TW201908565A - Method for producing carbon fiber bundle with sizing agent - Google Patents

Abstract

A method for manufacturing carbon fiber bundles with a sizing agent applied, in which after a sizing application step in which a plurality of carbon fiber bundles are immersed in parallel in a sizing agent liquid tank, the carbon fiber bundles pass through a drying step to yield the carbon fiber bundles with sizing agent applied, wherein, in order to resolve the problem of winding sticking due to adhesion of the sizing agent liquid to a guide roller, the carbon fiber bundles are immersed in the sizing agent liquid tank, and the guide roller surface stickiness of the initial guide roller after the carbon fiber bundles leave the liquid surface of the sizing agent liquid tank is set at 0.2 N/cm2 or less.

Description

Manufacturing method of carbon fiber bundle provided with sizing agent

The present invention relates to a method for producing a sizing agent-added carbon fiber bundle.

Carbon fiber bundles are characterized by excellent mechanical properties, especially high specific strength and high specific elasticity. Therefore, carbon fiber bundles are widely used in aerospace × space applications, sports and leisure applications, and general industrial applications such as automobiles and windmills. In recent years, there has been a strong demand from users who use carbon fiber bundles for quality improvement and cost reduction.

Carbon fiber bundles generally have low elongation and brittleness. In high-order processing steps, fluff is easily generated due to contact with a roller or rubbing with a wire guide, and broken wires may occur. Therefore, generally, various sizing agents are added to the carbon fiber bundles to improve the operability, improve the convergence or rub resistance of the carbon fiber bundles, or suppress the fluff generation of the carbon fiber bundles to maintain the quality.

As a method for applying a sizing agent to a carbon fiber bundle, there are various methods such as a spray spray method, a dropping method, and a kiss roller method. An immersion method in which a carbon fiber bundle is immersed in a sizing agent tank is preferable in terms of efficiency that can be simultaneously and easily imparted to a multifilament. However, when multi-filamentization of a carbon fiber bundle or high-speed production is achieved in order to reduce cost, the amount of sizing agent liquid adhering to a carbon fiber bundle and taken out from a sizing agent tank increases, and The amount of the sizing agent liquid introduced into the guide roller of the drying step subsequent to the sizing agent applying step also increased. Then, on the surface of the guide roller, the sizing agent liquid is dried to cause resin accumulation, and the viscosity is increased. When the carbon fiber bundle is brought into contact with the resin accumulation, there is a problem that fluff is generated, and the carbon fiber bundle may be wound around the guide roller, and the step passability may be reduced. In addition, in order to achieve multi-filament, the interval between adjacent carbon fiber bundles is narrowed. In this case, a film made of a sizing solution is easily generated between the adjacent filaments. In addition, the liquid film is directly dried to cause adhesion spots of the sizing agent liquid. In addition, there is also a problem that the carbon fiber bundles adjoining each other adhering to each other due to the surface tension of the sizing solution are liable to cause poor weaving.

As an improvement technique, Patent Documents 1 and 2 disclose a method in which a carbon fiber bundle is taken out of the liquid surface of a sizing agent tank, and then a pressurized gas is sprayed toward the carbon fiber bundle, whereby the yarn of the carbon fiber bundle is discharged. The sizing agent-containing liquid film is removed in between.

Patent Document 3 discloses a method of removing the remaining sizing solution impregnated with the carbon fiber bundle by holding the carbon fiber bundle with at least one pair of nip rollers, and applying the sizing agent to the surface of the nip roller, thereby Prevent drying of the sizing solution. In addition, Patent Document 4 discloses a method for pressing a wiping cloth against a carbon fiber bundle with excellent openability after sizing treatment of a carbon fiber bundle in an untwisted state and drying with a heat roller. Heat the roller to remove the remaining sizing solution from the heat roller. [Prior Art Literature] [Patent Literature]

[Patent Literature 1] Japanese Patent Laid-Open No. 2013-23785 [Patent Literature 2] Japanese Patent Laid-Open No. 7-145549 [Patent Literature 3] Japanese Patent Laid-Open No. 2011-256486 [Patent Literature 4] Japanese Patent Special Kaiping No. 1-292038

[Problems to be Solved by the Invention] However, the methods of Patent Documents 1 and 2 have the following problems: even if the liquid film between the carbon fiber bundle filaments is removed, the sizing agent liquid still adheres to the carbon fiber bundle and the sizing agent Liquid is transferred onto the surface of the guide roller to cause resin accumulation. In addition, the method of Patent Document 3 has a problem in that the brittle carbon fiber bundle is held by a nip roller, so that fluff is generated and the step passability is reduced. The method of Patent Document 4 has a problem in that the excess sizing agent liquid adhered to the heat roller is removed with a wiping cloth, so resin accumulation due to drying of the sizing agent liquid on the heat roller itself is suppressed, However, on the first guide roller before the sizing agent applying step before the heat roller, the sizing agent liquid is easily dried, and the monofilament of the carbon fiber bundle is taken into the resin generated during the drying of the sizing agent solution. Rising or tangling.

