JP5189547B2 - Carbon fiber bundle and carbon fiber reinforced composite material - Google Patents

Description

  The present invention relates to a sizing agent for carbon fiber, a carbon fiber bundle, and a carbon fiber reinforced composite material.

  One of the fiber reinforced composite materials is a carbon fiber reinforced composite material formed of a reinforcing material made of carbon fiber and a matrix resin. As a method for producing the carbon fiber reinforced composite material, a prepreg impregnated with resin by arranging carbon fibers in one direction or arranging woven carbon fibers on a release paper coated with a thin matrix resin. And a dipping method in which carbon fibers are passed while being immersed in a matrix resin bath. Many of the carbon fiber reinforced composite materials are manufactured by a prepreg method.

As the matrix resin, various resins such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, and a phenol resin are used, and among them, an epoxy resin is widely used.
On the other hand, carbon fibers can be produced using regenerated cellulose, polyacrylonitrile, pitch or the like as starting materials, and fibers in which about 90% or more of the chemical composition is made of carbon are used. Such carbon fibers are classified into, for example, high-strength carbon fibers and high-elasticity carbon fibers. In addition, the carbon fiber is lightweight, excellent in specific strength and specific modulus, and also excellent in heat resistance and chemical resistance, so it is used in a wide range of carbon fiber reinforced composite materials. .

  Carbon fiber reinforced composite materials using carbon fiber as a reinforcing material are lightweight and have excellent strength and elastic modulus. Therefore, they are used for components for sports and leisure products, vehicles and aerospace equipment, energy and civil engineering buildings. Applications are being developed over a wide range of fields as industrial materials. Therefore, there is a strong demand for high performance of carbon fibers as a reinforcing material. In particular, carbon fibers used as structural materials and industrial materials in vehicles and aerospace applications are being developed for the purpose of increasing the strength and increasing the elastic modulus. Carbon fiber reinforced composite materials for use in such structural materials and industrial materials are required to have a high level of tensile strength along the fiber longitudinal direction.

On the other hand, since carbon fiber itself has a low elongation and a brittle nature, fluff is likely to occur due to mechanical friction or the like. Therefore, sizing treatment is performed on the carbon fiber in the manufacturing process of the carbon fiber reinforced composite material for the purpose of suppressing the generation of fuzz. By imparting bundling properties to the carbon fiber by sizing treatment, it becomes possible to suppress the occurrence of fluff of the carbon fiber.
Further, as shown below, a method of performing sizing treatment with a sizing agent imparted with a function of improving the tensile strength in the fiber longitudinal direction of the carbon fiber in addition to the function of improving the converging property of the carbon fiber is shown.
A method of sizing with a sizing agent containing a dimer acid type epoxy resin (Patent Document 1).
A method of sizing with a sizing agent comprising an aliphatic epoxy compound (Patent Document 2).
A method of sizing treatment with a sizing agent containing an epoxy resin having a biphenyl skeleton (Patent Document 3).

JP 2004-149721 A JP-A-7-279040 JP 2007-100250 A

According to the treatment method using the sizing agent in Patent Documents 1 to 3, the tensile strength along the fiber longitudinal direction of the carbon fiber reinforced composite material can be improved.
However, the sizing agent used in these treatment methods may not have sufficient effect of improving the tensile strength depending on the application. Moreover, when the amount of the sizing agent is increased in order to improve the effect, the treated carbon fiber becomes too hard and the handleability is lowered. In particular, carbon fiber reinforced composite materials used for structural materials and industrial materials in vehicles and aerospace applications are required to have excellent tensile strength along the longitudinal direction of the fiber. It is desired to further improve the improvement effect.

  The present invention provides a carbon fiber sizing agent capable of producing a carbon fiber bundle excellent in handleability, which gives a carbon fiber reinforced composite material excellent in tensile strength along the fiber longitudinal direction, and a carbon fiber obtained using the sizing agent An object is to provide a bundle and a carbon fiber reinforced composite material using the carbon fiber bundle.

