JP2000355884A - Sizing agent for carbon fiber, sizing agent solution for carbon fiber, carbon fiber, carbon fiber sheetlike material using the carbon fiber and carbon fiber- reinforced resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carbon fiber having excellent resin impregnation not only into an epoxy resin but also into a radical polymerization-based resin by imparting a compound containing a specific functional group and an epoxy group as a sizing agent to a carbon fiber and a carbon fiber reinforced resin composition by using the carbon fiber as a reinforcing fiber. SOLUTION: A compound containing a functional group of formula I (R is H or an alkyl) and an epoxy group of formula II, preferably a glycidyl group at the molecular main chain ends, respectively is dispersed into water to give a sizing agent solution. A carbon fiber is coated with 0.1-5 wt.% of the sizing agent solution and sized. The sized carbon fiber is arranged in one direction to give a sheetlike material, which is subjected to heat fusion treatment with a heat fusing fiber at fixed intervals in the direction perpendicular to the arrangement direction. Otherwise, a heat fusing fiber cloth is laminated and heat fused to at least one side of the sheetlike material to give the objective carbon fiber sheetlike material for a carbon fiber reinforced resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a carbon fiber sheet or carbon fiber reinforced resin composition, a carbon fiber used for the same, and a sizing agent and a sizing solution thereof.

[0002]

2. Description of the Related Art Conventionally, as one of fiber reinforced composite materials, there is a carbon fiber reinforced resin composition composed of carbon fiber and resin.
As the matrix resin constituting the carbon fiber reinforced resin composition, various resins such as radically polymerizable resins such as an unsaturated polyester resin, a vinyl ester resin, and an acrylic resin are used in addition to an epoxy resin generally widely used. Have been. On the other hand, the carbon fiber used in this carbon fiber resin is a fiber whose most chemical composition (90% or more) is made of carbon, and is obtained from regenerated cellulose, polyacrylonitrile (PAN), pitch, etc., and has a high strength. It is classified into carbon fiber, high elastic carbon fiber and the like. This carbon fiber is lightweight and has particularly excellent properties with respect to specific strength and specific elastic modulus. In addition, since it has excellent heat resistance and chemical resistance, it is effective as a reinforcing agent and is widely used.

[0003] However, this carbon fiber is a brittle material having a low elongation, and thus has a disadvantage in that, when used, the carbon fiber is liable to bevel due to mechanical friction or the like. In addition, since carbon fibers generally have poor adhesion to a matrix resin, there is a disadvantage that it is difficult to sufficiently exhibit the excellent properties of carbon fibers in a carbon fiber reinforced resin composition using the same. In order to reduce these inconveniences, carbon fibers have been conventionally treated with a sizing agent. The sizing agent for carbon fiber is used to improve the handleability of the carbon fiber, and also to improve the adhesiveness to the matrix resin and to improve the properties of the carbon fiber reinforced resin. It has properties such as improving the impregnation of carbon fibers and improving the adhesiveness. As a sizing agent used for such a carbon fiber, for example, one using polyglycidyl ethers or the like (see Japanese Patent Publication No. 57-15229) (hereinafter abbreviated as “sizing agent 1”), molecular Having, as a main component, a reaction product of an epoxy compound having at least three epoxy groups therein and a vinyl group-containing carboxylic acid (see:
Various types have been proposed such as JP-A-55-84476 (hereinafter abbreviated as "sizing agent 2"). The sizing agent 1 has advantages such as excellent impregnation and interfacial adhesive strength when used. The sizing agent 2 can improve the adhesiveness with a matrix resin, especially an unsaturated polyester resin, and when the epoxy resin is used as the matrix resin, the physical properties of the carbon fiber reinforced resin composition fluctuate due to fluctuations in curing conditions. It is an excellent sizing agent that can reduce the conventional concern of sizing.

[0004]

However, the sizing agent 1 does not have sufficient adhesiveness to radically polymerizable resins such as unsaturated polyester resins, vinyl ester resins, and acrylic resins, and carbon fibers using these resins as matrix resins are not sufficient. It is unsuitable for use in fiber reinforced resin compositions. The sizing agent 2 may not always have one or more epoxy groups and vinyl groups in the molecule, and there is a possibility that these functional groups may be present at either the main terminal or the branched terminal. In addition, there is a risk that stable physical properties cannot be expected, such as the bulkiness as a molecule is large, and a crosslinked network is easily formed between the carbon fiber and the matrix resin interface layer.

The present invention has been made in order to solve the above-mentioned problems, and has a good resin impregnating property not only with an epoxy resin but also with a radical polymerizable resin such as an acrylic resin, an unsaturated polyester resin and a vinyl ester resin. In addition, the carbon fiber, carbon fiber sheet-like material and carbon fiber reinforced resin composition using the carbon fiber as a reinforcing material, which are excellent in the adhesive strength between these resins and carbon fiber, and furthermore, provide a stable property improving effect, A sizing agent for carbon fibers and the like are provided for that purpose.

[0006]

The sizing agent for carbon fibers of the present invention comprises a compound having a functional group represented by the following general formula (1) and an epoxy group represented by the following general formula (2). It is a feature.

Embedded image (In the general formula (1), R is a hydrogen atom or an alkyl group.) Here, the compound has a functional group represented by the general formula (1) and an epoxy group represented by the general formula (2). It is desirable to have one by one, and each of these functional groups is located at one end of the main chain. Further, the epoxy group is preferably a glycidyl group represented by the following general formula (3).