An object of the present invention is to solve the problems of the prior art, and to provide a method for producing a carbon fiber bundle provided with a sizing agent. In the method for producing a carbon fiber bundle provided with a sizing agent solution, the problem can be solved. Drying of the sizing solution on the guide rollers × the problem of entanglement or fluffing of the carbon fiber bundle due to resin accumulation. [Means for solving problems]

To achieve the above object, the present invention has the following configuration. That is, a method for producing a sizing agent-provided carbon fiber bundle is obtained by sizing a plurality of carbon fiber bundles in parallel in a sizing agent application step and then drying the step to obtain a sizing agent application. In the method for producing a carbon fiber bundle provided with a sizing agent, the carbon fiber bundle is immersed in a sizing agent tank, and the first carbon fiber bundle is taken out from the liquid surface of the sizing agent tank. The guide roller surface tackiness of the guide roller is set to 0.2 N / cm ² or less. [Effect of the invention]

According to the present invention, in the method for producing a sizing agent-added carbon fiber bundle to which a sizing agent liquid is given, drying of the sizing agent liquid on the guide roller is prevented and resin accumulation is prevented, thereby obtaining a high-quality, low-fluff Carbon fiber bundle. In addition, the entanglement of the carbon fiber bundle to the guide roller can be suppressed, and the step passability is also excellent.

The method for producing a sizing agent-provided carbon fiber bundle according to the present invention is a sizing agent-imparting carbon fiber bundle provided through a sizing agent-imparting step and a drying step provided thereafter. A plurality of parallel carbon fiber bundles are immersed in the sizing agent tank. At this time, the carbon fiber bundles are immersed in the sizing agent tank, and the first guide roller after taking out the carbon fiber bundles from the liquid surface of the sizing agent tank The surface adhesiveness of the guide roller is set to 0.2 N / cm ² or less.

Hereinafter, the method of manufacturing the carbon fiber bundle provided with the sizing agent of this invention is demonstrated in detail.

The carbon fiber bundle used in the present invention can be obtained from any raw materials such as pitch-based, fluorene-based, and polyacrylonitrile-based materials. From the viewpoint of quality and productivity, polyacrylonitrile-based carbon fiber bundles are preferred. The form of the carbon fiber bundle used in the present invention is not particularly limited, and for example, a bundle of carbon fibers having a monofilament diameter of 3 μm or more and 10 μm or less can be used. In addition, the number of monofilaments of the carbon fibers constituting the carbon fiber bundle is not particularly limited, and may be, for example, 1,000 to 100,000. Among them, when a large amount of the sizing agent liquid is taken out of the sizing agent liquid tank, and the number of monofilaments is relatively large, the number of the carbon fiber bundles is 3,000 or more. The effect of the present invention is easily effective.

In the present invention, the polyacrylonitrile-based carbon fiber bundle that can be preferably used can be obtained by flame-retarding, pre-carbonizing, and carbonizing the polyacrylonitrile-based precursor fiber bundle by a known method, and is not particularly limited. Refractory can be carried out in an oxidizing environment at 200 ° C to 300 ° C. As the oxidizing gas under refractory, air is preferable from the economic viewpoint. Then, pre-carbonization can be performed in a pre-carbonization furnace in an inert environment and at a maximum temperature of 300 ° C to 1000 ° C. Further, the pre-carbonized fiber bundle was carbonized at a maximum temperature of 1200 ° C to 2000 ° C, thereby obtaining a carbon fiber bundle. The carbon fiber bundle may be graphitized at a temperature of 2000 ° C. to 3000 ° C. if necessary. The pre-carbonization, carbonization and graphitization are performed in an inert environment. As the inert gas used, for example, nitrogen, argon, and xenon are used. From the economic point of view, nitrogen can be preferably used.

