JP2021195473A - Prepreg - Google Patents

Abstract

To provide a prepreg which has excellent tackiness as a prepreg, and enables production of a fiber-reinforced composite material having excellent compression characteristics and interlaminar toughness.SOLUTION: A prepreg is composed of a reinforcement fiber base material, a primary prepreg composed of an epoxy resin composition A impregnated in a reinforcement fiber layer formed of the reinforcement fiber base materials, and a surface layer which is formed on one surface or both surfaces of the primary prepreg and is composed of an epoxy resin composition B, in which the epoxy resin composition A and the epoxy resin composition B are blended in the following manner. Epoxy resin composition A: containing an epoxy resin having an epoxy equivalent of 120 g/eq or less and a curing agent of the epoxy resin, and having a content of the curing agent to the total amount of the epoxy resin contained in the epoxy resin composition A of 150-300% in an equivalent ratio. Epoxy resin composition B: containing an epoxy resin represented by the following chemical formula (1).SELECTED DRAWING: None

Description

The present invention relates to a prepreg used for producing a fiber reinforced composite material.

Fiber-reinforced composite materials consisting of reinforced fibers and resins (hereinafter sometimes referred to as "composites") are widely applied to aircraft, sports / leisure, and general industries due to their features such as light weight, high strength, and high elastic modulus. .. This fiber-reinforced composite material is often manufactured via a prepreg in which a reinforcing fiber and a resin are integrated in advance.

A thermosetting resin or a thermoplastic resin is used as the resin constituting the prepreg. In particular, prepregs using thermosetting resins are widely used because of their high degree of molding freedom due to their tackiness and drapeability. However, since thermosetting resins generally have low toughness, if a thermosetting resin is used as the resin constituting the prepreg, there is a problem that the impact resistance of the composite produced by using the thermosetting resin is lowered. Therefore, many methods for improving impact resistance have been studied.
As a method for improving impact resistance, for example, the methods described in Patent Documents 1 to 5 have been conventionally known.

Patent Document 1 describes a method of imparting toughness to a thermosetting resin by dissolving the thermoplastic resin in the thermosetting resin. According to this method, a certain degree of toughness can be imparted to the thermosetting resin. However, in order to impart high toughness, a large amount of thermoplastic resin must be dissolved in the thermosetting resin. As a result, the thermosetting resin in which a large amount of thermoplastic resin is dissolved has a remarkably high viscosity, and it becomes difficult to impregnate a sufficient amount of resin into the inside of the reinforcing fiber base material made of carbon fiber. Composites made using such prepregs contain defects such as voids. As a result, it has a negative effect on the compression performance and damage tolerance of the composite structure.

Patent Documents 2 to 4 describe a prepreg in which thermoplastic resin fine particles are localized on the surface of the prepreg. Since these prepregs have a particle-shaped thermoplastic resin localized on the surface, the initial tackiness is low. In addition, since the curing reaction with the curing agent inherent in the surface layer proceeds, the storage stability is poor, and the tackiness and drape property deteriorate with time. Further, the composite produced by using the prepreg in which the curing reaction has progressed has many defects such as voids, and the mechanical properties of the composite structure are significantly deteriorated.

Patent Document 5 describes a prepreg in which particles, fibers or films of a thermoplastic resin are distributed in the vicinity of the surface layer on one side or both sides. When particles or fibers are used as the thermoplastic resin, the tackiness is low or the mechanical properties of the obtained composite are lowered for the same reason as in Patent Documents 2 to 4 described above. Further, when a film is used as the thermoplastic resin, the tackiness and drape property which are advantages of the thermosetting resin are lost. In addition, the drawbacks derived from the thermoplastic resin, such as poor solvent resistance, are significantly reflected in the composite structure.

Japanese Unexamined Patent Publication No. 60-243113 Japanese Unexamined Patent Publication No. 07-41575 Japanese Unexamined Patent Publication No. 07-415676 Japanese Unexamined Patent Publication No. 07-41577 Japanese Unexamined Patent Publication No. 08-259713

An object of the present invention is to provide a prepreg capable of producing a fiber-reinforced composite material having excellent tackiness as a prepreg and also having excellent compression characteristics and interlayer toughness.

That is, the present invention forms a primary prepreg composed of a reinforcing fiber base material and an epoxy resin composition A impregnated in the reinforcing fiber layer formed by the reinforcing fiber base material, and one or both sides of the primary prepreg. It is a prepreg composed of a surface layer made of the epoxy resin composition B and the epoxy resin composition B, each of which has the following composition.
Epoxy resin composition A:
An epoxy containing an epoxy resin having an epoxy equivalent of 120 g / eq or less and a curing agent for the epoxy resin, and the content of the curing agent is 150 to 300% as an equivalent ratio to the total amount of the epoxy resin contained in the epoxy resin composition A. Resin composition Epoxy resin composition B:
An epoxy resin composition containing an epoxy resin represented by the following chemical formula (1).

(However, in Chemical _{formula (1), R 1 to} R ₄ each independently represent one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a halogen atom. X is -CH _2- , -O-, -S-, -CO-, -C (= O) O-, -O-C (= O)-, -NHCO-, -CONH-, -SO _2- Represents one selected from.)

According to the present invention, it is possible to provide a prepreg capable of producing a fiber-reinforced composite material having excellent tackiness as a prepreg and also having excellent compression characteristics and interlayer toughness.

FIG. 1 is an explanatory diagram showing an outline of a cross section of the prepreg of the present invention. 2 (a), 2 (b) and 2 (c) of FIG. 2 are explanatory views sequentially showing the process of producing the prepreg of the present invention. FIG. 3 is a conceptual diagram showing an example of the manufacturing process of the prepreg of the present invention.

Hereinafter, the present invention will be described in detail.
(1) Structure of prepreg The prepreg of the present invention comprises a primary prepreg composed of a reinforcing fiber base material and an epoxy resin composition A impregnated in the reinforcing fiber layer formed by the reinforcing fiber base material, and the primary prepreg. It is a prepreg in which a surface layer made of an epoxy resin composition B formed on one side or both sides of the prepreg is integrated.

