JP2013104145A - Sizing agent-coated carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber having superior adhesiveness between the carbon fiber and a matrix resin, and high-order processability.SOLUTION: The carbon fiber has a sizing agent deposited thereon, which comprises: 100 pts. mass of (A1) an epoxy compound having two or more epoxy groups and/or (A2) an epoxy compound having one or more epoxy groups and at least one or more functional groups selected from an unsaturated group, a hydroxyl group, an amido group, an imido group, an urethane group, an urea group, a sulfonyl group and sulfo group, as a (A) component; and 0.1-25 pts. mass of a hindered amine compound having the following general formula (I), as a (B) component.

Description

  The present invention relates to a method for producing sizing agent-coated carbon fibers that are suitably used for aircraft members, spacecraft members, automobile members, ship members, and the like. More specifically, the present invention relates to a sizing agent-coated carbon fiber that is excellent in adhesiveness with a matrix resin and excellent in high-order processability.

  Since carbon fiber is lightweight and has excellent strength and elastic modulus, many composite materials combined with various matrix resins are used for aircraft members, spacecraft members, automobile members, ship members, civil engineering and building materials, and sporting goods. Used in the field. In a composite material using carbon fibers, in order to make use of the excellent characteristics of carbon fibers, it is important that the adhesion between the carbon fibers and the matrix resin is excellent.

  In order to improve the adhesion between the carbon fiber and the matrix resin, a method of introducing an oxygen-containing functional group on the surface of the carbon fiber is usually performed by subjecting the carbon fiber to oxidation treatment such as gas phase oxidation or liquid phase oxidation. . For example, a method has been proposed in which the interlaminar shear strength, which is an index of adhesion, is improved by subjecting carbon fibers to electrolytic treatment (see Patent Document 1). However, in recent years, as the level of required properties for composite materials has improved, the adhesion that can be achieved by such oxidation treatment alone is becoming insufficient.

  On the other hand, since carbon fiber is brittle and has poor convergence and friction resistance, fluff and yarn breakage are likely to occur in the high-order processing step. For this reason, the method of apply | coating a sizing agent to carbon fiber is performed normally.

  For example, a method of applying diglycidyl ether of bisphenol A as a sizing agent to carbon fibers has been proposed (see Patent Documents 2 and 3). In addition, a method of applying a polyalkylene oxide adduct of bisphenol A as a sizing agent to carbon fibers has been proposed (see Patent Documents 4 and 5). Moreover, the method of apply | coating what added the epoxy group to the polyalkylene oxide addition product of bisphenol A as a sizing agent to carbon fiber is proposed (refer patent document 6 and 7). Furthermore, a method of applying an epoxy adduct of polyalkylene glycol as a sizing agent to carbon fibers has been proposed (see Patent Documents 8, 9 and 10).

  According to these methods, it is known that the converging property and friction resistance of the carbon fiber are improved. However, these conventional proposals do not have a technical idea of positively improving the adhesion between the carbon fiber and the matrix resin by using a sizing agent, and actually greatly improve the adhesion between the carbon fiber and the matrix resin. I couldn't.

  As described above, the sizing agent is conventionally used as a so-called paste agent for the purpose of improving the high-order workability, and the sizing agent has hardly been studied to improve the adhesion between the carbon fiber and the matrix resin. . Moreover, even in the studied examples, the effect of improving the adhesiveness is insufficient, or the effect is limited only in combination with a special carbon fiber.

  For example, a method of applying N, N, N ′, N′-tetraglycidylmetaxylylenediamine as a sizing agent to carbon fibers has been proposed (see Patent Document 11). However, this proposed method shows that the interlaminar shear strength, which is an index of adhesion, is improved as compared with the case where glycidyl ether of bisphenol A is used, but the effect of improving adhesion is still insufficient. Met. In addition, N, N, N ′, N′-tetraglycidylmetaxylylenediamine used in this proposal contains an aliphatic tertiary amine in the skeleton and has nucleophilicity. In particular, there is a problem that the carbon fiber bundle becomes hard and the high-order workability is lowered.

  Further, a method of applying a mixture of a vinyl compound monomer having a glycidyl group and an amine curing agent for epoxy resin as a sizing agent to carbon fibers has been proposed (see Patent Document 12). However, although this proposed method has been shown to improve the interlaminar shear strength, which is an index of adhesion, compared with the case where no amine curing agent is used, the effect of improving adhesion is still insufficient. It was. In addition, the glycidyl group and amine curing agent react with each other in the drying process of the sizing agent to increase the molecular weight. As a result, the carbon fiber bundle becomes hard and the high-order workability decreases, and the gaps between the carbon fibers become narrower and the resin. There was a problem that the impregnation property of the resin deteriorated. Other methods using a sizing agent in which an epoxy compound and an amine curing agent are used in combination have been proposed (see Patent Document 13). However, according to this proposal, the handling property and impregnation property of the fiber bundle are improved, but the adhesion between the carbon fiber and the epoxy matrix resin is inhibited by the film formation of the high molecular weight sizing agent on the carbon fiber surface. There was a case.

  Furthermore, a method of applying an amine compound to carbon fibers has been proposed (see Patent Document 14). However, although the proposed method shows that the interlaminar shear strength, which is an index of adhesion, is improved as compared with the case where nothing is applied, the effect of improving adhesion is still insufficient. In this proposal, there is no detailed description of the adhesion improvement mechanism, but it is presumed that it is roughly the following mechanism. That is, in this proposal, diethylenetriamine containing a primary amino group, xylenediamine, piperidine containing a secondary amino group, and imidazole are used as amine compounds. It is considered that the active hydrogen acts on the epoxy matrix resin and accelerates the curing reaction. For example, the hydroxyl group formed by the reaction of the epoxy matrix and the amine compound, the carboxyl group on the carbon fiber surface, the hydroxyl group, etc. It is considered that the action is formed and the adhesion is improved. However, as described above, the result of improvement in adhesion is still insufficient with this proposal, and it cannot be said that the demands for composite materials in recent years are satisfied.

  Furthermore, as another example using an amine compound as a sizing agent, a method using a thermosetting resin and a cured product of an amine compound has been proposed (see Patent Document 15). In this proposal, m-xylenediamine containing a primary amino group and piperazine containing a secondary amino group are used as an amine compound. The purpose of this proposal is to improve the convergence and handling of the carbon fiber bundle by actively reacting the active hydrogen contained in the amine compound with a thermosetting resin represented by an epoxy resin to produce a cured product. Met. This carbon fiber bundle was limited to chopped applications, and the mechanical properties related to the adhesiveness of the molded product after melt-kneading with a thermoplastic resin were still insufficient.

  Further, carbon fibers having surface oxygen concentration O / C, surface hydroxyl group concentration and carboxyl group concentration within specific ranges are used, and an aliphatic compound having a plurality of epoxy groups is applied to the carbon fiber as a sizing agent. A method has been proposed (see Patent Document 16). However, this proposed method has been shown to improve EDS, which is an index of adhesion, but the effect of improving the adhesion between the carbon fiber and the matrix resin is still insufficient, and adhesion The improvement effect was limited to be manifested only when combined with special carbon fibers.

Japanese Patent Laid-Open No. 04-361619 Japanese Patent Laid-Open No. 50-059589 JP-A-57-171767 JP 07-009444 A JP 2000-336577 A JP 61-028074 A Japanese Patent Laid-Open No. 01-272867 JP-A-57-128266 JP 59-009273 A JP 62-033872 A JP 52-059794 A JP-A-52-045673 JP 2005-146429 A JP-A-52-045672 JP 09-217281 A Japanese Patent Laid-Open No. 07-279040

  Accordingly, in view of the above-mentioned problems in the prior art, an object of the present invention is to provide a sizing agent-coated carbon fiber that is excellent in adhesion between the carbon fiber and the matrix resin and that is excellent in high-order processability.

  The present inventors have found that when a sizing agent containing a specific ratio of a specific epoxy compound and a specific hindered amine compound is attached to the carbon fiber, the adhesion between the carbon fiber and the matrix resin can be improved. I thought.

  That is, the present invention provides (A) as component (A1) an epoxy compound having two or more epoxy groups in the molecule, and / or (A2) one or more epoxy groups in the molecule, and an unsaturated group. , 100 parts by mass of an epoxy compound having at least one functional group selected from hydroxyl group, amide group, imide group, urethane group, urea group, sulfonyl group, and sulfo group, Is a sizing agent-coated carbon fiber to which a sizing agent comprising 0.1 to 25 parts by mass of a hindered amine compound having a

(Wherein R ₁ represents a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, the hydrocarbon group may have a hydroxyl group, and the CH ₂ group in the hydrocarbon group is —O— , —O—CO— or —CO—O— may be substituted, and R ₂ represents hydrogen, a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, and the hydrocarbon group has a hydroxyl group. And the CH ₂ group in the hydrocarbon group may be substituted by —O—, —O—CO— or —CO—O—.)
According to a preferred embodiment of the sizing agent-coated carbon fiber of the present invention, the epoxy equivalent of the (A) epoxy compound is less than 360 g / mol.
According to a preferred embodiment of the sizing agent-coated carbon fiber of the present invention, the (A) epoxy compound contains an aromatic ring in the molecule.
According to a preferred embodiment of the sizing agent-coated carbon fiber of the present invention, (A) the epoxy compound is either a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, or tetraglycidyl diaminodiphenylmethane.
According to a preferred embodiment of the sizing agent-coated carbon fiber of the present invention, the surface oxygen concentration O / C measured by X-ray photoelectron spectroscopy of the carbon fiber is 0.05 to 0.5.

