WO2010053170A1

WO2010053170A1 - Fiber bundle with pieced part, process for producing same, and process for producing carbon fiber

Info

Publication number: WO2010053170A1
Application number: PCT/JP2009/069032
Authority: WO
Inventors: 三島　邦裕; 廣瀬　孝光; 公康加藤; 尾崎　充利; 大樹渡辺
Original assignee: 東レ株式会社
Priority date: 2008-11-10
Filing date: 2009-11-09
Publication date: 2010-05-14
Also published as: MX2011004878A; US20110217228A1; EP2348143A4; CN102209806B; EP2348143A1; CN102209806A; KR20110084420A; ES2453622T3; KR101564801B1; EP2348143B1

Abstract

A fiber bundle which has a pieced part formed by jetting a pressurized fluid against a fiber-bundle overlap formed either by directly superposing the ending part of a fiber bundle composed of many fibers on the beginning part of another fiber bundle composed of many fibers or by superposing the end part and the beginning part on a jointing fiber bundle composed of many fibers, whereby the many fibers of the fiber bundles are interlaced with one another to thereby piece up the fiber bundles. The pieced part comprises an opened-fiber part in which the fibers have been opened and interlaced-fiber parts respectively located on both sides thereof, each interlaced-fiber part being composed of a plurality of constituent interlaced parts located apart in the width direction for the fiber bundle. The fiber bundle having the pieced part, when fed to a process for producing a carbon fiber, is inhibited from suffering thermal damage to the pieced part, because the pieced part comprises the opened-fiber part and the interlaced-fiber parts.

Description

Fiber bundle having yarn splicing joint, method for producing the same, and method for producing carbon fiber

The present invention relates to a fiber bundle having a yarn splicing joint, a manufacturing method thereof, and a carbon fiber manufacturing method. When producing carbon fibers from a precursor fiber bundle for producing carbon fibers, it may be necessary to supply the precursor fiber bundle continuously to the carbon fiber production process for a long time. In that case, it is necessary to prepare one continuous precursor fiber bundle by joining one end portion and the other start end portion of two precursor fiber bundles for producing carbon fibers. In creating this single continuous precursor fiber bundle, the fiber bundle having the yarn splicing joint of the present invention is effectively used.

Generally, a precursor fiber bundle for carbon fiber production is used in the carbon fiber production process. This precursor fiber bundle is usually prepared in the precursor fiber bundle supply section in a form wound up on a bobbin or the like, or a form folded and laminated in a box. The precursor fiber bundle drawn out from the precursor fiber bundle supply unit is usually supplied to a firing process including a flameproofing process and a carbonization process.

Therefore, in order to continuously fire these precursor fiber bundles for a long time and continue to produce carbon fibers for a long time, the starting end portion of the precursor fiber bundle drawn from the precursor fiber bundle supply unit Need to be joined to the end portion of the precursor fiber bundle that is passing through the firing step by some means. By joining the end portions in the longitudinal direction of these precursor fiber bundles, the precursor fiber bundle can be continuously supplied to the carbon fiber production process, and as a result, the operability of the process is improved. .

A method is known in which end portions in the longitudinal direction of polyacrylonitrile-based precursor fiber bundles, which are precursor fiber bundles for producing two carbon fibers, are entangled with each other by a pressurized fluid (see Patent Document 1). .

However, it is possible to join the end portions of the precursor fiber bundle by this method, but since the density of the fibers in the formed yarn splicing joint portion is increased, in the flameproofing process, the precursor fiber bundle itself There was a problem that the oxidation reaction was likely to run away due to heat generation. Therefore, there has been an accident that the yarn splicing joint is burned out or burnt out. In order to avoid yarn breakage at the yarn splicing joint due to heat storage, there is a method for reducing the temperature of the flameproofing step. However, if the temperature decrease in the flameproofing process is large, the time required for the flameproofing process becomes long, and the productivity of the desired carbon fiber is significantly reduced.

When the number of single fibers (number of filaments) of the precursor fiber bundle is large, the pressurized fluid ejected from the pressurized fluid injection nozzle does not hit the entire precursor fiber bundle, and the precursor fiber bundle is entangled at the single fiber level. Instead, it gets tangled in several small bundles. When such small bundles are entangled unevenly at the joint, a portion having a high fiber density is locally formed, and heat is easily stored. Moreover, the entanglement of the fibers at the joint becomes insufficient, and the binding strength between the precursor fiber bundles becomes weak. As a result, there is a problem that the fiber bundle is broken or the yarn splicing joint is unsatisfactory because it cannot withstand the process tension.

As a countermeasure against these, for example, a method is known in which two polyacrylonitrile-based precursor fiber bundles are joined using a connection medium (connection fiber bundle) made of non-heat-generating flame-resistant yarn (patent document). 2). However, in this method, although there is an effect of reducing the amount of stored heat, heat removal at the joint is not sufficient, and therefore, yarn breakage or the like still tends to occur at the joint where the fiber density increases.

Therefore, when the yarn splicing joint passes through the flameproofing process, the furnace temperature had to be lowered. In addition, the flameproofing yarn forming the connecting fiber bundle and the fiber forming the polyacrylonitrile-based precursor fiber bundle are different in the degree of fiber bending in each fiber bundle, so the polyacrylonitrile-based precursor fiber bundle is The formed fiber and the flameproof yarn forming the connecting fiber bundle are not sufficiently mixed and are not entangled uniformly. For this reason, the fiber bundles of both of them are easily removed, and there is a problem that the flameproofing furnace has to be stopped for disaster prevention.

In addition, there is also known a method in which the fiber bundle is divided into a plurality of small bundles at the end portion of each fiber bundle, and the small bundles are knitted together and joined instead of the tangled joining formed by pressurized air. (See Patent Document 3). In this case, since the connection state is a knot, the knot is tightened, the fiber density at the joint is increased, and yarn breakage due to heat storage occurs. In addition, since the binding strength between the small bundles at the joint varies, there is a problem that stress concentrates on the small bundle with the weak binding strength and breaks in order from the small bundle with the low binding strength.

Further, the end portions of the precursor fiber bundles are pre-flame-resistant and formed with a flame-resistant fiber bundle having a density of 1.30 g / cm ³ or more, and the precursor fiber bundles having the end portions are connected to each other at the end portions. A polyacrylonitrile fiber bundle for producing carbon fibers in which fibers are entangled and integrated to form a joint has been proposed (see Patent Document 4). In this case, although there is a tendency to improve with respect to yarn breakage due to heat storage at the joint, a dedicated facility is required to make the end portion of the precursor fiber bundle into a flame-resistant fiber. I can't say.

Japanese Patent Laid-Open No. 06-206667 Japanese Patent Laid-Open No. 10-226918 JP 2007-046177 A JP 2000-144534 A

An object of the present invention is to provide a fiber bundle having a yarn splicing joint that can solve the above-described problems of the prior art, and a method for manufacturing the same. In addition, the purpose of the present invention is that the yarn splicing joint of the present invention has less heat storage in the splicing joint, hardly burns out due to heat storage in the splicing joint in the firing process, and has good processability of the fiber bundle. It is providing the manufacturing method of carbon fiber using the fiber bundle which has a part.

The fiber bundle having the yarn splicing joint of the present invention is as follows.

One end portion of the first fiber bundle composed of a large number of fibers and one end portion of the second fiber bundle composed of a large number of fibers overlap each other, or Two fibers formed such that one end of the first fiber bundle made of fibers and one end of the second fiber bundle made of many fibers overlap each other on a connecting fiber bundle made of many fibers A plurality of fiber entangled portions having a bundle overlapping portion, wherein the fiber bundle overlapping portions are in an intertwined state with the fibers positioned at intervals in the longitudinal direction of the fiber bundles; Each of the fibers located between the plurality of fiber entangled portions has a fiber spread portion in a state where each fiber is opened, and each of the fiber entangled portions is the fiber bundle overlapping portion. The multiple fibers of one fiber bundle in And the plurality of fibers of the other fiber bundle are entangled with each other, consisting of a plurality of partially entangled portions that are located at intervals in the width direction of each fiber bundle, and the plurality of fiber entangled portions, The fiber bundle which has the thread splicing junction part in which each said fiber bundle is joined in the said fiber bundle superimposition part.

In the fiber bundle having the yarn splicing joint of the present invention, it is preferable that each of the first fiber bundle and the second fiber bundle is a precursor fiber bundle for producing carbon fibers.

In the fiber bundle having the yarn splicing joint of the present invention, it is preferable that the thermal conductivity of the connection fiber bundle is 3 to 700 W / m · K.

In the fiber bundle having the yarn splicing joint of the present invention, it is preferable that the connection fiber bundle is a carbon fiber bundle, the drape value is 2 to 15 cm, and the flatness is 20 or more. .

In the fiber bundle having the yarn splicing joint of the present invention, the fineness of the connecting fiber bundle is preferably 0.2 to 3.0 times the fineness of the first fiber bundle and the second fiber bundle. .

In the fiber bundle having the yarn splicing joint portion of the present invention, the tensile strength at normal temperature of the yarn splicing joint portion is preferably 20 g / tex or more.

In the fiber bundle having the yarn splicing joint of the present invention, the length of each fiber entangled portion in the longitudinal direction of the fiber bundle is 8 to 30 mm, and the length of the fiber spread portion in the longitudinal direction of the fiber bundle Is preferably 30 to 100 mm.

The manufacturing method of the fiber bundle having the yarn splicing joint of the present invention is as follows.

