KR0146890B1 - Apparatus and method for manufacture of anisotropic pitch - Google Patents

Abstract

The present invention is an improvement of the manufacturing method and apparatus of the anisotropic pitch proposed in Patent Application No. 16602 in 1993. In the conventional method and apparatus, the inert gas is blown in the present invention. By applying a vacuum, a large amount of pitch can be produced in a short time by effectively removing the volatiles accumulated in the reactor and lowering the boiling point of the volatiles as compared to the slightly pressurized state at the time of normal pressure or inert gas blowing. It is a method and apparatus for producing such anisotropic pitches, which does not use an inert gas and can reduce the economic burden compared to conventional methods and apparatus.

Description

Manufacturing method of anisotropic pitch

1 is an anisotropic pitch manufacturing apparatus proposed in Patent Application No. 16602 in 1993,

(a) is a cross-sectional view of cutting two rows of screws

(b) is a cross-sectional view of the raw material inlet to be visible

2 is a schematic view of an apparatus for producing anisotropic pitches in accordance with the present invention.

3 is a photograph of a pitch prepared by the method of the present invention and a cross section of the cross section under a polarized light.

(a) is prepared by the method of Example 4

(b) is prepared by the method of Example 5.

* Explanation of symbols for main parts of the drawings

1: Raw material pitch inlet 2: Gas outlet

3: gas inlet 4, 14: heater

4,15: screw 6: reactant outlet

10: Reactor 11: Raw material pitch inlet

11 ': Raw material pitch injection pump 16: Reactant outlet

16 ': exhaust reactant reservoir 17: vacuum control means

18: Vacuum trap 1 19: Vacuum trap 2

20: Vacuum detector 21: Vacuum control valve

22: vacuum regulator 23: vacuum pump

The present invention relates to a method and apparatus for producing an anisotropic pitch using a pitch as a raw material, and more particularly, to a method and apparatus for manufacturing an anisotropic pitch having a uniform mesophase content using a kneading extruder type reactor. will be.

In the production of pitch-based carbon fibers, low-strength general purpose carbon fibers are produced when isotropic pitch is used, whereas carbon fibers produced using anisotropic pitch not only exhibit high strength but also carbon fibers made from PAN fibers. It shows much higher modulus of elasticity than. As described above, since the anisotropic pitch is very useful as a raw material of high elastic modulus carbon fiber, much research has been conducted on how to effectively produce such anisotropic pitch.

In the manufacture of anisotropic pitches, Japanese Patent Laid-Open No. 58-134181, Japanese Laid-Open No. 58-168687, Japanese Laid-Open No. 61-271392 and Japan Japanese Patent Application Laid-Open No. 1-213396 is introduced.

However, the common drawbacks of these conventional methods are that since a certain manufacturing capacity is determined by each method, it is difficult to meet various demands from a small capacity to a large capacity by one method, and a means for effectively removing low molecular weight components is proposed. As a result, the processing time is considerably longer, and it is very difficult to obtain a homogeneous pitch without producing 100% anisotropic pitch.

In fact, the bulb pitch used for the production of carbon fiber uses a pitch having an anisotropy content of about 85-95%, so that the mixed isotropic pitch needs to be as uniform as possible. If the isotropic pitch is ubiquitous, it causes the physical properties of the final carbon fiber to deteriorate. Therefore, in order to effectively produce a homogeneous mesophase pitch having a low softening point, the pitch must be heat treated uniformly, local heating must be avoided, and the residence time of the pitch in the reactor must be constant. And the area of the interface of a liquid phase and a gaseous phase is large in a reactor. That is, the mesophase produced by the heat treatment should be mixed with the non-mesopaceous material continuously, and the surface area of the pitch in the reactor should be made as large as possible to effectively remove the low molecular weight component, which is a component that is not converted into anisotropic tissue in the raw material pitch. Because there is.

In order to solve the problems of the conventional methods and further provide a method for producing an anisotropic pitch more effectively, the present inventor proposed a method and apparatus for producing an anisotropic pitch in 1993 Patent Application No. 16602, which is a modified paddle ( When using a kneading extruder-pitch manufacturing apparatus equipped with two rows of skews in which paddles are combined according to the purpose of the reaction, they have a very large reaction surface area compared to a general reactor, and when rotating at a constant speed according to the combination of paddles, Apparatus and apparatus capable of obtaining a uniform pitch having a desired mesoface content by a short time reaction by controlling the residence time to be constant by controlling the flow of the vagina and the non-mesopaceous phase to be uniformly mixed and moving forward at a constant speed. Reacting while blowing inert gas at a constant rate using It was on a continuous manufacturing method of the Castle pitch.