According to the present invention, when (A) a sizing agent containing a specific epoxy compound as a main component is blended with a specific amount of (B) a specific hindered amine compound, the epoxy compound and the carbon fiber surface are originally included. Formation of a covalent bond is promoted between an oxygen-containing functional group or an oxygen-containing functional group such as a carboxyl group and a hydroxyl group introduced by an oxidation treatment, and a carbon fiber having significantly excellent adhesion to a matrix resin can be obtained. it can.

  Hereinafter, in more detail, the form for implementing the sizing agent application | coating carbon fiber of this invention is demonstrated.

  In the present invention, as the component (A), (A1) an epoxy compound having two or more epoxy groups in the molecule, and / or (A2) one or more epoxy groups in the molecule, an unsaturated group, a hydroxyl group , An amide group, an imide group, a urethane group, a urea group, a sulfonyl group, and a sulfo group, 100 parts by mass of an epoxy compound having at least one functional group, as the component (B), the above general formula (I) A sizing agent-coated carbon fiber to which a sizing agent comprising 0.1 to 25 parts by mass of a hindered amine compound having a slag is attached.

  The mechanism by which the adhesiveness is improved by applying a sizing agent containing a specific amount of component (A) and component (B) to carbon fiber and heat-treating under specific conditions is not certain. The tertiary amine contained in the hindered amine compound is anionized by extracting the hydrogen ion of the oxygen-containing functional group such as a carboxyl group and a hydroxyl group of the carbon fiber used in the present invention, and (A) It is considered that the epoxy group contained in the component undergoes a nucleophilic reaction. Thereby, the strong bond of the carbon fiber used by this invention and the epoxy in a sizing agent is formed. On the other hand, in relation to the matrix resin, each of (A1) and (A2) will be described as follows.

  In the case of (A1), it is considered that the remaining epoxy groups not participating in the covalent bond with the carbon fiber used in the present invention react with the matrix resin-containing functional group to form a covalent bond, or form a hydrogen bond. It is done. In particular, when the matrix resin is an epoxy resin, it is considered that a strong interface can be formed by the reaction between the epoxy group of (A1) and the epoxy group of the matrix resin, or the reaction via the amine curing agent contained in the epoxy resin. . In the case of (A2), the epoxy group of (A2) forms a covalent bond with an oxygen-containing functional group such as a carboxyl group and a hydroxyl group of the carbon fiber used in the present invention, but the remaining unsaturated group, hydroxyl group, amide group, The imide group, urethane group, urea group, sulfonyl group, or sulfo group is considered to form an interaction such as a covalent bond or a hydrogen bond depending on the matrix resin. If the matrix resin is a resin having an unsaturated group such as vinyl ester or unsaturated polyester, the unsaturated group of (A2) and the unsaturated group of the matrix resin can be radically reacted to form a strong interface. is there. If the matrix resin is an epoxy resin, the hydroxyl group, amide group, imide group, urethane group, urea group, sulfonyl group, or sulfo group of (A2) and the epoxy group of the matrix resin or amine curing agent and epoxy group It is considered that a strong interface can be formed by the interaction with the hydroxyl group formed by the reaction. Further, if the matrix resin is a thermoplastic resin typified by polyamide, polyester and acid-modified polyolefin, (A2) hydroxyl group, amide group, imide group, urethane group, urea group, sulfonyl group, or sulfo group It is considered that a strong interface can be formed by the interaction with amide groups, ester groups, acid anhydride groups, carboxyl groups such as terminals, hydroxyl groups, and amino groups contained in these matrix resins.

  That is, in the case of (A1), the remaining epoxy groups not involved in the covalent bond with the carbon fiber are unsaturated groups, hydroxyl groups, amide groups, imide groups, urethane groups, urea groups, sulfonyl groups in the case of (A2). It is considered to have a function corresponding to a group or a sulfo group.

  In the present invention, the epoxy compound of component (A) is preferably an epoxy resin having 3 or more epoxy groups, and more preferably an epoxy resin having 4 or more epoxy groups. When the epoxy compound of component (A) is an epoxy resin having 3 or more epoxy groups in the molecule, even if one epoxy group forms a covalent bond with an oxygen-containing functional group on the surface of the carbon fiber, the remaining These two or more epoxy groups can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion is further improved. There is no particular upper limit on the number of epoxy groups, but if it is 10 or more, the adhesiveness may be saturated.

  In this invention, it is preferable that the epoxy equivalent of the epoxy compound of (A) component is less than 360 g / mol, More preferably, it is less than 270 g / mol, More preferably, it is less than 180 g / mol. When the epoxy equivalent is less than 360 g / mol, covalent bonds are formed at a high density, and the adhesion between the carbon fiber and the matrix resin is further improved. There is no particular lower limit of the epoxy equivalent, but the adhesiveness may be saturated at less than 90 g / mol.

  In the present invention, the (A) epoxy compound is preferably an epoxy resin having 3 or more types of two or more functional groups, and more preferably an epoxy resin having 4 or more types of 2 or more functional groups. The functional group possessed by the epoxy compound is preferably selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, or a sulfo group in addition to the epoxy group. (A) When the epoxy compound is an epoxy resin having three or more epoxy groups or other functional groups in the molecule, one epoxy group forms a covalent bond with an oxygen-containing functional group on the carbon fiber surface However, the remaining two or more epoxy groups or other functional groups can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion is further improved. There is no particular upper limit on the number of epoxy groups, but if it is 10 or more, the adhesiveness may be saturated.

  In the present invention, the epoxy compound as component (A) preferably has at least one aromatic ring in the molecule, and more preferably has at least two aromatic rings. In a fiber-reinforced composite material composed of carbon fibers and a matrix resin, a so-called interface layer in the vicinity of the carbon fibers may be affected by the carbon fibers or the sizing agent and have different characteristics from the matrix resin. (A) When the epoxy compound has one or more aromatic rings, a rigid interface layer is formed, the stress transmission ability between the carbon fiber and the matrix resin is improved, and the fiber reinforced composite material has a 0 ° tensile strength, etc. Mechanical properties are improved. There is no particular upper limit on the number of aromatic rings, but if it is 10 or more, the mechanical properties may be saturated.

  In the present invention, the (A1) epoxy compound is preferably a phenol novolac epoxy resin, a cresol novolac epoxy resin, or tetraglycidyldiaminodiphenylmethane. These epoxy resins have a large number of epoxy groups, a small epoxy equivalent, and have two or more aromatic rings. In addition to improving the adhesion between carbon fiber and matrix resin, fiber reinforced composite materials Improve mechanical properties such as 0 ° tensile strength. The bifunctional or higher functional epoxy resin is more preferably a phenol novolac type epoxy resin and a cresol novolac type epoxy resin.

  In the present invention, (A1) specific examples of the epoxy compound having two or more epoxy groups include, for example, a glycidyl ether type epoxy resin derived from a polyol, and a glycidyl amine type epoxy derived from an amine having a plurality of active hydrogens. Examples thereof include a resin, a glycidyl ester type epoxy resin derived from polycarboxylic acid, and an epoxy resin obtained by oxidizing a compound having a plurality of double bonds in the molecule.

  Examples of the glycidyl ether type epoxy resin 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 The glycidyl ether type epoxy resin obtained by reaction with phosphorus is mentioned. Further, as glycidyl ether type epoxy resins, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, trimethylene glycol, 1, 2 -Butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4 -Cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, glycerol, diglycerol, polyglycerol, trimethylolpropane, penta Risuritoru, sorbitol, and arabitol and a glycidyl ether type epoxy resin obtained by reaction of epichlorohydrin are also exemplified. Examples of the glycidyl ether type epoxy resin include a glycidyl ether type epoxy resin having a dicyclopentadiene skeleton and a glycidyl ether type epoxy resin having a biphenyl aralkyl skeleton.

  Examples of the glycidylamine type epoxy resin include N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, 1,3-bis (aminomethyl) cyclohexane, m-xylylenediamine, m-phenylenediamine, Examples include 4,4′-diaminodiphenylmethane and 9,9-bis (4-aminophenyl) fluorene.

  Furthermore, for example, as a glycidylamine type epoxy resin, both the hydroxyl group and amino group of aminophenols of m-aminophenol, p-aminophenol, and 4-amino-3-methylphenol are reacted with epichlorohydrin. And epoxy resin obtained.

