JP2016160549A - Sizing agent for carbon fiber, carbon fiber bundle, sheet-like substrate and carbon fiber reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sizing agent for carbon fiber capable of providing a carbon fiber bundle having high smoothness, excellent processing passing property in a high level processing process of the carbon fiber bundle and further excellent in mechanical physical enhancing effect.SOLUTION: A sizing agent for carbon fiber satisfies following (1) to (4). (1) It contains a compound (A) which is an ester compound of an epoxy compound having a plurality of epoxy groups in a molecule and unsaturated mono basic acid and has at least one epoxy group in a molecule, a bifunctional type urethane acrylate oligomer compound (B) having tensile elongation rate of a cured article of 40% or more, a stearic acid ester compound (C) and a surfactant (D). (2) A ratio of the urethane acrylate oligomer (B)/the compound (A) is 1/3 to 2/1. (3) Total percentage of the compound (A) and the urethane acrylate oligomer (B) in the all sizing component is 20 mass% or more. (4) Percentage of the stearic acid ester compound (C) in the all sizing agent component is 5 to 30 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a carbon fiber sizing agent, a carbon fiber bundle to which a sizing agent is attached, a sheet-like base material, and a carbon fiber reinforced composite material.

  Generally, the carbon fiber is a filament having a diameter of about 5 to 8 μm, and the single fiber is used in a form (hereinafter, referred to as “carbon fiber bundle”) in a unit of several thousand to several tens of thousands. Since the carbon fiber itself has a low elongation and a brittle nature, fluff is likely to occur due to mechanical friction or the like, and fluff and thread breakage are likely to occur in the manufacturing process of the composite material. Therefore, it is common to provide a sizing agent to the carbon fiber for the purpose of imparting convergence and suppressing fluff.

  Carbon fiber is formed by compounding with a resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin, acrylic resin (hereinafter referred to as matrix resin) to form a so-called carbon fiber reinforced composition, and then molding. Although used as a carbon fiber reinforced composite material in a wide range of fields, it is necessary to easily and completely impregnate the carbon fiber bundle with the matrix resin in the step of impregnating the matrix resin. .

  However, carbon fiber is poor in wettability with respect to the matrix resin as it is, and is difficult to be impregnated with the matrix resin. Therefore, the quality of the obtained fiber reinforced composite material cannot be sufficiently satisfied. For the purpose of improving this, sizing treatment for carbon fibers is effective.

  That is, the carbon fiber is treated with a sizing agent for the purpose of improving the handleability of the carbon fiber and improving the wettability with respect to the matrix resin and industrially producing a high-quality carbon fiber reinforced composite material. It is given.

  As a method for producing a carbon fiber reinforced composition, a method in which a fiber as a reinforcing material is impregnated with a matrix resin is generally used. As a method of impregnating fibers with a matrix resin, a resin is applied and impregnated on a base material (hereinafter referred to as “sheet-like base material”) in which a plurality of carbon fiber bundles are aligned in one direction to form a sheet. After a method, a carbon fiber bundle is processed by a loom to form a sheet-like substrate such as a fabric, a resin is applied to the fabric sheet-like substrate and impregnated, or a plurality of fiber bundles are aligned in one direction, A method of applying and impregnating a resin to a so-called multiaxial laminated knitted sheet-like substrate obtained by laminating and stitching a plurality of unidirectional fiber sheet-like substrates after forming a unidirectional fiber sheet-like substrate There are various ways.

  On the other hand, a so-called large tow carbon fiber bundle (hereinafter referred to as “large tow”) having more than 24,000 single fibers has been put on the market. Since large tow has high productivity, its use is expanding for the purpose of reducing the cost of carbon fiber reinforced composite materials. However, compared with a carbon fiber bundle called small tow (hereinafter referred to as “small tow”) having a smaller number of filaments than 24,000, the fiber when the fiber bundle is widened by high-order processing and used. There is a surface inferior to the uniform spreadability (opening property) of the bundle. Therefore, when used for thin prepregs and thin fabrics with a small amount of fibers, a gap (hereinafter sometimes referred to as “open space”) is produced between the fiber bundles, and the carbon fiber reinforced composite finally obtained The performance and quality of the material may be deteriorated.

  Therefore, in the process of opening the large tow by mechanical friction or rubbing using a metal bar or the like, it is necessary to increase the number of rubbing or to give high tension to the fiber bundle. By rubbing, fluff is likely to occur in the fiber bundle, or single fiber breakage tends to occur.

  The properties of the sizing agent imparted to the carbon fiber also greatly affect the spreadability. When the sizing agent has high adhesiveness, carbon fiber is used on the surface of a metal guide bar installed in the fiber-spreading process or on the surface of a stitch needle used for stitching when manufacturing a multiaxial laminated knitted sheet-like substrate. The sizing agent applied to the material may be transferred and deposited, and this deposit may further generate fluff in the fiber bundle.

  For this reason, the sizing agent imparted to carbon fiber bundles that require high fiber opening properties, particularly large tow carbon fiber bundles, has a problem of achieving both smoothness (= abrasion resistance and fuzz resistance) and convergence. there were.

  In order to solve the above-mentioned problem, for example, Patent Document 1 discloses that bisphenol A type epoxy resin that is liquid at room temperature, bisphenol A type epoxy resin that is solid at room temperature, An unsaturated polyester resin, which is a condensate of a dibasic acid and an alkylene oxide adduct of bisphenol A, and a sizing agent having a stearic acid ester as essential components have been proposed.

  However, even if the sizing agent described in Patent Document 1 is applied to a large tow, the scratch resistance can be improved, but due to the size of the tow volume, there is a case where it is difficult to achieve convergence. . In addition, when the matrix resin is a radical polymerization system, the obtained carbon fiber composite material may not always have sufficient mechanical properties.

  Patent Document 2 proposes a sizing agent comprising an ester resin containing one or more epoxy groups, a urethane acrylate, an anionic emulsifier, and a small amount of a nonionic emulsifier.

  The sizing agent described in Patent Document 2 has excellent adhesion to radical polymerization resins such as unsaturated polyester resins, vinyl ester resins, and acrylic resins, and can provide the same performance as a composite material using an epoxy resin as a matrix resin. Is. In addition, compatibility with epoxy resin may be good, and it is possible to express excellent mechanical strength with a composite material combined with a wide range of thermosetting resin, but when applied to large tow In some cases, it is difficult to achieve both the scratch resistance and the convergence as described above.

Japanese Patent Application Laid-Open No. 07-197381 JP 2008-95241 A

  The present invention has been made in view of the above circumstances, has high smoothness, exhibits excellent process passability in a high-order processing step of a carbon fiber bundle, and particularly when applied to large tow. An object of the present invention is to provide a sizing agent for carbon fiber that can obtain a carbon fiber bundle that exhibits a sufficient effect and that is excellent in mechanical properties when combined with a matrix resin, particularly a radical polymerization resin. To do. Another object of the present invention is to provide a carbon fiber bundle excellent in the mechanical property improving effect of the composite material, a sheet-like substrate having the carbon fiber bundle, and a carbon fiber reinforced composite material excellent in mechanical property.

