JP2012219425A - Sizing agent for carbon fiber, carbon fiber bundle and method for producing carbon fiber bundle - Google Patents

Abstract

Disclosed is a carbon fiber sizing agent that is excellent in process stability during sizing treatment of carbon fiber and that is used for a composite material of a thermoplastic resin such as polypropylene and carbon fiber.
SOLUTION: It contains a copolymerized polyolefin and a glycol ether compound, the solubility of the glycol ether compound in water at 20 ° C. is 0 to 100 g, and the content of the glycol ether compound is It is set as the sizing agent for carbon fibers which is 15-2000 weight part with respect to 100 weight part of solid content of this copolymerization polyolefin.
[Selection figure] None

Description

  The present invention relates to a sizing agent for carbon fiber, a carbon fiber bundle provided with the sizing agent, and a method for producing the carbon fiber bundle. In particular, the present invention relates to a sizing agent for carbon fiber used for a composite material of a thermoplastic resin such as polypropylene and carbon fiber, a carbon fiber bundle provided with the sizing agent, and a method for producing the carbon fiber bundle.

Carbon fiber is a material that has been widely applied as a composite material with a resin in order to increase the strength of the resin and at the same time, the resin can buffer the brittle fracture of the carbon fiber. When compounding, the advantage is increased by having a strong adhesion interface between the carbon fiber and the resin. On the other hand, if the carbon fiber is used as it is, since the carbon fiber is composed of a large number of ultrafine filaments, the elongation is small and fluff is likely to occur due to mechanical friction.
In order to improve these problems, a sizing agent is added to the carbon fiber for the purpose of improving the adhesiveness with the matrix resin at the time of compounding with the resin and improving the convergence and handling properties of the carbon fiber. It is common.

Resins used for compounding with carbon fibers include thermosetting resins and thermoplastic resins. Carbon fiber composite materials that have been widely applied so far are those using epoxy resins of thermosetting resins. there were.
For example, Patent Document 1 proposes a sizing agent containing bisphenol A type epoxy resin that is liquid at room temperature, bisphenol A type epoxy resin that is solid at room temperature, unsaturated polyester resin, and stearic acid as essential components. However, these are sizing agents for thermosetting resins, and the thermosetting resin itself requires a long heating time until it is cured, and once cured, there is a problem from the viewpoint of recycling and processing.

On the other hand, the use of a thermoplastic resin as the matrix resin of the carbon fiber composite material solves the above-mentioned heating time and processing problems, but the carbon fiber coated with a sizing agent developed for thermosetting resins is heated. Even if it is combined with a plastic resin, the adhesion between the carbon fiber and the thermoplastic resin becomes insufficient, and the resulting carbon fiber composite material cannot provide sufficient strength.
Therefore, many proposals have been made so far as a sizing agent for a carbon fiber composite material using a thermoplastic resin. For example, Patent Document 2 proposes a carbon fiber coated with polyurethane and a carbon fiber reinforced thermoplastic resin composition composed of the carbon fiber and a thermoplastic resin. According to this proposal, it is disclosed that the handleability of carbon fibers can be improved and the mechanical properties of the carbon fiber reinforced thermoplastic resin composition can be improved. However, the thermoplastic resin used here is a highly polar resin such as polyamide or polycarbonate, and the carbon fiber to which the sizing agent disclosed in these prior arts is added is a low-polarity thermoplastic resin such as polypropylene. Even if they are combined, the resulting carbon fiber composite material does not have sufficient strength.

Patent Document 3 discloses a polypropylene, which is a thermoplastic resin that contributes to weight reduction at low cost by using a copolymerized polyolefin containing an acid and / or an acid anhydride as a copolymerization component as a sizing agent for carbon fiber. It is disclosed that the adhesion of the resin is improved.
However, when a copolymerized polyolefin or an emulsion or solution containing the copolymerized polyolefin as a main component is applied to the carbon fiber as a sizing agent, the sizing agent tends to adhere to various devices used for sizing treatment, and the process is inconvenient. It becomes stable.

JP-A-7-197381 JP 58-126375 A JP 2006-124847 A

  The present invention relates to a sizing agent for carbon fibers used in a composite material of a thermoplastic resin such as polypropylene and carbon fibers, which has excellent process stability during sizing treatment on carbon fibers, and carbon provided with the sizing agent. The object is to provide a fiber bundle.

