Carbon fiber bundle coated with sizing agent and method for producing the same

Abstract

The present invention provides a carbon fiber bundle coated with a sizing agent, wherein the sizing agent on the carbon fiber bundle coated with the sizing agent also shows good solubility in water, and the residual sizing agent adhesion amount is reduced while the operability of the carbon fiber bundle coated with the sizing agent is excellent. The carbon fiber bundle coated with the sizing agent is formed by coating polyethylene glycol and / or a surfactant as a sizing agent on the carbon fiber bundle, and the carbon fiber bundle coated with the sizing agent satisfies all of the following (i) to (iii). (i) The sizing agent adhesion amount is not less than 0.15 parts by mass and not more than 0.80 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent. (ii) The dry F-F friction coefficient is not more than 0.39. (iii) The sizing agent adhesion amount after washing with water for 50 seconds under the conditions described in the specification is not more than 0.12 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

Description

Technical Field

[0001] The present invention relates to a carbon fiber bundle coated with a sizing agent, which exhibits bundling properties and friction characteristics suitable for the operability of a carbon fiber bundle coated with a sizing agent and exhibits good solubility in water in an aqueous process represented by a wet powder impregnation method, a carbon fiber bundle coated with a sizing agent, and a method for producing a carbon fiber bundle coated with a sizing agent. Background Art

[0002] Carbon fiber is not only lightweight but also excellent in strength and elastic modulus. Therefore, it is used in many fields such as aircraft parts, spacecraft parts, automobile parts, ship parts, civil engineering and construction materials, and sporting goods as a composite material combined with various matrix resins. As a representative form of a composite material using carbon fiber, a molded product formed by press molding (a molding method of degassing and shaping under pressure) a preform obtained by stacking prepreg blanks can be cited. The prepreg blank is usually manufactured by the following method: resin is impregnated into a carbon fiber substrate formed by arranging continuous carbon fiber bundles in a unidirectional manner. It is also proposed to use a composite material of discontinuous carbon fibers (chopped fibers, nets, etc.) that are excellent in shape tracking of complex shapes and can be molded in a short time, but in terms of mechanical properties such as specific strength and specific rigidity, and stability of properties, the practical performance of prepreg blanks as structural materials is excellent.

[0003] In recent years, carbon fiber composite materials have been required to have excellent molding properties, operability, and mechanical properties of the resulting molded products, and the industry also requires higher economic efficiency and productivity. As one of the responses to this requirement, the development of prepreg blanks using thermoplastic resins as matrix resins is underway. As an example of a manufacturing method, the following method can be cited: a thermoplastic resin slurry obtained by dispersing a powdered thermoplastic matrix resin using a surfactant is passed through to produce a carbon fiber tape having a powdered thermoplastic matrix resin, and the thermoplastic resin is impregnated into the interior of the carbon fiber tape using heat and pressure to produce it.

[0004] In order to bring out the excellent properties of carbon fiber after composite processing, it is important to have excellent operability during carbon fiber processing, reduce the entanglement of fluff, and breakage caused by entanglement. For carbon fiber bundles that are not coated with a sizing agent, there is no bundling, a large amount of fluff is generated, and the fluff gathers in the prepreg manufacturing process, and there is a situation where the quality of the prepreg deteriorates. Therefore, in order to improve the operability of the carbon fiber bundle, a sizing agent is usually applied to the carbon fiber bundle to impart a coating with friction resistance on the surface of the carbon fiber (see Patent Documents 1 and 2).

[0005] As for carbon fiber bundles, a method of cutting continuous fibers and dispersing them into single fibers for use as papermaking has also been proposed. The process of making paper from carbon fiber bundles is mostly a water-based process. In order to bring out the excellent properties of carbon fiber bundles, it is important to achieve both bundling properties (which are used to maintain the shape of carbon fiber bundles) and excellent fiber opening properties (which are used to quickly disperse into single fibers when the water medium is put into the papermaking process and inhibit re-aggregation) during the operation in the short-cut processing before the papermaking process, and a sizing agent that achieves both bundling properties and water dispersibility is applied. Usually, in order to improve the operability of carbon fiber bundles, epoxy resins and the like are mostly attached as bundling agents (sizing agents), but because the interaction of the sizing agent itself is strong and the interaction with the carbon fiber surface is too high, when applied to the water-based process, there is a tendency for the fiber opening properties in water to deteriorate. Therefore, for example, in Patent Documents 3 to 5, the following method is proposed: by using a surfactant or a water-soluble polymer as a sizing agent for the carbon fiber bundle, the operability when cut into chopped carbon fibers is improved, and the fiber opening properties in water are improved.

[0006] The excellent properties of carbon material composite materials have a great influence on the interface properties of carbon fiber and resin. Therefore, the properties of the sizing agent present in the interface between carbon fiber and resin become important. For example, Patent Document 6 proposes a method in which a surfactant is applied to a carbon fiber bundle and then a sizing agent is applied, thereby uniformly applying the sizing agent to obtain a carbon fiber composite material with excellent mechanical properties. In addition, Patent Document 7 proposes a method in which a surfactant is applied to the spinning of refractory fibers to improve the affinity with the powdered matrix resin and improve the impregnation when manufacturing the aggregate.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: U.S. Patent No. 3957716

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 57-171767

[0011] Patent Document 3: International Publication No. WO2006 / 019139 Pamphlet

[0012] Patent Document 4: Japanese Patent Application Publication No. 2000-54269

[0013] Patent Document 5: Japanese Patent No. 6571892

[0014] Patent Document 6: Japanese Patent Application Publication No. 2017-137603

[0015] Patent Document 7: Japanese Patent Application Laid-Open No. 59-144679 Summary of the invention

[0016] Problems to be solved by the invention

[0017] On the other hand, when the handling properties and interface characteristics are controlled by applying a sizing agent to the carbon fiber bundle as described above, when combined with a thermoplastic matrix resin that requires a high molding temperature, the heat resistance of the matrix resin is reduced or the adhesion between the carbon fiber and the matrix resin is reduced depending on the composition of the sizing agent. As a result, there are cases where CFRP cannot exhibit sufficient performance.

[0018] That is, although research has been conducted on suppressing the fuzzing of carbon fiber bundles by applying sizing agents and improving the processability in water-based processes, in carbon fiber processing using water-based processes, considering that high mechanical properties represented by the strand strength of the carbon fiber bundle are imparted to the composite material, on the basis of applying sizing agents to simultaneously achieve the suppression of fuzz generation caused by single fiber breakage of the carbon fiber bundle and fiber openability in water, from the perspective of minimizing the risk of the above-mentioned influence on the thermoplastic matrix resin in high-order processing, there is no concept of removing the sizing agent from the carbon fiber.

[0019] The present invention is made in view of the above situation, and its purpose is to provide a carbon fiber bundle coated with a sizing agent, wherein the carbon fiber bundle coated with the sizing agent has excellent operability, the sizing agent on the carbon fiber bundle coated with the sizing agent also shows good solubility in water, and the residual sizing agent adhesion amount is reduced, thereby being particularly suitable for combination with a thermoplastic matrix resin.

[0020] Means for solving problems

[0021] The present invention for solving the above-mentioned problems is a carbon fiber bundle coated with a sizing agent, wherein polyethylene glycol and / or a surfactant is coated on the carbon fiber bundle as a sizing agent, and the carbon fiber bundle coated with a sizing agent satisfies all of the following (i) to (iii).

[0022] (i) The amount of the sizing agent applied is 0.15 to 0.80 parts by mass based on 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

[0023] (ii) The dry FF friction coefficient is 0.39 or less.

[0024] (iii) The amount of sizing agent deposited after washing with water for 50 seconds under the conditions described in the specification is 0.12 parts by mass or less.

[0025] In addition, the method for producing a carbon fiber bundle coated with a sizing agent of the present invention is the above-mentioned method for producing a carbon fiber bundle coated with a sizing agent, characterized in that the production method has a drying step of drying the carbon fiber bundle coated with the sizing agent at 120 to 260°C after the step of applying a sizing agent containing polyethylene glycol and / or a surfactant to the carbon fiber bundle.

[0026] Effects of the Invention

[0027] According to the present invention, a carbon fiber bundle coated with a sizing agent can be obtained. When the carbon fiber bundle coated with the sizing agent has excellent operability, the sizing agent on the carbon fiber bundle coated with the sizing agent also shows good solubility in water, and the amount of sizing agent remaining after processing is reduced, thereby being particularly suitable for combination with a thermoplastic matrix resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [ Figure 1 ] Figure 1 This is a diagram showing the evaluation method of 50-second water washing.

[0029] [ Figure 2 ] Figure 2 This is a diagram showing the evaluation method of 25-second water washing. DETAILED DESCRIPTION

[0030] Hereinafter, a mode for carrying out the present invention will be described.

[0031] The sizing agent-coated carbon fiber bundle of the present invention is obtained by coating a carbon fiber bundle with polyethylene glycol and / or a surfactant as a sizing agent, and satisfies all of the following (i) to (iii).

[0032] (i) The amount of the sizing agent applied is 0.15 parts by mass or more and 0.80 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

[0033] (ii) The dry FF friction coefficient is 0.39 or less.

[0034] (iii) The amount of sizing agent adhered after washing with water for 50 seconds under the conditions described in the specification is 0.12 parts by mass or less based on 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

[0035] According to the research of the inventors of the present application, when a sizing agent is used and the operability becomes good after being applied to a carbon fiber bundle, there is a problem that the solubility of the sizing agent on the carbon fiber bundle coated with the sizing agent in water decreases, the sizing agent is easy to remain, and the mechanical properties are easy to decrease when making a prepreg. With respect to this problem, it is found that even when a compound with high operability is used for the sizing agent, by using a sizing agent containing polyethylene glycol and / or a surfactant, controlling the amount of sizing agent attached and the friction coefficient, and controlling the amount of sizing agent attached after washing, it is possible to simultaneously achieve high operability of the carbon fiber bundle coated with the sizing agent and good solubility of the sizing agent in water.

[0036] The sizing agent constituting the present invention needs to contain polyethylene glycol and / or a surfactant, and the sizing agent applied to the carbon fiber bundle needs to meet specific conditions. The surfactant referred to here refers to anionic surfactants, nonionic surfactants, and amphoteric surfactants.

