JPS6257925A - Method and apparatus for producing carbonized fiber - Google Patents

Abstract

PURPOSE:To obtain a carbonized fiber having low variation of properties along the cross-sectional direction, by irradiating a raw material fiber with light from whole circumferential directions in a plane perpendicular to the fiber axis of the raw material fiber in a non-oxidizing atmosphere. CONSTITUTION:The reaction tube 1 is surrounded with the spheroidal mirror 15. A point light source 17 connected to a power source 16 is placed in the spheroidal mirror in a manner that the light emitted from the light source is reflected by the spheroidal mirror 15 and focused to the core axis of the reaction tube 1 from whole circumferential directions in a plane perpendicular to the core axis and from almost all directions other than the above. The point light source has a spectrum mainly in visible range and infrared range.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for producing carbonized fibers, and more particularly to a method and apparatus for producing carbonized fibers using light energy.

BACKGROUND OF THE INVENTION For example, carbon fibers are manufactured by heating raw material fibers such as polyacrylonitrile fibers in an oxidizing atmosphere to make them flame resistant, and then heating them in a non-oxidizing atmosphere to carbonize them. Carbon fibers produced in this way are further heated at high temperatures in an inert atmosphere to graphitize them, thereby obtaining graphite fibers having a much higher modulus of elasticity than carbon fibers. However, the above carbonization and graphitization usually involve
A resistance heating furnace or an induction heating furnace is used. Plasma heating furnaces and arc heating furnaces may also be used.

However, all of these heating furnaces have disadvantages, such as requiring a large-capacity power source, cooling means such as a water cooling device, and the need for troublesome temperature control. .

On the other hand, Japanese Unexamined Patent Publication No. 54-15682j describes an apparatus for producing graphite fibers using solar energy. This device receives sunlight with a plane mirror equipped with a tracking device, focuses it with a parabolic mirror, and irradiates the carbon fiber from only one direction in a plane perpendicular to the fiber axis. It is made of a material that is heated to graphitize it. There is also a description that optical energy can be used instead of solar energy. This device does not require a special heat source if it uses sunlight. However, since the energy of sunlight is greatly affected by weather and other factors, an auxiliary heat source and heat storage device are required. It also requires an expensive tracking device.

Furthermore, temperature control is almost impossible. Although the above-mentioned problems do not arise when optical energy is used, a large-scale optical system is required to make the light parallel to the parabolic mirror. What is even more problematic is that the above-mentioned conventional devices, regardless of whether solar energy or optical energy is used, do not allow light to be applied to carbon fibers from only one direction in a plane orthogonal to the fiber axis. Since the carbon fibers are irradiated with light, there is a large temperature difference between the side that is irradiated with light and the opposite side that is not irradiated with light, and the carbon fibers are not heated uniformly. This heating unevenness is quite large because carbon fibers are usually in the form of strands (fiber bundles), and therefore there is a layer of gas with high heat insulation between each yarn, so it should never be ignored. Not 1q. Therefore, the obtained graphite fiber has significant unevenness in properties in its cross-sectional direction.

Problems to be Solved by the Invention It is an object of the present invention to solve the above-mentioned drawbacks of the prior art, and to not only make it possible to utilize light energy efficiently, but also to
An object of the present invention is to provide a method and apparatus capable of producing carbonized fibers with less unevenness in properties in the cross-sectional direction.

In order to achieve the above object, this invention focuses light energy on the raw material fibers in a non-oxidizing atmosphere to heat the raw fibers and ash the raw fibers. There is provided a method for producing carbonized fibers, characterized in that the light energy is focused from all directions in a plane orthogonal to the fiber axis of the raw material fibers. Further, in the present invention, as an apparatus for implementing the above method, a reaction tube made of a translucent material and equipped with a raw material fiber inlet and a carbonized fiber outlet, and a raw material fiber supply means provided on the side of the inlet. and a carbonized fiber winding means provided on the outlet side, an ellipsoidal mirror provided around the reaction tube, and a light source housed in the ellipsoidal mirror,
and the light source is arranged at a position where light reflected by the ellipsoidal mirror gathers from all directions on the core axis of the reaction tube and in a plane perpendicular to the core axis. An apparatus for producing carbonized fiber is provided.

In this invention, carbonized fiber refers to carbon fiber or graphite fiber.

