JPH11200159A - Production of carbon fiber and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a carbon fiber in baking plural small tows obtained by dividing a precausor fiber bundle in width direction, capable of continuously obtain the desired carbon fiber by simply and stably exchanging the precausor fiber bundle. SOLUTION: This method for producing a carbon fiber is provided by traveling plural small tows having >=30,000 denier total fiber thickness continuously, joining each of the small tows with each of the plural small tows having >=30,000 denier total fiber thickness obtained by dividing another precausor fiber bundle in width direction and then baking. In the carbon fiber production device having the above joining process, the joining process has plural guiding rolls 3 and 5, and among them at least one guiding roll is constituted as a movable guiding roll capable of temporarily stopping the traveling of the precausor fiber bundle 2 positioned at the upstream side to the guide roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing carbon fiber and a production apparatus used for the method.

[0002]

2. Description of the Related Art Generally, the production speed of a precursor fiber bundle, which is a raw material for producing carbon fibers, is different from the production speed of carbon fibers in which the precursor fibers are fired. The transition process to the manufacturing process is not continuous. For this reason, the precursor fiber bundle is once wound around a bobbin or the like, or folded and accommodated in a box. Therefore, in order to continuously produce carbon fibers using the precursor fiber bundle, the end of the precursor fiber bundle supplied from the bobbin or the box is replaced with the next precursor contained in another bobbin or the box. It must be connected to the beginning of the fiber bundle.

[0003] Here, a group of a plurality of small tows having a predetermined number of filaments is formed, and after maintaining this state, the group of the plurality of small tows is formed into a single tow state. After being bundled into a form that can be divided into a plurality of small tows at the time of later use, the material wound on a bobbin or housed in a box is divided horizontally before firing and fired to produce carbon fiber. And sometimes.

[0004] In such a case, when the precursor fiber bundle being fired is switched to another precursor fiber bundle, the next precursor fiber bundle is replaced with a plurality of, for example, 30,000 or more filaments. After splitting laterally into small tows, it is necessary to connect each small tow of the precursor fiber bundle that is being fired.

[0005] However, when a plurality of small tows are connected one by one, twist is mixed into the yarn, and heat is stored in the yarn during firing in a subsequent flame-proofing step or the like, and the yarn is burned out, or the precursor is originally used. The places where the fiber bundles should be connected in the form of a sheet may be connected by inserting small tows, and the thread may be caught by the roller portion or the like. In addition, the displacement of the connecting part occurs between the yarns,
When the deviation accumulates, the yarns may become entangled with each other when the precursor fiber bundle is supplied, and supply may not be possible.

[0006] As a method of connecting the precursor fiber bundle,
It is common to connect the ends of each precursor fiber bundle by connecting them together, but in the knot formed by this connection, it is easy to store heat during firing, especially in the flameproofing step, and this heat storage phenomenon There is a high possibility that breakage or burnout will occur around the connection.

As a method for avoiding such a problem, there is a method in which the precursor fiber bundles or the precursor fiber bundles and the oxidized yarn are entangled with each other by a high-speed fluid treatment. In order to connect the running yarn in order to perform the operation with the yarn fixed, the yarn of a length considering the connection time is used so that the yarn at the connection portion can be substantially stopped during the connection. Need to be secured. Conventionally, the yarn of this length was secured by pulling it out onto a box while maintaining the precursor fiber bundle in a toe shape.However, in this method, when the tow is supplied, the yarns become entangled with each other, making it impossible to connect. There was something.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the above-mentioned problems, that is, to sinter a plurality of small tows obtained by dividing a precursor fiber bundle in a horizontal direction before sintering. It is an object of the present invention to provide a method of producing carbon fibers by which a precursor fiber bundle can be easily and stably switched in a method of obtaining carbon fibers, and a desired carbon fiber can be continuously obtained.

[0009]

Means for Solving the Problems In order to solve the above problems, a method for producing carbon fibers of the present invention comprises a plurality of fibers having a total fineness of 30,000 denier or more obtained by dividing a precursor fiber bundle in a lateral direction. Small tows continuously (eg, at a speed of 0.5
m / min or more), and each of the small tows is divided into a plurality of small fibers having a total fineness of 30,000 denier or more obtained by dividing a precursor fiber bundle different from the precursor fiber bundle in the lateral direction. After connecting to each of the tows, firing is performed.

In the method for producing carbon fibers according to the present invention, when connecting a plurality of small tows, the traveling path of the traveling small tow is changed using a movable guide roll during the time required for connection. It is preferable to substantially stop the small tow located on the upstream side of the type guide roll. This makes it possible to easily connect another small tow to be connected to the stopped small tow. Here, in order to prevent twist from being mixed into the small tow after connection, it is preferable that the precursor fiber bundle be run in a sheet shape. It is preferable that the connections between the small tows are made substantially simultaneously.

