JP2015007300A - Sizing agent-coated carbon fibers, method for producing the same, and carbon fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sizing agent-coated carbon fibers excellent in adhesion to a matrix resin and handleability, a method for producing sizing agent-coated carbon fibers, and a carbon fiber-reinforced composite material.SOLUTION: The sizing agent-coated carbon fibers of the present invention are obtained by applying a sizing agent which contains at least an aliphatic epoxy compound (A) having an epoxy equivalent of 360 g/eq. or less and a compound (B) having a terminal unsaturated group and a polar group in one molecule to carbon fibers at a mass ratio (A)/(B) of 30/70-70/30.

Description

  The present invention relates to a sizing agent-coated carbon fiber, a method for producing the sizing agent-coated carbon fiber, and a carbon fiber reinforced composite material. More specifically, the present invention relates to a sizing agent-coated carbon fiber excellent in stability over time, and particularly to a sizing agent-coated carbon fiber excellent in adhesiveness to an unsaturated matrix resin, and a carbon fiber reinforced composite material.

  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.

  A composite material of carbon fibers and a matrix resin is manufactured by impregnating a resin by making carbon fibers into a woven fabric or a sheet in which a plurality of them are arranged in parallel. If the carbon fiber is mechanically opened using a carbon fiber that is rigid and has poor openability as this carbon fiber, the carbon fiber in the fiber bundle is cut and fluff is formed, or the fiber bundle is broken and the process passability is reduced. There was a problem to do. When fabrics and sheets are created using the carbon fibers, the fibers do not spread in the width direction, so that gaps remain between the carbon fiber bundles, and the physical properties of the obtained carbon fiber reinforced composite material are also reduced. There was also a problem.

  Therefore, the sizing agent imparts adhesion between the carbon fiber and the resin, spreadability of the carbon fiber, and convergence.

  For example, there is one that provides a specific sizing agent and defines a drape value that is an index of the hardness of the carbon fiber (Patent Document 1).

  Moreover, the compound which has several aliphatic type epoxy groups as a sizing agent is proposed (refer patent document 2, 3, 4). In addition, a method of applying an epoxy adduct of polyalkylene glycol as a sizing agent to carbon fibers has been proposed (see Patent Documents 5, 6 and 7).

  In addition, a method of applying diglycidyl ether of bisphenol A to carbon fibers as an aromatic sizing agent has been proposed (see Patent Documents 8 and 9). 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 10 and 11). In addition, a method of applying a bisphenol A polyalkylene oxide adduct having an epoxy group added thereto to a carbon fiber as a sizing agent has been proposed (see Patent Documents 12 and 13).

  Although the above-described sizing agent can impart handling properties such as adhesion and spreadability to the carbon fiber, it cannot be said that it is sufficient from the viewpoint of both compatibility.

  In addition to epoxy resins, the demand for thermosetting resins such as unsaturated polyester resins, phenol resins, and vinyl esters is increasing for matrix resins of carbon fiber reinforced composite materials. In particular, carbon fiber reinforced composite materials with unsaturated polyester resins and vinyl ester resins, which are used in small vessels, boats, yachts, fishing boats, septic tanks, various tanks, etc., have a short molding cycle and low molding costs, are important. Yes. In the case of such a matrix resin, the epoxy resin-based sizing agent described above has a problem that the familiarity between the carbon fiber and the unsaturated polyester or vinyl ester is lower than that of the epoxy resin, and the adhesive property is low. .

  Therefore, a technique for improving the adhesion between the carbon fiber and the unsaturated polyester resin and improving the adhesion is disclosed. For example, an ester compound having a terminal unsaturated group (Patent Document 14) has been proposed, and the adhesion between carbon fiber and unsaturated polyester resin is improved by providing the sizing agent as a coupling agent with a matrix resin. It is described to do. In addition to terminal unsaturated groups, it is described that a compound having a polar group in one molecule (Patent Document 15) is provided to enhance the interaction with carbon fibers. There is no mention of controlling the hardness of carbon fibers for improving handling properties such as fineness.

  Further, improvement in handling properties such as adhesion and spreadability by combining two or more compounds has been proposed. Disclosed is an ester of an epoxy compound having a plurality of epoxy groups in the molecule and an unsaturated monobasic acid, a compound having at least one epoxy group in the molecule, a bifunctional urethane acrylate oligomer, and polyurethane. (Patent Document 16).

  However, in terms of handling properties such as high adhesiveness with a matrix resin having an unsaturated bond and openability, the actual situation is that a sizing agent in which two or more kinds are mixed is not sufficient. The reason is that in order to satisfy both high adhesiveness and high handling properties at the same time, it is considered necessary to have a sizing layer gradient structure in order to satisfy the following three requirements. It can be said that it was not satisfied. The first of the three requirements is that there is an epoxy component with high adhesiveness inside the sizing layer (carbon fiber side), and the carbon fiber and the epoxy compound in the sizing agent interact strongly. However, in order to improve the adhesion to the matrix resin, the sizing layer surface layer (matrix resin side) has a chemical composition capable of strong interaction with the matrix resin, and the third is the sizing agent In order to suppress curing and to suppress diffusion to the matrix resin, there may be a specific ratio of an epoxy component with high adhesion and a component capable of strong interaction with the matrix resin on the sizing agent surface layer (matrix resin side). is necessary.

  For example, Patent Document 17 discloses that the sizing agent has an inclined structure in order to enhance the adhesion between the carbon fiber and the sizing agent, but the high adhesion with the matrix resin having an unsaturated bond is disclosed. There is no idea to satisfy the handling properties such as high fiber opening at the same time, and the combination of compounds is also different.

JP 2005-264383 A Japanese Examined Patent Publication No. 63-14114 JP-A-7-279040 JP-A-8-113876 JP-A-57-128266 U.S. Pat. No. 4,555,446 JP 62-033872 A US Pat. No. 3,957,716 JP-A-57-171767 Japanese Unexamined Patent Publication No. 7-009444 JP 2000-336577 A JP 61-028074 A JP-A-1-272867 JP 63-105178 A Japanese Patent Laid-Open No. 11-93078 International Publication No. 2013/027708 JP 2005-179828 A

  The present invention has been made in view of the above, and provides a sizing agent-coated carbon fiber that is excellent in handleability of sizing agent-coated carbon fibers, and particularly excellent in adhesion when combined with a radical polymerization resin. The purpose is to do.

  The present inventors have found that the above-described object can be achieved in a sizing agent-coated carbon fiber using a sizing agent in which a plurality of specific compounds are combined at a specific ratio. That is, in the present invention, a known sizing agent can be used as each sizing agent itself, but combining a specific compound at a specific ratio is an important sizing method, and is a novel one. It can be said that there is.

  The inventors have an epoxy equivalent of 360 g / eq. A step of applying to a carbon fiber a sizing agent containing a specific proportion of the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule, and carbon fiber coated with the sizing agent Thus, the present inventors have found that the adhesion between the carbon fiber and the matrix resin is good and that the sizing agent-coated carbon fiber is hard to be hard and has excellent handleability, and thus has come to the present invention.

  In the present invention, at least the epoxy equivalent is 360 g / eq. A sizing agent containing the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule has a mass ratio of (A) / (B) of 30/70 to 70/30. It is characterized by being a sizing agent-coated carbon fiber coated on carbon fiber at a ratio.

  In the sizing agent-coated carbon fiber of the present invention, in the above invention, the compound (A) is one selected from glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol; It is a glycidyl ether type epoxy compound obtained by a reaction with chlorohydrin.

  The sizing agent-coated carbon fiber of the present invention is characterized in that, in the above-mentioned invention, the terminal unsaturated group is selected from a vinyl group, an acrylate group, and a methacrylate group.

  The sizing agent-coated carbon fiber of the present invention is characterized in that, in the above invention, the polar group is selected from an amide bond, an imide bond, a urethane bond, a urea bond, an isocyanate group, and a sulfo group. To do.

  The sizing agent-coated carbon fiber of the present invention is characterized in that, in the above invention, the compound (B) has four terminal unsaturated groups in one molecule.

  Further, the sizing agent-coated carbon fiber of the present invention is the surface oxygen which is the ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured by X-ray photoelectron spectroscopy of the carbon fiber in the above invention. The concentration (O / C) is 0.10 or more.

