JP7255493B2 - Fiber reinforced composite material and cured product using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fiber-reinforced composite material and a cured product using the same.

A fiber-reinforced composite material is a composite material whose strength is improved by adding reinforcing fibers such as glass fibers into a matrix resin. Although the matrix resin is lightweight, it has a low elastic modulus by itself and is not suitable for use as a structural material. can be done.

Fiber-reinforced composite materials exhibit different physical properties depending on differences in fiber, resin, additives, prepreg manufacturing method, resin pellet manufacturing method, molding method, etc. Therefore, research and development is being promoted on each raw material and manufacturing method. there is

For example, fibers are generally added to the matrix resin in the form of reinforcing fiber bundles in which a plurality of reinforcing fibers are bundled with a sizing agent (sizing agent). By having the form of a reinforcing fiber bundle, the shape retainability is improved, and the dispersibility in the matrix resin and the like can be improved.

Since the sizing agent can affect the performance of the fiber-reinforced composite material in this way, various studies have been made so far. For example, in Patent Document 1, a urethane-modified epoxy resin (A) and at least one resin component (B) selected from aromatic polyester resins, aromatic polyester urethane resins, polyamide resins and modified polyolefin resins are described. An invention relating to a sizing agent for reinforcing fibers is described. Patent Literature 1 describes that the sizing agent for reinforcing fibers can impart excellent adhesiveness to the matrix resin and flexibility to the reinforcing fibers at the same time.

In addition, in Patent Document 1, the resin component (B) can dramatically improve the adhesiveness between the reinforcing fiber and the matrix resin by using the resin component (B) together with the urethane-modified epoxy resin (A), and It is also described that excellent softness can be imparted to the reinforcing fibers.

Examples of the matrix resin include epoxy resins, phenol resins, unsaturated polyester resins, vinyl ester resins, cyanate ester resins, thermosetting resins such as polyimide resins, polyolefin resins, polyamide resins, polycarbonate resins, polyester resins, It is described that thermoplastic resins such as polyacetal resins, ABS resins, phenoxy resins, polymethylmethacrylate resins, polyphenylene sulfide resins, polyetherimide resins and polyetherketone resins are used.

WO2014/196372

According to the sizing agent (sizing agent for reinforcing fibers) described in Patent Document 1, certain adhesiveness and flexibility to the matrix resin can be achieved. However, it has been found that the cured product of the fiber-reinforced composite material obtained using the sizing agent described in Patent Document 1 may not have sufficient mechanical properties.

Accordingly, an object of the present invention is to provide a fiber-reinforced composite material in which the resulting cured product has excellent mechanical properties.

The present inventors have conducted intensive research in order to solve the above problems. As a result, the inventors have found that the above problems can be solved by combining a given sizing agent and a given matrix resin, and have completed the present invention.

That is, the present invention relates to a fiber-reinforced composite material including reinforcing fiber bundles having reinforcing fibers and a sizing agent, and a matrix resin. At this time, the sizing agent contains a first bisphenol-type epoxy resin and a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure, and the matrix resin contains a second bisphenol-type epoxy resin and an amine curing agent. Characterized by

According to the present invention, a fiber-reinforced composite material is provided in which the resulting cured product has excellent mechanical properties.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below.

<Fiber reinforced composite material>
A fiber-reinforced composite material according to the present invention includes a reinforcing fiber bundle having reinforcing fibers and a sizing agent, and a matrix resin. At this time, the sizing agent contains a first bisphenol-type epoxy resin and a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure, and the matrix resin contains a second bisphenol-type epoxy resin and an amine curing agent.

Conventional fiber-reinforced composite materials consider sizing agents and matrix resins separately. For example, Patent Document 1 discusses a sizing agent, and as described above, a predetermined resin component (B) is used in combination with a predetermined urethane-modified epoxy resin (A) to improve the adhesion between reinforcing fibers and a matrix resin. can be improved. However, the matrix resin actually used is different from the resin component (B), and the affinity between the sizing agent and the matrix resin is not sufficient. As a result, the mechanical properties of the cured product obtained from the fiber-reinforced composite material may not be sufficient.

In contrast, in the fiber-reinforced composite material according to this embodiment, both the sizing agent and the matrix resin contain a bisphenol-type epoxy resin. As a result, the reinforcing fiber bundle-matrix resin has a high affinity, and suitable interface control becomes possible. By selecting a bisphenol A type epoxy resin among the resins, the cured product obtained from the fiber-reinforced composite material has higher mechanical properties.

[Reinforcing fiber bundle]
The reinforcing fiber bundle has reinforcing fibers and a sizing agent. In addition, other sizing agents may be included.

(reinforced fiber)
The reinforcing fiber has a function of imparting strength by being contained in the matrix resin. In this specification, "reinforcing fiber" means a single fiber that constitutes a reinforcing fiber bundle.

Reinforcing fibers include, but are not limited to, carbon fiber, glass fiber, graphite fiber, hemp fiber, kenaf fiber, bamboo fiber, rayon fiber, lyocell fiber, silicon carbide fiber, aluminum fiber, boron fiber, aramid fiber, vinylon fiber, Polyamide fiber, polyethylene fiber, polyester fiber (polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene naphthalate fiber), steel fiber, polyacetal fiber, polyparaphenylenebenzoxazole (PBO) fiber, polyketone fiber, carbon nanofiber, carbon nanotube, cotton fibrils, silicon nitride whiskers, alumina whiskers, silicon carbide whiskers, nickel whiskers and the like.

Among these, the reinforcing fiber is preferably carbon fiber or glass fiber, and more preferably carbon fiber.

The carbon fiber may be polyacrylonitrile (PAN)-based carbon fiber or pitch-based carbon fiber. At this time, the PAN-based carbon fiber contains acrylonitrile as a monomer component together with acrylic acid, methacrylic acid, itaconic acid, and their alkali metal salts, ammonium salts, and alkyl esters; acrylamide and its derivatives; It may contain lylsulfonic acid and salts thereof, alkyl esters and the like. The pitch-based carbon fiber may be either mesofuse pitch-based carbon fiber or isotropic pitch-based carbon fiber.

The reinforcing fibers described above may be used alone or in combination of two or more.

The reinforcing fibers are not particularly limited, but twisted yarns, spun yarns, spun yarns, and non-woven yarns can be used. Specific forms of reinforcing fibers include filaments, yarns, rovings, strands, chopped strands, felts, needle punches, cloths, roving cloths, milled fibers and the like.

(Sizing agent)
The sizing agent has the function of adjusting the degree of bonding between the reinforcing fibers and the matrix resin, the function of retaining the shape of the reinforcing fibers, the function of preventing or suppressing damage to the reinforcing fibers, the function of adjusting the size of the reinforcing fiber bundles, and the like. .

The sizing agent according to the present invention contains a first bisphenol-type epoxy resin and a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure. In addition, it may further contain a first other resin, a surfactant, a solvent, and the like.

The content of the sizing agent is preferably 0.1 to 6.0% by mass, more preferably 0.3 to 4.0% by mass. When the content of the bundling agent is 0.1% by mass or more, it is possible to suppress or prevent fluffing of the reinforcing fiber bundles, thereby improving workability and the like, which is preferable. On the other hand, when the content of the bundling agent is 6.0% by mass or less, it is possible to prevent or suppress the deterioration of the fiber opening property of the reinforcing fiber bundle, and the strength of the reinforcing fiber composite material is improved, which is preferable.

First Bisphenol-Type Epoxy Resin The first bisphenol-type epoxy resin has the function of improving the affinity between the reinforcing fiber bundle and the matrix resin described later and the adhesion after curing when producing the reinforcing fiber bundle.