The present invention relates to a carbon fiber sizing agent that satisfies the following (1) to (4).
(1) The carbon fiber sizing agent contains the following (A) to (D).
-An ester compound of an epoxy compound having a plurality of epoxy groups in the molecule and an unsaturated monobasic acid, and a compound having at least one epoxy group in the molecule (A)
-Bifunctional urethane acrylate oligomer compound (B) with a tensile elongation of the cured product of 40% or more
・ Stearic acid ester compound (C)
・ Surfactant (D)
(2) The mass ratio of the content of the compound (A) and the urethane acrylate oligomer (B) is 1/3 or more and 2/1 or less as the ratio of urethane acrylate oligomer (B) / compound (A).
(3) The ratio of the total amount of the compound (A) and the urethane acrylate oligomer (B) in all sizing components is 20% by mass or more.
(4) The proportion of the stearic acid ester compound (C) in all sizing components is 5% by mass or more and 30% by mass or less.

Furthermore, the sizing agent of the present invention may satisfy the following (5) and (6).
(5) An ester of an alkylene oxide adduct of bisphenols and a dicarboxylic acid compound, the ester compound (E) having an acid value of 50 or more.
(6) Content of the said ester compound (E) is 2.0 mass times or less of the total amount of the said compound (A) and the said urethane acrylate oligomer (B).

  Moreover, this invention relates to the carbon fiber bundle which the said sizing agent for carbon fibers adhered with the adhesion amount 0.6 mass% or more and 2.0 mass% or less.

  The present invention also relates to a sheet-like base material including the carbon fiber bundle, a carbon fiber reinforced composite material including the carbon fiber bundle, and a carbon fiber reinforced composite material including the sheet-like base material.

  According to the present invention, it has high smoothness, exhibits excellent process passability in a high-order processing step of a carbon fiber bundle, and this effect is sufficiently exerted even when applied to large tow, and the matrix resin. In particular, an object of the present invention is to provide a carbon fiber sizing agent and an aqueous dispersion of a sizing agent capable of obtaining a carbon fiber bundle excellent in mechanical property improvement effect when combined with a radical polymerization resin. Also provided are a carbon fiber bundle excellent in the mechanical property improving effect of the composite material, a sheet-like material having the carbon fiber bundle, and a carbon fiber reinforced composite material excellent in mechanical property.

<Carbon fiber sizing agent>
The sizing agent for carbon fiber of the present invention includes (A) to (D) described in detail below. This sizing agent can be obtained by appropriately mixing each component.

<Compound (A)>
The compound (A) contained in the carbon fiber sizing agent of the present invention is a compound having at least one epoxy group in the molecule. The compound (A) refers to an ester compound obtained by reacting an epoxy compound having a plurality of epoxy groups in the molecule with an unsaturated monobasic acid. In the present invention, an epoxy group means a group whose ring skeleton has a three-membered ring composed of two carbon atoms and one carbon atom in its structure. Specific examples include a functional group represented by the following general formula (e1), a functional group (glycidyl group) represented by the following general formula (e2), and other cyclic aliphatic epoxy groups. Examples of other cycloaliphatic epoxy groups include groups having a cyclic structure formed by the three-membered ring and a monocyclic or polycyclic aliphatic ring in the structure. For example, the following general formula ( The functional group represented by e3)-(e5) can be illustrated.

<Epoxy compound having a plurality of epoxy groups in the molecule>
In the compound (A), the epoxy compound having a plurality of epoxy groups in the molecule is not particularly limited, and examples thereof include bisphenol epoxy compounds, bisphenol alkylene oxide addition epoxy compounds, and hydrogenated bisphenols. Examples thereof include epoxy compounds and alkylene oxide-added epoxy compounds of hydrogenated bisphenols. These bisphenols are not particularly limited, and examples thereof include bisphenol F type, bisphenol A type, and bisphenol S type. Epoxy resins such as phenol novolak type, cresol novolak type, diphenyl type, dicyclopentadiene type, naphthalene skeleton type other than epoxy compounds of bisphenols can also be used. Further, it may have a linear aliphatic skeleton.

<Unsaturated monobasic acid>
In the compound (A), the unsaturated monobasic acid is not particularly limited as long as it is a compound having one unsaturated group and one carboxyl group. The unsaturated group is not particularly limited, but is preferably a vinyl group or a propenyl group, more preferably a vinyl group, because it is not bulky and does not lower the rigidity of the main chain of the ester formed. Particularly preferred is acrylic acid or methacrylic acid. That is, the compound (A) is preferably an ester of the epoxy compound and acrylic acid or methacrylic acid.

The compound (A) is an ester compound obtained by reacting a compound having a plurality of epoxy groups with an unsaturated monobasic acid. In this reaction, among the epoxy groups of a compound having a plurality of epoxy groups, At least one epoxy group remains unreacted and at least one epoxy group is opened by an unsaturated monobasic acid to form a so-called half ester having an unsaturated group. Such a compound (A) includes an epoxy group derived from a compound having a plurality of epoxy groups in the molecule and an unsaturated group derived from an unsaturated monobasic acid (for example, CH ₂ ═CH—COO— derived from acrylic acid). Thus, the coupling function between the carbon fiber surface and the resin molecule is exhibited, and the interfacial adhesion between the carbon fiber and the resin is greatly improved. In particular, radical polymerization resins such as unsaturated polyester resins, vinyl ester resins, and acrylic resins can be strongly bonded to carbon fibers, and excellent interfacial adhesion can be exhibited.

  In particular, it is an ester compound of a compound having an epoxy group at both ends of the molecule and an unsaturated monobasic acid because it excels in developing interfacial adhesion, and is unsaturated at one end of the molecular main chain. A compound having a group and having an epoxy group at the other end is preferred. By using such a compound (A), the radical polymerization resin and the carbon fiber can be strongly bonded, and excellent interfacial adhesiveness can be expressed.

  As the compound having an epoxy group at both ends of the molecule, it is particularly preferable to use one or both of a bisphenol diepoxy compound and a bisphenol alkylene oxide addition diepoxy compound. That is, the compound (A) is an ester of either one or both of a bisphenol diepoxy compound and a bisphenol alkylene oxide addition diepoxy compound and an unsaturated monobasic acid, and is at one end of the molecular main chain. It is preferable that the compound has an unsaturated group at the other end and an epoxy group at the other end. In the present invention, as the compound (A), one type of ester compound may be used alone, or two or more types of ester compounds may be used in combination.

<Compound (B)>
The sizing agent for carbon fiber of the present invention contains a bifunctional type urethane acrylate oligomer (B) (hereinafter referred to as “compound (B)”).

  The compound (B) has an effect of improving the interfacial adhesion between the matrix resin and the carbon fiber by forming an interface phase having excellent flexibility at the interface between the matrix resin and the carbon fiber. In addition, as a matrix resin for fiber reinforced composite materials, many radical polymerization resins such as vinyl ester resins and unsaturated polyester resins have low toughness. Interfacial adhesion is improved.

