JPH0571019A - Melt spinning of pitch - Google Patents

Abstract

PURPOSE:To produce a high-quality pitch fiber while improving spinning workability and environmental safety by supplying an air current in the opposite direction to the yarn-adjoint stream from a spinning cooling chamber and preventing vibration of yarns and diffusion of low-boiling substance vapor. CONSTITUTION:A petroleum-or coal-based pitch is initially melted and discharged through a nozzle 1 by the conventional method and subsequently cooled by a cooling unit 2 directly under the discharge plane of the nozzle 1. While supplying, during this process, an air current through an air-supply opening 5 into the spun yarn-cooling chamber 7 in the direction opposite to a yarn- adjoint stream generated from the spun yarn-cooling chamber 7 by friction between the spinning fiber (Y) bundle and the air, melt spinning of the pitch is carried out. Since it is preferable to discharge the air from the spun yarn- cooling chamber 7 in an amount larger than that of the yarn-adjoint stream, a yarn-drawing method by a suction gun 3, capable of discharging the air in the spun yarn-cooling chamber together with the yarn-adjoint stream is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pitch for producing a pitch fiber on an industrial scale from a fiber-forming pitch (hereinafter abbreviated as "pitch") made from petroleum or heavy coal-based oil. It relates to a melt spinning method.

[0002]

[Prior art and its problems] Currently, pitch fibers are used in the field of adsorbents such as solvents and malodorous substances as activated carbon fibers by inactivating after infusibilization, or by being carbonized to have high elastic and high strength fiber functions. It is widely used as a carbon fiber in the field of reinforcing materials.

Generally, in order to spin a pitch made from a petroleum-based or coal-based heavy oil as a raw material, it is necessary to spin the synthetic fiber at a higher temperature than when melt-spinning a normal synthetic fiber. Generally, the softening point of the pitch to be melt-spun is about 200 to 350 ° C., and the melting point of the pitch to be melt-spun is 30 ° C. from the softening point of the pitch to be spun.
As described above, the set temperature is preferably 40 ° C. or higher, and for example, when the softening point is 290 ° C., the spinning temperature is about 340 ° C. When spinning the pitch fibers, a method of spinning synthetic fibers has been conventionally used as it is.

However, in the method of spinning synthetic fibers, an air supply method is adopted as a cooling method during spinning. In such a method, air is blown out sideways, that is, air is supplied from a direction perpendicular to the yarn drawing direction. Therefore, thread sway easily occurs. In particular, when the number of discharge holes of the spinneret increases, a difference occurs in the amount of air supplied to the yarn wake at each discharge hole that occurs during spinning. It becomes more prominent as the number of ejection holes of the spinneret increases. In particular, pitch is more likely to cause a yarn wake flow than synthetic fibers, and has a high softening point, that is, it has the property of rapidly cooling and thinning (solidifying) when the temperature decreases even a little. Very easily affected,
Therefore, pitch single yarn breakage occurs due to yarn fluctuations in the high temperature range, or pitch adheres to the die surface and impedes continuous spinnability, and pitch fibers at the time of infusibilization due to mixing of single yarn cut fibers Combustion occurs, which significantly reduces the operability and makes it difficult to maintain stable spinnability for a long period of time.Furthermore, since the pitch is composed of an aromatic condensed polycyclic compound with a wide molecular weight distribution range, it melts. A large amount of low-boiling point substance vapor is generated during spinning, and the vapor flows into the peripheral device together with the yarn accompanying flow and adheres and accumulates. For this reason, it is necessary to replace each device, and when the yarn drawing is performed by the suction gun, it causes a change in the fiber diameter due to a change in the traction force of the suction gun and a variation in the basis weight of the sheet. Will be lowered. Further, since the vapor of the low boiling point substance itself deteriorates the working environment, it is necessary to pay close attention to the leakage of the above substance to the outside.

