JPWO2019012856A1 - Method for producing sizing agent-added carbon fiber bundle - Google Patents

Abstract

  A manufacturing method of sizing agent imparting carbon fiber bundle which obtains a sizing agent imparting carbon fiber bundle through a drying process after a sizing agent applying step of immersing a plurality of carbon fiber bundles (1) running in parallel in a sizing agent liquid tank (4) Carbon fiber bundle (1) is immersed in the sizing agent liquid tank (4) to solve the problem of winding around by the sizing agent liquid fixing to the guide roller (3), and the carbon fiber bundle (1) The surface adhesion of the guide roller on the first guide roller (3) after leaving the liquid surface of the tank (4) is 0.2 N / cm 2 or less.

Description

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

  Carbon fiber bundles are widely used in aerospace and space applications, sports leisure applications, general industrial applications such as automobiles and windmills, etc. because they have excellent mechanical properties, in particular, high specific strength and high specific modulus. In recent years, customers who use carbon fiber bundles are strongly in demand for higher quality and cost reduction.

  The carbon fiber bundle generally has a low elongation and a brittle property, and is prone to fluff due to contact with a roller, abrasion with a yarn path guide, and the like in the subsequent processing steps, sometimes causing yarn breakage. Therefore, by providing various sizing agents to the carbon fiber bundle, the handling property is improved, and the convergence and abrasion resistance of the carbon fiber bundle are improved, and the fluff generation of the carbon fiber bundle is suppressed. It is common to maintain quality.

  As a sizing agent application method to a carbon fiber bundle, there are various methods such as a spray injection method, a dropping method, and a kiss roller method. The dip system in which the carbon fiber bundle is immersed in a sizing agent liquid tank is preferable from the efficiency that can be simultaneously and easily imparted to the multifilament yarn. However, if the carbon fiber bundle is increased in filament formation or the production speed is increased for cost reduction, the amount of sizing agent liquid adhering to the carbon fiber bundle and carried out of the sizing agent liquid tank increases, and The amount of sizing agent liquid adhering to the guide roller leading to the subsequent drying step of the sizing agent application step also increases. Then, on the surface of the guide roller, the sizing agent liquid is dried to generate a resin reservoir and the viscosity is increased. When the carbon fiber bundle comes in contact with the resin reservoir, fluff is generated, and sometimes the carbon fiber bundle is wound around the guide roller, resulting in a problem that the process passability is lowered. In addition, when the distance between adjacent carbon fiber bundles is narrowed for multifilamentization, a film of a sizing agent solution is likely to be generated between adjacent yarns. When the liquid film is dried as it is, adhesion spots of the sizing agent solution are generated. Further, the surface tension of the sizing agent solution causes adjacent carbon fiber bundles to stick to each other, which tends to cause a problem of separation failure.

  As an improvement technique, in Patent Documents 1 and 2, after the carbon fiber bundle exits the liquid surface of the sizing agent liquid tank, a yarn of carbon fiber bundle is ejected by injecting pressurized gas toward the carbon fiber bundle. A method is disclosed for removing a liquid film consisting of a sizing agent generated in the meantime.

  In Patent Document 3, a carbon fiber bundle is held by at least a pair of nip rolls to remove an excess sizing agent liquid impregnated in the carbon fiber bundle, and a sizing agent liquid is applied to the surface of the nip roll to obtain a sizing agent liquid. Methods are disclosed to prevent the drying of In addition, according to Patent Document 4, after a sizing process is performed on a carbon fiber bundle in an untwisted state, a wiping process can be performed using a wiping cloth as a method for producing a carbon fiber bundle having excellent spreadability, in which drying processing is performed using a hot roll. Discloses a method for removing excess sizing agent liquid from a hot roll by pressing it.

