JP5870526B2 - Method for producing carbon fiber bundle impregnated with sizing agent solution - Google Patents

Description

  The present invention relates to a method for producing a carbon fiber bundle impregnated with a sizing agent solution used for a carbon fiber reinforced composite material or the like.

  One of the fiber reinforced composite materials is a carbon fiber reinforced resin composite material formed of a reinforcing material made of carbon fiber and a matrix resin. As the matrix resin, various resins such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, and a phenol resin are used. Of these, an epoxy resin is widely used. Generally, carbon fibers have a diameter of about 5 to 8 μm, and are used in a form in which a plurality of single fibers are collected (hereinafter referred to as “carbon fiber bundles”). Since carbon fiber has a low elongation and a brittle nature, fluff is likely to occur due to mechanical friction or the like, and the handleability is not good. In addition, since the wettability to the matrix resin is poor, when used as a reinforcing material for a reinforced composite material, the excellent properties as a carbon fiber reinforcing material may not be sufficiently exhibited. For this reason, conventionally, a sizing agent has been added to carbon fibers for the purpose of improving processability, handleability, and wettability with a matrix resin (hereinafter sometimes referred to as “adhesion”). Yes.

  In the sizing treatment in which the sizing agent is applied to the carbon fiber, a sizing agent solution in which the sizing agent is dispersed or dissolved in water or an organic solvent such as acetone is usually used. However, the use of the sizing agent as an aqueous dispersion in which the sizing agent is dispersed in water is more industrially and safer than the case where the sizing agent is used by being dissolved or dispersed in an organic solvent. In addition, as a method for applying the sizing agent to the surface of the carbon fiber, the carbon fiber bundle is impregnated with a sizing agent solution by a roller (hereinafter also referred to as “roll”) dipping method, a roller contact method, etc. The roller dipping method is often used from the viewpoint of productivity and uniform adhesion of the sizing agent. Hereinafter, the carbon fiber bundle before impregnated with the sizing agent liquid and dried may be referred to as a “sizing agent liquid-impregnated carbon fiber bundle”.

  In order to improve the productivity of carbon fibers, a plurality of (for example, several tens to several hundreds) carbon fiber bundles are generally arranged in parallel to form a multi-fiber bundle. When impregnating the carbon fiber bundle with the sizing agent solution, the following occurred. That is, a sizing agent liquid film is formed between adjacent sizing agent liquid-impregnated carbon fiber bundles immediately after coming out of the sizing agent liquid surface, and the surface of the sizing agent liquid film is reduced. In some cases, the tension acts on the sizing agent solution-impregnated carbon fiber bundle, and the yarn width of the sizing agent solution-impregnated carbon fiber bundle is widened.

  In general, after the carbon fiber bundle has passed through the sizing agent solution immersion tank, the roller (pull-up roller) for pulling out the sizing agent solution-impregnated carbon fiber bundle from the sizing agent solution immersion tank and the purpose of thread path control A guide roller such as a grooved roller, or a draining roller (for example, a nip roller consisting of two pairs of rollers) for the purpose of adjusting the amount of sizing agent adhering to the carbon fiber and reducing the load in the drying process is arranged. A drying process is performed after passing through a roller. Further, a drying roller may be disposed immediately after the sizing agent solution immersion tank, and the sizing agent solution impregnated carbon fiber bundle may be pulled up and dried at the same time. In this way, another roller can also serve as a pulling roller.

  Many sizing treatment methods for carbon fibers and methods for controlling the yarn width of carbon fiber bundles in the sizing treatment step are known. In Patent Document 1, a carbon fiber bundle impregnated with a sizing agent solution is flattened by bringing it into contact with a heated roll under tension, and a method for producing a carbon fiber bundle having a yarn width of 15 times the thickness or more is proposed. Yes.

  In Patent Documents 2 to 4, the carbon fiber bundle is immersed in the sizing agent solution, and then the pressurized gas is blown to suppress over-adhesion of the sizing agent generated by the fluff inherent in the carbon fiber bundle. It is described that adhesion spots of the sizing agent can be suppressed by removing the film of the sizing agent liquid generated between the fiber bundles.

  Further, in Patent Documents 5 and 6, for the purpose of draining the carbon fiber bundle impregnated with the sizing agent solution, pressure is applied to the carbon fiber bundle on the guide roller disposed after the tank storing the sizing agent solution. It has been proposed to inject gas.

  In Patent Document 7, the carbon fiber bundle has a moisture content of 0.2 to 10% by weight, and then a sizing agent is applied and dried, and then wound around a bobbin. During these steps, the tension of the carbon fiber bundle is set. A method of manufacturing a carbon fiber package that is wound around a bobbin while stabilizing the yarn width of a carbon fiber bundle to which a sizing agent has been applied has been proposed by adjusting to 0.5 to 6.5 gf / Tex.

Japanese Patent Laid-Open No. 1-292038 Japanese Patent Laid-Open No. 7-145549 JP-A-8-284071 JP 2003-278032 A JP 2002-339222 A JP 2003-293260 A JP 2008-7925 A

  In the method described in the above-mentioned patent document, there is a case where a sizing agent liquid film is formed between adjacent sizing agent liquid-impregnated carbon fiber bundles and contacts a pulling roller such as a guide roller. The generated sizing agent liquid film disappears when it comes into contact with the pulling roller. However, since the carbon fiber bundle is in contact with the pulling roller in a state where the film is formed, the widening of the yarn width may be promoted. In particular, when the nip roller and the drying roller as described above also serve as the pulling roller, the influence becomes remarkable. In addition, on the roller such as a pulling roller, the widened state of the yarn width of the carbon fiber bundle generated at one end is maintained as it is, so that the carbon fiber bundle obtained through the subsequent drying treatment has a result that the yarn width is widened as a result. It became.

  Therefore, a difference in yarn width between a sizing agent liquid-impregnated carbon fiber bundle in which a film of a sizing agent liquid is formed and the yarn width is widened, and a sizing agent liquid-impregnated carbon fiber bundle in which the yarn width is not widened This was a cause of uneven yarn width between carbon fiber bundles produced in parallel. Furthermore, since this phenomenon (film formation) does not occur continuously in the fiber axis direction of the carbon fiber bundle impregnated with the sizing agent solution, it also causes thread width unevenness in the fiber axis direction of one carbon fiber bundle. It was.

  Specifically, according to the method of Patent Document 1, it is possible to expand the carbon fiber bundle relatively easily, but it is not possible to eliminate the widening state of the yarn width by the film of the sizing agent liquid as described above. In some cases, thread width unevenness may occur.