Embedded image

The carbon fiber of the present invention is characterized in that the above-mentioned sizing agent for carbon fiber is adhered thereto. The amount of the carbon fiber sizing agent attached is 0.1
To 5% by weight. The sizing agent solution for carbon fibers according to the present invention is characterized in that the sizing agent for carbon fibers described above is dispersed in an aqueous solution. The carbon fiber sheet according to the present invention comprises the above carbon fiber. As the carbon fiber sheet-like material, one in which carbon fibers are aligned in one direction is desirable. As the carbon fiber sheet, heat fusible fibers are arranged at predetermined intervals on at least one surface of the carbon fiber sheet along a direction perpendicular to the carbon fibers aligned in one direction. It is preferable that the heat-fusible fiber cloth is heat-sealed on at least one surface thereof.

[0008] The carbon fiber sheet-like woven fabric of the present invention is characterized by having the carbon fiber as a woven yarn. At this time, it is desirable that carbon fibers be warps and fibers having a lower tensile modulus than the warp be wefts. Further, the weft is a composite yarn composed of two kinds of fibers having a melting point difference of 50 ° C. or more and a weight per 1 m of 0.1 g or less, the spacing between the wefts in the radial direction is 3 to 15 mm, and the low melting point fiber of the weft is used. Thus, a carbon fiber sheet-like woven fabric in which a warp and a weft are bonded to each other is desirable. The carbon fiber reinforced resin composition of the present invention has the above carbon fiber. Here, it is desirable that the carbon fibers are aligned in one direction. Further, a carbon fiber reinforced resin composition having the above-described carbon fiber sheet woven fabric is desirable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The sizing agent for carbon fibers of the present invention has the general formula (1)
And a compound having an epoxy group represented by the general formula (2). The compound is not particularly limited as long as it is a compound having a functional group represented by the general formula (1) and an epoxy group represented by the general formula (2) in a molecule, and for example, represented by the following general formulas (4) to (9) Are preferably used.

Embedded image (N in the general formulas (8) and (9) is 2 to 7.)

In such a compound, the double bond of the above functional group (1) reacts with the radical polymerizable resin by radical reaction to form a bond, and the epoxy group physically or chemically bonds with the active group on the carbon fiber surface. To form R of functional group (1)
Is preferably a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, and a suitable one is selected according to the type of the resin to be the matrix resin. Among compounds having a functional group represented by the general formula (1) and an epoxy group represented by the general formula (2) in a molecule, compounds represented by the general formulas (4) to (9) include: It is preferable that a functional group represented by the general formula (1) is disposed at one end of the main chain of the molecule, and an epoxy group represented by the general formula (2) is disposed at the other end. By adopting such a molecular structure, the carbon fiber is more strongly bonded to a matrix resin, for example, a radical polymerizable resin such as an unsaturated polyester resin, a vinyl ester resin, and an acrylic resin.

In the present invention, the epoxy group is represented by the general formula (2), but the glycidyl in the compound represented by the general formula (4) or the general formulas (5) to (9) is used. The ether form is preferred because it exhibits better interfacial adhesion. Further, in the skeleton of the compound, for example, the general formulas (4), (5),
(6) bisphenol A type such as the compound represented by the general formula (8), or bisphenol F type such as the compound represented by the general formula (7) or (9), or bisphenol S And biphenyl types. Since this bisphenol A type or bisphenol F type has a relatively rigid structure, a sizing agent containing the above compound as a main component having this as a skeleton gives good mechanical properties to carbon fibers. be able to. Also, this bisphenol A
Type or bisphenol F type has a good affinity for carbon fibers composed of fine graphite crystals by having a π-conjugated system, so it exhibits excellent interfacial adhesion Is preferred.

In the compound having a functional group represented by the general formula (1) and an epoxy group represented by the general formula (2) in the molecule, the number of the functional groups is determined by the formula (4)
It may be one by one as in the compounds shown by (9), or may be plural. When a plurality of functional groups are present, the structures of these functional groups may all be different, or the same may be present. In a sizing agent for carbon fiber composed of such a compound as a main component, as the main component,
One of the compounds may be used alone, or a plurality of compounds may be used in combination as a mixture. The sizing agent may contain the above-described compound as a main component.
It suffices if it is at least weight%. As other components used in combination with this main component, for example, various epoxy resins, urethane resins, polyester resins, and the like can be used.

The sizing agent for carbon fibers mainly comprising the compound having the functional group represented by the general formula (1) and the epoxy group represented by the general formula (2) has the above two types of functional groups. Since each has at least one, also for carbon fiber, acrylic resin,
It also has excellent affinity for matrix resins such as radically polymerizable resins such as unsaturated polyester resins and vinyl ester resins. Therefore, the carbon fiber treated with the sizing agent exhibits good wettability to the matrix resin, and as a result, can be a carbon fiber from which a composite material having excellent mechanical properties can be obtained.

When the sizing agent for carbon fibers is applied to carbon fibers, it is appropriate to disperse the sizing agent in water or an organic solvent such as acetone and use it as a sizing agent solution. In particular, the sizing agent solution is preferably a sizing agent solution in which a sizing agent for carbon fibers is dispersed in an aqueous solution. For sizing agent solutions,
It is preferable to use a water-emulsion type as compared with an organic solvent solution such as acetone or the like, because it is industrially superior and also in terms of safety. When preparing a sizing agent solution obtained by dispersing the carbon fiber sizing agent in an aqueous solution, it is preferable to use a surfactant to enhance dispersibility, enhance solution stability, and improve handleability. Is preferable. As the surfactant used here, any of nonionic, cationic and anionic surfactants can be used. In particular, a nonionic surfactant has excellent storage stability in a prepreg state when forming a carbon fiber reinforced resin composition using a sizing agent solution using the same, and
It is preferable because it does not have a salt which causes trouble when it is combined with a thermoplastic resin or the like, and is easy to handle.