JP, 2013-23785, A JP-A-7-145549 JP 2011-256486 A Unexamined-Japanese-Patent No. 1-292038

  However, in the methods of Patent Documents 1 and 2, even though the liquid film between the carbon fiber bundle yarns can be removed, the sizing agent liquid still adheres to the carbon fiber bundle, and the sizing agent liquid is transferred to the guide roller surface. As a result, there was a problem that resin accumulation occurred. Further, in the method of Patent Document 3, since the fragile carbon fiber bundle is held by the nip roll, there is a problem that fuzzing occurs and the process passability decreases. In the method of Patent Document 4, since excess sizing agent liquid adhering to the hot roll is removed with a wiping cloth, resin accumulation due to drying of the sizing agent liquid with the hot roll itself is suppressed, but before the hot roll, The sizing agent solution is easily dried on the first guide roller after the sizing agent application process, and the single yarn of the carbon fiber bundle is taken up in the resin reservoir generated at the time of drying the sizing agent solution, so that fuzzing and winding occur was there.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and in a method for producing a carbon fiber bundle to which a sizing agent solution is applied, carbon fibers by drying of a sizing agent solution by a guide roller and resin reservoir It is an object of the present invention to provide a method for producing a carbon fiber bundle provided with a sizing agent, which can solve the problem of bundle winding and fuzzing.

In order to achieve the above object, the present invention has the following configuration. That is,
After the sizing agent application step of immersing a plurality of carbon fiber bundles running in parallel in the sizing agent liquid tank, the carbon fiber bundle is subjected to a drying step to obtain a sizing agent applied carbon fiber bundle through a drying step. Sizing agent-imparted carbon fiber bundle in which the guide roller surface adhesion degree in the first guide roller after immersion in the sizing agent liquid tank and the carbon fiber bundle comes out of the liquid surface of the sizing agent liquid tank is 0.2 N / cm ² or less Manufacturing method.

  According to the present invention, in the method for producing a sizing agent-added carbon fiber bundle to which a sizing agent solution has been applied, high-quality carbon fiber bundles with few fluffs can be prevented by preventing drying and resin accumulation of the sizing agent solution at a guide roller. You can get Moreover, winding of the carbon fiber bundle to a guide roller can also be suppressed, and it is excellent also in process passability.

It is a schematic block diagram which shows an example of the sizing provision process in this invention. It is a schematic block diagram which shows another example of the sizing provision process in this invention. It is a schematic block diagram which shows another example of the sizing provision process in this invention. It is a schematic block diagram which shows another example of the sizing provision process in this invention. It is a figure which shows the calculation method of the force which starts the carbon fiber bundle. It is a schematic block diagram which shows an example of the conventional sizing provision process.

The method for producing a sizing agent-imparted carbon fiber bundle according to the present invention comprises a sizing agent application step of immersing a plurality of carbon fiber bundles running in parallel in a sizing agent liquid tank and a drying step provided after that, the sizing agent In this case, the carbon fiber bundle is immersed in the sizing agent liquid tank, and the guide roller surface of the first guide roller after the carbon fiber bundle comes out of the liquid surface of the sizing agent liquid tank. The adhesion degree is 0.2 N / cm ² or less.

  Hereinafter, the method for producing the sizing agent-added carbon fiber bundle of the present invention will be described in detail.

  The carbon fiber bundle used in the present invention may be obtained from any raw material such as pitch type, rayon type and polyacrylonitrile type, but from the viewpoint of quality and productivity, polyacrylonitrile type carbon fiber bundle is preferable. preferable. Moreover, there is no limitation in particular also about the form of the carbon fiber bundle used for this invention, For example, the bundle of the carbon fiber whose single yarn diameter is 3 micrometers-10 micrometers can be used. Moreover, there is no limitation in particular also about the number of single yarns of the carbon fiber which comprises a carbon fiber bundle, For example, it can be set as 1000-100000. However, the effect of the present invention is likely to be effective in the case of a carbon fiber bundle having a relatively large number of single yarns and carrying a large amount of sizing agent liquid from the sizing agent liquid tank.

  The polyacrylonitrile-based carbon fiber bundle preferably used in the present invention can be obtained by flameproofing, pre-carbonization or carbonization of the polyacrylonitrile-based precursor fiber bundle by a known method, and is not particularly limited. Absent. Flameproofing can be carried out at 200 to 300 ° C. in an oxidizing atmosphere. Air is preferable as an oxidizing gas in the oxidization from the economical point of view. Subsequently, it can be precarbonized in a precarbonizing furnace at a maximum temperature of 300 to 1000 ° C. in an inert atmosphere. Furthermore, carbon fiber bundles can be obtained by carbonizing the pre-carbonized fiber bundles at a maximum temperature of 1200 to 2000 ° C. The carbon fiber bundle may be further graphitized at a temperature of 2000 to 3000 ° C., if necessary. Although precarbonization, carbonization and graphitization are performed in an inert atmosphere, examples of the inert gas used include nitrogen, argon and xenon, and nitrogen is preferably used from the economical viewpoint.