  In Patent Documents 2 to 4, a guide roller is disposed after the carbon fiber bundle is immersed in a sizing agent solution, and a nozzle that injects pressurized gas is disposed thereafter. As described above, when a sizing agent liquid-impregnated film is formed between adjacent sizing agent liquid-impregnated carbon fiber bundles, the sizing agent liquid-impregnated carbon fiber bundle may come into contact with the guide roller in a state where the yarn width is widened. For this reason, there are cases where it is insufficient to eliminate the yarn width unevenness of the carbon fiber bundle.

  In addition, when the liquid film is to be removed before the sizing agent liquid-impregnated carbon fiber bundle is widened by the methods described in Patent Documents 5 and 6, the flow rate of the pressurized gas needs to be set high. However, if the flow rate of the pressurized gas is too high, the carbon fiber may be damaged and fluff may be generated, or the sizing solution may be scattered around and the inside of the field may be contaminated. When the flow rate of the pressurized gas is set low, it is difficult to remove the liquid film. As a result, widening of the yarn width of the sizing agent liquid-impregnated carbon fiber bundle occurs, and uneven yarn width may occur. . Further, in this method, since the pressurized gas directly hits the guide roller, the sizing agent is likely to be dried and fixed on the guide roller, which may cause fluff and yarn breakage. Furthermore, when the pulling roller disposed after the carbon fiber bundle has passed through the sizing agent solution immersion tank is a nip roller, a pressurized gas injection nozzle can be disposed without interfering with the two rollers. It was sometimes difficult.

  Moreover, even when the moisture content and tension of the carbon fiber bundle immediately before applying the sizing agent are controlled as in the method described in Patent Document 7, the formation of the sizing agent liquid film as described above is suppressed or removed. In some cases, it was not sufficient to eliminate the uneven yarn width of the carbon fiber bundle.

  For this reason, the present invention reduces the variation of the yarn width in the fiber axis direction in the carbon fiber bundle impregnated with the sizing agent solution, and further enables the yarn width to be uniform among the plurality of carbon fiber bundles processed in parallel. It aims at providing the manufacturing method of an agent liquid impregnation carbon fiber bundle.

In the present invention, a plurality of parallel running carbon fiber bundles are immersed in a sizing agent solution, and then immersed in the sizing agent solution via a pulling roller disposed above the surface of the sizing agent solution. A method for producing a carbon fiber bundle impregnated with a sizing agent solution comprising a sizing treatment step of performing a drying treatment after pulling up the plurality of carbon fiber bundles,
In the sizing treatment step, the sizing is performed before the plurality of carbon fiber bundles travel on the intermediate point of the traveling path from the time when the carbon fiber bundle comes out of the liquid surface of the sizing agent solution and comes into contact with the pulling roller. It is a manufacturing method of the sizing agent liquid impregnation carbon fiber bundle which removes the film | membrane of this sizing agent liquid formed between the adjacent carbon fiber bundles of this several carbon fiber bundle after coming out from the liquid level of a chemical | medical solution.

  According to the present invention, the carbon fiber bundle impregnated with the sizing agent solution reduces the variation in the yarn width in the fiber axis direction, and further impregnates the yarn width among the plurality of carbon fiber bundles processed in parallel. A method for producing carbon fiber is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the apparatus schematic for demonstrating an example of the manufacturing method of the sizing agent liquid impregnation carbon fiber bundle which concerns on this invention, (a) is the front schematic of an apparatus, (b) is a plane schematic. It is the apparatus schematic for demonstrating another example of the manufacturing method of the sizing agent liquid impregnation carbon fiber bundle which concerns on this invention, (a) is the front schematic of an apparatus, (b) is a plane schematic. . It is the apparatus schematic for demonstrating another example of the manufacturing method of the sizing agent liquid impregnation carbon fiber bundle which concerns on this invention, (a) is the front schematic of an apparatus, (b) is a plane schematic. is there. It is the apparatus schematic for demonstrating an example of the manufacturing method of the conventional sizing agent liquid impregnation carbon fiber bundle. It is the apparatus schematic for demonstrating another example of the manufacturing method of the conventional sizing agent liquid impregnation carbon fiber bundle. It is the apparatus schematic for demonstrating another example of the manufacturing method of the conventional sizing agent liquid impregnation carbon fiber bundle. It is the apparatus schematic for demonstrating another example of the manufacturing method of the conventional sizing agent liquid impregnation carbon fiber bundle.

  Since the present inventors do not lose the widening state of the carbon fiber bundle caused by the sizing agent liquid film, the film of the sizing agent liquid is expanded before the sizing agent liquid-impregnated carbon fiber bundle is widened, that is, It was found that it is important to remove carbon fiber bundles of uniform yarn width as early as possible at the same time as the formation thereof, and the present invention has been achieved. Specifically, in the present invention, at least before the carbon fiber bundle travels an intermediate point of the travel path (yarn path) that travels from the liquid surface of the sizing agent until it comes into contact with the pulling roller. Remove the membrane. For this reason, compared with the method of patent documents 1-7, the widening of the thread width of the sizing agent liquid impregnation carbon fiber bundle can be suppressed more.

  In addition, from the viewpoint of suppressing the promotion of widening of the yarn width, the present inventors, as a method for removing the film, only the film without bringing a solid such as a roller into contact with the carbon fiber bundle in a state where the film is formed. It has been found that it is preferable to employ a removal method (for example, a method using a pressurized gas or a rod-like material described later).

  Hereinafter, each material used in the present invention will be described.

(Carbon fiber bundle)
The carbon fiber bundle used in the present invention may be obtained from any raw material such as pitch, rayon and polyacrylonitrile. Moreover, any of a high strength type (low elastic modulus carbon fiber bundle), a medium high elasticity carbon fiber bundle, and an ultra high elasticity carbon fiber bundle may be sufficient. However, a polyacrylonitrile-based carbon fiber bundle is preferable from the viewpoint of high strength and high elasticity.

  Moreover, there is no limitation in particular also about the form of the carbon fiber used as a raw material in this invention, For example, the diameter of carbon fiber can be 3 micrometers or more and 10 micrometers or less. Moreover, there is no limitation in particular also about the number of the carbon fibers which comprise a carbon fiber bundle, For example, it can be 1000-100000. In addition, when making the carbon fiber reinforced composite material, in order to easily improve the affinity and adhesion between the carbon fiber and the matrix resin, the carbon fiber is subjected to electrolytic oxidation treatment in an electrolytic solution or in a gas phase or a liquid phase. It is preferable to perform an oxidation treatment and surface treatment.