FIG. 1 is an explanatory view showing an outline of a cross section of the prepreg of the present invention. In FIG. 1, 100 is the prepreg of the present invention, and 10 is the primary prepreg. The primary prepreg 10 is composed of a reinforcing fiber layer made of the reinforcing fibers 11 and an epoxy resin composition A13 impregnated in the reinforcing fiber layer. On the surface of the primary prepreg 10, a resin layer made of the epoxy resin composition B15 is formed integrally with the primary prepreg 10.

In the prepreg of the present invention, from the viewpoint of obtaining good tackiness and stability at room temperature, it is contained in the epoxy resin contained in the epoxy resin composition A constituting the primary prepreg and the epoxy resin composition B constituting the surface layer. The mass ratio of the epoxy resin is preferably 9: 1 to 1: 1.

(2) Primary prepreg In the present invention, the primary prepreg is a layer composed of a sheet-shaped fiber-reinforced base material in the central portion of the prepreg cross section and an epoxy resin composition A impregnated in the reinforced fiber base material. The primary prepreg is represented as the primary prepreg 10 in FIGS. 2 (b) and 2 (c).

The reinforcing fiber base material used for the primary prepreg is a base material obtained by processing the reinforcing fibers into various shapes. The reinforcing fiber base material is preferably in the form of a sheet. As the reinforcing fiber, for example, carbon fiber, glass fiber, aramid fiber, silicon carbide fiber, polyester fiber, ceramic fiber, alumina fiber, boron fiber, metal fiber, mineral fiber, rock fiber and slug fiber can be used. Among these reinforcing fibers, carbon fiber, glass fiber, and aramid fiber are preferable, and carbon fiber is more preferable and excellent in tensile strength because a lightweight and high-strength composite material having good specific strength and specific elastic coefficient can be obtained. Therefore, PAN-based carbon fiber is particularly preferable.

When the reinforcing fiber is a carbon fiber, the tensile elastic modulus of the carbon fiber is preferably 170 to 600 GPa, more preferably 220 to 450 GPa. The tensile strength of this carbon fiber is preferably 3920 MPa or more. By using the carbon fiber satisfying this condition, the mechanical properties of the composite using the prepreg of the present invention can be improved.

Examples of the sheet-shaped reinforcing fiber base material include a sheet-like material 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, and a braid. An example is a paper made from reinforcing fibers. The thickness of the sheet-shaped reinforcing fiber base material is, for example, 0.01 to 3 mm, preferably 0.1 to 1.5 mm.

(3) Epoxy resin composition A
Hereinafter, each component used in the epoxy resin composition A will be described.

(I) Epoxy resin The epoxy resin composition A used in the present invention contains an epoxy resin having an epoxy equivalent of 120 g / eq or less. The content of the epoxy resin having an epoxy equivalent of 120 g / eq or less in the epoxy resin composition A is 60 to 100% by weight, preferably 70 to 90% by weight, based on the total weight of the epoxy resin composition A. By including an epoxy resin having an epoxy equivalent of 120 g / eq or less in this range, high resin impregnation property can be obtained at the time of producing a prepreg, and the elastic modulus of the cured resin is improved, so that the prepreg can be manufactured using the prepreg of the present invention. Various physical properties of the composite can be improved.

Epoxy resins having an epoxy equivalent of 120 g / eq or less include, for example, triglycidylaminophenol, tetraglycidyl-m-xylylenediamine, tetraglycidylbis (aminomethyl) cyclohexane, and glycidylamine-type epoxies such as derivatives thereof. A resin can be used, and among them, an epoxy resin containing an aromatic group such as triglycidylaminophenol and tetraglycidyl-m-xylylenediamine is preferably used, and particularly triglycidylaminophenol and its derivatives such as 3 It is preferable to use a functional epoxy resin.

Per total amount of epoxy resin contained in epoxy resin composition A and epoxy resin composition B (hereinafter, also referred to as "total epoxy resin amount") in order to develop excellent composite physical properties after curing and molding of the prepreg. The epoxy resin having a trifunctional group is preferably contained in an amount of 30% by mass or more, more preferably 30 to 70% by mass. If the amount of the trifunctional epoxy resin is less than 30% by mass, the compression characteristics may be deteriorated, which is not preferable. On the other hand, if it is more than 70% by mass, the handleability of the obtained prepreg may be deteriorated, which is not preferable.

The epoxy resin is crosslinked by a thermosetting reaction with the curing agent to form a network structure. By using a trifunctional epoxy resin, a composite having a high crosslink density can be obtained. Examples of the trifunctional epoxy resin include N, N, O-triglycidyl-p-aminophenol and N, N, O-triglycidyl-m-aminophenol.

As long as the content of the epoxy resin having an epoxy equivalent of 120 g / eq or less in the epoxy resin composition A is within the above range, other epoxy resins may be further contained. As the other epoxy resin, a conventionally known epoxy resin can be used. Specifically, those exemplified below can be used. Among these, an epoxy resin containing an aromatic group is preferable, and an epoxy resin containing either a glycidylamine structure or a glycidyl ether structure is preferable. Further, an alicyclic epoxy resin can also be preferably used.

Epoxy resins containing a glycidylamine structure include tetraglycidyldiaminodiphenylmethane, N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-m-aminophenol, N, N, O-. Examples thereof include triglycidyl-3-methyl-4-aminophenol and various isomers of triglycidylaminocresol.

Examples of the epoxy resin containing the glycidyl ether structure include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin.

Further, these epoxy resins may have a non-reactive substituent in the aromatic ring structure or the like, if necessary. Examples of the non-reactive substituent include an alkyl group such as methyl, ethyl and isopropyl, an aromatic group such as phenyl, an alkoxyl group, an aralkyl group, and a halogen group such as chlorine and bromine.

(Ii) Thermoplastic Resin The epoxy resin composition A preferably contains an epoxy resin-soluble thermoplastic resin. Further, the epoxy resin composition A preferably contains an epoxy resin-insoluble thermoplastic resin. A particularly preferred embodiment is an embodiment in which the epoxy resin composition A contains both an epoxy resin-soluble thermoplastic resin and an epoxy resin-insoluble thermoplastic resin.

