / 90 °] / [90 ° / 0 °]. The upper and lower molds of the press are preheated to 150 ° C., the preform is placed on the lower mold, the upper mold is immediately lowered, the press is closed, and the press is held at 0.1 MPa for 30 seconds, and then 2 MPa. Pressure was applied to heat and pressurize for 5 minutes to cure, and after curing, the product was taken out from the press to obtain a molded product. The resin burrs that flowed out to the end of the molded product were removed, the mass before and after molding was measured, and the resin flow amount (%) of the prepreg was calculated.
W1; Mass of preform before molding (g)
W2; Mass (g) of the molded product (after deburring of the resin) after molding
Resin flow amount (%) of prepreg = (W1-W2) / W1 × 100

(Resin layer thickness)
The unidirectional prepreg was cut into a square having a side of 360 mm and laminated to obtain a laminated body having _{a laminated structure [+ 45/0 / -45/90] 3S.} Using a normal vacuum autoclave molding method, molding was performed under a pressure of 0.59 MPa at 180 ° C. for 2 hours. The obtained molded product was cut to a size of 101.6 mm in width × 152.4 mm in length to obtain a test piece. The cross section (thickness direction) of the obtained test piece was observed at 20 times with a Scanning Laser Microscope manufactured by Laser Co., Ltd., and the thickness of the resin layer of the composite material was read. Here, the thickness of the resin layer is defined as the thickness of the layer made of only the resin containing no carbon fiber and between the resin impregnated layer made of the carbon fiber and the resin.

(Compressive strength after impact (CAI))
The unidirectional prepreg was cut into a square having a side of 360 mm and laminated to obtain a laminated body having _{a laminated structure [+ 45/0 / -45/90] 3S.} Using a normal vacuum autoclave molding method, molding was performed under a pressure of 0.59 MPa at 180 ° C. for 2 hours. The obtained molded product was cut to a size of 101.6 mm in width × 152.4 mm in length to obtain a test piece for a post-impact compressive strength (CAI) test. After measuring the dimensions of each test piece, the test piece (sample) was subjected to an impact energy of 30.5 J using a drop weight type impact tester (Dynataup manufactured by Instron). After the impact, the damaged area of the specimen was measured with an ultrasonic flaw detection tester (SDS3600, HIS3 / HF manufactured by Clout Kramer). After the impact, the strength test of the specimen was performed by attaching one strain gauge to each of the left and right at a position 25.4 mm from the top of the specimen and 25.4 mm from the side, and similarly, a total of four strains / body strain was attached to the front and back. After attaching the gauge, the crosshead speed of the testing machine (autograph manufactured by Shimadzu Corporation) was set to 1.27 mm / min, and the load was applied until the specimen broke.

(Interlayer fracture toughness mode I (GIc))
The unidirectional prepreg was cut into a square having a side of 360 mm and then laminated to prepare two laminated bodies in which 10 layers were laminated in the 0 ° direction. In order to generate initial cracks, a release sheet was sandwiched between two laminated bodies, and both were combined to obtain a prepreg laminated body having _{a laminated structure [0] 20.} Using a normal vacuum autoclave molding method, molding was performed under a pressure of 0.59 MPa at 180 ° C. for 2 hours. The obtained molded product (fiber-reinforced composite material) was cut to a size of 12.7 mm in width × 304.8 mm in length to obtain a test piece of interlayer fracture toughness mode I (GIc).

As a GIc test method, a double cantilever beam interlayer fracture toughness test method (DCB method) is used to generate a pre-crack (initial crack) of 12.7 mm from the tip of the release sheet, and then further develop the crack. Was done. The test was terminated when the crack growth length reached 127 mm from the tip of the pre-crack. The crosshead speed of the test piece tensile tester was 12.7 mm / min, and the measurement was performed at n = 5.

The crack growth length was measured from both end faces of the test piece using a microscope, and the GIc was calculated by the integral method by measuring the load and the crack opening displacement.