(Sizing solution)
As the sizing agent liquid used in the present invention, a sizing agent dispersed or dissolved in water or an organic solvent such as acetone can be used. From the viewpoint of industrial and safety, the sizing agent is dispersed in water. Alternatively, a dissolved aqueous dispersion or aqueous solution is preferable.

  In addition, the said sizing agent can use a well-known thing in the field | area of carbon fiber as needed. The sizing agent can contain the main ingredient and various additives mentioned later, for example, can consist of a main ingredient and an emulsifier. By drying the carbon fiber bundle impregnated with the sizing agent solution, a carbon fiber bundle having a sizing agent attached to the surface of the carbon fiber can be obtained.

  As the main component (main component) of the sizing agent, epoxy resin, epoxy-modified polyurethane resin, polyester resin, phenol resin, polyamide resin, polyurethane resin, polycarbonate resin, polyetherimide resin, polyamideimide resin, polyimide resin, bismaleimide resin, A urethane-modified epoxy resin, a polyvinyl alcohol resin, a polyvinyl pyrrolidone resin, a polyether sulfone resin, and the like can be mentioned, and can be appropriately selected according to the matrix resin to be combined when the carbon fiber reinforced composite material is used.

  These may be used alone or in combination of two or more. The concentration of the sizing agent in the sizing agent liquid depends on the type of the sizing agent, but when the sizing agent liquid is an aqueous dispersion, it is preferable to adjust the concentration range so that water exists as a continuous phase. Usually, it is prepared at a concentration of 10% by mass or more and 50% by mass or less. Although the concentration can be less than 10% by mass in the preparation stage of the aqueous dispersion of the sizing agent, the proportion of water in the aqueous dispersion increases as compared with the case of 10% by mass or more. It may be economically inferior in terms of transportation and storage from the preparation of the liquid to its use (carbon fiber sizing treatment). For this reason, when the concentration of the sizing agent is less than 10% by mass, the sizing agent solution is about 0.1 to 10% by mass so that a desired adhesion amount is obtained during use (carbon fiber sizing treatment). A method of diluting in a low concentration aqueous solution and impregnating the carbon fiber is common. The sizing agent liquid may contain various additives such as a surfactant, a smoothing agent, and an emulsifier in addition to the main component and water.

<Sizing process>
(Impregnation method of sizing solution)
The method for impregnating the carbon fiber bundle with the sizing agent liquid can be selected as necessary from known impregnation methods in the field of carbon fiber, but the carbon fiber bundles are arranged in parallel at equal intervals to form a sheet. It is preferable from the viewpoint of productivity to use a method of immersing in a chemical solution. The distance between the carbon fiber bundles arranged in parallel and the number of the carbon fiber bundles are not particularly limited in the present invention, and can be appropriately selected according to the width of the apparatus. Depending on the degree of the gap between the carbon fiber bundles, the sizing agent liquid film formed between the adjacent carbon fiber bundles is easily formed and the frequency is different. It is desirable to perform an operation for removing the film of the chemical solution.

In addition, when a tank storing the sizing agent liquid is used when the carbon fiber bundle is impregnated with the sizing agent liquid, depending on the type of the sizing agent liquid, the installation position of the stored tank, etc., for example, the sizing agent liquid Can be used in which a dipping roller for impregnating the carbon fiber bundle is disposed. At that time, the number of immersion rollers is not particularly limited, and the size of the tank can be appropriately selected depending on the number of carbon fiber bundles.
The immersion roller is a roller that is partially or entirely immersed in the sizing agent solution, and is, for example, a roller represented by reference numeral 2 in FIG. The carbon fiber bundle can be easily impregnated with the sizing agent liquid by bringing the carbon fiber bundle into contact with the roller in the sizing agent liquid.

(Method for removing film of sizing solution)
In the method for producing a carbon fiber bundle impregnated with the sizing agent liquid of the present invention, the carbon fiber bundle is located before the middle point of the distance from the surface of the sizing agent liquid until it comes into contact with the pulling roller (guide roller or nip roller). The film of the sizing agent solution formed between adjacent sizing agent solution-impregnated carbon fiber bundles is removed. Furthermore, if this removal operation is performed at a position immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid, particularly at a position where the carbon fiber bundle comes out from the liquid surface, it is almost simultaneously with the formation of the film of the sizing agent liquid. Can be removed (or the formation itself can be suppressed). By removing the liquid film formed between adjacent sizing agent liquid-impregnated carbon fiber bundles at the position as described above before contacting the pulling roller, the yarn width is greatly widened by the film of the sizing agent liquid. Therefore, it is possible to obtain a yarn width having the same quality as that of other carbon fiber bundles in which a film of the sizing agent solution is not formed, and to eliminate occurrence of yarn width unevenness in the fiber axis direction.

  As described above, one roller (for example, a nip roller) can also serve as a pulling roller for pulling up the carbon fiber bundle and another role (for example, a role as a draining roller). Since these rollers are usually arranged immediately after the carbon fiber bundle has passed through the sizing agent solution immersion tank, the pulling roller has a carbon fiber bundle immersed in the sizing agent solution that exposes the liquid surface of the sizing agent solution. It can be the first roller to contact after.

  In addition, formation and disappearance of the sizing agent liquid film, that is, by repeating the widening and narrowing of the yarn width in the direction of the carbon fiber bundle fiber axis, the running position of the carbon fiber bundle swings to the left and right, and makes contact with the adjacent carbon fiber bundle. There is a case. In the case of contact, fiber mixing, fluff and yarn breakage may occur between the carbon fiber bundles. In order to prevent such contact with adjacent carbon fiber bundles, it is preferable to remove the formed sizing agent liquid film at an early stage, more preferably almost simultaneously with the formation.

  In the present invention, at least the carbon fiber bundle removes the film of the sizing agent liquid before traveling on the intermediate point of the traveling path of the carbon fiber bundle between the liquid surface of the sizing agent liquid and the pulling roller. Compared with this method, the contact between the carbon fiber bundles can be prevented, and the occurrence of blending, fluff and yarn breakage between the carbon fiber bundles can be prevented.

  As a method for removing the sizing agent liquid film formed between adjacent sizing agent solution-impregnated carbon fiber bundles, a method of injecting pressurized gas is preferably used. The pressurized gas only needs to have a mechanism that is directly jetted onto a sizing agent liquid film formed between adjacent sizing agent liquid-impregnated carbon fiber bundles. At this time, the carbon fiber bundle impregnated with the sizing agent solution may or may not be injected. That is, the pressurized gas may be in contact with the carbon fiber bundle as well as the film of the sizing agent solution, or may not be in contact.