Therefore, at present, there is a strong demand for the development of a novel pitch melt spinning method in consideration of properties peculiar to pitch fibers, separately from the spinning method of synthetic fibers.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to produce high quality pitch fiber while improving spinning operability, environmental safety and the like.

As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems, that is, the adverse effects of yarn sway and vapors of low-boiling substances, as a result, the yarn entrainment caused by friction between the fiber yarn bundle during spinning and air. That the flow is the cause, and further that the air viscosity of the air that is the source of the accompanying flow and the turbulence of the air flow have a great influence on the speed change of the yarn bundle during spinning. Since it depends on the temperature, the degree of fluctuation of the yarn bundle changes due to the temperature of the air introduced into the spinning cooling chamber and the characteristics of the flow direction, and the thinning point of the single yarn changes. did. Based on such a viewpoint, by controlling the accompanying flow generated by friction between the fiber bundle and the air during spinning, specifically, the air flow is generated in the direction opposite to the yarn accompanying flow from the spinning cooling chamber. By supplying air uniformly to each wake of each discharge hole and reducing or preventing turbulence of each yarn wake, excellent spinnability is obtained and diffusion of low boiling point substances is prevented. The inventors have found out what can be done and have completed the present invention.

That is, the present invention is a method for melt spinning a pitch, characterized in that, when pitch fibers are produced from petroleum-based or coal-based pitch, an air flow is supplied in the direction opposite to the yarn accompanying flow from the spinning cooling chamber. It is related to.

The present invention will be described in detail below.

First, the pitch melt spinning method of the present invention will be outlined with reference to the drawings. FIG. 1 is a schematic view showing an example of a pitch fiber sheet manufacturing apparatus. The molten pitch (P) is taken up by a suction gun (3) while a cooling fluid is applied by a cooling device (2) immediately below the discharge of the nozzle mouthpiece (1) to form a yarn (Y). The spinning cooling chamber (7) is isolated from the outside air by the isolation wall (4), and the air supply port (5) provided around the suction gun (3) is connected to the flow rate adjusting valve (6). The yarn (Y) is sucked and pulled by the suction gun (3) together with the accompanying flow, and is arranged in a sheet shape by the traverse of the connecting portion (8) and the fiber-opening tube (9). Further, the pitch fiber sheet (S) can be obtained by a sheet forming apparatus having an induction duct (12) whose end is connected to a bag filter, a suction container part (11) and a sheet holding wire mesh (10).

The pitch that can be used in the present invention is not limited as long as its softening point is fiber-forming.
It is preferably about 200 to 350 ° C. The number of the discharge holes of the nozzle mouthpiece (1) is not particularly limited, and usually about 80 to 300 holes per one mouthpiece. The spinning temperature in this case depends on the pitch used,
It is usually about 250 to 400 ° C. Also, the draft is 1
It is preferable to set it to about 00 to 500.

After discharging from the discharge holes, cooling is started.
As the cooling fluid in the above cooling, various cooling fluids such as heated air or heated steam are used. Within 150 mm directly below the die discharge surface,
It is preferable to cool from the range of 10 to 30 mm. When the cooling start position is above 150 mm, the appropriate cooling fluid temperature region becomes narrow, and the yarns usually come into close contact with each other due to yarn shaking. On the other hand, if it is less than 10 mm, the discharge amount unevenness is caused by the influence of the temperature unevenness on the spinneret surface, and the unevenness of the fiber diameter and the yarn breakage occur, which makes stable spinning difficult.

Next, the fluid discharged from the spinning cooling chamber (7) (yarn associated flow (13)) consists of a fluid for cooling just below the spinneret surface and a low boiling point substance generated from the yarn. The associated flow rapidly increases from the solidification point and increases, and the low boiling point substance diffuses into the associated flow. Therefore, in order to control the accompanying flow generated without impairing the spinnability, an air flow corresponding to the flow rate of the accompanying flow is supplied to the air supply port (5 in the direction opposite to the yarn bundle take-up direction during spinning in the spinning cooling chamber. ). The flow rate of air supplied from the air supply port in this case is such that it is discharged from the spinning cooling chamber by the yarn accompanying flow, and it is not preferable that it is supplied by forced pressure insertion. The reason for this is that it is desirable for the safety and hygiene of the operator to manage the spinning cooling chamber so that the pressure is slightly lower than atmospheric pressure.

