JP3991784B2 - Heat treatment furnace and flameproofing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment furnace and a flameproofing method for heat treating yarns, and more specifically, heat treatment capable of ensuring a sealing function of the heat treatment furnace and producing carbon fibers having excellent productivity. The present invention relates to a furnace and a flameproofing method.
[0002]
[Prior art]
In general, as an apparatus for making a polyacrylonitrile-based precursor fiber flame resistant, as shown in Japanese Patent Application Laid-Open No. 2001-194071, a seal chamber is provided before and after the heat treatment furnace so that the temperature distribution in the heat treatment furnace is uniform. There have been proposals for a heat treatment furnace and a heat treatment method for improving heat efficiency and using heat energy efficiently.
[0003]
In order to stabilize the quality of an object to be processed obtained from a heat treatment furnace that makes such a polyacrylonitrile-based precursor fiber flame resistant, it is indispensable to keep the treatment chamber of the heat treatment apparatus constant at a predetermined temperature. . For this reason, for example, in a heat treatment furnace that continuously treats the precursor, a circulation path is provided inside and outside the heat treatment apparatus, and the process gas is circulated and used while being heated by a heater, so that the heat outflow from the heat treatment apparatus is reduced. By reducing as much as possible, the controllability of the temperature in the heat treatment furnace is improved and the temperature is kept constant.
[0004]
Here, in the heat treatment furnace, an inlet portion and an outlet portion of a precursor for continuously introducing and deriving the precursor are required. Generally, the inlet portion and the outlet portion are formed of a sheet-like precursor. In many cases, it is opened in a slit shape so as to enable introduction and extraction. The opening size of the slit is naturally set to be larger than the overall sheet-like cross-sectional shape of the precursor so that the introduction and derivation of the sheet-like precursor can be performed without difficulty. In this case, a gap is formed, and the generated gas leaks from the inside of the heat treatment furnace and the room temperature air leaks from the outside of the furnace.
[0005]
For example, in the method of making flame resistant in the above heat treatment furnace, heating and oxidizing the acrylonitrile-based synthetic fiber generates harmful components such as cyanide, ammonia and carbon monoxide. If the gas leaks out of the heat treatment furnace, it will adversely affect the working environment around the heat treatment furnace. In addition, leakage of room temperature air from the outside of the furnace causes a non-uniform temperature distribution in the heat treatment furnace, resulting in a deterioration in the quality of some precursors.
[0006]
In the heat treatment furnace, when the treatment object is made flame-resistant in a heat treatment furnace having a uniform temperature controllability by providing a sealing chamber by making the passage port of the object to be processed into a slit, it is generated in the heat treatment furnace. In order to minimize the leakage of gas out of the heat treatment furnace and the entry of room temperature air from the outside of the furnace, it is necessary to narrow the slit width. However, in order to continue production, when producing yarns with different numbers of filaments, the precursors are tied together or entangled with air to replace them. Therefore, it is necessary to make the width of the slit wider than in the normal production state in which the precursor is substantially sheet-like. Further, when the total number of filaments of the precursor is increased, the knot portion and the entangled portion are increased, so that it is necessary to increase the width of the slit more. Considering workability, the slit can be adjusted up and down, and even if it is adjusted using bolts or thumbscrews, it is difficult to adjust multi-stage slits in the height direction. Further, when a plurality of slits are provided in the yarn traveling direction in order to improve the sealing performance, the number of adjustment points is further increased and adjustment is difficult.
[0007]
[Problems to be solved by the invention]
In view of the problems of the prior art, the present invention is intended to provide a heat treatment furnace and a flameproofing method capable of producing carbon fibers that can be easily and stably produced and are excellent in productivity. is there.
[0008]
[Means for Solving the Problems]
The present invention employs the following means in order to solve such problems. That is,
(1) A heat treatment furnace for heat treating a yarn by circulating a heat treatment gas in a heat treatment chamber having an entrance portion and an exit portion of a running yarn, and at the openings of the entrance portion and the exit portion of the heat treatment furnace, A heat treatment furnace comprising a slit interval adjusting member having an opening / closing function capable of changing a slit interval, which is opened and closed by a rotation mechanism centering on an axis .
[0010]
( 2 ) The heat treatment furnace according to (1 ), wherein a plurality of the slit interval adjusting members are arranged in the yarn traveling direction, and the plurality of the slit interval adjusting members can be simultaneously opened and closed in conjunction with each other.