  Moreover, the manufacturing method of the sizing agent application | coating carbon fiber of this invention is the said invention. WHEREIN: At least epoxy equivalent is 360 g / eq. After applying the following aliphatic epoxy compound (A) and a sizing agent aqueous solution containing a compound (B) having a terminal unsaturated group and a polar group in one molecule, heat treatment is performed at a temperature range of 160 to 260 ° C. for 30 to 600 seconds. Including the step of:

  Moreover, the carbon fiber reinforced composite material of the present invention is a sizing agent produced by the method for producing a sizing agent-coated carbon fiber according to any one of the above, and a sizing agent-coated carbon fiber according to any one of the above. It consists of coated carbon fiber and a resin mainly composed of vinyl ester resin or unsaturated polyester resin.

  The carbon fiber reinforced composite material of the present invention is characterized in that, in the above invention, the sizing agent-coated carbon fiber is used in the form of a woven fabric or a sheet-like material aligned in one direction.

  According to the present invention, it is possible to obtain a sizing agent-coated carbon fiber that is excellent in handling of the sizing agent-coated carbon fiber and excellent in adhesion to a matrix resin, particularly a radical polymerization resin. Moreover, the physical properties of the carbon fiber reinforced composite material using the sizing agent-coated carbon fiber are also improved.

It is a conceptual diagram which shows the measuring method of a drape value.

  Hereinafter, the sizing agent-coated carbon fiber of the present invention will be described in more detail.

  The sizing agent-coated carbon fiber of the present invention has at least an epoxy equivalent of 360 g / eq. A sizing agent containing the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule has a mass ratio of (A) / (B) of 30/70 to 70/30. It is characterized by being applied to the carbon fiber at a ratio.

  First, the sizing agent used in the present invention has at least an epoxy equivalent of 360 g / eq. A sizing agent containing the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule is included.

  In the present invention, the epoxy equivalent is 360 g / eq. When the following aliphatic epoxy compound (A) and the compound (B) having a terminal unsaturated group and a polar group in one molecule are used in combination, a more polar epoxy equivalent is 360 g / eq. The following aliphatic epoxy compound (A) is unevenly distributed on the carbon fiber side, and the compound (B) having a terminal unsaturated group and a polar group in one molecule having low polarity in the outermost layer of the sizing layer opposite to the carbon fiber There is a phenomenon that is ubiquitous. As a result of the gradient structure of the sizing layer, the sizing agent-coated carbon fiber according to the present invention has an epoxy equivalent of 360 g / eq. On the inner side (carbon fiber side) of the sizing layer. Many of the following aliphatic epoxy compounds (A) are present, and many compounds (B) having terminal unsaturated groups and polar groups are present in one molecule on the sizing layer surface layer (matrix resin side). The epoxy equivalent which exists abundantly inside the sizing layer is 360 g / eq. The following aliphatic epoxy compounds (A) interact strongly with carbon fibers and enhance adhesion. When the sizing agent-coated carbon fiber of the present invention is used for a carbon fiber reinforced composite material, the compound (B) having a terminal unsaturated group and a polar group in one molecule that is present in a large amount in the surface layer of the sizing layer is also strong with the matrix resin. It becomes possible to have an interaction.

  The sizing agent has an epoxy equivalent of 360 g / eq. The carbon fiber coated with the sizing agent is composed of the following aliphatic epoxy compound (A) only and does not contain the compound (B) having a terminal unsaturated group and a polar group in one molecule. It has been confirmed that the interaction is high. The mechanism is not certain, but the epoxy equivalent is 360 g / eq. The following aliphatic epoxy compound (A) has a sufficient interaction with a functional group with a carboxyl group and a hydroxyl group on the surface of the carbon fiber, and is derived from a flexible skeleton and a structure having a high degree of freedom. Surface functional group and epoxy equivalent were 360 g / eq. It is considered that the following aliphatic epoxy compound (A) can form a strong interaction. The sizing agent of the present invention has an epoxy equivalent of 360 g / eq. Compared to the case where only the following aliphatic epoxy compound (A) is used, when a radical polymerization resin such as vinyl ester resin or unsaturated polyester resin is used for the matrix resin, the epoxy compound of the sizing agent is used as the matrix resin. Can form strong interaction and improve adhesion.

  The sizing agent comprises a compound (B) having a terminal unsaturated group and a polar group in one molecule, and an epoxy equivalent is 360 g / eq. When the following aliphatic epoxy compound (A) is not included, the carbon fiber coated with the sizing agent interacts with the carbon fiber and the sizing agent due to the affinity of the carbon fiber functional group and the polar group of the sizing agent. Since the saturated group can form a covalent bond or the like with the unsaturated group in the matrix resin, the adhesiveness is increased. However, since this compound (B) suppresses diffusion at the time of molding the composite, it is necessary to form a film on the carbon fiber surface, and after applying a sizing agent to the carbon fiber surface, it is necessary to increase the molecular weight by heat treatment. Compared to film formation of the compound (B) having a terminal unsaturated group and a polar group in one molecule, the epoxy equivalent is 360 g / eq. Since the temperature at which the following interaction between the aliphatic epoxy compound (A) and the carbon fiber is formed is low, high adhesiveness can be maintained from a low temperature during sizing of the present invention. As a result, the sizing agent-coated carbon fiber is difficult to be hardened, so that the handleability is improved.

  Note that the surface layer of the sizing layer is not a compound (B) having a terminal unsaturated group and a polar group in one molecule, but an epoxy equivalent of 360 g / eq. The presence of the following aliphatic epoxy compound (A) in a predetermined ratio can reduce the density of unsaturated groups on the surface of the sizing agent, and a compound having a terminal unsaturated group and a polar group in one molecule (B ) Can be suppressed from diffusing into the matrix resin, and high adhesiveness can be obtained from a low heat treatment temperature. As a result, it is possible to suppress the sizing agent-coated carbon fiber from becoming hard. Further, even when the sizing agent-coated carbon fiber is stored for a long period of time, the reaction of the terminal unsaturated group contained in the compound (B) having a terminal unsaturated group and a polar group in one molecule can be suppressed, and the sizing agent-coated carbon It can suppress that a fiber becomes hard. Moreover, the interaction between the carbon fiber and the matrix resin can be enhanced by changing the composition of the sizing layer in an inclined manner from the inside of the sizing layer to the surface layer.

  The sizing agent in the present invention has an epoxy equivalent of 360 g / eq. The mass ratio (A) / (B) of the following aliphatic epoxy compound (A) and the compound (B) having a terminal unsaturated group and a polar group in one molecule is 30/70 to 70/30. By setting (A) / (B) to 30/70 or more, the epoxy equivalent sufficient for the carbon fiber surface is 360 g / eq. The following aliphatic epoxy compound (A) exists and the interaction between the carbon fiber and the sizing agent is increased. As a result, composite properties such as tensile strength of the obtained carbon fiber reinforced composite material are enhanced. Further, by setting (A) / (B) to 70/30 or less, the terminal unsaturated groups capable of interacting with the matrix resin increase in the surface layer of the sizing agent, and the adhesiveness to the resin is improved. The mass ratio of (A) / (B) is preferably 40/60 or more, and more preferably 45/55 or more. The mass ratio of (A) / (B) is preferably 65/35 or less, and more preferably 60/30 or less.

  The sizing agent according to the present invention has an epoxy equivalent of 360 g / eq. With respect to the total amount of the sizing agent excluding the solvent. It is preferable that 15 mass% or more of the following aliphatic epoxy compounds (A) are included, and it is preferable that 40 mass% or more is included.

  The epoxy equivalent used in the present invention is 360 g / eq. The following aliphatic epoxy compounds (A) are epoxy compounds that do not contain an aromatic ring. Since it has a flexible skeleton with a high degree of freedom, it can have a strong interaction with carbon fibers. As a result, the adhesion between the carbon fiber coated with the sizing agent and the matrix resin is improved. Moreover, even if it is compared with the compound (B) which has a terminal unsaturated group and a polar group in one molecule, it has high polarity and can be unevenly distributed on the carbon fiber side.

  In the present invention, the epoxy equivalent is 360 g / eq. The following aliphatic epoxy compounds (A) have one or more epoxy groups in the molecule. As a result, a strong bond between the carbon fiber and the epoxy group in the sizing agent can be formed. The number of epoxy groups in the molecule is preferably 2 or more, and more preferably 3 or more. Epoxy equivalent is 360 g / eq. When the following aliphatic epoxy compound (A) is an epoxy compound having two or more epoxy groups in the molecule, even when one epoxy group forms a covalent bond with an oxygen-containing functional group on the surface of the carbon fiber The remaining epoxy groups can form a covalent bond or a hydrogen bond with the matrix resin, and the adhesion can be further improved. There is no particular upper limit on the number of epoxy groups, but 10 is sufficient from the viewpoint of adhesion.