Further, it is preferable to discharge a larger amount of air than the yarn accompanying flow rate from the spinning cooling chamber, and therefore a yarn drawing by a suction gun for discharging together the yarn accompanying flow and the air in the spinning cooling chamber together. The taking method is suitable. However, when the yarn is taken up by a roller, it is desirable to install a suction gun in the vicinity of the yarn take-up line to keep the spinning cooling chamber in a slightly depressurized state.

In this way, the turbulence of the fluid due to the collision between the yarn accompanying flow discharged from the spinning cooling chamber and the supply air has already been thinned at the collision position, and the air is supplied to the yarn. Since it is arranged in the peripheral part around the exhaust part of the accompanying flow, it does not cause a sudden temperature change. Therefore, the yarn is stable in the cooling region and the yarn does not break even if the yarn shakes. Further, the effect of the present invention is exerted as the number of the spinning yarn weights is plural in one spinning cooling chamber. That is, as the air supply port is closer to the direction perpendicular to the yarn direction, the turbulence of the air flow near the thinning point is more likely to occur, so cooling spots are more likely to occur unless the spinning cooling space has a considerable volume. However, spinnability is impaired.

The yarn bundle pulled by the suction gun (3) is traversed through the fiber-opening tube (9) and formed into a sheet by a sheet forming device to form a pitch fiber sheet. On the other hand, the fluid that accompanies the yarn bundle is usually collected together with the yarn bundle by an air fluid such as a suction gun and is suction-guided by the sheet forming device.If the above-mentioned take-up is a godet roller, the accompanying flow collection up to the godet roller is performed. Guided to the duct. The induction duct is connected to a suitable separation device, for example, a bag filter, and low-boiling substances are continuously separated and captured. For this reason, the surrounding environment outside the spinning cooling chamber is not contaminated, and it is possible to carry out melt spinning at a stable pitch for a long period on an industrial scale.

[0017]

EFFECTS OF THE INVENTION According to the present invention, since the yarn accompanying flow generated during spinning can be controlled, stable spinnability can be achieved, and diffusion of low boiling point substances can be prevented, resulting in the final product. It is possible to exert excellent effects in improving quality, operability, and safety.

[0018]

EXAMPLES Examples will be shown below to clarify the characteristics of the present invention.

Example 1 A coal-based pitch having a softening point (SP) of 280 ° C. measured by the Mettler method was set to a spinning temperature of 330 ° C. by using the spinning device shown in FIG. 1, and the diameter of the spinneret discharge hole was 0.4 mm and the number of holes was 130 holes. Was spun into a draft 200 at a discharge amount per spinneret of 100 g / min to produce a pitch fiber sheet. The area of the air supply port at this time is 0.1 square meter, and the air supply port communicating with the air outside the spinning chamber is sucked by the duct so that the air supply direction is opposite to the yarn take-up direction. It was installed on the peripheral surface of the gun (4), and the adjustment valve (6) was set so that the amount of air supplied would be about 0.3 m ³ / min (supply type III). Table 1 shows the evaluation results of the spinning operability and the environmental conditions around the spinning chamber at this time.

The above evaluation methods in the examples and comparative examples of the present invention were carried out by continuous spinning for 48 hours while measuring the total number of single yarn breakages and sensory test of the surrounding environment. The spinning operability is as follows: A: 48 hours spinning without single thread breakage, B: 48 hours spinning with 50 single thread breaks within 50 times, C: 48 frequent single thread breaks
Those which did not endure time spinning are shown. In addition, the above-mentioned surrounding environmental condition (environmental) depends on the presence or absence of odor and low boiling point substances,
0 is not recognized by both, 1 is slightly odorous, 2
Indicates that odor and outflow of low boiling point substances were observed.