Some of the epoxy resin-insoluble thermoplastic resin and the epoxy resin-soluble thermoplastic resin (the epoxy resin-soluble thermoplastic resin remaining undissolved in the cured matrix resin) are produced by using the prepreg of the present invention. It is in a state of being dispersed in the matrix resin of the composite (hereinafter, these dispersed particles may be referred to as "interlayer particles"). These interlayer particles suppress the propagation of the impact received by the composite. Therefore, when the epoxy resin composition A contains the epoxy resin-soluble thermoplastic resin or the epoxy resin insoluble thermoplastic resin, the impact resistance of the composite obtained from the prepreg of the present invention can be improved.

(Ii-1) Epoxy resin-soluble thermoplastic resin When the epoxy resin composition A contains the epoxy resin-soluble thermoplastic resin, the viscosity of the epoxy resin composition is adjusted and the impact resistance of the obtained composite is improved. ..

The epoxy resin-soluble thermoplastic resin is a thermoplastic resin that can be partially or wholly dissolved in the epoxy resin at a temperature at which the composite is formed using the prepreg of the present invention or lower. Here, the fact that a part of the particles are dissolved in the epoxy resin means that the particles are mixed with 100 parts by mass of the epoxy resin and 10 parts by mass of the thermoplastic resin having an average particle diameter of 20 to 50 μm and stirred at 190 ° C. for 1 hour. Means that disappears or the size of the particles changes by 10% or more.

When the epoxy resin-soluble thermoplastic resin is not completely dissolved, it can be dissolved in the epoxy resin by being heated in the curing process of the epoxy resin, and the viscosity of the epoxy resin composition can be increased. This makes it possible to prevent the flow of the epoxy resin composition (a phenomenon in which the resin composition flows out from the prepreg) due to the decrease in viscosity in the curing process.
The epoxy resin-soluble thermoplastic resin is preferably a resin that dissolves in the epoxy resin at 190 ° C. in an amount of 80% by mass or more.

Specific examples of the epoxy resin-soluble thermoplastic resin include polyethersulfone, polysulfone, polyetherimide, and polycarbonate. These may be used alone or in combination of two or more. As the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition, polyethersulfone or polysulfone having a weight average molecular weight (Mw) in the range of 8000 to 100,000 as measured by gel permeation chromatography is particularly preferable. If the weight average molecular weight (Mw) is smaller than 8000, the impact resistance of the obtained FRP becomes insufficient, and if it is larger than 100,000, the viscosity becomes remarkably high and the handleability may be remarkably deteriorated. The molecular weight distribution of the epoxy resin-soluble thermoplastic resin is preferably uniform. In particular, the polydispersity (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably in the range of 1 to 10, and preferably in the range of 1.1 to 5. More preferred.

The epoxy resin-soluble thermoplastic resin preferably has a reactive group that is reactive with the epoxy resin or a functional group that forms a hydrogen bond. Such an epoxy resin-soluble thermoplastic resin can improve the dissolution stability of the epoxy resin during the curing process. In addition, toughness, chemical resistance, heat resistance and moisture heat resistance can be imparted to the composite obtained after curing the prepreg.

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. It is more preferable to use a hydroxyl group-terminated polyether sulfone because the composite obtained from the prepreg has particularly excellent impact resistance, fracture toughness and solvent resistance.

The content of the epoxy resin-soluble thermoplastic resin contained in the epoxy resin composition A can be appropriately adjusted according to the viscosity. From the viewpoint of processability of the prepreg, it is preferably 5 to 90 parts by mass, more preferably 5 to 40 parts by mass, and particularly preferably 15 to 35 parts by mass with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition A. Is. If it is less than 5 parts by mass, the impact resistance of the composite obtained from the prepreg may be insufficient, which is not preferable. If the content of the epoxy resin-soluble thermoplastic resin is more than 90 parts by mass, the viscosity becomes remarkably high, and the handleability of the prepreg may be remarkably deteriorated, which is not preferable.

The epoxy resin-soluble thermoplastic resin preferably contains a reactive aromatic oligomer having an amine-terminated group (hereinafter, also simply referred to as “aromatic oligomer”).

The epoxy resin composition A has a high molecular weight due to a curing reaction between the epoxy resin and the curing agent during heat curing. The aromatic oligomer dissolved in the epoxy resin composition A causes a reaction-induced phase separation due to the expansion of the two-phase region due to the increase in molecular weight. By this phase separation, a two-phase structure of a resin in which the cured epoxy resin and the aromatic oligomer are co-continuous is formed in the matrix resin. Further, since the aromatic oligomer has an amine terminal group, a reaction with an epoxy resin also occurs. Since each phase in this co-continuous two-phase structure is firmly bonded to each other, the solvent resistance is also improved.

This co-continuous structure absorbs external impacts on the composite obtained from the prepreg and suppresses crack propagation. As a result, composites made with prepregs containing reactive aromatic oligomers with amine-terminated groups have high impact resistance and fracture toughness.

As the aromatic oligomer, a known polysulfone having an amine-terminated group and a polyethersulfone having an amine-terminated group can be used. The amine terminal group is _{preferably a primary amine (-NH 2} ) terminal group.

The aromatic oligomer blended in the epoxy resin composition A preferably has a weight average molecular weight of 800 to 40,000 as measured by gel permeation chromatography. When the weight average molecular weight is less than 8000, the toughness improving effect of the matrix resin is low, which is not preferable. Further, when the weight average molecular weight exceeds 40,000, the viscosity of the resin composition becomes too high, and processing problems such as difficulty in impregnating the resin composition into the reinforcing fiber layer are likely to occur, which is not preferable.

As the aromatic oligomer, a commercially available product such as "Virantage DAMS VW-30500 RP (registered trademark)" (manufactured by Solvay Specialty Polymers) can be preferably used.

The epoxy resin-soluble thermoplastic resin is preferably in the form of particles. By using the particulate epoxy resin-soluble thermoplastic resin, it can be uniformly blended in the resin composition, and a prepreg having high moldability can be obtained.

