JPS602352B2 - Production method of Primesoface carbonaceous material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing premethophase carbonaceous material useful as an intermediate for producing carbon fibers.

More specifically, the present invention proposes that premethoface carbonaceous material, which is an intermediate in producing carbon fibers from pitches,
Up until now, it has been manufactured by heat treatment under reduced pressure.
The present invention relates to an improved method for manufacturing by tempering the sword under normal pressure. Carbon fiber has insulation, heat resistance,
It is widely used in heat insulating materials, sealing materials, electromechanical parts, structural members, friction materials, carbon electrodes, etc. due to its excellent chemical resistance, rigidity, conductivity, and light weight.

Conventionally, carbon fibers have been produced by firing fibers such as acrylonitrile or cellulose, but these raw materials have the drawbacks of high cost and low carbonization yield.

On the other hand, various pitches that can be obtained in large quantities are by-products of the coal and petroleum industries, and methods have been proposed to use them as raw materials to produce carbon fibers, but they are difficult to spin due to their softening point, viscosity, etc. However, there is a point where the quality of the obtained carbon fiber is low, and the reality is that there are still many problems to be solved before it can be implemented industrially.

In order to solve these problems, a method using a pitch-like substance obtained by hydrogenating or heat treating a specific condensed polycyclic aromatic compound (Tsubaki Publication No. 45-28013,
Samurai Ko Sho 49-8 Wikiwaki Publication), petroleum tar and pitch were subjected to a first heat treatment in the presence of a Lewis acid catalyst, and then the catalyst was removed and a second heat treatment was performed. The method used (Japanese Patent Application Laid-open No. 7533), the method of forming a mesoface pitch with a predetermined final soface content under reduced pressure, and producing carbon fiber using this as a raw material (Japanese Patent Application Laid-Open No.
Methods using mesophase pitch having a specific composition and specific properties (Samurai Seki Akihiroichi No. 55625, U.S. Patent No. 3787 No. 1 specification), etc. However, even with these methods, it is not possible to obtain carbon fibers with properties comparable to those made from acrylonitrile, so to date, high-performance grade carbon fibers have been manufactured from pitch-like materials. No practical method was known.

Under these circumstances, the inventors of the present invention have conducted extensive research into a method for producing carbon fibers of excellent quality using pitches as raw materials, and have first achieved optical differences through carbonization treatment. We proposed a method for producing carbon fibers via a new optically isomergolic pitch-like material that can be converted into an orthotropic mesophase carbonaceous substance, that is, a pre-mesophase carbonaceous substance (
Mochikai Akihan-18421 Publication).

In this case, the primesophase carbonaceous material is treated in the first step, which consists of treatment of pitch with tetrahydroquinoline alone, treatment with quinoline and hydrogen in the presence of a catalyst, or treatment with aromatic hydrocarbon such as naphthalene and hydrogen. It was manufactured through a second process consisting of reduced pressure heat treatment, but
Since the reduced-pressure heat treatment step is accompanied by many difficulties when carried out industrially in terms of equipment and operation, there has been a desire to improve the process so that it can be carried out under normal pressure. As a result of further research into a method in which the second step in the production of the above-mentioned brimesophase carbonaceous material can be carried out under normal pressure, the present inventors have determined that the processing conditions for the first step and the processing conditions for the second step have been determined. The inventors have discovered that if they are appropriately selected and combined, the desired premethophase carbonaceous material can be obtained even if the second step is carried out under normal pressure, and based on this knowledge, the present invention has been accomplished.

That is, in the present invention, pitches are heated at 340 to 500°C, preferably at 380 to 470°C, in the presence of tetrahydroquinoline.
After holding at a temperature of 0 to 60 minutes, remove solids and tetrahydroquinoline, raise the temperature to a temperature higher than 450 qo per day under normal pressure, and then lower to 400 to 430 qo,
The purpose of the present invention is to provide a method for producing optically isomergolic Primeso-based carbonaceous material, which is characterized by maintaining the temperature at this temperature for 15 to 180 minutes.