  In addition, when the carbon fiber to which the sizing agent is adhered and the matrix resin are combined, the sizing agent component on the surface of the carbon fiber diffuses into the matrix resin, and the sizing agent component is increased in the matrix resin particularly near the interface. A region included in the concentration is formed. This region affects the mechanical properties of the composite material. And since a compound (B) is a urethane acrylate oligomer, when forming a fiber reinforced composite material, it will be integrated in the hardening reaction of a matrix resin, and integration of an interface phase and a matrix resin phase will be aimed at. Therefore, by including this compound (B), even when the radical polymerization resin is used as a matrix resin, the mechanical properties of the fiber reinforced composite material are at the same level as when the epoxy resin is used as a matrix resin. can do.

  The compound (B) preferably has a cured product having a tensile elongation of 40% or more determined by the following measurement method. This tensile elongation is more preferably 45% or more, and more preferably 50% or more, since the effect of increasing the toughness of the interfacial phase is excellent. The upper limit of the tensile elongation rate (%) is preferably 900% or less, more preferably 700% or less in consideration of a significant reduction in the elastic modulus of the resin near the interface.

  The compound (B) needs to be bifunctional. If it is a tri- or higher functional type, the crosslink density becomes too high and sufficient toughness is not exhibited. On the other hand, in the monofunctional type, the crosslinking reaction with the matrix resin is only on one side, and a sufficient toughening effect cannot be obtained.

Further, since the effect of improving the toughness of the interfacial phase is great, the compound (B) preferably has a viscosity at 60 ° C. of 5,000 mPa · s or more and a cured product having a tensile strength of 6 MPa or more. A large viscosity indicates that the molecular weight of the oligomer is large or that the cohesive force between oligomer molecules is large. When the molecular weight is large or the cohesive force between the molecules is large, the compound (B) is unevenly distributed in the interfacial phase between the carbon fiber surface and the matrix resin without diffusing into the matrix resin, resulting in the effect of the interfacial phase. It is preferable because it can be made flexible. In addition, the tensile strength and tensile elongation rate of hardened | cured material can be calculated | required with the following measuring methods.
<Measurement method of tensile strength and tensile elongation of cured product>
1) A mixture of 97 g of urethane acrylate oligomer (B) and 3 g of a curing agent (2-hydroxy-2-methyl-1-phenyl-propan-1-one) is applied on a glass plate to obtain a film having a thickness of 100 μm. The coating is cured by irradiating with ultraviolet rays for 5 seconds from a position 10 cm away from the coating using an ozone type lamp (80 W / cm).

  2) Using the cured film, in accordance with JIS K7127 (test piece type 5), the tensile strength and the tensile elongation are measured at a tensile speed of 300 mm / min.

  The viscosity of the compound (B) at 60 ° C. is more preferably 10,000 mPa · s or more, and further preferably 20,000 mPa · s or more. As the upper limit of the viscosity, the one not solid at 60 ° C. is superior from the viewpoint of the preparation of the sizing agent and the temporal stability of the sizing agent. The viscosity of the compound (B) can be measured with a B-type viscometer.

  The glass transition temperature (Tg) of the cured product of the compound (B) contained in the sizing agent for carbon fiber of the present invention is preferably −5 ° C. or higher, and more preferably 5 ° C. or higher. If the Tg of the cured product is −5 ° C. or more, not only can the appropriate softening be achieved by the interfacial phase, but the value of the stress leading to fracture also increases, so that a stronger interfacial phase can be formed and the above effects are achieved. improves. That is, the interfacial phase has a function of supporting the reinforcing fiber, and it becomes easy to keep the mechanical properties of the composite material favorable by appropriately suppressing the softening. As an upper limit of Tg of hardened | cured material, when the function as a flexible component is considered, 100 degrees C or less is preferable and 80 degrees C or less is more preferable.

  Tg of the cured product of urethane acrylate oligomer is 2 ° C. using a viscoelasticity measuring apparatus (manufactured by UBM, product name: Rheogel E4000) using a cured film obtained by the same method as the measurement of tensile elongation rate as a test piece. The temperature is raised at a rate of / min, the dynamic viscoelasticity and loss tangent of the test piece are measured, and the peak temperature (tan δMAX) of the loss tangent can be obtained.

  In the present invention, the “urethane acrylate oligomer” is a compound having a urethane bond and an acryloyl group (CH 2 ═CH—CO—) in the molecule. The structure of the urethane acrylate oligomer can be broadly classified into an aromatic type having an aromatic group in the structure and an aliphatic type having no aromatic group. The structure of the urethane acrylate oligomer used in the present invention is not particularly limited, and may be aromatic or aliphatic. Since the balance between the tensile elongation percentage and the tensile strength of the cured product is good, an aliphatic system is preferable.

As the compound (B) contained in the sizing agent for carbon fiber of the present invention, commercially available urethane acrylate oligomers may be used. Examples of such urethane acrylate oligomers include CN-965 and CN-981 manufactured by Sartomer. CN-9178, CN-9788, CN-9893, CN-971, CN-973, CN-9882, UF-8001 made by Kyoeisha Chemical, UA-122P made by Shin-Nakamura Chemical Co., Ltd. Name).
In this invention, a compound (B) may be used individually by 1 type, and may use 2 or more types together.

<Contents of Compound (A) and Compound (B)>
In the sizing agent of the present invention, the content ratio (mass ratio) of the compound (A) and the compound (B) is within the range of compound (B) / compound (A) = 1/3 to 2/1. It is necessary to be. When the content of the compound (B) is less than 1/3 of the content of the compound (A), the interfacial phase is not sufficiently softened and toughened. On the other hand, when the content exceeds 2/1, the compound ( The good adhesion expression effect which is a function of A) is inhibited, and the effect of improving the adhesion of carbon fibers to the matrix resin cannot be sufficiently obtained. The ratio of the content of the compound (A) and the compound (B) is preferably compound (B) / compound (A) = 1/2 to 3/2, more preferably 2/3 to 1/1. .

  Moreover, in the sizing agent of this invention, it is necessary for the ratio of the total amount of the compound (A) and compound (B) which occupies in all the sizing components to be 20 mass% or more. If it is less than 20% by mass, the functions of these two components are not sufficiently exhibited, and the effects of the present invention cannot be obtained.

  Here, the “total sizing component” is the total amount of all components applied to the carbon fiber after the sizing treatment among the components contained in the sizing agent, and is removed after sizing, such as water or an organic solvent. Represents an active ingredient not included. That is, the “all sizing components” include the above-described compound (A) and compound (B), stearic acid ester compound (C) and surfactant (D) described later, and ester compound (E) described later as an optional component. , And the total amount with other components. The ratio of the total amount of the compound (A) and the compound (B) is preferably 25% by mass or more, and more preferably 30% by mass or more in all sizing components.

<Compound (C)>
The sizing agent for carbon fiber of the present invention contains a stearic acid ester compound (C) (hereinafter referred to as “compound (C)”) as an essential component. The compound (C) is a stearic acid ester compound and can improve the smoothness of the carbon fiber bundle.

  As stearic acid ester compounds, esters of stearic acid and various alcohols can be used, but methyl stearate, ethyl stearate, propyl stearate, butyl stearate, octyl stearate, stearyl stearate, oleyl stearate, tridecyl Stearate, hexadecyl stearate, ethylhexyl stearate, etc. are preferably used.