The first bisphenol-type epoxy resin means a compound in which a bisphenol having two hydroxyphenyl groups or a polymer obtained by polymerizing the bisphenol has two or more epoxy groups. Specific examples of the first bisphenol type epoxy resin are not particularly limited, but bisphenol A type epoxy resin, bisphenol AP type epoxy resin, bisphenol AF type epoxy resin, bisphenol B type epoxy resin, bisphenol BP type epoxy resin, bisphenol C type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol G type epoxy resin, bisphenol M type epoxy resin, bisphenol S type epoxy resin, bisphenol P type epoxy resin, bisphenol PH type epoxy resin, bisphenol TMC type epoxy resins, bisphenol Z-type epoxy resins, and the like.

Also, two or more bisphenols constituting the bisphenol-type epoxy resin may be combined. Examples of such bisphenol-type epoxy resins include mixed-type epoxy resins of bisphenol A and bisphenol E, mixed-type epoxy resins of bisphenol A and bisphenol F, and the like.

Among these, bisphenol A epoxy resin and bisphenol F epoxy resin are preferably used from the viewpoint of further improving the affinity between the reinforcing fiber bundle and the matrix resin described later and the adhesion after curing. It is more preferable to use resin.

In addition, the above-mentioned first bisphenol-type epoxy resin may be used alone or in combination of two or more.

Although the epoxy equivalent weight of the first bisphenol type epoxy resin is not particularly limited, it is preferably 160 to 270 g/equivalent, more preferably 170 to 220 g/equivalent. When the epoxy equivalent of the first bisphenol-type epoxy resin is 160 g/equivalent or more, it is preferable because the emulsification stability of the sizing agent is excellent. On the other hand, when the epoxy equivalent of the first bisphenol-type epoxy resin is 270 g/equivalent or less, the fiber bundling property can be further improved, which is preferable.

The content of the first bisphenol-type epoxy resin in the sizing agent is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, based on the solid mass of the sizing agent. When the content of the first bisphenol-type epoxy resin is 5% by mass or more, it is preferable because the affinity with the matrix resin can be improved. On the other hand, when the content of the first bisphenol-type epoxy resin is 80% by mass or less, co-emulsifiability with the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure can be improved, which is preferable. In addition, in this specification, "the solid content mass of a sizing agent" means the mass of the non-volatile component (solid content) excluding the volatile component of the sizing agent.

Urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure Urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure has an epoxy group, so that it interacts with the surface of the reinforcing fiber (for example, an oxygen-containing functional group, etc.), It has the function of adhering to the surface of reinforcing fibers. Moreover, since it has an alkoxypolyoxyalkylene structure and a urethane bond, it has a function of exhibiting flexibility.

Urethane-modified epoxy resins having an alkoxypolyoxyalkylene structure include, but are not particularly limited to, epoxy resins obtained by reacting compounds having an epoxy group and a hydroxy group, polyisocyanates, and polyoxyalkylene monoalkyl ethers. At this time, a polyol and a chain extender may be further used.

The compound having an epoxy group and a hydroxy group is not particularly limited, but glycidol compounds such as glycidol and methylglycidol; hydroxy groups such as bisphenol A type epoxy resins having a hydroxy group and bisphenol F type epoxy resins having a hydroxy group. bisphenol type epoxy resin; phenol novolak type epoxy resin, ethylphenol novolak type epoxy resin, butylphenol novolak type epoxy resin, octylphenol novolak type epoxy resin, cresol novolak type epoxy resin, ortho cresol novolac type epoxy resin, resorcin novolac type epoxy resin , bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, bisphenol AD novolak type epoxy resin, bisphenol S novolak type epoxy resin, etc., which have hydroxyl groups due to ring-opening of at least part of the epoxy group. . Among these, as a compound having an epoxy group and a hydroxy group, at least one of a bisphenol-type epoxy resin having a hydroxy group and an epoxy group is used because the coherence is improved and a molded product with higher strength is obtained. It is preferable that the moiety has a ring-opened hydroxy group, more preferably a bisphenol A type epoxy resin, a phenol novolac type epoxy resin, or a cresol novolak type epoxy resin having a hydroxy group, and a bisphenol having a hydroxy group. More preferably, it is an A-type epoxy resin. In addition, these compounds having an epoxy group and a hydroxy group may be used alone or in combination of two or more.

The polyisocyanate is not particularly limited, but 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate (tolylene-2,4-diisocyanate (2,4-TDI) ), 1-methyl-2,6-phenylene diisocyanate (tolylene-2,6-diisocyanate (2,6-TDI)), 1-methyl-2,5-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate , 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1 , 4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzene diisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3, 5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2 ,7-diisocyanate, 1,1-dinaphthyl-2,2′-diisocyanate, biphenyl-2,4′-diisocyanate, biphenyl-4,4′-diisocyanate, 3-3′-dimethylbiphenyl-4,4′-diisocyanate , diphenylmethane-4,4′-diisocyanate, diphenylmethane-2,2′-diisocyanate, diphenylmethane-2,4-diisocyanate; tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), dodecamethylene Aliphatic polyisocyanates such as diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate; 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatomethyl) Cyclohexane, 1,4-di(isocyanatomethyl)cyclohexane, isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 3,3' - alicyclic polyisocyanates such as dimethyl-4,4'-dicyclohexylmethane diisocyanate; and trimers thereof.

Among these, aromatic polyisocyanates are preferred, and 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, More preferred are 1-methyl-2,5-phenylene diisocyanate and 1-methyl-3,5-phenylene diisocyanate. In addition, the bisphenol type epoxy resin having the hydroxyl group may be used alone or in combination of two or more.

Examples of the polyoxyalkylene monoalkyl ether include, but are not particularly limited to, compounds represented by the following formulas.

In the above formula, R ¹ represents an alkyl group, A each independently represents an alkylene, and n is an integer of 2 or more.

R ¹ is not particularly limited, but is a methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclobutyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, cyclohexyl group, isohexyl group, n-nonyl group, n-decyl group and the like. Among these, R ¹ is preferably a methyl group, an ethyl group, or a propyl group, more preferably a methyl group, since the storage stability is further improved.

Examples of A include, but are not limited to, methylene, ethylene, propylene, isobutylene, sec-butylene, tert-butylene, pentylene, iso-pentylene, and hexylene. Among these, A is preferably ethylene or propylene, and more preferably ethylene, since storage stability and fiber bundling properties are further improved.

n is an integer of 2 or more, preferably 2-200, more preferably 5-150, still more preferably 5-100.

Among these, it is more preferable to use polyoxyethylene monoalkyl ether, and it is more preferable to use polyoxyethylene monomethyl ether, since storage stability and fiber bundling properties are further improved.

The polyol has two or more hydroxy groups in the molecule, does not have an epoxy group, and has a number average molecular weight of 400 or more. Specific polyols are not particularly limited, but include polyether polyols, polyester polyols, polycarbonate polyols, acrylic polyols, epoxy polyols, natural oil polyols, silicone polyols, fluorine polyols, polyolefin polyols, polyurethane polyols, and the like. These polyols may be used alone or in combination of two or more. In addition, in this specification, the value of the number average molecular weight shall adopt the value measured by the gel permeation chromatography (GPC) which uses polystyrene as a standard substance. At this time, the measurement conditions of the gel permeation chromatography are as follows. That is, using high-speed GPC HLC-8220 (manufactured by Tosoh Corporation), column (TSK-GELGMHXL × 2), 200 mL of a solution of 5 mg of sample dissolved in 10 g of tetrahydrofuran (THF) was injected into the apparatus, flow rate: 1 mL/min (THF), constant temperature bath temperature: 40° C., measured with a differential refraction (RI) detector.