The compounding ratio of the sizing agent for carbon fibers and the surfactant is as follows: sizing agent / surfactant = 95 by weight.
/ 5 to 70/30, preferably a sizing agent /
Surfactant = 85/15 to 75/25. In this range, the sizing agent solution obtained by using the sizing agent has good stability, and is preferable because it does not adversely affect the effect of the sizing agent. When the compounding ratio of the surfactant is less than the above range at this compounding ratio, the stability of the sizing agent solution obtained by using the same decreases. On the other hand, if it exceeds the above range, when treating the carbon fiber with the sizing agent solution obtained using the same, there occurs a disadvantage that the surface of the carbon fiber is coated with a surfactant, and the sizing agent is effectively used. Since it cannot act, it has an adverse effect on the effect of improving the interfacial adhesion of carbon fibers. In addition, by blending a leveling agent with such a sizing agent solution, a carbon fiber having improved scratch resistance can be obtained.

The surface of the carbon fiber according to the present invention is treated with the sizing agent for carbon fiber or the sizing agent solution. The carbon fiber treated using such a sizing agent solution may be composed of any raw material such as pitch, rayon or polyacrylonitrile. The type may be any type such as a high-strength type (low-elastic modulus carbon fiber), a medium-high-elasticity carbon fiber, and an ultra-high-elasticity carbon fiber. Furthermore, the form may be any form such as a long fiber, a short fiber or a sheet-like form such as a woven fabric, a knitted fabric, or a nonwoven fabric, and is not particularly limited.

The amount of the carbon fiber sizing agent to be attached to the carbon fibers is 0.1% by weight to 5.0% by weight, preferably 0.2% by weight to the carbon fibers.
3.0% by weight. If the amount of adhesion is within this range, the effect of the sizing agent can be sufficiently imparted to the carbon fibers. If the amount of the carbon fiber sizing agent is less than 0.1% by weight, sufficient convergence and abrasion resistance of the carbon fiber cannot be obtained. In addition, since the affinity with the resin and the interfacial adhesive strength are insufficient, there arises a problem that a carbon fiber reinforced resin using the resin cannot obtain good mechanical properties. On the other hand, when the content exceeds 5.0% by weight, the convergence is too strong, so that the carbon fiber bundle spreadability deteriorates and impregnation of the resin inside the bundle is inhibited when it is combined with the matrix resin. This causes inconveniences, for example.

The amount of the sizing agent for carbon fibers adhered to the carbon fibers is adjusted by a method such as adjusting the concentration of the sizing agent solution or adjusting the passage step using a squeezing controller or the like. The carbon fibers to which the sizing agent for carbon fibers of the present invention adheres are less likely to generate fluff and the like due to mechanical friction and the like, and are excellent in affinity and adhesion to a matrix resin.

In order to attach the carbon fiber sizing agent to the carbon fiber, a method generally used in industry such as a roller dipping method or a roller contact method can be applied. The carbon fiber to which the sizing agent for carbon fiber is attached is subsequently dried, and after removal of water or an organic solvent contained in the sizing agent solution attached at the same time as attaching the sizing agent, And carbon fiber reinforced resin compositions. The drying process here
It is performed by a method using hot air, a hot plate, a roller, various infrared heaters, or the like as a heat medium.

The carbon fiber sheet according to the present invention is characterized by using carbon fibers treated with the above-mentioned sizing agent, and includes woven fabric, unidirectionally arranged sheet, non-woven fabric, mat and the like. Are combined. Examples of the sheet-like material include those in which carbon fibers are aligned in one direction. As such a sheet-like material, one obtained by simply arranging carbon fibers in one direction at regular intervals, or arranging wefts in the width direction, or after arranging in the horizontal direction using heat-fusible fibers as the wefts Examples include those fixed by heat fusion, and those formed into a sheet by means of arranging a heat-fusible web or net on the sheet surface. In particular, in the present invention, the sheet-like material in which the carbon fibers are arranged in one direction is provided on at least one surface of the carbon fiber sheet-like material (a) aligned in one direction in a direction perpendicular to the carbon fibers. (B) at least one surface of a sheet of carbon fibers aligned in one direction, made of a thermoplastic resin or a thermoplastic resin; Those obtained by heat-sealing a fusible fiber cloth such as a coated net-like support or a web-like support are preferably used. The sheet-like material of (a)
The carbon fiber is manufactured by aligning the carbon fibers in one direction to form a sheet, arranging heat-fusible fibers in the width direction of the reinforcing fibers, heating and heat-fusing the carbon fibers. Placement interval is
3 to 150 mm is preferable, and 3 to 15 m is more preferable.
m. If the spacing is smaller than this, the handleability of the sheet is good, but the restraint of the carbon fiber tends to be too strong and the impregnation of the resin tends to decrease. It is not preferable because the handling property as a product tends to decrease. The sheet material of (b) was formed into a sheet shape in which carbon fibers were aligned in one direction, and at least one surface thereof was coated with a thermoplastic resin or a thermoplastic resin which melts at a temperature of room temperature or higher and exhibits adhesiveness. It is manufactured by heat-sealing a heat-fusible fiber cloth such as a net-like support and a web-like support. The opening of the net of the net-like support is preferably wider from the viewpoint of resin impregnation, and preferably has a side of a polygon of 1 mm or more and an opening area of 10 mm ² or more. More preferably, one side is 2.5 mm or more and the opening area is 15 mm ² or more. On the other hand, from the viewpoint of prevention of fraying of the carbon fiber and handleability at the time of cutting, it is preferable that the aperture is small, and one side is 20 m.
m and the opening area is preferably 500 mm ² or less. The web-like support is a sheet-like material in which short fibers or long fibers are entangled. The basis weight of the net-like or web-like support is from the viewpoint of the mechanical properties of the obtained molded article, particularly from the viewpoint of the retention of interlayer shear strength and the resin impregnation of the sheet-like article.
It is preferably 20 g / m ² or less.