  In the sizing agent for carbon fiber of the present invention, the proportion of the compound (C) in all sizing components is preferably 5% by mass or more and 30% by mass or less. If it is 5 mass% or more, good smoothness can be imparted to the carbon fiber bundle. If it is 30% by mass or less, even when applied to a large tow, the convergence is not excessively lowered, good handleability is easily obtained, and the adhesion with the matrix resin is not hindered. Strength can be obtained. The proportion of the compound (C) in all sizing components is preferably 7% by mass or more and 25% by mass or less, and more preferably 10% by mass or more and 20% by mass or less.

<Compound (D)>
The sizing agent of the present invention preferably further contains a surfactant (D) (hereinafter referred to as “compound (D)”). The compound (D) is used to disperse the compound (A), the compound (B) and the compound (C) described above, the compound (E) which is an optional component described later, and other components in water. . A compound (D) may be used individually by 1 type, and may use 2 or more types together.

  Examples of the compound (D) contained in the carbon fiber sizing agent of the present invention include nonionic surfactants and anionic surfactants. As the nonionic surfactant, for example, a surfactant such as an aliphatic nonion and a phenol nonionic can be used. Aliphatic nonionic surfactants include higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid esters ethylene oxide adducts, glycerol fatty acid esters, sorbitol and sorbitan fatty acid esters, and pentaerythritol fatty acid esters. Etc. Examples of the phenol-based nonionic surfactant include alkylphenol-based nonions and polycyclic phenol-based nonions.

  Further, as the ethylene oxide adduct, a type in which a propylene oxide unit is provided in a part of the polyethylene oxide chain in a random or block form is preferable. As the fatty acid ethylene oxide adduct or polyhydric alcohol fatty acid ester ethylene oxide adduct, nonionic surfactants such as monoester type, diester type, triester type, and tetraester type can be used.

  As the compound (D) contained in the carbon fiber sizing agent of the present invention, an anionic surfactant having an ammonium ion as a counter ion (hereinafter, abbreviated as “(D-1) component” as appropriate), and a nonion described later It is preferable to contain a system surfactant (hereinafter abbreviated as “component (D-2)” as appropriate).

  The component (D-1) which is an anionic surfactant having an ammonium ion as a counter ion has a hydrophobic group and an ammonium ion as a counter ion, so that the sizing agent for carbon fiber of the present invention is an aqueous dispersion. This improves the stability of the carbon fiber and the wettability of the carbon fiber surface to the resin. The component (D-2) has an effect of suppressing the reaction activity between the ammonium ion of the component (D-1) and the epoxy group of the compound (A). Therefore, by containing appropriate amounts of the components (D-1) and (D-2) (contents will be described in detail later), the impregnation properties of various matrix resins are further improved and treated with a sizing agent. The change with time of the hardness of the carbon fiber formed can be made extremely small.

  The component (D-1) is not particularly limited, and examples thereof include carboxylate, sulfate ester salt, sulfonate salt, and phosphate ester salt. Among these, sulfate ester salts and sulfonate salts are more preferable because they are particularly excellent in the ability to emulsify the compound (A) and the compound (B).

  Examples of the sulfate ester salt include higher alcohol sulfate ester salt, higher alkyl polyethylene glycol ether sulfate ester salt, alkylbenzene polyethylene glycol ether sulfate ester salt, polycyclic phenyl ether polyethylene glycol ether sulfate ester salt, and sulfated fatty acid ester salt. . In addition, propylene oxide units are randomly or block-containing in part of the polyethylene oxide chain in the higher alkyl polyethylene glycol ether sulfate, alkylbenzene polyethylene glycol ether sulfate, and polycyclic phenyl ether polyethylene glycol ether sulfate. Can also be used.

  Examples of the sulfonate include alkylbenzene sulfonate, alkyl naphthalene sulfonate, polycyclic phenyl ether sulfonate, alkyl sulfonate, α-olefin sulfonate, α-sulfonated fatty acid salt, dialkyl sulfosuccinate, and the like. Is mentioned.

  In particular, an anionic surfactant having a hydrophobic group represented by the following general formula (1) or (2) is more preferably used as the component (D-1).

  In carbon fiber reinforced composite materials, it is desired to exhibit excellent mechanical properties by combining carbon fibers and a matrix resin. Therefore, some matrix resins have an aromatic skeleton in terms of rigidity. Mainly used in carbon fiber sizing agents, a compound having an aromatic skeleton is often used as a main component. Since the hydrophobic group represented by the general formula (1) or (2) has a high affinity with an aromatic substance, it is represented by the general formula (1) or (2) as the component (D-1). By containing an anionic surfactant having a hydrophobic group in the sizing agent for carbon fiber, the emulsified state is stabilized, and good storage results and good results in production and processes at the time of carbon fiber production are obtained. Further, the compatibility between the sizing agent and the matrix resin is improved, and the effects of the present invention, particularly the mechanical properties improving effect, are further improved.

  In addition, the anionic surfactant having a hydrophobic group represented by the general formula (1) or (2) is a relatively nonionic phenol type or octylphenol type from the viewpoint of preventing the diffusion of the exogenous endocrine disrupting substance derivative. This is also preferable because it has been desired to avoid the use of an anionic surfactant having a phenol group having a long alkyl group.

In the general formulas (1) and (2), R ₁ is a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 3 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, A hydrogen atom or a methyl group is further preferred, and a hydrogen atom is more preferred from the viewpoint of an exogenous endocrine disruptor derivative. R ₂ and R ₃ are a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 3 carbon atoms, and may be the same or different. Examples of the chain hydrocarbon group for R ₂ and R ₃ include the same chain hydrocarbon groups as those for R 1. R ₄ is a divalent aliphatic hydrocarbon group, and examples thereof include a linear or branched alkylene group having 1 to 10 carbon atoms. m represents a positive integer, preferably an integer of 1 to 3, and more preferably 1 or 2. If m is 3 or less, the hydrophobic group itself can be easily prevented from becoming a bulky structure, and the affinity and compatibility with the compound (A), the compound (B), and the matrix resin can be improved. Is easy. As a result, it is easy to improve the stability of emulsification, the resin impregnation property, and the mechanical properties of the fiber-reinforced composite material. A group in parentheses with a subscript m is a benzyl group (a group in which both R ₂ and R ₃ are hydrogen atoms) or a styrene group (R ₂ and R ₂ ) from the viewpoint of the bulkiness of the hydrophobic group molecule. It is preferable that one of ₃ is a hydrogen atom and the other is a methyl group. Moreover, when m is 2 or more, that is, when there are a plurality of groups in parentheses with a subscript m, these groups may be the same or different.

  Moreover, a commercial item can be used as surfactant (D).

  Examples of nonionic surfactants include “New Coal 707”, “New Coal 723”, and “New Coal 707-F” manufactured by Nippon Emulsifier Co., Ltd.