An apparatus for producing carbon fibers according to the present invention connects a precursor fiber bundle which can be divided into a plurality of small tows in a lateral direction and another precursor fiber bundle which can be divided into a plurality of small tows in a lateral direction. In the carbon fiber manufacturing apparatus having the step of performing, the connecting step has a plurality of guide rolls, at least one of the guide rolls, the traveling of the precursor fiber bundle located on the upstream side of the guide rolls The movable guide roll is configured to be able to temporarily stop.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with preferred embodiments. The precursor fiber bundle used for the production of carbon fiber is made of a polyacrylonitrile-based synthetic fiber tow that can be divided into small tows having a total fineness of 30,000 denier or more, and is wound around a bobbin or folded and laminated in a box. In a stored form, it is supplied to the firing step. When the precursor fiber bundle stored in the bobbin or the box body comes to the end, the starting end of the next prepared precursor fiber bundle is connected. That is, the end portions of the precursor fiber bundle are connected to each other. The connected precursor fiber bundle is continuously fired to continuously produce carbon fibers for a long time. According to the present invention, particularly in a method for producing a carbon fiber using a precursor fiber bundle having a large number of filaments, it is possible to easily and stably connect the precursor fiber bundles before the flame-proofing step.

In particular, a precursor fiber bundle having an ability to be divided into small tows having a number of filaments of 30,000 or more is targeted, and when a precursor fiber bundle continuously fed out from a bobbin or a box comes to the end, the next step. Is prepared, and the ends of the precursor fiber bundles are connected to each other. The tow is run and fired at a substantially constant speed, usually greater than 0.5 m / min.

FIG. 1 shows an apparatus configuration which enables a running tow-like precursor fiber bundle to be connected in a sheet form without being twisted while being fixed by a connecting means.

In FIG. 1, a precursor fiber bundle 2 housed in a box 1 is raised vertically, and the precursor fiber bundle is caused to travel between guide rolls 3, 4, and 5 arranged in zigzag. At this time, since the connection of the precursor fiber bundles is performed in units of small tows, it is preferable that the precursor fiber bundles 2 run in a sheet shape so that the small tow dividing operation can be easily performed.

To connect the ends of the precursor fiber bundle, the precursor fiber bundle is divided into a plurality of small tows, and the ends of the divided plurality of small tows are substantially simultaneously subjected to high-speed fluid treatment. Can be used. Here, the term "to connect the end portions of the small tows substantially simultaneously" means that the end portions of the plurality of small tows to be connected and the end portions of the plurality of small tows to be connected are aligned in the connection means, and one connection is made. Connecting by work. That is, as shown in FIG. 3, the order of the small tows to be connected is switched, such as the ends of the small tows 10a to be connected and the ends of the small tows 10b to be connected, and the ends of the small tows 11a and 11b to each other. Instead of forming a plurality of connecting tows at once (small toe connecting portion 12). In addition, to connect one by one means that one small tow to be connected and one end of one small tow to be connected are
This means that the connection is made at the connection means and the operation is repeated a plurality of times for a few tows.

It is preferable to apply a high-speed fluid treatment to the method of connecting the precursor fiber bundle, and steam, water, air or the like can be used as a jetting fluid. The air method is preferred. In this case, the structure of the nozzle from which air is injected is such that even a fiber bundle with a large number of filaments is opened at the single yarn level,
It is preferable to be able to entangle.

The guide roll 3 used in the above apparatus,
4 and 5 are preferably made of a material having a low contact resistance so that the precursor fiber bundle can easily travel in a sheet shape. The width (surface length) of the guide rolls 3, 4, 5 is longer than the width of the sheet-like precursor fiber bundle, and if necessary, a guide (for example, a brim guide or the like) that regulates the spread of the tow at the end of the roll. May be attached. Further, the guide roll 4 is configured as, for example, a movable roll having a structure movable in a horizontal direction so as to secure a relaxed length in consideration of a time required for connection, and the relaxed length is reduced during the connection work. A mechanism is provided that can move in the direction of movement. The movement of the movable roll 4 makes it possible to substantially stop the precursor fiber bundle located on the upstream side in the traveling direction of the movable guide roll 4 during the connection work, so that the connection work can be easily performed. it can.

As a means for securing the relaxed length of the precursor fiber bundle, it is preferable that the guide roll 4 is electrically driven, but it may be moved manually. It is also preferable that the guide roll 4 is moved and relaxed at a certain rate by an electric method, but the relaxation is naturally relaxed by the tension of the running precursor fiber bundle applied to the guide roll 4. May be.

As described above, in the carbon fiber manufacturing apparatus for connecting the precursor fiber bundle according to the present invention, the end portions of the precursor fiber bundle can be simultaneously connected without twisting, and the precursor fiber bundle is zigzag. By moving the movable guide roll 4 when connecting using the guide rolls arranged in a row, it is possible to fix the precursor fiber bundle located in the connection work section at a fixed position and easily perform the connection work. it can.

As described above, since the connection of the precursor fiber bundle is performed in units of small tows, the precursor fiber bundle is divided into a plurality of small tows at the time of relaxing relaxation, and the end portion is connected for each small tow. In addition, the movable guide roll 4 can ensure relaxation while holding the precursor fiber bundle 2 in a sheet shape, without causing a displacement of a connecting portion for each small tow.
In addition, it can be stably transported to the flameproofing process without twisting.