In addition, when forming a carbon fiber reinforced composite material, in order to easily improve the affinity or adhesion between the carbon fiber bundle and the matrix resin, the carbon fiber bundle is preferably subjected to electrolytic oxidation treatment in an electrolytic solution or oxidation treatment in a gas phase or a liquid phase. Surface treatment. As the electrolytic solution, either an acidic aqueous solution or an alkaline aqueous solution can be used. As the acidic aqueous solution, sulfuric acid or nitric acid exhibiting strong acidity is preferred, and as the alkaline aqueous solution, ammonium carbonate or ammonium bicarbonate can be preferably used. Or an aqueous solution of an inorganic base such as ammonium bicarbonate.

As the sizing agent liquid used in the present invention, those obtained by dispersing or dissolving a sizing agent in an organic solvent such as water or acetone can be used. From the viewpoint of uniformly imparting carbon fiber bundles and safety, it is preferable. An aqueous dispersion or aqueous solution prepared by dispersing or dissolving a sizing agent in water. In addition, the sizing agent can be used from those known in the field of carbon fibers based on a matrix resin used in high-order processing. The sizing agent may include a base agent described later and various additives, and may include, for example, a base agent and an emulsifier. By drying the carbon fiber bundle impregnated with the sizing agent liquid, a sizing agent-added carbon fiber bundle having a sizing agent adhered to the surface of the carbon fiber bundle can be obtained.

The type of the sizing agent used in the present invention is not particularly limited, and the present invention is effective for a sizing agent liquid that is easy to be dried on a guide roller to cause resin to accumulate and form an adhesive deposit. When the thermosetting resin is included in the sizing agent, epoxy resin, epoxy modified polyurethane resin, polyester resin, phenol resin, and polyfluorene can be used as the main component of the sizing agent. Amine resin, polyurethane resin, polycarbonate resin, polyetherimide resin, polyimide resin, polyimide resin, bismaleimide resin, urethane Modified epoxy resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, polyether fluorene resins, etc., or two or more of these resins may be used in combination. When the sizing agent contains a thermoplastic resin, as the main component of the sizing agent, a material selected from the group consisting of polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and poly Vinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, polypropyleneimine, polyphenylene ether, polyacetal, polybutylene terephthalate, polyphenylene sulfide, polyetheretherketone Elastomer cellulose compounds, acrylic resins, polyurethane resins, polyamide resins, fluororesins, Acrylonitrile Butadiene Styrene (ABS) resins and liquid crystal polymers, styrene -At least one or more components of the group of sodium hydroxide (partial) neutralizers of the maleic anhydride copolymer.

In addition, since most of these organic compounds are insoluble in water, a surfactant may be added to form a latex. The type of the surfactant is not particularly limited, but a nonionic surfactant is preferably used. Examples of non-ionic surfactants include polyoxyethylene alkyl ethers, single linear polyoxyethylene alkyl ethers, polyoxyethylene secondary alcohol ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene sterol ethers, Polyoxyethylene sterol ethers, polyoxyethylene lanolin derivatives, ethylene oxide derivatives of alkylphenol formaldehyde condensates, polyoxyethylene polyoxypropylene alkyl ethers and other ether types, polyoxyethylene glyceryl fatty acid esters, polyoxyethylene Ether types such as ethylene castor oil and hardened castor oil, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyethylene glycol fatty acid esters, polyglycerol fatty acid esters, etc. One or more of them may be used in combination.

In the dilution of the sizing solution, it is preferable to use economical and safe water for dilution. When the sizing agent liquid is an aqueous dispersion, the concentration range in which water exists as a continuous phase is adjusted, but it is generally a method of sizing the sizing agent so that the amount of adhesion to the carbon fiber bundle becomes a desired amount. The liquid tank concentration is diluted to about 0.1% by mass to 10% by mass to impregnate the carbon fiber bundle. In order to adjust the sizing agent liquid to a desired tank concentration, when water is added to the sizing agent liquid for dilution, the sizing agent liquid may be diluted at one time according to the composition concentration of the main components other than the sizing agent water. Can be divided into multiple dilutions. In addition, the sizing agent liquid may contain various additives such as a surfactant, a smoothing agent, and an emulsifier in addition to the main component.