In the present invention, raw material fibers refer to organic polymer fibers such as polyacrylonitrile fibers, recycled cellulose fibers, phenolic fibers, and pitch fibers heated in an oxidizing atmosphere when producing carbon fibers as carbonized fibers. refers to flame-resistant fibers obtained by Furthermore, in the case of producing graphite fibers as carbonized fibers, it refers to the above-mentioned carbon fibers. These raw material fibers, flame-resistant fibers, carbon fibers, and graphite fibers are usually all in the form of i-land.

In this invention, the raw material fiber is drawn out from the raw material fiber supply means, passed through the raw material fiber inlet into the reaction tube on its core axis, and then passed through the carbonized fiber winding means through the carbonized fiber outlet. The inside of the reaction tube is maintained in a non-oxidizing atmosphere.

Next, the raw material fiber supply means and the carbonized fiber winding means are operated to cause the raw material fiber to travel continuously within the reaction tube. In this state, a light source is turned on, and the light is reflected by an ellipsoidal mirror and focused onto the running raw material fiber. This focused light energy heats the raw material fibers, but the light reflected by the ellipsoidal mirror hits the light source from all directions on the core axis of the reaction tube and in a plane orthogonal to the core axis. Because they are arranged in a location where they gather, the raw material fibers are heated uniformly from all directions in a plane perpendicular to the fiber axis.
When the raw material fiber is flame-resistant fiber, carbon fiber is obtained, and when it is carbon fiber, graphite fiber is obtained.

Embodiment To explain this invention in detail based on one embodiment, in FIG. 1, a reaction tube 1 is made of a heat-resistant and translucent material such as quartz glass or ceramics. , has a cylindrical shape as a whole, and a raw material fiber inlet 2 and a carbonized fiber outlet 3 are provided on the core axis at the end, and a gas inlet 4 and a gas outlet 5 are provided in the vicinity thereof.
is provided.

On the introduction port 2 side, a raw fiber supply means 8 having a rotation guide 6 and means for supporting a package 7 of raw fiber Y is provided. The package support means may be those commonly used in the textile industry. Among these, it is preferable to use one with a brake mechanism that can send out the raw material fiber Y with a constant tension. Moreover, means 9 for winding up the carbonized fiber C is provided on the outlet port 3 side. This carbonized fiber winding means 9 includes a rotary guide 1
0, has a winding bobbin 11, and the winding bobbin 11 is connected to the reducer 1
2 and is driven by a motor 13. The driving speed of the winding bobbin 11 needs to be gradually reduced according to the amount of winding of the carbonized fiber C formed thereon.
A speed controller 14 is connected to the motor 13, and the rotational speed of the motor 13 is gradually reduced according to the winding diameter to reduce the carbonized fiber C.
The peripheral speed of the package 18 is always kept constant. Such so-called winding control mechanisms may also be well known.

A spheroidal mirror 15 is provided around the reaction tube 1. This spheroidal mirror 15 can be divided into two parts, but when assembled, it forms an ellipsoid.

Further, the spheroidal mirror 15 houses a point light source 17 connected to the electric FF 116. Thus, the light emitted from this point light source 17 is reflected by the spheroidal mirror 15 as shown in the figure, and from all directions on the core axis of the reaction tube 1 and in a plane orthogonal to the core axis. It is also located in a location where it can be seen from almost all other directions. As a point light source, one having a continuous or discontinuous spectrum mainly in the visible region or infrared region is used, such as a halogen lamp, a cubenone lamp, an infrared lamp, or a carbon dioxide laser. Therefore, it is preferable to select and use a point light source that includes a wavelength at which the raw fiber exhibits an absorption peak, depending on the type of raw fiber.

In the above, in order to improve the sealing performance of the atmospheric gas, the gas inlet 4 and the gas outlet 5 are connected to a chamber 21 connected to the reaction tube 1 via seal members 19 and 20, respectively, as shown in FIG. .22 can also be provided. In this case, the raw material fiber supply means 8 shown in FIG. 1 is accommodated in the chamber 21. Similarly, carbonized fiber winding means 9
are accommodated in the chamber 22 except for the speed controller 14.