  In the present invention, the epoxy equivalent is 360 g / eq. The following aliphatic epoxy compound (A) is preferably an epoxy compound having 3 or more of 2 or more types of functional groups, and more preferably an epoxy compound having 4 or more of 2 or more types of 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. Epoxy equivalent is 360 g / eq. When the following aliphatic epoxy compound (A) is an epoxy compound having three or more epoxy groups or other functional groups in the molecule, one epoxy group is covalently bonded to an oxygen-containing functional group on the surface of the carbon fiber. Even in the case of forming, 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 functional groups containing an epoxy group, but 10 is sufficient from the viewpoint of adhesiveness.

  The epoxy equivalent of the aliphatic epoxy compound (A) used in the present invention is 360 g / eq. It is as follows. More preferably, 270 g / eq. Or less, more preferably 180 g / eq. It is as follows. Compound (B) having a terminal unsaturated group and a polar group in one molecule because the interaction with carbon fiber is formed at high density, the adhesion between carbon fiber and matrix resin is further improved, and the polarity is increased Compared to the carbon fiber side, the epoxy equivalent of the aliphatic epoxy compound (A) is 360 g / eq. It is necessary that: There is no particular lower limit of epoxy equivalent, but 90 g / eq. The above is sufficient from the viewpoint of adhesiveness.

  In the present invention, the epoxy equivalent is 360 g / eq. Specific examples of the following aliphatic epoxy compounds (A) include, for example, glycidyl ether type epoxy compounds derived from polyols, glycidyl amine type epoxy compounds derived from amines having multiple active hydrogens, and polycarboxylic acids. And an epoxy compound obtained by oxidizing a compound having a plurality of double bonds in the molecule.

  Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound obtained by a reaction between a polyol and epichlorohydrin. For example, as a glycidyl ether type epoxy compound, 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, Pentaerythritol, sorbitol and one and selected from arabitol, glycidyl ether type epoxy compound obtained by reaction with epichlorohydrin. Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound having a dicyclopentadiene skeleton.

  Examples of the glycidylamine type epoxy compound include 1,3-bis (aminomethyl) cyclohexane.

  Examples of the glycidyl ester type epoxy compound include a glycidyl ester type epoxy compound obtained by reacting dimer acid with epichlorohydrin.

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

  The epoxy equivalent used in the present invention is 360 g / eq. In addition to these epoxy compounds, the following aliphatic epoxy compounds (A) include epoxy compounds such as triglycidyl isocyanurate.

  The epoxy equivalent according to the present invention is 360 g / eq. The following aliphatic epoxy compound (A) is at least one selected from one or more epoxy groups and a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, an ester group, and a sulfo group. It preferably has at least one functional group. Epoxy equivalent is 360 g / eq. Specific examples of the functional group possessed by the following aliphatic epoxy compound (A) include, for example, 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 and a urethane. A compound having a group, a compound having an epoxy group and a urea group, a compound having an epoxy group and a sulfonyl group, and a compound having an epoxy group and a sulfo group.

  The epoxy equivalent having a hydroxyl group in addition to the epoxy group is 360 g / eq. Examples of the aliphatic epoxy compound (A) 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).

  Epoxy equivalent having an amide group in addition to the epoxy group is 360 g / eq. Examples of the following aliphatic epoxy compound (A) include amide-modified epoxy compounds. The amide-modified epoxy can be obtained by reacting an epoxy group of an epoxy compound having two or more epoxy groups with a carboxyl group of an aliphatic dicarboxylic acid amide.

  Epoxy equivalent used in the present invention is 360 g / eq. The following aliphatic epoxy compounds (A) are ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene from the viewpoint of high adhesiveness as described above. Glycol, polypropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, polybutylene glycol, 1,5-pentanediol, neopentyl Selected from glycol, 1,6-hexanediol, glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol One and is, glycidyl ether type epoxy compound obtained by the reaction of epichlorohydrin are preferred.

  In the present invention, the epoxy equivalent is 360 g / eq. The following aliphatic epoxy compound (A) is a glycidyl ether obtained by reacting one kind selected from glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol with epichlorohydrin It is more preferable that it is a type epoxy compound, and polyglycerol polyglycidyl ether is more preferable.

  The compound (B) used in the present invention has a terminal unsaturated group and a polar group in one molecule.

  The terminal unsaturated group is preferably selected from a vinyl group, an acrylate group, and a methacrylate group. The polar group is preferably selected from an amide bond, an imide bond, a urethane bond, a urea bond, an isocyanate group, and a sulfo group.

  The number of terminal unsaturated groups per molecule is preferably 2 or more. By being two or more, when the terminal unsaturated groups condense in the drying and heat treatment process after application of the sizing agent to increase the molecular weight, the remaining terminal unsaturated groups react with the matrix resin to adhere. Increases nature. The number of terminal unsaturated groups per molecule is preferably 3 or more, more preferably 4 or more. In addition, even when the sizing agent-coated carbon fibers are stored for a long period of time with 8 or less, it is preferable because curing can be suppressed.

The number of polar groups per molecular weight should be 1 × 10 ⁻³ or more in order to ensure the interaction of the polar groups with a specific amount of carbon fiber surface functional groups when filmed on the carbon fiber surface. Preferably, it is 3 × 10 ⁻³ or more.

  In addition, the compound having a polar group and a terminal unsaturated group in the present invention includes a compound obtained by reacting an unsaturated alcohol, an unsaturated carboxylic acid and an isocyanate compound. Examples of the unsaturated alcohol include allyl alcohol and unsaturated compounds. Examples of the carboxylic acid include acrylic acid and methacrylic acid, and examples of the isocyanate compound include known unsaturated polyurethane compounds such as hexamethylene disisocyanate, isophorone diisocyanate, tolylene diisocyanate, ditolylene diisocyanate, and diphenylmethane diisocyanate.

  In particular, a compound in which the unsaturated terminal group of the unsaturated polyurethane compound is an acrylate group and a methacrylate group is preferable. Phenyl glycidyl ether acrylate hexamethylene diisocyanate compound, phenyl glycidyl ether acrylate tolylene diisocyanate compound, pentaerythritol acrylate hexamethylene diisocyanate compound, phenyl Glycidyl ether triacrylate isophorone diisocyanate compound, glycerin dimethacrylate tolylene diisocyanate compound, glycerin dimethacrylate isophorone diisocyanate compound, pentaerythritol triacrylate tolylene diisocyanate compound, pentaerythritol triacrylate isophorone diisocyanate, triallyl isocyanate At least one compound selected from the rate compound.

  Examples of the compound having an amide bond and a terminal unsaturated group include N, N-dimethylacrylamide, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N, N- Examples include diethyl acrylamide. Examples of the compound having a sulfo group and a terminal unsaturated group include bisphenol S-type diglycidyl diacrylate and bisphenol S-type diglycidyl dimethacrylate.

  A preferred sizing agent has a structure in which a molecular chain is linear and flexible, particularly an aliphatic polyisocyanate compound having a terminal unsaturated group and a polar group, that is, a polyisocyanate having a polyethylene glycol skeleton and a polyalkylene skeleton. Compounds are preferred.

  The molecular weight of the compound is preferably 300 or more and 2000 or less, and more preferably 500 or more and 1000 or less, from the viewpoint of preventing the resin viscosity from increasing and handling properties as a sizing agent from being deteriorated.

  Furthermore, the sizing agent used in the present invention has an epoxy equivalent of 360 g / eq. One or more components other than the above aliphatic epoxy compound (A) and the compound (B) having a terminal unsaturated group and a polar group in one molecule may be contained. It is preferable to add a material that imparts convergence or flexibility to the sizing agent-coated carbon fiber because handling properties can be further improved, and scratch resistance and fluff resistance can be increased.

  In the present invention, the epoxy equivalent is 360 g / eq. As an epoxy compound other than the aliphatic epoxy compound (A), the epoxy equivalent is 360 g / eq. Less than aliphatic epoxy compounds and aromatic epoxy compounds can be used.