[0037] Anionic surfactants are surfactants with anionic hydrophilic groups. When a carbon fiber bundle coated with anionic surfactants is placed in water, the solubility of the sizing agent is improved. As a result, the sizing agent remaining in the carbon fiber bundle is reduced. Although the mechanism is not clear, it is believed that the anionic surfactant is ionized in water, and the anionic hydrophilic group repels the carbon fiber surface, thus showing excellent solubility.

[0038] Examples of the anionic surfactant include carboxylates, sulfonates, carboxylates and sulfonates, sulfate ester salts, and phosphate ester salts.

[0039] As a specific example of carboxylate, soap, polyoxyethylene alkyl ether carboxylate, alkyl hydroxy ether carboxylate, etc. can be cited. As a specific example of sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkanoyl methyl amino ethanesulfonic acid, dialkyl sulfosuccinate salt, etc. can be cited. As a specific example of carboxylate and sulfonate, alkyl sulfosuccinate disalt, polyoxyethylene alkyl ether sulfosuccinate disalt, etc. can be cited. As a specific example of sulfate ester salt, high-level alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, sulfated oil, sulfated fatty acid ester, sulfated olefin, etc. can be cited. As a specific example of phosphate ester salt, high-level alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, dithiophosphate ester salt, etc. can be cited. The cations constituting the salt include cations of alkali metals such as sodium and cations of alkaline earth metals such as calcium. In order to improve water solubility, cations of alkali metals are preferred. In addition, ammonium salts can also be used instead of metal salts.

[0040] The so-called nonionic surfactant refers to a surfactant having a non-ionized hydrophilic group. When the carbon fiber bundle coated with polyethylene glycol and / or a nonionic surfactant is placed in water, the solubility of the sizing agent is improved. As a result, the sizing agent remaining in the carbon fiber bundle is reduced. Although the mechanism is not clear, it is believed that the hydrophilic group part of the polyethylene glycol and / or nonionic surfactant easily interacts with water and exhibits excellent solubility.

[0041] Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, and polyoxyethylene octadecyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene alkylphenyl ether, sorbitan fatty acid esters such as sorbitan monooleate, sorbitan monostearate, and sorbitan trioleate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate, polyoxyethylene glyceryl fatty acid esters such as polyoxyethylene glyceryl monooleate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan tetraoleate, and polyethylene glycol fatty acid esters such as PEG monocaprylate, PEG monoheptanoate, PEG monononanoate, PEG monopentadecanoate, PEG monopalmitate, PEG monolinoleate, PEG dilaurate, PEG monooleate, PEG dioleate, PEG monostearate, PEG distearate, PEG dilaurate, and PEG dilinoleate. Each of these nonionic surfactants can be used alone or in combination of two or more, or in combination with PEG. It should be noted that "PEG" is an abbreviation for "polyethylene glycol".

[0042] When polyethylene glycol is combined with a nonionic surfactant, it is preferred that the polyethylene glycol is 50 parts by mass or more relative to 100 parts by mass of the total amount of the mixture. By making the polyethylene glycol 50 parts by mass or more, the solubility is improved by utilizing the hydrophilicity of the polyethylene glycol, so that the sizing agent is easily dissolved during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced. The mixing ratio of polyethylene glycol is more preferably 70 parts by mass or more in 100 parts by mass.

[0043] Amphoteric surfactants are surfactants that have anionic and cationic sites in the same molecule. When a carbon fiber bundle coated with an amphoteric surfactant is placed in water, the solubility of the sizing agent is improved. As a result, the amount of sizing agent remaining in the carbon fiber bundle is reduced. Although the mechanism is not clear, it is believed that the hydrophilic group part of the amphoteric surfactant is different from other nonionic, anionic, and cationic surfactants, and is easy to interact with water in a wide pH range, showing excellent solubility.

[0044] Examples of the types of amphoteric surfactants include amino acid-based surfactants, betaine-based surfactants, sulfobetaine-based surfactants, and amine oxide-based surfactants.

[0045] Specific examples of the amphoteric surfactant include fatty acid amide propyl betaine, myristic acid amide propyl betaine, lauric acid amide propyl betaine, cocoamidopropyl betaine, fatty acid amide propyl dimethylaminoacetic acid betaine, lauric acid amide propyl dimethylaminoacetic acid betaine, octadecyl dimethylaminoacetic acid betaine, lauryl dimethylaminoacetic acid betaine, lauryl dihydroxyethyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and other betaine-type surfactants, alkyl hydroxysulfonates, cocoamidopropyl Sulfobetaine-type surfactants such as hydroxysulfobetaine and laurylamidopropyl hydroxysulfobetaine, amine oxide-type surfactants such as fatty acid amide propyl dimethyl amine oxide, lauric acid amide propyl dimethyl amine oxide, lauryl dimethyl amine oxide, coconut oil alkyl dimethyl amine oxide, dodecyl dimethyl amine oxide, decyl dimethyl amine oxide, and tetradecyl dimethyl amine oxide, alkyl carboxymethyl hydroxyethyl imidazolium betaine, lauryl dimethylaminoacetic acid betaine, alkyl diaminoethyl glycine hydrochloride, and sodium laurylaminodipropionate, etc.

[0046] Whether the carbon fiber bundle coated with the sizing agent contains polyethylene glycol and / or a surfactant can be determined by extracting the sizing agent from the carbon fiber bundle coated with the sizing agent with water and evaluating it. There is a method in which the sizing agent after water extraction is freeze-dried and then a structural evaluation based on an IR spectrum obtained by infrared spectroscopy is combined with a proton NMR and mass spectrometry evaluation of the freeze-dried solid.

[0047] The amount of the sizing agent attached to the carbon fiber bundle coated with the sizing agent of the present invention needs to be 0.15 to 0.80 parts by mass based on 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

[0048] By making the amount of sizing agent attached to be 0.15 parts by mass or more, the operability of the carbon fiber bundle coated with the sizing agent can be improved, the generation of fluff during manufacturing and processing can be suppressed, and the quality of the carbon fiber bundle such as smoothness can be improved. The amount of attachment is preferably 0.25 parts by mass or more, and more preferably 0.30 parts by mass or more. On the other hand, by making the amount of sizing agent attached to be 0.80 parts by mass or less, the residual amount can be reduced in a short time, thereby reducing the influence on the mechanical properties of the composite material. The amount of sizing agent attached is preferably 0.60 parts by mass or less, and more preferably 0.45 parts by mass or less.

[0049] The dry FF friction coefficient of the carbon fiber bundle coated with the sizing agent of the present invention needs to be 0.39 or less. Below 0.39, the friction between the monofilaments in the carbon fiber bundle is reduced, so the fluff generated by friction when the carbon fiber bundle is pulled out from the bobbin and the fluff generated by friction in the bundle when it contacts the metal rod are reduced. It is more preferably below 0.36, and further preferably below 0.30. In addition, it is preferably above 0.15. When it is less than 0.15, it is not easy to apply force between the monofilaments, and the bundling property is easily reduced. The dry FF friction coefficient can be controlled by the roughness of the carbon fiber surface, the type and amount of the anionic surfactant contained in the sizing agent, or more simply, the drying temperature after the sizing agent is applied. In addition, it can also be controlled by the amount of sizing agent attached, etc. The evaluation procedure of the dry FF friction coefficient specified in the present invention is described in the examples.

[0050] <Calculation method of the amount of sizing agent adhered after 50 seconds of washing>

[0051] The carbon fiber bundle coated with the sizing agent of the present invention needs to have an amount of sizing agent attached after washing in water for 50 seconds of 0.12 parts by mass or less. If the residual sizing agent is reduced by extending the washing time, the contribution of the surface functional groups of the carbon fiber to the physical properties of the matrix resin becomes larger, and the mechanical properties are improved, so it is preferred. When it is less than 0.12 parts by mass, the effect of the sizing agent on the matrix resin decreases, the contribution of the surface functional groups of the carbon fiber to the physical properties of the matrix resin becomes larger, and the mechanical properties are improved. It is preferably less than 0.08 parts by mass, and more preferably less than 0.06 parts by mass.

[0052] Here, the method of washing the carbon fiber bundle coated with the sizing agent for 50 seconds in water as specified in the present invention can be carried out by the following steps. The carbon fiber bundle coated with the sizing agent is introduced into water via a roller to dissolve the sizing agent in the water. The washing step is shown in Figure 1. The washing of the carbon fiber bundle coated with the sizing agent can be performed using the following steps. The carbon fiber bundle 1a coated with the sizing agent set in the unwinding process 11 is passed through the water 1d in the water washing tank 18 via the free roller 15 before the water washing tank, the free roller 16 in the water washing tank, and the free roller 17 after the water washing tank in the water washing process 12, and then, it is passed through the water 1e in the water washing tank 22 via the same free roller 19 before the water washing tank, the free roller 20 in the water washing tank, and the free roller 21 after the water washing tank, and then continuously passes through the drying process 13 to dry the water, and is wound in the winding process 14. The water temperature is set to 25°C, the unwinding tension from the creel is set to 800g, the process speed is set to 2.4m / min, the diameter of the free roller in the water washing tank is set to 150mm, and the contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level was adjusted so that the water passing time in one washing tank was 25 seconds, and the total passing time in the two washing tanks was 50 seconds. The drying process was non-contact drying, and the washed carbon fiber bundle 1b coated with the sizing agent was dried at a drying temperature of 150°C for 1 minute to obtain a washed and dried carbon fiber bundle 1c coated with the sizing agent. The sizing agent adhesion amount of the washed and dried carbon fiber bundle 1c coated with the sizing agent was measured to obtain the sizing agent adhesion amount.

[0053] <Calculation method of sizing agent adhesion after 25 seconds of water washing>

[0054] The amount of sizing agent attached to the carbon fiber bundle coated with the sizing agent of the present invention after washing in water for 25 seconds is preferably 0.12 parts by mass or less. When it is 0.12 parts by mass or less, the effect of the sizing agent on the matrix resin is reduced, the surface functional groups of the carbon fibers contribute more to the physical properties of the matrix resin, and the mechanical properties are improved. More preferably, it is 0.08% by mass or less.