In the traveling direction of the carbon fiber bundle, the resin accumulation of the sizing agent liquid on the guide roller after the sizing agent applying step has passed is caused by the sizing that is taken out from the sizing agent tank by the carbon fiber bundle. Transfer of the agent liquid × retained on the guide roller and dried. When the resin of the sizing solution is dried on the guide roller to cause resin accumulation, the traveling carbon fiber bundle comes into contact with the resin accumulation on the guide roller, and the adhesion of the carbon fiber bundle when the carbon fiber bundle is separated from the resin becomes large, and fluff is generated. Or coiled and so on. In the method for producing a carbon fiber bundle of the present invention, the surface roller adhesion of the first guide roller after taking out the carbon fiber bundle from the liquid surface of the sizing agent tank is 0.2 N / cm ² or less, preferably When it is 0.1 N / cm ² or less, the sizing agent liquid on the guide roller can be prevented from drying and the sizing agent resin can be prevented from being accumulated. When the surface adhesiveness of the guide roller is more than 0.2 N / cm ² , fluff is generated from the carbon fiber bundle, and the problem of entanglement sometimes occurs. The guide roller surface adhesion is preferably maintained at 0.20 N / cm ² or less, and further maintained at 0.10 N / cm ² or less. In addition, the lower the surface adhesiveness of the guide roller, the better the quality of the carbon fiber bundle. However, the object of the present invention is to obtain a high-quality carbon fiber bundle with few fluff by preventing the drying of the sizing solution on the guide roller and the accumulation of resin. In addition, it is necessary to impart a sizing agent to the carbon fiber bundle. In addition, since the sizing agent is dried at least on the guide rollers to form a resin accumulation, the adhesiveness is generated. Therefore, the surface adhesiveness of the guide roller cannot be substantially zero, and the lower limit of the surface adhesiveness of the guide roller is preferably 0.01 N / cm ² .

Here, the surface adhesiveness of the guide roller is calculated by the following formula. Guide roller surface adhesion (N / cm ² ) = force at which the carbon fiber bundle starts to move / surface contact area of the guide roller of the carbon fiber bundle.

A calculation method of the force for starting the movement of the carbon fiber bundle will be described with reference to FIG. 5. It should be noted that the force for starting the movement of the carbon fibers was measured in the following manner within 10 minutes from the time of stopping the production of the carbon fiber bundles at the time of long-term stable production.

First, after the guide roller 3 to which the sizing agent liquid is attached is fixed in a non-rotating manner, the absolutely dried carbon fiber bundle 1 to be given the sizing agent is suspended from the uppermost point of the guide roller 3 with a contact angle of 180. ° State setting. Then, a loop is made on one end of the carbon fiber bundle 1 provided in the circumferential direction of the guide roller 3, a hook is attached to the front end portion of the load measuring device 7, and the hook is hooked on the ring of the carbon fiber bundle. The load measuring device is not particularly limited, and a push-pull meter capable of measuring an instantaneous maximum load is preferred. The carbon fiber bundle was slowly stretched with a load tester, and the maximum force at which the carbon fiber bundle 1 was about to start moving on the surface of the guide roller 3 was set as the force at which the carbon fiber started moving (in Newtons).

Furthermore, the term "stable production for a long period" refers to a case where there is no fluffing or entanglement and the production is industrially stable for a long period of time (24 hours or more). In addition, the stop of the manufacturing facility of a carbon fiber bundle refers to the point in time of stopping the manufacturing facility of the carbon fiber bundle including a sizing agent tank to a guide roller. The guide roller can be fixed for the first time by stopping the manufacturing equipment of the carbon fiber bundle, and the force for starting the movement of the carbon fiber bundle can be measured.

The force for starting the movement of the carbon fiber bundle can be adjusted by adjusting the degree of drying of the sizing solution adhered to the surface of the guide roller or changing the material of the guide roller.

In addition, the surface contact area of the guide roller of the carbon fiber bundle is a product of the circumferential length along the circumferential direction of the guide roller surface from the point where the carbon fiber bundle starts to contact on the guide roller to the point where the guide roller leaves. Out. The surface contact area can be changed by changing the contact circumferential length of the carbon fibers on the guide roller or the number of filaments of the carbon fiber bundle.

Then, the present invention will be described in more detail using drawings.

FIG. 1 is a schematic configuration diagram showing an example of a sizing application step in the present invention. In the state shown in FIG. 1, the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 through the impregnating roller 2, and is taken out from the liquid surface by the guide roller 3 and introduced to the next step of the sizing providing step. Drying step. In this aspect, the sizing agent liquid adheres to the guide roller 3 because the carbon fiber bundle 1 to which the sizing agent liquid has been passed. Therefore, in order to prevent the sizing agent liquid adhering to the guide roller 3 from being stuck, at least one contact body 5 selected from elastic raw materials such as cloth, resin, or rubber is brought into contact with the guide roller 3. The surface adhesiveness of the guide roller can be adjusted by wiping the sizing agent liquid adhered to the guide roller with the contact body 5 and is set to 0.2 N / cm ² or less.