  At that time, when the pressurized gas directly hits the pulling roller, the sizing agent liquid adhering to the surface of the pulling roller is easily dried and fixed. Since this fixed sizing agent also causes fluff and thread breakage, it is more preferable to inject pressurized gas so that the pressurized gas does not directly hit the pulling roller. For example, by arranging the injection nozzle 4 for injecting the pressurized gas as shown in FIG. 1, the sizing agent liquid film between the adjacent carbon fiber bundles is not directly applied to the guide roller 5. Formation can be suppressed or eliminated.

  Air is preferably used as the gas used for the pressurized gas. Furthermore, in order to remove foreign substances such as dust existing in the gas, it is preferable to inject pressurized gas that has passed through a filter. Moreover, the injection speed of the pressurized gas may be appropriately adjusted to a speed at which the film of the sizing agent liquid generated between adjacent carbon fiber bundles can be removed, and depends on the viscosity of the sizing agent liquid and the number of carbon fiber bundles, For example, it may be adjusted at 1.0 to 30.0 m / second or less in a gas collision portion (a portion where a jetted pressurized gas and a sizing agent liquid-impregnated carbon fiber bundle collide). If it is this range, since the film | membrane of a sizing agent liquid can be removed easily and it can prevent fluff generation | occurrence | production and a sizing agent liquid scattering to the circumference | surroundings and contaminating in the field, it is preferable.

  Furthermore, when using the method of injecting pressurized gas to a carbon fiber bundle, the injection nozzle provided with the pressurized gas blower which blows off pressurized gas can be used. As the spray nozzle, a sector nozzle, a slit nozzle, a columnar nozzle, or the like can be used. Depending on the fineness and number of single fibers constituting the carbon fiber bundle, after applying a sizing agent liquid to the carbon fiber bundle, a pressurized gas is injected into each gap between adjacent sizing agent liquid-impregnated carbon fiber bundles. The pressurized gas may be ejected by arranging ejection nozzles corresponding to the number of gaps. Further, an arbitrary number of injection nozzles may be arranged to inject the pressurized gas into the carbon fiber bundle so that the pressurized gas is injected into the plurality of fiber bundle groups or the entire fiber bundle.

  Also, the pressurized gas outlet of the injection nozzle is located at a position before the middle point of the distance from when the carbon fiber bundle comes out of the surface of the sizing agent liquid until it comes into contact with the pulling roller (guide roller or nip roller). In addition, it is arranged so that a pressurized gas is injected into every gap between adjacent sizing agent solution-impregnated carbon fiber bundles, or a pressurized gas is injected over the entire fiber bundle. At this time, the pressurized gas outlet of the spray nozzle is arranged at a position immediately after pulling up the carbon fiber bundle from the sizing agent liquid, that is, immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid. Is preferably removed. For example, the generation of the film of the sizing agent liquid can be substantially suppressed by injecting the pressurized gas to the position where the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid. Furthermore, the distance between the pressurized gas outlet of the injection nozzle and the carbon fiber bundle is preferably 1 cm or more and 10 cm or less. If the distance between the pressurized gas outlet of the spray nozzle and the carbon fiber bundle is within this range, the sizing agent liquid removed from the carbon fiber bundle by the pressurized gas will scatter and induce clogging of the nozzle hole. It is preferable because it can be easily prevented from causing in-site contamination. More preferably, it is 2 cm or more and 8 cm or less.

  The angle formed by the pressurized gas outlet of the spray nozzle and the carbon fiber bundle is not particularly limited as long as it is an angle that can remove the film of the sizing agent liquid generated between the adjacent carbon fiber bundles, and can be appropriately selected. . At that time, it is preferable to appropriately adjust the sizing agent liquid as described above or the sizing agent liquid stored in the tank so that the sizing agent liquid is not scattered around by the injection of the pressurized gas. The gas outlet is preferably a mechanism that can freely adjust its angle.

  Further, as a method for removing a sizing agent liquid film formed between adjacent sizing agent liquid-impregnated carbon fiber bundles, a member that makes at least a portion directly contact the sizing agent liquid film is interposed between the sizing agent liquid-impregnated carbon fiber bundles. The method of providing can also be used preferably. This member can remove the film | membrane of a sizing agent liquid by positioning at least one part between carbon fiber bundles. At this time, before the member travels through the intermediate point of the traveling path from when the carbon fiber bundle comes out of the liquid surface of the sizing agent solution and comes into contact with the pulling roller (guide roller or nip roller), Arrange so that the film of the sizing solution can be removed. At that time, it is preferable that the member is provided at a position immediately after the carbon fiber bundle is pulled up from the sizing agent solution so as to remove the liquid film as soon as possible.

  The member is not particularly limited as long as it has a structure that can remove the film of the sizing agent solution or suppress the generation itself. For example, as a member for removing the film of the sizing agent liquid, a protrusion (such as a pin-shaped protrusion) between the adjacent sizing agent liquid-impregnated carbon fiber bundles at a position immediately after the carbon fiber bundle is pulled up from the sizing agent liquid Sizing generated between the sizing agent liquid-impregnated carbon fiber bundles by arranging a grooved roller that rotates in the forward or reverse direction with respect to the traveling direction of the carbon fiber bundle, and may be configured as a rod-shaped object. A structure that removes the film of the chemical solution may be used. However, if the member comes into contact with the sizing agent liquid-impregnated carbon fiber bundle traveling on the member or on the left and right of the member, it may cause fluffing or cause fluctuations in yarn width. It is desirable to have a structure and arrangement that do not contact the traveling sizing agent liquid-impregnated carbon fiber bundle.

  The member can have a structure and arrangement as shown in FIGS. 2 and 3, for example. In FIG. 2 (a), (b), the rod-shaped member 8 is arrange | positioned between the adjacent sizing agent liquid impregnation carbon fiber bundle so that it may not contact a sizing agent liquid impregnation carbon fiber bundle. 3A and 3B, the groove top portion 9a of the grooved roller is disposed between adjacent sizing agent liquid-impregnated carbon fiber bundles so that the grooved roller 9 does not contact the sizing agent liquid-impregnated carbon fiber bundle. Is arranged.