1 (a) and (b) are cross-sectional views of a reactor which is an anisotropic pitch manufacturing apparatus of 1993 Patent Application No. 16602. When the reaction raw material is injected through the raw material inlet 1, the reaction is moved to the outlet 6 by the screw 5 while being heated to a constant temperature by the heater 4.

At this time, the inert gas of nitrogen is blown in through the gas inlet 3 installed in the upper part of the reactor, and the inert gas blown out is discharged to the outside through the gas outlet 2 together with the low boiling point component of the reaction raw material.

Although the reactor of FIG. 1 described above is very effective in producing a homogeneous anisotropic pitch, there has been a somewhat economic burden in terms of supplying a large amount of inert gas.

Although the present invention uses the same principle as the reactor of FIG. 1, in order to promote the reaction more effectively, the volatiles accumulated in the reactor are effectively removed by applying a vacuum without blowing an inert gas, and the atmospheric pressure or inert By lowering the boiling point of the volatiles compared to the slightly pressurized state at the time of gas injection, a large amount of pitch can be manufactured in a short time, and it is economical because there is no inert gas compared to the method of blowing a large amount of inert gas. It also has the advantage of being reduced.

As such, the present invention was devised to improve the method and apparatus for manufacturing the anisotropic pitch of Patent Application No. 16602 in 1993, and not only to reduce the economic burden by using an inert gas, but also to effectively produce a large amount of pitch in a short time. It is an object of the present invention to provide a device that can be manufactured and a method for producing an anisotropic pitch using the device.

Hereinafter, the present invention will be described.

The reactor used in the present invention is almost the same as the reactor proposed in 1993 Patent Application No. 16602 (hereinafter referred to as a conventional reactor), but the apparatus of the present invention, as shown in FIG. 3) to close the vacuum trap (18, 19), the vacuum sensor 20, the vacuum control valve 21, the vacuum regulator 22, the vacuum pump 23, etc. so as to maintain the inside of the reactor under reduced pressure instead. The vacuum control means 17 of the installation, and also to maintain the airtight from the reactor inlet 11 to the reactant reservoir 16 '.

That is, according to the present invention, a screw 15 connected to an electric motor is mounted in the reaction body surrounded by the heater 14, and the raw material inlet 11 and the discharge of the reactant material for supplying the raw material into the reaction body are installed. In the reactor in which the reactant discharge port 16 is installed, the vacuum control means for controlling the degree of vacuum while maintaining the airtightness from the raw material inlet 11 to the reactant reservoir 16 'is provided. And an anisotropic pitch production apparatus.

The present invention also provides a method for producing an anisotropic pitch using the apparatus for producing an anisotropic pitch described above.

Anisotropic pitches require pretreatment to remove primary quinoline insolubles and other foreign matter before injecting the pitch, a raw material, into the reactor.

Primary quinoline insolubles and other foreign matters cannot be converted to anisotropic pitches, which are mesophase pitches, by heat treatment.If they remain in anisotropic pitches, they cause single yarns during melt spinning for use as raw materials such as carbon fibers. It is essential to remove these materials beforehand because they cause cracks and cause deterioration of the final carbon fiber properties.

In the anisotropic pitch manufacturing method of the present invention, after melt the pre-treated raw pitch, it is injected into the reactor 10 heated to 330-450 ℃ at a rate of 0.002-0.1 cm 3 / min 2, wherein the degree of vacuum inside the reactor While maintaining the 30-380 mmHg, the screw 15 inside the reactor 10 is rotated at a rotational speed of 2 rpm at the lower limit and an upper limit [0.06 rpm / cm 2 × reaction surface area] to stir the injected raw material pitch to discharge the reactants. It is characterized by.

In the present invention, the reason for limiting the internal temperature of the reactor, that is, the reaction temperature to 330-450 ° C. is that when the reaction temperature is 330 ° C. or less, it is difficult to effectively remove volatile components in a short time even if the reaction surface area is high or the vacuum degree is high. It is difficult to manufacture an anisotropic pitch of good quality because it requires a long time for the reaction, and if it is above 450 ° C, coke is formed due to rapid pyrolysis even if the vacuum degree is low. It is because it is manufactured in a product close to coke which cannot be used for a purpose.

In the present invention, the lower limit of the rotational speed of the screw is 2 rpm and the upper limit is the rotational speed obtained by the rotational speed per reaction surface area of 0.06 rpm / cm 2, that is, (0.06 rpm / cm 2 × reaction surface area). If the speed is 2rpm or less, since the pitch of the raw material does not adhere to the reactant by screw rotation well on the surface of the screw, the reaction does not occur effectively because it stays in the lower part of the reactor, and the raw material pitch attached to the upper part of the paddle becomes thinly attached. Depending on the conditions, there is a possibility of coking, and if the proper rotational speed of the reaction surface screw is 0.06rpm / ㎠ or more, the reactant is discharged too fast, so the reaction time is short. Because of this.