One end portion of the first fiber bundle composed of a large number of fibers and one end portion of the second fiber bundle composed of a large number of fibers overlap each other, or Two fibers formed such that one end of the first fiber bundle made of fibers and one end of the second fiber bundle made of many fibers overlap each other on a connecting fiber bundle made of many fibers In the fiber bundle overlapping portion, each fiber is entangled by injecting a pressurized fluid from a fiber entanglement device to the fiber bundle overlapping portion of the fiber bundle having the bundle overlapping portion. In the manufacturing method of the fiber bundle which has the thread splicing junction part which joins bundles, the said fiber entanglement apparatus is the some linearly arranged on the 1st straight line which faces the width direction of the said fiber bundle. Fluid injection hole A first fluid ejection hole array and a second straight line parallel to the first straight line that is located at a distance in the longitudinal direction of the fiber bundle with respect to the first straight line. And a plurality of fluid ejection holes of the first fluid ejection hole array, and a plurality of fluid ejections of the second fluid ejection hole array. A plurality of fiber entangled portions in which the fibers positioned at intervals in the longitudinal direction of the fiber bundles are intertwined with each other in the fiber bundle overlapping portion by ejecting pressurized fluid from the holes And forming a fiber opening portion in a state where each of the fibers located between the plurality of fiber entangled portions is opened, and each of the fiber entangled portions is formed as the fiber bundle overlapping portion. The multiple fibers and the other fiber bundle of one fiber bundle in The plurality of fibers are entangled with each other, and formed so as to consist of a plurality of partial entanglements positioned at intervals in the width direction of the respective fiber bundles. The manufacturing method of the fiber bundle which has the thread splicing junction part joined.

In the method for producing a fiber bundle having a yarn splicing joint according to the present invention, each of the first fiber bundle and the second fiber bundle is preferably a precursor fiber bundle for producing carbon fibers.

In the method for producing a fiber bundle having a yarn splicing joint according to the present invention, the connecting fiber bundle preferably has a thermal conductivity of 3 to 700 W / m · K.

In the method for producing a fiber bundle having a yarn splicing joint according to the present invention, the connecting fiber bundle is a carbon fiber bundle, the drape value is 2 to 15 cm, and the flatness is 20 or more. It is preferable.

In the method for manufacturing a fiber bundle having a yarn splicing joint according to the present invention, the fineness of the connecting fiber bundle is 0.2 to 3.0 times the fineness of the first fiber bundle and the second fiber bundle. It is preferable.

In the method for producing a fiber bundle having a yarn splicing joint according to the present invention, it is preferable that the tensile strength at normal temperature of the yarn splicing joint is 20 g / tex or more.

In the method for manufacturing a fiber bundle having a yarn splicing joint according to the present invention, an interval between the first straight line and the second straight line is 20 to 100 mm, and the first fluid ejection hole array and the second straight line are arranged. The arrangement pitch of the fluid ejection holes in the fluid ejection hole row is preferably 1.7 to 4.5 mm.

The carbon fiber production method of the present invention is as follows.

A carbon fiber manufacturing method for manufacturing a carbon fiber by continuously passing a fiber bundle having a yarn splicing joint of the present invention through a flameproofing furnace and then a carbonizing furnace.

According to the fiber bundle having the yarn splicing joint of the present invention, when the fiber bundle is continuously fired in the firing step, in the firing step, the fiber bundle is broken or the fiber forming the fiber bundle is There is an effect that heat storage at the yarn joining portion is suppressed and that heat removal at the yarn joining portion is good without coming off from the fiber bundle.

Therefore, the temperature in the furnace in the firing process that is usually employed when the fiber bundle that does not have the yarn splicing joint, or the fiber bundle having the yarn splicing joint but other than that portion passes through the firing process. Without significantly lowering the fiber bundle having the yarn splicing joint of the present invention can be continuously passed through the firing process, so that the fired fiber, Carbon fiber can be produced continuously for a long time. The result is a significant increase in the productivity of fired fibers, such as carbon fibers.

FIG. 1 is a schematic longitudinal sectional view of an example of a fiber bundle having a yarn splicing joint according to the present invention. FIG. 2 is a schematic longitudinal sectional view of another example of a fiber bundle having a yarn splicing joint according to the present invention. FIG. 3 is a schematic longitudinal sectional view of still another example of a fiber bundle having a yarn splicing joint according to the present invention. FIG. 4 is a schematic plan view of one yarn joining portion as an example of a fiber bundle having the yarn joining joint portion of the present invention. FIG. 5 is a schematic side view of an example of a yarn splicing device used when carrying out the method of manufacturing a fiber bundle having a yarn splicing joint according to the present invention. FIG. 6 is a schematic cross-sectional view of an example of a fiber entanglement device for imparting entanglement to fibers used for carrying out the method of manufacturing a fiber bundle having a yarn splicing joint according to the present invention. 7 is an S1-S1 cross-sectional arrow view of the fiber entanglement apparatus of FIG. FIG. 8 is a schematic side view for explaining a state in which one yarn splicing joint portion of an example of a fiber bundle having the yarn splicing joint portion of the present invention is formed by the fiber entanglement device of FIG. FIG. 9 is a schematic side view of a measurement sample creating apparatus for preparing a measurement sample used when measuring a drape value of a connecting fiber bundle used in a fiber bundle having a yarn splicing joint according to the present invention. It is. FIG. 10 is a schematic side view of a drape value measuring apparatus that measures a drape value using a measurement piece cut out from the measurement sample obtained in FIG. 9. FIG. 11 is a schematic side view for explaining a measurement method for measuring a drape value using a measurement piece attached to the drape value measurement apparatus of FIG.

First, an embodiment of the carbon fiber production method of the present invention will be described. As precursor fiber bundles for producing carbon fibers, polyacrylonitrile fiber bundles, pitch fiber bundles, cellulose fiber bundles, and the like are used. Among them, polyacrylonitrile fiber bundles are widely used because high strength is easily developed.

The process passing speed of the fiber bundle in the process of producing the polyacrylonitrile-based precursor fiber bundle, which is the carbon fiber production raw yarn, and the fiber bundle in the firing process of producing the carbon fiber by firing the obtained precursor fiber bundle The process passing speed is greatly different. Therefore, since the precursor fiber bundle manufactured in the manufacturing process of the precursor fiber bundle cannot be continuously supplied to the firing process, the precursor fiber bundle is temporarily stored in an appropriate storage form. Appropriate storage forms include a form wound on a bobbin and a form laminated in a box. The precursor fiber bundle once stored is then pulled out from the storage location and supplied to the firing step.

In the following description, the precursor fiber bundle that has already been pulled out from the storage location (bobbin) and supplied to the firing step is drawn from the first fiber bundle, and then from another storage location (another bobbin) to the firing step. The precursor fiber bundle to be supplied to the second fiber bundle is defined as the second fiber bundle.

The first fiber bundle is drawn out of the storage place and then subjected to a flameproofing treatment in a flameproofing furnace in the firing step. In this flameproofing treatment, the first fiber bundle is usually heat-treated at a temperature of 180 to 400 ° C. in an oxidizing atmosphere to form a flameproof yarn. In the firing step, the flameproof yarn is carbonized in a carbonization furnace located after the flameproofing furnace to form carbon fibers. The carbon fiber drawn out from the carbonization furnace is subjected to a surface treatment such as application of a sizing agent in the surface treatment step, if necessary, and then wound up in the winding step to become a carbon fiber product.

When the first fiber bundle drawn from the storage location reaches its end portion, the end portion of the first fiber bundle and the start end portion of the second fiber bundle drawn from another storage location are used as a yarn. Connected and joined together. That is, the end portions of the precursor fiber bundle are joined together, and the joined second fiber bundle is introduced into the firing step as the first fiber bundle moves, and carbon fibers are continuously produced. .

The fiber bundle having the yarn splicing joint portion of the present invention was developed for the purpose of preventing yarn breakage due to heat accumulation in the yarn splicing joint portion during passage of the flameproofing process and breakage of the fiber bundle during passage of the process. Is. There are the following two modes as the form of the yarn joining portion.

A fiber bundle having a yarn splicing joint in which the first mode in the form of a yarn splicing joint is used is shown in FIG. In FIG. 1, a fiber bundle 1 having a yarn splicing joint has an end portion (terminal portion) 5 of a first fiber bundle FB1 and an end portion (start end portion) 6 of a second fiber bundle FB2 in the longitudinal direction. The yarn splicing joint A is formed in a state of being overlapped with each other. In the fiber bundle overlapping portion where the first fiber bundle FB1 and the second fiber bundle FB2 overlap, a plurality of yarn splicing joints A are provided as needed at intervals in the longitudinal direction. I can do it.

A fiber bundle having a yarn splicing joint in which the second mode in the form of a yarn splicing joint is used is shown in FIG. In FIG. 2, the fiber bundle 2 having the yarn splicing joint is composed of a first fiber bundle FB1, a second fiber bundle FB2, and a connection fiber bundle JFB. The fiber bundle 2 having a yarn splicing joint is formed in a state in which the end portion (terminal portion) 5 of the first fiber bundle FB1 and one end portion 4a of the connection fiber bundle JFB are overlapped with each other in the longitudinal direction. One of the yarn joining joints A, the end (starting end) 6 of the second fiber bundle FB2, and the other end 4b of the connecting fiber bundle JFB are overlapped with each other in the longitudinal direction. It has the other yarn splicing joint A.

FIG. 3 shows a deformation mode of the fiber bundle 2 having the yarn splicing joint portion in which the second mode of the yarn splicing joint portion shown in FIG. 2 is used. In FIG. 3, the fiber bundle 3 having the yarn splicing joint is composed of the first fiber bundle FB1, the second fiber bundle FB2, and the connection fiber bundle JFB, similarly to the fiber bundle 2 of FIG. The fiber bundle 3 having the yarn splicing joint in FIG. 3 is different from the fiber bundle 2 in FIG. 2 in that the first fiber bundle FB1 and the connecting fiber bundle JFB are overlapped with each other in the longitudinal direction. Three fiber splicing joints A, and a bundle of fiber bundles where the second fiber bundle FB2 and the connecting fiber bundle JFB overlap each other with a gap in the longitudinal direction. This is a point having a yarn joining portion A. The number of yarn splicing joints A in the fiber bundle overlapping portion is appropriately selected as necessary.