(Drying process)
As a method for drying a carbon fiber bundle impregnated with a sizing agent liquid pulled up by a pulling roller, conventionally, a drying method used when applying a sizing agent to a carbon fiber bundle can be used as appropriate, for example, passing through a drying furnace. And a method of drying by bringing a heated heating roller into contact with the carbon fiber bundle.

  In the sizing treatment step of the present invention, the tension applied to the carbon fiber bundle is preferably 0.5 to 5.0 cN / tex. When the tension is 0.5 cN / tex or more, it is possible to easily prevent the convergence of the carbon fiber bundle before impregnating with the sizing solution, and to prevent the fluff caused by vibration and vibration of the running carbon fiber bundle. Occurrence, yarn path fluctuations, and yarn width fluctuations caused by them can be easily prevented. Furthermore, it is possible to easily prevent the sizing agent liquid-impregnated carbon fiber bundle from being widened by the sizing agent liquid-impregnated carbon fiber bundle, and to effectively remove the sizing agent liquid film. Can do. Conversely, when the tension is 5.0 cN / tex or less, it becomes easy to suppress the formation of a film of the sizing agent solution. Furthermore, it is possible to easily prevent the occurrence of single fiber breakage and fluffing due to the application of tension, and the variation in the yarn width of the carbon fiber bundle due to single fiber breakage and fluffing. Moreover, it can prevent easily that it becomes the cause of process troubles, such as the entanglement of single fibers, and the winding of the single fiber around a roller. From the above viewpoint, the tension of the carbon fiber bundle immediately before applying the sizing agent is preferably 0.5 to 5.0 cN / tex, more preferably 1.0 to 4.5 cN / tex, still more preferably. Is 1.5 to 4.0 cN / tex. In the sizing treatment, the present invention can be made more effective by setting the tension of the carbon fiber bundle within the above range.

  Hereinafter, although the manufacturing method of the carbon fiber bundle of this invention is demonstrated more concretely based on an Example, this invention is not limited to these Examples.

Example 1
First, 40 parts by mass of liquid bisphenol A type epoxy resin (made by Japan Epoxy Resin Co., Ltd., trade name: “JER828”) and solid bisphenol A type epoxy resin (made by Japan Epoxy Resin Co., Ltd., trade name: “JER1001”) “) 40 parts by mass and 20 parts by mass of a pluronic surfactant (manufactured by ADEKA, trade name:“ Adeka Pluronic F-88 ”) were mixed to prepare a sizing agent. Thereafter, the sizing agent was diluted with water to prepare an aqueous dispersion of a sizing agent having a solid content of 40% by mass, and further diluted to obtain an aqueous dispersion having a solid content of 5.5% by mass. Used as a chemical solution.

  30 carbon fiber bundles (manufactured by Mitsubishi Rayon Co., Ltd., trade name: “Pyrofil TR 50S”, 15,000 filaments, total fineness 1000 tex, fiber diameter 7 μm) before the sizing agent are applied, and the distance between each carbon fiber bundle is It arranged in parallel so that it might be set to 6 mm, and it was made into the sheet form. After the sizing agent solution is put into the immersion tank 3 shown in FIG. 1, the sheet-like carbon fiber bundle 1 is immersed in the sizing agent solution, the speed is 10 m / min, and the tension applied to the carbon fiber bundle is 2. The carbon fiber bundle was impregnated with the sizing agent solution under the condition of 5 cN / tex.

The yarn path was dipped in the sizing agent liquid in the dipping tank 3, passed through the two dipping rollers 2, and the sizing agent liquid-impregnated carbon fiber bundle was pulled up by the guide roller 5. The distance (hereinafter also referred to as “pull-up distance”) of the traveling path from which the carbon fiber bundle travels from the liquid surface of the sizing agent solution to the guide roller 5 was 50 cm. Further, the injection nozzle 4 is set so that the pressurized air is injected to a position where the carbon fiber bundle comes out from the liquid level of the sizing agent liquid in the immersion tank 3 (position 0 cm from the liquid level in the running path of the carbon fiber bundle). Arranged. Hereinafter, the position where the injected pressurized air contacts the carbon fiber bundle, that is, the position of the collision portion between the pressurized air and the carbon fiber bundle may be referred to as “removal operation execution position”. The flow rate at the position where the pressurized air removal operation was performed was 5.0 m / sec. The distance between the injection nozzle 4 and the carbon fiber bundle was 5 cm.
The carbon fiber bundle after passing through the guide roller 5 is sandwiched between a pair of nip rolls 6, drained, dried by bringing it into contact with a heating roller 7 heated to 140 ° C. for 90 seconds, and a carbon to which a sizing agent is adhered. A fiber bundle was obtained. The carbon fiber bundle after the drying treatment was wound up on a bobbin.

  The above-described treatment of the carbon fiber bundle was performed continuously for 2 hours, and the presence or absence of the formation of a sizing agent liquid film between adjacent sizing agent liquid-impregnated carbon fiber bundles was visually observed. A film of sizing agent liquid was not formed after the injection of pressurized air was started. Therefore, the carbon fiber bundle with the liquid film remaining did not reach the position 25 cm from the liquid surface, which is the middle point of the pulling distance, or the guide roller 5. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. The yarn width of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after the drying treatment) was measured by the following method. The results are shown in Example 1 in Table 1.

(Measurement of yarn width of carbon fiber bundle with sizing agent attached)
Using a CCD camera (manufactured by Keyence Corporation, product name: CV-020 (350,000 pixel 1/3 type black and white, square lattice CCD camera) and a controller (manufactured by Keyence Corporation, product name: CV-2000) The width of the carbon fiber bundle to which the sizing agent was attached was measured, and the image was taken with a maximum field-of-view range of 150 mm, an electronic shutter speed of 1/100 second, and the dimensions were measured in advance using the controller's edge width measurement mode. After calibrating with the test piece, the yarn width of the carbon fiber bundle to which the sizing agent was adhered was measured.

  Specifically, a carbon fiber bundle wound around a bobbin after drying processing is supplied from a position 2 m away from a free roller (aluminum alloy, diameter: 200 mm) at a tension of about 2.0 cN / tex. The carbon fiber bundle was run at a speed of about 10 m / min. The yarn width was measured by imaging the yarn width near the center of the holding angle of the carbon fiber bundle on the free roll. Measurements were made at intervals of about 40 mm, and continuous measurements were made 3500 times or more. The measurement is performed on all of the obtained carbon fiber bundles (those wound on a bobbin), and the measurement results are taken into mathematical software in a computer connected to CV-2000, and the coefficient of variation CV (%) is calculated. The results of measuring the yarn width of the carbon fiber bundle to which the sizing agent was attached are shown in Example 1 of Table 1. In addition, it means that the yarn width of the carbon fiber bundle is uniform as the CV value (%) is small.