The present invention employs the following configuration in order to achieve the above-described problems.
[1] A carbon fiber sizing agent containing a dimer acid type epoxy resin (A) and an epoxy resin (B) in which an alkoxysilane compound is introduced into a hydroxyl group of a polymer of an epoxy resin having a hydroxyl group, has an adhesion rate of 0. The carbon fiber bundle formed by adhering to the carbon fiber so that it may become 05-5.0 mass% .
[2] The carbon fiber sizing agent further contains an emulsifier, the content of the epoxy resin (A) in the carbon fiber sizing agent is 20 to 70% by mass, and the content of the epoxy resin (B) the amount is 20 to 70 wt%, the content of the emulsifier is 10 to 30 wt%, the carbon fiber bundle according to [1].
[ 3 ] A carbon fiber reinforced composite material using the carbon fiber bundle according to [ 1 ] or [2] .

By using the sizing agent for carbon fiber of the present invention, a carbon fiber bundle excellent in handleability which gives a carbon fiber reinforced composite material excellent in tensile strength along the fiber longitudinal direction can be obtained.
Moreover, the carbon fiber bundle of the present invention is excellent in handleability, and a carbon fiber reinforced composite material having excellent tensile strength along the fiber longitudinal direction can be obtained by using the carbon fiber bundle.
Moreover, the carbon fiber reinforced composite material of the present invention is excellent in tensile strength along the fiber longitudinal direction.

[Carbon fiber sizing agent]
The sizing agent for carbon fiber of the present invention (hereinafter referred to as “the sizing agent”) is a dimer acid type epoxy resin (A) (hereinafter referred to as “epoxy resin (A)”) and an epoxy resin having a hydroxyl group. And an epoxy resin (B) in which an alkoxysilane compound is introduced into the hydroxyl group of the polymer (hereinafter referred to as “epoxy resin (B)”).

The epoxy resin (A) is a dimer acid type epoxy resin. That is, it is an epoxy resin in which a glycidyl group is introduced into a dibasic acid obtained by dimerizing an unsaturated fatty acid.
From the viewpoint of flexibility, the unsaturated fatty acid is preferably a higher unsaturated fatty acid having 11 to 22 carbon atoms.
Examples of higher unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, eicosenoic acid, docosenoic acid, branched octadecenoic acid, branched hexadecenoic acid, and undecylenic acid.
An epoxy resin (A) may be used individually by 1 type, and may use 2 or more types together.

  As a commercial item of an epoxy resin (A), brand name "JER871" and "JER872" (above, the Japan Epoxy Resin company make) which are the epoxy resins which introduce | transduced the glycidyl group into the dimer of a linolenic acid are mentioned, for example.

  The content of the epoxy resin (A) in the present sizing agent (100% by mass) is preferably 20 to 70% by mass, and more preferably 30 to 50% by mass. If content of an epoxy resin (A) is 20 mass% or more, the softness | flexibility of the carbon fiber bundle obtained will improve. Moreover, if content of an epoxy resin (A) is 70 mass% or less, an epoxy resin (B) will decrease too much and the tensile strength along the fiber longitudinal direction of the carbon fiber reinforced composite material finally obtained will be. It is easy to suppress the decrease.

The epoxy resin (B) is an epoxy resin in which an alkoxysilane compound is introduced into a hydroxyl group of a polymer of an epoxy resin having a hydroxyl group.
Examples of the epoxy resin having a hydroxyl group include an epoxy resin polymer. Specific examples include a polymer of bisphenol A type epoxy resin, a polymer of bisphenol F type epoxy resin, a polymer of phenol novolac epoxy resin, and the like.
Examples of the alkoxysilane compound include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, and phenyl. Examples include trimethoxysilane and phenyltriethoxysilane.
An epoxy resin (B) may be used individually by 1 type, and may use 2 or more types together.

  As a commercially available product of the epoxy resin (B), for example, trade names “Composeran E201” and “Composeran E202” (Arakawa Chemical Co., Ltd.), which are epoxy resins obtained by introducing an alkoxysilane compound into a polymer of a bisphenol A type epoxy resin. Manufactured).

  The content of the epoxy resin (B) in the sizing agent (100% by mass) is preferably 20 to 70% by mass, and more preferably 30 to 50% by mass. If content of an epoxy resin (B) is 20 mass% or more, a carbon fiber bundle with high tensile strength along a fiber longitudinal direction will be easy to be obtained. Moreover, if content of an epoxy resin (B) is 70 mass% or less, it will be easy to suppress that the interface resin layer formed with an epoxy resin (B) on a carbon fiber bundle becomes too hard.