In addition, the superposition form itself of the first fiber bundle and the second fiber bundle described above, and the first fiber bundle and the connection fiber bundle, and the second fiber bundle and the connection fiber bundle The superposition forms themselves are already known.

Next, the structure of the yarn splicing joint in the fiber bundle having the yarn splicing joint of the present invention will be described. The feature of the fiber bundle having the yarn splicing joint of the present invention is the structure of this yarn splicing joint.

FIG. 4 is a schematic plan view showing an example of the yarn splicing joint A in the fiber bundle having the yarn splicing joint of the present invention. In FIG. 4, the yarn splicing joint A has two fibers in a state where the fibers forming the fiber bundles positioned at intervals in the longitudinal direction of the fiber bundles that are superimposed are intertwined with each other. It has the fiber entangled part (entangled part) C and the fiber opening part B in the state which each fiber located between these two fiber entangled parts C is mutually opened. Further, each fiber entangled portion C is formed by intertwining a plurality of fibers of one fiber bundle and a plurality of fibers of the other fiber bundle in each fiber bundle overlapping portion, and is spaced in the width direction of each fiber bundle. It consists of a plurality of partially entangled portions D that are positioned. The respective fiber bundles that are superposed are joined together by two fiber entangled portions C in the fiber bundle superposed portion to form a continuous fiber bundle having a yarn joining portion A.

As shown in FIG. 4, the yarn splicing joint A in which the ends of the two fiber bundles are overlapped has a fiber opening part B in which a large number of fibers in the two fiber bundles are opened. When the fiber bundle having this yarn splicing joint A is supplied to the flameproofing process and subjected to heat treatment, the fiber opening part B functions as a heat radiating part that releases the heat that tends to accumulate in the fiber bundle to the outside, Heat storage at the yarn splicing joint A in the flameproofing process is prevented or alleviated.

The fiber opening part (heat dissipating part) B is a single fiber in which a pressurized fluid (pressurized air) ejected in a fiber entanglement device, which will be described later, directly hits the fiber bundle, and a large number of fibers forming the fiber bundle This is the area where fibers are spread to the level and mixed without interlacing. In the fiber opening part B, it is preferable that the single fibers are not bonded to each other and are in contact with the outside air. In FIG. 4, the state of heat dissipation in the fiber opening part B is schematically indicated by an arrow HR.

In FIG. 4, if the length X in the longitudinal direction of the fiber bundle of the fiber opening part B is too short, the heat dissipation effect is reduced, and if it is too long, the entire yarn splicing device is enlarged. The length X of B is preferably 30 to 100 mm, and more preferably 35 to 50 mm. In addition, the length (width) of the fiber bundle of the fiber opening part B in the width direction is preferably 1.5 to 2 times the length (width) of the fiber bundle before fiber opening. .

If the length in the width direction of the fiber bundle of the fiber opening part B is less than 1.5 times the length in the width direction of the fiber bundle before opening, the fibers are not sufficiently opened, and sufficient The heat dissipation effect may not be obtained. Moreover, when the length in the width direction of the fiber bundle of the fiber opening part B exceeds twice the length in the width direction of the fiber bundle before opening, the fiber opening part B becomes too large, While passing through the process, the fibers of the fiber bundle running next to each other may be brought into contact with each other to cause fiber mixing between them.

Thus, the presence of the fiber opening part B allows the heat stored in the fiber entangled part C located on both sides thereof to be released to the outside. As a result, the amount of heat accumulated in the yarn splicing joint A can be reduced, and yarn breakage due to heat accumulation can be greatly reduced.

The fiber entangled portion (entangled portion) C refers to a region where a plurality of, preferably 4 to 10 partial entangled portions D exist in the width direction of the fiber bundle. The partially entangled portion D refers to a portion where a large number of fibers in two superimposed fiber bundles are entangled with each other at the single fiber level and wound around each other. In FIG. 4, each partial entangled portion D is shown in a state where the fibers are entangled in eight stitches existing from both ends of the fiber spread portion B in the longitudinal direction of the fiber bundle.

In FIG. 4, if the length Y in the longitudinal direction of the fiber bundle of the fiber entangled portion C is too short, the binding strength between the fibers becomes small, and if it is too long, the entire yarn splicing device increases in size. The length Y in the longitudinal direction of the fiber bundle of the part C is preferably 8 to 30 mm, and more preferably 10 to 18 mm.

By forming the fiber entangled part C with a plurality of partial entangled parts D arranged at intervals in the width direction of the fiber bundle, while maintaining the bond between the two fiber bundles in the fiber entangled part C, The fiber bundle can be in a finely divided state. When the number of the partial entanglement parts D is four or more, the number of filaments contained in each partial entanglement part D can be made into 1/4 or less of the total filament number of a fiber bundle. For example, when the first fiber bundle having 12,000 filaments and the second fiber bundle having 12,000 filaments are joined, the number of filaments included in each partially entangled portion D is: About 6,000.

That is, since it is possible to prevent the density of fibers in each partially entangled portion D from being increased, heat storage in the yarn joining portion A can be suppressed. When the number of the partial entangled portions D is 11 or more, the number of filaments included in each partial entangled portion D is reduced, the fiber binding strength of one partial entangled portion D is lowered, and it can withstand the process tension. The fiber bundle is not easily broken. Since the entangled state of the fibers in each partially entangled portion D is substantially uniform, the fiber entangled portion provides sufficient joining strength to the yarn joining portion A.

On the other hand, the heat generated in each partially entangled portion D moves to the fiber opening portion B along the fiber. In FIG. 4, this heat transfer state is schematically shown by an arrow H.

FIG. 5 is a schematic side view of an example of a yarn splicing device used when carrying out the method for producing a fiber bundle having a yarn splicing joint according to the present invention. In FIG. 5, the yarn joining device 50 includes four fiber bundle clamp devices 52 disposed in the longitudinal direction of the device at intervals, and three fiber entanglement devices provided between the fiber bundle clamp devices 52. 51 and six fiber bundle relaxation devices 53 provided between the fiber bundle clamp device 52 and the fiber entanglement device 51a. Each fiber entanglement device 51 includes an upper fiber entanglement device 51a and a lower fiber entanglement device 51b that face each other at an interval in the vertical direction.

On the lower surface of the upper fiber entanglement device 51a and on the upper surface of the lower fiber entanglement device 51b, a first fiber bundle FB1 and a second fiber bundle FB2 in which a plurality of fluid ejection holes are conducted to the yarn splicing device 50. Two rows are opened in parallel in the width direction of the fiber bundle and at intervals in the longitudinal direction of the fiber bundle.

Each fiber bundle clamp device 52 has an upper clamp plate and a lower clamp plate that are opened and closed in the vertical direction so as to sandwich the overlapped first fiber bundle FB1 and second fiber bundle FB2.

Each fiber bundle relaxation device 53 is used to relax the first fiber bundle FB1 and the second fiber bundle FB2 that are superposed on each other in a longitudinal direction, and each fiber bundle clamp device 52 clamps the fiber bundle. In a state in which the fiber bundle is not moved, the fiber bundle is pushed down with a roller extending in the width direction of the fiber bundle movable in the vertical direction, for example, thereby relaxing the fiber bundle by a certain length in the longitudinal direction. After the relaxed state of the fiber bundle is formed, each fiber bundle clamp device 52 is operated to clamp the fiber bundle. This relaxed state of the fiber bundle is preferable in order to facilitate the entanglement of a large number of fibers forming the fiber bundle by each fiber entanglement device 51, and also useful for adjusting the degree of fiber entanglement.

A method of connecting the first fiber bundle FB1 and the second fiber bundle FB2 using the yarn splicing device 50 will be described.

First, the end portion of the first fiber bundle FB1 passing through the firing step and the start end portion of the second fiber bundle FB2 that passes through the firing step are overlapped and positioned in the fiber entanglement device 51. Each end portion is preferably overlapped by 350 to 500 mm in the longitudinal direction of the fiber bundle. The fiber bundles FB1 and FB2 are preferably overlapped in a flat shape having a thickness of 0.1 to 1.0 mm. By doing so, when the fiber entanglement device 50 is subjected to the pressurized fluid treatment, the fiber bundle overlapping section opens a large number of fibers in both fiber bundles FB1 and FB2 to a single fiber level. And can be sufficiently mixed and entangled.

Next, a relaxed portion is formed in the overlapped fiber bundle in the vicinity of the fiber entanglement device 51 by the fiber bundle relaxation device 53 provided adjacent to the fiber entanglement device 51. Specifically, for example, using a weight, both fiber bundles FB1 and FB2 are pushed down and loosened with the weight. The degree of relaxation is preferably 5 to 25%. If the degree of relaxation is less than 5%, the degree of entanglement will be weak, so the binding strength of the joint will be reduced, and if the degree of relaxation exceeds 25%, the fiber entangled part will be larger, Thread breakage is likely to occur.

Next, the two fiber bundles are held by the upper clamp plate and the lower clamp plate in the fiber bundle clamp device 52 and fixed so that the overlap of the two fiber bundles FB1 and FB2 is not broken. Next, the weights that relax the fiber bundles FB1 and FB2 are removed, and pressurized fluid is ejected from the upper fiber entanglement device 51a and the lower fiber entanglement device 51b of each fiber entanglement device 51. By the injection of the pressurized fluid, a large number of fibers in the two fiber bundles FB1 and FB2 are entangled with each other between the fiber bundle clamp devices 52 to form joints, and the relaxed fiber bundles FB1 and FB2 The slack disappears. Further, as the fluid to be ejected, a fluid or gas that can be supplied under pressure is used. As the fluid to be ejected, air is usually used from the viewpoint of workability and economy.