Although the chain extender is not particularly limited, it means one having two or more active hydrogen groups and a number average molecular weight of less than 400. Specific chain extenders are not particularly limited, but (poly)ethylene glycol, (poly)propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2 -butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanediol, cyclohexanedimethanol, bisphenol A, bisphenol B, bisphenol F, bisphenol diols such as S, bisphenol Z, diethylene glycol, trioxyethylene glycol, tetraoxyethylene glycol, pentaoxyethylene glycol, hexaoxyethylene glycol; glycerin, 2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy- 3-hydroxymethylpentane, 1,2,6-hexanetriol, triols such as trimethylolpropane; tetramethylolmethane (pentaerythritol), tetraols such as diglycerin; xylitol, sorbitol, mannitol, allitol, iditol, inositol, diol Polyols having a number average molecular weight of less than 400, such as pentaerythritol and perseitol; Diamines such as cyclohexanediamine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, 1,3-bis(aminomethyl)cyclohexane, hydrazine, tolylenediamine; triamines such as diethylenetriamine; triethylenetetramine, tetraethylenepentamine and the like; Polyamines having a number average molecular weight of less than 400 are included. These chain extenders may be used alone or in combination of two or more.

The structure of the urethane-modified epoxy resin having the above-mentioned alkoxypolyoxyalkylene structure includes the cyanate group of the polyisocyanate, the hydroxy group of the compound having an epoxy group and a hydroxy group, or the hydroxy group of the polyoxyalkylene monoalkyl ether. has a structure in which a urethane bond is formed by the reaction of When the polyisocyanate has 3 or more isocyanate groups, 2 or more of the compound having an epoxy group and a hydroxyl group and/or the polyoxyalkylene monoalkyl ether will react with the polyisocyanate. Moreover, when the compound having an epoxy group and a hydroxy group has two or more hydroxy groups, the two or more hydroxy groups may react with a plurality of polyisocyanates. Furthermore, when using a polyol or a chain extender, a structure such as polyisocyanate-polyol or chain extender-polyisocyanate can be formed, and the molecular structure can be controlled.

The epoxy equivalent of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is preferably 500-2000 g/equivalent, more preferably 1000-1500 g/equivalent. An epoxy equivalent of 500 g/equivalent or more is preferable because emulsifiability can be improved. On the other hand, when the epoxy equivalent is 2000 g/equivalent or less, not only is the fiber bundling property improved and the workability improved, but also the fiber opening property is improved, which is preferable because the composite strength can be improved.

The weight average molecular weight of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is preferably 5,000 to 20,000, more preferably 7,000 to 15,000. A weight-average molecular weight of 5,000 or more is preferable because emulsifiability can be improved. On the other hand, when the weight average molecular weight is 15,000 or less, not only is the fiber bundling property improved and the workability improved, but also the fiber opening property is improved, which is preferable because the composite strength can be improved. In addition, in this specification, the value of "weight average molecular weight" shall adopt the value measured on the same conditions as the above-mentioned number average molecular weight.

The content of the oxyalkylene unit structure derived from the polyoxyalkylene monoalkyl ether, polyol, chain extender, etc. of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is preferably 30% by mass or more, and 40 to 70%. % by mass is more preferred. When the content of the oxyalkylene unit structure is 30% by mass or more, the water dispersibility is further improved, which is preferable.

Further, the content of the single alkoxypolyoxyalkylene unit structure derived from the polyoxyalkylene monoalkyl ether of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is preferably 3 to 60% by mass, more preferably 10 to 55% by mass. % is more preferable.

The method for producing the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is not particularly limited, and it can be synthesized by a known method. At this time, the reaction may be carried out in the presence of a catalyst, or may be carried out without a catalyst.

The content of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure in the sizing agent is preferably 30 to 90% by mass, more preferably 40 to 70% by mass, based on the mass of the solid content of the sizing agent. more preferred. When the content of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is 30% by mass or more, emulsifiability can be improved, which is preferable. On the other hand, when the content of the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure is 90% by mass or less, the affinity of the sizing agent for the matrix resin is improved, which is preferable because the strength of the composite can be improved.

First Other Resin The sizing agent according to the present embodiment may contain the first other resin as long as the effect of the present invention is not impaired.

The first other resin means a polymer compound other than the first bisphenol-type epoxy resin and a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure. In addition, in this specification, a "polymer compound" means a thing with a weight average molecular weight of 300 or more.

Specific examples of the first other resin include novolak type epoxy resins such as phenol novolak type epoxy resin, cresol novolak type epoxy resin, naphthol novolak type epoxy resin; triphenylmethane type epoxy resin; tetraphenylethane type epoxy resin. ; dicyclopentadiene-phenol addition reaction type epoxy resin; phenol aralkyl type epoxy resin; polycarbonate resin; polyphenylene ether resin; polyethylene terephthalate resin; polybutylene terephthalate resin; Resin; polyether sulfone resin; polyketone resin; polyether ketone resin; polyether ether ketone resin; These first other resins may be used alone or in combination of two or more.

The content of the first other resin in the sizing agent is preferably 2 to 30% by mass, more preferably 5 to 20% by mass, based on the mass of the solid content of the sizing agent.

Surfactant The sizing agent according to the present embodiment may contain a surfactant. The surfactant has a function of stably emulsifying and dispersing the sizing agent in a solvent such as water.

The surfactant is not particularly limited, and includes a surfactant having a polyoxyalkylene structure and a surfactant having a sulfonate.

The surfactant having a polyoxyalkylene structure is not particularly limited, but polyoxyalkylene alkyl ether, polyoxyalkylene phenyl ether, polyoxyalkylene alkyl phenyl ether, polyoxyalkylene benzyl phenyl ether, polyoxyalkylene styrylphenyl ether , polyoxyalkylene cumyl phenyl ether, polyoxyalkylene naphthyl phenyl ether, polyoxyalkylene fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, polyethylene glycol and the like. Among these, polyoxyalkylene alkyl ethers, polyoxyalkylene styrylphenyl ethers, and polyoxyethylene-polyoxypropylene block copolymers are preferably used because the mechanical properties of the resulting cured product are further improved. Alkylene alkyl ethers and polyoxyalkylene styrylphenyl ethers are more preferred.

Examples of the polyoxyalkylene alkyl ether include polyoxyethylene such as polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene nonyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene eicosyl ether. Alkyl ether; hexyl ether of polyoxyethylene-polyoxypropylene copolymer, octyl ether of polyoxyethylene-polyoxypropylene copolymer, nonyl ether of polyoxyethylene-polyoxypropylene copolymer, polyoxyethylene-poly Polyoxyethylene-polyoxypropylene copolymer such as lauryl ether of oxypropylene copolymer, stearyl ether of polyoxyethylene-polyoxypropylene copolymer, eicosyl ether of polyoxyethylene-polyoxypropylene copolymer Alkyl ether etc. are mentioned. Among these, it is preferable to use polyoxyalkylene alkyl ether having an alkyl group having 8 to 18 carbon atoms because emulsifiability is improved, such as polyoxyethylene octyl ether, polyoxyethylene nonyl ether, and polyoxyethylene lauryl ether. , more preferably polyoxyethylene stearyl ether.

Examples of the polyoxyalkylene styryl phenyl ether include polyoxyethylene styryl phenyl ether having a styrene addition mole number of 1 to 3, such as polyoxyethylene monostyryl phenyl ether, polyoxyethylene distyryl phenyl ether, and polyoxyethylene tristyryl phenyl ether. , styrylphenyl ether of polyoxyethylene-polyoxypropylene copolymer having 1 to 3 moles of styrene added. Among these, it is preferable to use polyoxyethylene styryl phenyl ether having 1 to 3 moles of styrene added, since it improves emulsifiability.

The weight average molecular weight of the polyoxyethylene-polyoxypropylene block copolymer is preferably 1,000 to 30,000, more preferably 5,000 to 20,000. When the weight average molecular weight of the polyoxyethylene-polyoxypropylene block copolymer is within the above range, emulsifiability is improved, which is preferable.

The content of polyoxyethylene in the polyoxyethylene-polyoxypropylene block copolymer is preferably 40 to 90% by mass, more preferably 50 to 80% by mass.