The pitches used as raw materials in the method of the present invention include coal tar, coal tar pitch, coal-based heavy oils such as coal liquefied products, residual oils from atmospheric distillation of petroleum, residual oils from vacuum distillation, and those created by heat treatment of these residual oils. Petroleum-based heavy oils such as raw tar, pitch, and oil sand bits can be used, but coal-based oils are somewhat advantageous in that subsequent grades can be easily formed.

In the treatment with tetrahydroquinoline, which is the first step of the method of the present invention, 30 to 20 parts by weight of tetrahydroquinoline are added per 10 parts by weight of pitches, and the total temperature is 340 to 500 qo, preferably 0 to 470 qo. This is done by heating for ~60 minutes.

The tetrahydroquinoline in this case does not necessarily have to be a pure product; a mixture of tetrahydroquinoline and quinoline may be used, or quinoline and hydrogen may be used together in the presence of a catalyst to convert tetrahydroquinoline on the spot. It may be generated. When quinoline and hydrogen are used together, for example, 30 to 10 parts by weight of quinoline and 5 to 1 part by weight of catalyst are added per 10 part by weight of pitch, and the hydrogen pressure is 50 to 20 parts by weight.
Preferably, it is carried out under 0k9' carp conditions. As the catalyst in this case, cobalt-molybdenum-based and iron oxide-based catalysts are suitable. Moreover, a mixture of quinoline and tetrahydroquinoline can also be used instead of the above-mentioned quinoline alone. The product thus treated is passed through a sieve and distilled to remove solids, tetrahydroquinoline, and other substances, and then sent to the second step. In the second step of the method of the present invention, the product of the first step is heated to a temperature higher than 450 oo, preferably around 480 qo, and then heated to a temperature of 400 to 480 qo.
This is done by lowering the temperature to 43,000 °C and holding at this temperature for 15-180 minutes.

If too high a temperature is used as the initial heating temperature in this case, carbonization will progress and the stability will be lost, so it is desirable to select the temperature within a range not exceeding 500°C. Once this temperature is reached, it is immediately forced or naturally cooled down to a temperature of 400 to 430, and maintained for a predetermined period of time. It is necessary to select this holding time within the range of 15 to 180 minutes. Furthermore, in order to facilitate the removal of low boiling point components in the pitch during the second step, an inert gas such as nitrogen gas or water vapor may be blown into the pitch.

The thus obtained primesoface carbon usually has a softening point of 300 qo or less, a fixed carbon content of 87% or more, and is soluble in quinoline. On the other hand, it is also possible to contain mesophase, which is insoluble in quinoline and is more carbonized than primesophase in the second step. The amount of mesophase can be freely changed depending on the processing conditions in the second step. In the method of the present invention, in order to form the desired pre-mesophase carbonaceous material, two steps are required as described above. This is to remove low molecular weight components in the second step.

In addition, in the second step, the product of the first step is once
Although treatment at 50° C. or higher is required, if this treatment is excluded and treatment is performed at 400 to 430° C., pitch with excellent paper thread properties cannot be obtained. If it is treated at a temperature of 450 oo or higher, crabs will come out and the number of components that can be removed will be 40
This is thought to be because if only 0 to 43 pi 0 are processed, they remain. When this pitch is graded, a low viscosity part like water and a hard part are separated, and the former cannot be made into a fiber, and even if the latter part becomes a fiber, the resulting fiber is The fiber diameter is uneven, making it look like a snake swallowing an egg, resulting in thread breakage and nozzle clogging. When the pre-mesophase carbonaceous substance obtained by the method of the present invention is observed under crossed Nicols using a reflective polarizing microscope, the mesophase, which is commonly used as the raw material pitch for conventional carbon fibers, has a pitch of 45° when the Nicols are rotated. While dark black and white states are repeated as a cycle,
This thing is always dark black and does not change.

