JP2000088464A - Heat treatment furnace and manufacture of carbon fiber using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a temperature atmosphere in a heat treatment furnace uniform and to maintain the state for conducting a stable heat treatment by covering a periphery of a hot air diffusing nozzle with a heat insulator. SOLUTION: A hot air diffusing nozzle 32 is designed to cover a part surrounded by a shaded part with a heat insulator and to minimize a heat radiation Q1 from the nozzle 32 to an atmosphere V2 flowing from an exit/ entrance port 33 of a slit sealing structure. In a flame resisting furnace 31 for treating multi-filaments, a frontage of a filament exit/entrance port is lengthened, and the nozzle 32 indispensably lengthened in a lateral direction of the furnace, and hence its heat insulation characteristics are improved while suppressing its own weight deflection of the nozzle to a minimum limit by constituting it of a thin honeycomb member of a heat insulator part. Thus, a temperature difference in a heat treatment chamber can be made uniform, thereby assuring stability of its process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment furnace suitable for producing carbon fibers and a method for producing carbon fibers using the heat treatment.

[0002]

2. Description of the Related Art As a conventional heat treatment furnace, in particular, a heat treatment furnace used for producing carbon fibers, for example, as shown in FIG. There is known a heat treatment furnace 10 in which a device for circulating hot air for heat-treating a processing object 14 is incorporated.

The hot air circulating apparatus 10 includes a fan 18 for circulating hot air, a heater 17 for heating hot air,
The heat treatment chamber 11 includes a hot air blowing nozzle 12 for uniformly flowing hot air into the heat treatment chamber 11, a hot air suction nozzle 13, and a duct connecting them.

[0004] In such a heat treatment furnace, for example, when the furnace is a stabilization furnace, the stabilization treatment is performed by passing the yarn through a yarn path (yarn passage path) arranged in multiple stages in the heat treatment furnace. Is carried out, but polyacrylonitrile (P
In the case where an AN) -based precursor (precursor fiber) is subjected to a flame-resistant treatment, there are the following problems.

FIG. 2 is a cross-sectional view of one example of the structure of the hot air blowing nozzle viewed from directly above.
Numeral 2 extends into the heat treatment chamber from the side of the heat treatment furnace 21, and the hot air blowing nozzle 2 is provided at the entrance / exit 23 (the entrance / exit of the slit seal structure) of the workpiece on the side of the hot air blowing nozzle 22.
Due to the suction effect of the hot air (V1a to V1e) blown out from the outside air 2, room temperature outside air (V2) flows into the heat treatment chamber.

The inflowing outside air removes heat from hot air blowing nozzles provided above and below the passage of the workpiece, and flows into the heat treatment chamber (V2a to V2e).

At this time, a large amount of heat is taken from the nozzle 22 at the entrance / exit surface of the object.
The hot air (V1) supplied at a uniform temperature on the inlet side of the hot air blowing nozzle 22 itself generates a difference in temperature between the hot air (V1a to e) to be blown on the outlet side.
The 1a side is high and the V1e side is low.

For this reason, it is difficult to keep the atmospheric temperature in the heat treatment chamber uniform, and process troubles such as yarn breakage due to excessive product storage and heat quality of the processed object and variation in product quality and quality of the processed object are liable to occur. The problem occurs.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment furnace capable of maintaining a uniform temperature atmosphere in a heat treatment furnace and maintaining a stable heat treatment state. An object of the present invention is to provide a heat treatment furnace suitable for production and a method for producing carbon fiber using the same.

[0010]

In order to solve the above-mentioned problems, a heat treatment furnace according to the present invention has an entrance / exit having a slit seal structure for taking in / out an object to be treated into / from a heat treatment chamber, and is provided for heat-treating the object to be treated. A device for circulating hot air is incorporated, and in a heat treatment furnace having a nozzle that blows hot air in a direction along a passage of a processing object in the vicinity of a processing object inlet / outlet in the heat processing chamber, a heat insulating material surrounds the hot air blowing nozzle. It is characterized by being covered.

This heat treatment furnace can be constituted as a so-called vertical furnace, but is preferably a horizontal heat treatment furnace for allowing an object to be processed to pass in a substantially horizontal direction. A plurality of hot air blowing nozzles and a plurality of hot air suction nozzles are provided.