  The present inventors have found that the title problem can be solved by adding a glycol ether compound to the copolymerized polyolefin. That is, the present invention contains a copolymerized polyolefin and a glycol ether compound, the solubility of the glycol ether compound in water at 20 ° C. is 0 to 100 g, and the content of the glycol ether compound Provides a sizing agent for carbon fiber in an amount of 15 to 2000 parts by weight based on 100 parts by weight of the solid content of the copolymerized polyolefin.

The glycol ether compound used in the present invention is preferably a propylene glycol glycol ether compound.
Moreover, it is preferable that the copolymerization polyolefin used by this invention contains an aromatic vinyl compound and an acid and / or an acid anhydride as a copolymerization component.
Furthermore, in this invention, it is preferable that the solubility to the water at 20 degreeC of the said glycol ether compound and content of the glycol ether type compound with respect to 100 weight part of solid content of copolymerization polyolefin satisfy the following formula.
A ≧ 11.167 × B + 22.22
(A is the content / part by weight of the glycol ether compound relative to 100 parts by weight of the solid content of the copolymerized polyolefin, and B is the solubility / g of the glycol ether compound in water at 20 ° C.).

This invention provides the carbon fiber bundle formed by providing the above-mentioned carbon fiber sizing agent to the carbon fiber surface.
Moreover, this invention provides the manufacturing method of the carbon fiber bundle containing the process of providing the above-mentioned sizing agent for carbon fibers to the carbon fiber surface, and the process of drying the sized carbon fiber.

  ADVANTAGE OF THE INVENTION According to this invention, the sizing agent for carbon fibers for thermoplastic resins, such as a polypropylene excellent in process stability in the case of the sizing process to carbon fiber, can be provided. By using the sizing agent of this invention, the carbon fiber bundle used for the composite material of thermoplastic resins, such as a polypropylene, and carbon fiber can be obtained preferably.

It is the figure which plotted the minimum addition amount of the glycol ether type compound required for (circle) evaluation with respect to the solubility to 20 degreeC water solubility of each glycol ether compound in the Example of this invention.

Hereinafter, embodiments of the present invention will be sequentially described.
<Copolymerized polyolefin>
The copolymerized polyolefin constituting the carbon fiber sizing agent of the present invention is specifically composed mainly of an aliphatic polyolefin and a component copolymerized therewith. The type of the aliphatic polyolefin is not particularly limited, and examples include non-modified polyolefin, chlorinated polyolefin, acid-modified polyolefin, and amino-modified polyolefin. Moreover, the copolymerization component with polyolefin is not specifically limited, What is necessary is just to be copolymerizable with polyolefin, such as an aromatic vinyl compound, an acrylate-type compound, an acid, and / or an acid anhydride. Specifically, styrene, methylstyrene, vinyl chloride, vinyl acetate, acrylic acid, methacrylic acid, and the like. In particular, a copolymerized polyolefin containing an aromatic vinyl compound and an acid and / or an acid anhydride as a copolymerization component is preferable because it exhibits high adhesive strength when a composite material of carbon fiber and polypropylene is used.

  That is, as the copolymer polyolefin, a copolymer polyolefin containing an aromatic vinyl compound and an acid and / or an acid anhydride as a copolymer component is preferable. As the copolymerized polyolefin containing an aromatic vinyl compound and an acid and / or acid anhydride as a copolymerization component, propylene-aromatic vinyl compound-acid and / or acid anhydride copolymer, propylene-α-olefin- Aromatic vinyl compound-acid and / or acid anhydride copolymer, ethylene-aromatic vinyl compound-acid and / or acid anhydride copolymer, ethylene-α-olefin-aromatic vinyl compound-acid and / or acid Anhydride copolymer, 1-butene-aromatic vinyl compound-acid and / or acid anhydride copolymer, and 1-butene-α-olefin-aromatic vinyl compound-acid and / or acid anhydride copolymer It is preferably at least one selected from the group consisting of

  Here, the propylene-α-olefin-aromatic vinyl compound-acid and / or acid anhydride copolymer is mainly composed of propylene and α-olefin, aromatic vinyl compound-acid and / or acid anhydride. Copolymerized. Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene and the like, and α-olefins having 2 or 4 to 20 carbon atoms. Is mentioned.