  In addition, when forming a carbon fiber reinforced composite material, electrolytic oxidation treatment in an electrolytic solution or oxidation in the gas phase or liquid phase is performed in order to easily improve the affinity and adhesion between the carbon fiber bundle and the matrix resin. It is preferable to surface-treat a carbon fiber bundle, such as treatment. As the electrolytic solution, either an acidic aqueous solution or an alkaline aqueous solution can be used, but as the acidic aqueous solution, sulfuric acid or nitric acid exhibiting strong acidity is preferable, and as the alkaline aqueous solution, ammonium carbonate, ammonium hydrogencarbonate, ammonium bicarbonate etc. An aqueous solution of inorganic alkali is preferably used.

  As a sizing agent solution used in the present invention, a solution obtained by dispersing or dissolving a sizing agent in water or an organic solvent such as acetone can be used, but from the viewpoint of uniform application to carbon fiber bundles and safety, It is preferable that it is an aqueous dispersion or an aqueous solution in which the sizing agent is dispersed or dissolved in water. In addition, the said sizing agent can be used according to the matrix resin used by high-order processing from what is well-known in the field | area of a carbon fiber. The sizing agent can include the main agent and various additives described later, and can be made of, for example, the main agent and an emulsifier. By drying the carbon fiber bundle impregnated with the sizing agent solution, it is possible to obtain a sizing agent-added carbon fiber bundle in which the sizing agent is attached to the surface of the carbon fiber bundle.

  Although the type of sizing agent used in the present invention is not particularly limited, the present invention is directed to a sizing agent liquid which is easily dried on a guide roller to generate a resin reservoir and form a sticky deposit. It is effective. When the thermosetting resin is contained in the component of the sizing agent, the main component of the sizing agent is epoxy resin, epoxy-modified polyurethane resin, polyester resin, phenol resin, polyamide resin, polyurethane resin, polycarbonate resin, polyetherimide resin, polyamide An imide resin, a polyimide resin, a bismaleimide resin, a urethane modified epoxy resin, a polyvinyl alcohol resin, a polyvinyl pyrrolidone resin, a polyether sulfone resin, etc., or two or more of these may be used in combination. When the component of the sizing agent contains a thermoplastic resin, the main component of sizing is polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene, polyethylene terephthalate, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyethylene imine, polyacrylamide, polyphenylene ether, Polyacetal, polybutylene terephthalate, polyphenylene sulfide, polyetheretherketone, elastomeric cellulose compound, acrylic resin, polyurethane resin, polyamide resin, fluorocarbon resin, ABS resin and liquid crystal polymer, sodium hydroxide of styrene-maleic anhydride copolymer (partial )) Those containing at least one or more components selected from the group of neutralized products may be used.

  Moreover, since these organic compounds are often insoluble in water, surfactants may be added to form emulsions. The type of surfactant is not particularly limited, but it is preferable to use a nonionic surfactant. As nonionic surfactants, polyoxyethylene alkyl ether, single linear polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sterol ether, polyoxyethylene sterol ether, Polyoxyethylene lanolin derivatives, ethylene oxide derivatives of alkylphenol formalin condensates, ether type such as polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil and hydrogenated castor oil, polyoxyethylene sorbitan Ether ester type such as fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester Ether, ester such as polyglycerol fatty acid ester and the like, are used in combination of several kinds from one from among them.

  In dilution of the sizing solution, it is preferable to use economical and safe water. When the sizing agent solution is used as a water dispersion, the concentration is adjusted so that water is present as a continuous phase, but the tank concentration of the sizing agent solution is adjusted so that the amount of adhesion to the carbon fiber bundle is a desired amount. Is generally diluted to about 0.1 to 10% by mass and impregnated into a carbon fiber bundle. When water is added to the sizing solution to dilute the sizing solution to a desired bath concentration, the sizing solution may be diluted at one time depending on the composition concentration of the main component other than water. And may be diluted in multiple times. The sizing agent liquid may contain various additives such as a surfactant, a leveling agent, and an emulsifier, in addition to the above-mentioned main component.