Here, the method of contacting a contact body with a guide roller is not specifically limited, For example, the method of uniformly pressing a contact body to a guide roller, etc. are mentioned. The contact bodies involved in the pressing are elastic raw materials such as cloth, flannel, resin or rubber, metal, etc., as long as the sizing liquid adhering to the guide roller can be removed and the surface adhesiveness of the guide roller is set to 0.2 N / cm ² or less Just fine. In particular, in terms of the difficulty in generating static electricity, toughness, and water absorption, cotton flannel or wool fabrics with standing hairs such as plain-woven cotton cloth with fleece represented by calico or flannel are sizing. The effect of the agent liquid removal is the best.

The pressing force of the contact body is not particularly limited as long as the sizing agent liquid adhering to the guide roller can be removed, and the installation state of the contact body can be either fixed or rotated. Among them, if the pressing pressure is weak, the removal of the sizing solution is insufficient and the effect is weakened. On the other hand, if the pressing pressure is too high, the guide roller cannot be rotated, and a large amount of fluff is generated by the carbon fiber bundle traveling by rubbing. It is entangled with a guide roller, and a step passability is reduced. In this respect, the cloth-shaped contact body is preferably a rotatable roll with respect to the guide roller. Furthermore, the position where the contact body is pressed is not particularly limited, and in terms of preventing fluff × filament breakage caused by the contact between the contact body and the traveling carbon fiber bundle, it is preferable to perform the process on the surface of the carbon fiber bundle that has not come into contact with the traveling carbon fiber bundle. Press.

Furthermore, when pressing an elastic raw material or a metal, it is preferable that it is a sharp shape like a scraper in the point which does not give damage to a guide roller in terms of a sizing agent removal efficiency. When a doctor blade is used, when the guide roller rotates, the sizing liquid transferred on the surface of the guide roller is blocked by the sharp front end portion of the doctor blade contacting the guide roller. In addition, in order to efficiently block the sizing solution with the scraper blade with respect to the entire surface of the guide roller, it is preferable that the sharp front end portion of the scraper blade is in line contact with the axis direction of the guide roller in parallel. As the sharp part of the scraper, a hard scraper blade containing metal or plastic is preferred, so that it can uniformly remove adhesive deposits such as solid deposits or resin deposits generated on the guide roller when the sizing solution is dried. Thing. In addition, in order to remove the sizing solution with the blade across the entire width of the guide roller, a guide device such as a guide rail for the blade of the blade may be provided in a direction parallel to the axis of the guide roller, and in the axial direction of the guide roller. Set the scraper. Thereby, solid attachments or adhesive attachments on the guide roller can be efficiently removed.

FIG. 2 is a schematic configuration diagram showing another example of a sizing application step in the present invention. In the state shown in FIG. 2, the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 by the impregnating roller 2, and is taken out from the liquid surface by the guide roller 3 and introduced to the next step of the sizing providing step. Drying step. In this aspect as well, the sizing agent liquid is adhered to the guide roller 3 because the carbon fiber bundle 1 provided with the sizing agent liquid passes through. Therefore, in order to prevent the sizing agent from adhering to the guide roller 3, the sizing agent liquid spraying device 6 or the like is used to apply the sizing agent liquid to the sizing agent liquid from the sizing agent liquid tank 4 to the sizing agent liquid. Guide roller 3. The method for applying the sizing agent liquid is not particularly limited to the sizing agent spraying device 6, and examples thereof include a method of dropping or spraying the sizing agent liquid onto the entire surface of the guide roller, and immersing the guide roller in the sizing agent liquid. Method, etc. In this aspect, the sizing agent liquid should be provided to the extent that the guide roller is not dried, and the surface adhesiveness of the guide roller should be 0.2 N / cm ² or less, as long as the sizing agent is not on the surface of the guide roller. There is no particular limitation on the resin accumulation due to retention × drying.

For example, as shown in FIG. 2, a sizing agent spraying device 6 is provided on the upper portion of the guide roller 3, and the sizing agent liquid is sprayed from the sizing agent spraying device 6, whereby the sizing on the guide roller 3 can be sufficiently suppressed. Dry the solution. Regarding the sizing spray amount sprayed by the sizing agent spraying device 6, the upper limit is not particularly limited as long as the guide roller 3 is wetted, and a preferred range is 50 mg / cm ² / hr to 130 mg / cm ² / hr, more preferably in the range of 80 mg / cm ² / hr to 100 mg / cm ² / hr. When the spraying amount is less than 50 mg / cm ² / hr, there are cases in which the sizing agent liquid is evaporated on the guide roller 3 to cause resin accumulation and fluff or entanglement. When the spray amount exceeds 130 mg / cm ² / hr, the sizing amount is excessively used, which is disadvantageous in terms of cost.