From this, it can be seen that the above-mentioned pre-mesophase carbonaceous material is optically isotropic. The premethophase carbon fiber obtained by the method of the present invention can be made into excellent quality carbon fiber by spinning it, making it infusible, and carbonizing it.

This weaving yarn can be carried out according to conventionally known carbon fiber spinning methods such as melt extrusion spinning, deep D spinning, and blow spinning. For example, pre-methoface carbonaceous material with a diameter of 0
．． Place it in a grader with a nozzle of 1 to 0.8 sails, heat it to a temperature 50 to 140 degrees Celsius higher than its softening point by external heating, and use an inert gas such as nitrogen gas to 0.2 to 2 [ 9
This can be done by extruding the material with the pressure of 1/200 m/s and winding up the pitch emerging from the nozzle at a winding speed of 50 to 1,000 min. The treeability in this case is related to the purity of the pre-mesophase carbonaceous substance, and the amount of mesophase in it is 6.
% by weight or less, it can be wound at a high speed of 1000 weft/min or more, but if it contains more than that, continuous spinning is not possible unless the speed is lowered, and the yarn cannot be spun. Causes cuts. In this paper yarn, the amount of mesophase in the filament produced does not substantially change before and after spinning. Next, the infusibility treatment is carried out by placing the filament obtained as described above in an electric furnace, for example, and heating the filament in an air stream at a heating rate of 0.5 to 1 C'min to 250 to
This is done by heating to 35-0 and maintaining for 0-30 minutes. The filament thus twisted is then subjected to a carbonization treatment to convert the pre-mesophase carbonaceous material therein into mesophase.

This carbonization treatment is carried out, for example, in an inert gas flow such as nitrogen gas at a heating rate of 5 to 100 qC'min.
Heat to a temperature within the range of 1200°C and keep at this temperature for 10
This is done by holding for ~30 minutes. This treatment converts substantially all of the optically isotropic pre-mesophase carbonaceous material into optically anisotropic mesophase. In this way, the fibers obtained by carbonization at 1000qC have a diameter of 20mm or less and a tensile strength of 200 to 320k.
9/ Dislike, elongation rate 1.2-1.6% elastic modulus 10-15t/
The carbon fiber of the fence is obtained in a total yield of % or more based on the raw material.

According to the method of the present invention, there is an advantage that a brimesophase carbonaceous material having the same bushiness as that obtained by the conventional reduced pressure method can be produced with a simple operation.

Furthermore, in the second step, since the two-stage method uses a low temperature, it is easy to control the properties of the spinning pitch, and the sublimable components among the volatile components can be almost completely removed. has advantages. Hereinafter, the present invention will be explained in more detail by giving Examples.

Example 1 Coal tar pitch used as a raw material pitch had a quinoline insoluble content of 8 t%, a benzene insoluble content of 35.5 M%, and a fixed carbon content of 62. It has the properties of a fence t% and a softening point of 9 points.

Add 400 m of this pitch to a 2 quart autoclave and mix with 20 M of quinoline containing 30% tetrahydroquinoline.
Red mud (Fe2Q-containing 4
3.8%) was added.

Next, the initial pressure of hydrogen was set to 75×9/G of water, and the average overflow rate was adjusted to 2. The temperature was raised to 450 qo at yC'min and maintained at this temperature for 10 minutes. Immediately after the time elapsed, the autoclave was removed from the furnace and cooled to room temperature. This treated product was passed through a centrifugal precipitator to precipitate the solid matter, and then the upper light was sieved under reduced pressure using qualitative paper. The filtered supernatant liquid was distilled under reduced pressure (IQ Misaki Hg) to 290°C. This distillation residue was used as a raw material for the next step. Table 1 summarizes the amounts of fixed substances and distillation residue obtained when processing was carried out under various conditions in the same manner as above. Table 1 (1) The amount of solid matter is the value without the amount of red mud added as a catalyst.