In the resin reservoir of the sizing agent liquid in the guide roller after passing the sizing agent application process in the traveling direction of the carbon fiber bundle, the sizing agent liquid carried out from the sizing agent liquid tank by the carbon fiber bundle is transferred to the guide roller and retained. It is caused by doing. When the resin of the sizing solution is dried by the guide roller and a resin reservoir is generated, the traveling carbon fiber bundle comes into contact with the resin reservoir on the guide roller, and the degree of adhesion when the carbon fiber bundle is separated from the resin reservoir Becomes large, and fluff and winding occur. In the method for producing a carbon fiber bundle of the present invention, the adhesion degree of the guide roller on the first guide roller after the carbon fiber bundle leaves the liquid surface of the sizing agent solution tank is 0.2 N / cm ² or less, preferably 0. By setting it as 1 N / cm < ² > or less, drying of the sizing agent liquid in the said guide roller can be prevented, and the resin pool of a sizing agent can be prevented. When the degree of surface adhesion of the guide roller is greater than 0.2 N / cm ² , fluff may be generated from the carbon fiber bundle, sometimes causing a winding problem. Guide roller surface tackiness is 0.20 N / cm ² or less, more preferably kept below 0.10 N / cm ^2. The lower the surface adhesion of the guide roller, the better the quality of the carbon fiber bundle. However, the present invention prevents the drying of the sizing agent liquid at the guide roller and the accumulation of resin, thereby providing high quality with few fluffs. The purpose is to obtain a carbon fiber bundle, and the carbon fiber bundle needs to be provided with a sizing agent. And, since the sizing agent liquid is dried to a certain extent on the guide roller to form a resin reservoir, tackiness occurs. Therefore, it is preferable that the surface adhesion degree in a guide roller does not become substantially zero, and the minimum of guide roller surface adhesion degree is 0.01 N / cm < ² >.

Here, the guide roller surface adhesion degree is calculated by the following equation.
Guide roller surface adhesion (N / cm ² ) = moving force of carbon fiber bundle / guide roller surface contact area of carbon fiber bundle.

  A method of calculating the moving force of the carbon fiber bundle will be described with reference to FIG. In addition, it is considered that it is a value under manufacture by measuring as follows in less than 10 minutes after stopping the manufacturing equipment of the carbon fiber bundle at the time of long-term stable production, as the power which carbon fiber starts to move.

  First, after fixing the guide roller 3 to which the sizing agent liquid is attached so as not to rotate, the carbon fiber bundle 1 dried completely before applying the sizing agent is dropped from the uppermost point of the guide roller 3 to contact angle Set at 180 °. Next, a ring is formed at one end of the carbon fiber bundle 1 set in the circumferential direction of the guide roller 3, a hook is attached to the tip of the load measuring instrument 7, and the hook is hooked on the ring of carbon fiber bundle. Although a load measuring device is not particularly limited, a push-pull gauge capable of measuring an instantaneous maximum load is preferable. The carbon fiber bundle is slowly pulled by a load measuring device, and the maximum force immediately before the carbon fiber bundle 1 moves on the surface of the guide roller 3 is defined as the carbon fiber moving force (unit: Newton).

  The term "long-term stable production" refers to industrially stable long-term (24 hours or more) continuous production without fuzz or winding. In addition, the stop of the carbon fiber bundle manufacturing equipment is the time when the manufacturing equipment of the process including the guide roller from the sizing agent liquid tank of the carbon fiber bundle is stopped. The guide roller can be fixed for the first time by stopping the carbon fiber bundle manufacturing equipment, and the moving force of the carbon fiber bundle can be measured.

  The moving force of the carbon fiber bundle can be adjusted by adjusting the degree of dryness of the sizing agent solution adhering to the surface of the guide roller or changing the material of the guide roller.

  In addition, the surface contact area of the carbon fiber bundle with the guide roller surface is the circumferential length and the carbon fiber bundle along the circumferential direction of the surface of the guide roller from the point where the carbon fiber bundle starts contacting on the guide roller to the point of leaving the guide roller. It is calculated by the product of the yarn width of The surface contact area can be changed by changing the contact circumferential length of the carbon fiber on the guide roller or the number of filaments of the carbon fiber bundle.