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

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

  In addition to these epoxy resins, (A1) epoxy compounds used in the present invention include epoxy resins such as triglycidyl isocyanurate. Furthermore, the epoxy resin synthesize | combined from the epoxy resin mentioned above as a raw material, for example, the epoxy resin synthesize | combined by the oxazolidone ring formation reaction from bisphenol A diglycidyl ether and tolylene diisocyanate is mentioned.

  In the present invention, (A2) one or more epoxy groups and at least one or more functional groups selected from unsaturated groups, hydroxyl groups, amide groups, imide groups, urethane groups, urea groups, sulfonyl groups, and sulfo groups. Specific examples of the epoxy compound having, for example, a compound having an epoxy group and an unsaturated group, a compound having an epoxy group and a hydroxyl group, a compound having an epoxy group and an amide group, a compound having an epoxy group and an imide group, and an epoxy group Examples thereof include compounds having a urethane group, compounds having an epoxy group and a urea group, compounds having an epoxy group and a sulfonyl group, and compounds having an epoxy group and a sulfo group.

  Examples of the compound having an epoxy group and an unsaturated group include epoxy synthesized by addition reaction of 1,2-epoxy-7-octene, 1,2-epoxy-9-decane and bisphenol A diglycidyl ether with vinyl acetate. Examples thereof include resins.

  Examples of the compound having an epoxy group and a hydroxyl group include sorbitol-type polyglycidyl ether and glycerol-type polyglycidyl ether. Specifically, Denacol (registered trademark) EX-611, EX-612, EX-614, EX -614B, EX-622, EX-512, EX-521, EX-421, EX-313, EX-314 and EX-321 (manufactured by Nagase ChemteX Corporation).

  Examples of the compound having an epoxy group and an amide group include glycidyl benzamide and amide-modified epoxy resin. The amide-modified epoxy can be obtained by reacting an epoxy group of an epoxy resin 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. Specifically, “Denacol (registered trademark)” EX-731 (manufactured by Nagase ChemteX Corporation) and the like can be mentioned.

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

  Examples of the compound having an epoxy group and a urea group include a urea-modified epoxy resin. The urea-modified epoxy can be obtained by reacting the epoxy group of an epoxy resin 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 bisphenol S-type epoxy.

  Examples of the compound having an epoxy group and a sulfo group include glycidyl p-toluenesulfonate and glycidyl 3-nitrobenzenesulfonate.

  (B) used in the present invention is required to be a tertiary amine compound and / or a tertiary amine salt having a molecular weight of 100 g / mol or more.

Since the hindered amine compound having the general formula (I) of (B) used in the present invention has a tertiary amine in the molecule, the tertiary amine is an oxygen-containing functional group such as a carboxyl group and a hydroxyl group of carbon fiber. It is considered that the anionized functional group and the epoxy group contained in (A) undergo a nucleophilic reaction to form a strong interface after pulling out the hydrogen ions. In addition, the methyl group bonded to the carbon atom adjacent to the tertiary amine has a moderately small steric hindrance in the molecular structure, so that the reaction promoting effect is enhanced and the adhesiveness is improved.
The hindered amine compound having the general formula (I) (B) used in the present invention may be a salt neutralized with a proton donor. Here, the proton donor means a compound having active hydrogen that can be donated as a proton to a compound having a tertiary amino group. The active hydrogen refers to a hydrogen atom that is donated as a proton to a basic compound.

  Examples of proton donors include inorganic acids, carboxylic acids, organic acids such as sulfonic acids and phenols, alcohols, mercaptans, and 1,3-dicarbonyl compounds.

  Specific examples of inorganic acids include sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, and amidosulfuric acid. Is mentioned. Of these, sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid are preferably used.

  The carboxylic acids are classified into aliphatic polycarboxylic acids, aromatic polycarboxylic acids, S-containing polycarboxylic acids, aliphatic hydroxycarboxylic acids, aromatic hydroxycarboxylic acids, aliphatic monocarboxylic acids, and aromatic monocarboxylic acids, The following compounds are mentioned.

  Specific examples of the aliphatic polycarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, peric acid, azelaic acid, sebacic acid, undencanic acid, dodecanedioic acid, tridecanedioic acid, Tetradecanedioic acid, pentadecanedioic acid, methylmalonic acid, ethylmalonic acid, propylmalonic acid, butylmalonic acid, pentylmalonic acid, hexylmalonic acid, dimethylmalonic acid, diethylmalonic acid, methylpropylmalonic acid, methylbutylmalonic acid, Ethylpropylmalonic acid, dipropylmalonic acid, methylsuccinic acid, ethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methyl-3- Ethyl glutaric acid, 3,3-diethyl glutaric acid, 3,3-dimethyl glutar Examples include acid, 3-methyladipic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid.

  Specific examples of the aromatic polycarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid.

  Specific examples of the S-containing polycarboxylic acid include thiodipropionic acid.

  Specific examples of the aliphatic hydroxycarboxylic acid include glycolic acid, lactic acid, tartaric acid and castor oil fatty acid.

  Specific examples of the aromatic hydroxycarboxylic acid include salicylic acid, mandelic acid, 4-hydroxybenzoic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid and 6-hydroxy-2-naphthoic acid. Can be mentioned.

  Specific examples of the aliphatic monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, octylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, Examples include behenic acid, undecanoic acid, acrylic acid, methacrylic acid, crotonic acid, and oleic acid.

  Specific examples of the aromatic monocarboxylic acid include benzoic acid, cinnamic acid, naphthoic acid, toluic acid, ethyl benzoic acid, propyl benzoic acid, isopropyl benzoic acid, butyl benzoic acid, isobutyl benzoic acid, sec-butyl benzoic acid, Tertiary butyl benzoic acid, methoxy benzoic acid, ethoxy benzoic acid, propoxy benzoic acid, isopropoxy benzoic acid, butoxy benzoic acid, isobutoxy benzoic acid, second butoxy benzoic acid, tertiary butoxy benzoic acid, amino benzoic acid, N-methyl Aminobenzoic acid, N-ethylaminobenzoic acid, N-propylaminobenzoic acid, N-isopropylaminobenzoic acid, N-butylaminobenzoic acid, N-isobutylaminobenzoic acid, N-secondary butylaminobenzoic acid, N- Tertiary butylaminobenzoic acid, N, N-dimethylaminobenzoic acid, N, N-die Arylamino benzoic acid, and nitrobenzoic acid and fluorosilicone benzoate.

  Of the above carboxylic acids, aromatic polycarboxylic acids, aliphatic monocarboxylic acids, and aromatic carboxylic acids are preferably used. Specifically, phthalic acid, formic acid, and octylic acid are preferably used.

  The sulfonic acid can be classified into aliphatic sulfonic acid and aromatic sulfonic acid, and examples thereof include the following compounds.

  Among the aliphatic sulfonic acids, specific examples of monovalent saturated aliphatic sulfonic acids include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, isopropylsulfonic acid, butanesulfonic acid, isobutylsulfonic acid, t-butylsulfonic acid. , Pentanesulfonic acid, isopentylsulfonic acid, hexanesulfonic acid, nonanesulfonic acid, decanesulfonic acid, undecanesulfonic acid, dodecanesulfonic acid, tridecanesulfonic acid, tetradecanesulfonic acid, n-octylsulfonic acid, dodecylsulfonic acid and cetyl A sulfonic acid etc. are mentioned.

  The aliphatic sulfonic acid may be an unsaturated aliphatic sulfonic acid, and specific examples of the unsaturated aliphatic sulfonic acid include ethylene sulfonic acid and 1-propene-1-sulfonic acid.

  Among aliphatic sulfonic acids, specific examples of divalent or higher aliphatic sulfonic acids include methionic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,1-propanedisulfonic acid, 1, Examples thereof include 3-propanedisulfonic acid and polyvinyl sulfonic acid.

  The aliphatic sulfonic acid may be an oxyaliphatic sulfonic acid having a hydroxyl group, and specific examples of the oxyaliphatic sulfonic acid include isethionic acid and 3-oxy-propanesulfonic acid.

  The aliphatic sulfonic acid may be a sulfo crude carboxylic acid ester, and specific examples of the sulfoaliphatic carboxylic acid include sulfoacetic acid and sulfosuccinic acid.

  Among the aliphatic sulfonic acids, specific examples of the sulfoaliphatic carboxylic acid ester include di (2-ethylhexyl) sulfosuccinic acid.

  The aliphatic sulfonic acid may be fluorosulfonic acid, and specific examples of the fluorosulfonic acid include trifluoromethanesulfonic acid, perfluoroethanesulfonic acid, perfluoropropanesulfonic acid, perfluoroisopropylsulfonic acid, perfluorobutanesulfonic acid. Acid, perfluoroisobutylsulfonic acid, perfluorot-butylsulfonic acid, perfluoropentanesulfonic acid, perfluoroisopentylsulfonic acid, perfluorohexanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, perfluoroundecane Sulfonic acid, perfluorododecanesulfonic acid, perfluorotridecanesulfonic acid, perfluorotetradecanesulfonic acid, perfluoron-octylsulfonic acid, perfluorododecyl Sulfonic acids and perfluoro cetyl acid and the like.