A mechanism of forming the yarn joining portion A will be described with reference to FIGS. 6, 7, and 8. FIG. FIG. 6 is a schematic cross-sectional view of an example of the fiber entanglement device 51. 7 is an S1-S1 cross-sectional arrow view of the fiber entanglement device 51 of FIG. FIG. 8 is a schematic side view illustrating a state in which one yarn splicing joint is formed by the fiber entanglement device of FIG.

The fiber entanglement device 51 is formed by an upper fiber entanglement device 51a and a lower fiber entanglement device 51b. Each of the upper fiber entanglement device 51a and the lower fiber entanglement device 51b includes a first fluid ejection hole array including a plurality of fluid ejection holes arranged at intervals on a first straight line perpendicular to the longitudinal direction of the fiber bundle. 71 and a plurality of fluid ejection holes that are spaced from each other in the longitudinal direction of the fiber bundle with respect to the first straight line and arranged on the second straight line parallel to the first straight line. Two fluid ejection hole arrays 72 are provided.

Each fluid injection hole of the first fluid injection hole row 71 and the second fluid injection hole row 72 in the upper fiber entanglement device 51a is opened on the lower surface of the upper fiber entanglement device 51a. Each fluid injection hole of the first fluid injection hole row 71 and the second fluid injection hole row 72 in the lower fiber entanglement device 51b is opened on the upper surface of the lower fiber entanglement device 51a. A fluid treatment chamber FC is formed between the lower surface of the upper fiber entanglement device 51a and the upper surface of the lower fiber entanglement device 51a.

Upstream of each fluid ejection hole in the first fluid ejection hole row 71 and the second fluid ejection hole row 72 in the upper fiber entanglement device 51a is a pressurized fluid supply path FS provided in the upper fiber entanglement device 51a. Communicating with Upstream of each fluid ejection hole of the first fluid ejection hole row 71 and the second fluid ejection hole row 72 in the lower fiber entanglement device 51b is a pressurized fluid supply path FS provided in the lower fiber entanglement device 51b. Communicating with

When pressurized fluid (pressurized air) is ejected from each fluid ejection hole, a jet of pressurized fluid having a thin and strong linear velocity is obtained, and a plurality of uniform fluid vortices are created in the pressurized fluid processing chamber FC. Each fluid injection hole is disposed so as to be generated. By spraying the pressurized fluid, a large number of fibers of the two fiber bundles FB1 and FB2 can be finely opened to the single fiber level. The fiber opening part B is formed by the fiber opening.

A large number of opened fibers form an entanglement toward the fiber entanglement device 51 with the fiber bundle clamp device 52 to which the fiber bundle is fixed as a base point. The multiple fibers of the two fiber bundles FB1 and FB2 are divided into small bundles by a plurality of uniform fluid vortices formed in the pressurized fluid processing chamber FC, and a plurality of partially entangled portions D are formed. By injecting pressurized fluid (pressurized air) that is uniformly thin in the width direction of the fiber bundle and has a strong linear velocity, the number of filaments contained in each small bundle can be made the same, and the fiber bundle A plurality of partially entangled portions D that are uniform in the width direction are formed. That is, a fiber entangled portion C having a plurality of partially entangled portions D with little variation in binding strength is formed.

Next, in order to form the fiber opening part B which becomes a heat radiating part that can release heat to the outside, the fiber entanglement device 51 has two rows of fluid jets arranged in parallel in the longitudinal direction of the fiber bundle. It is necessary to have a hole array. Since there is no base point necessary for fiber entanglement between the two rows of injection holes, there is no entanglement between the fibers between the two rows of injection holes. It becomes in a fine state. That is, the space between the two rows of injection holes is an ineffective space with respect to the entanglement effect of the fibers. Therefore, as shown in FIG. 8, the fiber opening part (heat radiating part) B is provided between the two rows of fluid ejection holes, and the fiber entangled part is provided between the fiber entanglement device 51 and the fiber bundle clamp device 52. C is formed.

Thus, in order to obtain the yarn splicing joint portion having both the fiber opening portion (heat radiating portion) B and the fiber entanglement portion C, the fiber entanglement device 51 is arranged in parallel at intervals in the longitudinal direction of the fiber bundle. It is necessary to have two rows of fluid ejection holes 71 and 72 positioned at the same time. When the fluid ejection hole array opened on the lower surface of the upper fiber entanglement device 51a and the upper surface of the lower fiber entanglement device 51b is one row, a large number of fibers forming the fiber bundle are opened. Can not be in the state.

In this case, since the fiber entanglement is formed up to the center of the fiber bundle located between the adjacent fiber bundle clamp devices 52, it is not possible to form a fiber opening part (heat dissipating part) that can release heat to the outside. Even if the number of fluid ejection hole rows is one, it is possible to shorten the entanglement processing time and apparently form the fiber opening part (heat dissipating part), but in this case, the entanglement processing time is short. Therefore, a fiber entangled portion having sufficient binding strength cannot be formed, and the fiber bundle is easily broken during the process. When there are three or more fluid ejection hole rows, not only the amount of pressurized air increases, but also the fiber bundle of the fiber opening part (heat dissipating part) is damaged by the pressurized fluid (pressurized air). The fiber bundle is easily broken during passage.

The length (row interval) L in the longitudinal direction of the fiber bundle between the two fluid

ejection hole rows

71 and 72 is preferably 20 to 100 mm, and more preferably 25 to 55 mm. When the length L is less than 20 mm, the fiber opening part (heat dissipating part) becomes small, and it is difficult to obtain a fiber opening part (heat dissipating part) having a sufficient heat dissipation effect, and the length L exceeds 100 mm. The fiber opening part (heat radiation part) becomes larger than necessary.

The arrangement pitch P of the fluid ejection holes in the fluid ejection hole array is preferably 1.7 to 4.5 mm, and the hole diameter HD of the fluid ejection holes is preferably 1.2 to 2.5 mm. Considering the accuracy of machining the fluid ejection holes, a certain thickness is required between the ejection holes, and the arrangement pitch P of the fluid ejection holes may be 0.5 mm or more larger than the hole diameter HD. preferable.

When the arrangement pitch P of the fluid injection holes is less than 1.7 mm, a jet of compressed air having a thin and strong linear velocity cannot be obtained and a slit-like jet is obtained, so that the fiber bundle is opened to the single fiber level, In addition, the fiber entangled part may not be formed.

When the arrangement pitch P of the fluid ejection holes exceeds 4.5 mm, the size of each partial entanglement increases, and the number of filaments included in each partial entanglement portion increases, so heat storage may not be suppressed.

As for the hole diameter HD of the fluid injection hole, when the hole diameter HD of the fluid injection hole is small, a jet of pressurized fluid (pressurized air) having a sufficient linear velocity cannot be obtained, the fiber bundle is opened, and The fiber entangled part may not be formed. When the diameter HD of the fluid ejection hole is large, the thickness of the jet of pressurized fluid (pressurized air) ejected from each fluid ejection hole is increased, so that a large number of fibers are opened to the single fiber level. In some cases, the fiber opening is insufficient and a sufficient heat dissipation effect cannot be obtained.

The pressure of the pressurized fluid (pressurized air) is preferably 0.3 to 0.6 MPa. When the pressure is less than 0.3 MPa, opening of a large number of fibers forming the fiber bundle becomes insufficient, and it may be difficult to form a fiber entangled part having a plurality of partially entangled parts. . When the pressure exceeds 0.6 MPa, the fiber bundle is damaged by the pressurized fluid, and the fiber bundle is easily broken.

It is possible to form a single yarn splicing joint by dividing a plurality of fiber bundles into a plurality of fiber bundles in the width direction in advance and using a plurality of fiber entanglement devices. However, not only the workability is deteriorated, but also when dividing the fiber bundle, the fiber bundle becomes fluffy and the bonding strength is reduced, so that the fiber bundle is not divided into a plurality of fiber bundles in the width direction. It is preferable to perform the fiber entanglement process at once with one fiber entanglement device.

Each of the first fiber bundle FB1 and the second fiber bundle FB2 is preferably a precursor fiber bundle for producing carbon fibers.

FIG. 2 or FIG. 3 is a schematic longitudinal sectional view of an example of a fiber bundle having a yarn splicing joint portion of the present invention in which the respective precursor fiber bundles are joined via a connecting fiber bundle (connecting medium).

In an embodiment using a connecting fiber bundle (connecting medium), the connecting fiber bundle preferably has a thermal conductivity of 3 to 700 W / m · K. In the embodiment using this connecting fiber bundle (connecting medium), the connecting fiber bundle has a calorific value of 500 cal / g or less at an ambient temperature of 150 to 400 ° C., and a thermal conductivity of 3 to 700 W / m. -K is preferred. In addition to this preferable condition, the connecting fiber bundle has a single fiber number (number of filaments) of a large number of fibers forming the connecting fiber bundle of 3,000 or more and a drape value of the connecting fiber bundle of 2 to 15 cm. And it is preferable that the flatness is 20 or more.

When this connecting fiber bundle is used, for example, the end portion 5 of the first fiber bundle FB1 and one end portion of the connecting fiber bundle JFB are overlapped, and the other end portion of the connecting fiber bundle JFB and the second end portion are connected. The fiber bundle FB2 is overlapped with the start end portion 6 and the overlapped portion is accommodated in the fiber entanglement device 51. Each end portion and the connecting fiber bundle are preferably overlapped by 350 to 500 mm in the longitudinal direction of the fiber bundle.