[0011]
( 3 ) By opening and closing the slit interval adjusting member, the opening area of the slit can be adjusted to 5 to 50% with respect to the cross-sectional area of the cross section perpendicular to the yarn traveling direction. The heat treatment furnace as described in said (1) or (2) .
[0012]
( 4 ) A flameproofing method using the heat treatment furnace according to any one of (1) to (3) .
[0013]
( 5 ) The flameproofing method as described in ( 4 ) above, wherein a polyacrylonitrile-based precursor is introduced.
[0014]
( 6 ) The flameproofing method as described in ( 5 ) above, wherein the total number of filaments of the polyacrylonitrile-based precursor is 10,000 or more.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention has been intensively studied on the above-mentioned problem, that is, a method for producing a carbon fiber that is improved in sealing performance, is stable, and has excellent productivity. It was clarified to solve the problem.
[0016]
In other words, a device that can open and close the slit and use the opening size properly according to the application, and using the device to make it flame resistant reduces the temperature spots in the heat treatment furnace due to the inflow of outside air, and stable quality carbon The fiber could be made.
[0017]
Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings.
[0018]
FIG. 1 is a schematic configuration diagram showing an example of a heat treatment furnace according to the present invention, and shows a closed state of a slit opening / closing mechanism. FIG. 2 is a schematic configuration diagram illustrating an example of a heat treatment furnace according to the present invention, and is a diagram illustrating an open state of the slit opening / closing mechanism in FIG. 1.
[0019]
FIG. 3 is a schematic configuration diagram showing another example of the heat treatment furnace according to the present invention, and shows a closed state of the slit opening / closing mechanism. FIG. 4 is a schematic configuration diagram illustrating another example of the heat treatment furnace according to the present invention, and is a diagram illustrating an open state of the slit opening / closing mechanism in FIG. 3.
[0020]
In this invention, it has the entrance part 10 and exit part 11 of the running yarn which is the to-be-processed object 7, and passes heat processing gas in the heat processing chamber 2 from the blower outlet 3 of heat processing gas as the arrow of a figure. The gas in the heat treatment furnace is discharged from the gas inlet 4 while blowing the gas to the object 7 that runs meandering in the heat treatment chamber by the rollers 5a and 5b, and the discharged gas is further blown out. 3 is a heat treatment furnace 1 that continuously heats the yarn, and is provided with a slit interval adjusting member 6 having an opening / closing function at the opening of the heat treatment chamber 2 and / or the opening of the outlet, The opening size of the slit is changed by opening and closing the slit interval adjusting member 6.
[0021]
In the present invention, the slit interval adjusting member is basically provided outside the heat treatment furnace 1 and is disposed above and below the workpiece 7.
In the present invention, it is necessary that the slit interval adjusting member has a mechanism that pivotally supports the slit interval adjusting member and opens and closes by rotating about the axis. Since it is preferable to widen the opening size when the slit is opened, a structure in which the slit can be varied in a range of 0 to 90 ° by rotating the shaft around the shaft is preferable.
[0022]
For example, when the shaft is provided at the center of the slit interval adjusting member, the slit can be opened at an interval excluding the thickness of the slit at the maximum when the shaft is rotated. As shown in FIG. 5, a shaft 8 is provided at the center of the slit interval adjusting member 6, and by rotating the shaft 8, the slit interval adjusting member interval adjusting member 6 can be opened in parallel as shown in FIG. 6. In addition, as shown in FIG. 7, when the shaft 8 is provided at the end of the slit interval adjusting member 6, the slit interval adjusting member 6 can be opened in parallel as shown in FIG. .
[0023]
In the present invention, it is preferable that two or more slit interval adjusting members 6 are arranged in the traveling direction of the workpiece. In order to prevent the in-furnace heat treatment gas from leaking out of the heat treatment furnace or flowing out of the outside air into the furnace, it is desirable that a plurality of the slit interval adjusting members 6 be arranged in the workpiece traveling direction. It is also effective to obtain the sealing property by circulating the heated outside air between the plurality of slit interval adjusting members in order to obtain a better sealing property. It is preferable that a plurality of slit interval adjusting members are interlocked to open and close the plurality of slit interval adjusting members simultaneously.