  Examples of the anionic surfactant (component (D-1)) include “New Coal 707-SF” and “New Coal 723-SF” manufactured by Nippon Emulsifier Co., Ltd., “Hitenol manufactured by Daiichi Kogyo Seiyaku Co., Ltd. NF-13 "," Hitenol NF-17 ", etc. (all are product names).

  The nonionic surfactant (component (D-2)) is not particularly limited, but an aliphatic nonionic surfactant is preferred because the reaction activity reducing action is extremely excellent. Aliphatic nonionic surfactants include higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid esters ethylene oxide adducts, glycerol fatty acid esters, sorbitol and sorbitan fatty acid esters, and pentaerythritol fatty acid esters. Etc. In these ethylene oxide adducts, a type in which propylene oxide units are randomly or block-containing in a part of the polyethylene oxide chain is also preferably used.

  As higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, those containing propylene oxide units randomly or in blocks in part of these polyethylene oxide chains are more preferred. . This is because these are excellent in the ability to reduce the reaction activity of ammonium ions on epoxy groups. As the fatty acid ethylene oxide adduct and polyhydric alcohol fatty acid ester ethylene oxide adduct, monoester type, diester type, triester, tetraester type and the like can be used.

  Moreover, a commercial item can also be used for (D-2) component, for example, "Fine Surf FON180E06 (product name)" by Aoki Yushi Co., Ltd. is mentioned.

The content of the compound (D) can be appropriately determined in consideration of the stability of the aqueous dispersion in which the sizing agent is dispersed in water and the sizing effect of the sizing agent. -30 mass% is preferable, and 10-25 mass% is more preferable. If the surfactant content is 5% by mass or more, it is easy to improve the stability of the aqueous dispersion in which the sizing agent is dispersed in water, and if it is 30% by mass or less, the effect of the sizing agent is achieved. Is easy to express.
<Contents of (D-1) component and (D-2) component>
When the sizing agent of the present invention contains the component (D-1) and the component (D-2), the ratio (mass ratio) of the content of the component (D-1) and the component (D-2) is , (D-2) component / (D-1) component = preferably within a range of 1/10 to 1/5.

  When the mass ratio is within this range, it becomes easy to suppress the reaction activity of the ammonium ion derived from the compound (D) to the epoxy group of the compound (A), and as a result, carbon to which a sizing agent is attached. It can suppress that the hardness of a fiber changes rapidly. Furthermore, the emulsification stability when the sizing agent is emulsified using water or the like as the medium, and the wettability of the sizing-treated carbon fiber surface to the resin are preferable.

Moreover, in the sizing agent of this invention, when it contains (D-1) component and (D-2) component, (D-1) component and (D-2) component which occupy in all the sizing components It is preferable that the ratio of the total amount of is 10-25 mass%. Within the above range, the emulsion stability of the sizing agent solution is very good, and it is easy to exert the effect of the sizing agent. The more preferable lower limit of the total amount of the component (D-1) and the component (D-2) is 13% by mass, and the more preferable upper limit is 20% by mass.
<Compound (E)>
The sizing agent for carbon fiber of the present invention is an ester compound of an alkylene oxide adduct of bisphenols and a dicarboxylic acid compound in addition to the above-described compounds (A) to (D), and has an acid value of 50. The ester compound (E) (hereinafter abbreviated as “compound (E)” as appropriate) may be contained.

  The compound (E) preferably has a molecular weight of about 1000 and has as its main constituent a compound having a carboxyl group at one end of the molecule. Such a compound (E) exhibits excellent compatibility with a matrix resin, particularly an epoxy resin or a vinyl ester resin, so that the wettability of the sized carbon fiber to the resin is improved and the resin impregnation property is further improved. .

  The “alkylene oxide adduct of bisphenols” is preferably a compound obtained by adding 2 to 4 moles of ethylene oxide or propylene oxide to 1 mole of bisphenols. When the addition amount of ethylene oxide or propylene oxide to 1 mol of bisphenols is 4 mol or less, it is easy to improve the affinity with the matrix resin without impairing the rigidity of the molecular chain inherent to bisphenols. . More preferably, bisphenols are added with 2 mol of ethylene oxide or propylene oxide. The alkylene oxide adducts of bisphenols may be used alone or as a mixture of a plurality of compounds.

  The “dicarboxylic acid compound” is preferably an aliphatic compound having 4 to 6 carbon atoms. When an aromatic compound is used as the dicarboxylic acid compound, the resulting ester compound has a relatively high melting point and tends to be relatively poor in solubility with the matrix resin. Use of an aliphatic compound as the dicarboxylic acid compound is preferable because the wettability of the matrix resin with respect to the carbon fibers is improved. When an aliphatic compound having 6 or less carbon atoms is used as the dicarboxylic acid compound, it is easy to improve the affinity with the matrix resin without impairing the rigidity of the resulting ester compound.

  Examples of the dicarboxylic acid compound include fumaric acid, maleic acid, methyl fumaric acid, methyl maleic acid, ethyl fumaric acid, ethyl maleic acid, glutaconic acid, itaconic acid, malonic acid, succinic acid, methyl succinic acid, glutaric acid, and adipic acid. It is done.

  As the compound (E) that can be added to the carbon fiber sizing agent of the present invention, one type may be used alone, or two or more types may be used in combination. In the sizing agent of the present invention, the ratio of the mass of the compound (E) to the total mass of the compound (A) and the compound (B) (compound (E) / [compound (A) + compound (B)]) It is preferable that it is 2.0 or less. When the ratio is 2.0 times or less, the interaction between the compound (A) and the carbon fiber surface is reduced by the interaction between the epoxy group of the compound (A) and the acidic group (carboxy group or the like) of the compound (E). Can be easily prevented. As a result, the coupling function of the sizing agent by the compound (A) is easily exhibited, and the adhesion between the carbon fiber and the matrix resin is good. This ratio is more preferably 1.75 or less, and further preferably 1.55 or less. The lower limit of this ratio is not particularly limited, but in order to exert the effect of the compound (E) that improves the wettability and resin impregnation property of the sized carbon fiber, 0.2 or more is more preferable. 0.4 or more is more preferable.

<Aqueous dispersion of carbon fiber sizing agent>
The aqueous dispersion of the sizing agent for carbon fiber of the present invention can be obtained by mixing and stirring (emulsifying and dispersing in water) each component by a conventional method. The sizing agent concentration (nonvolatile component concentration) in the aqueous dispersion, that is, the concentration of components other than the volatile components (such as water removed by drying after sizing) in the sizing aqueous dispersion is the concentration at which water exists as a continuous phase. If it is a range, it will not specifically limit, Usually, 10-50 mass% is used. There is no problem even if the concentration of the sizing agent is less than 10% by mass in the preparation stage of the sizing aqueous dispersion, but the proportion of water in the sizing aqueous dispersion increases, and it is used from the preparation of the sizing aqueous dispersion (of carbon fiber). It may become uneconomical in terms of transportation and storage until the sizing process). Therefore, when sizing the carbon fiber, the sizing water dispersion is diluted to about 0.1 to 10% by mass so that the amount of the sizing agent attached to the carbon fiber becomes a desired value. The method of making it adhere is common.

