JPS5938323B2 - Carbon fiber continuous heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses carbon fibers (hereinafter referred to as carbon fibers)
The present invention relates to a heat treatment apparatus using high-frequency plasma that performs graphitization processing at high speed and continuously by heating to around .000°C.

For example, acryloni) IJ-based polymeric fibers are heated in an oxidizing atmosphere at a temperature of 200°C to 500°C as a primary heat treatment, and then heated at a temperature of about 500°C to about 3000°C, or substantially It is well known that carbon fibers with significantly higher tensile strength and flexibility can be obtained by heating in an oxidizing or inert gas atmosphere at higher temperatures until carbon sublimes.

The present invention is an apparatus that performs the latter, that is, secondary heat treatment, called graphitization treatment, at high speed and continuously in an inert gas atmosphere, which not only greatly increases productivity compared to conventional apparatus. Since it is small, inexpensive, and consumes little power, it has the advantage of extremely low initial investment.

Conventionally, this graphitization process mainly uses an electric furnace in an inert gas atmosphere or a high-frequency induction heating device, but in order to maintain a temperature of 3,000°C or more for at least a certain period of time, it requires a large amount of electricity and requires the use of insulating materials. etc. costs are high.

The method of controlling the atmosphere is difficult and there is a lot of wasted time when raising and lowering the temperature.
In other words, since the device is large and has a large heat capacity, there are drawbacks such as a large amount of downtime, such as idle time during sample exchange, which poses a major problem in terms of carbon fiber productivity and, therefore, cost.

The present invention eliminates these drawbacks and will now be described in detail with reference to Examples.

The drawing is a sectional view showing a structural outline of an example of a carbon fiber graphitization processing apparatus or furnace in which the present invention is implemented.

In this figure, 1 and 11 are the upper and lower chambers (partition or furnace chamber), 2 is the gas input, and 5
, 6.7 are the outer nozzle, inner nozzle, and outer tube of the plasma generator, respectively, and these chambers are all evacuated and filled with argon A.
The chamber 1 has a carbon fiber take-up roll 3 and a roller 4, and the chamber 11 has a carbon fiber take-up roll 12 and a belt 13 winding drive motor 14 as shown in the figure.

8 is a plasma regulating gas inlet, and 9 is a work coil for high frequency induction heating, which is connected to a high frequency oscillator (not shown).

10 is carbon fiber to be heat treated, for example 10-2
00μφ×100 stranded wires.

Reference numeral 15 indicates a valve, and reference numeral 16 indicates a needle valve. Exhaust pipes 23 and 24 into which these are inserted are connected to an inlet of a vacuum device such as an oil rotary vacuum pump (not shown) to evacuate the chamber.

22 is a plasma trigger (excitation) bundle, 22a
A quartz rod is used for the part 22b, a 5O8 (stainless steel) connector is used for the part 22b, a carbon (carbon or graphite) rod or a tungsten rod for welding is used for 22C, and the carbon rod 22c is covered with the bundle 22. It can be placed close to the center of the plasma generator outer tube 7 containing the treated carbon fiber 10 or moved away from the outer tube 7.

17 to 21 show examples of positions of 01J for sealing.

Next, the operation of this device will be explained.

First, after vacuuming both chambers, argon A (or helium He) is flowed in from the gas manpower 2 and the inner nozzle 6,
A high frequency current is passed through the work coil 9 from a high frequency oscillator.

Here, operate the trigger bundle 22 and release the carbon rod 22.
When c approaches the center of the plasma generator 1, plasma or plasma torch P is formed between the inert gas such as argon discharged from the inner nozzle and the red-hot carbon rod 22c by the high-frequency induced current, and a high-temperature plasma region is generated. Occur.

This method of generating plasma is called the electrodeless discharge method.
It is well known that A s He is formed when a gas such as As He is raised to its ionization temperature in an induced electric field created by a radio frequency current.

Now, once the plasma is generated, the trigger bundle 2 will be activated again.
2 to move the carbon rod away from the plasma area P,
Also, the high frequency power of the work coil 9 is increased.

At the same time, a relatively inert and slightly high ionization tendency N2 (N2) gas from the plasma adjustment gas population 8 is introduced little by little, and the plasma torch P is moved into the plasma generators (5 and 7).
), and the speed of the take-up motor 14 is adjusted so that the carbon fiber 10 reaches the temperature at which it graphitizes and passes through the plasma for a certain period of time, such as 10 seconds at 6000°C.

Note: The heating temperature of the Bon fiber 10 is determined by the high frequency power of the work coil, the flow rate of A or He gas fed in from the gas inlets 2 and 6, the flow rate of N2 gas fed in from the gas inlet 8, and the rotational speed of the take-up motor 14. It can be determined by adjusting the

Furthermore, the gas inlet 8 has a plurality of nozzles t″L, N
The two gases are configured to flow uniformly within the plasma generator, and its effects include focusing the plasma region and cooling the inner wall of the plasma generator.

The role of the pipe 24 and the needle pipe 16 is to adjust the flow rate of exhaust gas during operation of the apparatus and to control the atmospheric pressure within the chamber.

As described above, the carbon fibers passed through the high-temperature plasma at an appropriate speed are uniformly graphitized and wound up continuously. However, in the device of the present invention, the furnace structure is simple and the high-temperature heating part is located in the air. The atmosphere inside the furnace is perfect because it can be contained without being affected by high heat, and the material to be processed can be replaced immediately by cutting off the input from the high-frequency oscillator, so the down time of the equipment is compared to conventional equipment. Industrially advantageous effects can be obtained, such as a significantly shorter heating time, the required high temperature being easily obtained, and the required value of high frequency power being significantly lower than that of conventional heating furnaces, resulting in less power consumption.

Furthermore, although the above explanation is about heat treatment of carbon fibers, the present invention is not limited to heat treatment of carbon fibers. It can also be used for annealing.

[Brief explanation of the drawing]

The drawing is a sectional view showing an outline of the structure of a high-temperature heat treatment apparatus for carbon fiber, which is an embodiment of the present invention. 1.11... Chamber, 2,6... Gas inlet, 3.12... Winding drum, 4...
...Roller, 5゜6.7...Outer nozzle, inner nozzle, outer tube of plasma generator, 8...Plasma adjustment gas inlet, 9...High frequency work coil, 1
0...Carbon fiber, 13...Bell), 14...Motor, 15...Pal 7/, 16...Needle pal 7 ', 17~
21...0 ring, 22...trigger bundle, 22a...quartz rod, 22b...
・・Stainless steel connector, 22c・・Carbon rod, 23.24・・Exhaust pipe, P・・・・・
plasma area.

Claims (1)

[Claims] A first chamber that houses carbon fiber strands that have been subjected to the 11th heat treatment and continuously sends them out, and an inert gas such as argon that is flowed into the chamber that is evacuated. communicating with a second chamber housing a device that communicates with a high-frequency electric field to generate plasma and a device that continuously winds the carbon fiber strands that have passed through the plasma and undergone graphitization heat treatment;
A continuous heat treatment apparatus for carbon fibers, characterized in that the carbon fiber strands drawn out from the first chamber continuously pass through the plasma region at a constant speed. 2. The continuous heat treatment apparatus for carbon fibers according to claim 1, wherein the plasma area is limited by uniformly flowing nitrogen gas around the plasma.