  Among aromatic sulfonic acids, specific examples of monovalent aromatic sulfonic acids include benzenesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, o-xylene-4-sulfonic acid. M-xylene-4-sulfonic acid, 4-ethylbenzenesulfonic acid, 4-propylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-dodecylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 2-methyl-5- Examples include isopropylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, t-butylnaphthalenesulfonic acid, 2,4,5-trichlorobenzenesulfonic acid, benzylsulfonic acid, and phenylethanesulfonic acid.

  Among aromatic sulfonic acids, specific examples of di- or higher valent aromatic sulfonic acids include m-benzenedisulfonic acid, 1,4-naphthalenedisulfonic acid, 1,5-naphthalenedisulfonic acid, 1,6-naphthalenedisulfonic acid. 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 1,3,6-naphthalenetrisulfonic acid, sulfonated polystyrene, and the like.

  The aromatic sulfonic acid may be an oxyaromatic sulfonic acid. Specific examples of the oxyaromatic sulfonic acid include phenol-2-sulfonic acid, phenol-3-sulfonic acid, phenol-4-sulfonic acid, anisole- o-sulfonic acid, anisole-m-sulfonic acid, phenetol-o-sulfonic acid, phenetol-m-sulfonic acid, phenol-2,4-disulfonic acid, phenol-2,4,6-trisulfonic acid, anisole-2 , 4-disulfonic acid, phenetole-2,5-disulfonic acid, 2-oxytoluene-4-sulfonic acid, pyrocatechin-4-sulfonic acid, veratrol-4-sulfonic acid, resorcin-4-sulfonic acid, 2-oxy -1-methoxybenzene-4-sulfonic acid, 1,2-dioxybenzene-3,5-disulfonic acid, reso Shin-4,6-disulfonic acid, hydroquinone sulfonic acid, hydroquinone-2,5-disulfonic acid and 1,2,3-oxybenzene-4-sulfonic acid and the like.

  The aromatic sulfonic acid may be a sulfoaromatic carboxylic acid. Specific examples of the sulfoaromatic carboxylic acid include o-sulfobenzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, and 2,4-disulfo. Benzoic acid, 3-sulfophthalic acid, 3,5-disulfophthalic acid, 4-sulfoisophthalic acid, 2-sulfoterephthalic acid, 2-methyl-4-sulfobenzoic acid, 2-methyl-3,5-disulfobenzoic acid, 4 -Propyl-3-sulfobenzoic acid, 2,4,6-trimethyl-3-sulfobenzoic acid, 2-methyl-5-sulfoterephthalic acid, 5-sulfosalicylic acid and 3-oxy-4-sulfobenzoic acid It is done.

  The aromatic sulfonic acid may be a thioaromatic sulfonic acid. Specific examples of the thioaromatic sulfonic acid include thiophenol sulfonic acid, thioanisole-4-sulfonic acid, and thiophenetol-4-sulfonic acid. Can be mentioned.

  Among the aromatic sulfonic acids, specific examples having other functional groups include benzaldehyde-o-sulfonic acid, benzaldehyde-2,4-disulfonic acid, acetophenone-o-sulfonic acid, acetophenone-2,4-disulfonic acid, benzophenone. -O-sulfonic acid, benzophenone-3,3'-disulfonic acid, 4-aminophenol-3-sulfonic acid, anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid, anthraquinone-1,5-disulfonic acid, anthraquinone Examples include -1,8-disulfonic acid, anthraquinone-2,6-disulfonic acid, and 2-methylanthraquinone-1-sulfonic acid.

  Among the above sulfonic acids, monovalent aromatic sulfonic acid is preferably used, and specifically, benzenesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid and m-toluenesulfonic acid are preferably used.

Specific examples of phenols containing one active hydrogen per molecule include phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, and tert-butylphenol. Cyclohexylphenol, dimethylphenol, methyl-tert-butylphenol, di-tert-butylphenol, chlorophenol, bromophenol, nitrophenol, methoxyphenol, and methyl salicylate.
Specific examples of phenols containing two active hydrogens in one molecule include hydroquinone, resorcinol, catechol, methylhydroquinone, tert-butylhydroquinone, benzylhydroquinone, phenylhydroquinone, dimethylhydroquinone, methyl-tert-butylhydroquinone, di- -Tert-butylhydroquinone, trimethylhydroquinone, methoxyhydroquinone, methylresorcinol, tert-butylresorcinol, benzylresorcinol, phenylresorcinol, dimethylresorcinol, methyl-tert-butylresorcinol, di-tert-butylresorcinol, trimethylresorcinol, methoxyresorcinol, methyl Catechol, tert-butylcatechol, benzylcatechol, phenylcatechol , Dimethylcatechol, methyl-tert-butylcatechol, di-tert-butylcatechol, trimethylcatechol, methoxycatechol, biphenol, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl, 4 Biphenols such as 4,4′-dihydroxy-3,3 ′, 5,5′-tetra-tert-butylbiphenyl, bisphenol A, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbisphenol A, 4,4′-dihydroxy-3,3 ′, 5,5′-tetra-tert-butylbisphenol A, bisphenol F, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbisphenol F, 4,4′-dihydroxy-3,3 ′, 5,5′-tetra-tert-butylbisphenol F, bisphenol A 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbisphenol AD, 4,4′-dihydroxy-3,3 ′, 5,5′-tetra-tert-butylbisphenol AD. .
Furthermore, as phenols containing two active hydrogens in one molecule, bisphenols represented by the following structural formulas (II) to (VIII), terpene phenols, structural formulas (IX), and (X) Compounds and the like.
Furthermore, specific examples of phenols containing three active hydrogens in one molecule include trihydroxybenzene and tris (p-hydroxyphenyl) methane. Specific examples of those containing 4 active hydrogens in one molecule include tetrakis (p-hydroxyphenyl) ethane. Other specific examples include novolaks of phenols such as phenol, alkylphenol and halogenated phenol.

  Of the above phenols, phenol and phenol novolac are preferably used.

  Examples of alcohols include those containing two hydroxyl groups in one molecule, such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butane. Diol, 1,4-butanediol, 1,5-pentanediol, 1,1-dimethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4- Pentanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dodecahydrobisphenol A, ethylene oxide adduct of bisphenol A represented by structural formula (XI), structural formula (XII The propylene oxide adduct of bisphenol A represented by the structural formula (XIII) Ethylene oxide adducts of dodeca hydro bisphenol A, propylene oxide adduct of dodeca hydro bisphenol A represented by the structural formula (XIV), glycerol, trimethylol ethane and trimethylol propane. In addition, specific examples of alcohols containing four hydroxyl groups in one molecule include pentaerythritol.

Examples of mercaptans include mercaptans containing one active hydrogen in one molecule. For example, methanethiol, ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 2-methyl -1-propanethiol, 2-butanethiol, 2-methyl-2-propanethiol, 1-pentanethiol, 1-hexanethiol, 1-heptanethiol, 1-octanethiol, cyclopentanethiol, cyclohexanethiol, benzyl mercaptan, Examples include benzene thiol, toluene thiol, chlorobenzene thiol, bromobenzene thiol, nitrobenzene thiol and methoxybenzene thiol.
Specific examples of mercaptans containing two active hydrogens in one molecule include 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 2,2 '-Oxydiethanethiol, 1,6-hexanedithiol, 1,2-cyclohexanedithiol, 1,3-cyclohexanedithiol, 1,4-cyclohexanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol and 1 , 4-benzenethiol and the like.

  Examples of 1,3-dicarbonyl compounds include 2,4-pentanedione, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 3,5-heptanedione, 4 , 6-nonanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1-phenyl-1,3-butanedione, 1,3- Diphenyl-1,3-propanedione, 1,3-cyclopentanedione, 2-methyl-1,3-cyclopentanedione, 2-ethyl-1,3-cyclopentanedione, 1,3-cyclohexanedione, 2- Examples include methyl-1,3-cyclohexanedione, 2-ethyl-cyclohexanedione, 1,3-indandione, ethyl acetoacetate and diethyl malonate.

R _{1 in the} general formula (I) of the present invention represents a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, and the hydrocarbon group may have a hydroxyl group, and CH ₂ in the hydrocarbon group. The group may be substituted by -O-, -O-CO- or -CO-O-. By setting the number of carbon atoms to be between 1 and 22, the steric hindrance of the molecular structure is moderately small, the reaction promoting effect is increased, and the adhesion is improved. More preferably, it exists in the range of 1-14, More preferably, it exists in the range of 1-8. On the other hand, when the number of carbon atoms exceeds 22, the steric hindrance of the molecular structure may be somewhat large and the reaction promoting effect may be reduced.

R _{2 in the} general formula (I) of the present invention represents hydrogen, a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, and the hydrocarbon group may have a hydroxyl group, The CH ₂ group may be substituted by —O—, —O—CO— or —CO—O—.