In addition, as shown in FIG. 3, by immersing the guide roller 3 in a sizing agent liquid tank 8 different from the sizing agent liquid tank used in the sizing providing step, the sizing on the guide roller 3 can be sufficiently suppressed. Dry the solution.

As shown in FIG. 2 or FIG. 3, the sizing agent liquid separately provided to the guide roller is not particularly limited, and it is preferable not to change the composition and amount of the sizing agent provided to the obtained carbon fiber bundle. Is more preferably the same as the sizing agent solution impregnated with the carbon fiber bundle.

Furthermore, by combining the method of contacting the contact body with the guide roller and the method of applying the sizing agent liquid independently of the sizing agent liquid tank 4, the effect is further enhanced. For example, as shown in FIG. 4, after the sizing agent is sprayed from the sizing agent spraying device 6 to the guide tube 3, the contact body is pressed, and the contact body can be surely prevented from being pressed by the method of pressing only the contact body. The slurry is fixed and the remaining sizing solution is removed, and the surface adhesiveness of the guide roller is adjusted to a predetermined range.

Furthermore, in the present invention, it is preferable to use a guide roll having water repellency as the guide roll 3 so that the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 through the impregnating roll 2, and the guide roll 3 is used. When it is taken out from the liquid surface and introduced into the drying step which is the next step of the sizing providing step, no resin accumulation due to the sizing agent liquid occurs on the guide roller 3. Specific examples of the water-repellent guide roller include a fluorine resin or stainless steel (SUS). In particular, since the carbon fiber bundle provided with the sizing agent flows on the guide roller and the surface of the guide roller is always in a wet state, stainless steel (SUS) which is less prone to rust is more preferable. The types of stainless steel include SUS304, SUS304L, SUS316, and SUS316L.

Further, in the manufacturing method of the present invention, after the carbon fiber bundle is immersed in the sizing agent solution, the position from the liquid surface to the first guide roller contacted and the position from the guide roller to the drying step are placed on the adjacent wire. A sizing agent liquid film is easily formed between the bars. The sizing agent film can be imparted to the sizing agent liquid by the remaining sizing agent solution carried out by the carbon fiber bundle immersed in the sizing agent solution tank, or independently of the sizing agent solution of the sizing agent solution tank as described above. It is formed by the sizing solution of the guide roller. If a sizing agent liquid film is formed between adjacent yarns, the adjacent yarns are in contact with each other due to the surface tension of the sizing agent liquid film, and fluff is generated, or the sizing agent adhesion spot or drying spot, color tone of the obtained carbon fiber bundle Spots increase. Therefore, it is preferable to remove the sizing agent liquid film at each position. The method of removing the sizing agent liquid film is not particularly limited, and examples thereof include spraying of pressurized gas, application of vibration, application of ultrasonic waves, physical contact caused by providing a guide, and the like. Among them, a non-contact method is preferable in order to easily prevent the generation of fluff in the carbon fiber bundle, and further, from the viewpoint of suppressing the equipment cost to a low level, the ejection of pressurized gas is more preferable.

In the manufacturing method of the present invention, the tension of the carbon fiber bundle in the sizing agent applying step is preferably set to 3.5 cN / tex to 8.5 cN / tex. When the tension is 3.5 cN / tex or more, a decrease in the convergence of the carbon fiber bundle can be prevented. On the other hand, when it is 8.5 cN / tex or less, it is possible to easily prevent the generation of fluff and broken yarn caused by the application of tension. From the above viewpoint, the tension of the carbon fiber bundle in the sizing agent applying step is preferably set to 3.5 cN / tex to 8.5 cN / tex, more preferably 4.0 cN / tex to 8.0 cN / tex, and even more preferably 4.5 cN / tex ～ 7.5 cN / tex. In addition, the tension of the carbon fiber bundle in the sizing agent applying step may be controlled individually only in the sizing agent applying step, or may be controlled together with the tension in the drying step by the same mechanism. The method of controlling the tension is not particularly limited, and examples thereof include a method of adjusting a ratio of the driving speed before and after the sizing agent applying step. The step tension can be grasped by measuring a traveling wire to which the sizing agent liquid is to be applied by using a tensiometer or the like, and can be adjusted by a rotation torque of the rollers before and after the sizing agent is applied.