The aromatic vinyl compound has the general formula ArCH═CH ₂
(Ar: aromatic group having 6 to 15 carbon atoms)
It is preferable to be represented by

  Examples of the aromatic group having 6 to 15 carbon atoms include aryl groups such as phenyl group, naphthyl group, biphenylyl group, and phenanthryl group, alkylaryl groups such as methylphenyl group, dimethylphenyl group, and methylnaphthyl, methoxyphenyl group, Examples thereof include alkoxyaryl groups such as butoxyphenyl groups, silyloxyphenyl groups such as trimethylsilyloxyphenyl groups, and halogenated phenyl groups such as bromophenyl groups, chlorophenyl groups, and fluorophenyl groups. Specific examples of the aromatic vinyl compound include styrenes such as styrene, methylstyrene, methoxystyrene, butoxystyrene, trimethylsiloxystyrene, divinylbenzene, chlorostyrene, vinylnaphthalene, vinylbiphenyl, vinylphenanthrene, and the like. . Of these, styrene, methylstyrene, and vinylnaphthalene are preferable.

  When the copolymerization ratio of the olefin and the aromatic vinyl compound in the copolymerized polyolefin is expressed as a molar ratio, the aromatic vinyl compound is preferably 0.1 to 10 with respect to the olefin 100. When the molar ratio is less than 0.1, the adhesion between the carbon fiber bundle and the polypropylene resin tends to be lowered. On the other hand, when the molar ratio exceeds 10, the polyolefin content in the copolymerized polyolefin is relatively decreased, and the adhesion between the carbon fiber and the polypropylene resin may be lowered. More preferably, the aromatic vinyl compound is 1 to 5 with respect to the olefin 100 in a molar ratio.

  The olefin is preferably a copolymer of propylene and / or propylene and an α-olefin. Here, the copolymerization ratio of propylene and the α-olefin is not particularly limited. Olefin 2 to 200. More preferably, it is α-olefin 10 to 150 with respect to propylene 100. More preferably, it is α-olefin 20-100 with respect to propylene 100. As the content ratio of the propylene component increases, the affinity for a thermoplastic resin substrate such as polypropylene resin tends to increase.

  The acid and / or acid anhydride is preferably at least one selected from the group consisting of carboxylic acids and acid anhydrides thereof. Examples of the carboxylic acid include unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and mesaconic acid. Examples of the acid anhydride include maleic anhydride, itaconic anhydride, and citraconic anhydride. Among these, maleic anhydride and itaconic anhydride are preferable. Specifically, the acid and / or acid anhydride modification is preferably a graft copolymerization of a component having an organic acid group such as a carboxyl machine to a copolymer of an olefin and an aromatic vinyl compound. In particular, it is preferable to graft copolymerize at least one selected from the group consisting of unsaturated dicarboxylic acids and acid anhydrides thereof onto a copolymer of an olefin and an aromatic vinyl compound.

That is, the copolymerized polyolefin in the present invention is a group consisting of an unsaturated dicarboxylic acid and an acid anhydride thereof with respect to a propylene-aromatic vinyl compound copolymer and / or a propylene-α-olefin-aromatic vinyl compound copolymer. A compound obtained by graft copolymerizing at least one selected from the above is particularly preferable.
Furthermore, the copolymerization ratio of the olefin and the acid and / or acid anhydride in the copolymerized polyolefin in this case is preferably 0.01 to 5 in terms of the molar ratio of the acid and / or acid anhydride with respect to the olefin 100. 0.1 to 2 is more preferable.

<Glycol ether compound>
The glycol ether compound constituting the carbon fiber sizing agent of the present invention has a solubility in water at 20 ° C. of 0 to 100 g. Moreover, content of the glycol ether type compound in the sizing agent for carbon fiber of this invention is 15-2000 weight part with respect to 100 weight part of solid content of the copolymerization polyolefin used by this invention. Here, the solubility in water at 20 ° C. in the present invention means an amount (g) that can be dissolved in 100 g of water kept at 20 ° C.

  By adding the above-mentioned glycol ether compound to the copolymerized polyolefin used in the present invention, it can be applied to various apparatuses used in the process of sizing treatment of a carbon fiber such as a bath containing a sizing agent or a roller used for coating. Sticking of the sizing agent is suppressed and process stability is improved.