100 pieces of the distilled residue pitch obtained by treating with tetrahydroquinoline at 450°C for 60 minutes as shown in Table 1 were placed in a 300' glass cylindrical container, placed on the top of a furnace preheated to 500°C, and placed at the top of a furnace previously heated to 500°C. It was preheated to 300°C.

This is to shorten the time required to reach the processing temperature as much as possible. A glass tube was placed in the tube until it reached the bottom, nitrogen gas was passed through the tube at a rate of about 2/min, and the tube was placed into the furnace while bubbling. After about 15 minutes, the temperature of the contents reached 480°C, so the container was removed from the oven and allowed to cool to room temperature. This operation was repeated several times, and the resulting pitch was used in the next experiment. The above pitch is 100 evenings to 300'
It was placed in a cylindrical container and heated to about 250°C.

Then, while blowing nitrogen gas for 2 minutes, the temperature was increased to 3℃/
Heating up to 420℃ at a heating rate of min.
It was held for 0-180 minutes. After the time had elapsed, the container was immediately taken out from the furnace and cooled to room temperature to obtain spinning pitch.
The yield and properties of this pitch are summarized in Table 2. Table 2 (1) Yields were based on the pitch obtained in the first step.

Paper yarns having pitches for paper yarns shown in Table 2 were prepared in the following manner. The paper yarn pitch was placed in a brass paper making machine with an inner diameter of 20 ribs and a length of 15 meters equipped with a nozzle with a diameter of 0.5 or 0.3 ribs for about 10 minutes, and the temperature of the pitch was softened by an external heater. It was heated to a temperature of 60 to 140 degrees above the point.

Next, from the upper part of the pitch, nitrogen gas is applied to the pitch by 0.1 to 1.
The filament spun out from the nozzle is extruded under pressure at 0k9/base (gauge pressure) and is then spun into a drum with a diameter of 30 meters.
000/min. For this paper yarn, if the winding speed is 1000'min and the diameter of the wound filament is about 10mm, the pitch temperature can be adjusted to about 80mm by changing the nozzle diameter and nitrogen gas pressure. and can vary over a wide range.
However, if the pitch has a softening point of 300°C or higher, the paper yarn temperature will be 400°C or higher. Care must be taken to keep the pitch at such a high temperature for a long time, as this may change the properties of the pitch. In any case, the pitch shown in Table 2 can be obtained by appropriately selecting the pitch temperature, nozzle diameter, and gas pressure at a winding speed of 1000 w/min.
It is easy to produce filaments with a diameter of about 1 sq. One end of the filament thus wound around the drum was cut off, and the east end of the filament, approximately 1 1000 mm in length, was collected.

A part of it is hung on a wire with a diameter of 1 rib and kept in the air from room temperature to 2.
The sample was heated to 00°C at a rate of 5°C/min, then raised to 300°C at a rate of 2°C/min, and held at this temperature for 18 minutes. This was heated to loo000 in a nitrogen gas stream at a heating rate of 25°C'min and held for 15 minutes to form carbon fibers. The physical properties of the carbon fiber thus obtained were measured in accordance with the provisions of JISR7601 "Carbon Fiber Testing Method". Physical property values are average values of 10 test pieces. In addition, the fiber diameter was measured using a scanning electron microscope. Some of the results are shown in Table 3. Table 3 No. As shown in Table 2, Pitch No. 1 contains almost no quinoline insoluble matter, and the presence of slight optically anisotropic spherules is recognized even by observation with a polarizing microscope.

Claims (1)

[Claims] 1 Pits in the presence of tetrahydroquinoline, 380
After holding at a temperature of ~500°C for a period of no more than 60 minutes,
After removing the tetrahydroquinoline, the temperature was once raised to a temperature higher than 450°C under normal pressure, and then lowered to 400 to 430°C,
A method for producing optically isotropic PRIMESOPHACE carbonaceous material, which comprises maintaining this temperature for 15 to 180 minutes.