  Aromatic epoxy compounds contain one or more epoxy groups and aromatic rings in the molecule. The aromatic ring may be an aromatic ring hydrocarbon consisting only of carbon, or a heteroaromatic ring such as furan, thiophene, pyrrole or imidazole containing a heteroatom such as nitrogen or oxygen. The aromatic ring may be a polycyclic aromatic ring such as naphthalene or anthracene. Due to the hydrophobicity of the aromatic ring, the epoxy equivalent is 360 g / eq. Since the interaction with the carbon fiber is weaker than the following aliphatic epoxy compound (A), the interaction with the carbon fiber is low, resulting in the presence of many aromatic compounds in the outer layer of the sizing layer. It is preferable to use an aromatic compound because scratch resistance is improved.

  In the present invention, specific examples of the aromatic epoxy compound include, for example, a glycidyl ether type epoxy compound derived from an aromatic polyol, a glycidyl amine type epoxy compound derived from an aromatic amine having a plurality of active hydrogens, and an aromatic poly Examples thereof include glycidyl ester type epoxy compounds derived from carboxylic acids and epoxy compounds obtained by oxidizing aromatic compounds having a plurality of double bonds in the molecule.

  Examples of the glycidyl ether type epoxy compound include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetrabromobisphenol A, phenol novolac, cresol novolac, hydroquinone, resorcinol, 4,4′-dihydroxy-3,3 ′, 5. , 5′-tetramethylbiphenyl, 1,6-dihydroxynaphthalene, 9,9-bis (4-hydroxyphenyl) fluorene, tris (p-hydroxyphenyl) methane, and tetrakis (p-hydroxyphenyl) ethane The glycidyl ether type epoxy compound obtained by reaction with 1 type and epichlorohydrin is mentioned. Examples of the glycidyl ether type epoxy compound include a glycidyl ether type epoxy compound having a biphenylaralkyl skeleton.

  Examples of the glycidylamine type epoxy compound include N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, m-xylylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane and 9 , 9-bis (4-aminophenyl) fluorene, and a glycidyl ether type epoxy compound obtained by reaction with epichlorohydrin.

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

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

  As an aromatic epoxy compound used in the present invention, in addition to these epoxy compounds, epoxy compounds synthesized from the above-mentioned epoxy compounds, for example, oxazolidone ring formation reaction from bisphenol A diglycidyl ether and tolylene diisocyanate An epoxy compound synthesized by the method can be given.

  In the present invention, the aromatic epoxy compound is selected from a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, an ester group and a sulfo group, in addition to one or more epoxy groups. One or more functional groups are preferably used. For example, compounds having epoxy group and hydroxyl group, compounds having epoxy group and amide group, compounds having epoxy group and imide group, compounds having epoxy group and urethane group, compounds having epoxy group and urea group, epoxy group and sulfonyl Examples thereof include compounds having a group and compounds having an epoxy group and a sulfo group.

  Examples of the aromatic epoxy compound having an amide group in addition to the epoxy group include glycidylbenzamide and amide-modified epoxy compounds. The amide-modified epoxy can be obtained by reacting an epoxy group of an epoxy compound having two or more epoxy groups with a carboxyl group of a dicarboxylic acid amide containing an aromatic ring.

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

  As an aromatic epoxy compound having a urethane group in addition to an epoxy group, the terminal hydroxyl group of the polyethylene oxide monoalkyl ether is reacted with a polyvalent isocyanate containing an aromatic ring having a reaction equivalent to the amount of the hydroxyl group, and then the reaction obtained It can be obtained by reacting the isocyanate residue of the product with a hydroxyl group in the polyvalent epoxy compound. Here, examples of the polyvalent isocyanate used include 2,4-tolylene diisocyanate, metaphenylene diisocyanate, paraphenylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and biphenyl-2,4,4′-triisocyanate. It is done.

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

  Examples of the aromatic epoxy compound having a sulfonyl group in addition to the epoxy group include bisphenol S-type epoxy.

  Examples of the aromatic epoxy compound having a sulfo group in addition to the epoxy group include glycidyl p-toluenesulfonate and glycidyl 3-nitrobenzenesulfonate.

  In the present invention, the aromatic epoxy compound is a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, tetraglycidyl diaminodiphenylmethane, a bisphenol A type epoxy compound or a bisphenol F type epoxy compound. From the viewpoint, it is preferably a bisphenol A type epoxy compound or a bisphenol F type epoxy compound.

  In addition to the above, ester compounds and urethane compounds are preferably used.

  The ester compound may be an aliphatic ester compound having no aromatic ring, or may be an aromatic ester compound having one or more aromatic rings in the molecule. It is preferable to use an aromatic ester compound as the ester compound because the rub resistance of the sizing agent-coated carbon fiber is improved. In particular, since the aromatic ester compound has a weak interaction with the carbon fiber, it exists in the outer layer of the matrix resin, and it is possible to improve the scratch resistance while suppressing a decrease in adhesiveness. In addition to the ester group, the aromatic ester compound has a functional group other than an epoxy group, such as a hydroxyl group, an amide group, an imide group, a urethane group, a urea group, a sulfonyl group, a carboxyl group, and a sulfo group. May be. Specifically, it is preferable to use an ester compound composed of a condensate of an alkylene oxide adduct of bisphenols and an unsaturated dibasic acid as the aromatic ester compound. The unsaturated dibasic acid includes an acid anhydride lower alkyl ester, and fumaric acid, maleic acid, citraconic acid, itaconic acid and the like are preferably used. As the alkylene oxide adducts of bisphenols, ethylene oxide adducts, propylene oxide adducts, butylene oxide adducts of bisphenol are preferably used. Among the condensates, a condensate of fumaric acid or maleic acid and bisphenol A ethylene oxide or / and propylene oxide adduct is preferably used.

  The method for adding alkylene oxide to bisphenols is not limited, and known methods can be used. If necessary, a saturated dibasic acid or a small amount of a monobasic acid can be added to the unsaturated dibasic acid as long as the properties such as adhesiveness are not impaired. Further, ordinary glycols, polyether glycols and small amounts of polyhydric alcohols and monohydric alcohols can be added to the alkylene oxide adducts of bisphenols as long as the properties such as adhesiveness are not impaired. A known method can be used as the condensation method of the alkylene oxide adduct of bisphenol and the unsaturated dibasic acid.

  The urethane compound may be an aliphatic urethane compound having no aromatic ring, or may be an aromatic urethane compound having one or more aromatic rings in the molecule. It is preferable to use an aromatic urethane compound as the urethane compound because the scratch resistance of the sizing agent-coated carbon fiber is improved. In particular, since the aromatic urethane compound has a weak interaction with the carbon fiber, it exists in the outer layer of the matrix resin, and it is possible to improve the scratch resistance while maintaining high adhesiveness.

  In addition to the above, examples of additives such as surfactants include polyalkylene oxides such as polyethylene oxide and polypropylene oxide, higher alcohols, polyhydric alcohols, alkylphenols, and polyalkylenes such as polyethylene oxide and polypropylene oxide in styrenated phenols. Nonionic surfactants such as compounds added with oxides and block copolymers of ethylene oxide and propylene oxide are preferably used. More preferably, an alkylene oxide adduct of phenols is used as the surfactant.

  As the phenol, monocyclic phenol having one aromatic ring and polycyclic phenol having two or more aromatic rings are used. Specific examples of monocyclic phenols include phenol, polycyclic phenols such as phenylphenol, cumylphenol, benzylphenol, hydroquinone monophenyl ether, naphthol, bisphenol, monocyclic phenol or polycyclic phenol, and styrenes (styrene , Α-methylstyrene, etc.) reaction products (referred to as styrenated phenols) of phenols selected from alkylene oxides (for example, ethylene oxide, propylene oxide, butylene oxide) adducts (two or more alkylene oxide adducts) In the case of block or random adduct). Of these, styrenated phenols, ethylene oxide adducts or propylene oxide adducts of bisphenol A are preferably used. The addition method of alkylene oxide to such phenols may be a normal method, and the addition number is preferably 1 to 120, more preferably 10 to 90, particularly preferably 30 to 80. Is done.

  Next, the carbon fiber used in the present invention will be described. Examples of the carbon fiber used in the present invention 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.

  In the carbon fiber according to 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 or more. 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.

  Moreover, in this invention, the strand tensile strength and elastic modulus of said carbon fiber bundle can be calculated | required according to the following procedure based on the resin impregnation strand test method of JIS-R-7608 (2004). As the resin formulation, “Celoxide (registered trademark)” 2021P (manufactured by Daicel Chemical Industries) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / Acetone = 100/3/4 (parts 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.