In the present invention, the glycol ether compound having a lower solubility in water at 20 ° C. tends to have a smaller content of the required glycol ether compound.
The solubility of the glycol ether compound used in water at 20 ° C. is preferably 0 to 30 g. If the solubility of the glycol ether compound in water at 20 ° C. is in a suitable range, the adhesion to a roller or the like can be suppressed with a sufficiently small amount with respect to the copolyester used in the present invention. Moreover, it is preferable that the minimum of content of a glycol ether type compound shall be 25 weight part or more with respect to 100 weight part of solid content of copolymerization polyolefin used by this invention. Moreover, it is preferable that the upper limit of content of a glycol ether type compound shall be 500 weight part or less with respect to 100 weight part of solid content of the copolymerization polyolefin used by this invention. If it is this range, since the performance of a sizing agent is not reduced, it is preferable.

Furthermore, from the results of Examples described later, the solubility of the glycol ether compound in water at 20 ° C. and the content of the glycol ether compound relative to 100 parts by weight of the copolymerized polyolefin satisfy the following formula (1). In the range, it has been found that the fixing of the sizing agent for carbon fiber according to the present invention to various devices is greatly suppressed, and the process stability is remarkably improved.
A ≧ 11.167 × B + 22.22 (1)
(A is the content / part by weight of the glycol ether compound relative to 100 parts by weight of the solid content of the copolymerized polyolefin, and B is the solubility / g of the glycol ether compound in water at 20 ° C.).

  The kind of glycol ether type compound used in the present invention is not particularly limited, and examples thereof include propylene glycol type, ethylene glycol type, dialkyl glycol ether type and the like. Preferably, a propylene glycol glycol ether is used. Specific examples of the propylene glycol-based glycol ether include phenylpropylene glycol, butylpropylene diglycol, butylpropylene glycol, methylpropylene glycol acetate, and dibutyl diglycol. Examples of the ethylene glycol glycol ether include hexyl glycol, 2-ethylhexyl glycol, phenyl glycol, benzyl glycol and the like. Examples of dialkyl glycol glycol ethers include dibutyl diglycol and dimethylpropylene diglycol.

<Method for producing carbon fiber bundle>
The carbon fiber bundle of the present invention contains a copolymerized polyolefin and a glycol ether compound, the solubility of the glycol ether compound in water at 20 ° C. is 0 to 100 parts, and the glycol ether compound The carbon fiber sizing agent having a content of 10 to 2000 parts by weight based on 100 parts by weight of the solid content of the copolymerized polyolefin is applied to the surface of the carbon fiber and then preferably dried. At this time, the application amount of the sizing agent for carbon fiber is not particularly limited, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of carbon fiber.

  In the present invention, the carbon fiber sizing agent can be used in an aqueous emulsion or a solution state using a solvent in which the carbon fiber sizing agent can be dissolved. In the present invention, the carbon fiber sizing agent is used in an aqueous emulsion. Is preferred. In the case of an aqueous emulsion, the amount of water is preferably 2000 to 10,000 parts by weight with respect to 100 parts by weight of the copolymerized polyolefin in the sizing agent for carbon fiber. In this aqueous emulsion, for example, a sizing agent for carbon fiber is dissolved in a solvent such as toluene and xylene, a surfactant is added as necessary to increase dispersibility, a basic substance is added, and water is added little by little. It can preferably be obtained by a phase inversion emulsification method.

  That is, in order to obtain the carbon fiber bundle of the present invention, when the carbon fiber sizing agent is used in an aqueous emulsion, it is preferable to use a surfactant in order to improve dispersibility. There is no restriction | limiting in particular as surfactant, If it is a range which does not impair the objective of this invention, a well-known surfactant can be used. The preferable use amount of the surfactant is 1 to 30 parts by weight with respect to 100 parts by weight of the copolymerized polyolefin in the carbon fiber sizing agent. If it is 1 part by weight or more, the resin dispersion is further improved as compared with the case of less than 1 part by weight, and the tensile shear property with the carbon fiber bundle is further improved. On the other hand, if it exceeds 30 parts by weight, the water resistance of the sizing agent for carbon fibers may deteriorate, and the tensile shear characteristics with the carbon fiber bundle may deteriorate.