Moreover, this epoxy resin (C) other than an epoxy resin (A) and an epoxy resin (B) may contain in this sizing agent. The other epoxy resin (C) may be either liquid or solid epoxy resin.
Examples of other epoxy resins (C) include bisphenol A type epoxy resins obtained from bisphenol A, bisphenol F type epoxy resins obtained from bisphenol F, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, alkanediol diglycidyl. Examples thereof include diglycidyl ethers such as ether. Especially, it is more preferable to use a bisphenol A type epoxy resin from the point of viscosity adjustment.
These other epoxy resins (C) may be used alone or in combination of two or more.

  When this sizing agent is attached to the carbon fiber, the above-mentioned epoxy resin (A), epoxy resin (B), and other epoxy resin (C) used as necessary are mixed with water, acetone, ethanol, dimethyl. It is preferable to use as a sizing solution by dispersing and dissolving in an organic solvent such as formamide. However, it is preferable that the sizing liquid is dispersed and dissolved in water from the viewpoint of little influence on the human body, environment, and process. Hereinafter, the present sizing agent in which each of the above components is dispersed in a dispersion medium such as water is particularly referred to as a sizing dispersion.

Moreover, when using the sizing dispersion liquid which disperse | distributed each said component in water as this sizing agent, it is preferable to use an emulsifier as a dispersion medium. The emulsifier is not particularly limited, and a nonionic emulsifier is preferable from the viewpoint of storage stability of the sizing dispersion.
Examples of the nonionic emulsifier include higher alcohol ether type polyoxyethylene adducts, higher fatty acid type polyoxyethylene adducts, and alkylphenyl ether type polyoxyethylene adducts. Especially, since the emulsification performance with respect to an epoxy resin (A) and an epoxy resin (B) is especially high, the alkyl phenyl ether type polyoxyethylene adduct is more preferable.

  The emulsifier content in the sizing dispersion is preferably 10 to 30% by mass. If content of an emulsifier is 10 mass% or more, it will be easy to disperse | distribute resin components, such as an epoxy resin (A) and an epoxy resin (B), stably in a sizing dispersion liquid. Moreover, if content of an emulsifier is 30 mass% or less, the effect by an epoxy resin (A) and an epoxy resin (B) will be easy to be acquired.

  The sizing dispersion preferably has a solid content concentration of more than 0.1% by mass and less than 12% by mass. When the solid content concentration is more than 0.1% by mass, the handleability of the obtained carbon fiber bundle is improved. Moreover, if solid content concentration is less than 12 mass%, it will become easy to make a sizing dispersion liquid adhere to carbon fiber.

  As a result of intensive studies, the inventors of the present invention have adhered the sizing agent containing the above-described epoxy resin (A) and epoxy resin (B) as essential components to the carbon fiber, thereby obtaining a fiber longitudinal direction of the obtained carbon fiber bundle. It was found that a carbon fiber reinforced composite material excellent in tensile strength in the fiber longitudinal direction can be obtained by using the carbon fiber bundle after the sizing treatment.

Although the details of the technical action by which the effect of improving the tensile strength in the fiber longitudinal direction can be obtained by the present sizing agent are not clear, the following factors can be considered.
The alkoxysilane part which an epoxy resin (B) has can react between molecules, and can form a coating film by it. Moreover, since the alkoxysilane part can be chemically bonded to the functional group present on the surface of the carbon fiber by the coupling function, the epoxy resin (B) remains in the vicinity of the interface with the carbon fiber. Furthermore, the epoxy resin (B) can react with the epoxy resin (A) having a flexible structure simultaneously with the coating film forming reaction and the coupling reaction. Thereby, since an epoxy resin (A) also remains in the interface vicinity, it becomes possible to form the interface resin layer which has a flexible physical property in the interface vicinity with carbon fiber. The presence of this flexible interfacial resin layer suppresses the progress of cracks that occur when a tensile load is applied, and thus it is considered that the treated carbon fiber bundle can exhibit excellent tensile strength.
Moreover, the epoxy resin (A) and the epoxy resin (B) have very low solubility in the epoxy resin constituting the matrix resin impregnated in the carbon fiber in the carbon fiber reinforced composite material. Therefore, it is difficult to mix with the matrix resin, and it is considered that the interface resin layer is easily maintained by staying in the vicinity of the interface of the carbon fiber bundle even when the carbon fiber reinforced composite material is manufactured.