Regarding the carbon fiber bundle, in the sizing agent applying step, the sizing agent liquid is applied, and then the drying step is performed at about 200 ° C. to 300 ° C. and wound around a paper tube. The drying method can be used alone or in combination with a contact type dryer such as a drum type or a non-contact hot air dryer, and is not particularly limited. [Example]

The present invention will be described more specifically with reference to examples and comparative examples. In addition, each evaluation item in an Example and a comparative example was implemented by the following evaluation method.

[Guide roller surface adhesion degree] The guide roller surface adhesion degree is calculated by the following formula. Roller surface adhesion (N / cm ² ) = force at which the carbon fiber bundle starts to move / surface contact area of the guide roller of the carbon fiber bundle.

The force for starting the movement of the carbon fiber bundle was measured 5 minutes after the equipment for manufacturing the carbon fiber bundle when the long-term stable production was stopped, and was measured in the following manner. That is, as shown in FIG. 5, after the sizing agent-containing stainless steel guide roller 3 is fixed in a non-rotating manner, the absolutely dried carbon fiber bundle 1 to be applied to the sizing agent is self-guided. The uppermost point is suspended with a contact angle of 180 °. Thereafter, a loop is formed at one end of the carbon fiber bundle 1. As the load measuring device 7, a digital push-pull meter (RX series, product number RX-10) manufactured by AIKOH ENGINEERING (stock) was used. Attach a hook as a gauge attachment (No. 011B) to the front end of the digital push-pull meter, and hang the hook on the ring of the carbon fiber bundle 1. In this state, the guide roller 3 The carbon fiber bundle 1 is slowly drawn in the circumferential direction. The push-pull force meter was used to measure the maximum force of the carbon fiber bundle 1 on the surface of the guide roller 3 which is about to start moving, that is, the force to start the carbon fiber bundle.

The surface contact area of the guide roller of the carbon fiber bundle is calculated by the product of the circumferential length of the guide roller that the carbon fiber bundle contacts and the wire width of the carbon fiber bundle.

[Quality] As the quality of the carbon fiber bundle provided with the sizing agent, the end face fluff of the bobbin of the packaged carbon fiber bundle was observed, and judged based on the following criteria. ◎ = fluff is less than 5/100 mm ² ○ = fluff was 5/100 mm ² or more, less than 10/100 mm ² × = fluff of 10/100 mm ² or more

[Example 1] A sizing agent was applied to a plurality of parallel carbon fiber bundles in a configuration shown in FIG. 1 and a drying step was performed to obtain a carbon fiber bundle provided with a sizing agent.

Specifically, 3,000 carbon fiber bundles each having a polyacrylonitrile-based fiber as a precursor fiber bundle were immersed in a sizing agent tank, and then fed to a drying step to obtain a sizing agent-added carbon fiber. The sizing agent liquid tank is filled with a sizing agent solution having a concentration of 3% by mass based on a bisphenol A type epoxy resin as an aromatic epoxy compound as a main component. As the guide roller 3 which is first contacted as the carbon fiber bundle taken out from the liquid surface of the sizing agent, a guide roller including stainless steel (SUS) is used, and a cotton flannel cloth with standing hair as the contact body 5 is pressed against the guide roller 3 The bottom.

The surface adhesiveness of the guide roller 3 is 0.05 N / cm ² , and the quality of the end face fluff is extremely good. The results are shown in Table 1.

[Example 2] A carbon fiber bundle to which a sizing agent was imparted was obtained in the same manner as in Example 1 except that a plastic blade was used instead of the cotton flannel cloth having standing hair as the contact body 5. The surface adhesiveness of the guide roller 3 was 0.07 N / cm ² , and the end face fluff quality was extremely good. The results are shown in Table 1.

[Example 3] A carbon fiber bundle to which a sizing agent was imparted was obtained in the same manner as in Example 1 except that the sizing agent applying step was the step shown in FIG. 2. That is, the same procedure as in Example 1 was carried out except that the sizing agent was sprayed from the upper part of the guide roller 3 which was first contacted after the carbon fiber bundle was taken out from the sizing agent liquid surface, and the contact body was removed. The spray amount of the sizing agent liquid at this time was set to 100 mg / cm ² / hr. The surface adhesiveness of the guide roller 3 is 0.04 N / cm ² , and the end face fluff quality is extremely good. The results are shown in Table 1.