The average particle size of the epoxy resin-soluble thermoplastic resin is preferably 1 to 50 μm, more preferably 3 to 30 μm. If it is less than 1 μm, the viscosity of the epoxy resin composition may be significantly increased, and it may be difficult to add a sufficient amount of the epoxy resin-soluble thermoplastic resin to the epoxy resin composition, which is not preferable. On the other hand, if it exceeds 50 μm, it may be difficult to obtain a sheet having a uniform thickness when the epoxy resin composition is processed into a sheet, and the dissolution rate in the epoxy resin becomes slow, so that the composition obtained from the pull preg is obtained. It is not preferable because it becomes non-uniform.

(Ii-2) Epoxy Resin Insoluble Thermoplastic Resin The epoxy resin insoluble thermoplastic resin refers to a thermoplastic resin that does not substantially dissolve in the epoxy resin at a temperature at which the composite is formed using the prepreg or lower. That is, 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 an epoxy resin and stirred at 190 ° C. for 1 hour, the size of the particles does not change by 10% or more. Refers to a plastic resin. Generally, the temperature for molding the composite 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 sizes of 100 randomly selected particles.

Examples of the epoxy resin-insoluble thermoplastic resin include polyamide, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyester, polyamideimide, polyimide, polyetherketone, polyetheretherketone, polyethylene naphthalate, 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 composites. These may be used alone or in combination of two or more. Moreover, these copolymers can also be used.

In particular, amorphous polyimide, polyamide 6 (polyamide obtained by the ring-opening polycondensation reaction of caprolactam), polyamide 11 (polyamide obtained by the ring-opening polycondensation reaction of undecanlactam), and polyamide 12 (ring-opening weight of lauryllactam). Polyamide obtained by condensation reaction), polyamide 1010 (polyamide obtained by co-weight reaction of sebacic acid and 1,10-decanediamine), amorphous polyamide (also called transparent polyamide, and polymer crystallization does not occur. Alternatively, the heat resistance of the composite obtained from the prepreg can be improved by using a polyamide such as (polyamide) in which the crystallization rate of the polymer is extremely slow.

The content of the epoxy resin-insoluble thermoplastic resin in the epoxy resin composition A is appropriately adjusted according to the viscosity of the epoxy resin composition. From the viewpoint of processability of the prepreg, it is preferably 5 to 50 parts by mass, more preferably 10 to 45 parts by mass, and particularly preferably 20 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin contained in the epoxy resin composition A. It is a department. If it is less than 5 parts by mass, the impact resistance of the obtained FRP may be insufficient, which is not preferable. 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, which is not preferable.
The preferable average particle size and morphology of the epoxy resin-insoluble thermoplastic resin are the same as those of the epoxy resin-soluble thermoplastic resin.

(Iii) Other Additives The epoxy resin composition A may contain conductive particles, a flame retardant, an inorganic filler, and an internal mold release agent.

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 materials. 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. As the phosphorus-based flame retardant, those containing a phosphorus atom in the molecule can be used, and examples thereof include organic phosphorus compounds such as phosphoric acid esters, condensed phosphoric acid esters, phosphazenic compounds and polyphosphates, and red phosphorus.

Examples of the inorganic filler include aluminum borate, calcium carbonate, silicon carbonate, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, calcium sulfate, magnesium borate, magnesium oxide, and silicate minerals. Can be mentioned. In particular, it is preferable to use silicate minerals. Examples of commercially available silicate minerals include THIXOTOPIC AGENT DT 5039 (manufactured by Huntsman Japan Co., Ltd.).

Examples of the internal mold release agent include metal soaps, vegetable waxes such as polyethylene wax and carbana wax, fatty acid ester mold release agents, silicon oil, animal wax, and fluorine-based nonionic surfactants. The blending amount of these internal mold release agents is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the epoxy resin composition A from the viewpoint of preferably exerting the mold release effect from the mold. Is 0.2 to 2 parts by mass.

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

(Iv) Curing Agent The epoxy resin composition A further contains a curing agent for an epoxy resin, and the content of the curing agent is 150 to 300% of the total amount of the epoxy resin contained in the epoxy resin composition A. ..

The content of the curing agent is 150 to 300% as an equivalent ratio to the total amount of the epoxy resin contained in the epoxy resin composition A, which means that the equivalent ratio in the epoxy resin composition A (epoxy value of the epoxy resin / curing agent). It means that the active hydrogen value) is 150 to 300%.

As the curing agent used in the epoxy resin composition A, a known curing agent for epoxy resin can be used. Above all, it is preferable to use an amine-based curing agent. Examples of the amine-based curing agent include dicyandiamide, various isomers of the aromatic amine-based curing agent, and aminobenzoic acid esters.

Dicyanodiamide is preferable because it has excellent storage stability of prepreg. In addition, aromatic diamine compounds such as 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenylmethane and derivatives having non-reactive substituents thereof have good heat resistance. It is particularly preferable because it gives a good cured product. Here, the non-reactive substituent is the same as the non-reactive substituent described in the description of the epoxy resin.

As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. The composite material cured using these is inferior in heat resistance as compared with various isomers of diaminodiphenyl sulfone, but is excellent in tensile elongation. Therefore, the type of curing agent to be used is appropriately selected according to the use of the composite material.

The amount of the curing agent contained in the epoxy resin composition A is 150 to 300%, preferably 170 to 250, as an equivalent ratio to the total amount of the epoxy resin contained in the epoxy resin composition A from the viewpoint of curing all the epoxy resins. %. The amount of the curing agent may be appropriately adjusted according to the type of the epoxy resin and the curing agent used in the above range. The amount of the curing agent is appropriately adjusted in consideration of the presence / absence and addition amount of the curing agent / curing accelerator, the stoichiometry with the epoxy resin, the curing rate of the composition, and the like.

(4) Epoxy resin composition B
The epoxy resin composition B contains an epoxy resin represented by the chemical formula (1). This epoxy resin composition B is a component constituting the surface layer 15a of the prepreg of the present invention in FIG. 2C. Hereinafter, each component used in the epoxy resin composition B will be described.

(I) Epoxy resin The epoxy resin composition B contains an epoxy resin represented by the following chemical formula (1).

(However, in Chemical _{formula (1), R 1 to} R ₄ each independently represent one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a halogen atom. X is -CH _2- , -O-, -S-, -CO-, -C (= O) O-, -O-C (= O)-, -NHCO-, -CONH-, -SO _2- Represents one selected from.)
When R _{1 to} R ₄ are an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, the number of carbon atoms thereof is preferably 1 to 4.