At this time, by using a connecting fiber bundle that is non-exothermic (a calorific value is 500 cal / g or less) and has a thermal conductivity of 3 to 700 W / m · K, the yarn splicing joint A during the flameproofing treatment In addition to greatly reducing the amount of heat generated at the center, the heat removal of the amount of heat stored in the fiber entangled portions of the first fiber bundle FB1 and the second fiber bundle FB2 during the flameproofing process is also promoted. Therefore, yarn breakage due to heat storage can be greatly reduced. As the connecting fiber bundle, a carbon fiber bundle is preferably used.

The number of single fibers (the number of filaments) of a large number of fibers in the yarn splicing joint A is preferably 3,000 to 100,000. More preferably, it is 12,000 to 60,000. The fineness of the single fiber (filament) is preferably 0.8 to 1.7 dtex (0.7 to 1.5 denier).

This yarn splicing joint A is particularly effective for yarn splicing of the polyacrylonitrile-based precursor fiber bundle, and the polyacrylonitrile-based precursor fiber bundle having this yarn splicing joint is formed by heat storage when passing through the firing step. There is no yarn breakage, there is no need to lower the temperature in the flameproofing furnace, and it is suitable for continuously producing carbon fibers.

The fiber bundle having the yarn splicing joint A shown in FIG. 2 and FIG. 3 includes a first precursor fiber bundle (first fiber bundle) FB1 and a second precursor fiber bundle (second fiber bundle). A third fiber bundle (connecting fiber bundle) JFB is bridged between the FB2 and each of them, and is bonded to each other. As this connecting fiber bundle JFB, a carbon fiber bundle having a thermal conductivity of 3 to 700 W / m · K, a filament number of 3000 or more, a drape value of 2 to 15 cm, and a flatness of 20 or more is preferably used. .

In the joint portion between the precursor fiber bundle and the carbon fiber bundle, the yarn splicing joint portion A is formed at a portion where the respective multiple fibers in the first precursor fiber bundle FB1 and the carbon fiber bundle JFB are entangled with each other. . In addition, a yarn splicing joint A is formed at a portion where the multiple fibers in the carbon fiber bundle JFB and the second precursor fiber bundle FB2 are entangled with each other.

The fiber bundle having the yarn splicing joint shown in FIG. 2 includes an overlapping portion of the first precursor fiber bundle FB1 and the carbon fiber bundle JFB, and an overlapping portion of the carbon fiber bundle JFB and the second precursor fiber bundle FB2. In addition, one yarn splicing joint A is provided for each. The larger the number of yarn splicing joints, the more stable the tensile strength of the whole joint, but if you try to create a plurality of yarn splicing joints at the same time, the equipment will increase in size. Cost increase. Equipment for creating one yarn splicing joint may be used multiple times, but there is a problem that the number of operations increases. The number of yarn splicing joints is preferably two, or three or four as shown in FIG.

The

end portions

4a and 4b of the connecting fiber bundle FJB, the end portion 5 of the first precursor fiber bundle FB1, and the end portion 6 of the second precursor fiber bundle 1 to 1 from the end of the yarn splicing joint A. It is preferable to cut it so that it is located at about 5 cm. The precursor fiber bundle may be shrunk by heat treatment in a flameproofing furnace, and in order to prevent unraveling of the fiber entanglement part, it is preferable that the position of the end part is adjusted leaving a length of about 1 cm. . When the length is longer than 5 cm, it is not preferable because it may cause troubles such as fiber mixing to the fiber bundle running next to the firing step.

The connecting fiber bundle is a carbon fiber bundle having a thermal conductivity of 3 to 700 W / m · K or less, a number of filaments of 3,000 or more, and a drape value of 2 to 15 cm. The flatness of the bundle is preferably 20 or more.

The number of filaments in the connecting fiber bundle can be appropriately selected according to the number of filaments in the precursor fiber bundle to be entangled. However, when the number of filaments is less than 3,000, the connecting fiber bundle and the precursor fiber bundle are not sufficiently entangled, and the fiber bundle may break due to the tension during the firing process. The increase in the number of filaments is useful for efficient heat removal of the reaction heat generated from the precursor fibers in the flameproofing furnace, but if the number of filaments is increased too much and the fiber bundle becomes too thick, the connecting fiber bundle and the precursor are increased. The fiber entangled part with the fiber bundle becomes too thick, and there is a possibility that problems such as fiber mixing may occur between the fiber bundle running adjacent to the fiber bundle, which is not preferable. Therefore, the number of filaments is preferably 100,000 or less.

When the thermal conductivity of the carbon fiber bundle used for the connecting fiber bundle is less than 3 W / m · K, the heat generated in the yarn splicing joint cannot be sufficiently dissipated at the time of flame resistance, that is, the heat removal effect is low. The fiber bundle will be broken due to heat storage. Further, if the thermal conductivity of the carbon fiber bundle exceeds 700 W / m · K, the elastic modulus of the fiber bundle is too high, and the spliced joint is not formed well, and the effect of high heat removal is offset. . The thermal conductivity of the carbon fiber bundle is more preferably 7 to 50 W / m · K.

The thermal conductivity is calculated by the following formula 1 based on the thermal diffusivity, density, and specific heat of the fiber bundle shown below.

λ = αρCp (Formula 1)
λ: thermal conductivity (W / (m · k))
α: Thermal diffusivity (m ² / s)
This thermal diffusivity was calculated according to the optical alternating current method described in the following document. T. T. Yamane, S .; Katayama, M .; Todoki and I.I. Hatta: J.M. Appl. Phys. , 80 (1996) 4385.

ρ: Density (kg / m ³ )
This density is the weight W ₁ in air of the object _(kg), and, based on the weight W _{2 (kg)} in the liquid in the time of sinking the object to be measured in a liquid of density [rho _L This is calculated by the following equation 2.

ρ = W ₁ × ρ _L / (W ₁ −W ₂ ) (Formula 2)
Cp: Specific heat (J / (kg · K))
This specific heat value was measured with a DSC (Differential Scanning Calorimeter) at a measurement temperature of 25 ° C. with reference to JIS-R1672. The DSC is sufficient if it has a function equivalent to that of Perkin-Elmer DSC-7. As standard data, sapphire (α-Al 2 O 3) and aluminum containers can be used.

In addition, the thermal diffusivity and specific heat of the fiber bundle are the average values of the values measured at the number of measurements of 2, and the density at the number of measurements of 6, respectively.

When the drape value of the connecting fiber bundle exceeds 15 cm, the fiber bundle becomes too hard, and therefore, during the fiber entanglement process using the pressurized fluid, a large number of fibers forming the connecting fiber bundle are difficult to spread each other. Between a plurality of fibers forming one precursor fiber bundle and a plurality of fibers forming a second precursor fiber bundle and a plurality of fibers forming a connecting fiber bundle The entanglement is not evenly applied. For this reason, the drape value of the connecting fiber bundle is preferably 10 cm or less, and more preferably 8 cm or less.

The drape value is a value representing the hardness of the fiber bundle. It can be said that the smaller the value, the softer the fiber bundle and the smaller the shape retention. The lower limit of the drape value of the connecting fiber bundle is preferably 2 cm. That is, as the number of fibers spreads easily and the fiber bundle is relatively soft as a whole, fiber entanglement is more likely to occur. However, if the drape value is less than 2 cm, the fiber bundle is too soft and its handling becomes difficult. In addition, since a large number of fibers are likely to spread, each single yarn effective for heat removal is likely to break at the time of joining with the precursor fiber bundle, and the tensile strength to withstand the process tension is also reduced, so the drape value is 2 cm or more It is preferable that

There are various means for controlling the drape value, but typically it can be controlled by the amount of sizing agent applied to the connecting fiber bundle. If the adhesion amount of the sizing agent is increased, the drape value is increased, and if it is decreased, the drape value is decreased. Therefore, the drape value of the connecting fiber bundle can be adjusted to a desired value.

A drape value measuring method will be described with reference to FIGS. First, a measurement sample having a length SL of about 50 cm is cut out from a connecting fiber bundle (carbon fiber bundle) to prepare a measurement sample. FIG. 9 is a schematic side view of an apparatus for creating a measurement sample for preparing a measurement piece used when measuring a drape value. In FIG. 9, a measurement sample creating apparatus 90 has a sample fixing portion 91 for fixing the upper end of the measurement sample at the upper part thereof. The upper end of the prepared measurement sample 92 is fixed to the sample fixing portion 91, and the measurement sample 92 is suspended.

Next, a weight 93 is attached to the lower end of the measurement sample 92 so that a tension of 0.0375 g / tex acts on the measurement sample 92. Thereafter, the inside of the measurement sample preparation apparatus 90 is maintained in an atmosphere having a temperature of 23 ° C. and a humidity of 60%. In this atmosphere, the measurement sample 92 is left for 30 minutes or more. Thereafter, the measurement sample 91 is taken out from the measurement sample creation device 90. The upper and lower end portions of the obtained measurement sample 91 are removed, and a measurement piece having a length TL of 30 cm is prepared.

FIG. 10 is a schematic side view of a drape value measuring apparatus that measures a drape value using a measurement piece cut out from the measurement sample obtained in FIG. In FIG. 10, a drape value measuring apparatus 100 is attached to a rectangular column 102 fixed vertically to the upper surface of a base 101 and the upper surface of the rectangular column 102 so as to be detachable, and is perpendicular to the vertical side surface of the rectangular column 102. It consists of a protruding flat plate 103.