The sulfonate-containing surfactant has a sulfonate-based hydrophilic portion and a hydrophobic portion.

Specific examples of surfactants having a sulfonate include, but are not limited to, alkylbenzenesulfonates, alkylsulfosuccinates, naphthalenesulfonates, polyoxyethylene alkylphenylsulfonates, and polyoxyethylene alkyldiphenyl ether sulfonates. salts, alkyl diphenyl ether disulfonates, dialkyl succinate sulfonates, and the like. Of these,
Among these, it is preferable to use surfactants having a polyoxyalkylene structure, more preferably polyoxyalkylene alkyl ethers and polyoxyalkylene styrylphenyl ethers, polyoxyethylene having a styrene addition mole number of 1 to 3 It is more preferable to use styryl phenyl ether or polyoxyalkylene alkyl ether, and particularly preferable is polyoxyethylene styryl phenyl ether having 1 to 3 moles of styrene addition.

The content of the surfactant in the sizing agent is preferably 1 to 40% by mass, more preferably 3 to 20% by mass, based on the solid mass of the sizing agent.

Solvent The sizing agent according to the present embodiment may contain a solvent. The solvent may be added intentionally or may remain in the manufacturing process.

Examples of the solvent include, but are not particularly limited to, water; and organic solvents miscible with water.

The organic solvent is not particularly limited, but alcohols such as methanol, ethanol, propanol, isopropyl alcohol and butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethyl acetate, butyl acetate, cellosolve acetate and propylene glycol. Acetic esters such as monomethyl ether acetate, carbitol acetate, ethyl diglycol acetate, propylene glycol monomethyl ether acetate; alcohols such as isopropyl alcohol, butanol, cellosolve, butyl carbitol; aromatic hydrocarbons such as toluene and xylene; Amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like are included. Among these, alcohols and ketones are preferably used as the organic solvent, and butanol, acetone and methyl ethyl ketone are more preferably used. In addition, these organic solvents may be used independently or may be used in combination of 2 or more types.

As the solvent, only water may be used, only an organic solvent may be used, or a mixture of water and an organic solvent may be used. and an organic solvent, and more preferably water.

The content of the solvent is preferably 30 to 95 parts, more preferably 40 to 85 parts, per 100 parts of solid mass of the sizing agent.

(Other sizing agents)
The reinforcing fiber bundles may contain other sizing agents.

Said other sizing agents are other than the sizing agents described above and include other sizing agent materials. In addition, surfactants, solvents and the like may be further included.

The other bundling materials are not particularly limited, but epoxy resins, polyurethane resins, polyacrylic resins, polyester resins, phenol resins, polyamide resins, polyimide resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, polyethersulfone resins, modified polyolefins. (carboxy-modified polyolefin, amino group-modified polyolefin, thiol group-modified polyolefin), modified polyethers (carboxy group-modified polyether, amino group-modified polyether, thiol group-modified polyether) and the like. The other focusing materials mentioned above may be used alone or in combination of two or more.

As for surfactants, solvents, etc., the same sizing agents as described above can be used.

(Structure of reinforcing fiber bundle)
The configuration of the reinforcing fiber bundle may be any configuration.

In one embodiment, a structure obtained by further applying the sizing agent according to the present invention to a reinforcing fiber bundle containing reinforcing fibers and another sizing agent can be employed. For example, a reinforcing fiber bundle obtained by using the sizing agent according to the present invention as it is for a commercially available reinforcing fiber bundle can be used. In this case, at least part of the reinforcing fiber bundles may include a configuration in which reinforcing fibers, another sizing agent, and the sizing agent according to the present invention are laminated in this order.

Further, in another embodiment, a configuration of a reinforcing fiber bundle composed of reinforcing fibers and the sizing agent according to the present invention can also be used. For example, after removing other sizing agents contained in commercially available reinforcing fiber bundles by solvent washing, drying, etc., the sizing agent according to the present invention is used, and carbon fiber bundles that have not been subjected to sizing treatment are used in the present invention. Examples include a form using such a sizing agent, a form using reinforcing fibers and a sizing agent according to the present invention to produce a reinforcing fiber bundle, and the like.

In addition, when the reinforcing fiber bundle contains both the sizing agent according to the present invention and another sizing agent, the total content of both in the reinforcing fiber bundle (total content of the sizing agent) is the total mass of the reinforcing fiber bundle It is preferably 0.1 to 6.0% by mass, more preferably 0.3 to 4.0% by mass. When the total content of the sizing agent is 0.1% by mass or more, it is preferable because it is possible to suppress or prevent fluffing of the reinforcing fiber bundle and improve workability. On the other hand, when the total content of the bundling agent is 6.0% by mass or less, it is possible to prevent or suppress the deterioration of the fiber opening property of the reinforcing fiber bundle, and the strength of the reinforcing fiber composite material is improved, which is preferable.

(Manufacturing method of reinforcing fiber bundle)
A method for manufacturing the reinforcing fiber bundle is not particularly limited, and a known method can be adopted.

In one embodiment, a method for manufacturing a reinforcing fiber bundle includes step (1) of applying a sizing agent coating agent to reinforcing fibers or raw reinforcing fiber bundles and drying the coating agent. In addition, a step (2) of preparing reinforcing fibers, a spinning step (3), and the like may be further included as necessary.

Step (2)
Step (2) is usually performed before step (1). Although the step (2) varies depending on the reinforcing fibers used, a known method can be employed as appropriate.

For example, when the reinforcing fibers are polyacrylonitrile (PAN)-based carbon fibers, the steps for preparing the reinforcing fibers are as follows. That is, first, a polyacrylonitrile-based precursor fiber bundle bundled into a substantially untwisted fiber bundle is subjected to a flameproofing treatment in an oxidizing atmosphere to obtain a flameproof fiber bundle. Then, carbonization treatment is performed in an inert atmosphere to obtain polyacrylonitrile (PAN)-based carbon fibers. After that, an electrolysis treatment in an electrolytic solution and an oxidation treatment in a gas phase or a liquid phase can be performed as appropriate.

Step (1)
Step (1) is a step of applying a sizing agent coating agent to reinforcing fibers or raw reinforcing fiber bundles and drying.

Reinforcing Fibers or Raw Material Reinforcing Fiber Bundles Since the reinforcing fibers described above can be used, the description thereof is omitted here.

The raw material reinforcing fiber bundle may be a reinforcing fiber bundle containing reinforcing fibers and another sizing agent, or may be a reinforcing fiber bundle containing no sizing agent.

The reinforcing fiber bundle containing the reinforcing fibers and other sizing agents may be made into a reinforcing fiber bundle containing no sizing agent by removing the other sizing agents by washing with a solvent, drying, or the like, if necessary.

Sizing Agent Coating Agent The sizing agent coating agent comprises the sizing agent according to the present invention. Specifically, the sizing agent coating agent contains a first bisphenol-type epoxy resin, a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure, and a solvent. In addition, it may further contain a first other resin, a surfactant, and the like.

Descriptions of the first bisphenol-type epoxy resin, the urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure, the first other resin, and the surfactant are omitted here because the above-described ones can be used.

As for the solvent, those mentioned above can also be used. The content of the solvent in the sizing agent coating agent is preferably 10 to 98 parts, more preferably 20 to 90 parts, per 100 parts of the solid mass of the sizing agent.

Attachment Attachment is not particularly limited, and is performed by a known method. For example, a kiss coater method, a roller method, a dipping method, a spray method, a brush, and the like are used.

In addition, other sizing agent coating agents containing other sizing agents can also be used together.

Also, the amount of the sizing agent to be applied can be adjusted by the composition of the sizing agent coating agent, the coating amount, the immersion amount, the spray amount, and the treatment time for each.

Drying Drying is also not particularly limited, and can be carried out by a known method. Examples thereof include natural drying, hot air drying, drying with a hot plate, drying with a roller, and drying with an infrared heater.