In addition, in the present invention, the feed rate of the raw material pitch is limited to 0.002-0.1 cm 3 / min 2 (at a feed rate per reaction surface area) when the feed rate is 0.002 cm 3 / min 2 or less. It is highly likely to coke due to the part that is not easily transferred and attached.In case of 0.1cm3 / min2 or more, the reaction time is very short even if the vacuum is kept high and is discharged before the reaction temperature of the reaction body is raised. This is because the ratio of occupying the inner space of the reaction body becomes high, and thus it is difficult to effectively remove volatile components.

In addition, in the present invention, the reason for limiting the vacuum degree to 30-380 mmHg is that, when the pressure is maintained at a pressure lower than 30 mmHg, the lowering of the low molecular weight component occurs, causing the reaction to proceed too quickly to adhere to the reaction paddle. This may cause coking, and the reactant may not be discharged well through the reactant outlet, but may be discharged to the volatile outlet. If it is maintained at a pressure higher than 380 mmH and the pressure is maintained, the reaction may not proceed efficiently. Because it does not.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

5 millimeters of feed paddles with 25mm rotation diameter and 15mm width-7 tanks with mixed feed paddles with 25mm rotation diameter and 12.5mm width-10 tanks with mixed feed paddles with 25mm rotation diameter and 12.5mm width-7 tanks with same feed blend Combinations were made in sequence, keeping the reactor temperature at 420 ° C and rotating at a rate of 5 revolutions per minute with the length of the fuselage and the second row paddles being 425 mm, the sum of the surface areas being approximately 505 cm 2, and the effective reaction volume being approximately 169 cm 3. While feeding the raw material pitch preheated to about 300 ℃ at a rate of 10 kPa per minute. The vacuum degree at this time maintained 500 mmHg. The raw material pitch used was a pitch of Malta with a purified softening point of 121 ° C. The residence time of the pitch in the reactor was about 5 minutes. As a result, an isotropic pitch of 148 ° C. was produced, and the residue yield was 85% by weight.

Example 2

In a reactor of the same combination as in Example 1, the raw material pitch preheated to about 300 ° C. was introduced at a rate of 5 kW per minute while maintaining the temperature at 430 ° C. and rotating at a rate of 5 revolutions per minute, wherein the vacuum degree was 200 mmHg. Maintained. The pitch of the raw material was the same as in Example 1, and the residence time of the pitch in the reactor was about 5 minutes. As a result, an anisotropic pitch having a mesophase content of about 2 vol% at a softening point of 168 ° C. was prepared, and the residue yield was 76% by weight.

Example 3

The raw material pitch preheated to about 300 ° C. was introduced at a rate of 5 kPa / min while maintaining the reactor temperature at 420 ° C. and rotating at a rate of 5 revolutions per minute under the paddle combination conditions of Example 1, wherein the vacuum degree was 15 mmHg. Maintained. The raw material pitch used the same thing as Example 1. As a result, the prepared pitch was discharged to a trap through the low molecular weight material outlet in addition to the reactant outlet, and continuous reaction was impossible, and a partial anisotropic pitch having a non-softening point was produced.

Example 4

Under the same conditions as in Example 3, only the vacuum degree was maintained at 80 mmHg and reacted. As a result, an anisotropic pitch having a uniform mesophase content and distribution of about 10 vol% at a softening point of 180 ° C. having a structure as shown in FIG. 3 (a) was prepared, and the residue yield was 69% by weight.

Example 5

The reactors having the paddle combinations of Example 1 were connected in series so that the reactor and the row two screws had a length of 510 mm and a surface area of about 1010 cm 2 and an effective reaction volume of about 338 cm 3 respectively. The feed pitch preheated to about 300 ° C. was introduced at a rate of 5 kPa / min while rotating at a rate of 5 revolutions per minute. At this time, the vacuum degree of each reactor was maintained at 50 mmHg. The raw material pitch was used in the same manner as in Example 1, and the residence time of the pitch in the reactor was about 10 minutes in total. As a result, an anisotropic pitch containing a mesophase content of about 80% by volume and a uniform distribution of liquid crystal globules having a tissue structure as shown in FIG. 3 (b) was prepared, and the residue yield was 57% by weight.

Claims (1)

After melting the pretreated raw material pitch, it is injected into the reactor 10 heated to 330-450 ° C. at a rate of 0.002-0.1 cm 3 / min 2, at which time the vacuum inside the reactor is 30-380 mmHg, The internal screw 15 is rotated at a rotational speed with a lower limit of 2 rpm and an upper limit of [0.06 rpm / cm 2 × reaction surface area] to stir the injected raw material pitch to discharge the reactants.