Further, the heat treatment furnace of the present invention has an entrance and exit of a slit seal structure for taking in and out the object to be treated into and out of the heat treatment chamber, and incorporates a device for circulating hot air for heat treating the object to be treated. In a heat treatment furnace having a nozzle that blows hot air in a direction along a passage of a processing object in the vicinity of a processing object inlet / outlet in a room, the hot air blowing nozzle has a temperature control function of controlling a blowing temperature. Become. In other words, as a measure against heat radiation from the nozzle, a heating means such as a sheathed heater and a sensor for temperature control are provided inside the nozzle with a large amount of heat radiation to supply the deprived heat amount. The effect can be obtained.

[0013] The method for producing carbon fibers according to the present invention comprises a method characterized by using a heat treatment furnace as described above and controlling the temperature of hot air blown from a hot air blow-off nozzle provided in the heat treatment furnace. .

In particular, the temperature of the hot air blown from the hot-air blowing nozzle has a temperature difference of 10 ° C. in the width direction of the nozzle.
It is better to control the temperature within 5 ° C., preferably within 5 ° C.

[0015] Such a heat treatment furnace is suitable for use in the production of carbon fiber, and converts the object to be processed into a thread to be used in the production of carbon fiber, that is, a precursor to be subjected to oxidizing treatment. It can be a body fiber or an oxidized yarn to be subjected to a carbonization treatment. That is, the heat treatment furnace can be used as an oxidation furnace, a carbonization furnace, or a drier after applying a process oil in the production of carbon fiber, and is particularly suitable as an oxidation furnace.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a simplified flame proofing furnace when a heat treatment furnace is used as a flame proofing furnace. In FIG. 1, reference numeral 10 denotes an entire oxidizing furnace having a heat treatment chamber 11, and the oxidizing furnace 10 is configured as a horizontal heat treatment furnace that passes a yarn 14 a plurality of times in a substantially horizontal direction. A plurality of hot-air blowing nozzles 12 and a hot-air suction nozzle 13 are provided in the flame-proof furnace 10.

The running direction of the yarn 14 fed from the inlet side into the oxidizing furnace 10 is reversed by the guide rollers 15, and passes through the entrances and exits 16 of the slit seal structure provided on both sides of the heat treating furnace 10, and is oxidized. It is supplied into the heat treatment chamber 11 of the furnace 10.

Hot air is circulated in the flameproofing furnace 10 through a hot air blowing nozzle 12 and a hot air suction nozzle 13, and a hot air circulation duct is connected to the nozzles 12 and 13. Hot air circulation fan 1
8, a heating heater 17 is provided,
Inside, hot air can be supplied while controlling the temperature.

FIG. 2 is a cross-sectional view of the flameproofing furnace shown in FIG. 1 as viewed from above, and shows a configuration around the hot air blowing nozzle 12. Reference numeral 21 denotes an outer wall of the oxidation furnace, and reference numeral 22 denotes hot air blowing nozzles arranged above and below the yarn (that is, a cross section of each nozzle 12 in FIG. 1 is shown). The yarn is supplied into the flameproofing furnace 21 through an entrance 23 having a slit seal structure.

The width H1 of the slit seal at the entrance 23 is a width H2 in which a plurality of yarns are arranged side by side so that multiple yarns can pass at one time.
There is a frontage larger than that.

Circulating hot air V1 heated to a uniform temperature
Is applied with an appropriate pressure loss by a punching plate or a mesh provided on the inlet / outlet side of the hot-air blowing nozzle 22 itself, so that a uniform air volume is blown out in the hot-air blowing nozzle 21 in the width direction of the hot-air blowing nozzle. ing.

The average temperature of the processing chamber in the oxidizing furnace 21 is determined as follows by the sum of the outside air V2 flowing from the entrance 23 of the slit seal structure and the circulating hot air V1. Processing chamber temperature = (V1 temperature x V1 mass + V2 temperature x V2
Mass) / (V1 mass + V2 mass)

When viewed locally, the temperature of each part in the processing chamber is determined as follows. (When the width direction of the heat treatment chamber is divided into five parts, the a, b, c, d, and e parts are taken from the upper side of the figure and correspond to the V1a to V1e parts in FIG. 2). V1a temperature x V1a mass + V2a
Temperature × V2a mass) / (V1a mass + V2a mass) The parts b, c, d, and e are also determined as described above in the same manner as the part a.

FIG. 3 is a detailed view of the vicinity of a hot-air blowing nozzle when the present invention is applied to the oxidation furnace shown in FIG.
Reference numeral 31 denotes an outer wall of the flameproofing furnace, and reference numeral 32 denotes hot air blowing nozzles disposed above and below the yarn. The yarn 34 is supplied into the oxidizing furnace 31 through an entrance 33 having a slit seal structure.

