JP2017048481A - Sizing agent coated reinforced fiber, manufacturing method of sizing agent coated reinforced fiber, prepreg and fiber reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sizing agent coated reinforced fiber which lets a fiber reinforced composite material exhibit high level toughness by using a sizing agent high in safety, a manufacturing method of the sizing agent coated reinforced fiber and the fiber reinforced composite material using the reinforced fiber.SOLUTION: A sizing agent coated reinforced fiber is obtained by coating a sizing agent containing at least polyrotaxane (A) and a surfactant (B) in a reinforced fiber and having mass ratio (B)/(A) of (B) to (A) of 0.1 to 1.5.SELECTED DRAWING: None

Description

  The present invention relates to a sizing agent-coated reinforcing fiber, a sizing agent-coated reinforcing fiber manufacturing method, a prepreg, and a fiber-reinforced composite material, which constitute a fiber-reinforced composite material having excellent adhesive strength with a matrix resin and high mechanical strength. is there.

  Because it is lightweight and has excellent strength, rigidity, dimensional stability, etc., fiber reinforced composite materials are widely used in general industrial fields such as office equipment, computer applications (IC trays, notebook PC cases, etc.), and automobile applications. The demand is increasing year by year. As these reinforcing fibers, metal fibers such as aluminum fibers and stainless fibers, organic fibers such as aramid fibers and PBO fibers, inorganic fibers such as silicon carbide fibers, and carbon fibers are used. Carbon fiber is suitable from the viewpoint of the balance of specific strength, specific rigidity and lightness, and among them, polyacrylonitrile-based carbon fiber is suitably used.

  As a sizing agent applied to such reinforcing fibers, phenol resins, melamine resins, bismaleimide resins, unsaturated polyester resins, epoxy resins, and the like are suitably used. In general, in a fiber reinforced composite material molded article composed of reinforcing fibers and a matrix resin, high interfacial adhesion is required between the reinforcing fibers and the matrix resin in order to develop high tensile strength and compressive strength in the fiber direction. Therefore, as a sizing agent to be applied to the reinforcing fiber, an epoxy resin is particularly preferably used for the purpose of increasing such interfacial adhesion and providing a fiber-reinforced composite material having a high mechanical strength. For example, a method of applying diglycidyl ether of bisphenol A as a sizing agent to carbon fibers has been proposed (Patent Documents 1 and 2). In addition, a method of applying an epoxy adduct of polyalkylene glycol to a carbon fiber as a sizing agent has been proposed (Patent Documents 3, 4, and 5).

Examples of the method of applying the sizing agent to the reinforcing fiber include a method of immersing the reinforcing fiber in a sizing agent-containing liquid via a roller, and the solvent of the sizing agent-containing liquid is an organic solvent or a solvent from the viewpoint of solubility. Water is used. (Patent Document 1)
By the way, since the fiber reinforced composite material is a heterogeneous material, there is a large difference between the physical properties in the arrangement direction of the reinforcing fibers and the physical properties in other directions. For example, it is known that the impact resistance indicated by resistance to falling weight impact is governed by delamination strength, that is, interlayer toughness such as G _Ic (opening mode) and G _IIc (in-plane shear mode). In particular, a carbon fiber reinforced composite material using a thermosetting resin as a matrix resin reflects the low toughness of the matrix resin and has the property of being easily destroyed by stresses from other than the direction of the carbon fibers that are reinforcing fibers. Yes.

  Therefore, in order to solve such problems, a sizing agent that can improve the strength against stress from other than the fiber arrangement direction in addition to the improvement in tensile strength and compressive strength in the fiber direction has been studied. For example, there is a method of obtaining a carbon fiber reinforced composite material method having excellent interlayer toughness by using a sizing agent containing an epoxy resin which is incompatible with a flexible epoxy resin and the flexible epoxy resin as an essential component. It has been proposed (Patent Document 6).

U.S. Pat. No. 3,957,716 JP-A-57-171767 JP-A-57-128266 US Pat. No. 4,555,446 JP-A-62-33872 International Publication WO 07/060833

  However, the above method is not always sufficient in view of further demands for further weight reduction and high interlaminar toughness, which will increase further in the future. With the progress of increasing toughness and strength of matrix resins, development of a sizing agent that can further enhance the interlaminar toughness of fiber reinforced composite materials is desired. Further, the sizing agent is required to reduce the amount of organic solvent used in order to reduce the environmental load.

  An object of the present invention is to provide a sizing agent-coated reinforcing fiber that exhibits a high degree of toughness in a fiber-reinforced composite material using a highly safe sizing agent in view of the above-described problems in the prior art, and production of the sizing agent-coated reinforcing fiber It is to provide a method and a fiber-reinforced composite material using the reinforcing fiber.

  The present inventors improve the toughness of a fiber-reinforced composite material using the reinforcing fiber by applying a sizing agent containing at least a specific ratio of polyrotaxane (A) and surfactant (B) to the reinforcing fiber. The inventors have found that this is possible and have come up with the present invention.

  That is, the present invention includes at least a polyrotaxane (A) and a surfactant (B) in the reinforcing fiber, and the mass ratio (B) / (A) of (A) and (B) is 0.1 to 1.5. A sizing agent-coated reinforcing fiber formed by applying a sizing agent. Here, the polyrotaxane (A) is a cyclic molecule, a linear molecule included in a skewered manner in the cyclic molecule, and both ends of the linear molecule so that the cyclic molecule is not detached from the linear molecule. It has a blocking group arranged in.

  The present invention also includes a sizing agent that contains at least the polyrotaxane (A) and the surfactant (B), and the mass ratio (B) / (A) of (A) to (B) is 0.1 to 1.5. The manufacturing method of the sizing agent application | coating reinforcement fiber which apply | coats a containing liquid to a reinforcement fiber is included.

  Moreover, this invention contains the prepreg which consists of a reinforced fiber and thermosetting resin which apply | coated said sizing agent.

  Moreover, this invention contains the fiber reinforced composite material formed by hardening said prepreg.

  Moreover, this invention contains the fiber reinforced composite material which consists of said sizing agent application | coating reinforcement fiber and a thermosetting resin.

  Since the sizing agent-coated reinforcing fiber of the present invention is formed using a highly safe sizing agent, the handleability is good, and the fiber-reinforced composite material obtained by using the sizing agent-coated reinforcing fiber is High toughness.

  Hereinafter, embodiments of the present invention will be described.

  The present invention includes at least a polyrotaxane (A) and a surfactant (B) in a reinforcing fiber, and a sizing agent having a mass ratio (B) / (A) of (A) and (B) of 0.1 to 1.5. Is a reinforcing fiber coated with a sizing agent.

  First, the sizing agent used in the present invention will be described.

  The sizing agent used in the present invention needs to contain a polyrotaxane (A). The polyrotaxane (A) is a compound having a structure in which blocking groups are arranged so that the cyclic molecules are not detached at both ends of the pseudopolyrotaxane in which the openings of the cyclic molecules are clasped by the linear molecules. It is. Since the polyrotaxane (A) has specific functions and properties, application in various technical fields has been studied in recent years. For example, Japanese Patent Laid-Open No. 2008-1997 proposes a technique for improving the stretchability, washing resistance, wrinkle resistance and the like of a fiber material using a polyrotaxane material.

  In the present invention, the sizing agent containing at least the polyrotaxane (A) and the surfactant (B) is provided with a liquid containing the sizing agent (referred to as a sizing agent-containing liquid) to the reinforcing fiber, so that high elongation and high toughness These properties can be imparted to the reinforcing fiber / matrix resin interface. It has been found that a fiber-reinforced composite material having a high degree of toughness can be provided at the time of interlaminar fracture of the fiber-reinforced composite material obtained thereby. Below, each structure of the polyrotaxane (A) contained in the sizing agent of this invention, and surfactant (B) are demonstrated.

[Polyrotaxane (A)]
<Cyclic molecule>
The cyclic molecule used in the polyrotaxane (A) is not particularly limited as long as it is a molecule in which a linear molecule can be included in a skewered manner in the opening.

  As the cyclic molecule, a cyclic molecule having a hydroxyl group is preferable, and cyclodextrin is more preferable from the viewpoint of inclusion property and productivity. Here, the cyclodextrin may be a cyclodextrin derivative. The type of cyclodextrin or cyclodextrin derivative is not particularly limited, but is preferably selected from α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and derivatives thereof. Here, the cyclodextrin derivative is introduced by substituting a polymer chain and / or a substituent on the hydroxyl group of cyclodextrin. The dispersibility of polyrotaxane (A) in the sizing agent is adjusted by appropriately selecting these polymer chains and / or substituents according to the other components of the sizing agent and the solvent in which the sizing agent is dissolved. can do. Examples of such a polymer chain include polyethylene glycol, polypropylene glycol, polyethylene, polypropylene, polyvinyl alcohol, polyacrylic acid ester, polylactone, and polylactam. On the other hand, examples of the substituent include a hydroxyl group, thionyl group, amino group, sulfonyl group, phosphonyl group, acetyl group, methyl group, ethyl group, propyl group, isopropyl group and other alkyl groups, trityl group, tosyl group, and trimethyl. A silane group, a phenyl group, etc. are mentioned. Generally, when the other component of the sizing agent or the solvent in which the sizing agent is dissolved is a hydrophilic compound, it is preferable to introduce a hydrophilic polymer chain or a substituent. In addition, when the other component of the sizing agent or the solvent in which the sizing agent is dissolved is a hydrophobic compound, it is preferable to introduce a hydrophobic polymer chain or a substituent. Improve the affinity of the polyrotaxane (A) to the sizing agent by introducing a polymer chain or a substituent, impart good dispersibility in the sizing agent, and firmly bond the sizing agent and the reinforcing fiber surface. Can do.

  From such a viewpoint, it is more preferable that the cyclodextrin is modified with a polymer chain. The polymer chain preferably includes a bond selected from an —O— bond and an —NH— bond, and a group selected from an alkylene group and an alkenylene group. Here, the alkylene group preferably has 1 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. The alkenylene group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of such polymer chains include polyalkylene glycol, polyalkenylene glycol, polyalkyleneimine, polylactone, polylactam and the like. Preferable specific examples include polyethylene glycol, polypropylene glycol, polyethyleneimine, poly β-propiolactone, poly δ-valerolactone, poly ε-caprolactone, poly ε-caprolactam, polylauryl lactam and the like. Further, a part of hydrogen of the alkylene or alkenylene group is substituted with at least one selected from the group consisting of an acyl group such as a hydroxyl group, a carboxyl group and an acetyl group, an olefin group such as a phenyl group, a halogen atom and an allyl group. It may be.