<Carbon fiber bundle with attached carbon fiber sizing agent>
The carbon fiber bundle that can be suitably used for the carbon fiber bundle (sizing-treated carbon fiber) to which the sizing agent for carbon fiber of the present invention is attached is obtained from any raw material such as pitch, rayon, or polyacrylonitrile. It may be any of a high strength type (low elastic modulus carbon fiber), a medium high elasticity carbon fiber, or an ultrahigh elasticity carbon fiber. The carbon fiber sizing agent can be attached by, for example, attaching a dispersion of the sizing agent to the carbon fiber by a roller dipping method or a roller contact method, and drying. From the viewpoint, the roller dipping method is preferable.

  The attached amount of the sizing agent in the carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is attached is preferably 0.6% by mass or more and 2.0% by mass or less with respect to the total mass of the carbon fiber and the sizing agent. 1.0% by mass or more and 1.6% by mass or less is more preferable. When the adhesion amount of the sizing agent is 0.6% by mass or more, it becomes easy to cover the entire carbon fiber surface with the sizing agent. Moreover, smoothness and convergence can be simultaneously imparted to the carbon fiber bundle. Furthermore, when the carbon fiber reinforced composite material is produced, when the sizing-treated carbon fiber and the matrix resin are mixed, the above-described interfacial resin layer can fully exhibit functions such as flexibility and toughness. it can. On the other hand, if the adhesion amount of the sizing agent is 2.0% by mass or less, the sizing treatment carbon fiber is easily handled and impregnated with the matrix resin as a result of the sizing treatment carbon fiber being hardened by depositing a large amount of the sizing agent on the carbon fiber surface. It is possible to easily suppress the deterioration of the property.

  Also, if the amount of sizing agent attached is within the above range, in the carbon fiber reinforced composite material, a failure occurs in the transmission of stress transmitted from the matrix resin to the sizing carbon fiber through the interface resin layer, resulting in a decrease in mechanical properties. Can be suppressed. In addition, if the amount of sizing agent is within the above range, the carbon fiber has excellent bundling properties and scratch resistance, and sufficient wettability to the matrix resin and interfacial adhesion between the matrix resin and the like. And the resulting carbon fiber reinforced composite material is provided with good mechanical properties.

  Note that the convergence of the carbon fiber bundle varies depending on the number of filaments, the fiber diameter, the surface wrinkles, and the like of the carbon fiber to be sized. In this invention, it can be set as the suitable convergence property by adjusting the ratio of each component in a sizing agent, or adjusting the adhesion amount of a sizing agent. The adhesion amount of the sizing agent can be adjusted by adjusting the sizing agent concentration of the sizing agent aqueous dispersion in the sizing process or adjusting the squeezing amount.

  The carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is attached has the above-mentioned sizing agent, so that the sizing agent does not easily accumulate on the fluff and the guides due to mechanical friction, etc. It also has excellent impregnation and adhesiveness.

  In particular, when the sizing agent contains the compound (E), it exhibits excellent compatibility with the matrix resin. Therefore, the wettability of the sized carbon fiber to the resin is improved, and the resin impregnation property is further improved.

(Sheet substrate)
The carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is attached is excellent in process passability such as weaving and can be suitably used for various sheet-like substrates. For example, a sheet-like substrate of a unidirectionally arranged sheet, a sheet-like substrate in the form of a woven fabric, or a plurality of sheet-like substrates in which a plurality of fiber bundles are arranged in parallel are included in each sheet-like substrate. Suitable for sheet-like substrates such as so-called multiaxial laminated knitted sheet substrates in which the direction of the tow-shaped carbon fiber bundle is laminated at different angles with respect to the reference direction and integrated with stitch yarns Can be processed. In particular, in processing to a woven fabric sheet-like base material or a multiaxial laminated knitted sheet-like base material, carbon fibers usually tend to generate fluff due to rubbing, but the carbon fiber bundle to which the sizing agent for carbon fibers of the present invention is attached. Can significantly suppress fuzz by the sizing agent.

(Carbon fiber reinforced resin composition, composite material including sheet-like substrate)
The carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is adhered and the sheet-like material of the present invention are combined with a matrix resin, and are unidirectional prepreg, woven prepreg, knitted prepreg, tow prepreg, short fiber reinforced resin impregnated sheet, short The carbon fiber reinforced resin composition can be configured in the form of a fiber mat reinforced resin impregnated sheet or the like. The matrix resin is not particularly limited, and examples thereof include epoxy resins, radical polymerization resins such as acrylic resins, vinyl ester resins, unsaturated polyester resins, thermoplastic acrylic resins, and phenol resins. .

  The carbon fiber reinforced resin composition can be produced by impregnating the above matrix resin into a carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is attached or a sheet-like substrate of the present invention. As a method for producing such a carbon fiber reinforced resin composition, a conventional method can be employed. For example, methods such as a hot melt method, an RTM method, a solvent method, a syrup method, or a thickening resin method used for a sheet mold compound (SMC) can be used.

  The carbon fiber reinforced resin composition using the carbon fiber bundle to which the sizing agent for carbon fiber of the present invention is attached or the sheet-like base material of the present invention has a matrix resin because the sizing treated carbon fiber is used as a reinforcing material. As well as epoxy resin, it is excellent in impregnation with radical polymerization resins such as acrylic resin, unsaturated polyester resin, vinyl ester resin, and phenol resin, and the interfacial adhesion between carbon fiber and matrix resin is strong and good. Dynamic characteristics may be exhibited.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this.

[Example 1]
(Preparation of sizing agent)
A sizing agent was prepared by phase inversion emulsification using a mixer (made by Tokushu Kika Kogyo Co., Ltd., product name: Hibis Disper Mix, homomixer specification: Model 3D-5).

  Components other than the component (D) in the types and blending amounts shown in the column of Example 1 in Table 1 were kneaded and mixed at 120 ° C. with a planetary mixer and a homomixer. Thereafter, the temperature was raised to 90 ° C. while kneading, and then an aqueous solution of component (D) was added little by little. During this process, the viscosity of the contents gradually increased. After all the aqueous solution of component (D) was charged, the temperature was set to 60 ° C. while kneading for 10 minutes. Next, deionized water was added dropwise little by little, and after passing through the phase inversion point, the amount of water dropped was increased. Finally, a sizing agent aqueous dispersion having a sizing agent concentration of about 40% by mass was obtained.

(Production of sizing treated carbon fiber and evaluation of process passability)
The carbon fiber to which the sizing agent for carbon fiber was attached was produced by the following procedure. An immersion tank having an immersion roller inside is filled with an aqueous dispersion of the above sizing agent adjusted to a concentration of 5.0%, and a carbon fiber bundle (Mitsubishi Rayon) to which no sizing agent is added in the aqueous dispersion. Product name: Pyrofil TRW40 50L, filament number 50,000, strand strength 4,100 MPa, strand elastic modulus 240 GPa, fiber density 1.81 g / cm3, fiber basis weight 3,750 mg / m) were immersed. Then, the carbon fiber bundle which the sizing agent adhered was obtained by making it contact for 60 seconds and heating to the heating roll with a surface temperature of 150 degreeC. The carbon fiber bundle was wound around a bobbin. Under the present circumstances, the sizing process process passability evaluation was performed in the process from a heat drying process to winding up to a bobbin. In the process from heat drying to winding on the bobbin, there is no fluffing, no fibers are wound around the roll between processes, and there is no adhesion of sizing-derived deposits to the fixed pin guide between processes Passability of the sizing process as x when the case is fluffy, fluff is generated, the fiber is wound around the roll between processes, or there is adhesion of sizing-derived deposits on the fixed pin guide between processes Evaluated. The results are shown in Table 1.