The carbon fiber sheet woven fabric according to the present invention is characterized in that the carbon fibers treated with a sizing agent are used as woven yarn. The weave structure is not particularly limited, and may be a plain weave, a twill weave, a satin weave, or a structure in which these original structures are changed. Further, both the weft and the warp may be the above-mentioned carbon fiber, or may be a mixed weave with another carbon fiber or a fiber other than the carbon fiber. Examples of fibers other than carbon fibers include inorganic fibers such as glass fibers, tyrano fibers, and SiC fibers, and organic fibers such as aramid, polyester, PP, nylon, acrylic, polyimide, and vinylon.
In order to improve the handleability and the resin impregnation property, a carbon fiber sheet-like woven fabric using the above-mentioned carbon fiber as a warp and a fiber having a lower tensile modulus than the warp as a weft is desirable. When the tensile modulus of the fiber used as the weft is high, the warp tends to meander in the longitudinal direction, and does not sufficiently exhibit strength as a reinforcing sheet.

Further, a composite fiber composed of two or more kinds may be used. Particularly, a composite system comprising two kinds of fibers having a difference in melting point of 50 ° C. or more is particularly excellent. The high melting point fiber functions as the original weft, while the low melting point fiber integrates the warp and the weft after weaving to provide excellent handling properties. From the viewpoint of strength development as a reinforcing sheet, it is preferable that the latitude line is thinner, and 1 m
It is desirable that the weight per unit is 0.1 g or less. The weft interval is preferably 3 to 15 mm. If the interval is smaller than 3 mm, meandering in the longitudinal direction of the warp cannot be ignored, causing a decrease in strength development. On the other hand, if the interval is 15
When the width is larger than mm, the handleability as a sheet-like material is undesirably reduced. The more preferable interval between the latitude lines is 4 to
10 mm. The carbon fiber sheet-like woven fabric of the present invention can also be used for reinforcing sheet materials such as bridges, bridge piers, and building columns.

The carbon fiber reinforced resin composition according to the present invention comprises:
The carbon fiber treated with a sizing agent is used. That is, the above-mentioned carbon fiber becomes a reinforcing fiber, and is compounded with a matrix resin to form a unidirectional prepreg, a cross prepreg, a tow prep, a short fiber reinforced resin impregnated sheet, a short fiber mat reinforced resin impregnated sheet, and the like. It becomes a composition. The matrix resin is not particularly limited, but, for example, an acrylic resin, a vinyl polyester resin, an unsaturated polyester resin or the like, which is a radical polymerization resin, is used. Further, a thermoplastic acrylic resin or the like may be used. Further, a commonly used epoxy resin or the like may be used. In order to produce a carbon fiber reinforced resin composition using such carbon fibers treated with the sizing agent, a generally used method can be employed, for example, a hot melt method, a solvent method, It is performed by a method such as a syrup method or a thickening resin method used for SMC or the like. In the production, carbon fibers treated with the sizing agent are used to impregnate with a matrix resin.

In such a carbon fiber reinforced resin,
Because carbon fiber treated with sizing agent is used,
As the matrix resin, a radical polymerizable resin such as an acrylic resin, an unsaturated polyester resin, and a vinyl ester resin can be used. The matrix resin is represented by the general formula (2) of the compound that is a main component of the sizing agent. Since the epoxy group adheres strongly to the carbon fiber and the functional group represented by the general formula (1) to the matrix resin, the interfacial adhesion between the carbon fiber and the matrix resin is strong,
It shows good mechanical properties. Further, for example, when used as a reinforcing sheet material such as a concrete reinforcing material for civil engineering, a carbon fiber reinforced composite material is used by being wrapped around a concrete column or the like. It is required that the peel strength of the overlapped portion of the above is equal to or higher than the tensile strength of the other non-overlaid portion. If the composite material is formed using the carbon fiber reinforced resin composition of the present invention, the strength of such a superposed portion is high, and it is particularly useful as a reinforcing sheet material.

[0025]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. [Example 1] An acrylonitrile copolymer consisting of 97% by weight of acrylonitrile and 3% by weight of methacrylic acid was dissolved in dimethylformamide (DMF) and discharged from a spinning nozzle. Stretch,
Subsequently, the fiber was washed with boiling water and dried to produce a single fiber denier 0.7 precursor fiber. Next, this precursor fiber was flame-resistant at 200 ° C. to 300 ° C. in air to obtain a flame-resistant fiber, and then carbonized at a maximum temperature of 1400 ° C. in nitrogen gas to obtain a carbon fiber. The carbon fiber thus produced was subjected to surface oxidation treatment electrochemically to obtain a carbon fiber bundle.

The carbon fiber bundle was dipped in a sizing agent solution with a roller and dried with hot air to obtain a sizing agent-adhered yarn. The amount of the sizing agent attached to the carbon fiber bundle is 1.5
0% by weight. As the sizing agent solution, a solution prepared by mixing a compound represented by the general formula (4) with 20% by weight of a nonionic surfactant and preparing a 2% by weight aqueous emulsion solution was used. Then, the obtained sizing agent-attached yarn was produced to produce a sheet-like woven cloth which is a plain woven cloth having a basis weight of 200 g / m ² .
In addition, methacrylic syrup (methyl acrylate prepolymer solution (“Bead Resin BR-73” manufactured by Mitsubishi Rayon Co., Ltd., 20 parts by weight) and methyl methacrylate
Parts by weight) and 4 parts by weight of a curing agent (50% diluted benzoyl peroxide (“Kadox B-CH50” manufactured by Kazaku Co., Ltd.)) with respect to 100 parts by weight.
A matrix resin was prepared by mixing 1 part by weight of a curing accelerator (dimethyl-p-toluidine). The matrix resin is impregnated with the produced sheet-like woven fabric to obtain a carbon fiber reinforced resin composition having a fiber volume content of VF of 40%, which is allowed to stand at room temperature for 25 minutes between 0.05 mm-thick polyester films. This was placed and cured to obtain a sheet-like composite material.