Step (3)
Step (3) is usually performed when reinforcing fibers are used in step (1).

The step (3) is not particularly limited, and may be wet spinning, dry spinning, melt spinning, or a combination thereof. As a result, the reinforcing fibers to which the sizing agent is attached can obtain a reinforcing fiber bundle.

[Matrix resin]
The matrix resin contains a second bisphenol-type epoxy resin and an amine curing agent. In addition, it may further contain a phenol compound, a second other resin, another curing agent, a curing accelerator, an organic solvent, an additive, and the like, if necessary.

The viscosity of the matrix resin is not particularly limited, but is preferably 0.1 to 1000 mPa·s, more preferably 0.1 to 500 mPa·s, and further preferably 0.1 to 300 mPa·s. preferable. When the matrix resin has a viscosity of 0.1 mPa·s or more, excessive flow of the matrix resin can be suppressed or prevented when the matrix resin is put into a mold or the like, which is preferable. On the other hand, when the viscosity of the matrix resin is 1000 mPa·s or less, it is preferable because it becomes easy to flow when manufacturing the fiber-reinforced composite material or its cured product, and it is possible to facilitate gas release and easy filling. In this specification, the "viscosity of the matrix resin" means the minimum viscosity measured at 120°C. Moreover, as the value of the "matrix resin viscosity", a value measured by the following method shall be adopted. That is, using DSR-200 (manufactured by Rheometric Scientific FE Co., Ltd.), measurement is performed under the conditions of a frequency of 1 Hz and a parallel plate (25 mmφ, gap of 0.5 mm). The matrix resin is sandwiched between plates heated to 120° C., and the minimum viscosity when the viscosity is measured over time is defined as the viscosity of the matrix resin.

(Second bisphenol type epoxy resin)
Since the second bisphenol-type epoxy resin is the same as the first bisphenol-type epoxy resin described above, the description thereof is omitted here.

The first bisphenol-type epoxy resin and the second bisphenol-type epoxy resin may be the same or different, but it is preferable to use the same resin. That is, in one embodiment, preferably the first bisphenol-type epoxy resin and the second bisphenol-type epoxy resin are the same, and more preferably the first bisphenol-type epoxy resin and the second bisphenol-type epoxy resin are consist of the same

The content of the second bisphenol-type epoxy resin in the matrix resin is preferably 60 to 95% by mass, more preferably 70 to 85% by mass, based on the solid mass of the matrix resin. It is preferable that the content of the second bisphenol type epoxy resin is 60% by mass or more because the strength of the fiber-resin interface can be increased. On the other hand, when the content of the second bisphenol type epoxy resin is 95% by mass or less, the heat resistance can be increased, which is preferable. In this specification, the term "mass of solid content of matrix resin" means the mass of non-volatile components (solid content) excluding volatile components of the matrix resin.

(Second other resin)
The matrix resin according to this embodiment may contain a second other resin within a range that does not impair the effects of the present invention.

The second other resin means a polymer compound other than the second bisphenol type epoxy resin.

The second other resin is not particularly limited, but substantially the same resin as the first other resin can be used. The second other resin may be used alone or in combination of two or more.

The content of the second other resin in the matrix resin is preferably 40% by mass or less, more preferably 30% by mass or less, relative to the solid mass of the matrix resin.

(Amine curing agent)
Amine curing agents have the function of curing epoxy resins. At this time, the epoxy resin includes a first bisphenol-type epoxy resin, an epoxy resin contained in the first other resin, a second bisphenol-type epoxy resin, and an epoxy resin contained in the second other resin. can be Incidentally, the amine curing agent usually has a primary amino group and/or a secondary amino group.

Examples of the amine curing agent include, but are not particularly limited to, chain amine compounds, alicyclic amine compounds, aromatic polyamine compounds, and the like.

Examples of the linear amine compounds include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, diethylenetriamine, dipropylenetriamine, triethylenetetramine (TETA ), tripropylenetetramine, tetraethylenepentamine, hexamethylenediamine, iminobispropylamine, bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, trimethylhexamethylenediamine, polyetherdiamine, diethylaminopropylamine , polyethyleneimine dimer acid ester, dicyandiamide, tetramethylguanidine, adipic acid hydrazide and the like.

Examples of the alicyclic amine compounds include mensenediamine, 1,4-cyclohexanediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane (1,3-BAC), 1,4-bisaminomethylcyclohexane, bis( aminomethyl)norbornane, bis(4-aminocyclohexyl)methane, N-aminoethylpiperazine, diaminodicyclohexylmethane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro (5. 5) Undecane, norbornenediamine, N-methylpiperazine, morpholine, piperidine, piperazine, N-2-aminoethylpiperazine and the like.

Examples of the aromatic polyamine compounds include 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, diamino diethyldiphenylmethane and the like.

Among these, the amine curing agent is preferably an alicyclic amine compound from the viewpoint of further improving mechanical properties such as flexural strength, flexural modulus, tensile strength, and ILSS (Interlaminar Shear Strength). -Bisaminomethylcyclohexane (1,3-BAC), 1,4-bisaminomethylcyclohexane, and isophoronediamine are preferred, and from the viewpoint of high heat resistance, low viscosity, and excellent impregnation into fibers, 1, More preferably, 3-bisaminomethylcyclohexane (1,3-BAC) and 1,4-bisaminomethylcyclohexane are used.

The content of the amine curing agent is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, based on the solid mass of the matrix resin. It is preferable that the content of the amine curing agent is 5% by mass or more because the viscosity before curing can be lowered and the impregnation of the fibers can be enhanced. On the other hand, it is preferable that the content of the amine curing agent is 40% by mass or less because the heat resistance of the resulting cured product can be increased.

(Other curing agents)
The matrix resin may contain other curing agents. The other curing agent means a curing agent other than the amine curing agent.

Other curing agents include, but are not limited to, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, and hexahydrophthalic anhydride. and acid anhydride compounds such as methylhexahydrophthalic anhydride.

The above other curing agents may be used alone or in combination of two or more.

(phenol compound)
The matrix resin may contain a phenolic compound.

The phenol compound has a function of controlling the curing speed, a function of adjusting the viscosity of the matrix resin, and the like.

Specific examples of phenol compounds include phenol; alkylphenol compounds such as cresol, xylenol, ethylphenol, butylphenol, octylphenol, bisphenol A, bisphenol B, bisphenol F, bisphenol S and bisphenol Z; polyhydric phenols such as catechol, resorcinol and hydroquinone. Compound; naphthol compounds such as 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene; tertiary compounds represented by the following formula Examples include phenol compounds having an amino group.

In the above formula, each R ² independently represents an alkyl group, an alkoxy group, a phenyl group, or an aralkyl group, B represents an alkylene, p represents an integer of 1 to 3, and q is an integer of 1 to 5. where the sum of p and q is an integer of 6 or less.

Examples of the alkyl group include, but are not limited to, methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclobutyl group, and the like. is mentioned.

The alkoxy group is not particularly limited, but methoxy group, ethoxy group, propyloxy group, isopropyloxy group, cyclopropyloxy group, n-butoxy group, isobutyloxy group, sec-butyloxy group, tert-butyloxy group, cyclo A butyloxy group and the like can be mentioned.

The aralkyl group is not particularly limited, but is a benzyl group, a phenylethyl group, a phenylpropyl group, a tolylmethyl group, a tolylethyl group, a tolylpropyl group, a xylylmethyl group, a xylylethyl group, a xylylpropyl group, a naphthylmethyl group, and a naphthylethyl group. , a naphthylpropyl group, and the like.

Among these, R ² is preferably an alkyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group.

Examples of B include, but are not limited to, methylene, ethylene, propylene, isobutylene, sec-butylene, tert-butylene, and the like. Among these, methylene and ethylene are preferred, and methylene is more preferred.