Example 2 The same procedure as in Example 1 was carried out except that the spinning rate was 150 g / min per spinneret. The results are shown in Table 1.

Example 3 A coal-based pitch having a pitch softening point of 300 ° C. was used, a spinning temperature of 340 ° C., a discharge rate of 150 g / min, and a draft of 25.
The procedure was the same as in Example 1 except that the value was 0. The results are shown in Table 1.

Comparative Example 1 The direction of the air supply port was changed so that the position of the air supply port was in the same direction as the yarn take-up direction, and the air supply port communicating with the air outside the spinning chamber by the duct was cooled (2). The same procedure as in Example 1 was carried out except that the circular shape was provided immediately below (feed type I). The results are shown in Table 1.

Comparative Example 2 The direction of the air supply port was changed so that the position of the air supply port was perpendicular to the yarn take-up direction, and the air supply port communicating with the air outside the spinning chamber by the duct was laterally blown ( Supply type
The procedure was the same as in Comparative Example 1 except for II). The results are shown in Table 1.

Comparative Example 3 The procedure of Comparative Example 1 was repeated except that the discharge rate was 150 g / min. The results are shown in Table 1.

Comparative Example 4 The procedure of Comparative Example 1 was repeated except that the discharge rate was 150 g / min, the draft was 250, and the air supply direction was supply type II. The results are shown in Table 1.

From the above results, it is clear that in the method of the present invention, there is no leakage of low volatile components from the spinning cooling chamber for 48 hours, continuous spinning can be carried out without trouble such as single yarn breakage, and excellent effects are exhibited. is there.

Further, the pitch fiber sheets (600 g / m ² basis weight) obtained in the examples are B after inactivating treatment after infusibilization.
An average of 1550 m ² / g of activated carbon fibers was obtained by the ET measurement method. On the other hand, in Comparative Example, since the air supply direction which is a requirement of the present invention is not satisfied, not only is it difficult to perform continuous spinning for a long time due to frequent occurrence of yarn breakage during spinning, but low volatility from the spinning cooling chamber Leakage of components was observed, and the environment around the spinning room was significantly contaminated. When they are not melted, partial combustion and hot dust occur, the processing temperature becomes unstable, and the sheets have to be excluded from the production line, which seriously hinders operability.

[0029]

[Table 1]

From the above results, it is understood that the pitch melt spinning method of the present invention exerts an excellent effect on its spinnability and the like.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a pitch fiber manufacturing apparatus of the present invention.

FIG. 2 is a diagram showing the concept of how supplied air flows as a yarn collateral flow in the spinning cooling chamber in the pitch fiber manufacturing apparatus of the present invention.

[Explanation of symbols]

 P ... Melt pitch Y ... Thread 1 ... Nozzle mouthpiece 2 ... Cooling device 3 ... Suction gun 4 ... Isolation wall 5 ... Air supply port 6 ... Regulator valve 7 ... Spinning cooling chamber 8 ... Connection part 9 ... Opening cylinder 10 ... Sheet Holding wire mesh 11 ... Suction container part 12 ... Guide duct 13 ... Yarn collateral flow S ... Pitch fiber sheet

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Kazuo Tai 1-162 Ujinokami, Uji-shi, Kyoto (72) Inventor Megumi Kibe 38 Mise-cho, Kashihara-shi, Nara Skyhite 203 Kashihara Jingumae 203 (72) Inventor Yoji Sato 2-37 Nishichiyogaoka, Nara City, Nara Prefecture (72) Inventor Yoshinori Higashi 1-145 Ujinokami, Uji City, Kyoto Prefecture

Claims (1)

[Claims] 1. A method for melt-spinning a pitch, characterized in that, when pitch fibers are produced from petroleum-based or coal-based pitch, an air flow is supplied in a direction opposite to the yarn collateral flow from the spinning cooling chamber.