(Example 2)
The removal operation execution position in the traveling path of the carbon fiber bundle of the injection nozzle 4 is the same as that of Example 1 except that the position where the carbon fiber bundle comes out of the surface of the sizing agent liquid in the immersion tank 3 is 3 cm. The carbon fiber bundle was processed by the method of and evaluated. Immediately after the carbon fiber bundle came out from the liquid level of the sizing agent solution in the immersion tank 3, a film of the sizing agent solution was formed, but all of the film was removed at the collision part (removal operation execution position) of the pressurized air. Furthermore, the carbon fiber bundle with the liquid film remaining did not reach the position 25 cm from the liquid surface, which is the middle point of the pulling distance, or the guide roller 5. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. The results of yarn width measurement of the obtained carbon fiber bundle (carbon fiber bundle wound around a bobbin after the drying treatment) to which the sizing agent is adhered are shown in Example 2 of Table 1.

(Example 3)
The removal operation execution position in the traveling path of the carbon fiber bundle of the injection nozzle 4 is the same as that of Example 1 except that the position of the carbon fiber bundle is 20 cm from the position where the liquid surface of the sizing agent liquid in the immersion tank 3 comes out. The carbon fiber bundle was processed by the method of and evaluated. Immediately after the carbon fiber bundle came out from the liquid level of the sizing agent solution in the immersion tank 3, a film of the sizing agent solution was formed, but all of the film was removed at the collision part of the pressurized air. The carbon fiber bundle with the liquid film remaining did not reach the position 25 cm from the liquid surface as the intermediate point or the guide roller 5. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. Table 3 shows the results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after the drying treatment).

Example 4
The carbon fiber bundle was treated and evaluated in the same manner as in Example 2 except that the tension applied to the carbon fiber bundle was 1.2 cN / tex. Although the frequency of the sizing agent liquid film formed immediately after the carbon fiber bundle emerges from the liquid surface of the sizing agent liquid in the immersion tank 3 was higher than that in Example 2, it was all in the collision part of the pressurized air. Since it was removed, the carbon fiber bundle with the liquid film remaining did not reach the position 25 cm from the liquid surface, which is the middle point of the pulling distance, or the guide roller 5. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. Table 4 shows the results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after drying treatment).

(Example 5)
The carbon fiber bundle was treated and evaluated in the same manner as in Example 2 except that the tension applied to the carbon fiber bundle was 5.0 cN / tex. Although the frequency of forming the film of the sizing agent liquid immediately after the carbon fiber bundle came out from the liquid surface of the sizing agent liquid in the dipping tank 3 was smaller than that in Example 2, it did not become zero. Since the film of the sizing agent liquid was completely removed at the collision part of the pressurized air, the carbon fiber bundle with the liquid film remaining at the position 25 cm from the liquid surface, which is the middle point of the pulling distance, to the guide roller 5 Never reached. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. The results of yarn width measurement of the obtained carbon fiber bundle (carbon fiber bundle wound around the bobbin after the drying treatment) to which the sizing agent is adhered are shown in Example 5 of Table 1.

(Example 6)
The number of carbon fiber bundles was changed to 15, and the carbon fiber bundles were processed in the same manner as in Example 2 except that they were arranged in parallel so that the gap between the carbon fiber bundles was 12 mm. And evaluated. Although the frequency of forming the film of the sizing agent liquid immediately after the carbon fiber bundle came out from the liquid surface of the sizing agent liquid in the dipping tank 3 was smaller than that in Example 2, it did not become zero. Since the film of the sizing agent liquid was completely removed at the collision part of the pressurized air, the carbon fiber bundle was left with the liquid film remaining at the position 25 cm from the liquid surface, which is the middle point of the pulling distance, and the guide roller 5. Never reached. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. Table 6 shows the results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after the drying treatment).

(Example 7)
As shown in FIGS. 2 (a) and 2 (b), the carbon fiber bundle is not contacted between the carbon fiber bundles at a position of 5 cm from the position where the carbon fiber bundles have come out from the liquid surface of the sizing agent liquid in the immersion tank 3. The carbon fiber bundles were processed and evaluated in the same manner as in Example 1 except that the bar-shaped member 8 was disposed. In Example 7, pressurized air is not injected. Immediately after the carbon fiber bundle comes out from the surface of the sizing agent liquid in the dipping tank 3, a film of the sizing agent liquid is formed. When the film of the sizing agent liquid comes into contact with the rod-shaped member 8, the sizing is performed. Since all of the film of the chemical solution was removed, the carbon fiber bundle did not reach while leaving the liquid film at a position 25 cm from the liquid surface, which is the middle point of the pulling distance, and the guide roller 5. Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. Table 7 shows the results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after the drying treatment).

(Example 8)
As shown in FIGS. 3 (a) and 3 (b), a grooved roller is placed at a position 10 cm from the position where the carbon fiber bundle comes out from the surface of the sizing agent liquid in the dipping tank 3 so as not to contact the carbon fiber bundle. A carbon fiber bundle was treated and evaluated in the same manner as in Example 1 except that 9 was provided. In Example 8, the injection of pressurized air is not performed. The grooved roller 9 was a drive roller that rotated in the direction opposite to the traveling direction of the carbon fiber bundle. Immediately after the carbon fiber bundle comes out from the surface of the sizing agent liquid in the dipping tank 3, a film of the sizing agent liquid is formed, but when the film of the sizing agent liquid contacts the groove top 9a of the grooved roller. Since all the film of the sizing agent liquid was removed, the carbon fiber bundle did not reach while leaving the liquid film at the position 25 cm from the liquid surface, which is the middle point of the pulling distance, and the guide roller 5. . Further, the yarn width of the carbon fiber bundle on the guide roller 5 was uniform. Further, no fluff was generated during the continuous treatment for 2 hours, and the sizing solution was not dried or fixed on the guide roller 5. Table 8 shows the results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent was adhered (carbon fiber bundle wound on a bobbin after drying treatment).