  More specific examples of such cyclodextrins or cyclodextrin derivatives include α-cyclodextrin (glucose number = 6, pore inner diameter = about 0.45-0.6 μm), β-cyclodextrin (glucose). Number = 7, pore inner diameter = about 0.6 to 0.8 μm), γ-cyclodextrin (glucose number = 8, pore inner diameter = about 0.8 to 0.95 μm), dimethylcyclodextrin, Glucosyl cyclodextrin, 2-hydroxypropyl-α-cyclodextrin, 2,6-di-O-methyl-α-cyclodextrin, 6-O-α-maltosyl-α-cyclodextrin, 6-O-α-D- Glucosyl-α-cyclodextrin, hexakis (2,3,6-tri-O-acetyl) -α-cyclodextrin, hexakis (2,3,6 Tri-O-methyl) -α-cyclodextrin, hexakis (6-O-tosyl) -α-cyclodextrin, hexakis (6-amino-6-deoxy) -α-cyclodextrin, hexakis (2,3-acetyl- 6-bromo-6-deoxy) -α-cyclodextrin, hexakis (2,3,6-tri-O-octyl) -α-cyclodextrin, mono (2-O-phosphoryl) -α-cyclodextrin, mono [ 2, (3) -O- (carboxylmethyl)]-α-cyclodextrin, octakis (6-Ot-butyldimethylsilyl) -α-cyclodextrin, succinyl-α-cyclodextrin, glucuronylglucosyl-β -Cyclodextrin, heptakis (2,6-di-O-methyl) -β-cyclodextrin, heptakis (2, -Di-O-ethyl) -β-cyclodextrin, heptakis (6-O-sulfo) -β-cyclodextrin, heptakis (2,3-di-O-acetyl-6-O-sulfo) -β-cyclodextrin , Heptakis (2,3-di-O-methyl-6-O-sulfo) -β-cyclodextrin, heptakis (2,3,6-tri-O-acetyl) -β-cyclodextrin, heptakis (2,3 , 6-Tri-O-benzoyl) -β-cyclodextrin, heptakis (2,3,6-tri-O-methyl) -β-cyclodextrin, heptakis (3-O-acetyl-2,6-di-O -Methyl)-[beta] -cyclodextrin, heptakis (2,3-O-acetyl-6-bromo-6-deoxy)-[beta] -cyclodextrin, 2-hydroxyethyl- [beta] -cyclodext , Hydroxypropyl-β-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, (2-hydroxy-3-N, N, N-trimethylamino) propyl-β-cyclodextrin, 6-O-α-maltosyl -Β-cyclodextrin, methyl-β-cyclodextrin, hexakis (6-amino-6-deoxy) -β-cyclodextrin, bis (6-azido-6-deoxy) -β-cyclodextrin, mono (2-O -Phosphoryl) -β-cyclodextrin, hexakis [6-deoxy-6- (1-imidazolyl)]-β-cyclodextrin, monoacetyl-β-cyclodextrin, triacetyl-β-cyclodextrin, monochlorotriazinyl- β-cyclodextrin, 6-O-α-D-glucosyl-β-cycl Dextrin, 6-O-α-D-maltosyl-β-cyclodextrin, succinyl-β-cyclodextrin, succinyl- (2-hydroxypropyl) -β-cyclodextrin, 2-carboxymethyl-β-cyclodextrin, 2- Carboxyethyl-β-cyclodextrin, butyl-β-cyclodextrin, sulfopropyl-β-cyclodextrin, 6-monodeoxy-6-monoamino-β-cyclodextrin, silyl [(6-Ot-butyldimethyl) 2 , 3-Di-O-acetyl] -β-cyclodextrin, 2-hydroxyethyl-γ-cyclodextrin, 2-hydroxypropyl-γ-cyclodextrin, butyl-γ-cyclodextrin, 3A-amino-3A-deoxy- (2AS, 3AS) -γ-cyclodextri Mono-2-O- (p-toluenesulfonyl) -γ-cyclodextrin, mono-6-O- (p-toluenesulfonyl) -γ-cyclodextrin, mono-6-O-mesitylenesulfonyl-γ-cyclodextrin , Octakis (2,3,6-tri-O-methyl) -γ-cyclodextrin, octakis (2,6-di-O-phenyl) -γ-cyclodextrin, octakis (6-Ot-butyldimethylsilyl) ) -Γ-cyclodextrin, octakis (2,3,6-tri-O-acetyl) -γ-cyclodextrin, and the like. Here, the above-mentioned cyclic molecules such as cyclodextrin can be used singly or in combination of two or more.

<Linear molecule>
The linear molecule of the polyrotaxane (A) is not particularly limited as long as it can be included in a skewered manner in the opening of the cyclic molecule.

  For example, as linear molecules, polyvinyl alcohol, polyvinyl pyrrolidone, poly (meth) acrylic acid, cellulose resins (carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), polyacrylamide, polyethylene glycol, polypropylene glycol, polyvinyl acetal resins , Polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch, and copolymers thereof; polyolefin resins such as polyethylene and polypropylene; polyester resins; polyvinyl chloride resins; polystyrene, acrylonitrile-styrene copolymer resins, etc. Polystyrene resin; polymethyl methacrylate, (meth) acrylic acid ester copolymer, acrylonitrile-methyl acrylate Acrylic resins such as relate copolymer resins; Polycarbonate resins; Polyurethane resins; Vinyl chloride-vinyl acetate copolymer resins; Polyvinyl butyral resins; Polyisobutylene; Polytetrahydrofuran; Polyaniline; Acrylonitrile-butadiene-styrene copolymers (ABS resins) Polyamides such as nylon, polyimides, polydienes such as polyisoprene and polybutadiene, polysiloxanes such as polydimethylsiloxane, polysulfones, polyimines, polyacetic anhydrides, polyureas, polysulfides, and polyphosphazenes Polyketones; polyphenylenes; polyhaloolefins; and derivatives of these resins. In particular, from the viewpoint of good dispersibility in a sizing agent and productivity, polyethylene glycol, polyisoprene, polyisobutylene, polybutadiene, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene, polypropylene, polyvinyl alcohol and A linear molecule selected from the group consisting of polyvinyl methyl ether is preferred, and polyethylene glycol is particularly preferred.

  The linear molecule of the polyrotaxane (A) preferably has a weight average molecular weight of 15,000 or more, more preferably 17,000 or more. Moreover, it is preferable that a weight average molecular weight is 30,000 or less, and it is more preferable that it is 25,000 or less. The weight average molecular weight is determined based on the retention time (retention capacity) of standard polystyrene having a known molecular weight measured under the same conditions as the retention time (retention capacity) measured using a gel permeation chromatograph (GPC). It can be calculated in terms of molecular weight. When the weight average molecular weight of the linear molecule is 15,000 or more, when the sizing-coated reinforcing fiber is used as a matrix resin and a composite material, the polyrotaxane (A) is produced by the cyclic molecule sliding on the linear molecule. The slide ring effect is particularly excellent, and the physical properties of the fiber-reinforced composite material are particularly improved. When the weight average molecular weight of the linear molecule is 30,000 or less, the interaction between the polyrotaxane (A) and the matrix resin is optimized, and the physical properties of the fiber-reinforced composite material are particularly improved.

<Inclusion amount>
When a plurality of cyclic molecules include a linear molecule in a skewered manner, when the amount of cyclic molecules included in a single linear molecule is 1 as the maximum, the cyclic molecule is 0.001 to 0. .6, preferably 0.01 to 0.5, more preferably 0.05 to 0.4.

  The maximum inclusion amount of the cyclic molecule can be calculated from the length of the linear molecule and the thickness of the cyclic molecule. For example, when the linear molecule is polyethylene glycol and the cyclic molecule is an α-cyclodextrin molecule, the maximum inclusion amount is experimentally determined (see Macromolecules 1993, 26, 5698-5703). The contents of this document are all incorporated herein.

<Blocking group>
The blocking group of the polyrotaxane (A) is not particularly limited as long as it is a group that is arranged at both ends of the linear molecule and acts so that the cyclic molecule is not eliminated.

  For example, the group consisting of dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, substituted benzenes, optionally substituted polynuclear aromatics, and steroids as blocking groups A group selected from is preferred. Examples of the substituent include alkyl groups such as methyl groups, alkyloxy groups such as methoxy groups, hydroxy groups, halogen groups, cyano groups, sulfonyl groups, carboxyl groups, amino groups, and phenyl groups. It is not limited to these. One or more substituents may be present. The blocking group is more preferably a group selected from the group consisting of dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, and pyrenes, more preferably an adamantane group or a trityl group. is there.

  Among these polyrotaxanes (A), a cyclic molecule is an α-cyclodextrin derivative having a polymer chain containing ε-caprolactone as a monomer unit, and a polyrotaxane (A) whose linear molecule is polyethylene glycol is sizing. Particularly preferred from the viewpoint of good dispersibility in the agent and industrial productivity. Specific examples of such compound products include “Celum®” superpolymer SH1310P, “Celum®” superpolymer SH2400P, “Celum®” superpolymer SH3400P (all of which are advanced soft materials). Etc.). Among these, “Celum (registered trademark)” superpolymer SH2400P whose linear molecule is polyethylene glycol having a weight average molecular weight of 20,000 can be preferably used.

  In addition to the polyrotaxane (A), the sizing agent can contain a compound that promotes cross-linking of the molecules of the polyrotaxane (A). Examples of the compound that promotes crosslinking include a compound having a plurality of reactive groups that react with an active group of the cyclic molecule of polyrotaxane (A). That is, the plurality of reactive groups are cross-linked by reacting with an active group with a plurality of polyrotaxanes (A) to form chemical bonds.

  Examples of the reactive group include an isocyanate group, a thioisocyanate group, an oxirane group, an oxetane group, a carbodiimide group, a silanol group, an oxazoline group, and an aziridine group. An isocyanate group or a thioisocyanate group is more preferable, and an isocyanate group is more preferable.