  The carbon fiber used in the present invention preferably has a surface roughness (Ra) of 6.0 to 100 nm. More preferably, it is 15-80 nm, and 30-60 nm is suitable. Carbon fiber with a surface roughness (Ra) of 6.0 to 60 nm has a highly active edge portion on the surface, so the reactivity with the epoxy group of the sizing agent described above is improved and the interfacial adhesion is improved. This is preferable. Moreover, since the carbon fiber whose surface roughness (Ra) is 6.0-100 nm has an unevenness | corrugation on the surface, it can improve interface adhesiveness by the anchor effect of a sizing agent, and is preferable.

The average roughness (Ra) of the carbon fiber surface can be measured by using an atomic force microscope (AFM). For example, a carbon fiber cut to several millimeters in length is prepared, fixed on a substrate (silicon wafer) using a silver paste, and 3 atomic fibers at the center of each single fiber by an atomic force microscope (AFM). What is necessary is to observe the image of a three-dimensional surface shape. As an atomic force microscope, a Dimension 3000 stage system or the like can be used in NanoScope IIIa manufactured by Digital Instruments and can be observed under the following observation conditions.
・ Scanning mode: Tapping mode ・ Probe: Silicon cantilever ・ Scanning range: 0.6μm × 0.6μm
・ Scanning speed: 0.3Hz
-Number of pixels: 512 × 512
・ Measurement environment: Room temperature, in the atmosphere For each sample, the image obtained by observing one single fiber at a time, approximating the roundness of the fiber cross section with a cubic surface, and the entire image obtained It is preferable to calculate the average roughness (Ra), obtain the average roughness (Ra) for five single fibers, and evaluate the average value.

  In the present invention, the total fineness of the carbon fibers is preferably 400 to 3000 tex. The number of carbon fiber filaments is preferably 1000 to 100,000. In particular, 24,000 or more are preferable. When the number of filaments is large, if the sizing agent-coated carbon fiber bundle loses its flexibility, the spreadability is lowered and the resin impregnation property may be lowered. The sizing agent-coated carbon fiber of the present invention is more preferably applied when the number of filaments is large because flexibility can be maintained. More preferably, it is 36000 or more.

  In the present invention, the single fiber diameter of the carbon fiber is preferably 4.5 to 7.5 μm. Since it is 7.5 micrometers or less, since a carbon fiber with high intensity | strength and elastic modulus can be obtained, it is used preferably. More preferably, it is 6 μm or less, and further preferably 5.5 μm or less. When the thickness is 4.5 μm or more, it is difficult to cause single fiber cutting in the process, and productivity is hardly lowered.

In the present invention, it is the ratio of the number of atoms of oxygen (O) and carbon (C) on the fiber surface measured at a photoelectron escape angle of 45 ° by X-ray photoelectron spectroscopy using AlKα _1,2 as the X-ray source. It is important to use carbon fibers having a surface oxygen concentration (O / C) of 0.10 or more. More preferably, it is 0.18 or more, More preferably, it is 0.2 or more. When the surface oxygen concentration (O / C) is 0.10 or more, the polarity of the carbon fiber is increased, and the carbon fiber surface and the epoxy equivalent are 360 g / eq. The interaction of the following aliphatic epoxy compounds (A) increases. As a result, the epoxy equivalent was 360 g / eq. On the inside of the sizing layer (carbon fiber side). A large amount of the following aliphatic epoxy compound (A) can be present, and a structure in which the sizing layer is unevenly distributed can be formed. Carbon fiber surface and epoxy equivalent of 360 g / eq. By increasing the interaction of the following aliphatic epoxy compound (A), it becomes possible to maintain high adhesiveness. Further, it is preferable that the surface oxygen concentration (O / C) is 0.50 or less because a decrease in strength of the carbon fiber itself due to oxidation can be suppressed. 0.30 or less is more preferable.

The surface oxygen concentration of the carbon fiber is determined by X-ray photoelectron spectroscopy according to the following procedure. First, carbon fibers from which dirt and the like adhering to the carbon fiber surface were removed with a solvent were cut to 20 mm, spread and arranged on a copper sample support base, and then AlKα ₁ and ₂ were used as an X-ray source. The inside of the chamber was measured at 1 × 10 ⁻⁸ Torr. Measurement was performed at a photoelectron escape angle of 45 °. As a correction value for the peak accompanying charging during measurement, the binding energy value of the C _1s main peak (peak top) is adjusted to 284.6 eV. The C _1s peak area is obtained by drawing a straight base line in the range of 282 to 296 eV, and the O _1s peak area is obtained by drawing a straight base line in the range of 528 to 540 eV. The surface oxygen concentration (O / C) is represented by an atomic ratio calculated by dividing the ratio of the O _1s peak area by the sensitivity correction value unique to the apparatus. When ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. is used as the X-ray photoelectron spectroscopy apparatus, the sensitivity correction value unique to the apparatus is 2.33.

  In this invention, it is preferable that the adhesion amount to the carbon fiber of a sizing agent is the range of 0.1-10.0 mass% with respect to sizing agent application | coating carbon fiber. When the sizing agent adhesion amount is 0.1% by mass or more, when the sizing agent-coated carbon fiber is taken out of the bobbin, it can withstand friction caused by a metal guide that passes through, and generation of fuzz can be suppressed. The quality and physical properties of the fiber reinforced composite material are improved. On the other hand, when the adhesion amount of the sizing agent is 10.0% by mass or less, the matrix resin is impregnated inside the carbon fiber without being hindered by the sizing agent film around the sizing agent-coated carbon fiber, and in the obtained 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. More preferably, it is the range of 0.4-3.0 mass%. It is preferable that it is 0.8-2.0 mass%.

  The amount of sizing agent attached was measured by measuring the change in mass before and after the heat treatment when about 2 ± 0.5 g of sizing agent-coated carbon fiber was sampled and heat-treated at 450 ° C. for 15 minutes in a nitrogen atmosphere. The mass change is divided by the mass before heat treatment (mass%).

In the present invention, the thickness of the sizing agent layer applied to the carbon fiber and dried is preferably within a range of 2.0 to 20 nm, and the maximum value of the thickness does not exceed twice the minimum value. By such a uniform sizing agent layer, a large effect of improving adhesiveness can be obtained stably, and further, stable high-order workability can be obtained. The sizing agent-coated carbon fiber of the present invention has 24 filaments. It is preferable that the drape value when the yarn width of the carbon fiber bundle is 75 mm is 3.0 to 10.0 cm.
The drape value is a value representing the hardness of the carbon fiber bundle, and is measured by the following method. Specifically, as shown in FIG. 1 (a), a sizing agent-coated carbon fiber bundle 1 pulled out from a bobbin without applying tension is cut into a length of 40 cm, one end is fixed with a stop tape 2, and the other end is fixed. A 100 g weight 3 is suspended to correct twisting and bending, and then left in an atmosphere at a measurement temperature for 30 minutes. Thereafter, the weight is removed and, as shown in FIG. 1 (b), the sizing agent-coated carbon fiber bundle 5 is placed so as to protrude 25 cm from the horizontal rectangular base 4 having a corner of 90 °, and a 40 cm carbon fiber bundle is placed. After fixing the carbon fiber part on the base with the tape 6 while supporting it so that it does not break, remove the support of the part protruding from the base and let it hang down, and measure the length of the horizontal distance L from the starting point after 2 seconds. Then, the average of the n number of 3 times was defined as the drape value. The larger the drape value, the harder the characteristic.

  When the drape value is 3.0 cm or more, bending or twisting can be suppressed by a guide such as a comb for the purpose of aligning the yarn drawn from the bobbin. If bending or twisting occurs, it is difficult to open the portion, and unevenness in opening is likely to occur, but it is preferable because it can be suppressed. A drape value of 10.0 cm or less indicates that the fiber bundle is not hard, which is preferable because it is easy to open. More preferably, it is 4.0 cm or more and 8.0 cm or less. More preferably, it is 7.0 cm or less.

  Moreover, it is preferable that the draping value of the sizing agent-coated carbon fiber after being stored at room temperature for one year in a state where the sizing agent-coated carbon fiber bundle is wound around a bobbin is 3.0 cm to 12.0 cm.

  The manufacturing method of the sizing agent application | coating carbon fiber in this invention is demonstrated.

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

  In order to further improve the adhesion between the carbon fiber and the matrix resin, a carbon fiber having a surface roughness (Ra) of 6.0 to 100 nm is preferable. In order to obtain a carbon fiber having the surface roughness, a wet spinning method is used. Preferably, the precursor fiber is spun by.