In the drape value measuring apparatus 100, one end of the previously prepared measurement piece TP is fixed to the upper surface of the quadrangular column 102, and the measurement piece TP is placed on the upper surface of the flat plate 103. Thereby, the measurement piece TP is positioned so as to be parallel to the upper surface of the base 101 so as not to hang down in a cantilever-supported state. The fixed length between the measurement piece TP and the upper surface of the quadrangular column 102 is 5 cm, and the protruding length DL from the vertical side surface of the quadrangular column 102 is 25 cm.

After the mounting of the measuring piece TP to the drape value measuring apparatus 100 is completed, the flat plate 103 is quickly removed from the quadrangular column 102. As shown in FIG. 11, the measurement piece TP that is no longer supported by the flat plate 103 hangs down due to gravity. The horizontal distance Ld (cm) between the tip (free end) of the measurement piece 103 and the vertical side surface of the quadrangular column 102 one second after the flat plate 103 is removed and the measurement piece TP starts to sag is defined as the drape value.

In the fiber bundle overlapping portion of the first precursor fiber bundle and the connecting fiber bundle, and in the fiber bundle overlapping portion of the second precursor fiber bundle and the connecting fiber bundle, between the fibers in the respective fiber bundle overlapping portions. In order to make the entanglement process more uniform, the flatness of the connecting fiber bundle (carbon fiber bundle) is preferably 20 or more. When the flatness is less than 20, the connecting fiber bundle becomes thin, so that the method of making a large number of fibers forming the connecting fiber bundle during the fluid entanglement process is likely to be non-uniform, and the yarn joining in the firing process This causes a decrease in the tensile strength of the joint and a decrease in the thread break temperature.

The upper limit of the flatness is about 200, and if it exceeds 200, the width of the fiber bundle becomes too wide. Therefore, the fibers forming the first precursor fiber bundle and the fibers forming the connecting fiber bundle are Entanglement spots between the fibers forming the second precursor fiber bundle and the fibers forming the connecting fiber bundle are likely to occur, and yarn joining in the firing step This leads to a decrease in the tensile strength of the joint.

The flatness of the connecting fiber bundle (carbon fiber bundle) is the size of the width W of the connecting fiber bundle with respect to the thickness T of the connecting fiber bundle, that is, W / T.

The width W (mm) of the connecting fiber bundle is a length in the width direction measured in a state where the connecting fiber bundle is left standing on a flat measurement table, and the value obtained by directly measuring the length in the width direction with a ruler. It is.

The thickness T (mm) of the connecting fiber bundle is such that the single yarn fineness Y (g / m), density ρ (kg / m ³ ) of each filament in the multiple filaments forming the connecting fiber bundle, and the connecting fiber bundle Based on the number F of formed filaments and the width W (mm) of the connecting fiber bundle, this is a value calculated from the following equations 3 and 4.

D (mm) = √ (4 × Y × 10 ³ / (π × ρ)) (Formula 3)
T (mm) = F × D ² / W (Formula 4)
The fineness of the connecting fiber bundle is preferably 0.2 to 3.0 times the fineness of the first precursor fiber bundle or the second precursor fiber bundle. If it is less than 0.2 times, the entanglement defect part in which the fibers of the connecting fiber bundle are not entangled easily occurs in the first precursor fiber bundle part and the second precursor fiber bundle part. When it exceeds 3.0 times, the confounding defect in which the fibers of the first precursor fiber bundle and the second precursor fiber bundle fiber are not entangled easily occurs in the connecting fiber bundle portion.

The fineness of the connecting fiber bundle is more preferably 0.3 to 1.2 times the fineness of the first precursor fiber bundle and the second precursor fiber bundle, and 0.4 to 0.8. More preferably, it is doubled. The fineness of both the first and second precursor fiber bundles is not only the same, but even if they are different, when the fineness of the connecting fiber bundle is in the preferred fineness range, it has a yarn splicing joint composed of these. The permeability of the fiber bundle firing process is good, and the fiber bundle can be continuously fired. That is, a continuous carbon fiber bundle can be manufactured.

It is preferable that the tensile strength in the normal temperature atmosphere of the junction part between a precursor fiber bundle and a carbon fiber bundle is 20 g / tex or more. The normal temperature refers to the working atmosphere in which the precursor fiber bundle and the carbon fiber bundle are joined, that is, the outside air temperature, specifically, 20 to 30 ° C. It is preferable that the tensile strength of the joint is 20 g / tex or more at all temperatures in this temperature range. It is more preferable that the tensile strength of the joint is 20 g / tex or more at all temperatures in the temperature range of about 5 ° C. to about 50 ° C.

When the tensile strength of the bonded portion is less than 20 g / tex at any temperature in such a temperature range, the bonded portion may not withstand the tension in the firing process, and a trouble that breaks may occur. A higher tensile strength at the joint is preferable from the viewpoint of the passability of the firing process. However, if the fiber entanglement is to be strengthened in order to increase the tensile strength of the joint, the precursor fiber bundle and carbon Each filament of the fiber bundle may break. It is sufficient that the tensile strength of the joint is about 50 g / tex.

Tensile strength is determined by using a tensile tester (a tensile tester having the ability of about ORIENTEC (model: RTC-1225A)), and the tensile strength between both ends where the precursor fiber bundle and the carbon fiber bundle are joined, It is a value obtained by dividing the maximum value measured at a tensile speed of 100 mm / min by the fineness (tex) of the broken fiber bundle in the first or second precursor fiber bundle.

The carbon fiber bundle used for the connecting fiber bundle has a thermal conductivity of 3 to 700 W / m · K, the number of filaments forming it is 3,000 or more, and the drape value is By satisfying all that the flatness is 2 to 15 cm and the flatness is 20 or more, the fiber bundle having the yarn splicing joint made of this exhibits extremely excellent passability in the firing step.

Carbon fiber bundles having a thermal conductivity of 3 to 700 W / m · K and a filament number of 3,000 or more are carbonized or carbonized depending on the number of filaments of the precursor fiber bundle and the conditions for firing it. It can be manufactured by adjusting the degree of graphitization.

An example of a preferable method for producing a carbon fiber bundle used as a connecting fiber bundle having a drape value of 2 to 15 cm and a flatness of 20 or more is as follows. As a precursor fiber, a polyacrylonitrile fiber bundle spun using polyacrylonitrile as a raw material is once wound up on a bobbin and prepared. The prepared polyacrylonitrile fiber bundle is pulled out from the bobbin, subjected to a flame resistance treatment at 230 to 280 ° C. in the air, and then carbonized in a carbonization furnace controlled to a maximum temperature of 1,900 ° C. or less to obtain a carbon fiber. A bundle. If necessary, the obtained carbon fiber bundle can be heated to a maximum temperature of 1,900 to 2,600 ° C. to obtain a graphitized fiber bundle.

After applying the sizing agent to the carbon fiber bundle or graphitized fiber bundle thus obtained under a tension of 1.5 to 6.0 g / tex, preferably 2.0 to 5.5 g / tex. The fiber bundle is pressed against a hot roll controlled at a temperature of about 100 to 150 ° C., dried while being flattened, and wound up. By this step, a carbon fiber bundle having a drape value of 2 to 15 cm and a flatness of 20 or more is obtained. In addition, the sizing agent to be applied is not particularly limited, but in order to adjust the drape value to the above range, the adhesion amount, the adhesion method, and the drying temperature may be appropriately selected.

By using the carbon fiber bundle having such characteristics as the connecting fiber bundle, the heat generation of the fiber bundle in the flameproofing furnace can be efficiently removed, and the productivity of the desired carbon fiber can be greatly improved. I can do it.

Next, the present invention will be described using some examples. However, the present invention is not limited to these examples.

In the examples, the fiber bundle having the yarn splicing joint is allowed to pass through the flame-proofing furnace existing in the carbon fiber manufacturing process without causing yarn breakage, and the temperature inside the flame-proofing furnace is 245 ° C. At that time, the process tension that could pass without thread breakage was measured. Furthermore, as an index of operability, the process passage rate was measured at a flameproof furnace temperature of 245 ° C. and a process tension of 5 kg / st.

The flameproofing time of the fiber bundle in the flameproofing furnace was 60 minutes in all examples. The temperature inside the flameproofing furnace was adjusted in increments of 1 ° C. in consideration of the fluctuation range of temperature control. The number of samples was 20, and the number of samples that could pass the process was defined as the process pass rate.

The precursor fiber bundle used in the examples is a polyacrylonitrile-based precursor fiber bundle in which the fineness of one filament is 1.0 dtex (0.9 denier) and the number of filaments is 24,000. The results in each example and comparative example are shown in Table 1.

The end portion 5 of the first precursor fiber bundle FB1 and the end portion 6 of the second precursor fiber bundle FB2 were overlapped with the length of the fiber bundle overlapping portion being 400 mm. Using the yarn joining device shown in FIG. 5, both fiber bundles were joined at the fiber bundle overlapping portion. At this time, three fiber entanglement devices 51 were used. The diameter of the fluid ejection holes in each of the first fluid ejection hole array 71 and the second fluid ejection hole array 72 of each fiber entanglement device 51 was 1.5 mm, and the arrangement pitch of the fluid ejection holes was 2.5 mm. The length (row interval) L in the longitudinal direction of the fiber bundle between the fluid

ejection hole rows

71 and 72 was 30 mm. The superposed first and second fiber bundles FB1 and FB2 were given a relaxation of 9.0% by a fiber bundle relaxation device 53 using a round bar.

Then, pressurized air with a pressure of 0.4 MPa was jetted from the fluid jet hole for 2 seconds. As a result, three yarn joining portions were formed in the fiber bundle. Each formed yarn splicing joint A was provided with one fiber opening part (heat dissipating part) B and two fiber entangled parts C. The length X of each fiber opening part (heat dissipating part) B is 42 mm, and the length in the width direction of each fiber opening part (heat dissipating part) is 1. of the length in the width direction of the fiber bundle before opening. It was 6 times. Each fiber entangled portion C had four partially entangled portions D. The length Y of each fiber entangled portion C was 14 mm.