(Measurement of amount of sizing agent attached to carbon fiber bundle with sizing agent for carbon fiber attached)
The carbon fiber bundle to which the sizing agent for carbon fiber is attached is weighed (W1), and left in a muffle furnace (FP410 manufactured by Yamato Scientific Co., Ltd.) set at a temperature of 450 ° C. in a nitrogen stream of 50 liters / minute for 15 minutes. The sizing agent attached to the carbon fiber bundle is completely pyrolyzed. And it moved to the container in the dry nitrogen stream of 20 liters / minute, and the carbon fiber bundle after cooling for 15 minutes was weighed (W2), and the adhesion amount was calculated | required from following Formula. The results are shown in Table 1.
Amount of sizing agent attached (% by mass)
= [W1 (g) -W2 (g)] / [W1 (g)] × 100

(Preparation of multi-axial laminated knitted sheet-like substrate and evaluation of process passability)
Two unidirectional sheet-like base materials obtained as described above were laminated, and then integrated by stitch processing using polyester fibers. At this time, two unidirectional sheet-like base materials were laminated at + 45 ° / −45 ° with reference to the direction in which the stitch yarns continue. In this stitch processing step, process passability was evaluated. There is no accumulation of sizing agent on the surface of the stitch needle or adhesion of fluff, and there is no gap between the carbon fiber bundles in the obtained multiaxial laminated knitted sheet, and there is no fluff on the surface of the multiaxial laminated knitted sheet. ◎, the sizing agent is deposited on the surface of the stitch needle and fuzz adheres, or there is a gap between the carbon fiber bundles in the obtained multiaxial laminated knitted sheet, or on the surface of the multiaxial laminated knitted sheet. The thing without fluff was set as x. The results are shown in Table 1.

(Production of unidirectional carbon fiber reinforced composite material (epoxy resin) and 90-degree bending test)
54 g / m 2 per unit area on a release paper whose one side surface is release-treated with a matrix resin composed of a B-staged epoxy resin composition (manufactured by Mitsubishi Rayon Co., Ltd .: # 350; cured at 130 ° C.). And evenly applied. On the resin side of the resin-carrying sheet, the carbon fiber provided with the sizing agent obtained by the above-described method was attached by being aligned in one direction so that the fiber basis weight was 200 g / m2. Furthermore, the resin-side surface of the resin-carrying sheet coated with resin uniformly at 54 g / m 2 per unit area similar to the above from the carbon fiber side is overlapped with the carbon fiber woven fabric side, and these are laminated at 100 ° C., linear pressure: It was impregnated by heating under pressure at 2 kg / cm. Thereafter, the release paper on one side is peeled off, and a protective film is attached to the surface, whereby the carbon fiber basis weight is 200 g / m 2 and the resin content (hereinafter referred to as “RC”) is 35% by mass. A directional carbon fiber prepreg was prepared.

  The unidirectional carbon fiber prepreg is laminated with the orientation of the carbon fiber bundle aligned in one direction, and is heated and pressurized using an autoclave (from room temperature to 180 ° C for 2 hours, 180 ° C for 2 hours, pressure 0.6 MPa) A composite material having a thickness of 2 mm was prepared. The 90-degree bending strength of the composite material thus obtained was measured according to ASTM D790. The results are shown in Table 1.

(Production of unidirectional carbon fiber reinforced composite material (vinyl ester resin) and bending test at 90 degrees)
Using 34 carbon fiber bundles with sizing agent attached (number of inputs: 34), the carbon fiber bundles with sizing agent attached are unwound from the creel, arranged in a sheet form via a guide roll, and then guided to a resin bath. Then, after being immersed in a thermosetting resin VE described later and adhering the resin, it was impregnated by rubbing with a guide bar and excessive resin was removed to some extent. Thereafter, the resin was introduced into a pultrusion mold having a drawing passage having a rectangular cross section of 2 mm × 50 mm, and finally excess resin was removed. The mold temperature of the pultrusion mold 6 was 155 ° C., and the molding speed was 0.25 m / min.

Here, the thermosetting resin VE1 used for the pultrusion molding is as follows.
“VE1”: main agent (manufactured by DIC, product name: DICLITE UE-3505), curing agent (manufactured by Kayaku Akzo, product name: Trigonoks 117), and curing accelerator (manufactured by NOF Corporation, product name: Parroyl) PCT) and internal mold release agent (manufactured by AXEL, product name: Mold with PS-125), mass of main agent / curing agent / effect accelerator / internal mold release agent = 100/2 / 0.75 / 1. Mixed by ratio.

  The 90 degree direction bending strength of the pultruded product obtained above was measured according to ASTM D790. The results are shown in Table 1.

[Examples 2 to 9]
The sizing agent was prepared and evaluated in the same manner as in Example 1 except that the composition shown in Table 1 was used. The results are shown in Table 1.

[Example 10]
The concentration in the immersion tank was prepared and evaluated in the same manner as in Example 1 except that the concentration of the aqueous dispersion of the sizing agent was 3.0%. The results are shown in Table 1.

[Example 11]
The concentration in the immersion bath was prepared and evaluated in the same manner as in Example 1 except that the concentration of the aqueous dispersion of the sizing agent was 10.0%. The results are shown in Table 1.

[Comparative Examples 1-4]
The sizing agent was prepared and evaluated in the same manner as in Example 1 except that the composition shown in Table 2 was used. The results are shown in Table 2.

[Comparative Example 5]
The concentration in the immersion bath was prepared and evaluated in the same manner as in Example 1 except that the concentration of the aqueous dispersion of the sizing agent was 1.0%. The results are shown in Table 2.

[Comparative Example 6]
The concentration in the immersion bath was prepared and evaluated in the same manner as in Example 1 except that the concentration of the aqueous dispersion of the sizing agent was 15.0%. The results are shown in Table 2.

  The components shown in Tables 1 to 3 are shown in detail in Table 4, respectively. Catalog values were adopted for the tensile elongation and glass transition temperature (Tg) of the cured product of urethane acrylate oligomer.

  More specifically, A1 to A2 and E1 to E3 in Table 3 are synthetic products obtained by the following procedures, respectively.

(A) component, one-end acrylic acid-modified diglycidyl ether bisphenol A
Here, in A1 to A2, the half ester component effective as the component (A) is 1/2, and the remaining 1/2 is an unreacted product and a diester product. The compounding amounts of A1 to A2 shown in Tables 1 to 3 represent the total amount of the half ester component, the unreacted product, and the diester product. Therefore, the active ingredient amount as a half ester is 1/2 of the compounding amount of Tables 1-3. That is, when calculating the content of the component (A) in the sizing agent, a value that is half the blending amount of A1 and A2 shown in the table is used. However, the amount of all sizing components includes not only the blending amount of the half ester component but also the blending amounts of the unreacted product and the diester product. That is, in order to calculate the amount of all sizing components, the values of the blending amounts of A1 and A2 shown in the table are used.