  More specific examples of the compound having a plurality of the above reactive groups include polyether, polyester, polysiloxane, polycarbonate, poly (meth) acrylate, polyene or copolymers thereof, or both ends of the above reaction. Mention may be made of compounds modified by groups.

  A product in which the polyrotaxane (A) and a compound that promotes crosslinking are mixed is also commercially available. Specific examples of such products include "Celum (registered trademark)" elastomer SH3400S, "Celum (registered trademark)" elastomer SH3400M, and "Celum (registered trademark)" elastomer SH3400H (all manufactured by Advanced Soft Materials Co., Ltd.). ) And the like.

[Surfactant (B)]
The surfactant (B) is an essential component for imparting the polyrotaxane (A) to the reinforcing fiber as a constituent component of the sizing agent-containing liquid. Examples of the surfactant (B) include nonionic, cationic and anionic surfactants.

  Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene fatty acid amide ether, polyhydric alcohol fatty acid ester, polyoxyethylene polyhydric alcohol fatty acid. Examples thereof include esters, fatty acid sucrose esters, alkylolamides, and polyoxyalkylene block copolymers.

  The cationic surfactant refers to a surfactant having a cationic hydrophilic group. Specific examples of the cationic surfactant include lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, and alkylbenzyldimethylammonium chloride.

  An anionic surfactant refers to a surfactant having an anionic hydrophilic group. Specific examples of the anionic surfactant include sodium alkyl sulfate, sodium alkylbenzene sulfate, sodium alkyldiphenyl ether sulfate and the like.

  In the sizing agent of the present invention, it is essential that the mass ratio (B) / (A) of the polyrotaxane (A) and the surfactant (B) is 0.1 to 1.5. When (B) / (A) is less than 0.1, there are few surfactants coordinated to the polyrotaxane molecule, and good water dispersibility cannot be obtained. When (B) / (A) is larger than 1.5, the surplus surfactant (B) that does not contribute to the dispersion of the polyrotaxane (A) adversely affects the physical properties of the fiber-reinforced composite material. From the viewpoint of dispersibility and physical properties of the fiber-reinforced composite material, (B) / (A) is more preferably 0.3 to 1.3.

  It is preferable that the surfactant (B) contains at least a nonionic surfactant. Since the nonionic surfactant does not have an electric charge and does not affect the reactivity of the matrix resin of the fiber reinforced composite material, it does not easily affect the physical properties of the fiber reinforced composite material.

  Furthermore, the surfactant (B) preferably contains a nonionic surfactant having an HLB value of less than 10. The nonionic surfactant has a nonionic hydrophilic group and a hydrophobic group, and has an HLB value as an index of hydrophilicity and hydrophobicity. The HLB value is represented by a number between 0 and 20, and the closer to 0, the higher the hydrophobicity, and the closer to 20, the higher the hydrophilicity. The reason is not clear, but the polyrotaxane (A) having a hydrophilic group coordinates with a highly hydrophobic surfactant having an HLB value of less than 10, thereby suppressing aggregation between polyrotaxane molecules due to hydrophilic interaction. Therefore, it is considered that good water dispersibility can be obtained.

  Furthermore, it is preferable that the surfactant (B) contains at least a nonionic surfactant having an HLB value of less than 10 and a surfactant having an HLB value of 10 or more. Although the reason is not clear, a highly hydrophobic surfactant having a HLB value of less than 10 is coordinated to the polyrotaxane (A) having a hydrophilic group, and a polyrotaxane (A) having a high hydrophilicity having an HLB value of 10 or more By coordinating, it is considered that the hydrophobic interaction between the surfactants can be suppressed and good water dispersibility can be obtained.

  The sizing agent preferably further contains a compound having an epoxy group in addition to the polyrotaxane (A) and the surfactant (B). The epoxy group interacts with the surface functional group of the reinforcing fiber to improve adhesion with the surface of the reinforcing fiber, and has high interaction and reactivity with the matrix resin, particularly the epoxy resin. Thereby, while having high interlaminar fracture toughness, the fiber reinforced composite material excellent in the adhesiveness of a reinforced fiber and matrix resin can be obtained.

  The compound having an epoxy may be an aliphatic epoxy compound or an aromatic epoxy compound. These compounds can be used alone or in combination of two or more. Specific examples of the compound having an epoxy include a glycidyl ether type epoxy compound derived from a polyol, a glycidyl amine type epoxy compound derived from an amine having a plurality of active hydrogens, a glycidyl ester type epoxy compound derived from a polycarboxylic acid, And an epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule.

  Examples of the glycidyl ether type epoxy compound include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetrabromobisphenol A, phenol novolac, cresol novolac, hydroquinone, resorcinol, 4,4′-dihydroxy-3,3 ′, 5. , 5'-tetramethylbiphenyl, 1,6-dihydroxynaphthalene, 9,9-bis (4-hydroxyphenyl) fluorene, tris (p-hydroxyphenyl) methane, and tetrakis (p-hydroxyphenyl) ethane and epichlorohydride Examples include glycidyl ether type epoxy compounds obtained by reaction with phosphorus. Also, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, trimethylene glycol, polybutylene glycol, 1,2-butanediol 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, hydrogenated Bisphenol A, hydrogenated bisphenol F, glycerin, diglycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol, and arabito If, glycidyl ether type epoxy compound obtained by the reaction of epichlorohydrin. Examples of the epoxy compound include a glycidyl ether type epoxy compound having a dicyclopentadiene skeleton and a glycidyl ether type epoxy compound having a biphenylaralkyl skeleton.

  Examples of the glycidylamine type epoxy compound include N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, 1,3-bis (aminomethyl) cyclohexane, m-xylenediamine, m-phenylenediamine, 4 4,4'-diaminodiphenylmethane and 9,9-bis (4-aminophenyl) fluorene. Furthermore, for example, epoxy compounds obtained by reacting both hydroxyl groups and amino groups of aminophenols of m-aminophenol, p-aminophenol, and 4-amino-3-methylphenol with epichlorohydrin are mentioned. It is done.

  Examples of the glycidyl ester type epoxy compound include glycidyl ester type epoxy compounds obtained by reacting phthalic acid, terephthalic acid, hexahydrophthalic acid, and dimer acid with epichlorohydrin.

  Examples of the epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule include an epoxy compound having an epoxycyclohexane ring in the molecule and epoxidized soybean oil.

  In addition to these epoxy compounds, epoxy compounds such as triglycidyl isocyanurate can be mentioned. Furthermore, the epoxy compound synthesize | combined from the epoxy compound mentioned above as a raw material, for example, the epoxy compound synthesize | combined by oxazolidone ring formation reaction from bisphenol A diglycidyl ether and tolylene diisocyanate, etc. are mentioned.

  Furthermore, an epoxy compound having one or more epoxy groups and one or more functional groups selected from an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, and a sulfo group is used as the epoxy compound. You can also.

  Examples of the compound having an epoxy group and an amide group include glycidyl benzamide and an amide-modified epoxy compound. The amide-modified epoxy compound can be obtained by reacting an epoxy group of an epoxy compound having two or more epoxy groups with a carboxyl group of a dicarboxylic acid amide.

  Examples of the compound having an epoxy group and an imide group include glycidyl phthalimide. Specific examples include “Denacol (registered trademark)” EX-731 (manufactured by Nagase ChemteX Corporation).

  Examples of the compound having an epoxy group and a urethane group include a urethane-modified epoxy compound. Specifically, “Adeka Resin (registered trademark)” EPU-78-13S, EPU-6, EPU-11, EPU-15, EPU-16A, EPU-16N, EPU-17T-6, EPU-1348 and EPU-1395 (Made by ADEKA Corporation). Alternatively, the terminal hydroxyl group of polyethylene oxide monoalkyl ether is reacted with a polyvalent isocyanate compound having a reaction equivalent to the amount of the hydroxyl group, and then the isocyanate residue of the obtained reaction product is reacted with the hydroxyl group in the polyvalent epoxy compound. The compound obtained by is mentioned. Here, as the polyvalent isocyanate compound used, 2,4-tolylene diisocyanate, metaphenylene diisocyanate, paraphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, triphenylmethane triisocyanate and biphenyl-2 4,4′-triisocyanate and the like.

  Examples of the compound having an epoxy group and a urea group include a urea-modified epoxy compound. The urea-modified epoxy compound can be obtained by reacting the epoxy group of an epoxy compound having two or more epoxy groups with the carboxyl group of the dicarboxylic acid urea.

  Examples of the compound having an epoxy group and a sulfonyl group include a bisphenol S-type epoxy compound.

  Examples of the compound having an epoxy group and a sulfo group include a p-toluenesulfonic acid glycidyl compound and a 3-nitrobenzenesulfonic acid glycidyl compound.

  The epoxy value of the compound having an epoxy is preferably 2.0 meq / g or more. When the epoxy value of the epoxy compound is 2.0 meq / g or more, an interaction with the carbon fiber is formed at a high density, and the adhesion between the carbon fiber and the matrix resin is further improved. The upper limit of the epoxy value is not particularly limited, but 8.0 meq / g is sufficient from the viewpoint of adhesiveness because the interaction with the reinforcing fiber is reinforced. The epoxy value of the epoxy compound is more preferably 3.0 to 7.0 meq / g.

  Among the compounds described above, the compound having an epoxy group is preferably a compound selected from a polyether-type polyepoxy compound and a polyol-type polyepoxy compound having two or more epoxy groups in the molecule from the viewpoint of high adhesiveness. As the number of epoxy groups increases, the adhesion is further strengthened by increasing the interaction with the functional groups on the surface of the reinforcing fiber. Furthermore, by having a group selected from a hydroxyl group and an ether bond in the molecule, the interaction with the functional group on the surface of the reinforcing fiber is strengthened, so that the physical properties of the obtained fiber-reinforced composite material are improved. There is no upper limit to the number of epoxy groups, but 10 is sufficient from the viewpoint of adhesiveness.

  The compound having an epoxy is a glycidyl ether type epoxy obtained by reaction of at least one compound selected from glycerin, diglycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol, and arabitol with epichlorohydrin. More preferably, it is a compound. Since these compounds have flexible molecular chains, the interaction with the functional group on the surface of the reinforcing fiber is further increased, and the physical properties of the fiber-reinforced composite material are further improved.

