JPS58136833A - Spinning device for pitch carbon fiber - Google Patents

Abstract

PURPOSE:The titled device in which the spinning nozzle is made of high heat- resistant ceramic with larger heat capacity than metal and the heater is set near the spinning nozzle, thus enabling the uniformization and optimization of the pitch in its spinning viscosity. CONSTITUTION:In the production of pitch carbon fiber, the spinning nozzle for pitch as a starting material is made of sintered ceramic with a larger heat capacity than metal and high heat resistance and a heater is set near the spinning nozzle to keep each spinning orifice at the optimum temperature for pitch spinning. The above heater is preferably embedded in the above spinning nozzle. Further, it is much preferred that the spinning nozzle is prepared by laminating a polurality of ceramic green sheets having heater on their surfaces, and sintering them so that the heaters are contained inside of the nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spinning device for pitch-based *fine fibers, and particularly to a spinning nozzle thereof.

Carbon fiber has excellent properties such as weight reduction and wear resistance, and composite materials of carbon fiber and synthetic resin or metal are attracting attention as structural and functional materials for automobiles, aircraft, etc.

Currently, the mainstream carbon fiber is polyacrylonitrile (PAN), and fibers with high strength and high modulus are commercially available. However, in recent years, interest has been growing in pitch-based carbon fibers, especially mesophase-containing pitch-based carbon fibers, because they can be produced at low cost and do not involve complicated processes, and there is an urgent need to establish a method for producing them. However, despite its usefulness, a method for producing continuous fibers of high-quality mesophase-containing pitch-based carbon fibers has not been established.

P, a PAN-based carbon fiber raw material that is currently our nemesis.
Since AN is expensive, raw material costs account for a large proportion of the manufacturing cost, and it is difficult to reduce the price significantly below the current level. In addition, products using PAN as a starting material provide carbon fibers that are difficult to graphitize, and have the complicated manufacturing process of having to be subjected to ununiformization and graphitization treatments under tension in order to improve the molecular orientation. be.

On the other hand, in the case of mesophase-containing pitch fibers, they are easily graphitized and have excellent molecular orientation. Also, the raw material is cheaper than PAN and it is advantageous in terms of cost. However, the viscosity of the thermally-reacted pitch, which is the spinning raw material, changes greatly depending on the temperature, and the elongation is also quite low, so melt-spinning pitch has traditionally been a national problem.
This is a cause that hinders practical application.

The manufacturing process for pitch-based carbon fibers can be broadly divided into a heat treatment process for raw material pitch and a subsequent spinning process, but there are still problems to be solved in each process.

The object of the present invention is to improve the equipment used in the spinning process, particularly the spinning nozzle. Further, the present invention provides a spinning nozzle in which the entire nozzle body is maintained at a predetermined temperature and with a uniform temperature distribution, so that raw material pitch of uniform viscosity is spun from all spinning holes of the nozzle body under uniform temperature conditions. With the goal.

By the way, metal materials have traditionally been used as spinning nozzles.
A heater member is provided around the spinning nozzle as a means for keeping the spinning nozzle at a predetermined temperature. However, in this spinning nozzle, the outer periphery near the heater member is hotter than the center, causing temperature variations in each spinning hole. In addition, measures have been taken to energize the spinning nozzle itself, but
When energization is controlled to prevent overheating of the metal material, the temperature of the spinning nozzle also periodically fluctuates accordingly. Such variations and changes in temperature at each spinning hole have relatively little effect when spinning synthetic fibers, but in the case of pitch-based fibers, the viscosity of the raw material pitch changes depending on the temperature, as described above. Since the temperature varies greatly, it is inappropriate to use a conventional spinning nozzle having a dispersion in temperature distribution.

A feature of the present invention, which provides an effective solution to the above-mentioned pongee and achieves the above object, is that the spinning nozzle is made of hexaramic, which has a larger heat capacity than metal and has good heat resistance. .

Examples of such ceramics include alumina, zirconia, and cordierite. For example, alumina has approximately twice the heat capacity and thermal conductivity of approximately 1/1 that of iron.
It is o. Therefore, if such a ceramic spinning nozzle is used and a heater member is arranged around the outer periphery, it will take a little longer to heat the entire body to a predetermined temperature compared to a metal spinning nozzle, but once heated, the outer periphery will The gradient of the temperature distribution between the outermost part and the center part is also extremely small, and the outermost part near the heater member is unlikely to overheat, and even if the heater member is energized for temperature control, there will be no sudden temperature change. Therefore, the entire spinning hole of the spinning nozzle can always be kept at a substantially uniform temperature.

Further, a great advantage of constructing the spinning nozzle from ceramic is that a heater member can be embedded within the spinning nozzle.