The epoxy resin represented by the chemical formula (1) is a tetrafunctional epoxy resin, and an amino group having two glycidyl groups is bonded to the diaminodiphenyl skeleton at the para-position and the meta-position, respectively. The present inventors presume that the elastic modulus and heat resistance of the cured resin are increased due to the special three-dimensional structure of the cured resin generated by this structure.

The epoxy resin represented by the chemical formula (1) is preferably tetraglycidyl-3,4'-diaminodiphenyl ether. When R _{1 to} R ₄ are hydrogen atoms, it is preferable because the formation of a special three-dimensional structure of the cured resin is not easily hindered. Further, it is preferable that X is −O− because the synthesis of the compound is facilitated.

The ratio of the epoxy resin represented by the chemical formula (1) to the total amount of the epoxy resin in the epoxy resin composition B is preferably 20 to 95% by mass, more preferably 25 to 90% by mass, and particularly preferably 30 to 85. It is mass%. If it is less than 20% by mass, the heat resistance and elastic modulus of the obtained cured resin may decrease, which is not preferable. On the other hand, if it exceeds 95% by mass, the viscosity of the epoxy resin composition is high, the impregnation property into the fiber-reinforced base material tends to decrease, and various physical properties of the C composite obtained from the prepreg may decrease, which is not preferable.

From the viewpoint of tackiness, the epoxy resin composition B preferably contains substantially no curing agent for the epoxy resin. Here, substantially not contained means that the content of the curing agent in the total weight of the composition is 40% by weight or less, preferably 10% by weight or less, and more preferably 1% by weight or less. ..

(Ii) Thermoplastic Resin The epoxy resin composition B may contain a thermoplastic resin dissolved in the epoxy resin. This thermoplastic resin is the epoxy resin-soluble thermoplastic resin already described. The epoxy resin-soluble thermoplastic resin blended in the epoxy resin composition B may be the same as the epoxy resin-soluble thermoplastic resin blended in the epoxy resin composition A, or may be different from each other. ..

When the epoxy resin-soluble thermoplastic resin is contained in the epoxy resin composition B, it is preferably 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the epoxy resin contained in the epoxy resin composition B. .. If it is less than 5 parts by mass, the impact resistance of the obtained prepreg and the composite material may be insufficient, which is not preferable. On the other hand, if it exceeds 50 parts by mass, the viscosity may become extremely high and the handleability may be significantly deteriorated, which is not preferable.

(Iii) Other Additives The epoxy resin composition B may further contain conductive particles, a flame retardant, an inorganic filler, and an internal mold release agent as described above.

(5) Method for Producing Epoxy Resin Composition The epoxy resin composition A and the epoxy resin composition B can be produced by mixing the epoxy resin of the epoxy resin composition A and the components constituting the epoxy resin composition B. can. The order of mixing these is not limited. Conventionally known methods can be applied, and the mixing temperature is, for example, 40 to 120 ° C, preferably 50 to 100 ° C, and more preferably 50 to 90 ° C. When the temperature exceeds 120 ° C., the curing reaction partially proceeds and the impregnation property into the reinforcing fiber base material layer is lowered, or the storage stability of the obtained epoxy resin composition and the prepreg produced using the same is improved. May decrease. If the temperature is lower than 40 ° C., the viscosity of the epoxy resin composition may be high, which may make mixing substantially difficult.

Conventionally known mixing machinery can be used for mixing. Specific examples include a roll mill, a planetary mixer, a kneader, an extruder, a Banbury mixer, a mixing vessel equipped with a stirring blade, and a horizontal mixing tank. 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. For example, it is preferable to mix in a temperature controlled to a constant temperature of 30 ° C. or lower or in a low humidity atmosphere having a relative humidity of 50% RH or less.

(6) Method for producing prepreg The prepreg of the present invention can be produced by using the above-mentioned epoxy resin composition A and epoxy resin composition B by a conventionally known method. It is preferably produced by a dry method in which the reinforcing fiber layer is impregnated with the resin composition A whose viscosity has been reduced by heating. Such a dry method is preferable because no organic solvent remains as compared with a wet method in which the epoxy resin composition A dissolved in an organic solvent is impregnated into the reinforcing fiber layer and then the organic solvent is removed. Hereinafter, the method for producing the prepreg of the present invention will be described by the method for producing the prepreg by the dry method.

First, a film made of the epoxy resin composition A (hereinafter referred to as "resin A film") and a film made of the epoxy resin composition B (hereinafter referred to as "resin B film") are produced. This can be done by a known method.

Next, the resin A film is laminated on one side or both sides in the thickness direction of the reinforcing fiber layer, and heat-pressed by a heat roller or the like. As a result, the epoxy resin composition A of the resin A film is impregnated in the reinforcing fiber layer to obtain a primary prepreg. After that, the resin B film is laminated on one side or both sides of the primary prepreg in the thickness direction and hot-pressed by a hot roller or the like to integrate the primary prepreg and the resin B film. Thereby, the prepreg of the present invention can be obtained.

2 (a) to 2 (c) are explanatory views sequentially showing the process of manufacturing the prepreg of the present invention. First, the resin A film 13a made of the epoxy resin composition A is laminated on both sides of the reinforcing fiber layer 12 made of the reinforcing fiber 11 in the thickness direction (FIG. 2A). The reinforcing fiber layer 12 and the resin A film 13a are hot-pressed by a hot roller or the like. As a result, the epoxy resin composition A is impregnated into the reinforcing fiber layer 12, and the primary prepreg 10 is obtained (FIG. 2 (b)). Then, a resin B film 15a made of the epoxy resin composition B is laminated on one side or both sides of the primary prepreg 10 in the thickness direction (FIG. 2 (c)). Then, it is hot-pressed by a hot roller or the like to integrate the primary prepreg 10 and the resin B film 15a. As a result, the prepreg 100 of the present invention is obtained (FIG. 1).