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

  The above spinning solution is spun through a die, discharged in a spinning bath or in the air, and then coagulated in the spinning bath. As the spinning bath, an aqueous solution of a solvent used as a solvent for the spinning dope can be used. It is preferable to use a spinning solution containing the same solvent as the spinning solution, and a dimethyl sulfoxide aqueous solution and a dimethylacetamide aqueous solution are preferable. The fiber solidified in the spinning bath is washed with water and drawn to obtain a precursor fiber. The obtained precursor fiber is subjected to flameproofing treatment and carbonization treatment, and if necessary, further subjected to graphitization treatment to obtain carbon fiber. As conditions for carbonization treatment and graphitization treatment, the maximum heat treatment temperature is preferably 1100 ° C. or higher, more preferably 1400 to 3000 ° C.

  The obtained carbon fiber is usually subjected to an oxidation treatment in order to improve the adhesiveness with the matrix resin, whereby oxygen-containing functional groups are introduced. 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. From the viewpoint of adhesion, a liquid phase electrolytic oxidation is performed in an alkaline electrolytic solution, and then a sizing agent is applied. It is more preferable.

  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.

  The electrolytic treatment may be performed using different electrolytic solutions a plurality of times in different electrolytic solutions. For example, after performing the electrolytic treatment in the acid electrolytic solution, the electrolytic treatment can be performed in the alkaline electrolytic solution, or after the electrolytic treatment in the alkaline electrolytic solution, the electrolytic treatment can be performed in the acidic electrolytic solution.

  The concentration of the electrolytic solution used in the present invention is preferably in the range of 0.01 to 5 mol / L, more preferably in the range of 0.1 to 1 mol / L. When the concentration of the electrolytic solution is 0.01 mol / L 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 / L 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 less than 100 ° C., 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 in} the range. 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, it is preferable to wash and dry the carbon fiber after the electrolytic treatment. As a cleaning method, for example, a dip method or 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. Also, 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, so it is desirable to dry at the lowest possible temperature. Specifically, the drying temperature is preferably 250 ° C. or lower. More preferably, drying is performed at 210 ° C. or lower. On the other hand, considering the efficiency of drying, the drying temperature is preferably 110 ° C. or higher, and more preferably 140 ° C. or higher.

  Next, a method for applying a sizing agent to the carbon fiber produced by the above-described method will be described. In the method for producing a sizing agent-coated carbon fiber of the present invention, at least an epoxy equivalent is 360 g / eq. A sizing agent containing the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule is applied, and further heat-treated at a temperature range of 160 to 260 ° C. for 30 to 600 seconds. .

  In the present invention, as a method for applying the sizing agent to the carbon fiber, an epoxy equivalent of 360 g / eq. The following aliphatic epoxy compound (A), the compound (B) having a terminal unsaturated group and a polar group in one molecule, and a sizing agent-containing solution in which other components are simultaneously dissolved or dispersed are applied at one time. And a method in which each compound (A), (B) and other components are arbitrarily selected and a sizing agent-containing solution that is individually dissolved or dispersed in a solvent and applied to carbon fibers in a plurality of times is preferably used. . In the present invention, it is more preferable to adopt a one-step application in which a sizing agent-containing liquid containing all components of the sizing agent is applied to carbon fibers at a time from the standpoint of effect and ease of processing.

  The sizing agent according to the present invention can be used as a sizing agent-containing liquid obtained by diluting a sizing agent component with a solvent. Examples of such a solvent include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide. Among them, handling is easy and advantageous from the viewpoint of safety. For this reason, an aqueous dispersion or aqueous solution emulsified with a surfactant is preferably used.

  The sizing agent-containing liquid is prepared by emulsifying, with a surfactant, a component containing at least a compound (B) having a terminal unsaturated group and a polar group in one molecule, and an epoxy equivalent of 360 g / eq. It is preferable to prepare by mixing a solution containing at least the following aliphatic epoxy compound (A). At this time, the epoxy equivalent was 360 g / eq. When the following aliphatic epoxy compound (A) is water-soluble, it is previously dissolved in water to form an aqueous solution, and an aqueous emulsion containing at least the compound (B) having a terminal unsaturated group and a polar group in one molecule A method of mixing with a liquid is preferably used from the viewpoint of emulsion stability. The epoxy equivalent was 360 g / eq. It is possible to use the following aliphatic epoxy compound (A), a compound (B) having a terminal unsaturated group and a polar group in one molecule, and an aqueous dispersion in which other components are emulsified with a surfactant as a long-term sizing agent. It can be preferably used from the viewpoint of stability.

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

  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 agent-containing liquid through a roller, a method of contacting the carbon fiber with a roller to which the sizing agent-containing liquid is attached, and a sizing agent. There is a method of spraying the liquid on the carbon fiber in the form of a mist. 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 concentration of the sizing agent-containing liquid, the temperature, the yarn tension, and the like so that the amount of the sizing agent active component 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.

  The liquid temperature of the sizing agent-containing liquid when the sizing liquid is applied to the carbon fiber is preferably in the range of 10 to 50 ° C. in order to suppress fluctuations in the concentration of the sizing agent due to solvent evaporation. In addition, after applying the sizing agent-containing liquid, the amount of sizing agent adhered can be adjusted and uniformly applied to the carbon fiber by adjusting the amount of squeezing out the excess sizing agent-containing liquid.

  After applying the sizing agent to the carbon fiber, it is preferable to heat-treat in the temperature range of 160 to 260 ° C. for 30 to 600 seconds. The heat treatment conditions are preferably in a temperature range of 170 to 250 ° C. for 30 to 500 seconds, and more preferably in a 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, the epoxy equivalent used as the sizing agent is 360 g / eq. The interaction between the following aliphatic epoxy compound (A) and the oxygen-containing functional group on the carbon fiber surface is not promoted, the adhesion between the carbon fiber and the matrix resin is insufficient, or the solvent is sufficiently dried. It may not be removed. On the other hand, when the heat treatment condition exceeds 260 ° C. and / or exceeds 600 seconds, the sizing agent-coated carbon fiber may become hard due to curing.

  The heat treatment can also be performed by microwave irradiation and / or infrared irradiation. When the sizing agent-coated 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 which is the object to be heated can be heated to a desired temperature in a short time. Can be heated. 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.

  The sizing agent-coated carbon fiber of the present invention is suitable for a sheet-like material, woven fabric, knitted fabric, braid, web, mat and chopped, monofilament or bundle-like shape that is substantially two-dimensionally oriented in one direction. Used. In particular, sheet-like materials and woven fabrics arranged in one direction are preferable. Particularly in weaving, carbon fibers are usually prone to fluff due to scrubbing, but the sizing agent-coated carbon fibers of the present invention are suppressed in curing and can suppress fuzz.

  Examples of the sizing agent-coated carbon fibers of the present invention that are aligned in one direction include those in which the sizing agent-coated carbon fibers are aligned in one direction at regular intervals. It is preferable that the sizing agent-coated carbon fibers are repelled in one direction and further fixed in the width direction using heat-fusible fibers as wefts, and then heat-sealed. Further, a heat-fusible web or net may be disposed and fused on one side of a sheet-like material in which sizing agent-coated carbon fibers are repelled.

  The sizing agent-coated carbon fiber of the present invention is preferably used as a woven fabric. The weaving structure is not limited to plain weaving, twill weaving, satin weaving, or any other modification of these original structures. Further, the sizing agent-coated carbon fibers of the present invention may be used for both the warp and warp, but may be mixed with carbon fibers having different sizing agents or fibers other than carbon fibers. The fiber other than carbon fiber may be either an inorganic fiber or an organic fiber. Examples of the inorganic fiber include glass fiber, and examples of the organic fiber include aramid, polyester, polypropylene, polyamide, acrylic, polyimide, and vinylon.

The sizing agent-coated carbon fiber of the present invention is composited with a matrix resin, and is in the form of a unidirectional prepreg, cross prepreg, tow prepreg, short fiber reinforced resin impregnated sheet, short fiber mat reinforced resin impregnated sheet, etc. Used as The matrix resin is not particularly limited, and examples thereof include unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins, melamine resins, urea resins, cyanate ester resins, and bismaleimide resins. Among them, radical polymerization resins such as vinyl ester resins and unsaturated polyester resins are preferably used. For example, unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins, melamine resins, urea resins, cyanate ester resins and Examples thereof include bismaleimide resins. Among these, radical polymerization resins such as unsaturated polyester resins are preferably used.