  Specific examples of products of these compounds include polyglycerin polyglycidyl ether (for example, “Denacol (registered trademark)” EX-512, EX-521 manufactured by Nagase ChemteX Corporation), trimethylolpropane polyglycidyl ether (for example, "Denacol (registered trademark) EX-321" manufactured by Nagase ChemteX Corporation, glycerin polyglycidyl ether (for example, "Denacol (registered trademark)" EX-313, EX-314 manufactured by Nagase ChemteX Corporation) ), Sorbitol polyglycidyl ether (for example, “Denacol (registered trademark)” EX-611, EX-612, EX-614, EX-614B, EX-622 manufactured by Nagase ChemteX Corporation), pentaerythritol polyglycidyl ether (For example, manufactured by Nagase ChemteX Corporation "Denacol (registered trademark)" EX-411), and the like. These compounds can be used alone or in combination of two or more.

  Moreover, it is preferable that the content ratio of the polyrotaxane (A) in a sizing agent is 5 mass% or more with respect to the sizing agent whole quantity, More preferably, it is 10 mass% or more, More preferably, it is 15 mass% or more. When the content ratio of the polyrotaxane (A) is 5% by mass or more, the high elongation and high toughness properties of the polyrotaxane (A) are more effectively expressed when the fiber reinforced composite material is used. Moreover, it is preferable that the content ratio of a polyrotaxane (A) is 50 mass% or less with respect to the total amount of a sizing agent, More preferably, it is 40 mass% or less. When the content ratio of the polyrotaxane (A) is 50% by mass or less, the plasticity of the polyrotaxane (A) acts appropriately on the matrix resin, and the tensile strength of the fiber-reinforced composite material tends to be higher.

  Moreover, it is preferable that the compound which has an epoxy group in a sizing agent is contained 5 mass% or more with respect to the sizing agent whole quantity, More preferably, it is 30 mass% or more, More preferably, it is 50 mass% or more. Moreover, it is preferable that the compound which has an epoxy group in a sizing agent is contained in the ratio of 90 mass% or less with respect to the sizing agent whole quantity, More preferably, it is 85 mass% or less, More preferably, it is 80 mass% or less. .

  The polyrotaxane (A), the surfactant (B) and the compound having an epoxy group in the sizing agent in the present invention can be eluted by immersing the sizing agent-coated reinforcing fiber in a solvent and performing ultrasonic cleaning. As the solvent, for example, acetone, N, N-dimethylformamide, acetonitrile, dichloromethane, chloroform or a mixture thereof can be preferably used. The ratio of the polyrotaxane (A) and the compound having an epoxy group in the sizing agent is determined by gas chromatography, liquid chromatography, nuclear magnetic resonance spectroscopy (NMR), oxidation-reduction titration method, acid-base using this eluate. It can be determined by a titration method or the like.

  Further, the sizing agent may contain components other than those described above. For example, auxiliary components such as an adhesion promoting component that enhances the adhesion between the sizing agent and the reinforcing fibers and / or the matrix resin can be added.

  Examples of the adhesion promoting component include triisopropylamine, dibutylethanolamine, diethylethanolamine, triisopropanolamine, diisopropylethylamine, N-benzylimidazole, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU). ), 1,5-diazabicyclo [4,3,0] -5-nonene (DBN), 1,4-diazabicyclo [2,2,2] octane, 5,6-dibutylamino-1,8-diaza-bicyclo Tertiary amine compounds such as [5,4,0] undecene-7 (DBA) and salts thereof; phosphine compounds such as tributylphosphine and triphenylphosphine; and quaternary phosphonium salts. These compounds are preferably added in an amount of 1 to 25% by mass, more preferably 2 to 8% by mass, based on the total amount of the sizing agent.

  Furthermore, you may add a polyester compound, an unsaturated polyester compound, etc. suitably in the range which does not affect the effect of this invention.

  Furthermore, as long as the effect of the present invention is not affected, a component that imparts convergence or flexibility to the sizing agent-coated reinforcing fiber may be appropriately added. Thereby, the handleability, abrasion resistance and fluff resistance of the sizing agent-coated reinforcing fiber can be improved, and the impregnation property of the matrix resin can be improved.

  Reinforcing fibers include carbon fibers, glass fibers, ceramic fibers, silicon carbide fibers and other inorganic fibers; aromatic polyamide fibers (aramid fibers), polyethylene fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene naphthalate fibers, poly Various organic fibers such as arylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber, and polyketone fiber can be exemplified, but are not limited thereto. Of these, inorganic fibers such as carbon fibers and glass fibers, and aromatic polyamide fibers are preferable, and carbon fibers are more preferable. Particularly preferred are polyacrylonitrile-based carbon fibers which have good specific strength and specific elastic modulus, and can provide a lightweight and high-strength fiber-reinforced composite material.

  Next, the manufacturing method of polyacrylonitrile-type carbon fiber is demonstrated.

  As a spinning method for obtaining a carbon fiber precursor fiber, spinning methods such as wet, dry, and dry-wet can be used. From the viewpoint of easily obtaining high-strength carbon fibers, it is preferable to use a wet or dry wet spinning method.

  The total fineness of the carbon fibers is preferably 400 to 3000 tex. Moreover, the number of filaments of carbon fiber is preferably 1000 to 100,000, and more preferably 3000 to 50000. In order to further improve the adhesion between the carbon fibers and the matrix resin, it is preferable to apply the above sizing agent to carbon fibers having a surface roughness (Ra) of 6.0 to 100 nm. In order to obtain a carbon fiber having a surface roughness (Ra) of 6.0 to 100 nm, it is preferable to spin the precursor fiber by a wet spinning method.

  In the wet spinning method, a solution obtained by dissolving a polyacrylonitrile homopolymer or copolymer in a solvent can be used as the spinning dope. As the solvent, an organic solvent such as dimethyl sulfoxide, dimethylformamide, or dimethylacetamide, or an aqueous solution of an inorganic compound such as nitric acid, sodium rhodanate, zinc chloride, or sodium thiocyanate is used. Dimethyl sulfoxide or dimethylacetamide is preferred as the solvent.

  The above spinning solution is spun through a die and discharged into a spinning bath to be solidified. As the spinning bath, an aqueous solution of a solvent used as a solvent for the spinning dope can be used. A spinning solution containing the same solvent as the spinning solution is preferably used, and a dimethyl sulfoxide aqueous solution or a dimethylacetamide aqueous solution is preferable. The fibers solidified in the spinning bath are washed with water and drawn to obtain precursor fibers. The obtained precursor fiber is subjected to flameproofing treatment and carbonization treatment, and if necessary, further subjected to graphitization treatment to obtain carbon fiber. As conditions for the carbonization treatment and graphitization treatment, the maximum heat treatment temperature is preferably 1100 ° C. or higher, more preferably 1300 to 3000 ° C.

  From the viewpoint of obtaining carbon fibers having high strength and elastic modulus, carbon fibers having fineness are preferably used. Specifically, the single fiber diameter of the carbon fiber is preferably 7.5 μm or less, more preferably 6 μm or less, and further preferably 5.5 μm or less. The lower limit of the single fiber diameter is not particularly limited, but if it is less than 4.5 μm, the single fiber is likely to be cut in the process, and the productivity may be lowered.

  The carbon fiber is usually subjected to an oxidation treatment in order to improve adhesion with the matrix resin, and oxygen-containing functional groups are introduced to the surface. As the oxidation treatment method, gas phase oxidation, liquid phase oxidation and liquid phase electrolytic oxidation are used. From the viewpoint of high productivity and uniform processing, liquid phase electrolytic oxidation is preferably used.

  Examples of the electrolytic solution used in the liquid phase electrolytic oxidation include an acidic electrolytic solution and an alkaline electrolytic solution. Examples of the acidic electrolyte include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid, and carbonic acid; organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid, and maleic acid; or ammonium sulfate and ammonium hydrogen sulfate. And the like. Of these, sulfuric acid and nitric acid exhibiting strong acidity are preferably used. Specific examples of the alkaline electrolyte include aqueous solutions of hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide; sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, Aqueous solutions of carbonates such as barium carbonate and ammonium carbonate; aqueous solutions of bicarbonates such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate and ammonium bicarbonate; ammonia, tetraalkylammonium hydroxide And an aqueous solution of hydrazine. Among these, from the viewpoint of not containing an alkali metal that causes curing inhibition of the matrix resin, an aqueous solution of ammonium carbonate and ammonium hydrogen carbonate or an aqueous solution of tetraalkylammonium hydroxide exhibiting strong alkalinity is preferably used.

  From the viewpoint that the covalent bond formation between the sizing agent component and the oxygen-containing functional group on the surface of the carbon fiber is promoted and the adhesion is further improved, after the carbon fiber is electrolytically oxidized with an alkaline electrolytic solution, or the carbon fiber is an acidic aqueous solution It is preferable to apply a sizing agent after electrolytic oxidation treatment in the substrate, followed by washing with an alkaline aqueous solution. When carbon fiber is subjected to electrolytic oxidation treatment, an excessively oxidized part on the surface of the carbon fiber exists as a fragile layer and may become a starting point of destruction when made into a composite material. It is considered preferable to dissolve and remove with an aqueous solution.

  The pH of the alkaline aqueous solution used for washing is preferably in the range of 7 to 14, and more preferably in the range of 10 to 14. Specific examples of the alkaline aqueous solution include aqueous solutions of hydroxides such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide; sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, and barium carbonate. And aqueous solutions of carbonates such as ammonium carbonate; aqueous solutions of bicarbonates such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate and ammonium bicarbonate; ammonia, tetraalkylammonium hydroxide and hydrazine An aqueous solution of Among these, from the viewpoint of not containing an alkali metal that causes curing inhibition of the matrix resin, an aqueous solution of ammonium carbonate or ammonium hydrogen carbonate, or an aqueous solution of tetraalkylammonium hydroxide exhibiting strong alkalinity is preferably used. As a method for washing the carbon fiber with an alkaline aqueous solution, for example, a dip method and a spray method can be used. Among these, from the viewpoint of easy cleaning, it is preferable to use the dip method, and it is more preferable to use the dip method while vibrating the carbon fiber with ultrasonic waves.

  The concentration of the electrolytic solution is preferably within a range of 0.01 to 5 mol / liter, and more preferably within a range of 0.1 to 1 mol / liter. When the concentration of the electrolytic solution is 0.01 mol / liter or more, the voltage of the electrolytic oxidation treatment is lowered, which is advantageous in terms of operating cost. On the other hand, when the concentration of the electrolytic solution is 5 mol / liter or less, it is advantageous from the viewpoint of safety.