The composite material was subjected to a bending test, cross-section observation, and further, observation of a fractured cross section by a scanning electron microscope (hereinafter abbreviated as “SEM observation”). In the bending test, the bending strength was measured by a method according to JIS K7074. As a result, the bending strength was 750 MPa. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 2 Carbon fibers were prepared in the same manner as in Example 1 except that the compound of the sizing agent in Example 1 was changed from the compound of the general formula (4) to the compound of the general formula (5). Was manufactured to produce a sheet-like woven fabric or a carbon fiber-reinforced resin composition to obtain a sheet-like composite material. Then, similarly to the first embodiment, the bending test, the observation of the cross section,
Further, SEM observation of the fractured cross section was performed. As a result, the bending strength was 650 MPa. Also, no voids and unimpregnated portions were observed in the cross section. In addition, SEM
Observation confirmed the cohesive failure mode of the resin.

[Example 3] Carbon fibers were produced in the same manner as in Example 1 except that the main component of the sizing agent in Example 1 was a compound represented by the above general formula (6). Or a carbon fiber reinforced resin composition was produced to obtain a sheet-like composite material. Then, similarly to the first embodiment, the bending test, the observation of the cross section, and the SE of the fractured cross section were performed.
M observation was performed. As a result, the bending strength was 600 MPa. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 4 A carbon fiber was produced in the same manner as in Example 1 except that the main component of the sizing agent in Example 1 was a compound represented by the general formula (7), and a sheet-like woven fabric was produced. Or a carbon fiber reinforced resin composition was produced to obtain a sheet-like composite material. Then, similarly to the first embodiment, the bending test, the observation of the cross section, and the SE of the fractured cross section were performed.
M observation was performed. As a result, the bending strength was 730 MPa. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 5 Carbon fibers were produced in the same manner as in Example 1 except that the main component constituting the sizing agent in Example 1 was a compound represented by the general formula (8). A woven fabric or a carbon fiber reinforced resin composition was manufactured to obtain a sheet-like composite material. And Example 1
The bending test, the cross-section observation, and the SEM observation of the fractured cross section were performed in the same manner as described above. As a result, the bending strength is 730MP.
a. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 6 A carbon fiber was produced in the same manner as in Example 1 except that the main component constituting the sizing agent in Example 1 was a compound represented by the general formula (9). A woven fabric or a carbon fiber reinforced resin composition was manufactured to obtain a sheet-like composite material. And Example 1
Bending test, observation of cross section, and S
EM observation was performed. As a result, the bending strength was 650 MPa.
Met. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 7 A pultruded product comprising the sizing agent-attached yarn of Example 1 and a matrix resin was molded to produce a composite material comprising a carbon fiber reinforced resin composition. As the matrix resin, a vinyl ester resin ("Delalux Light 3505" manufactured by Dainippon Ink and Chemicals, Inc.) was used. And for that composite,
A tensile test, cross-sectional observation, and SEM observation of the fractured cross section were performed. As a result, the tensile strength was 1500 MPa. Also, no voids and unimpregnated portions were observed in the cross section. Furthermore, the cohesive failure mode of the resin was confirmed from SEM observation.

Example 8 A unidirectional prepreg comprising the sizing agent-attached yarn of Example 1 and a matrix resin was produced, and the prepreg was laminated and cured to produce a unidirectional composite material. Epoxy resin was used as the matrix resin. A bending test was performed on the composite material in the same manner as in Example 1 above. The interlayer shear strength (ILSS) was measured according to ASTM-D-2344. as a result,
The bending strength in the fiber direction is 1750 MPa, the bending strength in the direction perpendicular to the fiber direction is 110 MPa, and the ILSS is 9
It was 5 MPa.

Example 9 A carbon fiber was added to a sizing agent solution prepared as a 2 wt% aqueous emulsion solution by blending 20% by weight of a nonionic surfactant with the compound represented by the general formula (4). ("Pyrofil TR30X" manufactured by Mitsubishi Rayon Co., Ltd. (tensile strength: 4.9 GPa, tensile modulus: 235 GPa, number of filaments: 12,000)
This) was dipped in a roller and dried with hot air to produce a sizing agent-adhered yarn in which the amount of the sizing agent adhered to the carbon fiber bundle was 1.50% by weight. This carbon fiber is used as a warp yarn at a rate of 10 yarns / inch.
2.5 GPa, melting point 840 ° C) and low-melting point nylon fiber (multifilament, melting point 125 ° C)
03 g / m) at a rate of 6 yarns / inch, and then heated at 180 ° C. to obtain a cord-like carbon fiber woven fabric. The obtained woven fabric was pliable and extremely easy to handle without causing fiber disorder or collapse even when handled roughly.