  As a method for obtaining a carbon fiber bundle by adhering the carbon fiber sizing agent to the surface of the carbon fiber, a method for adhering the carbon fiber sizing agent in an aqueous emulsion or solution state, that is, as a sizing method, for example, spraying Method, roller dipping method, roller transfer method and the like. Among these sizing methods, a roller dipping method excellent in productivity and uniformity is preferable. When carbon fiber strands are immersed in an aqueous emulsion or solution, opening and squeezing are repeated through an immersion roller provided in the emulsion bath, and the carbon fiber sizing solution is impregnated into the strands. It is essential.

  After the carbon fiber sizing agent according to the present invention is attached to an unsized carbon fiber bundle in the form of an aqueous emulsion or solution, the moisture or solvent is removed by subsequent drying treatment to give the desired carbon fiber sizing agent. Carbon fiber can be obtained. Adjustment of the adhesion amount of the carbon fiber sizing agent to the carbon fiber is performed by adjusting the concentration of the carbon fiber sizing agent, adjusting the squeeze roller, or the like.

For drying the carbon fiber, for example, hot air, a hot plate, a roller, an infrared heater or the like can be used.
The drying treatment is preferably heat treatment, and in addition to removing moisture or solvent by heat treatment, the carbon fiber sizing agent can be uniformly applied to the surface of the carbon fiber.

  In the heat treatment step, the treatment is preferably performed at 80 ° C. to 160 ° C. for 30 seconds or longer. In the case of an aqueous emulsion, specifically, water is removed at 80 ° C., and then the copolymerized polyolefin in the sizing agent for carbon fiber is used. It is preferable to form a uniform film by heat treatment at a temperature exceeding the melting point of, for example, 150 ° C. By performing the heat treatment at a temperature of 80 ° C. to 160 ° C., moisture or solvent can be quickly removed and deterioration of the sizing agent due to thermal deterioration of the copolymerized polyolefin in the sizing agent for carbon fiber can be suppressed.

<Carbon fiber>
As the carbon fiber constituting the carbon fiber bundle of the present invention, any carbon fiber such as polyacrylonitrile (PAN), petroleum / coal pitch, rayon, and lignin can be used. In particular, PAN-based carbon fibers using PAN as a raw material are preferable because they are excellent in productivity and mechanical properties on an industrial scale.
It is preferable to use carbon fibers having an average diameter of 5 to 10 μm. Moreover, it is preferable to use a fiber bundle of 1000 to 50000 short fibers. In order to enhance the adhesion between the carbon fiber and the matrix resin, it is also preferable to use a material in which an oxygen-containing functional group is introduced on the surface of the carbon fiber by a surface treatment.

Examples are shown below, but the present invention is not limited thereto.
[Example 1]
Propylene-1-butene / styrene copolymer (molar ratio of butene to propylene 100 is 30, molar ratio of styrene to propylene 100 is 1) 28 parts by weight, maleic anhydride 40 parts by weight, di-tert-butyl peroxide 5.6 parts by weight and 420 parts by weight of toluene were added to an autoclave equipped with a stirrer, and after substituting with nitrogen for about 5 minutes, the reaction was carried out at 140 ° C. for 5 hours with heating and stirring. After completion of the reaction, the reaction solution was put into a large amount of methyl ethyl ketone to precipitate a crude copolymer polyolefin. The crude copolymerized polyolefin was further washed with methyl ethyl ketone and dried under reduced pressure to obtain a copolymerized polyolefin solid. From the measurement result of the infrared absorption spectrum, the copolymerization ratio of maleic anhydride was 1.1 with respect to propylene 100 in molar ratio. Moreover, the weight average molecular weight by high temperature GPC measurement was 40000.
5, 25, 50, 100, 250, 500, 1000, 2000 parts by weight of phenylpropylene glycol (manufactured by Nippon Emulsifier, CAS770-) with respect to 100 parts by weight of the obtained copolymerized polyolefin and 100 parts by weight of the solid content of the copolymerized polyolefin. 35-4, solubility in water (20 ° C.): 0.2 g) was added with 400 parts by weight of toluene and heated with stirring to uniformly dissolve the copolymer polyolefin. In another container, 8 parts by weight of a polyoxyethylene alkyl ether surfactant (registered trademark “Emulgen 103” manufactured by Kao Corporation) as a surfactant was added to 400 parts by weight of water and dissolved. A toluene solution of a carbon fiber sizing agent and an aqueous surfactant solution were placed in an emulsifier and stirred. Morpholine was added thereto, and toluene and water were distilled under reduced pressure using a rotary evaporator to obtain a pre-emulsion.
The obtained pre-emulsion had an average particle size of 0.7 μm, pH of 8.5, and water was 400 parts by weight with respect to 100 parts by weight of polyolefin.
Water was added to the pre-emulsion so that the amount of water was 4900 parts by weight with respect to 100 parts by weight of the copolymerized polyolefin to obtain a carbon fiber sizing agent aqueous emulsion. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, in the case of adding 25 parts by weight or more of phenylpropylene glycol to 100 parts by weight of the solid content of the copolymerized polyolefin, suppression of fixing of the sizing agent for carbon fiber to the stainless cup was observed, and the carbon fiber on the inner wall of the stainless cup was observed. The film was stable with almost no sizing agent film formed.