[0055] Here, the method of washing the carbon fiber bundle coated with the sizing agent for 25 seconds specified in the present invention can be carried out by the following steps. The carbon fiber bundle coated with the sizing agent is introduced into water via a roller to dissolve the sizing agent in the water. The washing step is shown in Figure 2. The carbon fiber bundle 1a coated with the sizing agent set in the unwinding process 11 passes through the water 1d in the water washing tank 18 through the free roller 15 before the water washing tank, the free roller 16 in the water washing tank, and the free roller 17 after the water washing tank in the water washing process 12, and then passes through the drying process 13 continuously to dry the water, and is wound in the winding process 14. The water temperature is set to 25°C, the unwinding tension from the creel is set to 800g, the process speed is set to 2.4m / min speed, the diameter of the free roller in the water washing tank is set to 150mm, and the contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in such a way that the passing time in the water becomes 25 seconds. The drying process is non-contact drying, and the carbon fiber bundle 1b coated with the sizing agent after water washing is dried at a drying temperature of 150°C for 1 minute to obtain a carbon fiber bundle 1c coated with the sizing agent after water washing and drying. The sizing agent adhesion amount is obtained by measuring the sizing agent adhesion amount of the carbon fiber bundle 1c coated with the sizing agent after washing and drying.

[0056] The wet FM friction coefficient of the carbon fiber bundle coated with a sizing agent constituting the present invention is preferably 0.28 or less. In the aqueous thermoplastic matrix resin impregnation process in which a thermoplastic matrix resin is impregnated into a carbon fiber bundle coated with a sizing agent in an aqueous solvent, there is a lot of friction with guide rods and rollers not only in the air but also in water, which becomes the main cause of fuzzing. When it is less than 0.28, the friction force generated between stainless steel SUS304 and the fiber becomes smaller, and the fuzz caused by friction is reduced, so it is preferred. It is preferably less than 0.27, and more preferably less than 0.25. In the present invention, stainless steel SUS304 with a surface roughness of 0.8 to 1S is used in the evaluation of the friction coefficient. The friction coefficient between the fiber and stainless steel SUS304 can be controlled by the roughness of the carbon fiber surface, the type and amount of anionic surfactant contained in the sizing agent, or more simply, the drying temperature after the sizing agent is applied. In addition, it can also be controlled by the amount of sizing agent attached, etc. The evaluation procedure of the friction coefficient between the fiber and stainless steel SUS304 specified in the present invention is described in the examples.

[0057] In the sizing agent constituting the present invention, the weight average molecular weight Mw of each of the anionic surfactant, polyethylene glycol, nonionic surfactant, and amphoteric surfactant is preferably 150 to 5000. It should be noted that the above-mentioned weight average molecular weight Mw is measured by gel permeation chromatography (hereinafter referred to as GPC) method and obtained using polyethylene glycol as a standard substance. The larger the Mw, the higher the viscosity, so the rate of dissolution from the carbon fiber surface decreases.

[0058] By making Mw less than 5000, the index of the activity ease of anionic surfactants, polyethylene glycol, nonionic surfactants, and amphoteric surfactants, i.e., viscosity, is decreased, so that the entanglement amount of the molecular chain when dissolved in water is reduced, thereby the dissolution of anionic surfactants, polyethylene glycol, nonionic surfactants, and amphoteric surfactants in water is improved. Mw is more preferably less than 600, and more preferably less than 500. On the other hand, from the aspect of coating, the larger the Mw, the more it can suppress the volatilization of the sizing agent during coating. The lower limit of Mw is preferably more than 150, and more preferably more than 200. Regarding the weight average molecular weight Mw of anionic surfactants, polyethylene glycol, nonionic surfactants, and amphoteric surfactants applied on a carbon fiber bundle coated with a sizing agent, it can be confirmed by combining the operation of extracting the sizing agent from the carbon fiber bundle coated with the sizing agent with water and performing GPC evaluation, and the operation of identifying metal elements by elemental analysis such as XPS.

[0059] In the sizing agent of the present invention, the total amount of surfactant is 70 parts by mass or more based on 100 parts by mass of the total amount of the sizing agent, and the anionic surfactant, polyethylene glycol, nonionic surfactant and / or amphoteric surfactant is preferably 50 parts by mass or more of the total amount of surfactant.

[0060] By making the total amount of the surfactant 70 parts by mass or more, the solubility is improved by the hydrophilic group in the surfactant, so that the sizing agent is easily dissolved during water washing, and the residual amount of the sizing agent on the carbon fiber bundle can be reduced. Preferably, it is 85 parts by mass or more, and more preferably 95 parts by mass or more. In addition, by making the polyethylene glycol and / or nonionic surfactant 50 parts by mass or more of the total amount of the surfactant, the hydrophilic group part of the polyethylene glycol and / or nonionic surfactant easily interacts with water, and the sizing agent is easily dissolved during water washing, which can reduce the residual amount of the sizing agent on the carbon fiber bundle.

[0061] In the sizing agent constituting the present invention, the lipophilic-hydrophilic balance (HLB) of the nonionic surfactant is preferably 15 to 20; or, the HLB is 12 to 15, and the hydroxyl ratio at the molecular chain end is 50% or more. The HLB specified in the present invention is a value calculated based on the molecular structure according to the Griffin method described in "New Introduction to Surfactants", page 128, (1992). By making the HLB of the nonionic surfactant 15 to 20, the hydrophilicity of the nonionic surfactant is improved, so that the sizing agent is easily dissolved during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced. The HLB is preferably 16 or more. In addition, even if the HLB is 12 to 15, the hydroxyl ratio at the molecular chain end is 50% or more, so that the solubility of the nonionic surfactant in water is improved by virtue of the hydrophilicity of the terminal part, so that the sizing agent is easily dissolved during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced.

[0062] In the sizing agent constituting the present invention, the weight average molecular weight Mw of polyethylene glycol and / or nonionic surfactant is preferably 300 or more and 5000 or less. It should be noted that the above-mentioned weight average molecular weight Mw is measured by gel permeation chromatography (hereinafter, abbreviated as GPC) method, and obtained with polyethylene glycol as a standard substance. The larger the Mw, the higher the viscosity of polyethylene glycol and / or nonionic surfactant, so the speed of dissolution from the carbon fiber surface decreases. By making Mw less than 5000, the index of the ease of activity of polyethylene glycol and / or nonionic surfactant, i.e., the viscosity, is reduced, and the entanglement amount of the molecular chain when dissolved in water is reduced, thereby improving the solubility of polyethylene glycol and / or nonionic surfactant in water. Mw is preferably less than 2000, and more preferably less than 1000. On the other hand, from the aspect of coating, the larger the Mw, the more it can suppress the volatilization of the sizing agent when it is coated. The Mw lower limit is preferably more than 300. The molecular weight of the polyethylene glycol and / or nonionic surfactant coated on the carbon fiber bundle coated with the sizing agent can be confirmed by extracting the sizing agent from the carbon fiber bundle coated with the sizing agent with water and performing GPC evaluation.

[0063] In addition, by making the anionic surfactant more than 50 parts by mass of the total amount of surfactants, the hydrophilic group in the anion of the anionic surfactant repels the carbon fiber surface and the solubility is improved. Therefore, the sizing agent is easily dissolved during water washing, and the residual amount of sizing agent on the carbon fiber bundle can be reduced.

[0064] In addition, in addition to polyethylene glycol and / or surfactant, other components may also be included. Hereinafter, other components are sometimes referred to as the second component. As other components, aliphatic or alicyclic compounds and / or aliphatic or alicyclic compounds in which two hydroxyls are bonded to two different carbon atoms, polyvinyl alcohol, polyglycidyl ether, polyethyleneimine, etc. may be cited, and aliphatic or alicyclic compounds and / or aliphatic or alicyclic compounds in which two hydroxyls are bonded to two different carbon atoms are particularly preferred.

[0065] Here, in addition to polyethylene glycol and / or surfactant, it is preferred to further include 0.1 mass parts or more and 30 mass parts or less of an aliphatic or alicyclic compound having one hydroxyl group bonded to carbon and / or an aliphatic or alicyclic compound having two hydroxyl groups bonded to two different carbons (alcohol, diol) relative to 100 mass parts of the total amount of the sizing agent. By setting it to 0.1 mass parts or more, the lipophilic group on the carbon fiber surface can be exposed to the air interface, and friction can be reduced, so it is preferred, and 20 mass parts or more can show the effect more uniformly, so it is further preferred.

[0066] Specific examples of aliphatic or alicyclic compounds in which one and / or two hydroxyl groups are bonded to carbon include methanol, 2-propanol, n-butanol, isobutanol, n-decanol, myristyl alcohol, aliphatic alcohols such as ethylene glycol and propylene glycol, alicyclic alcohols such as cyclohexanol, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 1,6- aliphatic diols such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyldecane-4,7-diol; and alicyclic diols such as hexanediol, cyclohexanediol and 1,4-cyclohexanedimethanol.

[0067] In the sizing agent constituting the present invention, it is preferred that the ratio of the hydrophilic group in the anion constituting the anionic surfactant is 17% or more.

[0068] By making the hydrophilic group ratio in the anion 17% or more, the solubility of the anion part in water is improved, so the sizing agent is easily eluted during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced. It is preferably 20% or more, and more preferably 30% or more.

[0069] The hydrophilic group ratio is calculated based on the molecular weight of the anionic surfactant. It can be calculated based on the ratio of the molecular weight of the hydrophilic group of the anion of the anionic surfactant to the molecular weight of the anionic surfactant. The so-called hydrophilic group here is equivalent to the sulfate group (SO 4 -), sulfonic acid (SO 3 - ), carboxyl (COO - ), phosphate group (HPO 3 - ), hydroxyl (OH - ) and other sites with negative charges. In addition, when an unreacted portion remains during the manufacture of the anionic portion of the surfactant, the reaction rate is calculated based on the sum of the starting material and the reacted material (the anion of the anionic surfactant) and the amount of the reacted material, and the reaction rate is multiplied by the hydrophilic group ratio (the hydrophilic group ratio is calculated based on the molecular weight of the anionic portion of the anionic surfactant), and the value thus obtained is calculated as the hydrophilicity of the anionic portion of the present invention.