  The temperature of the electrolytic solution is preferably in the range of 10 to 100 ° C, more preferably in the range of 10 to 40 ° C. When the temperature of the electrolytic solution is 10 ° C. or higher, the efficiency of the electrolytic oxidation treatment is improved, which is advantageous in terms of operating cost. On the other hand, when the temperature of the electrolytic solution is 100 ° C. or lower, it is advantageous from the viewpoint of safety.

The current density in the liquid phase electrolytic oxidation is preferably in the range of surface area 1 m ² per 1.5 to 1000 amps / ^{m 2} of carbon fiber in the electrolyte solution, more preferably from 3 to 500 amps / ^{m 2} Is within. When the current density is 1.5 amperes / m ² or more, the efficiency of the electrolytic oxidation treatment is improved, which is advantageous in terms of operating cost. On the other hand, when the current density is 1000 amperes / m ² or less, it is advantageous from the viewpoint of safety.

  The amount of electricity in the liquid phase electrolytic oxidation treatment is preferably optimized according to the carbonization degree of the carbon fiber. When processing high-modulus carbon fiber, a larger amount of electricity is required.

  The carbon fiber has a surface oxygen concentration (O / C) which is a ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface as measured by X-ray photoelectron spectroscopy of 0.05 to 0.00. Those within the range of 50 are preferred, more preferably within the range of 0.07 to 0.30, and even more preferably within the range of 0.10 to 0.30. When the surface oxygen concentration (O / C) is 0.05 or more, an oxygen-containing functional group on the surface of the carbon fiber can be secured and strong adhesion with the matrix resin can be obtained. Moreover, when the surface oxygen concentration (O / C) is 0.5 or less, a decrease in strength of the carbon fiber itself due to oxidation can be suppressed.

The surface oxygen concentration of the carbon fiber can be determined by X-ray photoelectron spectroscopy according to the following procedure. First, carbon fibers from which dirt and the like adhering to the carbon fiber surface were removed with a solvent were cut into a length of 20 mm, spread and arranged on a copper sample support, and then AlKα1 and 2 were used as an X-ray source. The sample chamber is kept at 1 × 10 ⁻⁸ Torr. As a correction value for the peak accompanying charging during measurement, the binding energy value of the main peak (peak top) of C _1s is adjusted to 284.6 eV. The C _1s peak area is obtained by drawing a straight base line in the range of 282 to 296 eV. The O _1s peak area is obtained by drawing a straight base line in the range of 528 to 540 eV. Here, the surface oxygen concentration can be calculated as an atomic ratio by using a sensitivity correction value unique to the apparatus from the ratio of the O _1s peak area to the C _1s peak area.

  The carbon fibers are preferably washed with a liquid phase electrolytic oxidation treatment or an alkaline aqueous solution, then washed with water and dried. In this case, if the drying temperature is too high, the functional groups present on the outermost surface of the carbon fiber are likely to disappear due to thermal decomposition, and thus it is desirable to dry at the lowest possible temperature. Specifically, the drying is performed at a drying temperature of preferably 250 ° C. or lower, more preferably 210 ° C. or lower. On the other hand, considering the efficiency of drying, the drying temperature is preferably 110 ° C. or higher, and more preferably 140 ° C. or higher.

  As described above, carbon fibers that are preferably used can be obtained.

  The strand strength of the carbon fiber is preferably 3.5 GPa or more, more preferably 4 GPa or more, and further preferably 5 GPa. Moreover, it is preferable that the strand elastic modulus of carbon fiber is 220 GPa or more, More preferably, it is 240 GPa or more, More preferably, it is 280 GPa or more. In addition, the strand tensile strength and strand elastic modulus of a carbon fiber bundle can be calculated | required by the resin impregnation strand test method of JIS-R-7608 (2004).

  Next, a method for producing the sizing coated reinforcing fiber of the present invention will be described.

  A sizing agent containing at least a polyrotaxane (A) and a surfactant (B) can be diluted with a solvent and used. Examples of such a solvent include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Among these, water and dimethylformamide are preferably used because of easy handling and advantageous from the viewpoint of safety, and water is particularly preferably used.

  The sizing agent-containing liquid in the present invention contains at least a polyrotaxane (A) and a surfactant (B), and the mass ratio (B) / (A) of (A) and (B) is 0.1 to 1.5. An aqueous emulsion obtained by emulsifying as a composition is preferred. At this time, an aqueous emulsion can be prepared by mixing at least the polyrotaxane (A) and the surfactant (B) in a uniform state and adding water little by little. The prepared aqueous emulsion may contain an epoxy group-containing compound and other stabilizing components.

  The dispersion stability of the aqueous emulsion can be judged from the amount of precipitate after standing after preparation of the aqueous emulsion. If the precipitate weight relative to the initial amount is small, it can be determined that the dispersion has sufficient dispersion stability.

  The concentration of the sizing agent in the sizing agent-containing liquid is usually preferably in the range of 0.2 to 20% by mass.

  An aqueous emulsion comprising at least a polyrotaxane (A) and a surfactant (B) and emulsified as a composition having a mass ratio (B) / (A) of (A) and (B) of 0.1 to 1.5. The particle size measured by the particle size distribution meter is preferably 100 to 600 nanometers. More preferably, it is 500 nanometers or less, More preferably, it is the range of 300 nanometers or less. Within the above range, the dispersibility in water is good, and the long-term stability of the sizing agent is improved. Further, the sizing agent can be uniformly applied when the sizing agent is applied to the carbon fibers.

  Next, means for applying the sizing agent to the reinforcing fibers will be described. As a coating method, at least a polyrotaxane (A), a surfactant (B), and a sizing agent-containing solution in which other sizing agent components are dissolved or dispersed at the same time are applied at once, and each component is arbitrarily selected. A method of applying the sizing agent-containing solution dissolved or dispersed individually a plurality of times is preferably used. In this case, the polyrotaxane (A), the surfactant (B) and other components can be applied in any order. The coating means for the case where the above sizing agent dispersion contains the polyrotaxane (A), the surfactant (B) and other components at the same time will be described below. The polyrotaxane (A) and the surfactant (B) are described below. The same can be done when each of the sizing agent-containing liquid containing and the sizing agent-containing liquid containing other components is applied separately.

  Examples of the application means include, for example, a method in which reinforcing fibers are immersed in a sizing agent-containing liquid via a roller, a method in which reinforcing fibers are in contact with a roller to which the sizing agent-containing liquid is attached, and a sizing agent-containing liquid is atomized to form reinforcing fibers. There is a method of spraying. The sizing agent applying means may be either a batch type or a continuous type, but a continuous type which is good in productivity and can reduce variation is preferably used. At this time, it is preferable to control the concentration and temperature of the sizing agent-containing liquid and the yarn tension of the reinforcing fiber so that the amount of the sizing agent active component attached to the reinforcing fiber is uniform within an appropriate range. Moreover, it is also a preferable aspect that the reinforcing fiber is vibrated with ultrasonic waves when the sizing agent is applied.

  The adhesion amount of the sizing agent is preferably in the range of 0.1 to 10 parts by mass, more preferably in the range of 0.2 to 3 parts by mass with respect to 100 parts by mass of the sizing agent-coated reinforcing fiber. When the adhesion amount of the sizing agent is 0.1 parts by mass or more, when prepreg and weaving the sizing agent-coated reinforcing fiber, it can withstand friction caused by a metal guide that passes therethrough, and generation of fluff is suppressed. The quality of the prepreg using the reinforcing fiber is excellent. On the other hand, when the adhesion amount of the sizing agent is 10 parts by mass or less, the matrix resin is impregnated inside the reinforcing fiber bundle without being inhibited by the sizing agent film around the reinforcing fiber bundle, and void formation is suppressed in the obtained composite material. Therefore, the quality and mechanical properties of the composite material are excellent.

  The thickness of the sizing agent layer applied to the reinforcing fibers after drying is preferably in the range of 2.0 to 20 nm, and the maximum value of the thickness does not exceed twice the minimum value. By such a uniform sizing agent layer, a large effect of improving adhesiveness can be obtained stably, and furthermore, excellent high-order workability can be obtained.

  Reinforcing fibers are produced by applying a sizing agent-containing liquid, then heat-treating, removing the solvent contained in the sizing agent-containing liquid and drying. The heat treatment is considered to have an effect of promoting the formation of a covalent bond between the sizing agent component and the functional group on the surface of the reinforcing fiber and enhancing the adhesion between the reinforcing fiber and the matrix resin. The heat treatment condition is preferably a temperature range of 130 ° C. to 260 ° C., more preferably a temperature range of 160 to 260 ° C., and preferably 30 to 600 seconds. When the temperature is 130 ° C. or higher and 30 seconds or longer, water and organic solvent in which the sizing agent component is dissolved or dispersed can be sufficiently removed. When it is 260 ° C. or lower and 600 seconds or shorter, the operation cost and safety are particularly excellent.

  The heat treatment can also be performed by microwave irradiation and / or infrared irradiation. When the reinforcing fiber is heat-treated by microwave irradiation and / or infrared irradiation, the reinforcing fiber that is the object to be heated can be heated to a desired temperature in a short time. In addition, since the inside of the reinforcing fiber can be quickly heated by microwave irradiation and / or infrared irradiation, the temperature difference between the inside and outside of the reinforcing fiber bundle can be reduced, and the adhesion unevenness of the sizing agent can be reduced. It becomes possible to do.

  Further, when the reinforcing fiber is carbon fiber, as another application means, a method of adding a sizing agent component in the electrolytic solution and applying it to the carbon fiber surface simultaneously with the liquid phase electrolytic oxidation treatment, liquid phase electrolytic oxidation treatment The sizing agent component can be applied to the carbon fiber surface simultaneously with water washing in a later washing step. In these cases, the amount of the sizing agent component attached can be controlled by controlling the concentration and temperature of the electrolytic solution and the yarn tension of the carbon fiber.

  The sizing-coated reinforcing fiber of the present invention is used in the form of, for example, tow, woven fabric, knitted fabric, braid, web, mat, chopped fiber and the like. In particular, for applications that require high specific strength and specific elastic modulus, tows in which carbon fibers are aligned in one direction are most suitable. Further, a prepreg obtained by impregnating a sizing coated reinforcing fiber with a matrix resin is preferably used.