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

FIG. 1 is a schematic configuration view showing an example of a sizing application process in the present invention. In the embodiment shown in FIG. 1, the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 by passing through the immersion roller 2, and it comes out of the liquid surface by the guide roller 3 and is dried in the next step of the sizing application step. Led. In such an embodiment, the sizing agent liquid adheres to the guide roller 3 by passing the carbon fiber bundle 1 to which the sizing agent liquid is applied. Therefore, in order to prevent the sizing agent liquid adhering to the guide roller 3 from sticking, the guide roller 3 is brought into contact with at least one contact member 5 selected from elastic materials such as cloth, resin and rubber. By wiping off the sizing agent liquid attached to the guide roller by the contact member 5, the degree of adhesion of the guide roller surface can be adjusted to 0.2 N / cm ² or less.

Here, the method for bringing the contact body into contact with the guide roller is not particularly limited, and for example, a method for uniformly pressing the contact body against the guide roller may be mentioned. As a contact body to be pressed, a sizing agent liquid attached to the guide roller, such as cloth, flannel, elastic material such as resin or rubber, metal, etc. can be removed, and the guide roller surface adhesiveness is 0.2 N / cm ² or less. It will not matter if you can. In particular, it is most suitable for the effect of sizing solution removal because of the static electricity generation, durability and water absorbency, plain weave cotton cloth with hair and foot, cotton foot and hair cloth with flannel, etc. It is.

  The pressing pressure of the contact body is not particularly limited as long as the sizing agent liquid attached to the guide roller can be removed, and the installation state of the contact body may be either fixed or rotating. However, if the pressing pressure is weak, the removal of the signing solution is insufficient and the effect is weak. However, if the pressing pressure is too high, the guide roller does not rotate and many fluffs of the carbon fiber bundle run by rubbing It is generated and wound around the guide roller, and the process passability is reduced. From this, it is preferable that the cloth-like contact body can be wound around a guide roller and can be rotated. Furthermore, although the position at which the contact body is pressed is not particularly limited, pressing the surface against which the traveling carbon fiber bundle is not in contact prevents fuzz or breakage due to contact between the traveling member and the traveling carbon fiber bundle. Preferred in terms of

  Furthermore, in the case of pressing an elastic material or metal, it is preferable from the viewpoint of the sizing agent liquid removal efficiency that the guide roller be shaped as sharp as a scraper to the extent that the guide roller is not scratched. When the scraper is used, the sizing agent liquid transferred onto the surface of the guide roller as the guide roller rotates is blocked by the sharp tip of the scraper in contact with the guide roller. Further, in order to efficiently hold the sizing agent solution on the entire surface of the guide roller with the scraper, it is preferable that the sharp tip of the scraper be placed in line contact parallel to the axial direction of the guide roller. As the sharp portion of the scraper, a hard scraper blade made of metal or plastic is preferable, and according to this, it is possible to uniformly form a sticky deposit such as a solid deposit or a resin reservoir generated on the guide roller when the sizing agent liquid is dried. It can be removed. In addition, in order to remove the sizing agent solution across the entire width direction of the guide roller with the scraper, a guide means such as a guide rail for the scraper blade is provided in a direction parallel to the axis of the guide roller, and the scraper is installed in the axial direction of the guide roller You may By so doing, solid deposits and sticky deposits on the guide roller can be efficiently removed.

FIG. 2 is a schematic configuration view showing another example of the sizing application process in the present invention. In the embodiment shown in FIG. 2, the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 by passing through the immersion roller 2, and it comes out of the liquid surface by the guide roller 3 and is dried in the next step of the sizing application step. Led. Also in this aspect, the sizing agent liquid adheres to the guide roller 3 by passing the carbon fiber bundle 1 to which the sizing agent liquid is applied. Therefore, in order to prevent the sticking of the sizing agent adhering to the guide roller 3, the sizing agent liquid is applied to the guide roller 3 separately from the sizing agent liquid from the sizing agent liquid tank 4 using the sizing agent liquid spraying means 6 or the like. . The method for applying the sizing agent liquid is not particularly limited to the sizing agent liquid spraying means 6, for example, a method for dropping or jetting the sizing agent liquid over the entire surface of the guide roller, a method for immersing the guide roller in the sizing agent liquid, etc. . In such an embodiment, the sizing agent liquid may be applied to such an extent that the guide roller is not dried, and the adhesion degree of the guide roller surface may be 0.2 N / cm ² or less. There is no particular limitation as long as resin accumulation does not occur due to retention and drying.