  Here, a C1-C22 hydrocarbon group is a group which consists only of a carbon atom and a hydrogen atom, and any of a saturated hydrocarbon group and an unsaturated hydrocarbon group may be included, even if it contains a ring structure. Also good. As the hydrocarbon group, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclohexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, oleyl group, A docosyl group, a benzyl group, a phenyl group, etc. are mentioned.

Further, the hydrocarbon group having 1 to 22 carbon atoms may be one in which a CH ₂ group in the hydrocarbon group is substituted with —O—. Examples of the case where the CH ₂ group in the hydrocarbon group having 1 to 22 carbon atoms is substituted by —O— include, for example, a straight chain, such as a methoxymethyl group, an ethoxymethyl group, a propoxymethyl group, butoxy Polyether groups such as methyl group, phenoxymethyl group, methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, phenoxyethyl group, methoxyethoxymethyl group, methoxyethoxyethyl group, polyethylene glycol group and polypropylene glycol group Can be mentioned. Examples of cyclic compounds include ethylene oxide, tetrahydrofuran, oxepane, and 1,3-dioxolane.

Further, the hydrocarbon group having 1 to 22 carbon atoms may be one in which a CH ₂ group in the hydrocarbon group is substituted by —O—CO— or —CO—O—. Examples of the case where the CH ₂ group in the hydrocarbon group having 1 to 22 carbon atoms is substituted by —O—CO— or —CO—O— include, for example, an acetoxymethyl group, an acetoxyethyl group, an acetoxypropyl group, Examples include an acetoxybutyl group, a methacryloyloxyethyl group, a benzoyloxyethyl group, a methoxycarbonyl group, and an ethoxycarbonyl group.

  The hydrocarbon group having 1 to 22 carbon atoms may have a hydroxyl group, and examples of the case where the hydrocarbon group having 1 to 22 carbon atoms has a hydroxyl group include, for example, a hydroxymethyl group and a hydroxyethyl group. , Hydroxypropyl group, hydroxybutyl group, hydroxypentyl group, hydroxyhexyl group, hydroxycyclohexyl group, hydroxyoctyl group, hydroxydecyl group, hydroxydodecyl group, hydroxytetradecyl group, hydroxyhexadecyl group, hydroxyoctadecyl group, hydroxyoleyl group And a hydroxydocosyl group and the like.

  Specific examples of the hindered amine compound having the general formula (I) as the component (B) used in the present invention include, for example, tetrakis (1,2,2,4-butane-1,2,3,4-tetracarboxylic acid). 6,6-pentamethyl-4-piperidinyl) (for example, LA-52 (manufactured by ADEKA)), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (for example, LA-72 ( ADEKA), TINUVIN765 (BASF))), carbonic acid = bis (2,2,6,6-tetramethyl-1-undecyloxypiperidin-4-yl) (for example, LA-81 (made by ADEKA) )), 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (for example, LA-82 (manufactured by ADEKA)), malonic acid-2-((4-methoxypheny ) Methylene), 1,3-bis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester, Chimassorb 119, 2-dodecyl-N- (1,2,2,6,6-pentamethyl-4) -Piperidinyl) succin-imide, 1,2,3,4-butanetetracarboxylic acid 1-hexadecyl 2,3,4-tris (1,2,2,6,6-pentamethyl-4-piperidinyl), 1,2 , 3,4-Butanetetracarboxylic acid 1,2,3-tris (1,2,2,6,6-pentamethyl-4-piperidinyl) 4-tridecyl, decanedioic acid 1-methyl 10- (1,2, 2,6,6-pentamethyl-4-piperidinyl), 4- (ethenyloxy) -1,2,2,6,6-pentamethylpiperidine, 2-((3,5-bis (1,1-dimethylethyl) -4- Droxyphenyl) methyl) -2-butylpropanedioic acid bis (1,2,2,6,6-pentamethyl-4-piperidinyl), 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-methanol, 2,2,6,6-tetramethyl-4-hydroxypiperidine- 1-ethanol, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-propanol, LA-63P (manufactured by ADEKA), LA-68 (manufactured by ADEKA), TINUVIN622LD (manufactured by BASF), TINUVIN144 (Manufactured by BASF).

  These hindered amine compounds may be used alone or in combination of two or more.

  In the sizing agent used in the present invention, 0.1 to 25 parts by mass of the hindered amine compound having the general formula (I) of the component (B) is blended with 100 parts by mass of the epoxy compound of the component (A). Is required, preferably 0.5 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 2 to 8 parts by mass. When the blending amount is less than 0.1 parts by mass, the covalent bond formation between the epoxy compound of component (A) and the oxygen-containing functional group on the carbon fiber surface is not promoted, and the adhesion between the carbon fiber and the matrix resin Is insufficient. On the other hand, when the blending amount is more than 25 parts by mass, the hindered amine compound having the general formula (I) as the component (B) covers the carbon fiber surface, the formation of the covalent bond is inhibited, and the adhesion between the carbon fiber and the matrix resin. Is insufficient.

  In the present invention, the sizing agent may contain one or more components other than the epoxy compound as the component (A) and the hindered amine compound having the general formula (I) as the component (B). For example, polyalkylene oxides such as polyethylene oxide and polypropylene oxide, compounds obtained by adding polyalkylene oxides such as polyethylene oxide and polypropylene oxide to higher alcohols, polyhydric alcohols, alkylphenols, and styrenated phenols, and ethylene oxide and propylene oxide. Nonionic surfactants such as block copolymers are preferably used. Moreover, you may add a polyester resin, an unsaturated polyester compound, etc. suitably in the range which does not affect the effect of this invention.

  In the present invention, the sizing agent can be diluted with a solvent. Examples of such a solvent include water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Among them, handling is easy and advantageous from the viewpoint of safety. Therefore, water is preferably used.

  In this invention, it is preferable that the adhesion amount of a sizing agent is the range of 0.1-10 mass parts with respect to 100 mass parts of carbon fibers, More preferably, it is the range of 0.2-3 mass parts. When the sizing agent is attached in an amount of 0.1 part by mass or more, when carbon fiber is prepreg and weaved, it can withstand friction caused by a metal guide that passes therethrough, and generation of fluff can be suppressed. Excellent quality such as smoothness. On the other hand, if the amount of sizing agent attached is 10 parts by mass or less, a matrix resin such as an epoxy resin is impregnated inside the carbon fiber bundle without being obstructed by the sizing agent film around the carbon fiber bundle, and in the resulting composite material The generation of voids is suppressed, the quality of the composite material is excellent, and at the same time the mechanical properties are excellent.

  In the present invention, the thickness of the sizing agent layer applied to the carbon fiber and dried is preferably in the range of 2 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 further, high-order processability is stable.

  In the present invention, examples of the carbon fiber to which the sizing agent is applied include polyacrylonitrile (PAN) -based, rayon-based, and pitch-based carbon fibers. Of these, PAN-based carbon fibers having an excellent balance between strength and elastic modulus are preferably used.

  Next, a method for producing a PAN-based carbon fiber will be described.

  As a spinning method for obtaining a carbon fiber precursor fiber, spinning methods such as wet, dry, and dry-wet can be used. Among these, it is preferable to use a wet or dry wet spinning method from the viewpoint that a high-strength carbon fiber is easily obtained. As the spinning dope, a polyacrylonitrile homopolymer or copolymer solution or suspension can be used.

  The spinning solution is spun, coagulated, washed with water, and drawn into a precursor fiber by passing it through a die, and the resulting precursor fiber is subjected to a flameproofing treatment and carbonization treatment. Get fiber. As conditions for carbonization treatment and graphitization treatment, the maximum heat treatment temperature is preferably 1100 ° C. or higher, more preferably 1400 to 3000 ° C.

  In the present invention, carbon fibers having fineness are preferably used from the viewpoint of obtaining carbon fibers having high strength and elastic modulus. 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. There is no particular lower limit for the single fiber diameter, but if it is 4.5 μm or less, single fiber cutting is likely to occur in the process, and the productivity may decrease.

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

  In the present invention, 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.

  In the present invention, (A) from the viewpoint that the covalent bond formation between the epoxy compound and the oxygen-containing functional group on the surface of the carbon fiber is promoted, and the adhesiveness is further improved, after the carbon fiber is electrolytically treated with an alkaline electrolyte, Alternatively, it is preferable to apply a sizing agent after electrolytic treatment in an acidic aqueous solution followed by washing with an alkaline aqueous solution. When electrolytic treatment is performed, the excessively oxidized portion on the carbon fiber surface becomes a fragile layer and exists at the interface, which may be the starting point of destruction when made into a composite material. It is considered that formation of a covalent bond is promoted by dissolution and removal with an aqueous solution. Moreover, when the residue of acidic electrolyte exists in the carbon fiber surface, the proton in a residue is supplemented by the hindered amine type compound which has (B) general formula (I), and is a role which should play originally (B) general formula (I ) May hinder the effect of drawing out hydrogen ions of the oxygen-containing functional group on the surface of the carbon fiber. For this reason, it is preferable to carry out an electrolytic treatment in an acidic aqueous solution and then neutralize and wash the acidic electrolytic solution with an alkaline aqueous solution. For the above reasons, a further improvement in adhesion can be obtained by a combination of carbon fibers subjected to a specific treatment and a sizing agent.