  Unsaturated polyester resins can be obtained from unsaturated polybasic acids or optionally unsaturated polybasic acids including saturated polybasic acids and polyhydric alcohols. Examples of the unsaturated polybasic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, mesaconic acid, citraconic acid, citraconic anhydride, chloromaleic acid, pyromellitic acid and the like (di) Examples include alkyl esters. These unsaturated polybasic acids can be used individually by 1 type, or can also be used in combination of 2 or more type. Examples of the saturated polybasic acid that replaces part of the unsaturated polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, azelaic acid, adipic acid, sebacic acid, and het acid Etc. These saturated polybasic acids can be used individually by 1 type, or can also be used in combination of 2 or more type.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 1,2-pentane. Propylene oxide addition of diol, 1,6-hexanediol, cyclohexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerin monoallyl ale, bisphenol A, hydrogenated bisphenol A, bisphenol A , Bisphenol A ethylene oxide adduct, glycidylated bisphenol A, glycidylated bisphenol F, glycerin, trimethylolpropane, pentaerythritol, ethylene oxide, pro Ren'okishido, can be mentioned epichlorohydrin. These polyhydric alcohols may be used alone or in combination of two or more.

  Vinyl ester resin, unsaturated polyester resin, and phenol resin have a large interaction with the compound (B) having a terminal unsaturated group and a polar group in one molecule, which is abundant in the outer layer (matrix resin) of the sizing layer, and adhesiveness Is preferable, because the composite physical properties are improved.

  The carbon fiber reinforced composite material of the present invention is suitably used for aircraft members, spacecraft members, automobile members, ship members, civil engineering and building materials, sports equipment, and the like. In particular, it is used for reinforcing sheets such as bridges, piers, and pillars of buildings, small ships, boats, yachts, fishing boats, septic tanks, various tanks, and the like.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not restrict | limited by these Examples.
(1) Strand tensile strength and elastic modulus of carbon fiber bundles Strand tensile strength and strand elastic modulus of carbon fiber bundles 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) / boron trifluoride 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.
(2) Surface oxygen concentration (O / C) of carbon fiber
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 was set in the sample chamber, and the inside of the sample chamber was kept at 1 × 10 ⁻⁸ Torr. Subsequently, AlKα ₁ and ₂ were used as an X-ray source, and the photoelectron escape angle was set to 45 °. In addition, the binding energy value of the C _1s main peak (peak top) was adjusted to 284.6 eV as a correction value for the peak accompanying charging during measurement. The C _1s peak area was determined by drawing a straight base line in the range of 282 to 296 eV. The O _1s peak area was determined by drawing a straight base line in the range of 528 to 540 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.
(3) Measuring method of sizing adhesion amount Weighing about 2 g of sizing adhesion carbon fiber bundle (W1) (reading up to the fourth decimal place), and then setting the temperature at 450 ° C. in a nitrogen stream of 50 ml / min. Leave in an electric furnace (capacity 120 cm ³ ) for 15 minutes to completely pyrolyze the sizing agent. Then, the carbon fiber bundle after being transferred to a container in a dry nitrogen stream at 20 liters / minute and cooled for 15 minutes is weighed (W2) (reading up to the fourth decimal point), and the sizing adhesion amount is measured by W1-W2. Ask. 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.
(4) Measurement of interfacial shear strength (IFSS) The measurement of interfacial shear strength (IFSS) was performed by the following procedures (a) to (d).
(A) Resin adjustment 100 parts of lipoxy R 6540 (manufactured by Showa Denko KK) as the main agent, 0.8 part of 328E (manufactured by Kayaku Akzo Co., Ltd.) as the curing agent, and cobalt N (Showa Denko KK) as the accelerator (Product made) 0.3 part was put into a container, stirred and mixed at room temperature, and then subjected to vacuum evacuation at room temperature for about 10 minutes.
(B) Fixing the carbon fiber single yarn to the dedicated mold The single fiber was extracted from the carbon fiber bundle, and both ends were fixed with an adhesive in a state where a constant tension was 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-dried for 30 minutes or more at the temperature of 80 degreeC. The dumbbell mold was made of silicone rubber, and the shape of the cast part was a central part width of 5 mm, a length of 25 mm, both end part widths of 10 mm, and an overall length of 150 mm.
(C) From resin casting to curing The resin prepared in the above procedure (b) is poured into the mold after vacuum drying in the above step (b), and kept in an oven at 30 ° C. for 24 hours. After heat treatment in an oven for 6 hours, the mold was removed to obtain a test piece. The measurement was carried out after storing the test piece for 24 hours or more at room temperature.
(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 tested with a polarizing microscope. The fiber breakage number N (pieces) in the range of 22 mm at the center of each piece was measured. Next, the average broken fiber length la was calculated by the formula: la (μm) = 22 × 1000 (μm) / N (pieces). Next, the critical fiber length lc was calculated from the average breaking fiber length la by the formula of lc (μm) = (4/3) × la (μm). The strand tensile strength σ and the diameter d of the carbon fiber single yarn were measured, and the interfacial shear strength IFSS, which is an index of the bond strength between the carbon fiber and the resin interface, was 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)
When the value of IFSS is 20 MPa or more, ◯, 10 MPa or more and less than 20 MPa is Δ, and less than 10 MPa is x. ○ is a preferred range in the present invention.
(5) Drape value As shown in FIG. 1 (a), the sizing agent-coated carbon fiber bundle 1 pulled out from the bobbin without applying tension is cut into a length of 40 cm, and one end is fixed with a stop tape 2, A 12 g weight 3 is suspended at one end to correct twisting and bending, and then left in an atmosphere at a measurement temperature for 30 minutes. Next, the weight is removed, and as shown in FIG. 1B, the sizing agent-coated carbon fiber bundle 5 is protruded by 25 cm from the horizontal rectangular base 4 having a corner of 90 °, and the 40 cm carbon fiber bundle is folded. After fixing the carbon fiber part on the table with the stop tape 6 while supporting it so that it does not hang, remove the support of the part protruding from the table and hang it down, measure the length of the horizontal distance L from the starting point after 2 seconds, The average of n times 3 times was defined as the drape value.

  A drape value of 8 cm or less was evaluated as ◯, 10 cm or less as Δ, and a case where it was larger than 10 cm as x. ○ is a preferred range in the present invention.

The materials and components used in each example and each comparative example are as follows.
-(A) component: A-1 to A-3
A-1: “Denacol (registered trademark)” EX-521 (manufactured by Nagase ChemteX Corporation)
Polyglycerin polyglycidyl ether Epoxy equivalent: 183 g / eq. , Epoxy group number: 3 or more,
A-2: “Denacol (registered trademark)” EX-611 (manufactured by Nagase ChemteX Corporation)
Sorbitol polyglycidyl ether Epoxy equivalent: 167 g / eq. Epoxy group number: 4
A-3: Hydrolyzate of A-1.

Polyglycerin polyglycidyl ether Epoxy equivalent: 300 g / eq.
-(A ') component: A-4, A-5
A-4: “Denacol (registered trademark)” EX-841 (manufactured by Nagase ChemteX Corporation)
Polyethylene glycol diglycidyl ether Epoxy equivalent: 372 g / eq. Epoxy group number: 2
A-5: “jER (registered trademark)” 1001 (manufactured by Mitsubishi Chemical Corporation)
Diglycidyl ether of bisphenol A Epoxy equivalent: 475 g / eq. , Epoxy group number: 2,
-(B) component: B-1 to B-2
B-1: UA101H (manufactured by Kyoeisha Chemical)
Glycerin dimethacrylate hexamethylene diisocyanate Number of terminal unsaturated groups: 4 Polar group density: 3.2 × 10 ⁻³
B-2: AII500 (manufactured by Kyoeisha Chemical)
Phenyl glycidyl ether acrylate hexamethylene diisocyanate compound Number of terminal unsaturated groups: 2 Polar group density: 3.4 × 10 ⁻³
-(B ') component: B-3
B-3: A-TMPT (manufactured by Shin-Nakamura Chemical Co., Ltd.)
Trimethylolpropane triacrylate Number of terminal unsaturated groups: 3 Polar group density: None (Reference Example 1)
The carbon fiber used as a raw material was manufactured as follows.

  A copolymer composed of 99 mol% of acrylonitrile and 1 mol% of itaconic acid is dried and wet-spun, fired, total number of filaments 24,000, total fineness 980 tex, specific gravity 1.8, strand tensile strength 6.3 GPa, strand A carbon fiber having a tensile modulus of 330 GPa was obtained. Next, the carbon fiber was subjected to electrolytic surface treatment with an aqueous solution of ammonium hydrogen carbonate having a concentration of 0.1 mol / l as an electrolytic solution at an electric quantity of 80 coulomb per gram of 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. The surface roughness (Ra) of the carbon fiber at this time was 3.0 nm. This was designated as carbon fiber A.