For example, as shown in FIG. 2, the sizing agent liquid spraying means 6 is provided on the upper part of the guide roller 3, and the sizing agent liquid is sprayed from the sizing agent liquid spraying means 6 to dry the sizing agent liquid in the guide roller 3. It can be suppressed sufficiently. The upper limit of the sizing spray amount sprayed from the sizing agent spray means 6 is not particularly limited as long as the guide roller 3 is wet, but a preferable range is 50 to 130 mg / cm ² / hr, and a more preferable range is It is 80 to 100 mg / cm ² / hr. When the spray amount is less than 50 mg / cm ² / hr, the sizing agent solution may evaporate on the guide roller 3 to form a resin reservoir, which may cause fuzzing or winding. When the spray amount exceeds 130 mg / cm ² / hr, the sizing amount is excessively used, which is disadvantageous in cost.

  Further, as shown in FIG. 3, the drying of the sizing agent liquid in the guide roller 3 is sufficiently suppressed by immersing the guide roller 3 in the sizing agent liquid tank 8 different from the sizing agent liquid tank used in the sizing application step. it can.

  Although the sizing agent liquid separately applied to the guide roller as in the embodiment shown in FIG. 2 and FIG. 3 is not particularly limited, it is preferable that the composition and amount of the sizing agent applied to the obtained carbon fiber bundle do not change Preferably, the same one as the sizing agent liquid in which the carbon fiber bundle is immersed is good.

  The combination of the method of bringing the contact body into contact with the guide roller and the method of applying the sizing agent liquid separately from the sizing agent liquid tank 4 makes the effect more effective. For example, as shown in FIG. 4, after the sizing solution is sprayed onto the guide roller 3 from the sizing solution spraying means 6, by pressing the contact body, the sizing agent can be reliably obtained from the method of only pressing the contact body. The excess sizing agent solution can be removed while preventing the solution from sticking, and the degree of surface adhesion of the guide roller can be adjusted within a predetermined range.

  Furthermore, in the present invention, the carbon fiber bundle 1 is immersed in the sizing agent liquid tank 4 by passing through the immersion roller 2, and it comes out of the liquid surface by the guide roller 3 and is guided to the drying step of the next step of the sizing application step. It is preferable to use a water-repellent guide roller as the guide roller 3 so as not to cause the guide roller 3 to generate a resin reservoir due to the sizing agent liquid. As a specific example of a guide roller which has water repellency, resin made from fluorine and stainless steel (SUS) are mentioned. In particular, when the carbon fiber bundle to which the sizing agent solution is applied travels on the guide roller, the guide roller surface is always in a wet state, and therefore stainless steel (SUS) which is resistant to rusting is more preferable. As types of stainless steel, SUS304, SUS304L, SUS316, SUS316L and the like can be mentioned.

  Further, in the manufacturing method of the present invention, after immersing the carbon fiber bundle in the sizing agent solution, the position from the liquid surface to the guide roller to be first contacted and the position from the guide roller to the drying step Thus, a sizing agent liquid film is likely to be formed between adjacent yarns. The sizing agent liquid film is an excess sizing agent liquid carried out by the carbon fiber bundle immersed in the sizing agent liquid tank, or the sizing agent liquid applied to the guide roller separately from the sizing agent liquid of the sizing agent liquid tank as described above. Can be formed by When the sizing agent liquid film is formed between adjacent yarns, adjacent yarns come into contact with each other due to the surface tension of the sizing agent liquid film to generate fluff, or sizing agent adhesion spots or drying of the obtained carbon fiber bundle Mottle, color spots increase. Therefore, it is preferable to remove the sizing agent liquid film at each position. The method for removing the sizing agent liquid film is not particularly limited, but may be injection of pressurized gas, application of vibration, application of ultrasonic waves, physical contact by installing a guide, and the like. Among them, the non-contact method is preferable because the generation of fluff of the carbon fiber bundle can be easily prevented, and the injection of the pressurized gas is more preferable from the viewpoint of reducing the equipment cost.