  The concentration of the electrolytic solution used in the present invention is preferably in the range of 0.01 to 5 mol / liter, more preferably in the range of 0.1 to 1 mol / liter. When the concentration of the electrolytic solution is 0.01 mol / liter or more, the electrolytic treatment voltage 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 used in the present invention 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 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.

  In the present invention, the amount of electricity in the liquid phase electrolytic oxidation is preferably optimized in accordance with the carbonization degree of the carbon fiber, and a larger amount of electricity is required when processing the carbon fiber having a high elastic modulus.

In the present invention, the current density in the liquid phase electrolytic oxidation is preferably in the range of 1.5 to 1000 amperes / m ² per 1 m ² of the surface area of the carbon fiber in the electrolytic treatment solution, more preferably 3 to 500 amperes. / M ² . When the current density is 1.5 amperes / m ² or more, the efficiency of the electrolytic 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.

  In the present invention, from the viewpoint that (A) the covalent bond formation between the epoxy compound and the oxygen-containing functional group on the carbon fiber surface is promoted, and the adhesion is further improved, the carbon fiber is made alkaline water-soluble after the oxidation treatment. It is preferable to wash. Among these, it is preferable to perform a liquid phase electrolysis treatment with an acidic electrolyte followed by washing with an alkaline aqueous solution.

  In the present invention, the pH of the alkaline aqueous solution used for washing is preferably in the range of 7 to 14, more preferably in the range of 10 to 14. Specific examples of alkaline aqueous solutions 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.

  In the present invention, as a method for washing carbon fibers with an alkaline aqueous solution, for example, a dipping method and a spray method can be used. Especially, it is preferable to use a dip method from a viewpoint that washing | cleaning is easy, Furthermore, it is a preferable aspect to use a dip method, vibrating a carbon fiber with an ultrasonic wave.

  In the present invention, it is preferable that the carbon fiber is washed with an electrolytic 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. Therefore, it is desirable to dry at the lowest possible temperature. Specifically, the drying temperature is preferably 250 ° C. Hereinafter, drying at 210 ° C. or lower is more preferable.

  Examples of the means for applying (coating) the sizing agent to the carbon fiber include a method of immersing the carbon fiber in a sizing liquid through a roller, a method of contacting the carbon fiber with a roller to which the sizing liquid is attached, and a sizing liquid being atomized. There is a method of spraying on carbon fiber. Further, the sizing agent applying means may be either a batch type or a continuous type, but a continuous type capable of improving productivity and reducing variation is preferably used. At this time, it is preferable to control the sizing solution concentration, temperature, yarn tension, and the like so that the amount of the sizing agent active ingredient attached to the carbon fiber is uniformly attached within an appropriate range. Moreover, it is also a preferable aspect that the carbon fiber is vibrated with ultrasonic waves when the sizing agent is applied.

  In this invention, after apply | coating a sizing agent to carbon fiber, it is preferable to heat-process for 30 to 600 second in the temperature range of 160-260 degreeC. The heat treatment conditions are more preferably in the temperature range of 170 to 250 ° C. for 30 to 500 seconds, and further preferably in the temperature range of 180 to 240 ° C. for 30 to 300 seconds. When the heat treatment condition is less than 160 ° C. and / or less than 30 seconds, formation of a covalent bond between the epoxy resin of the sizing agent and the oxygen-containing functional group on the surface of the carbon fiber is hardly promoted, and the carbon fiber and the matrix resin Adhesiveness may be insufficient. On the other hand, when the heat treatment condition exceeds 260 ° C. and / or exceeds 600 seconds, volatilization of the tertiary amine compound and / or tertiary amine salt occurs, and the covalent bond formation is hardly promoted. In some cases, the adhesion of the resin becomes insufficient.

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

  In the present invention, the strand strength of the obtained carbon fiber bundle 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 the obtained carbon fiber bundle is 220 GPa or more, More preferably, it is 240 GPa or more, More preferably, it is 280 GPa or more.

  In the present invention, the strand tensile strength and elastic modulus of the carbon fiber bundle can be determined according to the following procedure in accordance with the resin impregnated strand test method of JIS-R-7608 (2004). As the resin formulation, “Celoxide (registered trademark)” 2021P (manufactured by Daicel Chemical Industries) / 3 boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / Acetone = 100/3/4 (part by mass) is used. As curing conditions, normal pressure, 130 ° C., and 30 minutes are used. Ten strands of the carbon fiber bundle were measured, and the average value was defined as the strand tensile strength and the strand elastic modulus.

  In the present invention, 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 measured by X-ray photoelectron spectroscopy. The thing within the range of 05-0.50 is preferable, More preferably, it is a thing within the range of 0.06-0.30, More preferably, it is a thing within the range of 0.07-0.20. 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 is determined by X-ray photoelectron spectroscopy according to the following procedure. First, after cutting the carbon fiber from which the sizing agent and the like adhering to the carbon fiber surface with a solvent was cut to 20 mm, and spreading and arranging on a copper sample support base, using AlKα ₁ and ₂ as the X-ray source, The sample chamber is kept at 1 × 10 ⁻⁸ Torr. The kinetic energy value (KE) of the main peak of C _1s is set to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area, _K.P. E. Is obtained by drawing a straight base line in the range of 1191 to 1205 eV. O _1s peak area, E. Is obtained by drawing a straight base line in the range of 947 to 959 eV.

Here, the surface oxygen concentration is 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. As the X-ray photoelectron spectroscopy apparatus, ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. was used, and the sensitivity correction value unique to the apparatus was 2.33.

  Then, the composite material using the sizing agent application | coating carbon fiber of this invention is demonstrated. As the matrix resin, a thermosetting resin and a thermoplastic resin are used.

  Examples of the thermosetting resin include unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins, melamine resins, urea resins, cyanate ester resins, and bismaleimide resins. Among them, it is preferable to use an epoxy resin because it has an advantage of excellent balance of mechanical properties and small curing shrinkage. For the purpose of improving toughness and the like, the thermosetting resin can contain a thermoplastic resin described later or an oligomer thereof.

  Examples of the thermoplastic resin include “polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and liquid crystalline polyester; polyethylene (PE), Polyolefin resins such as polypropylene (PP), polybutylene, acid-modified polyethylene (m-PE), acid-modified polypropylene (m-PP), and acid-modified polybutylene; polyoxymethylene (POM), polyamide (PA), polyphenylene sulfide (PPS) ), Etc .; polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyethernitrile (P) N); fluorinated resin such as polytetrafluoroethylene; crystalline resin such as “liquid crystal polymer (LCP)”, styrene resin such as “polystyrene (PS), acrylonitrile styrene (AS), acrylonitrile butadiene styrene (ABS)”, polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), unmodified or modified polyphenylene ether (PPE), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone ( PSU), polyethersulfone, polyarylate (PAR) "and other amorphous resins; phenolic resins, phenoxy resins, polystyrene elastomers, polyolefin elastomers, polyurethane elastomers, polyesters There are at least one thermoplastic resin selected from a copolymer, a modified body, and the like such as a lastmer, a polyamide-based elastomer, a polybutadiene-based elastomer, a polyisoprene-based elastomer, various thermoplastic elastomers such as a fluorine-based resin and an acrylonitrile-based elastomer. Preferably used. Among these, at least one selected from the group consisting of polyarylene sulfide resins, polyether ether kenton resins, polyphenylene ether resins, polyoxymethylene resins, polyamide resins, polyester resins, polycarbonate resins, styrene resins, and polyolefin resins. A thermoplastic resin is preferable because it has a large interaction with (A1) and / or (A2) and can form a strong interface. In addition, as a thermoplastic resin, the thermoplastic resin composition containing multiple types of these thermoplastic resins may be used in the range which does not impair the objective of this invention.

  Next, the composite material when the matrix resin is a thermosetting resin will be described.

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

  The prepreg can be prepared by a wet method in which a matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to lower the viscosity and impregnated, and a hot melt method (dry method) in which the viscosity is decreased by heating and impregnated. .

  The wet method is a method in which carbon fibers are immersed in a matrix resin solution, and then lifted and the solvent is evaporated using an oven. The hot melt method is a method in which a matrix resin whose viscosity is reduced by heating is directly reinforced fiber. Or a coating film prepared from a matrix resin is once placed on a release paper or the like, and then the carbon fiber is coated with a matrix resin by heating and pressurizing the film from both sides or one side of the carbon fiber. It is a method of impregnating. The hot melt method is a preferable method because substantially no solvent remains in the prepreg.

  After laminating the obtained prepreg, a composite material is 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 packing molding method, a wrapping tape method, an internal pressure molding method, and the like are employed. The composite material is formed by directly impregnating the matrix resin with carbon fiber without using a prepreg, followed by heat curing, for example, a hand lay-up method, a resin injection molding method, a resin transfer molding method, etc. It can also be produced by the method. In these methods, it is preferable to prepare a resin by mixing two liquids of a matrix resin main component and a curing agent immediately before use.