(Comparative Example 1)
The carbon fiber bundle was treated and evaluated in the same manner as in Example 1 except that pressurized air was not jetted onto the carbon fiber bundle. Immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid in the immersion tank 3, a film of the sizing agent liquid is formed and reaches a position of 25 cm from the liquid surface which is an intermediate point of the pulling distance, In some cases, a film of the sizing agent liquid remained until just before contacting the guide roller 5. The film of the sizing agent solution disappeared simultaneously with the contact with the guide roller 5, but the carbon fiber bundle in contact with the guide roller 5 in such a state can be confirmed to have a widened yarn width on the guide roller 5. In comparison, the yarn widths of the 30 carbon fiber bundles processed in parallel were also clearly non-uniform. During the continuous treatment for 2 hours, no fluff was generated, and the sizing solution was not dried or fixed on the guide roller 5. The results of yarn width measurement of the obtained carbon fiber bundle (carbon fiber bundle wound on a bobbin after drying treatment) to which the sizing agent is adhered are shown in Comparative Example 1 in Table 1.

(Comparative Example 2)
The carbon fiber bundle is treated in the same manner as in Example 1 except that the arrangement of the injection nozzle 4 is 40 cm from the position where the carbon fiber bundle comes out of the liquid level of the sizing agent liquid in the immersion tank 3. evaluated. Immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid in the immersion tank 3, a film of the sizing agent liquid may be formed and reach a position of 25 cm from the liquid surface that is the middle point of the lifting distance. It was. Since the film of the sizing agent liquid was completely removed at the collision part of the pressurized air, the carbon fiber bundle with the liquid film remaining on the guide roller 5 did not reach, but it was generated by the film of the sizing agent liquid. The widening of the yarn width of the carbon fiber bundle was not eliminated, and the widening of the yarn width could be confirmed on the guide roller 5. Compared with Example 1, the yarn width of the 30 carbon fiber bundles processed in parallel was not uniform. Met. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. During the continuous treatment for 2 hours, no fluff was generated, and the sizing solution was not dried or fixed on the guide roller 5. The results of yarn width measurement of the obtained carbon fiber bundle to which the sizing agent is adhered (carbon fiber bundle wound on a bobbin after drying treatment) are shown in Comparative Example 2 in Table 1.

(Comparative Example 3)
After the injection nozzle 4 and the guide roller 5 are arranged as shown in FIG. 4 and the carbon fiber bundle is pulled up by the guide roller 5, the carbon fiber bundle on the guide roller 5 is tangential to the direction opposite to the pulling direction. The carbon fiber bundles were treated and evaluated in the same manner as in Example 1 except that the flow velocity at the collision part was 30.0 m / second and pressurized air was injected. Immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid in the immersion tank 3, a film of the sizing agent liquid may be formed and reach a position of 25 cm from the liquid surface that is the middle point of the lifting distance. It was. Although the carbon fiber bundle with the liquid film remaining on the guide roller 5 did not reach, the widening of the yarn width of the carbon fiber bundle caused by the film of the sizing agent liquid was not eliminated, and on the guide roller 5 The widening of the yarn width was confirmed, and compared with Example 1, the yarn widths of the 30 carbon fiber bundles processed in parallel were also non-uniform. In addition, even if pressurized air was injected, the liquid level of the sizing agent liquid in the immersion tank 3 was only slightly shaken, and the sizing agent liquid was not scattered and contaminated the surroundings. One hour after the start of the injection of the pressurized air, the sizing agent liquid was dried and fixed on the guide roller 5 and the single yarn was wound by this, so the quality of the obtained carbon fiber bundle was low. It was a thing. The results of yarn width measurement of the obtained carbon fiber bundle (carbon fiber bundle wound around the bobbin after the drying treatment) to which the sizing agent is adhered are shown in Comparative Example 3 in Table 1.

(Comparative Example 4)
The carbon fiber bundle was treated and evaluated in the same manner as in Comparative Example 3 except that the distance from the carbon fiber bundle coming out of the sizing agent liquid to the guide roller 5 was 20 cm. Immediately after the start of injection of pressurized air, the liquid level of the sizing agent liquid in the dipping tank 3 was greatly swollen and the sizing agent was scattered around, so the experiment was stopped.

(Comparative Example 5)
The injection nozzle 4 is arranged as shown in FIG. 5, the carbon fiber bundle is pulled up by the guide roller 5, and then the pressurized air is jetted onto the carbon fiber bundle on the guide roller 5. The carbon fiber bundle was processed by the method of and evaluated. The film of the sizing agent liquid is formed immediately after the carbon fiber bundle comes out from the liquid level of the sizing agent liquid in the immersion tank 3, and reaches the position of 25 cm from the liquid level that is the middle point of the lifting distance. In some cases, a film of the sizing agent liquid remains until just before contact with the guide roller 5. The film of the sizing agent solution disappeared when it contacted the guide roller 5, but the carbon fiber bundle that contacted the guide roller 5 in such a state increased the yarn width on the guide roller 5 even after the pressurized air was jetted. As compared with Example 1, the yarn widths of the 30 carbon fiber bundles processed in parallel were also non-uniform. In addition, since the sizing agent solution was dried and fixed on the guide roller 5 and the single yarn was wound by this, the quality of the obtained carbon fiber bundle was low. The results of measuring the yarn width of the obtained carbon fiber bundle are shown in Comparative Example 5 in Table 1.

(Comparative Example 6)
The injection nozzle 4 is disposed as shown in FIG. 6, and the carbon fiber bundle is processed in the same manner as in Example 1 except that pressurized air is injected onto the carbon fiber bundle after passing through the guide roller 5. evaluated. The film of the sizing agent liquid is formed immediately after the carbon fiber bundle comes out from the liquid level of the sizing agent liquid in the immersion tank 3, and reaches the position of 25 cm from the liquid level that is the middle point of the lifting distance. In some cases, a film of the sizing agent liquid remains until just before contact with the guide roller 5. The film of the sizing solution disappeared when it contacted the guide roller 5, but the carbon fiber bundle that was in contact with the guide roller 5 in such a state could confirm the widening of the yarn width on the guide roller 5, and compared with Example 1. Thus, the yarn widths of the 30 carbon fiber bundles processed in parallel were also non-uniform. During the continuous treatment for 2 hours, no fluff was generated, and the sizing solution was not dried or fixed on the guide roller 5. The results of measuring the yarn width of the obtained carbon fiber bundle are shown in Comparative Example 6 in Table 1.