FIG. 3 is a conceptual diagram showing an example of the manufacturing process of the prepreg of the present invention. In FIG. 3, 21 is a reinforcing fiber layer in which carbon fibers are aligned in one direction, and runs in the direction of arrow A. The resin A film 13a with the release paper 14a is supplied from the film roll 23 on both sides of the reinforcing fiber layer 21 in the thickness direction. The reinforcing fiber layer 21 and the resin A film 13a are hot-pressed by a heat roller 40 via a release paper 14a to form a primary prepreg 10. After that, the release paper 14a on one side or both sides of the primary prepreg is wound around the roller 24. Next, the resin B film 15a with the release paper is supplied from the film roll 25 to one side or both sides of the primary prepreg 10 on which the release paper is wound. The primary prepreg 10 and the resin B film 15a are hot-pressed by a heat roller 41 via a release paper to form the prepreg 100 of the present invention. The prepreg 100 is wound around a roller 101.

The temperature of the resin A film during hot pressing is, for example, 70 to 160 ° C, preferably 70 to 140 ° C. When the temperature of the resin A film during hot pressing is less than 70 ° C., the viscosity of the epoxy resin composition A constituting the resin A film does not sufficiently decrease. As a result, it is difficult to sufficiently impregnate the epoxy resin composition A into the reinforcing fiber layer.

The linear pressure of the resin A film during hot pressing is, for example, 1 to 25 kg / cm, preferably 2 to 15 kg / cm. When the linear pressure of the resin A film during hot pressing is less than 1 kg / cm, it is difficult to sufficiently impregnate the reinforcing fiber layer with the resin composition A constituting the resin A film. If the linear pressure of the resin A film during hot pressing exceeds 25 kg / cm, the reinforcing fibers themselves are damaged and the impregnation pressure cannot be increased.

The temperature of the resin B film during hot pressing is, for example, 50 to 130 ° C, preferably 60 to 120 ° C. If the temperature of the resin B film during hot pressing is less than 50 ° C., the surface tack is too strong, the releasability of the resin film deteriorates, and the process stability of the prepreg production may be impaired. When the temperature of the resin B film during hot pressing exceeds 130 ° C., it mixes with the epoxy resin composition A used in the primary prepreg, and the reaction proceeds. As a result, when stored for a long period of time, tackiness and drapeability are impaired.

The linear pressure of the resin B film during hot pressing is, for example, 0.1 to 10 kg / cm, preferably 0.5 to 6 kg / cm. If the linear pressure of the resin B film during hot pressing is less than 0.1 kg / cm, the resin B film cannot be sufficiently adhered to the primary prepreg. When the linear pressure at the time of hot pressing exceeds 10 kg / cm, the reaction with the curing agent proceeds due to the subduction into the epoxy resin composition A used for the primary prepreg. As a result, when stored for a long period of time, tackiness and drapeability are impaired.

In the prepreg of the present invention produced by the above production method, the epoxy resin composition A13 is present in the reinforcing fiber layer as shown in FIG.
The production rate of the prepreg is, for example, 0.1 m / min or more, preferably 1 m / min or more, more preferably 5 m / min or more, in consideration of productivity and economy.

The resin A film and the resin B film can be produced by known methods. For example, it can be created by casting and casting on a support such as a release paper or a film by a die coater, an applicator, a reverse roll coater, a comma coater, a knife coater or the like. The resin temperature at the time of film formation can be appropriately set according to the resin composition and viscosity.

The thickness of the resin B film is preferably 2 to 30 μm, more preferably 5 to 20 μm. If the thickness of the resin B film is less than 2 μm, the tackiness of the obtained prepreg is lowered, which is not preferable. If the thickness of the resin B film exceeds 30 μm, the handleability of the obtained prepreg and the molding accuracy of the composite are lowered, which is not preferable.

The prepreg of the present invention is not limited to the above-mentioned production method, and can be produced, for example, by sequentially laminating a resin A film and a resin B film on both sides in the thickness direction of the reinforcing fiber layer and heat-pressing them in one step. .. In this case, it is necessary to perform hot pressing at a low temperature so that the curing agent contained in the epoxy resin composition B does not diffuse into the epoxy resin composition A.
The prepreg of the present invention may contain stabilizers, mold release agents, fillers, colorants and the like as long as the effects of the present invention are not impaired.

In the prepreg of the present invention, the content of the reinforcing fiber is preferably 40 to 80% by mass, more preferably 50 to 70% by mass. When the content of the reinforcing fiber is less than 40% by mass, the strength of the composite produced by using this prepreg is insufficient, which is not preferable. When the content of the reinforcing fibers exceeds 80% by mass, the amount of the resin impregnated in the reinforcing fiber layer of the prepreg is insufficient, and as a result, voids and the like are generated in the composite produced using the prepreg, which is preferable. No.

In the prepreg of the present invention, the curing agent contained in the epoxy resin composition B is diffused into the epoxy resin composition A by heating while applying pressure. As a result, both the epoxy resin composition A and the epoxy resin composition B are cured.

(7) Fiber-reinforced composite material By heating and pressurizing the prepreg of the present invention under specific conditions and curing it, a fiber-reinforced composite material (composite) can be obtained. As a method for producing a composite using the prepreg of the present invention, known molding methods such as autoclave molding and press molding can be mentioned.

(I) Autoclave molding method When producing a composite using the prepreg of the present invention, the autoclave molding method can be 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. At the same time, it is a molding method that heats and pressurizes with an autoclave molding device. The conditions at the time of molding are preferably 1 to 50 ° C./min and heating and pressurization at 0.2 to 0.7 MPa and 130 to 180 ° C. for 10 to 300 minutes.

(Ii) Press molding method As another method for producing a composite using the prepreg of the present invention, a press molding method can be preferably used. The fiber-reinforced composite material produced by the press molding method is produced by heating and pressurizing the prepreg of the present invention or the preform formed by laminating the prepreg of the present invention using a mold. It is preferable that the mold is preheated to a curing temperature.

The temperature of the mold during press molding is preferably 150 to 210 ° C. Molding temperature is 150
When the temperature is above ° C, a sufficient curing reaction can occur, 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, it is possible to suppress the outflow of resin from the mold and the meandering of fibers, so that a high-quality composite can be obtained.