  Next, the composite material when the matrix resin is a thermoplastic resin will be described.

  Composite materials using thermoplastic resin as the matrix resin include, for example, injection molding (injection compression molding, gas assist injection molding, insert molding, etc.), blow molding, rotational molding, extrusion molding, press molding, transfer molding, and filament winding molding. However, injection molding is preferably used from the viewpoint of productivity.

  As the form of the molding material used for such molding, pellets, stampable sheets, prepregs and the like can be used, but the most preferable molding material is a pellet used for injection molding. The pellets generally refer to those obtained by kneading a thermoplastic resin and chopped fibers or continuous fibers in an extruder, and extruding and pelletizing. In the above-mentioned pellet, the fiber length in the pellet is shorter than the length in the pellet longitudinal direction, and the pellet includes a long fiber pellet. The long fiber pellets, as described in Japanese Examined Patent Publication No. 63-37694, have fibers arranged substantially parallel to the longitudinal direction of the pellet, and the fiber length in the pellet is equal to or longer than the pellet length. It points to what is. In this case, the thermoplastic resin may be impregnated or coated in the fiber bundle. In particular, in the case of a long fiber pellet coated with a thermoplastic resin, the fiber bundle may be pre-impregnated with a resin having the same viscosity as the coated fiber or a resin having a lower viscosity (or lower molecular weight) than the coated resin. Good.

  In order for the composite material to have excellent electrical conductivity and mechanical properties (particularly strength and impact resistance), it is effective to increase the fiber length in the molded product. Among the pellets, it is preferable to use long fiber pellets.

  Examples of the use of the composite material comprising the sizing agent-coated carbon fiber and the thermosetting resin and / or the thermoplastic resin of the present invention include, for example, a personal computer, a display, an OA device, a mobile phone, a portable information terminal, a facsimile, a compact disc, and a portable. Electric and electronic equipment such as MD, portable radio cassette, PDA (personal information terminal such as electronic notebook), video camera, digital still camera, optical equipment, audio, air conditioner, lighting equipment, entertainment equipment, toy goods, and other home appliances Housings and internal parts such as trays and chassis, and building materials such as cases, mechanism parts, panels, motor parts, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light days, suspension parts, exhaust gas valves, etc. Various valves, fuel related, exhaust or intake system pipes, air intake nozzle snorkel, intake manifold, various arms, various frames, various hinges, various bearings, fuel pump, gasoline tank, CNG tank, engine cooling water joint, carburetor main Body, carburetor spacer, exhaust gas sensor, cooling water 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 Valves, brush holders for radiator motors, water pump impellers, turbine vanes, wiper motor related parts, distributors 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, flange Automobiles, motorcycle-related parts, parts and skins, landing gear pods, winglets, spoilers, edges, such as Aisher, bumper, bumper beam, bonnet, aero parts, platform, cowl louver, roof, instrument panel, spoiler and various modules Aircraft-related parts such as ladders, elevators, failings, and ribs, members and outer plates, 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 Next, although an Example demonstrates this invention concretely, this invention is not restrict | limited by these Examples.

<Strand tensile strength and elastic modulus of carbon fiber bundle>
The strand tensile strength and strand elastic modulus of the carbon fiber bundle were determined according to the following procedure in accordance with the resin impregnated strand test method of JIS-R-7608 (2004). As the resin formulation, “Celoxide” (registered trademark) 2021P (manufactured by Daicel Chemical Industries) / 3 boron fluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / Acetone = 100/3/4 (parts by mass) is used. As curing conditions, normal pressure, temperature of 125 ° C., and time of 30 minutes were used. Ten strands of the carbon fiber bundle were measured, and the average value was defined as the strand tensile strength and the strand elastic modulus.

<Surface oxygen concentration of carbon fiber (O / C)>
The surface oxygen concentration (O / C) of the carbon fiber was determined by X-ray photoelectron spectroscopy according to the following procedure. First, the carbon fiber from which the dirt adhering to the surface with a solvent is removed is cut to about 20 mm and spread on a copper sample support. Next, the sample support is set in the sample chamber, and the inside of the sample chamber is kept at 1 × 10 ⁻⁸ Torr. Subsequently, AlKα ₁ and ₂ were used as an X-ray source, and measurement was performed with a photoelectron escape angle of 90 °. In addition, the kinetic energy value (KE) of the main peak of C _1s was adjusted to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area, _K.P. E. As a linear base line in the range of 1191 to 1205 eV. In addition, the O _1s peak area is _{expressed as K.I.} E. As a linear base line in the range of 947 to 959 eV. Here, the surface oxygen concentration is 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. As the X-ray photoelectron spectroscopy apparatus, ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. was used, and the sensitivity correction value unique to the apparatus was 2.33.

<Measurement method of sizing adhesion amount>
About 2 g of sizing-attached carbon fiber bundle was weighed (W1) (reading to the fourth decimal place) and then left in an electric furnace (capacity 120 cm3) set at a temperature of 450 ° C. in a nitrogen stream of 50 ml / min for 15 minutes. The sizing agent is completely pyrolyzed. Then, the carbon fiber bundle is transferred to a container in a dry nitrogen stream of 20 liters / minute and cooled for 15 minutes, and the carbon fiber bundle is weighed (W2) (reads up to the fourth decimal place), and the sizing adhesion amount is obtained by W1-W2. . A value obtained by converting this sizing adhesion amount into an amount with respect to 100 parts by mass of the carbon fiber bundle (rounded off to the third decimal place) was defined as a mass part of the adhering sizing agent. The measurement was performed twice, and the average value was defined as the mass part of the sizing agent.

<Measurement of interfacial shear strength (IFSS)>
Interfacial shear strength (IFSS) is measured by the following procedures (a) to (d).
(A) Preparation of resin 100 parts by mass of a bisphenol A type epoxy resin compound “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation) and 14.5 parts by mass of metaphenylenediamine (manufactured by Sigma-Aldrich Japan Co., Ltd.) , Put each in a container. Thereafter, heating is performed at a temperature of 75 ° C. for 15 minutes in order to reduce the viscosity of the jER828 and dissolve the metaphenylenediamine. Then, both are mixed well and vacuum defoaming is performed at a temperature of 80 ° C. for about 15 minutes.
(B) Fixing the carbon fiber single yarn to the special mold Pull out the single fiber from the carbon fiber bundle, and fix both ends with an adhesive in a state where a constant tension is applied to the single fiber in the longitudinal direction of the dumbbell mold. Then, in order to remove the water | moisture content adhering to carbon fiber and a mold, it vacuum-drys for 30 minutes or more at the temperature of 80 degreeC. The dumbbell mold is made of silicone rubber, and the shape of the casting part is a central part width of 5 mm, a length of 25 mm, a both end part width of 10 mm, and an overall length of 150 mm.
(C) From resin casting to curing The resin adjusted in the above procedure (b) is poured into the mold after the vacuum drying in the above step (b), and the temperature rising rate is 1.5 ° C. / The temperature rises to 75 ° C in minutes and is maintained for 2 hours, then the temperature rises to 125 ° C at a temperature rising rate of 1.5 minutes, held for 2 hours, and then lowered to a temperature of 30 ° C at a temperature lowering rate of 2.5 ° C / min. . Then, it demolds and a test piece is obtained.
(D) Measurement of interfacial shear strength (IFSS) A tensile force was applied to the test piece obtained in the above procedure (c) in the fiber axis direction (longitudinal direction) to cause a strain of 12%, and then the test piece was tested with a polarizing microscope. The number of fiber breaks N (pieces) in the range of 22 mm at the center of each piece is measured. Next, the average broken fiber length la is calculated by the formula of la (μm) = 22 × 1000 (μm) / N (pieces). Next, the critical fiber length lc is calculated from the average broken fiber length la by the following formula: lc (μm) = (4/3) × la (μm). The strand tensile strength σ and the diameter d of the carbon fiber single yarn are measured, and the interface shear strength IFSS, which is an index of the bond strength between the carbon fiber and the resin interface, is calculated by the following equation. In the examples, the average of the number of measurements n = 5 was used as the test result.
Interfacial shear strength IFSS (MPa) = σ (MPa) × d (μm) / (2 × lc) (μm).

  The materials and components used in each example and each comparative example are as follows.

-(A1) component: A-1 to A-7
A-1: “jER (registered trademark)” 152 (manufactured by Mitsubishi Chemical Corporation)
Phenol novolac glycidyl ether epoxy equivalent: 175 g / mol, epoxy group number: 3
A-2: “EPICLON (registered trademark)” N660 (manufactured by DIC Corporation)
Cresol novolak glycidyl ether Epoxy equivalent: 206 g / mol, Epoxy group number: 4.3
A-3: “Araldite (registered trademark)” MY721 (manufactured by Huntsman Advanced Materials)
N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane Epoxy equivalent: 113 g / mol, number of epoxy groups: 4
A-4: “jER (registered trademark)” 828 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy equivalent: 189 g / mol, Number of epoxy groups: 2
A-5: “jER (registered trademark)” 1001 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy equivalent: 475 g / mol, Number of epoxy groups: 2
A-6: “Denacol (registered trademark)” EX-810 (manufactured by Nagase ChemteX Corporation)
Diglycidyl ether of ethylene glycol Epoxy equivalent: 113 g / mol, Number of epoxy groups: 2
A-7: TETRAD-X (Mitsubishi Gas Chemical Co., Ltd.)
Tetraglycidyl metaxylenediamine Epoxy equivalent: 100 g / mol, Number of epoxy groups: 4.