Further, 70 parts by weight of methyl methacrylate, 2 parts of 1,3-butylene glycol dimethacrylate
Weight part, number average molecular weight having a methacryl group at a terminal is 6
000 n-butyl acrylate macromonomer in 25
1 part by weight of n-paraffin, 1 part by weight of γ-methacryloxypropyltrimethoxysilane and 1 part by weight of N, N-dimethyl-p-toluidine. Thus, a reactive mixture was obtained. 2 parts by weight of benzoyl peroxide was added to and mixed with 100 parts by weight of the obtained reactive mixture, and impregnated into the cord fabric to produce a carbon fiber reinforced resin composition. Then, a composite material was obtained. A tensile test piece having a total length of 250 mm shown in FIG. 1 was cut out from the obtained composite material, and the tensile strength was measured at room temperature. Fiber content 100
The tensile strength in terms of% (divided by the theoretical thickness of the fabric) was 4300 MPa.

Similarly, 2 parts by weight of benzoyl peroxide was added to and mixed with 100 parts by weight of the above reactive mixture, and a carbon fiber reinforced resin composition was manufactured using the above-mentioned cord-like woven fabric. As shown in FIG. 2, the sheet-like material was cut out and, as shown in FIG. 2, overlapped so as to form a joint overlapping portion 10 of 100 mm, and allowed to stand at room temperature for 1 hour to be integrally cured to obtain a joint tensile strength test piece. It was fabricated and joint tensile strength was measured at room temperature. The joint tensile strength (converted to the theoretical thickness of the fabric) converted to a fiber content of 100% is 4
It was 350 MPa, which was almost equivalent to the tensile strength without the joint overlap. The rupture was a mixture of the rupture at the joint overlap and the tensile rupture of the base material, and was suitable for a concrete reinforcing material or the like.

Example 10 A room-temperature-curable epoxy resin containing a liquid bisphenol A type epoxy resin as a main component and an aromatic polyamine-modified product as a curing agent was prepared. The cord-like carbon fiber woven fabric used in Example 9 was impregnated with the room temperature-curable ethoxy resin, and allowed to stand at room temperature for 7 days to be cured. The tensile test piece shown in FIG. 1 was prepared from the obtained composite material, and the tensile strength was measured at room temperature. Fiber content 100%
The tensile strength (calculated by the theoretical thickness of the woven fabric) was 4250 MPa. Similarly, a joint tensile strength test piece shown in FIG. 2 was prepared from a composite material having a joint overlapping portion of 100 mm, and the joint tensile strength was measured at room temperature.
The joint tensile strength (calculated by the theoretical thickness of the woven fabric) converted to a fiber content of 100% was 4300 MPa, which was almost equal to the tensile strength without a joint overlap portion. The break was a tensile break of the base material.

[Example 11] A carbon fiber having a sizing agent-attached yarn similar to that of Example 9 ("Pyrofil TR30")
X "(tensile strength 4.9 GPa, tensile modulus 235 GP
a, number of filaments: 12,000) (manufactured by Mitsubishi Rayon Co., Ltd.) with a width of 300 mm and a width of 2.5 mm and a width of 300 mm in one direction using an eye plate and a comb, and glass fibers (tensile elastic modulus of 72. 5GPa, melting point 840 ° C) and low melting point nylon fiber (multifilament, melting point 125 ° C) interlaced yarn (0.03g / m) at 25mm interval per one side (12.5mm interval as a sheet) ) And heat-sealed at 180 ° C. by a hot press to obtain a carbon fiber sheet. The obtained carbon fiber sheet-like material was extremely easy to handle, even if it was supple and somewhat violently handled, without causing fiber disorder or collapse. Reactive mixture 10 as described in Example 9
With respect to 0 parts by weight, 2 parts by weight of benzoyl peroxide was added and mixed, impregnated into the carbon fiber sheet material, and left standing at room temperature for 1 hour to cure to obtain a composite material. The resin impregnating property of the carbon fiber sheet was excellent.

In the same manner as described above, the tensile test piece shown in FIG. 1 and the joint tensile strength test piece shown in FIG. 2 were prepared, and the tensile strength and the joint tensile strength were measured at room temperature. Tensile strength (converted to the theoretical thickness of the fabric) converted to a fiber content of 100% is 4
It was 350 MPa. Joint tensile strength is 4300MPa
Which was almost equal to the tensile strength without the overlapping portion of the joint. The fracture was a mixture of the joint overlap fracture and the base metal tensile fracture.

Example 12 The carbon fiber sheet of Example 11 was impregnated with the room-temperature-curable epoxy resin of Example 10 and allowed to stand at room temperature for 7 days to cure. Impregnation of the carbon fiber sheet with the resin was very easy. As described above, a tensile test piece (FIG. 1) and a joint tensile strength test piece (FIG. 2)
Was prepared and evaluated at room temperature. The tensile strength (converted to the theoretical thickness of the fabric) converted to a fiber content of 100% is 44.
It was 50 MPa. The joint tensile strength is 4350MP
a, which was almost equal to the tensile strength without the joint overlap. The break was a tensile break of the base material.

Example 13 The same carbon fiber as the sizing agent-attached yarn as in Example 9 ("Pyrofil TR30") was used.
X "(tensile strength 4.9 GPa, tensile modulus 235 GP
a, number of filaments: 12,000) (manufactured by Mitsubishi Rayon Co., Ltd.) with a width of 300 mm and a width of 300 mm in one direction using an eye plate and a comb, and a heat-fusible nonwoven fabric (Daicel Chemical Co., Ltd.) "Diamid Span" (weight 13
g / m ² )), at a temperature of 130 ° C. and a pressure of 0.1 MPa.
Was passed through the heating roller set for 4 seconds to obtain a carbon fiber sheet. The obtained carbon fiber sheet-like material was extremely easy to handle, even if it was supple and somewhat violently handled, without causing fiber disorder or collapse. As in Example 9, 2 parts by weight of benzoyl peroxide was added to and mixed with 100 parts by weight of the reactive mixture, impregnated into the carbon fiber sheet, left to stand at room temperature for 1 hour, and cured to obtain a composite material. I got The resin impregnating property of the carbon fiber sheet was excellent.