The pressure at the time of molding is, for example, 0.05 to 2 MPa, preferably 0.2 to 2 MPa. When the pressure is 0.05 MPa or more, an appropriate flow of the resin can be obtained, and poor appearance and generation of voids can be prevented. In addition, since the prepreg is sufficiently adhered to the mold, a composite having a good appearance can be manufactured. When the pressure is 2 MPa or less, the resin does not flow more than necessary, so that the appearance of the obtained FRP 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, for example, 1 to 8 hours.

Hereinafter, the present invention will be described in more detail by way of examples. The components and test methods used in this example and comparative examples are described below.
〔component〕
The details of the components used are as follows.

(Epoxy resin)
-Tetraglycidyl-4,4'-diaminodiphenylmethane (Huntsman Corporation Araldite MY721, number of glycidyl ethers / number of aromatic rings = 0, epoxy equivalent = 112 g / eq, hereinafter abbreviated as "4,4'-TGDDM")
Tetraglycidyl-3,4'-diaminodiphenyl ether (synthesized by the method of Synthesis Example 1 below. Represented by chemical conversion (1). Epoxy equivalent = 112 g / eq, hereinafter "3,4'-TGDDE". Abbreviated)

Triglycidyl-m-aminophenol (Araldite MY0600 manufactured by Huntsman Corporation, number of glycidyl ethers / number of aromatic rings = 1, epoxy equivalent = 106 g / eq, hereinafter abbreviated as "TG-mAP")
-Resorcinol diglycidyl ether (EX-201 manufactured by Nagase ChemteX, number of glycidyl ethers / number of aromatic rings = 2, epoxy equivalent = 115 g / eq, hereinafter abbreviated as "Resorcinol-DG")

(Amine-based curing agent)
・ 3,3'-Diaminodiphenyl sulfone (manufactured by Konishi Chemical Industry Co., Ltd., hereinafter abbreviated as "3,3'-DDS")

(Epoxy resin insoluble thermoplastic resin)
-TR-55 (trade name): (Grill amide manufactured by Ems-Chemie Japan, average particle diameter 5 to 35 μm, hereinafter abbreviated as "TR-55")
-VEST0SINT 2158 (trade name): (Polyamide 12, manufactured by Daicel Evonik, average particle diameter 5 to 35 μm, hereinafter abbreviated as "PA12")

(Epoxy resin-soluble thermoplastic resin)
-Polyether sulfone (Sumika Excel PES-5003P manufactured by Sumitomo Chemical Co., Ltd., average particle size 20 μm, hereinafter abbreviated as “PES”)

(Carbon fiber)
Tenax (registered trademark) IMS65 E23 830tex: (carbon fiber strand, tensile strength 5.8 GPa, tensile elastic modulus 290 GPa, manufactured by Teijin Limited)
Tenax (registered trademark) IMS65 E22 830tex (carbon fiber strand, tensile strength 5.8 GPa, tensile elastic modulus 290 GPa, sizing agent adhesion 0.5% by mass, manufactured by Teijin Limited)

(Synthesis Example 1) Synthesis of 3,4'-TGDDE 3,4'-TGDDE was synthesized by the following method. In a four-necked flask equipped with a thermometer, a dropping funnel, a condenser and a stirrer, 1110.2 g (12.0 mol) of epichlorohydrin was charged, and the temperature was raised to 70 ° C while purging nitrogen, and ethanol was added to this. 200.2 g (1.0 mol) of 3,4'-diaminodiphenyl ether dissolved in 1000 g was added dropwise over 4 hours. The addition reaction was completed with further stirring for 6 hours to obtain N, N, N', N'-tetrakis (2-hydroxy-3-chloropropyl) -3,4'-diaminodiphenyl ether. Subsequently, the temperature inside the flask was lowered to 25 ° C., 500.0 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 washing was performed 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%).

(1) Properties of prepreg (1-1) Impregnation property The impregnation property of the resin into the fiber substrate was evaluated by the water absorption rate of the prepreg. In this evaluation, the lower the water absorption rate of the obtained prepreg, the higher the impregnation property of the resin.
The prepreg was cut into squares with a side of 100 mm, and the mass (W ₁ ) was measured. Then, in a desiccator, the prepreg was submerged in water. The inside of the desiccator was depressurized to 10 kPa or less to replace the air and water inside the prepreg. The prepreg was taken out of the water, the water on the surface was wiped off, and the mass (W ₂ ) of the prepreg was measured. Formula water absorption from these measurements _{(%) = [(W 2} -W 1) / W 1] × 100
W ₁ : Mass of prepreg (g)
W ₂ : Mass of prepreg after water absorption (g)
The water absorption rate was calculated using the following criteria and evaluated according to the following criteria.
◯: Water absorption rate is less than 10%.
×: Water absorption rate is 10% or more

(1-2)
The prepreg was stored at a temperature of 26.7 ° C. and a humidity of 65% for 10 days.

(2) Physical characteristics of prepreg processed products (2-1) Perforated compressive strength (OHC)
The prepreg obtained in (1-2) above 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 38.1 mm in width × 304.8 mm in length, and a hole with a diameter of 6.35 mm was formed in the center of the test piece to obtain a test piece for a perforated compressive strength (OHC) test. .. The test piece and the test were measured according to SACMA SRM3, and the perforated compressive strength was calculated from the maximum point load.

(2-2) Hot-wet OHC
The prepreg obtained in (1-2) above 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 38.1 mm in width × 304.8 mm in length, and a hole with a diameter of 6.35 mm was formed in the center of the test piece to obtain a test piece for a perforated compressive strength (OHC) test. .. Using a pressure cooker (HASTEST PC-422R8 manufactured by ESPEC), the OHC test piece prepared at 121 ° C. for 72 hours was subjected to water absorption treatment.
The test was carried out according to SACMA SRM3, and the perforated compressive strength was calculated from the maximum point load. The measurement was performed at 104 ° C and 121 ° C.

(2-3) Interlayer fracture toughness mode I (GIc)
The prepreg obtained in (1-2) above 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 was cut into dimensions having a width of 25.0 mm and a length of 160.0 mm 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 2 to 5 mm from the tip of the release sheet, and then further develop the crack. Was done. The test was carried out according to JIS K 7086, and the measurement was carried out at n = 5.