On the other hand, the same precursor fiber bundle without a yarn splicing joint, that is, a continuous fibril bundle, was subjected to flame resistance treatment using the same flame resistance furnace.

Table 1 shows the results of the flameproofing treatment of the continuous fibril bundle and the results of the flameproofing treatment of the continuous fiber bundle having the yarn splicing joint of Example 1. Compared with the continuous fibril bundle, in the case of the continuous fiber bundle having the yarn splicing joint of Example 1, the temperature that can pass through the flameproofing furnace is reduced by about 10 ° C., but the reduction width greatly increases the operability. It was confirmed that it was not reduced. The process tension which can be passed was 7 kg / st, and the process passing rate was 95%. Further, it was confirmed that the bonded portion after firing maintained a flat and uniform bonding form. This means that fiber mixing between fibers did not occur between adjacent fiber bundles.

The first precursor fiber bundle FB1 and the second precursor fiber bundle FB2 were the same as those in Example 1. Separately, a connecting fiber bundle JFB composed of carbon fiber bundles having a filament number of 24,000 and a thermal conductivity of 55 W / m · K was prepared. The three prepared fiber bundles were superposed in the state shown in FIG. The length of the overlapping portion of the first precursor fiber bundle FB1 and the carbon fiber bundle JFB and the length of the overlapping portion of the second precursor fiber bundle FB1 and the carbon fiber bundle JFB were each 400 mm. The distance between the end of the first precursor fiber bundle FB1 and the end of the second precursor fiber bundle FB2 was 500 mm.

The first precursor fiber bundle FB1 and the carbon fiber bundle JFB and the second precursor fiber bundle FB1 and the carbon fiber bundle are used in each fiber bundle overlapping portion by using the yarn splicing device shown in FIG. JFB was joined. At this time, the same three fiber entanglement devices 51 used in Example 1 were used. In the same manner as in Example 1, the overlapped fiber bundle was given a relaxation of 9.0% by a fiber relaxation device 53 using a round bar.

Thereafter, pressurized air having a pressure of 0.4 MPa was ejected from the fluid ejection holes for 2 seconds in the same manner as in Example 1. As a result, three yarn splicing joints are provided between the first fiber bundle FB1 and the carbon fiber bundle JFB, and three yarn splicing joints are provided between the second fiber bundle FB2 and the carbon fiber bundle JFB. Formed. Each formed yarn splicing joint A was provided with one fiber opening part (heat dissipating part) B and two fiber entangled parts C. The length X of each fiber opening part (heat dissipating part) B is 42 mm, and the length in the width direction of each fiber opening part (heat dissipating part) is 1. of the length in the width direction of the fiber bundle before opening. It was 6 times. Each fiber entangled portion C had four partial entangled portions D. The length Y of each fiber entangled portion C was 14 mm. Note that the carbon fiber bundle located in the section between the end of the first precursor fiber bundle FB1 and the end of the second precursor fiber bundle FB2 is not subjected to the injection of pressurized air.

Table 1 shows the results of flameproofing treatment of continuous fiber bundles having yarn splicing joints using connecting fiber bundles (carbon fiber bundles) in this example. This continuous fiber bundle had a temperature at which the continuous fiber bundle could pass through a flameproofing furnace. Therefore, it was possible to pass the joint without lowering the furnace temperature of the flameproofing furnace. The process tension that can be passed was 7 kg / st, and the bonding strength between fibers was sufficient at the joint, and the process passing rate was 100%. The state of the joint after passing through the process was also good.

Comparative Example 1

A fiber bundle in which a first fiber bundle FB1 and a second fiber bundle FB2 similar to those in Example 1 were overlapped was prepared. The prepared fiber bundles were joined to each other at the fiber bundle overlapping portion using the yarn joining device shown in FIG. At this time, three fiber entanglement devices 51 were used. The fluid ejection hole row in each fiber entanglement device 51 is one row. The diameter of the fluid ejection holes was 3.0 mm, and the arrangement pitch of the fluid ejection holes was 6.0 mm. 7.0% relaxation was imparted to the superposed first and second fiber bundles FB1 and FB2 by a fiber bundle relaxation device 53 using a round bar.

Thereafter, pressurized air having a pressure of 0.4 MPa was jetted from the fluid jet holes for 2 seconds. As a result, three yarn joining portions were formed in the fiber bundle. In each formed yarn splicing joint, there was no fiber opening part (heat radiation part), and one fiber entangled part was formed. Each formed fiber entangled part had two partial entangled parts. The length Y of each fiber entangled portion was 5 mm.

The continuous fiber bundle having the yarn splicing joint in this comparative example is easily burnt out in the flame resistant furnace because the joint is difficult to remove heat. Therefore, the temperature that can pass through the flameproofing furnace is 240 ° C., and the temperature that can pass through the flameproofing furnace is greatly reduced as shown in Table 1 compared to the continuous fibril bundle. Since the variation of the fiber entanglement in each partially entangled portion is large, the process tension that can be passed is reduced to 5 kg / st, and the process pass rate is also not preferable at 80%.

The embodiment described below is an embodiment that adopts a part of the conditions different from the above embodiment.

As a condition of the flameproofing furnace, air is flowed so that the wind speed in the furnace is 1.0 m / sec in a direction perpendicular to the traveling direction of the precursor fiber bundle, and the tension applied to the traveling fiber bundle in the furnace is It adjusted so that it might be set to 1.5 g / tex. The upper limit temperature at which the yarn splicing joint in this flameproofing furnace can pass was measured.

The precursor fiber bundle used is a polyacrylonitrile-based precursor which is a multiplicity of substantially untwisted fibers, the fineness of a single fiber (one filament) is 1.1 dtex, and the number of filaments is 24,000. It is a fiber bundle. The results are shown in Table 2 for each of the following examples.

At each end facing each other with a gap between the first precursor fiber bundle FB1 and the second precursor fiber bundle FB2, there is a connecting fiber bundle JFB with 48,000, 24,000, and 12,000 filaments, respectively. A certain carbon fiber bundle was overlapped and joined, and three types of fiber bundle samples having a yarn joining portion were prepared. At this time, in joining the overlapped fiber bundle, first, a relaxation amount of 9.0% is given to the overlapped fiber bundle in the longitudinal direction, and then, in the overlap portion, Three fiber entanglement devices 51 were used to join the fiber bundles. Each fiber entanglement device 51 has a first fluid ejection hole row 71 and a second fluid ejection hole row 72. A large number of jetted air having a pressure of 0.4 MPa is jetted from the fluid jet holes arranged at intervals in each fluid jet hole row for 2 seconds, and each fiber bundle is formed in each overlapping portion. The fibers of the book were entangled. Thereby, the fiber bundle 3 which has the thread splicing junction part shown in FIG. 3 which has the three thread splicing junction parts A in each overlapping part was created. Each yarn splicing joint A had two fiber entangled portions C positioned at intervals and a fiber opening portion (heat radiating portion) positioned between the two fiber entangled portions C.

As shown in Table 2, each fiber bundle sample (a), (b), (c) has a temperature at which it can pass through a flameproofing furnace as compared to a reference example of a continuous fibril bundle without a fiber bundle joint. To the extent that the temperature decreases by 0 to 1 ° C., the range of decrease in the temperature at which the joint can pass through the flameproofing furnace was small. Each fiber bundle sample (a), (b), (c) having a joint was run to each step after the flameproofing furnace, but finally including not only the flameproofing step but also the carbonization step. Until the fiber bundle was wound on a bobbin attached to a winder, no yarn breakage due to heat storage or tension during the process was observed. Therefore, without changing the production conditions, the start end of the new fiber bundle can be spliced to the end of the fiber bundle that has been previously introduced into the firing process, and the production efficiency of carbon fibers can be greatly improved. Was made.

In this example, the carbon fiber bundle used as the connecting fiber bundle was changed to that shown in Table 2, and the fiber bundle was fired in the same manner as in Example 3 (b). As a result, the temperature that can pass through the flameproofing furnace decreased by 3 ° C compared to the reference example, and some yarn breakage due to tension was observed even in the carbonization process, but it was of a level that could sufficiently withstand the production of carbon fiber. It was confirmed that.

In this example, as shown in FIG. 2, the fiber bundle was fired in the same manner as in Example 3 (a) except that the number of joints was set to 1. As a result, the temperature that can pass through the flameproofing furnace decreased by 4 ° C compared to the reference example, and some yarn breakage due to the tension was observed even in the carbonization process, but it was of a level that could sufficiently withstand the production of carbon fiber. It was confirmed that.

The carbon fiber bundle used as the connecting fiber bundle is as shown in Table 2, and the fineness ratio of the precursor fiber bundles FB1, FB2 and the carbon fiber bundle JFB was set to 3.09, as in Example 3, Firing of the fiber bundle was performed. As a result, the temperatures that allowed passage through the flame-proofing furnace decreased by 5 ° C compared to the reference example, and yarn breakage was observed even in the carbonization process, but it was confirmed that the temperature could withstand carbon fiber production. It was.

The carbon fiber bundle used as the connecting fiber bundle is as shown in Table 2, and the same as in Example 3 except that the fineness ratio of the precursor fiber bundles FB1, FB2 and the carbon fiber bundle JFB was 0.15. Firing of the fiber bundle was performed. As a result, the temperatures that allowed passage through the flame-proofing furnace decreased by 5 ° C compared to the reference example, and yarn breakage was observed even in the carbonization process, but it was confirmed that the temperature could withstand carbon fiber production. It was.