[0024]
As a method for simultaneously opening and closing a plurality of slit interval adjusting members, for example, as shown in FIGS. 9 and 11, the slit interval adjusting member 6 is provided with a link mechanism 9, and the respective shafts are rotated by a cylinder or the like. It can be interlocked as shown in FIG.
[0025]
Moreover, in this invention, the opening area of a cross section perpendicular | vertical with respect to a yarn advancing direction can be freely adjusted by opening and closing the said slit space | interval adjustment member. The slit spacing adjusting member is preferably narrow during normal production, and is preferably as wide as possible during production preparation such as changing other precursors and cleaning the heat treatment furnace. Therefore, during normal production, the slit is preferably about 5 to 10% with respect to the cross-sectional area of the cross section perpendicular to the yarn traveling direction, and in other cases, about 30 to 50% is preferable. More preferably, it is possible to obtain a free opening size in a range of 5 to 50% by fixing in the middle of opening and closing.
[0026]
Further, the present invention is characterized in that a polyacrylonitrile-based precursor is introduced into the horizontal heat treatment furnace. In producing the carbon fiber, there is a flameproofing process in which the precursor fiber is heat-treated from 200 ° C. to 300 ° C. in an oxidizing atmosphere. When performing such treatment, in order to stabilize the quality, it is important to keep the temperature in the heat treatment furnace constant and uniform in the width direction of the heat treatment furnace. For this reason, in the heat treatment furnace for continuously treating the object to be treated, the heat outflow amount from the heat treatment apparatus is reduced as much as possible, and the inflow amount of the outside air into the heat treatment furnace is reduced. The temperature controllability is improved to keep the temperature uniform.
[0027]
Here, the heat treatment furnace is provided with an opening for continuously taking in and out the object to be processed. Generally, the opening for taking in and out the object to be processed has a slit structure, and a gap with the object to be processed as much as possible. Is to reduce. For continuous production, the precursors are tied together or entangled with air, such as when producing yarns with different numbers of filaments or when the workpiece is periodically replaced. Since the yarn bundle is thick and is caught between the slit interval adjusting member and the slit interval adjusting member, the entangled portion is often opened more than in order to introduce and lead out the sheet-like workpiece. In order to minimize the gap with the slit interval adjusting member, the gap between the slit interval adjusting member and the object to be processed can be narrowed by closing the open / close slit.
[0028]
In the present invention, it is preferable that the total number of filaments of the polyacrylonitrile-based precursor processed in the heat treatment furnace is 10,000 or more. More preferably, it is the range of 30,000-100,000.
[0029]
When the total number of filaments in the precursor increases, after the regular repairs and cleaning of the heat treatment furnace, if the precursor is replaced in the heat treatment furnace by tying and entanglement, the knots and entanglement will become larger and more slits will be formed. It is necessary to take a wide width. In that case, the gap between the slit and the object to be processed needs to be widened, and the gap between the slit and the object to be processed can be widened by opening the open / close slit.
[0030]
【Example】
Examples of the present invention and comparative examples will be specifically described below.
[0031]
Example 1
The width of the slit interval adjusting member 6 is adjusted to 1000 mm, the height is adjusted to 100 mm when opened, and 5 mm when fully closed, the distance between the paths is 250 mm, and two slit interval adjusting members are installed in the precursor running direction, A horizontal heat treatment furnace 1 for blowing a heat treatment gas from a direction perpendicular to the precursor running direction was used. The slit interval adjusting member 6 was rotated by rotating the slit rotating shaft 8 to replace the object to be processed in the open state, and the slit interval adjusting member 6 was closed by rotating the slit rotating shaft 8 so that the width of the slit was 5 mm. The temperature of the heat treatment furnace 2 was set to 250 ° C., and the object to be processed was run. Since the slit interval adjusting member and the object to be processed are in contact with each other while the workpiece is running, the slit interval adjusting member is opened, and the angle of the slit interval adjusting member is adjusted so that the gap with the object to be processed is 10 mm.
[0032]
Under these conditions, the polyacrylonitrile precursor was flameproofed at a heat treatment furnace temperature of 250 ° C. As a result, the temperature inside the heat treatment furnace became uniform, and the heat treatment gas leaked from the heat treatment furnace and the outside air did not flow from the outside of the heat treatment furnace, and the carbon fiber precursor could be made flame resistant stably.