The p represents an integer of 1 to 3, preferably 1 or 2, more preferably 1.

q represents an integer of 1 to 5, preferably 1, 2 or 3, more preferably 2 or 3;

Phenolic compounds having such a tertiary amino group include 2-dimethylaminomethylphenol, 4-dimethylaminomethylphenol, 2,4-bis(dimethylaminomethyl)phenol, 2,6-bis(dimethylaminomethyl ) phenol, 2,4,6-tris(dimethylaminomethyl)phenol, 2-dimethylaminoethylphenol, 4-dimethylaminoethylphenol, 2,4-bis(dimethylaminoethyl)phenol, 2,6-bis(dimethyl aminoethyl)phenol, 2,4,6-tris(dimethylaminoethyl)phenol, 4-dimethylaminomethylcatechol, 4-dimethylaminomethylresorcinol and the like.

Among the above, the phenolic compound is preferably a phenolic compound having a tertiary amino group from the viewpoint of further improving mechanical properties such as flexural strength, flexural modulus, tensile strength, and ILSS (Interlaminar Shear Strength). From the viewpoint of increasing the heat resistance of the cured product, 2-dimethylaminomethylphenol, 4-dimethylaminomethylphenol, 2,4-bis(dimethylaminomethyl)phenol, 2,6-bis(dimethylaminomethyl)phenol, 2 ,4,6-tris(dimethylaminomethyl)phenol is more preferable, and from the viewpoint that the heat resistance of the cured product is high and the curability can be accelerated, 2,4,6-tris(dimethylaminomethyl) Phenol is more preferred.

In addition, the above-mentioned phenol compounds may be used alone or in combination of two or more.

The content of the phenol compound is preferably 0.5 to 10.0% by mass, more preferably 0.5 to 5.0% by mass, based on the solid mass of the matrix resin. It is preferable that the content of the phenol compound is 0.5% by mass or more because the curability can be accelerated. On the other hand, when the content of the phenol compound is 10.0% by mass or less, it is preferable because the heat resistance of the cured product can be increased.

(Curing accelerator)
The matrix resin may contain a curing accelerator.

Examples of the curing accelerator include, but are not limited to, tertiary amine compounds or salts thereof having no phenolic hydroxyl group, such as diazabicycloundecene (DBU) and diazabicyclononene (DBN); 2-methylimidazole; , 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate and other imidazole compounds; triphenylphosphine, tetraphenylphosphonium tetraphenylborate and other phosphine compounds; 3-phenyl-1,1 -dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 2,4-bis( urea compounds such as 3,3-dimethylureido)toluene; These curing accelerators may be used alone or in combination of two or more.

The amount of the curing accelerator added is preferably 0.01 to 5.0% by mass, more preferably 0.5 to 3.0% by mass, based on the solid mass of the matrix resin.

(organic solvent)
The matrix resin may contain an organic solvent. The organic solvent has a function of adjusting the viscosity of the matrix resin.

The organic solvent is not particularly limited, but alcohols such as methanol, ethanol, propanol, isopropyl alcohol and butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl Acetic esters such as ether acetate, carbitol acetate, ethyl diglycol acetate, propylene glycol monomethyl ether acetate; alcohols such as isopropyl alcohol, butanol, cellosolve, butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethyl Amides such as formamide, dimethylacetamide, N-methylpyrrolidone, and the like are included. These organic solvents may be used alone or in combination of two or more.

The content of the solvent in the matrix resin is preferably 70 parts or less, more preferably 45 parts or less, per 100 parts of the matrix resin mass of the sizing agent.

(Additive)
The matrix resin may contain additives.

The additives are not particularly limited, but flame retardants such as phosphorus flame retardants, nitrogen flame retardants, silicone flame retardants, inorganic flame retardants, and organic metal salt flame retardants; titanium oxide, glass flakes, and calcium carbonate. , barium sulfate, silica, fillers such as silicon nitride; plasticizers; antioxidants; UV absorbers; light stabilizers; hydrolysis inhibitor; lubricant; impact imparting agent; slidability improver; compatibilizer; nucleating agent; thickening agent; anti-settling agent; anti-sagging agent; anti-foaming agent; coupling agent; These additives may be used alone or in combination of two or more.

(Manufacturing method of matrix resin)
The method for producing the matrix resin is not particularly limited, and it can be produced by a known method. For example, the matrix resin can be produced by adding an amine curing agent to the second bisphenol type epoxy resin, and then, if necessary, adding a phenol compound or the like.

[Form of fiber-reinforced composite material]
The fiber-reinforced composite material contains the reinforcing fiber bundles and matrix resin described above. That is, the fiber-reinforced composite material is included in the first bisphenol-type epoxy resin, the second bisphenol-type epoxy resin, the first other resin, the second other resin, etc. contained in the reinforcing fiber bundle and the matrix resin. The thermosetting resin has an uncured form.

Specific forms of the fiber-reinforced composite material include a sheet-like form (prepreg) in which a reinforcing fiber bundle is impregnated with a matrix resin, a particulate form (pellet), a liquid mixture form, and the like.

When the fiber-reinforced composite material is in the form of a prepreg, the reinforcing fiber bundle may be in the form of a UD (UniDirection) material in which the fiber direction is aligned in one direction, or in the form of a woven material woven vertically and horizontally. may be in the form The form of the woven material may be plain weave, twill weave, satin weave, or the like. Also, two or more prepregs may be laminated. At this time, the number of layers to be laminated, the direction of lamination, etc. are not particularly limited. These forms are appropriately selected according to desired performance and the like.

In addition, when the form of the fiber-reinforced composite material is a pellet, the shape is not particularly limited, and is spherical, elliptical, cylindrical, polygonal columnar, needle-like, rod-like, plate-like, disc-like, flaky, It may be scale-like, amorphous, or the like.

<Cured product>
According to one aspect of the present invention, a cured product is provided. The cured product is obtained by curing a fiber-reinforced composite material. At this time, the cured product has a form in which the thermosetting resin that may be included in the fiber-reinforced composite material is cured. In addition, when the thermosetting resin is not cured, it corresponds to a fiber-reinforced composite material. Here, in the present specification, "curing of the fiber-reinforced composite material" means a state in which no curing heat is observed when differential scanning calorimetry (DSC) is performed.

The cured product may have any form. For example, it may have a form obtained by simply curing a fiber-reinforced composite material, or the obtained cured product may be further subjected to secondary molding.

The resulting cured product has excellent mechanical properties and is therefore used in a variety of applications, such as automobiles, aircraft, ships, railways and other transportation fields; wind power generation, pressure vessels, fuel cells, solar cells, secondary batteries, and offshore oil fields. Energy fields such as; Building materials, bridge structures, underground structures, marine structures, etc. civil engineering and construction fields; Robot arms, rolls, machine parts, etc. industrial machinery fields; Cases, display devices, semiconductors, electromagnetic wave absorption materials , IC trays, condensers, capacitors, heat sources, etc.; medical fields, such as medical equipment and instruments; golf shafts, golf heads, fishing gear, yachts, cruisers, boats, tennis rackets, badminton rackets, baseball bats , bicycles, etc., in the field of sports and leisure. Among others, it can be applied particularly favorably to the field of transport equipment, which requires high mechanical properties.

<Method for producing fiber-reinforced composite material and cured product>
A method for producing a fiber-reinforced composite material is not particularly limited, but includes a step of impregnating a reinforcing fiber bundle with a matrix resin.

The impregnation method is not particularly limited. For example, the matrix resin may be brought into contact with the reinforcing fiber bundle, or the reinforcing fiber bundle may be brought into contact with the matrix resin. Specifically, a method of arranging reinforcing fiber bundles in a predetermined array in a mold or the like and pouring a matrix resin into this, a method of immersing the reinforcing fiber bundles in the matrix resin, and the like can be mentioned.

Additional steps may be included depending on the form of the resulting fiber-reinforced composite material. For example, when the form of the fiber-reinforced composite material is a prepreg, the step of laminating the prepregs may be further included.