[Example 2]
Similarly, the sizing agent aqueous emulsion for carbon fiber, except that the phenylpropylene glycol of Example 1 was changed to butyl propylene diglycol (manufactured by Nippon Emulsifier, CAS 29911-28-2, solubility in water (20 ° C.): 3.0 g). Was prepared. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, when 25 parts by weight or more of butylpropylene diglycol was added to 100 parts by weight of the solid content of the copolymerized polyolefin, suppression of fixing of the sizing agent for carbon fiber to the stainless cup was observed, and carbon on the inner wall of the stainless cup was observed. It was stable with almost no fiber sizing agent film formed.

[Example 3]
Similarly, a sizing agent aqueous emulsion for carbon fiber was used except that phenylpropylene glycol of Example 1 was changed to butyl propylene glycol (manufactured by Nippon Emulsifier, CAS 5131-66-8, solubility in water (20 ° C.): 6.4 g). Prepared. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, when butyl propylene glycol was added in an amount of 25 parts by weight or more with respect to 100 parts by weight of the solid content of the copolymerized polyolefin, the carbon fiber sizing agent was prevented from sticking to the stainless cup, and the carbon fiber on the inner wall of the stainless cup was observed. The film was stable with almost no sizing agent film formed.

[Example 4]
Similarly, the sizing agent aqueous emulsion for carbon fiber, except that the phenylpropylene glycol of Example 1 was changed to methyl propylene glycol acetate (manufactured by Nippon Emulsifier, CAS108-65-6, solubility in water (20 ° C.): 20.5 g). Was prepared. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, in the case of adding 25 parts by weight or more of methylpropylene glycol acetate to 100 parts by weight of the solid content of the copolymerized polyolefin, the carbon fiber sizing agent was prevented from sticking to the stainless steel cup, and the carbon on the inner wall of the stainless steel cup was observed. It was stable with almost no fiber sizing agent film formed.

[Comparative Example 1]
Similarly, a sizing agent aqueous emulsion for carbon fiber was used except that phenylpropylene glycol in Example 1 was methylpropylene triglycol (manufactured by Nippon Emulsifier, CAS 20324-33-8, water solubility (20 ° C.): infinite). Prepared. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, a carbon fiber sizing agent film was formed on the inner wall of any stainless steel cup.

[Comparative Example 2]
A carbon fiber sizing agent aqueous emulsion was similarly prepared except that phenylpropylene glycol in Example 1 was omitted. Each was put into a stainless steel cup and allowed to stand for 6 hours in a natural convection dryer maintained at 40 ° C.
As a result, a carbon fiber sizing agent film was formed on the inner wall of any stainless steel cup.

[Consideration of Examples]
In Table 1, the minimum addition amount of the glycol ether compound required for the evaluation is plotted against the solubility of each glycol ether compound in water at 20 ° C. for the range in which the sticking suppression is greatly suppressed ( FIG. 1). When an expression that satisfies the plot is calculated using the least squares method,
A ≧ 11.167 × B + 22.22
However,
A is the content of glycol ether compound per 100 parts by weight of copolymerized polyolefin / part by weight B is the solubility of water in glycol ether compound at 20 ° C./g