(Comparative Example 7)
The carbon fiber bundle was processed and evaluated in the same manner as in Comparative Example 1 except that the tension applied to the carbon fiber bundle was 6.0 cN / tex. Immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent solution in the immersion tank 3, the film forming frequency of the sizing agent solution is less than that of the comparative example 1, but it does not become zero, and the lifting distance of In some cases, it reached a position of 25 cm from the liquid level as an intermediate point. The carbon fiber bundle never reached the guide roller 5 while leaving the liquid film, but the widening of the yarn width of the carbon fiber bundle caused by the film of the sizing agent liquid was not eliminated, and on the guide roller 5 The widening of the yarn width could be confirmed, and the yarn widths of the 30 carbon fiber bundles were not uniform as compared with Example 1. During continuous processing for 2 hours, fluff was always generated in the carbon fiber bundle, and the guide roller 5, the draining roller 6 and the drying roll 7 were frequently wound with a single yarn, so the quality of the obtained carbon fiber bundle was low. It was a thing. Note that the sizing agent liquid was not dried or adhered to the guide roller 5. The results of measuring the yarn width of the obtained carbon fiber bundle are shown in Comparative Example 7 in Table 1.

(Comparative Example 8)
As shown in FIG. 7, a flat roller 5 a that rotates in contact with the carbon fiber bundle was disposed at a position 10 cm from the position where the carbon fiber bundle came out from the surface of the sizing agent solution in the immersion tank 3. That is, in Comparative Example 8, the carbon fiber bundle was pulled up by two rollers, the flat roller 5a and the guide roller 5 provided at a position 50 cm from the liquid surface of the sizing agent liquid, as in the other examples. For this reason, the pulling distance of Comparative Example 8 is a distance from the liquid level to the flat roller 5a that is the first pulling roller, and is 10 cm. Except for the installation of the flat roller 5a, the carbon fiber bundle was processed and evaluated in the same manner as in Example 1. In Comparative Example 8, pressurized air is not injected. The flat roller 5a was a free roller. Immediately after the carbon fiber bundle comes out from the liquid surface of the sizing agent liquid in the immersion tank 3, a film of the sizing agent liquid is formed and reaches a position of 5 cm from the liquid surface which is an intermediate point of the lifting distance. In some cases, a film of the sizing agent liquid remains until just before contacting the guide roller 5a. The film of the sizing agent solution disappeared at the same time as it contacted the flat roller 5a. However, the carbon fiber bundle that contacted the flat roller 5a in such a state was confirmed to be widened on the flat roller 5a and the guide roller 5 as well. Compared to Example 1, the yarn widths of the 30 carbon fiber bundles processed in parallel were also clearly non-uniform. During the continuous treatment for 2 hours, no fluff was generated, and neither drying nor fixing of the sizing agent liquid was observed on the flat roller 5a or the guide roller 5. The results of yarn width measurement of the obtained carbon fiber bundle (carbon fiber bundle wound around the bobbin after the drying treatment) to which the sizing agent is adhered are shown in Comparative Example 8 in Table 1.

  In the production method of the present invention, a plurality of parallel running carbon fiber bundles are immersed in the sizing agent solution, and then immersed in the sizing agent solution via a pulling roller disposed above the liquid level of the sizing agent solution. It includes a sizing process step of performing a drying process after pulling up the plurality of carbon fiber bundles.

  Further, in the present invention, when sizing a plurality of carbon fiber bundles, the sizing agent liquid-impregnated carbon fiber bundle is intermediate in the traveling path from when the sizing agent liquid-impregnated carbon fiber bundle exits the liquid surface until it comes into contact with the pulling roller. Before traveling on the spot, the film of the sizing agent liquid formed between adjacent sizing agent liquid-impregnated carbon fiber bundles is removed, and then the sizing agent liquid-impregnated carbon fiber bundles are dried. That is, while the carbon fiber bundle does not have a film of the sizing agent liquid, the carbon fiber bundle travels in the middle of the traveling path of the carbon fiber bundle between the liquid surface of the sizing agent and the pulling roller, and does not have this film. In the state, it is supplied to the lifting roller. For this reason, compared with the conventional manufacturing method, the widening of the sizing agent liquid-impregnated carbon fiber bundle caused by the sizing agent liquid film can be eliminated, and the variation in the yarn width in the fiber axis direction in the sized carbon fiber bundle is reduced. Furthermore, it is possible to make the yarn width uniform among a plurality of carbon fiber bundles that are processed in parallel.

1 Carbon fiber bundle 2 Immersion roller 3 Sizing agent bath (immersion bath)
4 Injection nozzle 5 Guide roller (lifting roller)
5a Flat roller (lifting roller)
6 Draining roller (nip roller)
7 Heating roller 8 Bar-shaped member 9 Grooved roller 9a Groove top of grooved roller

Claims (5)

After immersing a plurality of carbon fiber bundles running in parallel in a sizing agent solution, the plurality of carbon fiber bundles immersed in the sizing agent solution via a pulling roller disposed above the liquid level of the sizing agent solution A method for producing a carbon fiber bundle impregnated with a sizing agent solution including a sizing treatment step of performing a drying process after pulling up the carbon fiber bundle,
In the sizing treatment step, the sizing is performed before the plurality of carbon fiber bundles travel on the intermediate point of the traveling path from the time when the carbon fiber bundle comes out of the liquid surface of the sizing agent solution and comes into contact with the pulling roller. A method for producing a carbon fiber bundle impregnated with a sizing agent liquid, wherein a film of the sizing agent liquid formed between adjacent carbon fiber bundles of the plurality of carbon fiber bundles after coming out of the liquid surface of the agent liquid is removed.   In the sizing treatment step, the sizing agent liquid is injected by injecting a pressurized gas onto a film formed between adjacent carbon fiber bundles among the plurality of carbon fiber bundles immersed in the sizing agent liquid. The method for producing a carbon fiber bundle impregnated with a sizing agent solution according to claim 1, wherein the film is removed.   The method for producing a sizing-agent-impregnated carbon fiber bundle according to claim 2, wherein the pressurized gas is sprayed using a spray nozzle, and the spray nozzle is disposed so that the pressurized gas does not directly hit the pulling roller.   In the sizing treatment step, a member for removing a film of the sizing agent liquid is in contact with the plurality of carbon fiber bundles immersed in the sizing agent liquid between the liquid level of the sizing agent liquid and the pulling roller. The film of the sizing agent liquid is disposed by placing at least a part of the member between adjacent carbon fiber bundles of the plurality of carbon fiber bundles immersed in the sizing agent liquid. The method for producing a carbon fiber bundle impregnated with a sizing agent solution according to claim 1, wherein the carbon fiber bundle is removed.   The sizing agent liquid-impregnated carbon fiber according to any one of claims 1 to 4, wherein in the sizing treatment step, a tension applied to the plurality of carbon fiber bundles is 0.5 cN / tex or more and 5.0 cN / tex or less. A method of manufacturing a bundle.

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