Similarly, a tensile test piece (FIG. 1) and a joint tensile strength test piece (FIG. 2) were prepared and evaluated at room temperature. The tensile strength (converted to the theoretical thickness of the fabric) converted to a fiber content of 100% was 4,300 MPa. The joint tensile strength was 4200 MPa, which was almost equal to the tensile strength without a joint overlapping portion. The fracture was a mixture of the joint overlap fracture and the base metal tensile fracture.

Example 14 The carbon fiber sheet of Example 13 was impregnated with the room-temperature-curable epoxy resin of Example 10, allowed to stand at room temperature for 7 days, and cured to obtain a composite material. Impregnation of the carbon fiber sheet with the resin was very easy. Similarly to the above, a tensile test piece (FIG. 1) and a joint tensile strength test piece (FIG. 2) were prepared and evaluated at room temperature. The tensile strength (converted to the theoretical thickness of the fabric) converted to a fiber content of 100% was 4350 MPa. Further, the joint tensile strength was 4300 MPa, which was almost equal to the tensile strength without a joint overlapping portion. The break was a tensile break of the base material.

Comparative Example 1 The procedure of Example 1 was repeated except that the main component constituting the sizing agent was a commercially available bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell). A sizing agent-attached yarn was manufactured to make a plain woven cloth, and a carbon fiber reinforced resin composition was manufactured. A bending test, cross-section observation, and SEM observation of a fractured cross section of the composite material made of the carbon fiber reinforced resin composition were performed in the same manner as in Example 1 above. As a result, the bending strength was 300 MPa. In addition, voids and unimpregnated portions were confirmed in the cross section. Furthermore, the SEM observation clearly confirmed the separation of the interface between the carbon fiber and the resin.

Comparative Example 2 A sizing agent-attached yarn was produced in the same manner as in Example 1 except that the main component constituting the sizing agent in Example 1 was a compound represented by the following general formula (10). The carbon fiber reinforced resin composition was manufactured. A bending test, cross-section observation, and SEM observation of a fractured cross section of the composite material made of the carbon fiber reinforced resin composition were performed in the same manner as in Example 1 above. As a result, the bending strength was 450 MPa. Also, no voids and unimpregnated portions were observed in the cross section. However, the SEM observation clearly confirmed the separation of the interface between the carbon fiber and the resin.

Embedded image

Comparative Example 3 A pultruded product comprising the sizing agent-attached yarn of Comparative Example 1 and a matrix resin was molded to produce a carbon fiber reinforced resin composition. The same matrix resin as that used in Example 7 was used. For the composite material comprising the carbon fiber reinforced resin composition, a tensile test, observation of a cross section, and SEM of a fractured cross section
Observations were made. As a result, the tensile strength was 1200 MPa. In addition, it was confirmed that voids and unimpregnated portions were partially present in the cross section. Furthermore, the SEM observation clearly confirmed the separation of the interface between the carbon fiber and the resin.

COMPARATIVE EXAMPLE 4 The same components as in Example 1 were used as the main components of the sizing agent, and the amount of the sizing agent attached to the carbon fiber bundle was 0.05% by weight. A sizing agent-attached yarn was manufactured to make a plain woven cloth, and a carbon fiber reinforced resin composition was manufactured. A bending test, cross-section observation, and SEM observation of a fractured cross section of the composite material made of the carbon fiber reinforced resin composition were performed in the same manner as in Example 1 above. as a result,
The bending strength was 350 MPa. In addition, it was confirmed that voids and unimpregnated portions were partially present in the cross section. Furthermore, the SEM observation clearly confirmed the separation of the interface between the carbon fiber and the resin.

Comparative Example 5 A sizing agent-adhered yarn was produced by using the same main component as the sizing agent in the same compound as in Example 1 and setting the amount of the sizing agent to the carbon fiber bundle to 6.00% by weight. A plain weave cloth was used to produce a carbon fiber reinforced resin composition. The composite material made of the carbon fiber reinforced resin composition was subjected to a bending test, observation of a cross section, and SE of a broken cross section in the same manner as in Example 1 above.
M observation was performed. As a result, the bending strength was 350 MPa. Further, it was confirmed that voids and unimpregnated portions were partially present in the cross section, and that the resin was not sufficiently impregnated in the carbon fiber bundle. On the other hand, from the SEM observation, the cohesive failure mode of the resin was observed, and it was confirmed that the adhesiveness was sufficient.

Comparative Example 6 A sizing agent was prepared in the same manner as in Example 9 except that the main component constituting the sizing agent was a commercially available bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell). The attached yarn was manufactured to obtain a woven carbon fiber woven fabric or a composite material. A tensile strength test and a joint tensile strength test were performed in the same manner as in Example 9. As a result, the tensile strength was 4300 MPa,
The joint tensile strength became a very small value at 3300 MPa. All fractures of the joint tensile strength test pieces were peeling of the joint overlapping portion.

Comparative Example 7 The procedure of Example 9 was repeated except that the main component constituting the sizing agent was a commercially available bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell). A cordless carbon fiber woven fabric was manufactured, a composite material was manufactured in the same manner as in Example 10, and a tensile strength test and a joint tensile strength test were performed. As a result, the tensile strength was 3700MPa, and the joint tensile strength was 3800MPa.
The value of a was considerably small. All fractures of the joint tensile strength test pieces were tensile fractures of the base material.