[0070] In the sizing agent constituting the present invention, the weight average molecular weight Mw of the anionic surfactant is preferably 150 to 600. The larger the Mw, the higher the proportion of the hydrophobic group of the anionic surfactant, and therefore the rate of dissolution from the carbon fiber surface decreases. By making the Mw less than 600, the index of the dissolution property of the anionic surfactant, i.e., the hydrophilic group ratio, is increased, thereby improving the dissolution property of the anionic surfactant in water. The Mw is preferably less than 500. On the other hand, from the aspect of processability, the larger the Mw, the more solid the sizing agent film is and the friction can be reduced. The Mw lower limit is further preferably more than 250. The weight average molecular weight Mw of the anionic surfactant coated on the carbon fiber bundle coated with the sizing agent can be confirmed by combining the operation of water extraction of the sizing agent from the carbon fiber bundle coated with the sizing agent and performing GPC evaluation with the operation of identifying the metal element by elemental analysis such as XPS.

[0071] In addition, by making the amphoteric surfactant account for 50 parts by mass or more of the total amount of the surfactant, the hydrophilic group portion of the amphoteric surfactant interacts with water and the solubility is improved. Therefore, the sizing agent is easily eluted during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced.

[0072] In the sizing agent constituting the present invention, it is preferred that the average carbon number of the alkyl group constituting the amphoteric surfactant is 17 or less.

[0073] By making the average carbon number of the alkyl group 17 or less, the solubility of the amphoteric surfactant in water is improved, so that the sizing agent is easily dissolved during water washing, and the amount of sizing agent remaining on the carbon fiber bundle can be reduced. The average carbon number of the alkyl group is more preferably 16.5 or less, and further preferably 16 or less. In addition, 8 or more is preferred. When the average carbon number is less than 8, the surface free energy of the sizing agent becomes large, so the dry FF friction coefficient becomes high.

[0074] The average number of carbon atoms of the alkyl group constituting the amphoteric surfactant can be evaluated by extracting the sizing agent from the carbon fiber bundle coated with the sizing agent with water and evaluating the extraction. There is a method in which the sizing agent after water extraction is freeze-dried and then the structural evaluation based on the IR spectrum obtained by infrared spectroscopy is combined with the proton NMR, carbon NMR and mass spectrometry evaluation of the freeze-dried solid.

[0075] <Method for determining the absorbance of carbon fiber extract>

[0076] For the carbon fiber bundle coated with a sizing agent constituting the present invention, the absorbance of the water extract is preferably 0.06 or more. By setting the absorbance to 0.06 or more, contaminants such as oxides attached to the surface of the carbon fiber are easily removed, and the adhesiveness is improved. The absorbance is preferably 0.08 or more, and more preferably 0.10 or more.

[0077] Here, the absorbance of the aqueous extract of the sizing agent-coated carbon fiber extract specified in the present invention can be determined by the following procedure. 1.0 g of carbon fiber bundle is cut out and placed in a 20 cm 3 Add 10.0 g of distilled water at 25°C to a covered glass container. Set the amplitude of the shaker to 30 mm and the shaking speed to 120 rpm, place the glass container in the shaker, and shake for 1 minute. After shaking, immediately remove the carbon fiber bundle from the solution. Put the solution extracted from the carbon fiber into a quartz cell with a light path length of 1.0 cm, use distilled water as the reference solution, use a UV-visible spectrophotometer to measure the absorbance from 200 to 900 nm, and record the absorbance at 600 nm.

[0078] The shaker used was a water bath shaker SB-13 manufactured by AS ONE Co., Ltd. The ultraviolet-visible spectrophotometer used was V-5507 manufactured by JASCO Corporation.

[0079] In the sizing agent constituting the present invention, the weight average molecular weight Mw of the amphoteric surfactant is preferably 150 to 600. The larger the Mw, the higher the viscosity of the amphoteric surfactant, and therefore the rate of dissolution from the carbon fiber surface decreases. By making the Mw less than 600, the viscosity, an index of the dissolution property of the anionic surfactant, can be reduced, and the dissolution property of the amphoteric surfactant in water is improved. Mw of 250 or less is more preferred. On the other hand, from the aspect of coating, the larger the Mw, the more it can suppress the volatilization of the sizing agent during coating. The lower limit of Mw is preferably 150 or more. The weight average molecular weight Mw of the amphoteric surfactant applied to the carbon fiber bundle coated with the sizing agent can be confirmed by combining the operation of water extracting the sizing agent from the carbon fiber bundle coated with the sizing agent and performing GPC evaluation, and the operation of identifying the metal element by elemental analysis such as XPS.

[0080] In the sizing agent constituting the present invention, it is preferred that the mass residual rate of the coated polyethylene glycol and / or surfactant at 300°C when the temperature is increased at 10°C / min in air is 35% or less. By making the mass residual rate 35% or less, the low heat-resistant component of the sizing agent is decomposed before the matrix resin melts, and the amount of sizing agent entering the matrix resin is reduced, thereby reducing the influence on the mechanical properties of the composite material and stabilizing the physical properties. It is preferably 20% or less, and more preferably 5% or less.

[0081] In the sizing agent constituting the present invention, the mass residual rate of the coated polyethylene glycol and / or surfactant when the temperature is raised at 10°C / min in air to 350°C is preferably 35% or less. By making the mass residual rate 30% or less, the low heat-resistant components of the sizing agent are decomposed before the highly heat-resistant matrix resin melts, and the amount of sizing agent entering the matrix resin is reduced, thereby reducing the influence on the mechanical properties of the composite material and stabilizing the physical properties. It is preferably 25% or less, and more preferably 5% or less.

[0082] Next, components constituting the carbon fiber bundle coated with a sizing agent used in the present invention will be described.

[0083] The carbon fiber bundle used in the present invention is not particularly limited, but polyacrylonitrile carbon fibers can be preferably used from the viewpoint of mechanical properties. The polyacrylonitrile carbon fiber bundle is obtained by subjecting a carbon fiber precursor fiber formed of a polyacrylonitrile polymer to flame retardant treatment at a maximum temperature of 200 to 300° C. in an oxidizing atmosphere, then subjecting it to a pre-carbonization treatment at a maximum temperature of 500 to 1200° C. in an inert atmosphere, and then subjecting it to a carbonization treatment at a maximum temperature of 1200 to 2000° C. in an inert atmosphere.

[0084] The strand strength of the carbon fiber bundle of the present invention is preferably 4.0 GPa, more preferably 4.9 GPa or more. If the strand strength of the carbon fiber bundle is 4.0 GPa or more, the strand strength of the carbon fiber bundle after washing away the sizing agent is sufficiently high, and the mechanical properties of the composite material can be easily improved.

[0085] In the present invention, in order to improve the adhesion between the carbon fiber bundle and the matrix resin, it is preferred to introduce oxygen-containing functional groups to the surface by subjecting the carbon fiber bundle to oxidation treatment. As the oxidation treatment method, gas phase oxidation, liquid phase oxidation and liquid phase electrolytic oxidation can be used. Liquid phase electrolytic oxidation can be preferably used from the viewpoint of high productivity and uniform treatment.

[0086] In the present invention, as the electrolyte used in the liquid phase electrolytic oxidation, an acidic electrolyte and an alkaline electrolyte can be cited. As the acidic electrolyte, for example, inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, boric acid, and carbonic acid, organic acids such as acetic acid, butyric acid, oxalic acid, acrylic acid, and maleic acid, or salts of ammonium sulfate, ammonium bisulfate, etc. can be cited. Among them, sulfuric acid and nitric acid showing strong acidity can be preferably used. As the alkaline electrolyte, specifically, aqueous solutions of hydroxides such as sodium hydroxide, calcium hydroxide and barium hydroxide, aqueous solutions of carbonates such as sodium carbonate, calcium carbonate, barium carbonate and ammonium carbonate, aqueous solutions of bicarbonates such as sodium bicarbonate, calcium bicarbonate, barium bicarbonate and ammonium bicarbonate, aqueous solutions of ammonia, tetraalkylammonium hydroxide and hydrazine, etc. can be cited.

[0087] The carbon fiber bundle in the present invention preferably has a surface oxygen concentration of 0.08 or more and 0.25 or less as measured by X-ray photoelectron spectroscopy.

[0088] By having functional groups on the surface of the carbon fiber, affinity with the matrix resin is generated, and high adhesion can be exhibited. When the surface oxygen concentration (O / C) is less than 0.08, the affinity between the carbon fiber surface and the matrix resin decreases, and the bonding strength decreases. The surface oxygen concentration is preferably above 0.15. When it is above 0.15, the affinity between the carbon fiber surface and the matrix resin becomes higher, so it is preferred. In addition, O / C is more preferably below 0.25. When O / C exceeds 0.25, although the functional groups increase, the surface layer of the carbon fiber is easy to peel off, so the bonding strength decreases.

[0089] Next, the method for producing a carbon fiber bundle coated with a sizing agent according to the present invention will be described.

[0090] First, a method for applying (providing) the sizing agent constituting the present invention to a carbon fiber bundle will be described.

[0091] In the present invention, the sizing agent is preferably diluted with a solvent and used in a uniform solution form. As such a solvent, for example, water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, dimethylformamide, and dimethylacetamide etc. can be cited, wherein water can be preferably used because it is advantageous from the viewpoint of easy operation and safety.

[0092] As a coating method, for example, there is a method of immersing a carbon fiber bundle in a sizing agent solution via a roller, a method of contacting a carbon fiber bundle with a roller to which a sizing agent solution is attached, a method of making a sizing agent solution mist and spraying it on a carbon fiber bundle, etc. When manufacturing a carbon fiber bundle coated with a sizing agent of the present invention, it is preferred to use a method of immersing the carbon fiber bundle in a sizing agent solution via a roller. In addition, the method of imparting the sizing agent can be any of a batch type or a continuous type, preferably using a continuous type with good productivity and capable of reducing deviations. In addition, when imparting the sizing agent, vibrating the carbon fiber bundle with ultrasound is also a preferred method.

[0093] In the present invention, after applying the sizing agent solution, it is preferred to use a contact drying method, for example, by bringing the carbon fiber bundle into contact with a heated roller to obtain a carbon fiber bundle coated with a sizing agent. The carbon fiber bundle introduced into the heated roller is pressed against the heated roller due to tension and is quickly dried, so that the flat shape of the carbon fiber bundle widened by the heated roller is easily fixed by the sizing agent. The contact area between the single fibers of the carbon fiber bundle in a flat shape is small, so when immersed in water, the contact area with water increases, and the solubility tends to become higher. The temperature of the contact drying method is preferably 120°C or more. When it is 120°C or more, the carbon fiber bundle is easily fixed in a flat shape. It is more preferably 130°C or more. In addition, in the present invention, after passing through the heated roller as a pre-drying process, a heat treatment can be further applied as a second drying process. In the heat treatment as the second drying process, a non-contact heating method that is easy to implement heat treatment at high temperature is preferred. By performing this heat treatment, the dilution solvent remaining in the sizing agent can be further removed, and the viscosity of the sizing agent can be stabilized, so that the solubility can be stably improved.