A method for producing a cured product includes a step of curing the fiber-reinforced composite material.

At this time, the curing temperature is preferably 60 to 180°C, more preferably 80 to 140°C. A curing temperature of 60° C. or higher is preferable because the curing completion time can be shortened. On the other hand, when the curing temperature is 180° C. or lower, it is preferable because energy consumption during production can be suppressed.

Further, the curing may be performed in two steps of preliminary curing and main curing. In this case, the pre-curing temperature is preferably 40 to 100°C, more preferably 50 to 80°C. Further, the temperature for main curing is preferably 60 to 180°C, more preferably 80 to 140°C.

The curing time is preferably 1 to 120 minutes, more preferably 1 to 30 minutes. A curing time of 1 minute or more is preferable because sufficient time can be obtained for the reinforcing fiber bundles to be impregnated with the matrix resin in the RTM method or the like, which will be described later. On the other hand, if the curing time is 120 minutes or less, it is preferable because production efficiency is improved.

The method for producing a cured product may further include additional steps as necessary. For example, it may further include a step of secondary molding. Examples of the secondary molding include cutting such as machining, water jet processing and laser processing; joining such as adhesion and welding.

In a preferred embodiment, methods for producing fiber-reinforced composite materials and/or cured products include hand lay-up, spray-up, sheet molding (SMC), filament winding, resin transfer molding (RTM), and vacuum impregnation method (VaRTM). , an autoclave method, and the like.

The hand lay-up is a method in which fibers are set in a mold, resin is applied with a roller or brush, defoamed while being impregnated, and cured.

The spray-up is a method in which fibers and resin are sprayed onto a mold from a spray gun, deaerated while being impregnated with a roller or brush, and cured.

The sheet molding (SMC) is a method in which a fiber-reinforced composite material in which fibers are impregnated with resin is sandwiched between films, passed through a roller to form a continuous sheet, cut, stacked in a mold, and heated and pressurized with a press. be.

The filament winding is a method in which fibers are impregnated by passing them through a resin bath containing a matrix resin, and the fiber composite material is wound around a rotating mold and then cured by heating.

The resin transfer molding (RTM) is a method in which a concave mold in which a fiber intermediate is set is sealed with a convex mold, a resin is injected, impregnated under pressure, and cured.

The vacuum impregnation method (VaRTM) is a method in which a reinforcing fiber bundle laminated on a mold is sealed in a plastic film or the like, vacuum-sucked, and then a matrix resin is injected, impregnated, and cured.

In the autoclave method, a reinforcing fiber bundle is impregnated with a matrix resin and semi-cured prepreg is laminated in a mold, the entire laminated surface is covered with a plastic film or the like, airtightly sealed and bagged, and the product is autoclaved while being degassed under reduced pressure. In this method, the material is placed in a (heating and pressurizing pot) and heated and pressurized to harden.

Among these, resin transfer molding (RTM), vacuum impregnation method (Va-RTM), and filament winding are preferred, and resin transfer molding (RTM) is more preferred, from the viewpoint of mass productivity and low cost.

EXAMPLES The present invention will be described below using examples, but the present invention is not limited to the description of the examples. In addition, although the indication of "parts" is used in the examples, "parts by mass" is indicated unless otherwise specified.

[Synthesis Example 1]
(Synthesis of urethane-modified epoxy resin having alkoxypolyoxyalkylene structure)
A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device was charged with Epiclon 1050, a compound having an epoxy group and a hydroxy group (bisphenol A type epoxy resin having a hydroxy group, epoxy equivalent: 477 g/ equivalent, manufactured by DIC Corporation) 52 parts, Uniox M-550 (polyoxyethylene monomethyl ether, hydroxyl value: 100, manufactured by NOF Corporation) 65 parts, which is a polyoxyalkylene monoalkyl ether, and 34 parts of methyl ethyl ketone was added and thoroughly stirred and dissolved at 40°C. Then, 20 parts of tolylene diisocyanate, which is a polyisocyanate, was added at 40° C. and reacted at 60 to 65° C. for 6 hours to synthesize a urethane-modified epoxy resin having a methoxypolyoxyethylene structure.

The weight average molecular weight of the obtained urethane-modified epoxy resin having a methoxypolyoxyethylene structure was measured by the following method. That is, it was measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. Specifically, a high-speed GPC HLC-8220 (manufactured by Tosoh Corporation) and a column (TSK-GELGMHXL×2) were used, and 200 mL of a solution of 5 mg of a sample dissolved in 10 g of tetrahydrofuran (THF) was injected into the apparatus. , flow rate: 1 mL/min (THF), constant temperature bath temperature: 40° C., measured with a differential refraction (RI) detector. As a result, the weight average molecular weight of the urethane-modified epoxy resin having a methoxypolyoxyethylene structure was 11,000.

(Preparation of sizing agent coating agent)
137 parts of Epiclon 840 (bisphenol A type epoxy resin, epoxy equivalent: 190 g/equivalent, manufactured by DIC Corporation), which is the first bisphenol type epoxy resin, is added to the urethane-modified epoxy resin having a methoxypolyoxyethylene structure synthesized above; and 27 parts of Emulgen A-500 (polyoxyethylene distyrenated phenyl ether, manufactured by Kao Corporation) as a surfactant were added and sufficiently stirred.

Then, 920 parts of ion-exchanged water was added dropwise over 30 minutes, followed by stirring and mixing for 15 minutes. The obtained aqueous dispersion was concentrated by distillation under reduced pressure to prepare 1000 parts of a sizing agent coating agent having a non-volatile content of 30% by mass.

[Synthesis Example 2]
(Synthesis of urethane-modified epoxy resin having alkoxypolyoxyalkylene structure)
Synthesis Example 1 except that the amount of Epiclon 1050 added was changed to 73 parts, the amount of Uniox M-550 added to 92 parts, the amount of methyl ethyl ketone added to 48 parts, and the amount of tolylene diisocyanate added to 28 parts. A urethane-modified epoxy resin having a methoxypolyoxyethylene structure was synthesized in a similar manner. In addition, when the weight average molecular weight was measured in the same manner as in Synthesis Example 1, it was 11,500.

(Preparation of sizing agent coating agent)
In the urethane-modified epoxy resin having a methoxypolyoxyethylene structure synthesized above, 97 parts of Epiclon 840, another resin Epiclon N-740-80M (phenol novolak type epoxy resin, epoxy equivalent: 190 g / equivalent, DIC stock Company) 121 parts and Emulgen A-500 29 parts were added and thoroughly stirred.

Next, 1000 parts of a sizing agent coating agent having a non-volatile content of 30% by mass was prepared in the same manner as in Synthesis Example 1, except that 1190 parts of ion-exchanged water was used.

[Synthesis Example 3]
(Synthesis of urethane-modified epoxy resin having alkoxypolyoxyalkylene structure)
A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a dropping device was charged with 45 parts of polyol polyethylene glycol (number average molecular weight: 330, hydroxyl value: 187) and 36 parts of methyl ethyl ketone. The mixture was thoroughly stirred and dissolved at ℃. Then, 26 parts of tolylene diisocyanate was added at 40° C. and reacted at 60-65° C. for 4 hours. Next, 54 parts of Epiclon 1050 and 17 parts of polyethylene glycol monomethyl ether (hydroxyl value: 102), which is a polyoxyalkylene monoalkyl ether, are added and reacted at 60 to 65°C for 4 hours to form a methoxypolyoxyethylene structure. A urethane-modified epoxy resin having In addition, when the weight average molecular weight was measured in the same manner as in Synthesis Example 1, it was 12,000.

(Preparation of sizing agent coating agent)
140 parts of Epiclon 830 (bisphenol F type epoxy resin, epoxy equivalent: 190 g/equivalent, manufactured by DIC Corporation), which is the first bisphenol type epoxy resin, to the urethane-modified epoxy resin having a methoxypolyoxyethylene structure synthesized above; and 14 parts of Emulgen A-500 were added and thoroughly stirred.