Comparative Example 8 The procedure of Example 11 was repeated, except that the main component constituting the sizing agent was a commercially available bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell). A composite material was manufactured, and a tensile strength test and a joint tensile strength test were performed. As a result, the tensile strength was 4,200 MPa, but the joint tensile strength was 3,400 MPa, a considerably small value. All fractures of the joint tensile strength test pieces were peeling of the joint overlapping portion.

Comparative Example 9 The procedure of Example 13 was repeated except that the main component constituting the sizing agent was a commercially available bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell). A composite material was manufactured, and a tensile strength test and a joint tensile strength test were performed. As a result, the tensile strength was 4300 MPa, but the joint tensile strength was a considerably small value of 3200 MPa. All fractures of the joint tensile strength test pieces were peeling of the joint overlapping portion.

[Conventional Example] A unidirectional prepreg made of the sizing agent-attached yarn of Comparative Example 1 and a matrix resin was manufactured, and the prepreg was laminated and cured to produce a unidirectional composite material. A composition was prepared. Epoxy resin was used as the matrix resin. A bending test was performed on the carbon fiber reinforced resin composition in the same manner as in Example 1 above. In addition, ILSS was measured. Since a sizing agent-attached yarn suitable for epoxy resin is used, the bending strength in the fiber direction is 17
00 MPa, bending strength in the direction perpendicular to the fiber direction is 12
It was 0 MPa and ILSS 90 MPa.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

[0058]

[Table 4]

From the above results, in the examples of the present invention, sufficient strength was obtained, no voids and unimpregnated portions were confirmed at all, and the cohesive failure mode of the resin could be confirmed from SEM observation. Thus, it was confirmed that it was superior to the comparative example. In addition, it was confirmed that even when an epoxy resin was used as the matrix resin, the epoxy resin could be used as well as the conventional example.

[0060]

As described above, according to the present invention,
It has excellent affinity not only for epoxy resins but also for matrix resins such as acrylic resins, unsaturated polyester resins, vinyl ester resins, and other radical polymerization resins, and wets both carbon fibers and matrix resins. It is possible to improve the performance and obtain a stable effect. In addition, the sizing agent solution in which the carbon fiber of the present invention is treated is one in which the sizing agent for carbon fiber is dispersed in water. In addition, it can be made excellent in terms of safety.

Furthermore, the carbon fiber sheet and the carbon fiber reinforced resin composition of the present invention are obtained by treating the carbon fibers used therein with the sizing agent for carbon fibers of the present invention. Since a strong adhesive force can be obtained at the interface with the matrix resin, it has excellent mechanical properties. In particular, when the compound in the sizing agent has a functional group located at one end of the main chain, the matrix resin and the carbon fiber are more strongly bonded. When the epoxy group is a glycidyl group, more excellent interfacial adhesiveness is exhibited. Also,
The effect of the carbon fiber sizing agent is particularly exhibited when the amount of the carbon fiber sizing agent is 0.1% by weight to 5.0% by weight.

[Brief description of the drawings]

FIG. 1 shows a tensile test piece, where FIG. 1 (a) is a side view and FIG. 1 (b) is a plan view.

FIG. 2 shows a joint tensile strength test piece, and FIG.
2A is a side view, and FIG. 2B is a plan view.

Claims (16)

[Claims] 1. A sizing agent for carbon fibers comprising a compound having a functional group represented by the following general formula (1) and an epoxy group represented by the following general formula (2). Embedded image (In the general formula (1), R is a hydrogen atom or an alkyl group.) 2. It has one functional group represented by the general formula (1) and one epoxy group represented by the general formula (2), and these functional groups are respectively located at one end of the main chain. The sizing agent for carbon fibers according to claim 1, wherein: 3. The sizing agent for carbon fibers according to claim 1, wherein the epoxy group is a glycidyl group represented by the following general formula (3). Embedded image 4. A carbon fiber to which the sizing agent for carbon fiber according to claim 1 is adhered. 5. The method according to claim 1, wherein the amount of the sizing agent for carbon fibers is not more than 0.5.
5. The composition according to claim 4, wherein the content is in the range of 1 to 5% by weight.
The carbon fiber as described. 6. A sizing agent solution for carbon fibers, wherein the sizing agent for carbon fibers according to any one of claims 1 to 3 is dispersed in an aqueous solution. 7. A carbon fiber sheet comprising the carbon fiber according to claim 4. Description: 8. The carbon fiber sheet according to claim 7, wherein the carbon fibers are aligned in one direction. 9. The carbon fiber sheet according to claim 8, wherein at least one surface of the carbon fiber sheet is perpendicular to the carbon fibers aligned in the one direction.
A carbon fiber sheet comprising heat-fusible fibers arranged at predetermined intervals and heat-fused. 10. The carbon fiber sheet according to claim 8, wherein a heat-fusible fiber cloth is heat-sealed to at least one surface thereof. 11. A carbon fiber sheet woven fabric comprising the carbon fiber according to claim 4 as a woven yarn. 12. The carbon fiber sheet-like woven fabric according to claim 11, wherein the carbon fiber is a warp, and the fiber having a lower tensile modulus than the warp is a weft. 13. The weft is a composite yarn comprising two kinds of fibers having a melting point difference of 50 ° C. or more, and the weight per 1 m is 0.1 g or less, and the interval between the wefts in the radial direction is 3 to 15 mm.
The carbon fiber sheet-like woven fabric according to claim 11, wherein the warp and the weft are bonded to each other by the low-melting fiber of the weft. 14. A carbon fiber reinforced resin composition comprising the carbon fiber according to claim 4. 15. The carbon fiber reinforced resin composition according to claim 14, wherein the carbon fibers are aligned in one direction. 16. A carbon fiber reinforced resin composition comprising the carbon fiber sheet woven fabric according to any one of claims 11 to 13.