The hot air blow-out nozzle 32 has a portion surrounded by a hatched portion covered with a heat insulating material 35. The hot air blow-out nozzle 32 has a slit 3
3 is designed to minimize the heat radiation Q1 to the outside air V2 flowing in from outside.

The type of heat insulating material used here is as follows.
For example, there are rock wool, glass wool, asbestos, calcium silicate and the like, but glass wool is excellent in consideration of thermal conductivity.

The above-mentioned heat insulating material is surrounded by a thin plate of stainless steel, for example, and is not directly exposed to the furnace atmosphere.

Further, in the flameproofing furnace 31 for performing the multi-filament treatment, the frontage of the yarn inlet / outlet becomes longer, and the hot air blowing nozzle 32 naturally becomes longer in the width direction of the furnace. In such a case, the deflection of the hot-air blowing nozzle 32 under its own weight becomes large, and it becomes difficult to secure a sufficient yarn passing path. Therefore, in a flameproofing furnace that processes multiple yarns, the heat insulating material is not used as described above, and the heat insulating material portion is formed of a thin honeycomb member, while minimizing the deflection of the nozzle by its own weight, In addition, the heat insulation properties can be improved.

FIG. 4 is a cross-sectional view from the top when another embodiment of the present invention is applied to the stabilization furnace shown in FIG. 1 and shows details of a hot air blowing nozzle peripheral portion. It is a drawing of a heat treatment furnace having a function.

Reference numeral 41 denotes an outer wall of the oxidizing furnace, and reference numeral 42 denotes hot air blowing nozzles disposed above and below the yarn. The yarn is supplied into the flameproofing furnace 41 through the entrance / exit 43 of the slit seal structure.

A component 44 having a temperature adjusting function is disposed in the hot air blowing nozzle 42 in a flow path in which the amount of heat radiation is particularly large and the temperature of the hot air blowing nozzle 42 drops.

The component 44 having a temperature adjusting function is provided with heating means such as a sheathed heater and a heating medium pipe. Further, a sensor for detecting the temperature in the duct and controlling the heating means is provided at an appropriate position downstream of the heating means.

FIG. 4 shows only one heating means. However, when a more uniform furnace temperature is required, components 44 having a temperature control function are provided in all the flow paths in the hot air blowing nozzle 42. May be provided.

The component 44 having a temperature adjusting function provided in the hot air blowing nozzle 42 may be divided into a plurality of parts in the flow path of the nozzle, and the temperature control in this case is provided downstream of the nozzle. You may collectively manage the sensors.

In the flameproofing furnace having the above-described structure, the temperature of the hot air blown from the hot air blowing nozzle provided in the heat treatment furnace is controlled by the temperature difference in the width direction of the nozzle, that is, the width direction of the yarn to be processed. It is better to control the temperature within 10 ° C, preferably within 5 ° C.

In order to control the atmosphere in the processing chamber within a target temperature range, the above-described means for covering the hot air blowing nozzle with a heat insulating material and a control means using a temperature adjusting function are provided in combination. Is also good.

[0037]

Example 1 A PAN-based precursor (single yarn: 1 denier, number of filaments: 12,000 filaments) was fed at a running speed of 3 m / yarn.
Min, the average hot air circulation speed in the heat treatment room is 3 m / sec, the average temperature in the heat treatment room is 250 ° C, and the width of the slit seal section is 2
A horizontal flame stabilization furnace in which a hot air blowing nozzle of 000 mm was covered with a glass wool heat insulating material was subjected to a flame-proof treatment.

1 m from the outlet of the hot air blowing nozzle
Five thermocouples were arranged at a distance in the width direction of the heat treatment chamber, and the temperature in the furnace was measured. As a result, point A: 254 ° C, B
Point: 252 ° C, Point C: 248 ° C, Point D: 249 ° C, E
Point: 246 ° C., and the temperature difference was 8 ° C.

The number of fluffs generated in the obtained flame-resistant yarn is A
Point: 4.0 / m, Point B: 3.0 / m, Point C: 2.5
Pieces / m, D point: 2.5 pieces / m, E point: 2.0 pieces / m,
The average value is 2.8 yarns / m.
The carbonization yield of carbon fibers obtained by carbonization at 00 ° C is 5
The strength was 450 kgf / mm ² at 5%.