[0094] In addition, by performing this heat treatment, the surface free energy of the polyethylene glycol and / or surfactant on the carbon fiber can be controlled, and the friction coefficient can be reduced, so that the operability of the carbon fiber bundle coated with the sizing agent can be improved. As the heat treatment temperature, the temperature range of 120 to 260°C is preferred. When it is above 120°C, the ionization of the anionic surfactant or the amphoteric surfactant is controlled by removing the dilution solution, and the electrical interaction can be suppressed, so it is easy to improve the operability. In addition, the viscosity caused by the interaction between the polyethylene glycol and / or the nonionic surfactant and water is reduced, which makes it easy to improve the operability. It is preferably above 150°C, and more preferably above 180°C. On the other hand, by setting the upper limit of the heat treatment temperature to below 260°C, the thermal degradation of the polyethylene glycol and / or surfactant components can be suppressed, and the solubility can be easily maintained. It is preferably below 240°C, and more preferably below 220°C.

[0095] Furthermore, the heat treatment may be performed by microwave irradiation and / or infrared irradiation.

[0096] Example

[0097] Next, the present invention will be specifically described using examples, but the present invention is not limited to these examples.

[0098] <Method for measuring the amount of sizing agent adhered>

[0099] Weigh 2.0±0.5 g of the carbon fiber bundle coated with the sizing agent and record it as (W 1 ) (read to the fourth decimal place), and then in a 50 ml / min nitrogen flow, in an electric furnace (capacity 120 cm 3 ) for 15 minutes to allow the sizing agent to be completely thermally decomposed. Then, the carbon fiber bundle was moved to a container in a 20 liter / minute dry nitrogen flow, and the carbon fiber bundle was weighed after cooling for 15 minutes and recorded as (W 2 )(read to the 4th decimal place), according to W 1 -W 2 The heating reduction amount is calculated. The heating reduction amount is converted into mass parts relative to 100 mass parts of the carbon fiber bundle coated with the sizing agent, and the obtained value (rounded off to the third decimal place) is used as the attached amount of the sizing agent (mass parts). Two measurements are performed, and the average value is used as the attached amount of the sizing agent.

[0100] <Method for measuring the residual mass ratio of polyethylene glycol and / or surfactant>

[0101] The residual mass ratio of the sizing agent such as polyethylene glycol and / or surfactant was measured using a thermogravimetric differential thermal analyzer (TG-DTA). 10±0.5 mg of the surfactant was weighed in an aluminum pan and recorded as (W 3 ) (read to the fourth decimal place), then put it into the heating device, and heat it from 25°C to 450°C at 10°C / min in an air flow of 100 ml / min to thermally decompose the surfactant. Read the mass (W) when it reaches 300°C 4 ) (read to the fourth decimal place) and the mass at 350°C (W 5 )(read to the 4th decimal place), calculate W 4 / W 3 ×100(%), and W 5 / W 3 × 100(%), and calculate the mass residual rate (%) at 300°C and the mass residual rate (%) at 350°C.

[0102] In the present invention, TG-DTA2000SA manufactured by Bruker Corporation was used as a measuring apparatus.

[0103] <Method for measuring the amount of functional groups on the surface of carbon fiber bundles>

[0104] In this example, the surface oxygen concentration of the carbon fiber bundle was measured by X-ray photoelectron spectroscopy according to the following steps. First, the carbon fiber bundle was cut into 20 mm pieces, spread out and arranged on a copper sample support, and then AlKα was used as an X-ray source. 1、2 , keep the sample chamber at 1×10 -8 Torr, the photoelectron escape angle was set to 45°, and X-ray photoelectron spectroscopy was performed. It should be noted that as a correction value for the peak associated with charging during measurement, C 1S The binding energy value of the main peak of was adjusted to 285 eV. C was obtained by drawing a linear baseline in the range of 275 to 290 eV. 1S The peak area was taken as the binding energy value. The O 1s The peak area was defined as the binding energy. As an X-ray photoelectron spectroscopy apparatus, ESCA-1600 manufactured by ULVAC-PHI Co., Ltd. was used.

[0105] <Measurement method of CF friction fuzzing>

[0106] Two metal rods (material: stainless steel SUS304) with a diameter of 50 mm and a surface roughness Rmax of 0.3 μm were arranged in the vertical direction at an interval of 150 mm, and the carbon fiber bundle was in contact with and passed through the metal rods at a total angle of 0.785π (rad). Then, the carbon fiber bundle was mounted on the metal rod, and the unwinding tension from the package was set to 800 g. The carbon fiber bundle was pulled by a driving roller at a speed of 6 m per minute to pass through the metal rod. The fiber yarn after passing through the second metal rod was irradiated with laser light from the side at a right angle, and the number of fluffs was counted for 5 minutes using a fluff detection device, and the number was recorded.

[0107] In the present invention, the preferred range of operability was evaluated in three levels according to the following criteria, with S and A being considered acceptable and B being considered unacceptable.

[0108] S: less than 15 hairs / m

[0109] A: 15 or more hairs / m2, less than 25 hairs / m2

[0110] B: More than 25 hairs / m.

[0111] <Measurement method of dry FF friction coefficient>

[0112] On a bobbin fixed in a non-rotating manner, a thickness of 5 to 10 mm and a winding density of 0.9 to 1.4 g / cm2 are formed so as to make the thickness uniform. 3The surface of the carbon fiber bundle coated with the sizing agent is wound in a range, and the carbon fiber bundle identical to the roll is wound at intervals of 3 to 5 mm in the width direction in a manner such that the contact angle becomes 3π (rad) and does not overlap with itself. A weight (T1 = 0.25 g / tex) is applied to one end of the wound carbon fiber bundle, and the opposite end is stretched at a speed of 1 m / min using a spring balance. The tension when the wound carbon fiber bundle starts to move is set to T2, and the dry FF friction coefficient is calculated according to the following formula. Two measurements are performed, and the average value is taken as the dry FF friction coefficient. It should be noted that the measurement reel uses a reel that has been placed under the measurement atmosphere temperature and humidity conditions (measurement conditions: 23±3°C / 60±5%) before the measurement for more than 2 hours.

[0113] Dry FF friction coefficient = ln(T2 / T1) / θ

[0114] T2: Tension when the carbon fiber bundle starts to move (= indication value of the spring scale)

[0115] T1: weight (=0.25g / tex)

[0116] θ: the total contact angle of the roll and the wound filament (=3πrad).

[0117] <Wet FM Friction Coefficient Measurement Method>

[0118] A 50 mm stainless steel SUS304 rod is fixed in a manner parallel to the ground and does not rotate. The carbon fiber bundle coated with the sizing agent is cut from the bobbin and immersed in pure water for 1 second. Then, on the fixed rod, the thickness is uniform, the width is 1 to 3 mm, the contact angle is 3π (rad), and it does not overlap with itself, typically at intervals of 3 to 5 mm in the width direction. A weight (T3 = 0.25 g / tex) is applied to one end of the wound carbon fiber bundle, and the opposite end is stretched at a speed of 1 m / min with a spring balance. The tension when the wound carbon fiber bundle starts to move is set to T4, and the wet fiber-stainless steel SUS304 friction coefficient is calculated according to the following formula. Two measurements are performed, and the average value is used as the wet FM friction coefficient.

[0119] Wet FM friction coefficient = ln(T4 / T3) / θ

[0120] T4: Tension when the carbon fiber bundle starts to move (= indication value of the spring scale)

[0121] T3: weight (=0.25g / tex)

[0122] θ: the total contact angle of the roll and the wound filament (=3πrad).

[0123] <Carbon fiber bundle strength and bundle elastic modulus>

[0124] The strand strength and strand elastic modulus of the carbon fiber bundle are determined according to the resin impregnation strand test method of JIS R7608 (2004) and the following steps. Where the carbon fiber bundle is twisted, the evaluation is performed after untwisting by imparting a reverse twist equal to the number of twists. As the resin formulation, "Celloxide (registered trademark)" 2021P (manufactured by Daicel Chemical Industries, Ltd.) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by mass) is used, and as the curing conditions, normal pressure, temperature of 125°C, and time of 30 minutes are used. The strands of 10 carbon fiber bundles are measured, and the average values ​​are used as the strand strength and strand elastic modulus. It should be noted that the strain range when calculating the strand elastic modulus is 0.1 to 0.6%.

[0125] <Measurement method of interface shear strength>

[0126] The monofilaments were pulled out from the carbon fiber bundle, sandwiched from the top and bottom by a resin film laminated in a manner of 0.4 mm or more in thickness, heated and pressed by a hot press device, and then cooled to room temperature while maintaining the pressurized state to obtain a molded plate with the carbon fiber monofilaments embedded. A dumbbell-shaped IFSS test piece was punched out from the molded plate using an SD-type bar cutter.

[0127] Clamp the two ends of the dumbbell-shaped sample, apply tensile force along the fiber axis (length direction), and generate 12% strain at a rate of 2.0 mm / min. Then, cut 20 mm of the central part of the test piece and heat it to above the melting point of the thermoplastic resin in a state clamped between glass plates on a hot plate. Observe the length of the fragmented fibers inside the sample that has become transparent due to heating under a microscope. Furthermore, the critical fiber length lc is calculated based on the average broken fiber length la and the formula of lc (μm) = (4 / 3) × la (μm). The tensile strength σ of the wire bundle and the diameter d of the carbon fiber monofilament are measured, and the interface shear strength (IFSS), an indicator of the bonding strength of the interface between the carbon fiber and the resin, is calculated by the following formula. In the embodiment, the average value of the number of measurements n = 5 is taken as the test result.

[0128] IFSS(MPa)=σ(MPa)×d(μm) / (2×lc)(μm).

[0129] In the present invention, the preferred range of IFSS was evaluated in three levels according to the following criteria for each resin, and A was regarded as passing.

[0130] Resin: Polyetheretherketone

[0131] A: IFSS is 38 or above

[0132] B: IFSS is 35 or above and less than 38

[0133] C: IFSS less than 35.

[0134] The materials and components used in each example and each comparative example are as follows.