[Example 4] A carbon fiber bundle was obtained in the same manner as in Example 3 except that the spray amount of the sizing agent liquid was changed to 80 mg / cm ² / hr. The surface adhesiveness of the guide roller 3 was 0.13 N / cm ² , and the quality of the end face fluff was good. The results are shown in Table 1.

[Example 5] A carbon fiber bundle to which a sizing agent was imparted was obtained in the same manner as in Example 1 except that the sizing agent applying step was the step shown in FIG. 3. That is, in Example 1, the guide rollers 3 that first contacted after the carbon fiber bundle was taken out from the sizing agent liquid surface were immersed in another independent sizing agent liquid tank 8 and the contact bodies were removed. Example 1 was performed in the same manner. The surface adhesiveness of the guide roller 3 was 0.08 N / cm ² , and the end face fluff quality was good. The results are shown in Table 1.

[Example 6] A carbon fiber bundle provided with a sizing agent was obtained in the same manner as in Example 1 except that the sizing agent applying step was the step shown in FIG. 4. That is, the same procedure as in Example 1 was performed except that the sizing agent solution was sprayed on the carbon fiber bundle sent from the guide roller 3 at a spray amount of 80 mg / cm ² / hr. The surface adhesiveness of the guide roller 3 is 0.02 N / cm ² , and the end face fluff quality is extremely good. The results are shown in Table 1.

[Example 7] Except that the sizing agent tank was filled with a sizing agent solution having a concentration of 2% by mass of polyurethane as a main component, all operations were performed in the same manner as in Example 1 to obtain a sizing agent. Carbon fiber bundle. The surface adhesiveness of the guide roller 3 is 0.06 N / cm ² , and the end face fluff quality is extremely good. The results are shown in Table 1.

[Comparative Example 1] A carbon fiber bundle to which a sizing agent was imparted was obtained in the same manner as in Example 1 except that the sizing agent applying step was the step shown in FIG. 6. That is, it carried out similarly to Example 1 except not pressing the cotton flannel cloth as a contact body. As a result, the sizing agent was dried on the guide roller to cause resin accumulation. The surface adhesiveness of the guide roller 3 was increased to 0.25 N / cm ² , and the traveling carbon fiber bundle was fluffed, and the quality of the end face fluff was significantly deteriorated. The results are shown in Table 1.

[表 1] Table 1 ※ ◎ = fluff fluff quality is less than 5/100 mm ² ○ = fluff was 5/100 mm ² or more, less than 10/100 mm ² × = fluff of 10/100 mm ² or more

1‧‧‧ carbon fiber bundle

2‧‧‧ roller for dipping

3‧‧‧Guide roller

4‧‧‧ sizing agent tank

5‧‧‧ contact

6‧‧‧ sizing agent spray device

7‧‧‧ Load Tester

8‧‧‧ Sizing agent tank different from sizing agent tank 4

FIG. 1 is a schematic configuration diagram showing an example of a sizing application step in the present invention. FIG. 2 is a schematic configuration diagram showing another example of a sizing application step in the present invention. It is a schematic block diagram which shows the other example of a sizing application process in this invention. It is a schematic block diagram which shows the other example of a sizing application process in this invention. FIG. 5 is a diagram showing a method of calculating a force for starting the movement of the carbon fiber bundle. FIG. 6 is a schematic configuration diagram showing an example of a conventional sizing application step.

Claims (3)

A manufacturing method of a carbon fiber bundle provided with a sizing agent, wherein a sizing agent providing step of immersing a plurality of carbon fiber bundles in parallel in a sizing agent liquid tank is followed by a drying step to obtain a carbon fiber provided with a sizing agent. Bundle, in the method for producing a carbon fiber bundle provided with a sizing agent, the first guide roller after immersing the carbon fiber bundle in a sizing agent tank and taking out the carbon fiber bundle from the liquid surface of the sizing agent tank The surface adhesiveness of the guide roller is set to 0.2 N / cm ² or less. The manufacturing method of the carbon fiber bundle provided with the sizing agent as described in the 1st patent application range whose surface adhesiveness of a guide roller is 0.2 N / cm <^2> or less by making a contact body contact a guide roller. As described in the method for manufacturing a carbon fiber bundle provided with a sizing agent according to item 1 of the scope of the patent application, the sizing agent liquid is added after the sizing agent applying step, thereby setting the surface roller adhesion to 0.2 N. / cm ² or less.