Example 2 A PAN-based precursor (single yarn: 1 denier, number of filaments: 12,000) was fed at a running speed of 3 m / y.
Min, the average hot air circulation speed in the heat treatment room is 3 m / sec, the average temperature in the heat treatment room is 250 ° C, and the width of the slit seal section is 2
A horizontal flame stabilization furnace in which a sheathed heater and a temperature sensor for control were disposed in a hot air blowing nozzle having a diameter of 000 mm was subjected to flameproofing treatment.

1 m from the outlet of the hot air blowing nozzle
Five thermocouples were arranged in the width direction of the heat treatment room at distant points, and the temperature in the furnace was measured. As a result, point A: 255 ° C, B
Point: 250 ° C, Point C: 247 ° C, Point D: 250 ° C, E
Point: 248 ° C., and the temperature difference was 8 ° C.

The number of fluffs generated in the obtained flame-resistant yarn is A
Point: 4.0 / m, Point B: 3.0 / m, Point C: 2.0
Pieces / m, D point: 2.5 pieces / m, E point: 2.0 pieces / m,
The average is 2.7 yarns / m, and this flame-resistant yarn is
Carbonization yield of carbon fiber obtained by carbonization at 00 ° C is 5
The strength was 446 kgf / mm ² at 4%.

Comparative Example 1 A PAN-based precursor (single yarn: 1 denier, number of filaments: 12,000) was fed at a running speed of 3 m / y.
Min, the average hot air circulation speed in the heat treatment room is 3 m / min, the average temperature in the heat treatment room is 250 ° C, and the width of the slit seal section is 2
000 mm, a hot-air blowing nozzle was subjected to a flame-proof treatment using a horizontal flame-proof furnace in which nothing was added.

1 m from the outlet of the hot air blowing nozzle
Five thermocouples were arranged at a distance in the width direction of the heat treatment chamber, and the temperature in the furnace was measured.
Point: 252 ° C, Point C: 249 ° C, Point D: 247 ° C, E
Point: 236 ° C., temperature difference was 29 ° C.

The number of fluffs generated in the obtained oxidized yarn is B
Point: 3.5 pieces / m, Point C: 2.0 pieces / m, Point D: 2.0
Pcs / m, E point: 1.5 pcs / m, average 2.3 pcs / m, carbonization yield of carbon fiber obtained by carbonizing this oxidized yarn at 1400 ° C in nitrogen 402 kg strength at 55%
f / mm ² . However, the yarn which was to be heat-treated around the point A where the temperature in the processing chamber was high had many fluffs and was wrapped around a roll outside the furnace on the delivery side, and thus it was not possible to obtain a flame-resistant yarn.

As described above, by making the temperature unevenness in the width direction of the heat treatment chamber uniform, the processed material can be uniformly processed over the entire width of the heat treatment chamber, and the roll is not wrapped due to the generation of fluff and the like. Can be treated for flame resistance.

Examples 3-4, Comparative Examples 2-5 1 m away from the outlet of the hot air blow-off nozzle using a horizontal flame stabilization furnace in which a plurality of sheathed heaters and control temperature sensors are provided in the hot air blow-out nozzle. At the point, five thermocouples were arranged in the width direction of the heat treatment room, and the test was performed by changing the temperature difference in the furnace (set temperature difference 30 ° C, 25 ° C,
20 ° C, 15 ° C, 10 ° C, 5 ° C, 6 levels).

As the fixing conditions, a PAN precursor (single yarn: 1 denier, filament number: 12,000)
Book), the number of yarns to be processed is 20, the running speed of the yarn is 2 m / min,
The average hot air circulation speed in the heat treatment chamber is 3 m / sec, the average temperature in the heat treatment chamber is 245 ° C, and the width of the slit seal section is 200
0 mm. Further, the carbonization furnace in the post-process was processed at 1400 ° C. in a nitrogen atmosphere.

As evaluation parameters, the number of fluffs of carbon fiber per meter (average of 20 samples) The number of yarn breaks in an oxidizing furnace after a treatment time of 10 hours In the post-process (carbonization furnace) after a treatment time of 10 hours The number of thread breaks

As a result, as shown in Table 1, the temperature difference was 10 to 1
It was found that there was a difference in the number of yarn breaks between 5 ° C. In addition, the number of fluffs, which is a precursor of yarn breakage, also increases as the set temperature difference spreads, and the yarn damage due to excessive flame-proofing treatment increases at the point A, where the temperature becomes higher. Thread cutting is increasing in the post-process. Therefore, it can be seen that by making the temperature difference in the heat treatment furnace 10 ° C. or less, more preferably 5 ° C. or less, the production equipment becomes practically excellent.