[0033]
【The invention's effect】
According to the present invention, it is particularly suitable for a heat treatment furnace for making a polyacrylonitrile-based precursor fiber bundle having a total number of filaments of 10,000 or more to be flame resistant and a flameproofing method thereof, and to be processed by an open / close type slit interval adjusting member. By adjusting the gap between the slit spacing adjusting member to, for example, 5% to 50%, the gap with the slit during continuous operation is adjusted, the temperature in the heat treatment furnace is kept constant, and uniform in the width direction of the heat treatment furnace And, after repairs and cleaning of the heat treatment furnace that are regularly performed, and when replacing the precursor in the heat treatment furnace by tying and entanglement, the gap between the slit interval adjusting member and the object to be processed is widened. Satisfaction improves the productivity by suppressing quality irregularities and workability in the flameproofing process, and stably, smoothly and quickly flameproofing and passing the process stably. Suitable heat treatment furnace and flame method to a carbon fiber production method can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a heat treatment furnace according to the present invention (slit opening / closing mechanism closed state).
FIG. 2 is a schematic configuration diagram showing an example of a heat treatment furnace according to the present invention (a state in which a slit opening / closing mechanism is opened).
FIG. 3 is a schematic configuration diagram showing another example of the heat treatment furnace according to the present invention (slit opening / closing mechanism closed state).
FIG. 4 is a schematic configuration diagram showing another example of the heat treatment furnace according to the present invention (in a state where the slit opening / closing mechanism is opened).
FIG. 5 is a partially enlarged sectional view showing an example of a closed state of the slit opening / closing mechanism of the heat treatment furnace according to the present invention.
FIG. 6 is a partially enlarged sectional view showing an example of an open state of a slit opening / closing mechanism of the heat treatment furnace according to the present invention.
FIG. 7 is a partially enlarged sectional view showing another example of the closed state of the slit opening / closing mechanism of the heat treatment furnace of the present invention.
FIG. 8 is a partially enlarged cross-sectional view showing another example of the open state of the slit opening / closing mechanism of the heat treatment furnace of the present invention.
FIG. 9 is a partially enlarged cross-sectional view showing an example of a closed state of a plurality of slit opening / closing methods in the processing object traveling direction of the heat treatment furnace according to the present invention.
FIG. 10 is a partially enlarged cross-sectional view showing an example of an open state of a plurality of slit opening / closing methods in the processing object traveling direction of the heat treatment furnace according to the present invention.
FIG. 11 is a partially enlarged cross-sectional view showing another example of the closed state of the plurality of slit opening / closing methods in the processing object traveling direction of the heat treatment furnace according to the present invention.
FIG. 12 is a partial enlarged cross-sectional view showing another example of the open state of the plurality of slit opening / closing methods in the direction of the workpiece in the heat treatment furnace according to the present invention.
[Explanation of symbols]
1: Heat treatment furnace 2: Heat treatment chamber 3: Heat treatment gas blowout port 4: Gas inlet 5a, 5b in the heat treatment furnace: Roller 6: Slit interval adjusting member 7: Object to be treated (yarn)
8: Slit interval adjusting member rotating shaft 9: Link mechanism for interlocking with slit 10: Entrance portion of workpiece 11: Exit portion of workpiece

Claims (6)

A heat treatment furnace for heat treating a yarn by circulating a heat treatment gas in a heat treatment chamber having an entrance portion and an exit portion of a running yarn, wherein the shaft is centered at the opening portions of the entrance portion and the exit portion of the heat treatment furnace. A heat treatment furnace characterized in that a slit interval adjusting member having an opening / closing function capable of changing the slit interval is arranged to be opened and closed by a rotating mechanism . 2. The heat treatment furnace according to claim 1, wherein a plurality of the slit interval adjusting members are arranged in the yarn traveling direction, and the plurality of the slit interval adjusting members can be simultaneously opened and closed in conjunction with each other. 2. The slit spacing adjusting member is opened and closed so that the opening area of the slit can be adjusted to 5 to 50% with respect to the cross-sectional area of the cross section perpendicular to the yarn traveling direction. Or the heat treatment furnace of 2 . A flameproofing method using the heat treatment furnace according to any one of claims 1 to 3 . The flameproofing method according to claim 4 , wherein a polyacrylonitrile-based precursor is introduced. The flameproofing method according to claim 5 , wherein the total number of filaments of the polyacrylonitrile-based precursor is 10,000 or more.

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