Further, in the present sizing agent, as long as the tensile strength along the fiber longitudinal direction of the carbon fiber reinforced composite material produced by the carbon fiber bundle obtained using the present sizing agent is within a range that does not excessively decrease, An additive may be contained in addition to the components.
Examples of the additive include other resins such as a dispersant, a curing agent, polyethylene glycol, polyurethane, and polyester.

[Carbon fiber bundle]
The carbon fiber bundle of the present invention (hereinafter referred to as “the present carbon fiber bundle”) is a carbon fiber bundle formed by adhering the above-described sizing agent.
As the carbon fiber to which the present sizing agent is attached, various carbon fibers such as polyacrylonitrile (PAN), pitch, and rayon / cellulose can be used. Of these, PAN-based carbon fibers are preferable because desired carbon fibers with high elasticity and high strength can be easily obtained.
As the carbon fiber, for example, a medium elastic type carbon fiber having a tensile elastic modulus of 250 GPa or more and a high elastic type carbon fiber having a tensile elastic modulus of 300 GPa or more can be used, and a carbon fiber having a tensile elastic modulus of 250 GPa to 300 GPa is preferable. Here, the tensile elastic modulus means a value measured according to JIS R7608.
Moreover, conditions, such as the fiber diameter of a carbon fiber and the number of filaments of a carbon fiber bundle, are not specifically limited, What is necessary is just to select suitably according to a use.

The adhesion rate of the present sizing agent in the present carbon fiber bundle is 0.05 to 5.0% by mass, and preferably 0.20 to 1.0% by mass.
If the adhesion rate of the present sizing agent is 0.05% by mass or more, it becomes easy to cover the entire carbon fiber surface with the present sizing agent. Moreover, when manufacturing this carbon fiber reinforced composite material, when this carbon fiber bundle and a matrix resin are mixed, it can suppress that functional expression, such as toughness by the interface resin layer mentioned above falls. Further, if the adhesion rate of the present sizing agent is 5.0% by mass or less, the carbon fiber bundle is hardened by depositing too much of the present sizing agent on the carbon fiber surface, so that the handleability of the present carbon fiber bundle is improved. It can suppress that it falls. In addition, in the carbon fiber reinforced composite material, it is possible to suppress a failure in transmission of stress transmitted from the matrix resin to the carbon fiber via the interface resin layer, and deterioration of mechanical characteristics.

The adhesion rate of the sizing agent can be obtained by the following formula (1).
R = 100 × (W2−W1) / W1 (1)
R: Adhesion rate (unit: mass%)
W1: Mass of carbon fiber before adhering this sizing agent (unit: g)
W2: Mass of carbon fiber after adhering this sizing agent (unit: g)

The present carbon fiber bundle is suitable as a carbon fiber material in a carbon fiber reinforced composite material containing carbon fibers and a matrix resin.
This carbon fiber bundle is excellent in tensile strength along the longitudinal direction of the fiber because the sizing agent is attached to the carbon fiber bundle. Therefore, by using this carbon fiber bundle, the tensile strength along the longitudinal direction of the fiber is excellent. A carbon fiber reinforced composite material can be obtained.

[Method for producing carbon fiber bundle]
The manufacturing method of the carbon fiber bundle of this invention is a method which has the process of apply | coating this sizing agent to the carbon fiber mentioned above. In the production method, the sizing agent is preferably used as a sizing liquid (sizing dispersion).
As a method for applying the sizing liquid to the carbon fiber, any method can be used as long as the sizing liquid can be uniformly applied to the carbon fiber. For example, a roller sizing method, a spray method, and a method of immersing the carbon fiber bundle in the sizing liquid. The roller dipping method to apply | coat is mentioned. Among these, the roller dipping method is preferable because it is easy to uniformly apply the sizing liquid even to a carbon fiber bundle having a large number of single fibers per bundle.

  The adhesion rate R of the sizing agent in the carbon fiber bundle can be adjusted by adjusting the solid content concentration of the sizing agent. For example, the application amount of the sizing agent can be adjusted by adjusting the solid content concentration to about twice (about 2.5 R) according to the adhesion rate R.

After applying this sizing solution, the solvent (dispersion medium) is removed in the drying step.
The drying is preferably performed at a temperature of 120 to 250 ° C. for 10 seconds to 15 minutes, and more preferably at a temperature of 140 to 200 ° C. for 30 seconds to 10 minutes. When the drying temperature is 120 ° C. or higher, the solvent is easily removed. Moreover, if the drying temperature is 250 ° C. or less, it is easy to prevent the quality of the present carbon fiber bundle from being deteriorated by heat.