[0051]

[Table 1]

[0052]

As described above, according to the heat treatment furnace and the carbon fiber manufacturing method of the present invention, the temperature difference in the heat treatment chamber can be made uniform by covering the periphery of the hot air blowing nozzle with the heat insulating material. As a result, the stability of the process is ensured and the quality of the product is improved.

The same effect can be obtained by providing a temperature adjusting means in the hot air blowing nozzle.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a heat treatment furnace according to an embodiment of the present invention, as well as a general heat treatment furnace.

FIG. 2 is a partial schematic configuration diagram of a heat treatment furnace according to an embodiment of the present invention, in addition to a general heat treatment furnace.

FIG. 3 is a partial schematic configuration diagram of a heat treatment furnace according to an embodiment of the present invention.

FIG. 4 is a partial schematic configuration diagram of a heat treatment furnace according to an embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 heat treatment furnace (flame-resistance furnace) 11 heat treatment chamber 12 hot-air blowing nozzle 13 hot-air suction nozzle 14 thread 15 guide roller 16 entrance of slit seal structure 17 heater for heating 18 fan for hot-air circulation 21 heat treatment furnace (flame-proof furnace) 22 hot air Blowing nozzle 23 Entrance and exit of slit seal structure H1 Slit seal width H2 Yarn processing width V1 Circulating hot air V1a, V1b, V1c, V1d, V1e Circulating hot air viewed locally V2 Outside air V2a, V2b, V2c, V2d, V2e Inside the heat treatment furnace Inflowing outside air 31 Heat treatment furnace (oxidizing furnace) 32 Hot air blowing nozzle 33 Entrance and exit of slit seal structure 34 Thread 35 Heat insulating material Q1 Radiation 41 Heat treatment furnace (oxidizing furnace) 42 Hot air blowing nozzle 43 Entrance and exit of slit seal structure 44 Temperature control Functional parts

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideyuki Arakane 1-1-1, Sonoyama, Otsu-shi, Shiga F-term in the Shiga Plant of Toray Industries (reference) 3K058 AA86 BA00 4K050 AA02 BA09 CA11 CD17 CF01 CF11 CG01 4L037 CS03 CT10 CT12 CT14 CT42 FA03 FA07 PA53 PC05 PS02 PS20

Claims (8)

[Claims] 1. An inlet / outlet having a slit seal structure for taking in / out an object to be processed into / out of a heat treatment chamber, and a device for circulating hot air for heat treating the object to be processed is incorporated. A heat treatment furnace having a nozzle for blowing hot air in a direction along a passage path of an object to be processed, wherein a periphery of the hot air blowing nozzle is covered with a heat insulating material. 2. The horizontal heat treatment furnace, wherein the heat treatment furnace is a horizontal heat treatment furnace for passing the yarn in a substantially horizontal direction.
The heat treatment furnace according to claim 1, wherein the plurality of hot air blowing nozzles are arranged above and below the yarn. 3. The heat treatment furnace for carbon fibers according to claim 1, wherein the heat treatment furnace is a stabilization furnace used for carbon fiber production. 4. An apparatus having an entrance and exit of a slit seal structure for taking in and out an object to be processed into and out of the heat treatment chamber, and incorporating a device for circulating hot air for heat treating the object to be processed, in the vicinity of the entrance and exit of the object in the heat treatment chamber. A heat treatment furnace having a nozzle for blowing hot air in a direction along a passage of an object to be processed, wherein the hot air blowing nozzle has a temperature control function of controlling a blowing temperature. 5. The heat treatment furnace according to claim 1, wherein the heat treatment furnace is a horizontal heat treatment furnace that passes the yarn in a substantially horizontal direction.
The heat treatment furnace according to claim 4, wherein the plurality of hot air blowing nozzles are disposed above and below the yarn. 6. The heat treatment furnace for carbon fibers according to claim 4, wherein the heat treatment furnace is a stabilization furnace used for carbon fiber production. 7. A method for producing carbon fiber, comprising using the heat treatment furnace according to any one of claims 1 to 6 to control the temperature of hot air blown from a hot air blowing nozzle provided in the heat treatment furnace. . 8. The method for producing carbon fibers according to claim 7, wherein the temperature of the hot air blown from the hot air blowing nozzle is controlled within a temperature difference of 10 ° C. in the width direction of the nozzle.