  Next, the prepreg and fiber-reinforced composite material of the present invention will be described. The sizing coated reinforcing fiber in the present invention can be used as a prepreg and a fiber reinforced composite material in combination with a matrix resin.

  As the matrix resin for the prepreg and the fiber reinforced composite material, both a thermosetting resin and a thermoplastic resin can be used. A thermosetting resin is more preferable. Examples of the thermosetting resins include unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins, melamine resins, urea resins, thermosetting polyimide resins, cyanate ester resins, and bismaleimide resins, and their modifications. Body, and a resin obtained by blending two or more of these. Among these, an epoxy resin is preferable because it has an advantage of excellent balance of mechanical properties and small curing shrinkage.

  As an epoxy resin, the epoxy resin composition containing an epoxy compound and a hardening | curing agent is preferable. The epoxy compound is not particularly limited, and is not limited to bisphenol type epoxy compound, amine type epoxy compound, phenol novolac type epoxy compound, cresol novolac type epoxy compound, resorcinol type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy. One or more compounds can be selected and used from among compounds, dicyclopentadiene type epoxy compounds, epoxy compounds having a biphenyl skeleton, isocyanate-modified epoxy compounds, tetraphenylethane type epoxy compounds, triphenylmethane type epoxy compounds, and the like.

  The curing agent is not particularly limited, and examples thereof include an aromatic amine curing agent, dicyanamide or a derivative thereof. In addition, amines such as alicyclic amines, phenol compounds, acid anhydrides, polyamide aminos, organic acid hydrazides, isocyanates, and the like can be used in combination with aromatic amine curing agents.

  Among these, it is preferable to use an epoxy resin composition containing a polyfunctional glycidylamine type epoxy compound and an aromatic diamine curing agent. In general, a matrix resin containing a polyfunctional glycidylamine type epoxy compound and an aromatic diamine curing agent has a high crosslinking density, and can improve the heat resistance and compressive strength of the resulting fiber-reinforced composite material.

  As the polyfunctional glycidylamine type epoxy compound, for example, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol and the like can be preferably used. The polyfunctional glycidylamine type epoxy compound has an effect of improving heat resistance, and the proportion thereof is preferably 30 to 100% by mass in 100% by mass of all epoxy compounds. When the ratio of the glycidylamine type epoxy compound is 30% by mass or more, the compressive strength of the fiber reinforced composite material is improved and the heat resistance is excellent.

  Specific examples of tetraglycidyldiaminodiphenylmethane include, for example, “Sumiepoxy (registered trademark)” ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Tohto Kasei Co., Ltd.), “Araldite (registered trademark)” MY720 (Huntsman). Advanced Materials Co., Ltd.), “jER (registered trademark)” 604 (Japan Epoxy Resin Co., Ltd.) and the like can be used. Specific examples of triglycidylaminophenol or triglycidylaminocresol include, for example, “Sumiepoxy (registered trademark)” ELM100 (manufactured by Sumitomo Chemical Co., Ltd.), “Araldite (registered trademark)” MY0510, and “Araldite (registered trademark)”. “MY0600 (manufactured by Huntsman Advanced Materials Co., Ltd.)”, “jER (registered trademark)” 630 (manufactured by Japan Epoxy Resin Co., Ltd.) and the like can be used.

  The aromatic diamine curing agent is not particularly limited as long as it is an aromatic amine used as a curing agent for an epoxy resin composition. Specifically, 3,3′-diaminodiphenyl sulfone (3,3) is used. 3′-DDS), 4,4′-diaminodiphenyl sulfone (4,4′-DDS), diaminodiphenylmethane (DDM), diaminodiphenyl ether (DADPE), bisaniline, benzyldimethylaniline, 2- (dimethylaminomethyl) phenol ( DMP-10), 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30), tri-2-ethylhexylate of DMP-30, etc., and isomers or derivatives thereof are preferably used. it can. These may be used alone or in combination of two or more.

  Commercially available aromatic amine curing agents include Seika Cure S (manufactured by Wakayama Seika Kogyo Co., Ltd.), MDA-220 (manufactured by Mitsui Chemicals), “jER Cure (registered trademark)” W (Japan Epoxy Resin ( ), And 3,3′-DAS (Mitsui Chemicals), “Lonacure (registered trademark)” M-DEA (Lonza), “Lonzacure (registered trademark)” M-DIPA ( Lonza Co., Ltd.), "Lonzacure (registered trademark)" M-MIPA (Lonza Co., Ltd.) and "Lonzacure (registered trademark)" DETDA 80 (Lonza Co., Ltd.).

  The aromatic diamine curing agent is preferably contained in a stoichiometric amount of 50 to 120% by mass, more preferably 60 to 120% by mass, and even more preferably, with respect to the total epoxy compound contained in the epoxy resin composition. It is 70-90 mass%. When the aromatic amine curing agent is 50% by mass or more of the stoichiometric amount with respect to the total epoxy compound, the heat resistance of the obtained resin cured product is improved. Moreover, when an aromatic amine hardening | curing agent is 120 mass% or less, the toughness of the resin cured material obtained improves.

  Moreover, an effect promoter can also be mix | blended for the purpose of accelerating hardening of an epoxy resin composition. Examples of the curing accelerator include urea compounds, tertiary amines and salts thereof, imidazoles and salts thereof, triphenylphosphine or derivatives thereof, carboxylic acid metal salts and Lewis acids, Bronsted acids and salts thereof, and the like.

  A thermoplastic resin can be blended with the matrix resin of the fiber reinforced composite material in order to improve physical properties such as toughness of the obtained cured resin. Examples of such thermoplastic resins include carbon-carbon bonds, amide bonds, imide bonds (polyetherimide, etc.), ester bonds, ether bonds, siloxane bonds, carbonate bonds, urethane bonds, urea bonds, thioether bonds, A thermoplastic resin having a bond selected from the group consisting of a sulfone bond, an imidazole bond, and a carbonyl bond can be used. For example, those having both heat resistance and toughness such as polysulfone, polyethersulfone, polyetherimide, polyimide, polyamide, polyamideimide, polyphenylene ether, phenoxy resin, and vinyl polymer can be preferably used.

  In particular, polyethersulfone and polyetherimide are preferable because these effects can be exhibited without substantially impairing heat resistance. Polyether sulfones include “Sumika Excel (registered trademark)” 3600P, “Sumika Excel (registered trademark)” 5003P, “Sumika Excel (registered trademark)” 5200P, “Sumika Excel (registered trademark)” 7200P (above, Sumitomo Chemical) Kogyo Co., Ltd.) and polyetherimide include "Ultem (registered trademark)" 1000, "Ultem (registered trademark)" 1010, "Ultem (registered trademark)" 1040 (above, manufactured by Nippon GE Plastics Co., Ltd.) ) Etc. can be used.

  The amount of the thermoplastic resin is preferably 1 to 40 parts by weight, more preferably 1 to 25 parts by weight with respect to 100 parts by weight of the epoxy compound when dissolved in the epoxy resin composition. . On the other hand, when used by dispersing, the amount is preferably 10 to 40 parts by mass, more preferably 15 to 30 parts by mass with respect to 100 parts by mass of the epoxy compound. When the blending amount of the thermoplastic resin is within such a range, the effect of improving toughness is further improved. Moreover, when a thermoplastic resin does not exceed the said range, impregnation property, a tack, drape, and heat resistance become favorable.

  The above thermoplastic resin is preferably uniformly dissolved in the epoxy resin composition or finely dispersed in the form of particles so as not to interfere with the prepreg production process, particularly in terms of impregnation. .

  Furthermore, in order to modify the matrix resin, a thermosetting resin other than the thermosetting resin used as the matrix resin, elastomer, filler, rubber particles, thermoplastic resin particles, inorganic particles and other additives are blended. You can also.

  As said thermoplastic resin particle, the thing similar to the various thermoplastic resins illustrated previously can be used. Of these, polyamide particles and polyimide particles are preferably used. Among polyamides, a semi-IPN (polymer interpenetrating network structure) is formed with nylon 12, nylon 6, nylon 11, nylon 6/12 copolymer or an epoxy compound described in Example 1 of JP-A-01-104624. Nylon (semi-IPN nylon) can give particularly good adhesive strength with thermosetting resin, so the delamination strength of the fiber-reinforced composite material at the time of falling weight impact is high, and the impact resistance is improved. It is preferable because it is high.

  The shape of the thermoplastic resin particles may be spherical particles, non-spherical particles, or porous particles, but since the spherical particles do not deteriorate the flow characteristics of the resin, they are excellent in viscoelasticity and have no origin of stress concentration. This is preferable in terms of giving high impact resistance.

  As the rubber particles, cross-linked rubber particles, and core-shell rubber particles obtained by graft polymerization of a different polymer on the surface of the cross-linked rubber particles are preferably used from the viewpoint of handleability and the like.

  In addition, inorganic particles such as silica, alumina, smectite, and synthetic mica can be added to the matrix resin in order to adjust fluidity such as thickening of the matrix resin within the range that does not impair the effects of the present invention.

  Prepreg is a wet method in which the above matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to lower the viscosity and impregnated into the reinforcing fiber, or a hot melt method in which the viscosity is lowered by heating and impregnated into the reinforcing fiber (dry method). Or the like.

  The wet method is a method in which a reinforcing fiber is immersed in a matrix resin solution, then pulled up, and the solvent is evaporated using an oven or the like. The hot melt method is a method in which a reinforcing resin is impregnated directly with a matrix resin whose viscosity is reduced by heating, or a film in which a matrix resin is coated on a release paper or the like is once prepared, and then the film is applied from both sides or one side of the reinforcing fiber. And reinforcing the fiber by impregnating the matrix resin with heat and pressure. The hot melt method is a preferable method because there is substantially no solvent remaining in the prepreg.

  After laminating the obtained prepreg, a fiber-reinforced composite material can be produced by a method of heating and curing the matrix resin while applying pressure to the laminate. As a method for applying heat and pressure, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, a vacuum pressure molding method, and the like are employed. The fiber reinforced composite material does not go through a prepreg, and includes, for example, a filament winding method, a hand layup method, a resin injection molding method, “SCRIMP (registered trademark)”, a resin film infusion method, and a resin transfer method. It can also be produced by a molding method such as a molding method.