[Examples 1 to 5]
A fiber-reinforced composite material was prepared by using an epoxy resin composition obtained by mixing the above resins at the ratios shown in Table 1 and the carbon fibers shown in Table 1.

At the ratios shown in Table 1, the polyether sulfone was stirred at 120 ° C. for 60 minutes using a planetary mixer in the epoxy resin, and the polyether sulfone was completely dissolved in the epoxy resin. Then, the temperature was lowered to 80 ° C., a curing agent and epoxy resin insoluble thermoplastic resin particles were added and mixed for 30 minutes to prepare an epoxy resin composition.

Using a reverse roll coater, the obtained epoxy resin composition was applied onto a release paper to ^{prepare two} 50 g / m 2 resin films. Next, a sheet-shaped fiber-reinforced base material layer was prepared by arranging carbon fibers in one direction so that the fiber mass per unit area was 190 g / m ^2. A resin film is stacked on both sides of this fiber-reinforced base material layer, and heated and pressed under the conditions of an impregnation temperature of 130 ° C. and a pressure of 0.5 MPa to obtain an uncured fiber-reinforced composite material having a carbon fiber content of 65% by mass. Made.

The tackiness, resin flow, resin thickness, CAI, and interlaminar fracture toughness (GIc) of the uncured fiber-reinforced composite material obtained in Examples 1 to 5 were evaluated. The fiber-reinforced composite materials of Examples 1 to 5 were all excellent in tackiness and the resin flow was sufficiently suppressed. In addition, all of the examples had sufficiently excellent impact resistance and interlayer fracture toughness.

[Comparative Example 1]
A prepreg was prepared with [D] / [C] set to 0 without adding inorganic particles. A fiber-reinforced composite material was produced in the same manner as in Example 1 except that the proportion of the epoxy resin composition was changed to the proportion shown in Table 1. The fiber-reinforced composite material obtained in Comparative Example 1 had a low resin viscosity and a high resin flow because no inorganic particles were added. Therefore, the thickness of the resin layer is insufficient, and the interlaminar fracture toughness is low, which is insufficient.

[Comparative Example 2]
A prepreg was prepared with [D] / [C] set to 0.64. A prepreg was prepared in the same manner as in Example 1 except that the proportion of the epoxy resin composition was changed to the proportion shown in Table 1. The prepreg obtained in Comparative Example 2 in which [D] / [C] was too large was a prepreg having insufficient tackiness and poor handleability. In addition, the CAI was low and the impact resistance was insufficient.

Claims (5)

[A] A fiber-reinforced composite material obtained by impregnating a fiber layer made of reinforcing fibers with a matrix resin composition.
The matrix resin composition is a matrix resin composition composed of at least [B] epoxy resin, [C] thermoplastic resin particles, and [D] an inorganic additive having a Mohs hardness of 6 or more, and satisfies the formula (1). A fiber-reinforced composite material characterized by being a resin composition.
0 <Mixing amount of matrix resin composition of [D] / Mixing amount of matrix resin composition of [C] <0.6 ... Equation (1) [B] The fiber-reinforced composite material according to claim 1, wherein the epoxy resin is an epoxy resin having at least bifunctional or higher functional epoxy groups. [C] The fiber-reinforced composite material according to claim 1 or 2, wherein the thermoplastic resin particles are polyamide particles. The fiber-reinforced composite material according to any one of claims 1 to 3, wherein the content of the inorganic additive is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin [A]. [A] A method for producing a fiber-reinforced composite material in which a fiber layer made of reinforcing fibers is impregnated with a matrix resin composition.
The matrix resin composition is a matrix resin composition composed of at least [B] epoxy resin, [C] thermoplastic resin particles, and [D] an inorganic additive having a Morse hardness of 6 or more, and satisfies the formula (1). A method for producing a fiber-reinforced composite material, which is a resin composition.
0 <Mixing amount of matrix resin composition of [D] / Mixing amount of matrix resin composition of [C] <0.6 ... Equation (1)