This example is an example when the drape value of the carbon fiber bundle of the connection fiber bundle is 20 cm which is outside the preferable drape value range of 2 to 15 cm. The fiber bundle was fired in the same manner as in Example 3 (b) except that the drape value of the carbon fiber bundle was 20 cm. Since the drape value is high, the carbon fiber bundle is hard, and a large number of fibers forming it are difficult to spread. Therefore, compared with the case of Example 3 (b), it is difficult to obtain sufficient entanglement with the fibers forming the precursor fiber bundle, and the tensile strength of the joint portion is lowered. As a result, the upper limit temperature that allowed passage through the flameproofing furnace was 253 ° C.

This example is an example when the drape value of the carbon fiber bundle of the connection fiber bundle is 1 cm which is outside the preferable drape value range of 2 to 15 cm. The fiber bundle was fired in the same manner as in Example 3 (b) except that the drape value of the carbon fiber bundle was 1 cm. As a result, the carbon fiber bundle, which is the connecting fiber bundle, has a low drape value, so that the fiber bundle is excessively burned, its handleability is deteriorated, and the time required for the yarn joining operation is increased. The upper limit temperature that can pass through the flameproofing furnace was 254 ° C., and the degree of the decrease was small.

This example is an example in which the flatness outside the range of the preferred flatness 20 or more of the carbon fiber bundle of the connecting fiber bundle is 14. The fiber bundle was fired in the same manner as in Example 3 (b) except that the flatness of the carbon fiber bundle was set to 14. As a result, as in the case of Example 8, a large number of fibers forming a carbon fiber bundle are difficult to spread. Therefore, compared with the case of Example 3 (b), it is difficult to obtain sufficient entanglement with the fibers forming the precursor fiber bundle, and the tensile strength of the joint portion is lowered. As a result, the upper limit temperature that allowed passage through the flameproofing furnace was 253 ° C.

This example is an example when the thermal conductivity outside the range of the preferable thermal conductivity of 3 to 700 W / m · k of the connecting fiber bundle is 1 W / m · k. The fiber bundle was fired in the same manner as in Example 3 except that a flame-resistant fiber bundle having 24,000 filaments was used as the connecting fiber bundle having a thermal conductivity of 1 W / m · k. Since the thermal conductivity of the connecting fiber bundle is low, the heat radiation of the joint in the flameproofing furnace is not sufficient, and yarn breakage due to heat storage is likely to occur. As a result, the upper limit temperature that allowed passage through the flameproofing furnace was 252 ° C.

According to the fiber bundle having the yarn splicing joint of the present invention, when the fiber bundle is continuously fired in the firing step, in the firing step, the fiber bundle is broken or the fiber forming the fiber bundle is There is an effect that heat storage at the yarn joining portion is suppressed and that heat removal at the yarn joining portion is good without coming off from the fiber bundle. Therefore, the temperature in the furnace in the firing process that is usually employed when the fiber bundle that does not have the yarn splicing joint, or the fiber bundle having the yarn splicing joint but other than that portion passes through the firing process. Without significantly lowering the fiber bundle having the yarn splicing joint of the present invention can be continuously passed through the firing process, so that the fired fiber, Carbon fiber can be produced continuously for a long time. The result is a significant increase in the productivity of fired fibers, such as carbon fibers.

1: Fiber bundle having a yarn joining portion 2: Fiber bundle having a yarn joining portion 3: Fiber bundle having a yarn joining portion 4a: One end portion 4b: The other end portion 5: End portion (terminal portion)
6: End (starting end)
50: Yarn splicing device 51: Fiber entanglement device 51a: Upper fiber entanglement device 51b: Lower fiber entanglement device 52: Fiber bundle clamping device 53: Fiber bundle relaxation device 71: First fluid ejection hole array 72: Second fluid ejection Hole array 90: Drapeability measurement sample preparation device 91: Sample fixing device 92: Measurement sample 93: Weight 100: Drape value measurement device 101: Base 102: Square pillar 103: Flat plate A: Yarn splicing joint B: Fiber opening part C: Fiber entangled part D: Partially entangled part DL: Projection length of the measurement piece of the drape value from the quadrangular column FB1: First fiber bundle FB2: Second fiber bundle FC: Pressurized fluid treatment chamber FS: pressurized fluid supply path H: heat HD: hole diameter of fluid injection hole HR: heat dissipation JFB: connection fiber bundle (carbon fiber bundle)
L: Length in the longitudinal direction of the fiber bundle between adjacent fluid ejection hole rows (row spacing)
Ld: drape value (distance)
P: arrangement pitch of fluid injection holes SL: length of sample for drape value measurement TL: length of measurement piece of drape value TP: measurement piece of drape value X: length in the longitudinal direction of fiber bundle at fiber opening portion Y: Length in the longitudinal direction of the fiber bundle at the fiber entanglement portion

Claims

One end portion of the first fiber bundle composed of a large number of fibers and one end portion of the second fiber bundle composed of a large number of fibers overlap each other, or Two fibers formed such that one end of the first fiber bundle made of fibers and one end of the second fiber bundle made of many fibers overlap each other on a connecting fiber bundle made of many fibers A plurality of fiber entangled portions having a bundle overlapping portion, wherein the fiber bundle overlapping portions are in an intertwined state with the fibers positioned at intervals in the longitudinal direction of the fiber bundles; Each of the fibers located between the plurality of fiber entangled portions has a fiber spread portion in a state where each fiber is opened, and each of the fiber entangled portions is the fiber bundle overlapping portion. The multiple fibers of one fiber bundle in And the plurality of fibers of the other fiber bundle are entangled with each other, consisting of a plurality of partially entangled portions that are located at intervals in the width direction of each fiber bundle, and the plurality of fiber entangled portions, The fiber bundle which has the thread splicing junction part in which each said fiber bundle is joined in the said fiber bundle superimposition part.
The fiber bundle according to claim 1, wherein each of the first fiber bundle and the second fiber bundle is a precursor fiber bundle for producing carbon fibers.
The fiber bundle according to claim 2, wherein the connecting fiber bundle has a thermal conductivity of 3 to 700 W / m · K.
The fiber bundle according to claim 3, wherein the connecting fiber bundle is a carbon fiber bundle, the drape value thereof is 2 to 15 cm, and the flatness thereof is 20 or more.
The fiber bundle according to claim 4, wherein the fineness of the connecting fiber bundle is 0.2 to 3.0 times the fineness of the first fiber bundle and the second fiber bundle.
The fiber bundle according to claim 4, wherein the tensile strength at normal temperature of the yarn splicing joint is 20 g / tex or more.
The length in the longitudinal direction of the fiber bundle of each fiber entangled portion is 8 to 30 mm, and the length in the longitudinal direction of the fiber bundle of the fiber opening portion is 30 to 100 mm. Fiber bundle.
One end portion of the first fiber bundle composed of a large number of fibers and one end portion of the second fiber bundle composed of a large number of fibers overlap each other, or Two fibers formed such that one end of the first fiber bundle made of fibers and one end of the second fiber bundle made of many fibers overlap each other on a connecting fiber bundle made of many fibers In the fiber bundle overlapping portion, each fiber is entangled by injecting a pressurized fluid from a fiber entanglement device to the fiber bundle overlapping portion of the fiber bundle having the bundle overlapping portion. In the manufacturing method of the fiber bundle which has the thread splicing junction part which joins bundles, the said fiber entanglement apparatus is the some linearly arranged on the 1st straight line which faces the width direction of the said fiber bundle. Fluid injection hole A first fluid ejection hole array and a second straight line parallel to the first straight line that is located at a distance in the longitudinal direction of the fiber bundle with respect to the first straight line. And a plurality of fluid ejection holes of the first fluid ejection hole array, and a plurality of fluid ejections of the second fluid ejection hole array. A plurality of fiber entangled portions in which the fibers positioned at intervals in the longitudinal direction of the fiber bundles are intertwined with each other in the fiber bundle overlapping portion by ejecting pressurized fluid from the holes And forming a fiber opening portion in a state where each of the fibers located between the plurality of fiber entangled portions is opened, and each of the fiber entangled portions is formed as the fiber bundle overlapping portion. The multiple fibers and the other fiber bundle of one fiber bundle in The plurality of fibers are entangled with each other, and formed so as to consist of a plurality of partial entanglements positioned at intervals in the width direction of the respective fiber bundles. The manufacturing method of the fiber bundle which has the thread splicing junction part joined.
The method for producing a fiber bundle according to claim 8, wherein each of the first fiber bundle and the second fiber bundle is a precursor fiber bundle for producing carbon fibers.
The method for producing a fiber bundle according to claim 9, wherein the connecting fiber bundle has a thermal conductivity of 3 to 700 W / m · K.
The method for producing a fiber bundle according to claim 10, wherein the connecting fiber bundle is a carbon fiber bundle, the drape value is 2 to 15 cm, and the flatness is 20 or more.
The method for producing a fiber bundle according to claim 11, wherein the fineness of the connecting fiber bundle is 0.2 to 3.0 times the fineness of the first fiber bundle and the second fiber bundle.
The method for producing a fiber bundle according to claim 11, wherein the tensile strength at normal temperature of the yarn splicing joint is 20 g / tex or more.
The distance between the first straight line and the second straight line is 20 to 100 mm, and the arrangement pitch of the fluid ejection holes in the first fluid ejection hole array and the second fluid ejection hole array is 1.7. The method for producing a fiber bundle according to claim 8, wherein the fiber bundle has a thickness of 4.5 mm.
A carbon fiber production method for producing carbon fibers by continuously passing the fiber bundle according to claim 4 through a flameproofing furnace and then a carbonization furnace.