FIG. 3 shows that in order to further improve the sealing performance of the atmospheric gas, the winding bobbin 11 of the carbonized fiber winding means in the apparatus shown in FIG. This is necessary if it can be done from outside.

In this case, a clutch may be interposed on the drive shaft between the vj1 stone 23 and the winding bobbin 11.

In the apparatus shown in FIGS. 1 to 3, the raw material fiber supply means may be configured to be similar to the carbonized fiber winding means.

As the ellipsoidal mirror, not only the spheroidal ellipsoidal mirror as described above but also an ellipsoidal mirror 25 whose reflecting surface is a simple ellipsoidal surface as shown in FIG. 4 can be used. in this case,
The elongated light source 26 can be used instead of a point light source, and the raw material fiber Y can be heated in the fiber axis direction in a range corresponding to the lengths of the ellipsoidal mirror 25 and the elongated light source 26. Become. However, if one elliptical mirror 25 is placed on one side of the raw fiber Y, there will be parts where the light shines directly and parts where it does not, so when using such an ellipsoidal mirror 25, the fifth As shown in the figure, a plurality of light beams (four in this example) are equally distributed around the raw fiber so that light is irradiated from multiple directions simultaneously in a plane orthogonal to the fiber axis of the raw fiber. In the apparatus shown in FIG. 4, a heat soaking tube 27 made of a material having heat resistance and excellent infrared absorption characteristics, such as graphite, is disposed on the core axis of the reaction tube 1. Of course, the equalizing tube can also be used in the apparatus shown in FIGS. 1 and 2.

The operation of the apparatus shown in FIG. 1 will be explained in the case of producing carbon fibers. In this case, flame-resistant fibers are used as the raw material fiber NY, and the flame-resistant fibers are heated and carbonized to obtain carbon fibers.

That is, 1q of carbonized fibers in this case are carbon fibers.

Now, first, the raw material fiber Y (flame-resistant fiber) is pulled out from the package 7 and passed through a so-called yarn path that passes through the rotating guide 6, the raw fiber inlet 2, the reaction tube 1, the carbonized fiber outlet 4, and the rotating guide 10. Wind it around the winding bobbin 11. Thereby, the raw material fiber Y passes precisely on the core axis of the reaction tube 1. On the other hand, an inert gas such as nitrogen gas or argon gas is continuously introduced into the reaction tube 1 through the gas inlet 4 and is discharged through the gas outlet 5.

That is, the inside of the reaction tube 1 is maintained in a non-oxidizing atmosphere. In addition, the point light source 17 is turned on, and the temperature of the core axis of the reaction tube 1 is 800.
Adjust the temperature to a desired temperature between ~2000°C.

The temperature is regulated by power supply 16.

In this state, the motor 13 is driven to drive the winding bobbin 11 via the reducer 12. The rotational speed of the winding bobbin 11 is regulated by a speed controller 14 so that winding is always performed with the same tension. Then, the raw material fiber Y is heated by the light from the point light source 17 that is irradiated from all directions on the core axis of the reaction tube 1 by the spheroidal mirror 15 in a plane orthogonal to the core axis, and also from other directions. , carbonized fiber (carbon fiber) C is obtained.

Decomposition gas, sublimate, etc. generated during carbonization are carried away by an inert gas and discharged outside the reaction tube 1.

In the above, if carbon fiber is used as the raw material fiber and the heating temperature is 2000° C. or higher, graphite fiber can be obtained as the carbonized fiber.

If a device is used in which the raw material fiber supply means is configured in the same way as the carbonized fiber winding means, for example, carbon fibers are first manufactured using flame-resistant fibers as the raw material fibers, and the carbon fibers are wound up on the carbonized fiber winding means. What is the case where the carbonized fiber winding means is used as a raw material fiber supplying means, and the raw material fiber supplying means is used as a carbonized fiber winding means to manufacture carbon fiber inside a reaction tube? Graphite fibers can be produced by passing in the opposite direction to graphitize. Further, processing while stretching is also possible.

The operation of the apparatus shown in FIGS. 2 to 5 is also exactly the same as that shown in FIG. 1 above. However, in the case of the device shown in Figure 3,
Since the winding bobbin 11 and the speed reducer 12 are connected through the la5, there is no possibility that the decomposed gas or sublimate will contaminate or corrode the speed reducer 12 or the motor 13. However, in an apparatus using a soaking tube 27 as shown in FIG. 5, the raw material fibers are heated more uniformly than in the case where the soaking tube 27 is not used.