[0135] (A) Ingredients: Polyethylene glycol and / or nonionic surfactant

[0136] A-1: PEG distearate

[0137] ("IONET (registered trademark)" DS4000 manufactured by Sanyo Chemical Industries, Ltd., HLB: 16.6)

[0138] A-2: PEG monostearate

[0139] ("IONET (registered trademark)" MS1000 manufactured by Sanyo Chemical Industries, Ltd., HLB: 15.7)

[0140] A-3: PEG monooleate

[0141] ("IONET (registered trademark)" MO600 manufactured by Sanyo Chemical Industries, Ltd., HLB: 13.8)

[0142] A-4: PEG monooleate

[0143] ("IONET (registered trademark)" MO400 manufactured by Sanyo Chemical Industries, Ltd., HLB: 11.7)

[0144] A-5: PEG dioleate

[0145] ("IONET (registered trademark)" DO1000 manufactured by Sanyo Chemical Industries, Ltd., HLB: 12.9)

[0146] A-6: PEG dioleate

[0147] ("IONET (registered trademark)" DO600 manufactured by Sanyo Chemical Industries, Ltd., HLB: 10.5)

[0148] A-7: Polyethylene glycol

[0149] (PEG600 manufactured by Sanyo Chemical Industries, Ltd., HLB: 20, molecular weight: 600)

[0150] A-8: Polyethylene glycol

[0151] (PEG4000 manufactured by Sanyo Chemical Industries, Ltd., HLB: 20, molecular weight: 4000)

[0152] A-9: Polyethylene glycol

[0153] (PEG20000 manufactured by Sanyo Chemical Industries, Ltd., HLB: 20, molecular weight: 20000)

[0154] (B) Ingredient: Anionic surfactant

[0155] B-1: Sodium bis(2-ethylhexyl)sulfosuccinate

[0156] (Tokyo Chemical Industry Co., Ltd.)

[0157] B-2: Butyl Oleate Sulfated Oil

[0158] (Lion Corporation "LOTAT (registered trademark)" OH-104K, reaction rate: 79%)

[0159] B-3: Sodium alkylnaphthalene sulfonate

[0160] (Tokyo Chemical Industry Co., Ltd.)

[0161] B-4: Sodium dodecylbenzene sulfonate

[0162] (NEOPELEX (registered trademark) G15 manufactured by Kao Corporation)

[0163] B-5: Sodium Lauryl Sulfate

[0164] (Kao Corporation "EMAL (registered trademark)" 10G)

[0165] B-6: Disodium lauryl sulfosuccinate

[0166] ("BEAULIGHT (registered trademark)" SSS manufactured by Sanyo Chemical Industries, Ltd.)

[0167] B-7: Sodium 2-ethylhexyl sulfate

[0168] ("SANDET (registered trademark)" ONA manufactured by Sanyo Chemical Industries, Ltd.).

[0169] (C) Ingredient: Amphoteric Surfactant

[0170] C-1: Lauryl dimethylaminoacetic acid betaine

[0171] (Kao Corporation "Amphitol (registered trademark) 24B")

[0172] C-2: 2-Alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine

[0173] (Kao Corporation "Amphitol (registered trademark) 20Y-B")

[0174] C-3: N,N-dimethyldecylamine oxide

[0175] ("CADENAX (registered trademark) DM10D-W" manufactured by Lion Specialty Chemicals Co., Ltd.)

[0176] C-4: Lauryl dimethyl amine oxide

[0177] ("CADENAX (registered trademark) DM12D-W (C)" manufactured by Lion Specialty Chemicals Co., Ltd.)

[0178] C-5: N,N-dimethyl myristylamine oxide

[0179] ("CADENAX (registered trademark) DM14D-N" manufactured by Lion Specialty Chemicals Co., Ltd.)

[0180] C-6: Octadecyl dimethylaminoacetic acid betaine

[0181] (Kao Corporation "Amphitol (registered trademark) 86B")

[0182] (D) Alcohol and diol components

[0183] D-1: Propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0184] D-2: 2-Propanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0185] (E) Ingredients: Other ingredients

[0186] E-1: Polyvinyl alcohol

[0187] (PVA manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. (degree of polymerization: about 500)).

[0188] E-2: Diglycerol polyglycidyl ether

[0189] (Nagase ChemteX Co., Ltd. "Denacol (registered trademark)" Ex-421)

[0190] E-3: Polyethyleneimine

[0191] ("Lupasol (registered trademark)" G20 Waterfree manufactured by BASF Japan Co., Ltd.).

[0192] (F) Ingredient: Thermoplastic resin

[0193] F-1: Polyetheretherketone

[0194] (VICTREX (registered trademark) 450G manufactured by VICTREX Corporation).

[0195] This embodiment includes the following 1st to 5th steps.

[0196] · Step 1: Step of manufacturing carbon fiber bundle as raw material

[0197] The acrylonitrile copolymer was spun and calcined to obtain a carbon fiber bundle with a total number of 12,000 filaments and a total fineness of 800 tex. The strand strength and strand elastic modulus of the carbon fiber bundle were evaluated and were 5.1 GPa and 240 GPa, respectively. Next, the carbon fiber bundle was subjected to electrolytic surface treatment using an aqueous solution of ammonium bicarbonate as an electrolyte and an amount of 80 coulombs per 1 g of the carbon fiber bundle. Next, the carbon fiber bundle subjected to the electrolytic surface treatment was washed with water and dried in heated air to obtain a carbon fiber bundle as a raw material. The surface oxygen concentration of the carbon fiber bundle obtained in the first step was measured.

[0198] · Second step: Step of attaching a sizing agent to the carbon fiber bundle

[0199] (A-1) as compound (A) is made to have the composition of Table 1, water is added to obtain a uniformly dissolved aqueous solution of about 0.8% by mass. Using this aqueous solution as a sizing agent aqueous solution, the sizing agent is applied to the surface-treated carbon fiber bundle by an immersion method, and then, as a pre-drying process, heat-treated at a temperature of 120°C for 15 seconds with a hot roller, and then, as a second drying process, heat-treated in heated air at a temperature of 210°C for 60 seconds to obtain a carbon fiber bundle coated with a sizing agent. The amount of sizing agent attached is adjusted to 0.25 parts by mass relative to the total amount of 100 parts by mass of the surface-treated carbon fiber bundle coated with the sizing agent. In addition, the mass residual rate of the sizing agent applied in the second process is measured. The mass residual rate at 300°C is 3%, and the mass residual rate at 350°C is 1%, which shows that it is fully thermally decomposed.

[0200] · Step 3: Evaluation of the operability of the carbon fiber bundle coated with the sizing agent

[0201] The carbon fiber bundle coated with the sizing agent obtained in the second step was used to evaluate the workability based on the friction coefficient evaluation method and the CF friction fuzzing measurement method. As a result, the dry FF friction coefficient was 0.22 and the wet FM friction coefficient was 0.22, which shows that in the processing step where the rod exists in the air and water, fuzz is not easily generated and the workability is sufficiently good.

[0202] · Step 4: Evaluation of the amount of sizing agent adhered after washing

[0203] For the carbon fiber bundle coated with the sizing agent obtained in the above process, as described in the above-mentioned <Calculation method of the amount of sizing agent attached after 50 seconds of water washing> and <Calculation method of the amount of sizing agent attached after 25 seconds of water washing>, the carbon fiber bundle coated with the sizing agent is washed with water to obtain the carbon fiber bundle coated with the sizing agent after 50 seconds of water washing and after 25 seconds of water washing, and then the amount of sizing agent attached after 50 seconds of water washing and the amount of sizing agent attached after 25 seconds of water washing are calculated. As a result, when the amount of sizing agent attached after 50 seconds of water washing is 0.10 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, and the amount of sizing agent attached after 25 seconds of water washing is 0.11 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, in any case, the residual amount is small and the solubility is sufficiently high.

[0204] ・Step 5: Preparation and evaluation of test pieces for IFSS measurement

[0205] Using the washed carbon fiber bundle coated with the sizing agent obtained in the above step and (F-1) as the thermoplastic resin (F), a test piece for IFSS measurement was prepared based on the method for measuring interfacial shear strength.

[0206] Next, the IFSS was measured using the obtained IFSS measurement test piece. As a result, the IFSS was 38 MPa when the carbon fiber bundle coated with the sizing agent after washing for 50 seconds was used, and the IFSS was 38 MPa when the carbon fiber bundle coated with the sizing agent after washing for 25 seconds was used, and the adhesion was sufficiently high in either case. The above results are summarized in Table 1.

[0207] [Table 1]

[0208]

[0209] (Example 2)

[0210] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent in the second step was changed as shown in Table 1, and various evaluations were performed. As shown in Table 1, it was found that the workability was good and the dissolution property was sufficiently high.

[0211] (Examples 3 to 5)

[0212] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1, except that the composition of the sizing agent and the amount of sizing agent applied in the second step were changed as shown in Table 1, and various evaluations were performed. As shown in Table 1, it was found that the workability was good and the dissolution property was sufficiently high.

[0213] (Comparative Example 1)

[0214] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent and the amount of sizing agent adhered in the second step were changed as shown in Table 1, and various evaluations were performed. As shown in Table 1, the workability was good, but the amount of sizing agent adhered was high and the solubility was insufficient.

[0215] (Comparative Example 2)

[0216] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1, except that the composition of the sizing agent and the amount of sizing agent applied in the second step were changed as shown in Table 1, and various evaluations were performed. As shown in Table 1, the dry FF friction coefficient was high and the workability was insufficient.

[0217] (Comparative Examples 3 to 5)

[0218] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent in the second step was changed as shown in Table 1, and various evaluations were performed. As shown in Table 1, the workability was good, but the HLB was low, the terminal hydroxyl ratio was low, and the solubility was insufficient.

[0219] (Example 6)

[0220] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent in the second step was changed as shown in Table 2, and various evaluations were performed. As shown in Table 2, it was found that the workability was good and the dissolution property was sufficiently high.

[0221] [Table 2]

[0222]

[0223] (Example 7)

[0224] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 1, except that the surface treatment amount in the first step was changed to 40 coulomb / g and the composition of the sizing agent in the second step was changed as shown in Table 1. Various evaluations were performed. The results are summarized in Table 2, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0225] (Examples 8 and 9)

[0226] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent and the amount of sizing agent applied in the second step were changed as shown in Table 2, and various evaluations were performed. As shown in Table 2, it was found that the workability was good and the dissolution property was sufficiently high.