(2-4) Volume resistivity in the Thickness Direction The prepreg obtained in (1-2) above is cut into a square having a side of 360 mm and laminated to form a laminated body having _{a laminated structure [+ 45/0 / -45/90] 4S.} Obtained. 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 into dimensions having a width of 40.0 mm and a length of 40.0 mm to obtain a test piece for measuring the volume resistivity in the thickness direction. A voltage was applied between the front surface and the back surface of the test piece, and the volume resistivity in the thickness direction (Ω · cm) was measured. The measurement was performed using a digital ohm meter.

[Example 1]
The thermoplastic resin (PES5003P and PA-12) was dissolved in the epoxy resin (TG-mAP) at 120 ° C. using a stirrer. Then, the temperature was lowered to 80 ° C. and mixed for 30 minutes. Then, a curing agent (3,3'-DDS) was added and mixed for 30 minutes to prepare an epoxy resin composition A. The types and amounts of the components used were as shown in Table 1.

Further, the epoxy resin (TG-mAP) was added to the epoxy resin (3,4'-TGDDE) using a stirrer, and the thermoplastic resin (PES5003P) was dissolved at 120 ° C. Then, the temperature was lowered to 80 ° C. and mixed for 30 minutes to prepare an epoxy resin composition B. The types and amounts of the components used were as shown in Table 1.

An epoxy resin composition A was applied onto a release paper using a reverse roll coater to prepare a resin film A. Further, the epoxy resin composition B was applied onto the release paper using a reverse roll coater to prepare a resin film B. Basis weight, 60 g / ^{m 2} of resin film A, a resin film B was 40 g / ^{m 2.}

Next, the carbon fiber strands are uniformly arranged (graining 190 g / m ² ) in one direction between the two resin A films and supplied, and the temperature is 70 to 140 ° C. and the pressure is 10 kg / cm using a roller. Pressurized and heated to obtain a primary prepreg.
Then, the primary prepreg is supplied between two resin B films, pressurized and heated at a temperature of 60 to 120 ° C. and a pressure of 1.5 kg / cm using a roller, and wound on a roll to obtain a prepreg. rice field.

The content of the resin with respect to the entire prepreg was 35% by mass. Table 1 shows various performances of the obtained prepreg. In Example 1, very high values were obtained for the composite physical characteristics, and the tackiness was also good.

[Example 2]
In Example 1, TG-mAP and 4,4'-TGDDM were used as the epoxy resin used in the epoxy resin composition A in the amounts shown in Table 1, and the curing agent (3,3'-DDS) was used in the amounts shown in Table 1. A prepreg was obtained by carrying out the same procedure as in Example 1 except that the prepreg was added in 1.

[Comparative Examples 1 to 4]
A prepreg was obtained in the same manner as in Example 1 except that the components and amounts used to obtain the epoxy resin composition A and the epoxy resin composition B were changed to those shown in Table 1.

In Comparative Example 1, since the trifunctional glycidylamine type epoxy resin TG-mAP (MY0600) was not present in the impregnated layer (inner layer), the mechanical properties OHC and Hot-wet OHC of the composite were lowered.

In Comparative Example 4, the trifunctional glycidylamine type epoxy resin TG-mAP (MY0600) was not present in the impregnated layer (inner layer), and the tetrafunctional glycidylamine type epoxy resin 3,4'-TGDDE was present in the tack layer (surface layer). Therefore, the mechanical properties of the composite, OHC and Hot-wet OHC, were lowered.

The prepreg of the present invention can be used for producing a fiber-reinforced composite material (composite).

100 ... prepreg 10 ... primary prepreg 11 ... carbon fiber 12 ... reinforced fiber layer 13 ... epoxy resin composition A
13a ... Resin A film 14a ... Release paper 15 ... Epoxy resin composition B
15a ... Resin B film 21 ... Reinforcing fiber layer 23 ... Resin A film roll 24 ... Release paper winding roll 25 ... Resin B film roll 40, 41 ... Thermal roller 101 ... Prepreg take-up roll

Claims (10)

A primary prepreg composed of a reinforcing fiber base material and an epoxy resin composition A impregnated in the reinforcing fiber layer formed by the reinforcing fiber base material, and an epoxy resin composition formed on one or both sides of the primary prepreg. A prepreg comprising a surface layer composed of the substance B, wherein the epoxy resin composition A and the epoxy resin composition B each have the following formulations.
Epoxy resin composition A:
An epoxy containing an epoxy resin having an epoxy equivalent of 120 g / eq or less and a curing agent for the epoxy resin, and the content of the curing agent is 150 to 300% as an equivalent ratio to the total amount of the epoxy resin contained in the epoxy resin composition A. Resin composition Epoxy resin composition B:
An epoxy resin composition containing an epoxy resin represented by the following chemical formula (1).

(However, in Chemical _{formula (1), R 1 to} R ₄ each independently represent one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a halogen atom. X is -CH _2- , -O-, -S-, -CO-, -C (= O) O-, -O-C (= O)-, -NHCO-, -CONH-, -SO _2- Represents one selected from.) The prepreg according to claim 1, wherein the epoxy resin composition B contains substantially no curing agent for the epoxy resin. The prepreg according to claim 2, wherein 30% by mass or more of the total amount of the epoxy resins contained in the epoxy resin composition A and the epoxy resin composition B is a trifunctional epoxy resin. The prepreg according to any one of claims 1 to 3, wherein the epoxy resin composition A further contains an epoxy resin-soluble thermoplastic resin. The prepreg according to claim 4, wherein the epoxy resin-soluble thermoplastic resin is polyethersulfone, polysulfone, polyetherimide or polycarbonate. The prepreg according to any one of claims 1 to 5, wherein the epoxy resin composition A further contains an epoxy resin insoluble thermoplastic resin. The prepreg according to claim 6, wherein the epoxy resin-insoluble thermoplastic resin is an amorphous polyamide, a polyamide 6, a polyamide 12, or an amorphous polyimide. The prepreg according to any one of claims 1 to 7, wherein the curing agent contained in the epoxy resin composition A is an aromatic diamine compound. The prepreg according to claim 8, wherein the aromatic diamine compound is 3,3'-diaminodiphenyl sulfone. The prepreg according to any one of claims 1 to 9, wherein the reinforcing fiber base material is made of carbon fiber.

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