[Reference Example 1]
In the bath of the sizing agent emulsion for carbon fiber of Example 2, unsized carbon fiber strand (manufactured by Toho Tenax Co., Ltd., registered trademark “Tenax STS-24K N00”, diameter 7 μm × 24000 filament, fineness 1.6 g / m, tension A strength of 4000 MPa (408 kgf / mm ² ) and a tensile elastic modulus of 238 GPa (24.3 ton / mm ² ) were continuously immersed, and a sizing agent emulsion for carbon fiber was impregnated between the filaments. This was passed through a dryer at 200 ° C. for about 1 minute to evaporate the water, and then dried and heat treated. When the amount of the copolymerized polyolefin adhered to the obtained carbon fiber bundle was measured, it was 1.2 parts by weight with respect to 100 parts by weight of the carbon fiber bundle.
Two carbon fiber bundles manufactured as described above were prepared, and a polypropylene film (Propylene film manufactured by Tosello Co., CPS # 50) was sandwiched between them and bonded at 230 ° C., and then the length of the bonded portion in accordance with JIS K6850 The tensile shear strength was measured at 7 mm. As a result, high shear strength was obtained as shown in Table 2.

[Reference Comparative Example 1]
A carbon fiber bundle was produced in the same manner as in Reference Example 1 except that the carbon fiber sizing agent emulsion of Comparative Example 2 was used.
Two prepared carbon fiber bundles are prepared. A polypropylene film (Propylene film manufactured by Tosello Co., CPS # 50) is sandwiched between them and bonded at 230 ° C. Then, the bonded portion is pulled with a length of 7 mm in accordance with JIS K6850. Shear strength was measured. As a result, high shear strength was obtained as shown in Table 2.

[Reference Comparative Example 2]
Two carbon fiber bundles obtained from unsized carbon fiber strands (registered trademark “Tenax STS-24K N00” manufactured by Toho Tenax Co., Ltd.) are prepared, and a polypropylene film (Propylene film manufactured by Tosero Co., CPS # 50) is prepared between them. Were bonded at 230 ° C., and the tensile shear strength was measured with a length of 7 mm in accordance with JIS K6850. As a result, as shown in Table 2, the tensile shear strength was lower than that in Reference Example 1 and Reference Comparative Example 1.

[Reference Comparative Example 3]
Carbon fiber strand (registered trademark “Tenax STS-24K F13” manufactured by Toho Tenax Co., Ltd., diameter 7 μm × 24000 filament, fineness 1.6 g / m, tensile strength 4000 MPa (408 kgf / mm) ² ), ^two carbon fiber bundles obtained from a tensile elastic modulus of 238 GPa (24.3 ton / mm ² )) are prepared, and a polypropylene film (a propylene film manufactured by Tosello Co., CPS # 50) is sandwiched between them at 230 ° C. After bonding, the tensile shear strength was measured at a bonded portion length of 7 mm in accordance with JIS K6850. As a result, as shown in Table 2, the tensile shear strength was lower than that in Reference Example 1 and Reference Comparative Example 1.

Claims (6)

  A copolymer polyolefin and a glycol ether compound, the solubility of the glycol ether compound in water at 20 ° C. is 0 to 100 g, and the content of the glycol ether compound is the copolymer polyolefin. The carbon fiber sizing agent which is 15-2000 weight part with respect to 100 weight part of solid content.   The sizing agent for carbon fiber according to claim 1, wherein the glycol ether compound is a propylene glycol glycol ether compound.   The sizing agent for carbon fibers according to claim 1 or 2, wherein the copolymerized polyolefin contains an aromatic vinyl compound and an acid and / or an acid anhydride as a copolymerization component. The solubility of the glycol ether compound in water at 20 ° C. and the content of the glycol ether compound with respect to 100 parts by weight of the solid content of the copolymerized polyolefin satisfy the following formula (1): The sizing agent for carbon fibers according to any one of claims 1 to 3.
A ≧ 11.167 × B + 22.22 (1)
(A is the content / part by weight of the glycol ether compound relative to 100 parts by weight of the solid content of the copolymerized polyolefin, and B is the solubility / g of the glycol ether compound in water at 20 ° C.).   The carbon fiber bundle formed by providing the carbon fiber sizing agent in any one of Claims 1-4 to the carbon fiber surface.   The manufacturing method of the carbon fiber bundle containing the process of providing the sizing agent for carbon fibers in any one of Claims 1-4 to the carbon fiber surface, and the process of drying the carbon fiber which carried out the sizing process.

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