(Reference Example 2)
A sulfuric acid aqueous solution having a concentration of 0.05 mol / l was used as the electrolytic solution, and the same procedure as in Reference Example 1 was carried out except that the amount of electricity was subjected to electrolytic surface treatment at 20 coulomb per g of carbon fiber. At this time, the surface oxygen concentration O / C was 0.13. The surface roughness (Ra) of the carbon fiber at this time was 2.9 nm. This was designated as carbon fiber B.

Example 1
(B) After adjusting the water-dispersed emulsion which consists of 45 parts by weight of (B-1) as component and 5 parts by weight of emulsifier, 50 parts by weight of (A-1) is mixed as component (A) to adjust the sizing liquid. did. As an emulsifier, polyoxyethylene (70 mol) styrenated (5 mol) cumylphenol (weight ratio 90:10) was used.

  After this sizing agent was applied to the carbon fiber A surface-treated by the dipping method, heat treatment was performed at a temperature of 200 ° C. for 90 seconds to obtain a sizing agent-coated carbon fiber bundle. The adhesion amount of the sizing agent was adjusted to 0.6% by mass with respect to the sizing agent-coated carbon fiber. The yarn width of the carbon fiber bundle was 75 mm. Subsequently, the interfacial shear strength (IFSS) and drape value of the sizing agent-coated carbon fiber were measured. The results are summarized in Table 1. As a result, the adhesion measured by IFSS was sufficiently high, and the handling of the carbon fiber indicated by the drape value was also good.

(Example 2)
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that (A-2) was used as the component (A), and physical properties were measured. As shown in Table 1, both adhesion and carbon fiber handling were good.

Example 3
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that (A-3) was used as the component (A), and physical properties were measured. In addition, (A-3) obtained the compound of the predetermined | prescribed epoxy equivalent by heating and stirring the aqueous solution of (A-1). As shown in Table 1, both adhesion and carbon fiber handling were good.

(Comparative Example 1)
The sizing agent-coated carbon fibers were obtained by the method of Example 1 except that the component (A) was not used and (A-4), which is an aliphatic epoxy compound having a large epoxy equivalent, was used, and physical properties were measured. As shown in Table 1, the handleability of the carbon fiber was good, but the adhesion was low.

(Comparative Example 2)
The sizing agent-coated carbon fiber was obtained by the method of Example 1 except that the aromatic epoxy compound (A-5) was used without using the component (A), and the physical properties were measured. As shown in Table 1, the adhesiveness was low, the drape value was high, and the handleability was poor.

Example 4
(B) Sizing agent application | coating carbon fiber was obtained by the method of Example 1 except having used (B-2) as a component, and measured the physical property. As shown in Table 1, both adhesion and carbon fiber handling were good.

(Comparative Example 3)
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that the compound (B) having only a terminal unsaturated group was used without using the compound (B) having a terminal unsaturated group and a polar group in one molecule. The physical properties were measured. As shown in Table 1, the handleability of the carbon fiber was good, but the adhesion was low.

(Comparative Example 4)
(A) Except the point which did not use a component, the sizing agent application | coating carbon fiber was obtained by the method of Example 1, and the physical-property measurement was performed. As shown in Table 2, the handleability of the carbon fiber was good, but the adhesion was low.

(Comparative Example 5)
Sizing agent-coated carbon fibers were obtained by the method of Comparative Example 4 except that the heat treatment temperature was changed from 200 ° C. to 240 ° C., and the physical properties were measured. As shown in Table 2, the adhesion was improved, but the sizing agent-coated carbon fiber was hardened and the drape value was increased.

(Comparative Example 6)
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that only the component (A) was used as the component (A) without using the component (B), and physical properties were measured. As shown in Table 2, the handleability of the carbon fiber was good, but the adhesion was low.

(Comparative Example 7)
Sizing agent-coated carbon fibers were obtained by the method of Comparative Example 6 except that the heat treatment temperature was changed from 200 ° C. to 240 ° C., and the physical properties were measured. As shown in Table 2, the handleability of the carbon fiber was good, but the adhesion was low.

(Examples 5 and 6, Comparative Examples 8 and 9)
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that the ratio of (A) component (A-1) and (B) component (B-1) was changed, and physical properties were measured. The results are shown in Table 3.

(Example 7)
A sizing agent-coated carbon fiber was obtained by the method of Example 1 except that the sizing agent adhesion amount was 1.2% by mass, and physical properties were measured. As shown in Table 4, both adhesiveness and carbon fiber handling were good.

(Example 8)
Sizing agent application | coating carbon fiber was obtained by the method of Example 1 except having used carbon fiber B as carbon fiber, and the physical-property measurement was performed. As shown in Table 4, both adhesiveness and carbon fiber handling were good.

Example 9
(B) As component (B-1), 45 parts by mass, 10 parts by mass of aromatic polyester and 5 parts by mass of an emulsifier were prepared, and then (A) 45 (A-1) was added as component (A). Partially mixed to prepare a sizing solution. The polyester used was the condensate of 2 mol of EO 2 mol adduct of bisphenol A, 1.5 mol of maleic acid and 0.5 mol of sebacic acid, and the emulsifier was the compound of Example 1. Except for the composition of the sizing agent, sizing agent-coated carbon fibers were obtained by the method of Example 1, and the physical properties were measured. As shown in Table 4, both adhesiveness and carbon fiber handling were good.

1: Carbon fiber bundle with sizing agent applied 2: Stopping tape 3: Weight 4: Horizontal rectangular base 5: Carbon fiber bundle with sizing agent applied 6: Stopping tape L: Horizontal distance from start point

  The sizing agent-coated carbon fiber and the method for producing the sizing agent-coated carbon fiber of the present invention have excellent adhesion and handleability, and when used in a carbon fiber reinforced composite material, both processability and high physical properties can be achieved. . In particular, the carbon fiber reinforced composite material has high adhesiveness with unsaturated matrix resins such as vinyl esters, and is excellent in physical properties while being lightweight. Therefore, aircraft members, spacecraft members, automobile members, ship members, civil engineering and building materials and It can be suitably used in many fields such as sports equipment.

Claims (9)

At least the epoxy equivalent is 360 g / eq. A sizing agent containing the following aliphatic epoxy compound (A) and a compound (B) having a terminal unsaturated group and a polar group in one molecule has a mass ratio of (A) / (B) of 30/70 to 70/30. A carbon fiber coated with a sizing agent, characterized in that the carbon fiber is coated at a ratio. The compound (A) is a glycidyl ether type epoxy compound obtained by reaction of one selected from glycerol, diglycerol, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and arabitol with epichlorohydrin. The sizing agent-coated carbon fiber according to claim 1. The sizing agent-coated carbon fiber according to claim 1 or 2, wherein the terminal unsaturated group is selected from a vinyl group, an acrylate group, and a methacrylate group. The sizing agent-coated carbon fiber according to any one of claims 1 to 3, wherein the polar group is selected from an amide bond, an imide bond, a urethane bond, a urea bond, an isocyanate group, and a sulfo group. The sizing agent-coated carbon fiber according to any one of claims 1 to 4, wherein the compound (B) has four terminal unsaturated groups in one molecule. The 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 of the carbon fiber is 0.10 or more. Sizing agent application | coating carbon fiber as described in any one of 1-5. The carbon fiber has at least an epoxy equivalent of 360 g / eq. After applying the following aliphatic epoxy compound (A) and a sizing agent aqueous solution containing a compound (B) having a terminal unsaturated group and a polar group in one molecule, heat treatment is performed at a temperature range of 160 to 260 ° C. for 30 to 600 seconds. The manufacturing method of the sizing agent application | coating carbon fiber as described in any one of Claims 1-6 including the process to do. A sizing agent-coated carbon fiber according to any one of claims 1 to 6, or a sizing agent-coated carbon fiber produced by the method for producing a sizing agent-coated carbon fiber according to claim 7, and a vinyl ester resin or non-carbon fiber. A carbon fiber reinforced composite material composed of a resin mainly composed of a saturated polyester resin. The carbon fiber reinforced composite material according to claim 8, wherein the sizing agent-coated carbon fiber is used in the form of a woven fabric or a sheet-like material aligned in one direction.

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