[0227] (Comparative Example 6)

[0228] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent and the amount of sizing agent applied in the second step were changed as shown in Table 2, and various evaluations were performed. As shown in Table 2, the dry FF friction coefficient was high and the workability was insufficient.

[0229] (Examples 10 and 11)

[0230] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent in the second step was changed as shown in Table 2, and various evaluations were performed. As shown in Table 2, it was found that the workability was good and the dissolution property was sufficiently high.

[0231] (Comparative Example 7)

[0232] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent and the amount of sizing agent attached in the second step were changed as shown in Table 2, and various evaluations were performed. As shown in Table 2, the workability was good, but the hydrophilicity was insufficient and the dissolution was insufficient.

[0233] (Example 12)

[0234] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1 except that the composition of the sizing agent and the amount of sizing agent applied in the second step were changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 3, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0235] [Table 3]

[0236]

[0237] (Example 13)

[0238] In the second step, the drying temperature of the second drying step was changed to 150° C., and the same operation as in Example 12 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. The results are shown in Table 3, and it was found that the handleability was good and the dissolution property was sufficiently high.

[0239] (Comparative Example 8)

[0240] In the second step, the drying temperature of the second drying step was changed to 80° C., and the same operation as in Example 12 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 3, the dissolution property was sufficiently high, but the dry FF friction coefficient was high and the workability was insufficient.

[0241] (Comparative Example 9)

[0242] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12 except that the amount of sizing agent applied in the second step was changed as shown in Table 3, and various evaluations were performed. As shown in Table 3, the dissolution property was sufficiently high, but the dry FF friction coefficient was high and the workability was insufficient.

[0243] (Example 14)

[0244] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 12 except that the amount of sizing agent applied in the second step was changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 3, and it was found that the workability was good and the dissolution property was sufficiently high.

[0245] (Example 15)

[0246] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12 except that the surface treatment amount in the first step was changed to 40 coulomb / g and the adhesion amount of the sizing agent in the second step was changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 3, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0247] (Comparative Example 10)

[0248] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 12 except that the composition and adhesion amount of the sizing agent in the second step were changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 1, and the workability is good, but the ratio of the hydrophilic group of the anion in the anionic surfactant is low, and the solubility is insufficient.

[0249] (Examples 16 to 18)

[0250] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 12 except that the composition and adhesion amount of the sizing agent in the second step were changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 3, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0251] (Examples 19 to 22)

[0252] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 12 except that the composition and adhesion amount of the sizing agent in the second step were changed as shown in Table 3, and various evaluations were performed. The results are summarized in Table 4, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0253] [Table 4]

[0254]

[0255] (Example 23)

[0256] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12, except that the amount of the sizing agent in the second step was changed as shown in Table 4, and (D-1) as the second component was added at a ratio relative to the total amount of the sizing agent as shown in Table 4, and various evaluations were performed. The results are summarized in Table 4, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0257] (Example 24)

[0258] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12, except that the amount of the sizing agent in the second step was changed as shown in Table 4, and (D-2) as the second component was added at a ratio relative to the total amount of the sizing agent as shown in Table 4, and various evaluations were performed. The results are summarized in Table 4, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0259] (Example 25)

[0260] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12 except that the amount of the sizing agent in the second step was changed as shown in Table 4 and (E-2) as the second component was added at a ratio relative to the total amount of the sizing agent as shown in Table 4, and various evaluations were performed. The results are summarized in Table 4, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0261] (Example 26)

[0262] The carbon fiber bundle coated with the sizing agent was obtained in the same manner as in Example 12 except that the amount of adhesion in the second step was changed as shown in Table 4 and (E-3) as the second component was added at a ratio relative to the total amount of the sizing agent as shown in Table 4, and various evaluations were performed. The results are summarized in Table 4, and it can be seen that the workability is good and the dissolution is sufficiently high.

[0263] (Example 27)

[0264] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 1, except that the amount of sizing agent applied in the second step was changed as shown in Table 5, and various evaluations were performed. As shown in Table 5, it was found that the workability was good and the dissolution property was sufficiently high.

[0265] [Table 5]

[0266]

[0267] (Examples 28 and 29)

[0268] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 27 except that the amount of sizing agent applied in the second step was changed as shown in Table 5, and various evaluations were performed. As shown in Table 5, it was found that the workability was good and the dissolution property was sufficiently high.

[0269] (Examples 30 and 31)

[0270] In the second step, (C-2) was used as the compound (C), and the amount of sizing agent attached was changed as shown in Table 5. The same operation as in Example 27 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 5, it was found that the handleability was good and the dissolution property was sufficiently high.

[0271] (Example 32)

[0272] In the second step, (C-3) was used as the compound (C), the amount of sizing agent attached was changed as shown in Table 5, and as a pre-drying step, heat treatment was performed at 120°C for 15 seconds using a hot roller, and the second drying step was not used. The same operation as in Example 27 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 5, it can be seen that the workability is good and the solubility is also sufficiently high.

[0273] (Example 33)

[0274] In the second step, (C-4) was used as the compound (C), the amount of sizing agent attached was changed as shown in Table 5, and as a pre-drying step, heat treatment was performed at 120°C for 15 seconds using a hot roller, and the second drying step was not used. The same operation as in Example 27 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 5, it can be seen that the workability is good and the solubility is also sufficiently high.

[0275] (Example 34)

[0276] In the second step, (C-5) was used as the compound (C), the amount of sizing agent attached was changed as shown in Table 5, and as a pre-drying step, heat treatment was performed at 120°C for 15 seconds using a hot roller, and the second drying step was not used. The same operation as in Example 27 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 5, it can be seen that the workability is good and the solubility is also sufficiently high.

[0277] (Comparative Example 11)

[0278] A carbon fiber bundle coated with a sizing agent was obtained in the same manner as in Example 25 except that the amount of sizing agent applied in the second step was changed as shown in Table 5, and various evaluations were performed. As shown in Table 1, the dry FF friction coefficient was high and the workability was insufficient.

[0279] (Comparative Example 12)

[0280] A carbon fiber bundle coated with a sizing agent was obtained and various evaluations were performed in the same manner as in Example 25 except that the amount of sizing agent adhered in the second step was changed as shown in Table 5. The results are shown in Table 1, showing good workability, but high adhesion and insufficient solubility.

[0281] (Comparative Example 13)

[0282] In the second step, (C-2) was used as the compound (C) and the amount of sizing agent attached was changed as shown in Table 5. The same operation as in Example 25 was performed to obtain a carbon fiber bundle coated with a sizing agent, and various evaluations were performed. As shown in Table 5, the dry FF friction coefficient was high and the operability was insufficient.

[0283] (Comparative Example 14)

[0284] In the second step, (C-6) was used as the compound (C) and the amount of sizing agent attached was changed as shown in Table 5. The same operation as in Example 25 was carried out to obtain a carbon fiber bundle coated with a sizing agent and various evaluations were performed. As shown in Table 5, the alkyl group had a large number of carbon atoms and the solubility was insufficient.

[0285] Industrial Applicability

[0286] According to the present invention, a carbon fiber bundle coated with a sizing agent can be provided, wherein the carbon fiber bundle coated with a sizing agent exhibits good operability, and the sizing agent on the carbon fiber bundle exhibits good solubility in water during the water washing process, thereby reducing the mixing of the sizing agent into the matrix resin and stabilizing the physical properties. The thermoplastic resin composite using the present invention is lightweight and excellent in strength, and can therefore be suitably used in many fields such as aircraft parts, spacecraft parts, automobile parts, ship parts, civil engineering and construction materials, and sporting goods.

[0287] Description of Reference Numerals

[0288] 11: Rolling out process

[0289] 12: Washing process

[0290] 13: Drying process

[0291] 14: Winding process

[0292] 15: Free roller in front of washing tank

[0293] 16: Free roller in washing tank

[0294] 17: Free roller after washing tank

[0295] 18: Washing tank

[0296] 19: Free roller in front of washing tank

[0297] 20: Free roller in washing tank

[0298] 21: Free roller after washing tank

[0299] 22: Washing tank

[0300] 1a: Carbon fiber bundle coated with sizing agent

[0301] 1b: Carbon fiber bundle coated with sizing agent after washing

[0302] 1c: Carbon fiber bundle coated with sizing agent after washing and drying

[0303] 1d: water

[0304] 1e: water

Claims

1. A carbon fiber bundle coated with a sizing agent, wherein a sizing agent containing a surfactant is coated on the carbon fiber bundle, wherein the carbon fiber bundle coated with the sizing agent satisfies all of the following (i) to (iii), (i) the amount of the sizing agent applied is not less than 0.15 parts by mass and not more than 0.80 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent; (ii) Dry FF friction coefficient is less than 0.39; (iii) the amount of sizing agent attached after washing with water for 50 seconds is 0.12 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, The amount of sizing agent attached after washing for 50 seconds is measured by the following method: The carbon fiber bundle coated with the sizing agent is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the carbon fiber bundle is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the water is dried by continuously passing through the drying process, and the carbon fiber bundle is wound in the winding process. The water temperature is set to 25°C, the unwinding tension from the bobbin is set to 800g, the process speed is set to 2.4m / min, and the diameter of the free roller in the water washing tank is set to 150mm. The contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in a manner that the passing time in the water in one water washing tank is 25 seconds, and the total passing time in the two water washing tanks is 50 seconds. The washed carbon fiber bundle coated with the sizing agent is dried at a drying temperature of 150°C for 1 minute in a non-contact drying manner to obtain a washed and dried carbon fiber bundle coated with the sizing agent. The sizing agent adhesion amount of the washed and dried carbon fiber bundle coated with the sizing agent is measured to obtain the sizing agent adhesion amount. in, The surfactant comprises a nonionic surfactant, The nonionic surfactant satisfies any one of the following (vi) to (v), (vi) HLB is 15 or more but less than 20; (v) HLB is 12 or more and less than 15, and the ratio of hydroxyl groups at the molecular terminals is 50% or more.