  The fiber reinforced composite material of the present invention is, for example, a personal computer, a display, an OA device, a mobile phone, a portable information terminal, a facsimile, a compact disc, a portable MD, a portable radio cassette, a PDA (a portable information terminal such as an electronic notebook), a video. Cameras, digital still cameras, optical equipment, audio equipment, air conditioners, lighting equipment, recreational goods, toy goods, and other electrical and electronic equipment casings and internal parts such as trays and chassis and their cases; mechanical parts, panels, etc. Applications of building materials: Motor parts, alternator terminals, alternator connectors, IC regulators, light meter potentiometer bases, suspension parts, exhaust gas valves and other valves, fuel-related, exhaust and intake system pipes, air intake nozzles -Kel, intake manifold, various arms, various frames, various hinges, various bearings, fuel pump, gasoline tank, CNG tank, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, Brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, thermostat base for air conditioner, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, wiper motor Related parts, distributor, starter switch, starter relay, transmission wire harness , Window washer nozzle, air conditioner panel switch board, coil for fuel related electromagnetic valve, connector for fuse, battery tray, AT bracket, headlamp support, pedal housing, handle, door beam, protector, chassis, frame, armrest, horn terminal, Step motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, noise shield, radiator support, spare tire cover, seat shell, solenoid bobbin, engine oil filter, ignition device case, under cover, scuff plate, pillar trim, propeller shaft, Wheel, fender, fascia, bumper, bumper beam, bonnet, aero parts, platform Automobiles and motorcycle-related parts such as motorcycles, cowl louvers, roofs, instrument panels, spoilers and various modules; parts and skins, landing gear pods, winglets, spoilers, edges, ladders, elevators, fairings, ribs and other aircraft And related parts or members; and skins, windmill blades, and the like. In particular, it is preferably used for aircraft members, windmill blades, automobile outer plates, casings of electronic devices, trays, chassis, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not restrict | limited by these Examples.

  The materials and components used as sizing agent components in each Example and each Comparative Example are as follows.

Polyrotaxane (A): (A-1 to A-3)
(A-1) "Celum (registered trademark)" superpolymer SH2400P (manufactured by Advanced Soft Materials Co., Ltd .: cyclic molecule is α-cyclodextrin; linear molecule is polyethylene glycol having a weight average molecular weight of 20,000; blocking group Is an adamantane group; the cyclic molecule is modified by a graft chain made of poly (ε-caprolactone)
(A-2) “Celum (registered trademark)” superpolymer SH1310P (manufactured by Advanced Soft Materials Co., Ltd.): cyclic molecule is α-cyclodextrin; linear molecule is polyethylene glycol having a weight average molecular weight of 11,000; blocking group Is an adamantane group; the cyclic molecule is modified by a graft chain made of poly (ε-caprolactone)
(A-3) "Celum (registered trademark)" superpolymer SH3400P (manufactured by Advanced Soft Materials Co., Ltd .: cyclic molecule is α-cyclodextrin; linear molecule is polyethylene glycol having a weight average molecular weight of 35,000; blocking group Is an adamantane group; the cyclic molecule is modified by a graft chain made of poly (ε-caprolactone).

Surfactant (B): (B-1 to B-4)
(B-1) “Neopelex” G-25 (manufactured by Kao Corporation: anionic surfactant; sodium dodecylbenzenesulfonate)
(B-2) “Leodol” SP-S10V (manufactured by Kao Corporation: nonionic surfactant; sorbitan monostearate; HLB value 4.7)
(B-3) “Emulgen” 102KG (manufactured by Kao Corporation: nonionic surfactant; polyoxyethylene lauryl ether; HLB value 6.3)
(B-4) “Leodol” TW-L120 (manufactured by Kao Corporation: nonionic surfactant; polyoxyethylene sorbitan monolaurate; HLB value 16.7)
Compound having an epoxy group: (C-1 to C-3)
(C-1) “Denacol (registered trademark)” EX-521 (manufactured by Nagase ChemteX Corporation: polyglycerin polyglycidyl ether)
(C-2) “Denacol (registered trademark)” EX-411 (manufactured by Nagase ChemteX Corporation: pentaerythritol polyglycidyl ether)
(C-3) “Denacol (registered trademark)” EX-611 (manufactured by Nagase ChemteX Corporation: sorbitol polyglycidyl ether).

Example 1
First, an aqueous emulsion containing at least a polyrotaxane (A) and a surfactant (B) was prepared, and the dispersibility of the aqueous emulsion was evaluated.

<Dispersibility evaluation of (A) (B) component containing aqueous solution>
30 parts by mass of (A-1) as the polyrotaxane (A) and 30 parts by mass of (B-1) as the surfactant (B) were weighed and mixed while heating at 80 ° C. Next, while adding water heated to 80 ° C. little by little, stirring was performed until the solution concentration became 1% by mass to obtain an aqueous emulsion. After naturally cooling to 20 ° C. with stirring, stirring was stopped and the mixture was allowed to stand at 20 ° C. for 1 hour, and then the supernatant was removed to obtain a precipitate. The precipitate was vacuum-dried at 80 ° C. for 1 hour, and the weight of the precipitate with respect to the total amount of the component (A) and the component (B) was measured. It was confirmed that the precipitate weight relative to the initial amount was less than 20% by mass, and the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 1.

  A sufficiently dispersed aqueous emulsion can be used as an aqueous sizing agent solution that can be applied to reinforcing fibers. A with an initial sediment weight of less than 20% by mass, A with 20% by mass to less than 30% by mass, B with 30% by mass to less than 50% by mass, and D with 50% by mass or more. did.

Thereafter, in the evaluation of the dispersibility of the aqueous solution containing the components (A) and (B), the contribution of the sizing component to the mode I interlaminar fracture toughness (G _Ic ) and 0 ° tensile strength of the reinforcing fiber composite material In order to grasp, a mechanical test was conducted. This step consists of the following step I, step II and step III.

Step I: Step of producing carbon fiber A copolymer composed of 99 mol% of acrylonitrile and 1 mol% of itaconic acid was spun and fired, and the total number of filaments was 12,000, specific gravity 1.8, strand tensile strength 700 kgf / mm ^2, to obtain a carbon fiber strand tensile modulus 33,000kgf / mm ^2. Next, the carbon fiber was subjected to liquid phase electrolytic oxidation treatment using an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / liter as an electrolytic solution. The carbon fiber subjected to the liquid phase electrolytic oxidation treatment was subsequently washed with water and dried in heated air at a temperature of 150 ° C. to obtain a carbon fiber subjected to surface oxidation treatment.

Step II: Step for producing sizing coated carbon fiber and evaluation 30 parts by mass of (A-1) as polyrotaxane (A), 30 parts by mass of (B-1) as surfactant (B), epoxy compound ( As C), 70 parts by mass of (C-1) was dissolved in dimethylformamide as a solvent to prepare a sizing agent-containing liquid. The sizing agent-containing liquid was applied to the surface-oxidized carbon fiber obtained as described above using a dipping method, and then heat treated at a temperature of 210 ° C. for 180 seconds to obtain a sizing agent-coated carbon fiber bundle. . The adhesion amount of the sizing agent was measured by the method described below and adjusted so that the adhesion amount of the sizing agent was 0.5 parts by mass with respect to 100 parts by mass of the sizing agent-coated carbon fibers.

<Measurement of sizing agent adhesion>
About 2 g of a sizing agent-coated carbon fiber bundle was weighed (W1) (reading to the fourth decimal place), then placed in an electric furnace (capacity 120 cm ³ ) set at a temperature of 450 ° C. in a nitrogen stream of 50 ml / min. The sizing agent was completely pyrolyzed for a minute. Then, the carbon fiber bundle was transferred to a container in a dry nitrogen stream at 20 liters / minute and cooled for 15 minutes, and the carbon fiber bundle was weighed (W2) (read to the fourth decimal place). The sizing agent adhesion amount with respect to 100 parts by mass of the sizing agent-coated carbon fiber bundle was determined from the following formula.
Sizing agent adhesion amount (parts by mass) = [W1 (g) −W2 (g)] / [W1 (g)] × 100
In this example, the measurement was performed twice, and the average value was defined as the sizing agent adhesion amount.

Step III: Preparation of prepreg, molding and evaluation of carbon fiber reinforced composite laminate <Preparation of prepreg>
First, bisphenol A type epoxy resin, “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation) 60 parts by mass, tetraglycidyldiaminodiphenylmethane, ELM434 (manufactured by Sumitomo Chemical Co., Ltd.) 40 parts by mass, 4, 4 ′ -40 parts by mass of diaminodiphenylsulfone, “Seika Cure (registered trademark)” S (manufactured by Wakayama Seika Co., Ltd.) and 10 parts by mass of polyethersulfone “Sumika Excel (registered trademark)” PES5003P (manufactured by Sumitomo Chemical Co., Ltd.) A kneaded epoxy resin composition was prepared, and this was coated on a release paper with a resin basis weight of 30 g / m ² using a knife coater to produce a primary resin film. This primary resin film is superimposed on both sides of a sizing agent-coated carbon fiber (weight per unit area 190 g / m ² ) aligned in one direction, and the epoxy resin composition is applied to the sizing agent-coated carbon fiber while heating and pressing using a heat roll. A primary prepreg was produced by impregnation. Next, a resin composition was prepared by further kneading 80 parts by mass of the above-mentioned epoxy resin composition with “Trepearl (registered trademark)” TN (manufactured by Toray Industries, Inc., average particle size: 13.0 μm). A secondary resin film was prepared by coating the release paper with a resin basis weight of 20 g / m ² using a coater. This secondary resin film was overlapped on both sides of the primary prepreg, and the primary prepreg was impregnated with the resin composition to produce a target prepreg.

<Formation of Carbon Fiber Reinforced Composite Material and Measurement of Mode I Interlaminar Fracture Toughness (G _Ic )>
The prepreg produced as described above was cut and unidirectionally laminated, and then heat-cured using an autoclave to produce a unidirectional reinforcing material (carbon fiber reinforced composite material). When the mode I interlaminar fracture toughness (G _Ic ) at the initial stage of crack growth was determined according to the double-holding test described in JIS K7086 (1993), it showed a sufficiently high value. The results are shown in Table 1.