・ Applicable to both (A1) component and (A2) component: A-8
A-8: “Denacol (registered trademark)” EX-611 (manufactured by Nagase ChemteX Corporation)
Sorbitol polyglycidyl ether epoxy equivalent: 167 g / mol, number of epoxy groups: 4
Number of hydroxyl groups: 2.

-(A2) component: A-9, A-10
A-9: “Denacol (registered trademark)” EX-731 (manufactured by Nagase ChemteX Corporation)
N-glycidyl phthalimide epoxy equivalent: 216 g / mol, number of epoxy groups: 1
Number of imide groups: 1
A-10: “Adeka Resin (registered trademark)” EPU-6 (manufactured by ADEKA Corporation)
Urethane-modified epoxy Epoxy equivalent: 250 g / mol, number of epoxy groups: 1 or more Urethane group: 1 or more.

-(B) component: B-1 to B-4
B-1: TINUVIN765 (manufactured by BASF)
Bis sebacate (1,2,2,6,6-pentamethyl-4-piperidyl)
B-2: LA-52 (made by ADEKA)
Butane-1,2,3,4-tetracarboxylic acid tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl)
B-3: 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (manufactured by Tokyo Chemical Industry Co., Ltd.)
B-4: 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (manufactured by Wako Pure Chemical Industries, Ltd.).

Example 1
The present example includes the following first step and second step.
Step I: Process for producing carbon fiber as raw material A copolymer composed of 99 mol% of allylonitrile and 1 mol% of itaconic acid is spun and fired, the total number of filaments is 24,000, and the total fineness is 1. Carbon fiber having 1,000 tex, specific gravity of 1.8, strand tensile strength of 6.2 GPa and strand tensile modulus of 300 GPa was obtained. Subsequently, the carbon fiber was subjected to an electrolytic surface treatment using an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / l as an electrolytic solution at an electric charge of 100 coulomb per 1 g of the carbon fiber. The carbon fiber subjected to the electrolytic surface treatment was subsequently washed with water and dried in heated air at a temperature of 150 ° C. to obtain a carbon fiber as a raw material. At this time, the surface oxygen concentration O / C was 0.20. This was designated as carbon fiber A.
Step II: A step of attaching a sizing agent to carbon fibers The above (A-1) and (B-1) are mixed at a mass ratio of 100: 1, and acetone is further mixed, so that the sizing agent is uniform. An acetone solution of about 1% by mass dissolved in was obtained. Using an acetone solution of this sizing agent, the sizing agent was applied to the surface-treated carbon fiber by a dipping method, followed by heat treatment at a temperature of 200 ° C. for 120 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, interfacial shear strength (IFSS) was measured using the obtained sizing agent-coated carbon fibers. The results are summarized in Table 1. As a result, it was found that IFSS was 38 MPa and the adhesiveness was sufficiently high.

(Examples 2 to 5)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
-Step II: Step of attaching sizing agent to carbon fiber In step II of Example 1, as shown in Table 1, the mass ratio of (A-1) and (B-1) is 100: 3 A sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except that it was changed within the range of ˜100: 20. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, as a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fiber, it was found that IFSS was 36 to 40 MPa, and all had sufficiently high adhesion. Especially, when the mass ratio of (A-1) and (B-1) was 100: 3 and 100: 6, the adhesiveness was extremely excellent. The results are shown in Table 1.

(Comparative Example 1)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon in the same manner as in Example 1 except that only (A-1) was used in Step II of Example 1. Fiber was obtained. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, interfacial shear strength (IFSS) was measured using the obtained sizing agent-coated carbon fiber, and as a result, it was found that IFSS was 25 MPa and adhesion was insufficient. The results are shown in Table 1.

(Comparative Example 2)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
-Step II: Step of attaching sizing agent to carbon fiber In Step II of Example 1, except that the mass ratio of (A-1) and (B-1) was changed to 100: 30, Sizing agent-coated carbon fibers were obtained in the same manner as in Example 1. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, as a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fiber, it was found that IFSS was 20 MPa and adhesion was insufficient. The results are shown in Table 1.

(Examples 6 to 14)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
-Step II: Step of attaching sizing agent to carbon fiber As shown in Table 2, the components (A) are (A-2) to (A-10) and the component (B) is (B-1). A carbon fiber coated with a sizing agent was obtained in the same manner as in Example 1 except that. The adhesion amount of the sizing agent was 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, as a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fibers, it was found that IFSS was 32 to 38 MPa, and all had sufficiently high adhesion. The results are shown in Table 3.

(Comparative Examples 3-6)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
-Step II: Step of attaching sizing agent to carbon fiber As shown in Table 2, only (A-4), (A-8) only, (A-9) only, (A-10) only A sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except that it was used. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, as a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fiber, it was found that IFSS was 23 to 27 MPa and adhesion was insufficient. The results are shown in Table 3.

(Examples 15 to 17)
-Step I: Step of producing carbon fiber as a raw material The same as in Example 1.
Step II: Step of attaching sizing agent to carbon fiber As shown in Table 3, (A) as component (A-1), (B) as components (B-2) to (B-4) A sizing agent-coated carbon fiber was obtained in the same manner as in Example 1 except for the change. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. Subsequently, interfacial shear strength (IFSS) was measured using the obtained sizing agent-coated carbon fibers. The results are summarized in Table 3. As a result, it was found that IFSS was 38 to 41 MPa, and adhesion was sufficiently high.

(Example 18)
-Step I: Step of producing carbon fiber as raw material Implemented except that sulfuric acid aqueous solution having a concentration of 0.05 mol / l was used as the electrolytic solution, and the amount of electricity was subjected to electrolytic surface treatment at 20 coulomb per gram of carbon fiber. Same as Example 1. At this time, the surface oxygen concentration O / C was 0.20. This was designated as carbon fiber B.
-Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 6. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. As a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fiber, it was found that IFSS was 34 MPa and the adhesiveness was sufficiently high. The results are shown in Table 3.

(Example 19)
-Step I: Step of producing carbon fiber as raw material The carbon fiber B obtained in Example 18 was immersed in a tetraethylammonium hydroxide aqueous solution (pH = 14) and pulled up while being vibrated with ultrasonic waves. At this time, the surface oxygen concentration O / C was 0.17. This was designated as carbon fiber C.
-Step II: Step of attaching sizing agent to carbon fiber Sizing agent-coated carbon fiber was obtained in the same manner as in Example 6. The adhesion amount of the sizing agent was adjusted to 1 part by mass with respect to 100 parts by mass of the surface-treated carbon fiber. As a result of measuring the interfacial shear strength (IFSS) using the obtained sizing agent-coated carbon fiber, it was found that IFSS was 37 MPa and the adhesiveness was sufficiently high. The results are shown in Table 3.

Claims (5)

As the component (A), (A1) an epoxy compound having two or more epoxy groups, and / or (A2) one or more epoxy groups, an unsaturated group, a hydroxyl group, an amide group, an imide group, a urethane group, 100 parts by mass of an epoxy compound having at least one functional group selected from a urea group, a sulfonyl group, and a sulfo group, and as the component (B), a hindered amine compound 0.1 to the following general formula (I) A sizing agent-coated carbon fiber to which a sizing agent comprising 25 parts by mass is adhered.

(Wherein R ₁ represents a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, the hydrocarbon group may have a hydroxyl group, and the CH ₂ group in the hydrocarbon group is —O— , —O—CO— or —CO—O— may be substituted, and R ₂ represents hydrogen, a hydroxyl group or a hydrocarbon group having 1 to 22 carbon atoms, and the hydrocarbon group has a hydroxyl group. And the CH ₂ group in the hydrocarbon group may be substituted by —O—, —O—CO— or —CO—O—.) Sizing agent application | coating carbon fiber of Claim 1 whose epoxy equivalent of the epoxy compound of (A) component is less than 360 g / mol. Sizing agent application | coating carbon fiber in any one of Claim 1 or 2 whose epoxy compound of (A) component contains an aromatic ring in a molecule | numerator. Sizing agent application | coating carbon fiber in any one of Claims 1-3 whose epoxy compound of (A) component is either a phenol novolak-type epoxy resin, a cresol novolak-type epoxy resin, or tetraglycidyl diamino diphenylmethane. Sizing agent application | coating carbon fiber in any one of Claims 1-4 whose surface oxygen concentration O / C measured by the X ray photoelectron spectroscopy of carbon fiber is 0.05-0.5.