2. A carbon fiber bundle coated with a sizing agent, wherein a sizing agent containing polyethylene glycol is coated on the carbon fiber bundle, wherein the carbon fiber bundle coated with the sizing agent satisfies all of the following (i) to (iii), (i) the amount of the sizing agent applied is not less than 0.15 parts by mass and not more than 0.80 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent; (ii) Dry FF friction coefficient is less than 0.39; (iii) the amount of the sizing agent attached after washing with water for 50 seconds is 0.12 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, The amount of sizing agent attached after washing for 50 seconds is measured in the following manner: The carbon fiber bundle coated with the sizing agent is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the carbon fiber bundle is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the water is dried by continuously passing through the drying process, and the carbon fiber bundle is wound in the winding process. The water temperature is set to 25°C, the unwinding tension from the bobbin is set to 800g, the process speed is set to 2.4m / min, and the diameter of the free roller in the water washing tank is set to 150mm. The contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in a manner that the passing time in the water in one water washing tank is 25 seconds, and the total passing time in the two water washing tanks is 50 seconds. The washed carbon fiber bundle coated with the sizing agent is dried at a drying temperature of 150°C for 1 minute in a non-contact drying manner to obtain a washed and dried carbon fiber bundle coated with the sizing agent. The sizing agent adhesion amount of the washed and dried carbon fiber bundle coated with the sizing agent is measured to obtain the sizing agent adhesion amount. in, The weight average molecular weight Mw of the polyethylene glycol is 300 or more and 5000 or less.

3. A carbon fiber bundle coated with a sizing agent, wherein a sizing agent comprising polyethylene glycol and a surfactant or a sizing agent comprising a surfactant is coated on the carbon fiber bundle, wherein the carbon fiber bundle coated with the sizing agent satisfies all of the following (i) to (iii), (i) the amount of the sizing agent applied is not less than 0.15 parts by mass and not more than 0.80 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent; (ii) Dry FF friction coefficient is less than 0.39; (iii) the amount of the sizing agent attached after washing with water for 50 seconds is 0.12 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, The amount of sizing agent attached after washing for 50 seconds is measured in the following manner: The carbon fiber bundle coated with the sizing agent is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the carbon fiber bundle is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the water is dried by continuously passing through the drying process, and the carbon fiber bundle is wound in the winding process. The water temperature is set to 25°C, the unwinding tension from the bobbin is set to 800g, the process speed is set to 2.4m / min, and the diameter of the free roller in the water washing tank is set to 150mm. The contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in a manner that the passing time in the water in one water washing tank is 25 seconds, and the total passing time in the two water washing tanks is 50 seconds. The washed carbon fiber bundle coated with the sizing agent is dried at a drying temperature of 150°C for 1 minute in a non-contact drying manner to obtain a washed and dried carbon fiber bundle coated with the sizing agent. The sizing agent adhesion amount of the washed and dried carbon fiber bundle coated with the sizing agent is measured to obtain the sizing agent adhesion amount. in, The surfactant comprises an anionic surfactant, The ratio of hydrophilic groups in anions constituting the anionic surfactant is 17% or more.

4. A carbon fiber bundle coated with a sizing agent, wherein a sizing agent comprising polyethylene glycol and a surfactant or a sizing agent comprising a surfactant is coated on the carbon fiber bundle, wherein the carbon fiber bundle coated with the sizing agent satisfies all of the following (i) to (iii), (i) the amount of the sizing agent applied is not less than 0.15 parts by mass and not more than 0.80 parts by mass relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent; (ii) Dry FF friction coefficient is less than 0.39; (iii) the amount of the sizing agent attached after washing with water for 50 seconds is 0.12 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent, The amount of sizing agent attached after washing for 50 seconds is measured in the following manner: The carbon fiber bundle coated with the sizing agent is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the carbon fiber bundle is passed through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank, and the free roller after the water washing tank. Then, the water is dried by continuously passing through the drying process, and the carbon fiber bundle is wound in the winding process. The water temperature is set to 25°C, the unwinding tension from the bobbin is set to 800g, the process speed is set to 2.4m / min, and the diameter of the free roller in the water washing tank is set to 150mm. The contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in a manner that the passing time in the water in one water washing tank is 25 seconds, and the total passing time in the two water washing tanks is 50 seconds. The washed carbon fiber bundle coated with the sizing agent is dried at a drying temperature of 150°C for 1 minute in a non-contact drying manner to obtain a washed and dried carbon fiber bundle coated with the sizing agent. The sizing agent adhesion amount of the washed and dried carbon fiber bundle coated with the sizing agent is measured to obtain the sizing agent adhesion amount. in, The total amount of the surfactants is 70 parts by mass or more based on 100 parts by mass of the total amount of the organic components in the sizing agent, and the amount of the amphoteric surfactant is 50 parts by mass or more of the total amount of the surfactants. 5 . The carbon fiber bundle coated with a sizing agent according to claim 1 , wherein the carbon fiber bundle has a wet FM friction coefficient of 0.28 or less.

6. The carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein The amount of sizing agent attached after washing with water for 25 seconds is 0.12 parts by mass or less relative to 100 parts by mass of the carbon fiber bundle coated with the sizing agent. The amount of sizing agent attached after washing for 25 seconds is measured in the following manner: The carbon fiber bundle coated with the sizing agent passes through the water in the water washing tank via the free roller before the water washing tank, the free roller in the water washing tank and the free roller after the water washing tank, and then continuously passes through the drying process to dry the water, and is wound in the winding process. The water temperature is set to 25°C, the unwinding tension from the bobbin is set to 800g, the process speed is set to 2.4m / min, the diameter of the free roller in the water washing tank is set to 150mm, and the contact angle between the carbon fiber bundle coated with the sizing agent and the free roller in the water washing tank is set to πrad. In addition, the liquid level is adjusted in such a way that the passing time in the water becomes 25 seconds. The carbon fiber bundle coated with the sizing agent after washing is dried in a non-contact drying method at a drying temperature of 150°C for 1 minute to obtain a carbon fiber bundle coated with the sizing agent after washing and drying. The sizing agent adhesion amount is obtained by measuring the sizing agent adhesion amount of the carbon fiber bundle coated with the sizing agent after washing and drying.

7. The carbon fiber bundle coated with a sizing agent according to claim 1 or 3, wherein: The total amount of the surfactant is 70 parts by mass or more based on 100 parts by mass of the total amount of the sizing agent.

8. The carbon fiber bundle coated with a sizing agent according to claim 1, wherein The total amount of the surfactant is 70 parts by mass or more based on 100 parts by mass of the total amount of the sizing agent, and the nonionic surfactant is 50 parts by mass or more of the total amount of the surfactant.

9. The carbon fiber bundle coated with a sizing agent according to claim 1, 3 or 4, wherein: The weight average molecular weight Mw of the surfactant is 150 or more and 5000 or less.

10. The carbon fiber bundle coated with a sizing agent according to claim 3, wherein: The total amount of the surfactant is 70 parts by mass or more based on 100 parts by mass of the total amount of the sizing agent, and the anionic surfactant is 50 parts by mass or more of the total amount of the surfactant.

11. The carbon fiber bundle coated with a sizing agent according to claim 1, wherein In addition to the surfactant, the present invention further comprises 0.1 to 30 parts by mass of an aliphatic or alicyclic compound having one hydroxyl group bonded to carbon and / or an aliphatic or alicyclic compound having two hydroxyl groups bonded to two different carbons, based on 100 parts by mass of the total amount of the sizing agent.

12. The carbon fiber bundle coated with a sizing agent according to claim 2, wherein: In addition to the polyethylene glycol, an aliphatic or alicyclic compound having one hydroxyl group bonded to carbon and / or an aliphatic or alicyclic compound having two hydroxyl groups bonded to two different carbons is contained in an amount of 0.1 to 30 parts by mass based on 100 parts by mass of the total amount of the sizing agent.

13. The carbon fiber bundle coated with a sizing agent according to claim 3 or 4, wherein: In addition to the polyethylene glycol and / or surfactant, the present invention also contains 0.1 to 30 parts by mass of an aliphatic or alicyclic compound in which one hydroxyl group is bonded to carbon, and / or an aliphatic or alicyclic compound in which two hydroxyl groups are bonded to two different carbons, based on 100 parts by mass of the total amount of the sizing agent.

14. The carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein The amount of the sizing agent attached after the water washing for 50 seconds is 0.08 parts by mass or less based on 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

15. The carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein The amount of the sizing agent applied is 0.25 to 0.45 parts by mass based on 100 parts by mass of the carbon fiber bundle coated with the sizing agent.

16. The carbon fiber bundle coated with a sizing agent according to claim 4, wherein: The average number of carbon atoms of the alkyl group constituting the amphoteric surfactant is 17 or less.

17. The carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein The absorbance of the extract obtained by extracting the carbon fiber bundle with distilled water for 1 minute at 600 nm was 0.06 or more.

18. The carbon fiber bundle coated with a sizing agent according to claim 1, wherein When the temperature of the surfactant was increased at 10° C. / min in air, the mass residual rate at 300° C. was 35% or less.

19. The carbon fiber bundle coated with a sizing agent according to claim 2, wherein: When the temperature of polyethylene glycol was increased at 10° C. / min in air, the mass residual rate at 300° C. was 35% or less.

20. The carbon fiber bundle coated with a sizing agent according to claim 3 or 4, wherein: When the temperature of polyethylene glycol and / or surfactant is increased at 10°C / min in air, the mass residual rate at 300°C is 35% or less.

21. The carbon fiber bundle coated with a sizing agent according to claim 1, wherein When the temperature of the surfactant was increased at 10°C / min in air, the mass residual rate at 350°C was 30% or less.

22. The carbon fiber bundle coated with a sizing agent according to claim 2, wherein: When the temperature of polyethylene glycol was increased at 10° C. / min in air, the mass residual rate at 350° C. was 30% or less.

23. The carbon fiber bundle coated with a sizing agent according to claim 3 or 4, wherein: When the temperature of polyethylene glycol and / or a surfactant is increased at 10°C / min in air, the mass residual rate at 350°C is 30% or less.

24. The carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein The strand strength of the carbon fiber bundle is 4.0 GPa or more.

25. A method for producing a carbon fiber bundle coated with a sizing agent, which is the method for producing a carbon fiber bundle coated with a sizing agent according to any one of claims 1 to 4, wherein the method comprises a drying step of drying the carbon fiber bundle coated with the sizing agent at 120 to 260° C. after a step of applying a sizing agent containing polyethylene glycol and / or a surfactant to the carbon fiber bundle.

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