Next, 1000 parts of a sizing agent coating agent having a non-volatile content of 30% by mass was prepared in the same manner as in Synthesis Example 1, except that 900 parts of ion-exchanged water was used.

[Synthesis Example 4]
(Synthesis of urethane-modified epoxy resin having alkoxypolyoxyalkylene structure)
Synthesis Example 1 except that the amount of Epiclon 1050 added was changed to 55 parts, the amount of Uniox M-550 added to 120 parts, the amount of methyl ethyl ketone added to 36 parts, and the amount of tolylene diisocyanate added to 20 parts. A urethane-modified epoxy resin having a methoxypolyoxyethylene structure was synthesized in a similar manner. In addition, when the weight average molecular weight was measured in the same manner as in Synthesis Example 1, it was 10,500.

(Preparation of sizing agent coating agent)
1000 parts of a sizing agent coating agent having a non-volatile content of 30% by mass was prepared in the same manner as in Synthesis Example 1, except that Epiclon 840 was not added and the amount of ion-exchanged water used was changed to 970 parts.

[Synthesis Example 5]
(Synthesis of urethane-modified epoxy resin having alkoxypolyoxyalkylene structure)
A urethane-modified epoxy resin having a methoxypolyoxyethylene structure was synthesized in the same manner as in Synthesis Example 3. In addition, when the weight average molecular weight was measured in the same manner as in Synthesis Example 1, it was 12,000.

(Preparation of sizing agent coating agent)
1200 parts of a sizing agent coating agent having a non-volatile content of 30% by mass was prepared in the same manner as in Synthesis Example 1, except that Epiclon 840 was not added and the amount of ion-exchanged water used was changed to 900 parts.

[Synthesis Example 6]
(Preparation of sizing agent coating agent)
330 parts of Epiclon 840 and 33 parts of Emulgen A-500 were added and thoroughly stirred. 920 parts of ion-exchanged water was added dropwise over 30 minutes, and the mixture was further stirred and mixed for 15 minutes. The obtained aqueous dispersion was concentrated by distillation under reduced pressure to prepare 1000 parts of a sizing agent coating agent having a non-volatile content of 30% by mass.

The compositions of the sizing agent coating agents produced in Synthesis Examples 1 to 6 are shown in Table 1 below.

[Example 1]
[Production of reinforcing fiber bundle]
Polyacrylonitrile-based carbon fiber (single yarn diameter: 7 μm, strand strength: 4,400 MPa, elastic modulus: 235 GPa) 6000 no-size yarns were bundled, and the sizing agent coating agent (non-volatile content: 30 mass %) was diluted with ion-exchanged water to a non-volatile content of 5% by mass, and impregnated by an immersion method. Next, the adhered amount of the active ingredient was adjusted to 1% by mass by squeezing with a roller, and a reinforcing fiber bundle surface-treated with a fiber sizing agent was obtained by heat-treating at 150° C. for 30 minutes.

(Preparation of matrix resin)
Epiclon 850 (bisphenol A type epoxy resin, epoxy equivalent: 188 g/equivalent, manufactured by DIC Corporation), which is the second bisphenol type epoxy resin, is added to 1,3-bisaminomethylcyclohexane (1,3-bisaminomethylcyclohexane (1, 3-BAC, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 18.9 parts and 2 parts of Ancamine K-54 (2,4,6-tris (dimethylaminomethyl) phenol, manufactured by Evonik Co., Ltd.), which is a phenol compound, at 25 ° C. A matrix resin was prepared by mixing and stirring.

(Manufacture of fiber reinforced composite materials and cured products)
A reinforcing fiber sheet was produced by alternately laminating nine reinforcing fiber bundles prepared above in a mold such that the fiber directions are 0° and 90°. Next, the matrix resin prepared above was injected into a mold and treated at 130° C. for 10 minutes to produce a cured product having a thickness of 2 mm. The carbon fiber weight content was 65%.

[Example 2]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the phenol compound was changed to p-tert-butylphenol (PTBP, manufactured by DIC Corporation).

[Example 3]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the amine compound was changed to triethylenetetramine (TETA, manufactured by Tosoh Corporation) and the amount added was 12.9 parts. bottom.

[Example 4]
The second bisphenol type epoxy resin was changed to Epiclon 830-S (bisphenol F type epoxy resin, epoxy equivalent: 170 g/equivalent, manufactured by DIC Corporation), and the amount of 1,3-BAC added was changed to 20.9 parts. A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except for the changes.

[Example 5]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the sizing agent coating agent was changed to that prepared in Synthesis Example 2.

[Example 6]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 5, except that the amine compound was changed to TETA and the amount added was 12.9 parts.

[Example 7]
The sizing agent coating agent was changed to that prepared in Synthesis Example 3, the second bisphenol type epoxy resin was changed to Epiclon 830-S, the amine compound was changed to TETA, and the amount added was 14.3 parts. A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1 except for.

[Example 8]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 7, except that the amine compound was changed to 1,3-BAC and the amount added was 20.9 parts.

[Comparative Example 1]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the sizing agent coating agent was changed to that prepared in Synthesis Example 4.

[Comparative Example 2]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the sizing agent coating agent was changed to that prepared in Synthesis Example 5.

[Comparative Example 3]
A fiber-reinforced composite material and a cured product were produced in the same manner as in Example 1, except that the sizing agent coating agent was changed to that prepared in Synthesis Example 6.

The compositions of the fiber-reinforced composite materials produced in Examples 1-8 and Comparative Examples 1-3 are shown in Table 1 below.

[Evaluation of cured product]
The cured products produced in Examples 1-8 and Comparative Examples 1-3 were evaluated.

(Bending strength, bending elastic modulus)
Using a precision universal testing machine (manufactured by Shimadzu Corporation), the measurement was carried out according to the method of JIS K7074:1998. The results obtained are shown in Table 3 below.

(Tensile strength)
Using a precision universal testing machine (manufactured by Shimadzu Corporation), measurements were carried out according to the method of JIS K7165:2008. The results obtained are shown in Table 3 below.

(ILSS)
Using a precision universal testing machine (manufactured by Shimadzu Corporation), the measurement was carried out according to the method of JIS K7078:1991. The results obtained are shown in Table 3 below.

The results in Table 3 show that the cured products obtained in Examples 1-8 have better mechanical properties than the cured products obtained in Comparative Examples 1-3.

Claims (4)

A fiber-reinforced composite material comprising a reinforcing fiber bundle having reinforcing fibers and a sizing agent, and a matrix resin,
The sizing agent contains a first bisphenol-type epoxy resin and a urethane-modified epoxy resin having an alkoxypolyoxyalkylene structure,
The matrix resin comprises a second bisphenol-type epoxy resin, an amine curing agent having a primary amino group and/or a secondary amino group, and a phenolic compound, and the phenolic compound comprises phenol, cresol, xylenol, ethyl phenol, butylphenol, octylphenol, bisphenol A, bisphenol B, bisphenol F, bisphenol S, bisphenol Z, catechol, resorcinol, hydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2, A fiber-reinforced composite material which is at least one selected from 6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and a phenolic compound having a tertiary amino group represented by the following formula.

In the above formula, each R ² independently represents an alkyl group, an alkoxy group, a phenyl group, or an aralkyl group, B represents an alkylene, p represents an integer of 1 to 3, and q is an integer of 1 to 5. where the sum of p and q is an integer of 6 or less. 2. The fiber-reinforced composite material of claim 1, wherein said first bisphenol-type epoxy resin and said second bisphenol-type epoxy resin comprise the same. The fiber-reinforced composite material according to claim 1 or 2, wherein the phenolic compound is a phenolic compound having a tertiary amino group. A cured product obtained by curing the fiber-reinforced composite material according to any one of claims 1 to 3.