High mode I interlaminar fracture toughness (G _Ic ) means that the adhesion between the carbon fiber and the matrix resin is good, and the toughness of the fiber-reinforced composite material is high. In the present invention, the mode I interlaminar fracture toughness (G _Ic ) is preferably in the range of 700 J / m ² or more. In Table 1, the value of the mode I interlaminar fracture toughness _{(G Ic)} are marked 950J / ^{m 2} or more of A, less than 700 J / ^{m 2} or more 950J / ^{m 2} B, less than 700 J / ^{m 2} at C ing.

<Formation of carbon fiber reinforced composite material and 0 ° tensile strength measurement>
As described in JIS K7017 (1999), the fiber direction of the unidirectional fiber reinforced composite material was defined as the axial direction, the axial direction was defined as the 0 ° axis, and the axis orthogonal direction was defined as 90 °.

A unidirectional prepreg within 24 hours after production is cut into a predetermined size, and after stacking six pieces in one direction, a vacuum bag is formed and a temperature of 180 ° C., a pressure of 6 kg / cm ² , 2 is applied using an autoclave. It was cured with time to obtain a unidirectional reinforcing material (carbon fiber reinforced composite material). The unidirectional reinforcing material was cut into a width of 12.7 mm and a length of 230 mm, and a glass fiber reinforced plastic tab having a length of 1.2 mm and a length of 50 mm was bonded to both ends to obtain a test piece. The test piece thus obtained was subjected to a 0 ° tensile test at a crosshead speed of 1.27 mm / min using a universal testing machine manufactured by Instron. It was found that the 0 ° tensile strength was high and the carbon fiber strength could be fully utilized. The results are shown in Table 1.

A high 0 ° tensile strength means that the adhesion between the carbon fiber and the matrix resin is good, and stress is efficiently transmitted between the resin and the fiber. In the present invention, the 0 ° tensile strength is preferably 3000 MPa or more. In Table 1, the value of mode I interlaminar fracture toughness (G _Ic ) is 3500 MPa or more as A, 3250 MPa or more and less than 3500 MPa as B, 3000 MPa or more and less than 3250 MPa as C, and less than 3000 MPa as D.

(Examples 2 to 10)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was confirmed that the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 1.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 1 was performed.

Step II: Step for producing sizing coated carbon fiber and evaluation Sizing agent coated carbon fiber was obtained in the same manner as in Example 1 except that the ratio of each component was as shown in Table 1. .

Step III: Preparation of prepreg, molding of carbon fiber reinforced composite material laminate and evaluation In the same manner as in Example 1, a unidirectional reinforcing material (carbon fiber reinforced composite material) was prepared and evaluated for mechanical properties. The I interlaminar fracture toughness (G _Ic ) and 0 ° tensile strength showed sufficiently high values. The results are shown in Table 1.

(Examples 11 to 17)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was confirmed that the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 2.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 1 was performed.

Step II: Step of producing sizing-coated carbon fiber and evaluation A sizing-coated carbon fiber was obtained in the same manner as in Example 1, except that the ratio of each component was as shown in Table 2. .

Step III: Preparation of prepreg, molding of carbon fiber reinforced composite material laminate and evaluation In the same manner as in Example 1, a unidirectional reinforcing material (carbon fiber reinforced composite material) was prepared and evaluated for mechanical properties. The I interlaminar fracture toughness (G _Ic ) and 0 ° tensile strength showed sufficiently high values. The results are shown in Table 2.

(Example 18)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was confirmed that the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 2.

Step I: Step of producing carbon fiber as raw material The same procedure as in Example 1 was performed.

Step II: Step of producing sizing coated carbon fiber and evaluation 30 parts by mass of (A-1) as polyrotaxane (A), 21 parts by mass of (B-1) as surfactant (B), (B- 4) weighed 9 parts by mass and mixed while heating at 80 ° C. Subsequently, stirring was performed while adding water heated to 80 ° C. little by little until the solution concentration became 1% by mass, and then natural cooling was performed to 20 ° C. with stirring to obtain an aqueous emulsion. 70 parts by mass of (C-1) as an epoxy compound (C) was added to the obtained aqueous emulsion to prepare an aqueous sizing agent solution. This sizing agent aqueous solution was applied to the surface-oxidized carbon fiber obtained as described above using an immersion method, and then heat treated at a temperature of 210 ° C. for 180 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was measured by the method described below and adjusted so that the adhesion amount of the sizing agent was 0.5 parts by mass with respect to 100 parts by mass of the sizing agent-coated carbon fibers.

Step III: Preparation of prepreg, molding of carbon fiber reinforced composite material laminate and evaluation In the same manner as in Example 1, a unidirectional reinforcing material (carbon fiber reinforced composite material) was prepared and evaluated for mechanical properties. The I interlaminar fracture toughness (G _Ic ) and 0 ° tensile strength showed sufficiently high values. The results are shown in Table 2.

(Comparative Example 1)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was found that the aqueous emulsion was not dispersed and could not be used as a sizing agent for reinforcing fibers. The results are shown in Table 3.

(Comparative Example 2)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was confirmed that the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 3.

Step I: Step of producing carbon fiber The same procedure as in Example 1 was performed.

Step II: Step for producing sizing-coated carbon fiber and evaluation Sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except that the sizing agent-containing liquid was prepared using only the component (B-2). .

Step III: Preparation of prepreg, molding of carbon fiber reinforced composite material laminate and evaluation In the same manner as in Example 1, a unidirectional reinforcing material (carbon fiber reinforced composite material) was prepared and evaluated for mechanical properties. The I interlaminar fracture toughness (G _Ic ) and 0 ° tensile strength were low. The results are shown in Table 3.

(Comparative Example 3)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was found that the aqueous emulsion was not dispersed and could not be used as a sizing agent for reinforcing fibers. The results are shown in Table 3.

(Comparative Example 4)
<Dispersibility evaluation of (A) (B) component containing aqueous solution>
Same as Example 1. It was confirmed that the aqueous emulsion was sufficiently dispersed and could be used as a sizing agent for reinforcing fibers. The results are shown in Table 3.

Step I: Step of producing carbon fiber The same procedure as in Example 1 was performed.

Step II: Step for producing sizing-coated carbon fiber and evaluation Sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except that the sizing agent-containing liquid was adjusted with the components shown in Table 3.

Step III: Preparation of prepreg, molding of carbon fiber reinforced composite material laminate and evaluation In the same manner as in Example 1, a unidirectional reinforcing material (carbon fiber reinforced composite material) was prepared and evaluated for mechanical properties. The I interlaminar fracture toughness (G _Ic ) showed a high value, but the 0 ° tensile strength showed a low value. The results are shown in Table 3.

Claims (19)

A sizing agent containing at least a polyrotaxane (A) and a surfactant (B) and having a mass ratio (B) / (A) of (A) to (B) of 0.1 to 1.5 is applied to the reinforcing fibers. Sizing agent coated reinforcing fiber. The sizing agent-coated reinforcing fiber according to claim 1, wherein the surfactant (B) contains at least a nonionic active agent. The sizing agent-coated reinforcing fiber according to claim 2, wherein the surfactant (B) includes a nonionic surfactant having an HLB value of less than 10. The sizing agent-coated reinforcing fiber according to claim 3, wherein the surfactant (B) contains at least a nonionic surfactant having an HLB value of less than 10 and a nonionic surfactant having an HLB value of 10 or more. The sizing agent-coated reinforcing fiber according to any one of claims 1 to 4, wherein the sizing agent further comprises a compound having an epoxy group. The sizing agent according to claim 5, wherein the compound having an epoxy group is a compound having two or more epoxy groups in a molecule and selected from a polyether type polyepoxy compound and a polyol type polyepoxy compound. Application reinforcing fiber. The glycidyl ether obtained by the reaction of at least one compound selected from glycerin, diglycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol, and arabitol with epichlorohydrin, the compound having an epoxy group. The sizing agent-coated reinforcing fiber according to claim 5, which is a type epoxy compound. The sizing agent-coated reinforcing fiber according to any one of claims 1 to 7, wherein the sizing agent contains 5 to 50% by mass of polyrotaxane (A) based on the total amount of the sizing agent. The sizing agent-coated reinforcing fiber according to any one of claims 1 to 8, wherein the linear molecule that is a constituent component of the polyrotaxane (A) has a weight average molecular weight of 15,000 or more and 30,000 or less. The sizing agent-coated reinforcing fiber according to any one of claims 1 to 9, wherein the polyrotaxane (A) comprises cyclodextrin and polyethylene glycol as constituent components. The cyclodextrin is modified with a polymer chain, and the polymer chain includes a bond selected from an —O— bond and an —NH— bond, and a group selected from an alkylene group and an alkenylene group. The sizing agent-coated reinforcing fiber according to claim 10. The sizing agent-coated reinforcing fiber according to any one of claims 1 to 11, wherein the reinforcing fiber is a carbon fiber. A sizing agent-containing liquid containing at least a polyrotaxane (A) and a surfactant (B) and having a mass ratio (B) / (A) of (A) and (B) of 0.1 to 1.5 is used as a reinforcing fiber. A method for producing a sizing agent-coated reinforcing fiber to be applied. The method for producing sizing agent-coated reinforcing fibers according to claim 13, wherein the sizing agent-containing liquid is an aqueous sizing agent solution comprising an aqueous emulsion. The manufacturing method of the sizing agent application | coating reinforcement fiber of Claim 14 which apply | coats the sizing agent aqueous solution which further contains the compound which has an epoxy group to the said aqueous emulsion to a reinforcement fiber. A method of producing a sizing agent-coated reinforcing fiber by applying a sizing agent containing polyrotaxane (A) and a surfactant (B) to a reinforcing fiber and then heat-treating the sizing agent in the step of applying the sizing agent. The adhering amount of the agent is 0.1 to 10 parts by mass with respect to 100 parts by mass of the sizing agent-coated reinforcing fiber, and the conditions for the heat treatment are within a temperature range of 160 to 260 ° C. for 30 to 600 seconds. The method for producing a sizing agent-coated reinforcing fiber according to claim 13 or 14. A prepreg comprising the sizing agent-coated reinforcing fiber according to claim 1 and a thermosetting resin. The prepreg according to claim 17, wherein the thermosetting resin is an epoxy resin. A fiber-reinforced composite material obtained by curing the prepreg according to claim 17 or 18.