[Carbon fiber reinforced composite material]
The carbon fiber reinforced composite material of the present invention (hereinafter referred to as “the present composite material”) is a composite material using the present carbon fiber bundle, and is formed of a reinforcing material composed of the present carbon fiber bundle and a matrix resin. .
As the matrix resin, a matrix resin usually used for a carbon fiber reinforced composite material can be used, and examples thereof include various resins such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, and a phenol resin.
As a manufacturing method of this composite material, the manufacturing method normally used for manufacture of a carbon fiber reinforced composite material can be used except using this carbon fiber bundle.

  The composite material preferably has a 0 ° tensile strength of 2800 to 3300 MPa. Here, 0 degree tensile strength means the value measured by the method which made the crosshead speed of the tensile tester 1.27 mm / min and n = 6 based on ASTM-D3039.

Since the present composite material described above uses the present carbon fiber bundle that has been subjected to sizing treatment using the present sizing agent, the tensile strength along the fiber longitudinal direction is excellent.
The use of the composite material is not particularly limited, but is particularly suitable as a structural material or industrial material for vehicle / aerospace applications.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
<Preparation of sizing agent>
Each component used for the preparation of the sizing agent in this example is shown below.
[Epoxy resin (A)]
A-1: JER872 (trade name, epoxy resin having a glycidyl group introduced into a dimer of linolenic acid, manufactured by Japan Epoxy Resin Co., Ltd.)

[Epoxy resin (B)]
B-1: Composelane E-201 (trade name, epoxy resin in which an alkoxysilane compound is introduced into the hydroxyl group of a polymer of bisphenol A type epoxy resin, manufactured by Arakawa Chemical Co., Ltd.)

[Other resins (C)]
C-1: JER1001 (trade name, bisphenol A type epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.)
C-2: JER828 (trade name, bisphenol A type epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.)
C-3: Epiol E-1000 (trade name, aliphatic epoxy resin having a polyoxyethylene skeleton, manufactured by NOF Corporation)
C-4: YX-4000 (trade name, epoxy resin having a biphenyl skeleton, manufactured by Japan Epoxy Resin Co., Ltd.)

[Emulsifier (D)]
D-1: Emanon CH-25 (trade name, nonionic emulsifier, manufactured by Kao Corporation)

[Production Example 1]
45 mass% of resin (A-1) which is epoxy resin (A) and 45 mass% of resin (B-1) which is epoxy resin (B) are mixed with 10 mass% of emulsifier (D-1). By dispersing, a sizing dispersion having a solid content concentration of 1.0% by mass was obtained.

[Production Examples 2 to 12]
A sizing dispersion was obtained in the same manner as in Production Example 1 except that the composition of the resin mixed and dispersed in the emulsifier (D-1) was changed as shown in Table 1. The solid content concentrations of the obtained sizing dispersions are as shown in Table 1.

<Manufacture of carbon fiber reinforced composite materials>
Next, the carbon fiber bundle is sizing using the sizing dispersion obtained in Production Examples 1 to 12, and along the fiber longitudinal direction of the carbon fiber reinforced composite material (cured plate) created using the carbon fiber bundle. The tensile strength was evaluated.
[Example 1]
(Sizing process)
The trade name “Pyrofil MR60H” (carbon fiber bundle, 24,000 filaments, fiber diameter 5 μm, manufactured by Mitsubishi Rayon Co., Ltd.) was used as the carbon fiber for sizing treatment.
After filling the sizing dispersion obtained in Production Example 1 in a dipping tank having a free roller and immersing the carbon fiber bundle in the sizing dispersion, a drying treatment is performed for 10 minutes in an atmosphere at a temperature of 140 ° C. The carbon fiber bundle that had been applied and sized was wound around a bobbin. The adhesion rate R of the sizing agent in the obtained carbon fiber bundle was 0.35% by mass.
(Preparation of matrix resin)
50 parts by mass of trade name “JER828” (bisphenol A type epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.), 50 parts by mass of product name “JER604” (tetraglycidyl type epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.), and trade name A matrix resin was prepared by mixing 10 parts by mass of “Phenototo YP-70” (phenoxy resin, manufactured by Toto Kasei Co., Ltd.) and 32 parts by mass of 4,4′-diaminodiphenylsulfone (manufactured by Wakayama Seika Co., Ltd.). did.
(Create prepreg)
A hot melt sheet was prepared by thinly applying the matrix resin on a release paper. Thereafter, the sizing-treated carbon fiber bundles were arranged in parallel on the hot melt sheet and impregnated with a matrix resin. The obtained prepreg had a matrix resin content of about 35% by mass and a fiber basis weight of 200 g / m ² .
(Creating a hardened plate)
The prepreg is laminated with the orientation of the carbon fiber bundle aligned in one direction, and is heated and pressurized using an autoclave (temperature is raised from room temperature to 180 ° C. over 2 hours, at a temperature of 180 ° C. and a pressure of 0.6 MPa. Held for 2 hours) to produce a cured plate having a thickness of 1 mm.