Hereinafter, this invention will be explained in more detail based on Examples.

Example Carbonized fibers were produced using the apparatus shown in FIG. The raw material fiber used was a flame-resistant fiber obtained by flame-resistant polyacrylonitrile fiber with a single yarn diameter of 8 μm and a single yarn count of 3000. A transparent quartz tube with an outer diameter of 40 mm was used for the reaction tube 1.
Replace the reaction tube 1 and chamber 21 and 22 with nitrogen gas, and roughly introduce 2500cc/nitrogen gas from the gas inlet 4.
The gas was continuously supplied in minutes, and the gas was discharged from the gas outlet 5. Further, a 3.5 KW halogen lamp was used as the point light source 17.

In this state, 20 m of the flame-resistant fibers were placed inside the reaction tube.
While running continuously at a speed of m/min, a halogen lamp was turned on, and the flame-resistant fibers were heated to about 2000° C. and carbonized to obtain carbon fibers.

Next, do the same as above, but replace the halogen lamp in step 5.
The above carbon fibers were continuously passed through the reaction tube at a speed of 15 mm/min using a 4KW xenon arc lamp and nitrogen gas replaced with argon gas.
The mixture was heated to 400'C to graphitize it to obtain graphite fibers.

When the tensile strength and tensile modulus of the above graphite fiber were measured, the tensile strength was approximately 210 KQ/mm2, and the tensile modulus was approximately 53 tons/mm2.

Effects of the Invention The method of the present invention irradiates the raw fiber with light from all directions in a plane perpendicular to the fiber axis of the raw fiber, so the heating of the raw fiber is faster than in the conventional method in which the raw fiber is irradiated with light from only one direction. It is possible to produce 1q of carbonized fibers with very little unevenness in properties in the cross-sectional direction. Moreover, in this invention, such light irradiation is performed using an ellipsoidal mirror and a light source housed in the ellipsoidal mirror, so that not only can light energy be used efficiently, but also the above-mentioned Unlike conventional devices, there is no need for a large-scale optical system to make the light from the light source parallel. of course,
Unlike when using sunlight, the energy supply is not affected by the weather, and there is no need for an auxiliary heat source or heat storage device.

[Brief explanation of the drawing]

The drawings are all related to the present invention; FIG. 1 is a partial side view schematically showing an apparatus according to one embodiment, and FIG. 2 is a schematic partial side view showing another embodiment of the apparatus. Figures 3 and 3 are schematic partial side views showing main parts of a device in another actual IM mode, and Figures 4 and 5 show main parts of a device in another form. In the schematic drawings, FIG. 4 is a perspective view, and FIG. 5 is a plan view. Y: Raw material fiber C: Carbonized fiber 1: Reaction tube 2: Raw material fiber inlet 3: Carbonized fiber outlet 4: Gas inlet 5: Gas outlet 6: Rotation guide 7: Raw material fiber package 8: Raw material fiber supply means 9: Carbonized fiber winding means 10: Rotation guide 11: Winding bobbin 12: Reducer 13: Motor 14: Speed controller 15: Spheroidal mirror 16: Power source 17: Point light source 18: Carbonized fiber package 19: Seal member 20: Seal member 21: Chamber 22: Chamber 23: vi1 stone 24: Fj1 stone 25: m circular mirror 26: Long light source 27: Soaking tube

Claims (2)

[Claims] (1) When focusing light energy on raw material fibers to heat and carbonize the raw material fibers in a non-oxidizing atmosphere, the light energy is focused in all directions within a plane orthogonal to the fiber axis of the raw material fibers. A method for producing carbonized fiber, comprising: (2) A reaction tube made of a translucent material and equipped with a raw material fiber inlet and a carbonized fiber outlet, a raw material fiber supply means provided on the inlet side, and a carbonized fiber winding provided on the outlet side. an ellipsoidal mirror provided around the reaction tube; and a light source housed in the ellipsoidal mirror;
A carbonized fiber manufacturing apparatus characterized in that the elliptical mirror is arranged at a position where light reflected by the ellipsoidal mirror gathers from all directions on the core axis of the reaction tube and in a plane perpendicular to the core axis. .