  In the manufacturing method of the present invention, the tension of the carbon fiber bundle in the sizing agent application step is preferably set to 3.5 to 8.5 cN / tex. When the tension is 3.5 cN / tex or more, it is possible to prevent the decrease in the convergence of the carbon fiber bundle. On the other hand, in the case of 8.5 cN / tex or less, it is possible to easily prevent the occurrence of fuzz and thread breakage due to tension application. From the above viewpoints, the tension of the carbon fiber bundle in the sizing agent application step is preferably 3.5 to 8.5 cN / tex, more preferably 4.0 to 8.0 cN / tex, and still more preferably It is 4.5-7.5 cN / tex. Further, the tension of the carbon fiber bundle in the sizing agent application process may be controlled solely in the sizing agent application process or may be controlled by the same mechanism as the tension in the drying process. Although the control method of tension is not particularly limited, a method by adjusting the ratio of the driving speed before and after the sizing agent applying step may be mentioned. The process tension can be grasped by measuring the traveling yarn immediately before applying the sizing agent liquid using a tensiometer or the like, and can be adjusted by the roller rotation torque etc. before and after applying the sizing agent liquid.

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

  The present invention will be more specifically described by examples and comparative examples. Moreover, each evaluation item in an Example and a comparative example was implemented by the following evaluation methods.

[Guide roller surface adhesion degree]
The guide roller surface adhesion was calculated by the following equation.
Roller surface adhesion (N / cm ² ) = moving force of carbon fiber bundle / guide roller surface contact area of carbon fiber bundle.

  The moving force of the carbon fiber bundle was measured as follows 5 minutes after stopping the carbon fiber bundle production facility during long-term stable production. That is, as shown in FIG. 5, after fixing the guide roller 3 made of stainless steel to which the sizing agent liquid is attached so as not to rotate, the completely dried carbon fiber bundle 1 just before applying the sizing agent liquid It hung from the top point of 3 and was applied with a contact angle of 180 °. Thereafter, a ring was formed at one end of the carbon fiber bundle 1. The load measuring instrument 7 used digital push pull gauge (RX series, part number RX-10) manufactured by Aiko Engineering Co., Ltd. Attach a hook that is a gauge attachment (product number 011B) to the tip of the digital push-pull gauge, and with the hook hooked on the ring of the carbon fiber bundle 1, slowly pull the carbon fiber bundle 1 in the circumferential direction of the guide roller 3. I pulled it. The maximum force immediately before the carbon fiber bundle 1 moved on the surface of the guide roller 3, that is, the moving force of the carbon fiber bundle was measured using a push-pull gauge.

  Moreover, the guide roller surface contact area of the carbon fiber bundle was calculated by the product of the guide roller circumferential length in contact with the carbon fiber bundle and the yarn width of the carbon fiber bundle.

[Grade]
As the quality of the sizing agent-added carbon fiber bundle, the end face fluff of the bobbin of the carbon fiber bundle after packaging was observed, and the judgment was made according to the following criteria.
== 5 fluffs / 100 mm ^{2 or} less ○ = 5 fluffs 5/100 mm ² or more 10 10/100 mm ² × = 10 fluffs 10 lines / 100 mm ² or more.

Example 1
A sizing agent was applied to a plurality of carbon fiber bundles that run in parallel in the configuration shown in FIG. 1, and a sizing agent applied carbon fiber bundle was obtained through a drying process.

  Specifically, a sizing agent having a concentration of 3% by mass and a carbon fiber bundle of 3000 filaments having a polyacrylonitrile-based fiber as a precursor fiber bundle and a bisphenol A epoxy resin as an aromatic epoxy compound as a main component It was made to immerse in the sizing agent liquid tank filled with the liquid, and it continued to be provided to the drying process, and the sizing agent added carbon fiber bundle was obtained. After the carbon fiber bundle comes out of the liquid surface of the sizing agent, a guide roller made of stainless steel (SUS) is used as the guide roller 3 which contacts first, and the lower end of the guide roller 3 I pressed cotton cloth with a foot.