[Examples 2 to 7]
A cured plate was produced in the same manner as in Example 1 except that the sizing dispersion used in the sizing treatment and the adhesion rate R of the sizing agent were changed as shown in Table 2. The adhesion rate R was adjusted by adjusting the solid content concentration of the sizing dispersion.

[Comparative Examples 1-5]
A cured plate was produced in the same manner as in Example 1 except that the sizing dispersion used in the sizing treatment and the adhesion rate R of the sizing agent were changed as shown in Table 2. The adhesion rate R was adjusted by adjusting the solid content concentration of the sizing dispersion.

[Measurement of tensile strength along the longitudinal direction of fiber]
About the hardening board obtained by the Example and the comparative example, the tensile strength along the fiber longitudinal direction was evaluated by measuring 0 degree tensile strength with the method shown below.
(Measurement of 0 ° tensile strength)
The 0 ° tensile strength was measured according to ASTM-D3039 by cutting out a test piece having a length of 230 mm and a width of 12.5 mm from the cured plates obtained in Examples and Comparative Examples. The measurement conditions were a tensile tester (manufactured by Instron, trade name: universal tester 5882 type) with a crosshead speed of 1.27 mm / min and n = 6.
Table 2 shows the measurement results of the adhesion rate R of the sizing agent and the 0 ° tensile strength of each cured plate in the examples and comparative examples.

As shown in Table 2, the cured plates of Examples 1 to 7 prepared using a carbon fiber bundle in which the present sizing agent was adhered so that the adhesion rate R was 0.05 to 5.0% by mass, The 0 ° tensile strength was high, and the tensile strength along the fiber longitudinal direction was excellent.
In addition, from comparison between Examples 1 to 5 and Examples 6 and 7, by using a sizing agent in which the contents of the epoxy resin (A) and the epoxy resin (B) are both 20% by mass or more, the longitudinal direction of the fiber It was found that a carbon fiber reinforced composite material having a higher tensile strength along the line was obtained.

On the other hand, in Comparative Example 1 in which the adhesion rate R of the sizing agent was 5.1% by mass, the carbon fiber bundle was very hard and cured because the process passability in the subsequent prepreg creation process and the cured plate creation process was poor. The plate could not be obtained and the tensile strength could not be measured.
Moreover, in Comparative Examples 2 and 3 sized with a sizing agent containing only one of the epoxy resin (A) and the epoxy resin (B), the obtained cured plate has a low 0 ° tensile strength, which is lower than that of the example. The tensile strength along the fiber longitudinal direction was poor.
Moreover, also in Comparative Examples 4 and 5 in which sizing treatment was performed with a sizing agent containing neither epoxy resin (A) nor epoxy resin (B), the obtained cured plate had a low 0 ° tensile strength, and the fiber length was longer than that of the examples. The tensile strength along the direction was poor.

Claims (3)

Dimer acid type epoxy resin (A),
Carbon fiber sizing agent containing epoxy resin (B) in which an alkoxysilane compound is introduced into the hydroxyl group of an epoxy resin polymer having a hydroxyl group, and carbon fiber so that the adhesion rate is 0.05 to 5.0% by mass. A carbon fiber bundle made by adhering . The carbon fiber sizing agent further comprises an emulsifier,
Wherein 20 to 70% by weight content of carbon fibers for the epoxy resin in the sizing agent (A), the content of the previous SL epoxy resin (B) is 20 to 70 wt%, the content of the emulsifying agent The carbon fiber bundle according to claim 1, wherein is 10 to 30% by mass. A carbon fiber reinforced composite material using the carbon fiber bundle according to claim 1 .