  A1: To 378 parts by mass of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin, product name: JER828), 86 parts by mass of acrylic acid, 1 part by mass of hydroquinone, and 1 part by mass of lithium chloride were added and heated at 100 ° C. The obtained mixture of JER828 / JER828 one-end acrylic modified epoxy resin (half ester) / JER828 both-end acrylic modified epoxy resin (diester) at a mixing mass ratio of 1/2/1.

  A2: Addition of 86 parts by mass of acrylic acid, 1 part by mass of hydroquinone, and 1 part by mass of lithium chloride to 1000 parts by mass of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin, product name: JER834). The obtained mixture of JER834 / JER834 one-end acrylic modified epoxy resin (half ester) / JER834 both-end acrylic modified epoxy resin (diester) at a mixing mass ratio of 1/2/1.

(E) Component, polyester production method E1: PO adduct of bisphenol A in which 3 mol of PO (propylene oxide) is added to 1 mol of bisphenol A (manufactured by Sanyo Chemical Co., Ltd., product name: Newpol BP-3P) ) 800 parts by mass, 278 parts by mass of fumaric acid (alcohol / acid = 1 / 1.2 molar ratio) and 1 part by mass of tetraisopopropoxy titanate in a glass reaction vessel at 180 ° C. under nitrogen flow at −0.1 MPa (gauge The reaction was carried out for 10 hours while distilling off water.

  E2: PO adduct of bisphenol A (product name: New Pole BP-3P, manufactured by Sanyo Chemical Industries, Ltd.) in which PO3 mol part is added to 1 mol part of bisphenol A, 139 parts by mass of fumaric acid (alcohol / Acid = 1 / 1.2 molar ratio) and 1 part by mass of tetraisopopropoxy titanate were reacted in a glass reaction vessel for 10 hours while distilling off water at 180 ° C. under nitrogen flow. Further, 668 parts by mass of EO addition product of bisphenol A (manufactured by Sanyo Chemical Industries, Ltd., product name: New Pole BPE-100) in which 10 mol of EO (ethylene oxide) was added to 1 mol of bisphenol A was added at 180 ° C. The pressure was reduced to -0.1 MPa (gauge pressure) and the reaction was performed for 10 hours while distilling off water.

  E3: 800 parts by mass of bisphenol A PO adduct (manufactured by Sanyo Kasei Kogyo Co., Ltd., product name: Newpol BP-3P) in which PO 3 mol part is added to 1 mol part of bisphenol A, 232 parts by mass of fumaric acid (alcohol / Acid = 1/1 molar ratio) and 1 part by mass of tetraisopopropoxy titanate were reacted in a glass reaction vessel for 10 hours while distilling off water at 180 ° C. under nitrogen flow. Further, 668 parts by mass of EO addition product of bisphenol A (manufactured by Sanyo Chemical Industries, Ltd., product name: New Pole BPE-100) in which 10 mol parts of EO are added to 1 mol part of bisphenol A is added at -0.1 MPa at 180 ° C The pressure was reduced to (gauge pressure) and the reaction was carried out for 10 hours while distilling off water.

As shown in the above results, the carbon fiber bundle in the case where the sizing agent of the present invention was applied as in Examples 1 to 11 generated fluff in the process from the heat drying treatment after the sizing treatment to the winding up on the bobbin. There was no wrapping of fibers around the roll between the processes, and there was no adhesion of deposits derived from the sizing agent to the fixed pin guide between processes, and the process passage was very stable. In addition, when a unidirectional sheet-like substrate is prepared using a carbon fiber bundle to which the sizing agent of the present invention is applied, there is no collapse or thread breakage during unwinding from the bobbin, and sizing on the surface of the metal rod There is no deposition or fluffing of the agent, the process passability is very stable, and there is no gap between the carbon fiber bundles in the obtained unidirectional sheet-like substrate, and there is no fluff on the surface of the sheet-like substrate, It was excellent in appearance quality. Even when a multiaxial laminated knitted sheet-like substrate is created, there is no sizing agent accumulation or fuzz adhesion on the stitch needle surface, the process passability is very stable, and the obtained multiaxial laminated knitted sheet form The base material had no gaps between the carbon fiber bundles, had no fluff on the surface of the multiaxial laminated knitted sheet, and was excellent in appearance quality. Furthermore, all of the pultruded composite materials obtained using the carbon fiber bundles to which the sizing agent of the present invention was applied had excellent adhesiveness with the radical polymerization resin.

Claims (7)

A sizing agent for carbon fiber that satisfies the following (1) to (4).
(1) The carbon fiber sizing agent contains the following (A) to (D).
-An ester compound of an epoxy compound having a plurality of epoxy groups in the molecule and an unsaturated monobasic acid, and a compound having at least one epoxy group in the molecule (A)
-Bifunctional urethane acrylate oligomer compound (B) with a tensile elongation of the cured product of 40% or more
・ Stearic acid ester compound (C)
・ Surfactant (D)
(2) The mass ratio of the content of the compound (A) and the urethane acrylate oligomer (B) is 1/3 or more and 2/1 or less as the ratio of urethane acrylate oligomer (B) / compound (A).
(3) The ratio of the total amount of the compound (A) and the urethane acrylate oligomer (B) in all sizing components is 20% by mass or more.
(4) The proportion of the stearic acid ester compound (C) in all sizing components is 5% by mass or more and 30% by mass or less. The sizing agent for carbon fibers according to claim 1, which satisfies the following (5) and (6).
(5) An ester of an alkylene oxide adduct of bisphenols and a dicarboxylic acid compound, the ester compound (E) having an acid value of 50 or more.
(6) Content of the said ester compound (E) is 2.0 mass times or less of the total amount of the said compound (A) and the said urethane acrylate oligomer (B). The sizing agent for carbon fibers according to claim 1 or 2, which satisfies the following (7) and (8).
(7) The surfactant (D) contains an anionic surfactant (D-1) having an ammonium ion as a counter ion and a nonionic surfactant (D-2), and the anionic surfactant The mass ratio of the content of the agent (D-1) and the nonionic surfactant (D-2) is a ratio of nonionic surfactant (D-2) / anionic surfactant (D-1). In the range of 1/10 to 1/5.
(8) The ratio of the total amount of the anionic surfactant (D-1) and the nonionic surfactant (D-2) in all sizing components is 10% by mass or more and 25% by mass or less.   The carbon fiber bundle which consists of carbon fiber to which the said sizing agent for carbon fibers adhered, Comprising: The adhesion amount of this sizing agent is 0.6 to 2.0 mass%, Any one of Claims 1-3 The carbon fiber bundle according to one item.   The sheet-like base material containing the carbon fiber bundle of Claim 4.   A carbon fiber reinforced composite material comprising the carbon fiber bundle according to claim 4.   A carbon fiber reinforced composite material comprising the sheet-like substrate according to claim 5.