[0022]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Example 1 In order to confirm the effect of the present invention, a yarn joining operation was performed using the above-described guide roll. As shown in FIG. 2, the precursor fiber bundle stored in the box body is vertically raised, and after passing through a roll 7, is supplied to the oxidizing step (oxidizing furnace 9) at a constant speed by the drive station 8. Is done. The box containing the next precursor fiber bundle is placed next to the box containing the traveling precursor fiber bundle, and when the traveling precursor fiber bundle comes to the end, the next precursor fiber bundle is placed. It was connected to the beginning of the body fiber bundle.

The precursor fiber bundle had a single yarn fineness of 1.5 d, the number of filaments was 280,000, and the total denier was 420,00.
0 is a polyacrylonitrile fiber bundle. The fiber bundle is crimped in order to make the fiber bundle easily rise from the inside of the box and pass through the yarn path. At the start-up position, this precursor fiber bundle is divided into small tows having a filament number of 70,000 (total of four small tows), and the next precursor fiber bundle divided into small tows in advance is connected with the end portions. Connected. In connection work, relaxation was ensured using a manual guide roll. The guide rolls are located at a height of 2.5 m in the vertical direction from the box 1 in which the precursor fiber bundles are stored during running, and the three guide rolls 3 of the relaxation guide device 6 at the time of connection are provided. Only the center guide roll 4 out of 4 and 5 was moved in the horizontal direction to secure a long yarn path.

The running speed of the precursor fiber bundle was set at 1.2 m / min, and the relaxed length of the tow was set at 4 m in consideration of the yarn joining operation time. As a means for relaxing and relaxing, a mechanism in which the guide roll 4 moves by the tension of the running precursor fiber bundle applied to the roll is adopted.

As a result of the simultaneous connection of the precursor fiber bundles in small tow units in this manner, no displacement between the small tows at the connection portion occurred, and no twisting occurred between the small tows due to the connection.
In addition, as shown in Table 1, the yarn joining operation time was significantly reduced by using the guide roll.

Comparative Example 1 A precursor fiber bundle rising in a sheet shape was divided into small tows having a filament number of 70,000, and was previously divided into small tows having a filament number of 70,000. Then, the next precursor fiber bundle was connected to each end. To secure the relaxation in the connection work, a method by hand-handling was adopted without using a guide roll. The running speed and the relaxation length of the precursor fiber bundle were carried out under the same conditions as in Example 1, and the working time, the displacement of the connecting portion between the small tows, and the presence or absence of twist were evaluated. In this method, as shown in Table 1, workability was extremely poor, and deviation and twist between small tows occurred frequently.

[0027]

[Table 1]

[0028]

As described above, according to the present invention,
The following excellent effects can be obtained. (1) Total fineness 3 with the ability to divide into small tows
In connecting a precursor fiber bundle of 0000 denier or more, displacement and twisting of a connecting portion between small tows can be suppressed, and a plurality of small tows can be connected easily and stably simultaneously. (2) Since the precursor fiber bundle including the connection portion is continuously transported to the flame-proofing step, the workability of connecting the precursor fiber bundles or the productivity of carbon fibers is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a precursor fiber bundle rising section of a carbon fiber manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic side view showing a carbon fiber manufacturing apparatus according to one embodiment of the present invention.

FIG. 3 is a schematic view showing a connection state between precursor fiber bundles in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Box 2 Precursor fiber bundle 3, 5 Guide roll 4 Movable guide roll 6 Relax guide device 7 Roll 8 Drive station 9 Oxidation furnace 10a, 11a Small tow to be connected 10b, 11b Small tow to be connected 12 Small toe connection Department

Claims (5)

[Claims] 1. A plurality of small tows having a total fineness of 30,000 denier or more, which are obtained by dividing a precursor fiber bundle in a horizontal direction, are continuously run, and each of the small tows is mixed with the precursor fiber bundle. A method for producing carbon fibers, comprising connecting each of a plurality of small tows having a total fineness of 30,000 denier or more obtained by dividing a precursor fiber bundle different from the above in the horizontal direction, followed by firing. 2. The method for producing carbon fibers according to claim 1, wherein the small tow is run at a speed of 0.5 m / min or more. 3. When connecting the small tows, the yarn path of the running small tow is changed using a movable guide roll during the time required for the connection, and the small tow located upstream of the movable guide roll is substantially changed. 3. The method according to claim 1, further comprising:
The method for producing a carbon fiber according to the above. 4. The carbon according to claim 1, wherein each of the plurality of small tows and another plurality of small tows connected to each of the plurality of small tows are connected substantially simultaneously. Fiber manufacturing method. 5. A carbon fiber manufacturing apparatus comprising a step of connecting a precursor fiber bundle which can be divided into a plurality of small tows in a lateral direction and another precursor fiber bundle which can be divided into a plurality of small tows in a lateral direction. In the, in the connecting step, having a plurality of guide rolls,
At least one of the guide rolls is configured as a movable guide roll capable of temporarily stopping the traveling of the precursor fiber bundle located on the upstream side of the guide roll, Equipment for manufacturing carbon fiber.