The surface tackiness of the guide roller 3 was 0.05 N / cm ² , and the end face fuzz grade was very good. The results are shown in Table 1.

Example 2
A sizing agent-added carbon fiber bundle was obtained in the same manner as in Example 1 except that a plastic scraper was used instead of the cotton flannel cloth having hair and feet as the contact body 5. The surface tackiness of the guide roller 3 was 0.07 N / cm ² and the end face fuzz grade was very good. The results are shown in Table 1.

  [Example 3]
  A sizing agent added carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent applying step was changed to the step shown in FIG. That is, all were the same as Example 1 except that the sizing agent liquid was jetted from the upper portion of the guide roller 3 which contacts first after the carbon fiber bundle comes out of the sizing agent liquid surface and the contacting body is removed. The injection amount of sizing agent liquid at this time is 100 mg / cm²It was set to / hr. The surface tackiness of the guide roller 3 is 0.04 N / cm ²The end face fluff quality was very 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 injection amount of the sizing agent solution was changed to 80 mg / cm ² / hr. The surface tackiness of the guide roller 3 was 0.13 N / cm ² and the end face fuzz grade was good. The results are shown in Table 1.

[Example 5]
A sizing agent applied carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent applying process was changed to the process shown in FIG. That is, except that the guide roller 3 which was first in contact with the carbon fiber bundle after coming out of the sizing agent liquid surface in Example 1 was immersed in another independent sizing agent liquid tank 8 and the contact body was removed. All were the same as in Example 1. The surface tackiness of the guide roller 3 was 0.08 N / cm ² , and the end face fuzz grade was good. The results are shown in Table 1.

[Example 6]
A sizing agent applied carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent applying process was changed to the process shown in FIG. That is, the same procedure as in Example 1 was repeated except that the sizing agent solution was sprayed onto the carbon fiber bundle delivered from the guide roller 3 at a spraying amount of 80 mg / cm ² / hr. The surface tackiness of the guide roller 3 was 0.02 N / cm ² , and the end face fuzz grade was very good. The results are shown in Table 1.

[Example 7]
A sizing agent added carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent solution tank having a concentration of 2% by mass containing polyurethane as a main component was filled in the sizing agent solution tank. The surface tackiness of the guide roller 3 was 0.06 N / cm ² and the end face fuzz grade was very good. The results are shown in Table 1.

Comparative Example 1
A sizing agent added carbon fiber bundle was obtained in the same manner as in Example 1 except that the sizing agent applying step was changed to the step shown in FIG. That is, the procedure was the same as in Example 1 except that the cotton flannel cloth as the contact body was not pressed. As a result, the sizing agent is dried on the guide roller and resin accumulation occurs, and the surface tackiness of the guide roller 3 is increased to 0.25 N / cm ² , the traveling carbon fiber bundle is fluffed, and the end face fluff quality Was significantly worse. The results are shown in Table 1.

1: Carbon fiber bundle 2: Immersion roller 3: Guide roller 4: Sizing agent tank 5: Contact body 6: Sizing agent spraying means 7: Load measuring device 8: Sizing agent liquid different from sizing agent liquid tank 4 Tank

Claims (3)

After the sizing agent application step of immersing a plurality of carbon fiber bundles running in parallel in the sizing agent liquid tank, the carbon fiber bundle is subjected to a drying step to obtain a sizing agent applied carbon fiber bundle through a drying step. Sizing agent-imparted carbon fiber bundle in which the guide roller surface adhesion degree in the first guide roller after immersion in the sizing agent liquid tank and the carbon fiber bundle comes out of the liquid surface of the sizing agent liquid tank is 0.2 N / cm ² or less Manufacturing method. The manufacturing method of the sizing agent provision carbon fiber bundle of Claim 1 which makes guide roller surface adhesion degree 0.2 N / cm < ² > or less by making a contact body contact a guide roller. The manufacturing method of the sizing agent provision carbon fiber bundle of Claim 1 which makes guide roller surface adhesiveness degree or less 0.2 N / cm < ² > or less by further providing a sizing agent liquid after a sizing agent provision process.

Images