By positioning this heater member around each spinning hole, the temperature of each spinning hole can be maintained even more uniformly. Therefore, each spinning hole can be maintained at the optimum temperature for spinning the raw material pitch, and the occurrence of yarn breakage can be significantly reduced compared to metal spinning nozzles.

Examples of the present invention will be described below.

A slurry made by adding a binder, a binder, a solvent, and a ball mill to alumina powder was used.
- A plurality of green sheets each having a side of 120 cm were produced. 4 green sheets with a thickness of 25cm and a thickness of 1.2cm
Eighty-five spinning holes were formed in two 5-sized green sheets, which were distributed in a nearly uniform positional relationship. And board thickness 25■
On the surface of each of the four green sheets of the board 4t25 and one of the green sheets of the board 4t25■, each spinning hole 3 is formed as shown in Fig. 2 (the green sheet becomes circular in shape due to subsequent processing). The heater 4 was formed by screen printing molybdenum paste between the two.

Next, as shown in Figure 1, a green sea plate with a thickness of 15 m)
Overlap 1 m, 1 b, 1 c, 1 d,
From below, the temperature is 150℃ and the pressure is 50/d.
The green sheets 1a, 1b and IC were sandwiched together and made into a laminate under the following conditions.

1d and 2b are provided with through-holes P5m and 5b at positions that contact both ends of the heater, as shown in FIG.
In this, a platinum lead wire 6 with a diameter of 05 cm is used as a lead electrode.
Insert a and 6b.

Next, the outer shape of the laminate is formed into a circular shape, and the spinning holes 5
was processed into a tapered shape. This integrated product was then fired in a humidified hydrogen atmosphere at a temperature of 1,650° C. for 4 hours to obtain a sintered body with an integrated structure. The circular outer circumference of the obtained sintered body has a diameter of 80 holes, the upper diameter of the tapered spinning holes 5 is 2 mm, and the lower diameter is α4.
■It was. Note that the clearance between the through holes 5m, 5b and the lead wires 6m, 6b inserted therein is filled by the shrinkage of the ceramic during firing, and the lead wires 6a,
6b are fixed in contact with both ends of the heater 4, respectively. The resistance of the heater 4 was set to 5Ω in each case by adjusting the thickness of the paste.

The spinning nozzle prepared in this way was attached to a conventionally used melt spinning device, and the raw material pitch was melt spun at a spinning temperature of 375°C and a spinning speed of 270 m/min for 1 hour and wound onto a bobbin. As a result, no thread breakage occurred. The obtained pitch fiber has a fiber diameter of 9.
When it was made infusible, carbonized, and further graphitized using a conventional method, it had a tensile strength of 250 Kf/-1 and a tensile modulus of 55 x 10 Kg/-.

In addition, when a ceramic nozzle body with the same shape as the above-mentioned spinning nozzle was made, a micro-heater was attached to its outer periphery, it was attached to a melt-spinning device, and spinning was performed under the same conditions as above. Although thread breakage occurred, much better results were obtained compared to metal nozzles.

As explained above, in order to prevent yarn breakage and improve spinning performance when spinning carbon fiber using pitch, the spinning nozzle is made of ceramic, which has a higher heat capacity than metal. The spinning nozzle can be heated so that the entire spinning nozzle is maintained at a uniform temperature, and therefore each spinning hole can be maintained uniformly at the optimum temperature, thereby preventing yarn breakage from occurring in a part of the spinning hole. Almost completely preventable. Furthermore, since ceramic has excellent corrosion resistance against pitch, it is also possible to improve the durability of the spinning nozzle.

[Brief explanation of drawings]

The figure shows an example of a spinning nozzle according to the present invention.
FIG. 1 is a front view, and FIG. 2 is a sectional view taken along the line 1-1 in FIG. 1, showing the upper surface of No. 211 constituting the spinning nozzle. 1a, 1b, IC, 1d, 2m, 2b...
Laminated member 3...Spinning hole 4...Heater member 6m, 6b...Lead wire bush 1 diagram

Claims (3)

[Claims] (1) A spinning device for undetermined pitch fibers, characterized in that the spinning nozzle for spinning raw material pitch is made of a ceramic sintered body having a larger heat capacity than metal, and a heater member is installed in the vicinity of the spinning nozzle. Spinning equipment for pitch yarn carbon fiber. (2) The spinning device for undetermined pitch fibers according to claim 1, wherein the heater member is embedded in the spinning nozzle made of a ceramic sintered body. (3) A pitch undetermined elemental fiber according to claim 2, wherein a large number of ceramic green sheets each having the heater member provided on the surface thereof are laminated and sintered to constitute a spinning nozzle having a heater member inside. Spinning equipment.