JPH0222794B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a carbon material raw material. Specifically, the present invention has BI > 95% by weight, QI > 80% by weight,
The present invention relates to a method for producing a carbon material raw material that has a characteristic value of VM4 to 15% by weight and can be molded and fired into a high-density carbon material without using a binder. Carbon materials are good conductors of electricity and heat, are stable up to high temperatures in non-oxidizing atmospheres, have high hot strength, are resistant to attack by acids, alkalis, and other chemicals, and are easy to machine. It has excellent features such as excellent self-lubricating properties, a small absorption area for thermal neutrons, and excellent moderation ability, making it suitable for use in steelmaking electrodes, electrical brushes, nuclear reactor materials, and mechanical materials. It is widely used as. These carbon materials are generally produced by mixing aggregate coke and a binder, molding, firing or graphitizing the mixture. However, mixing aggregate coke and binder is a complicated work process, which not only creates a bad working environment, but also the aggregate coke itself is porous, and the coal tar pitch and synthetic resins used for the binder are difficult to calcinate. The density of the carbon material that can be manufactured to generate a large amount of pores is
The bending strength is about 1.5 to 1.7 g/ ^cm3 , and the bending strength is at most
500Kg/ ^cm2 , and in addition, due to the anisotropy of the aggregate coke, the carbon materials produced also have anisotropy in their properties, making it possible to create high-density, high-strength, and isotropic carbon materials. The drawback was that it was difficult to manufacture. However, with the development of industry, demands for the quality of carbon materials have increased, and various needs are rapidly increasing, centering on isotropic, high-density, and high-strength carbon materials. In view of the drawbacks of the conventional carbon material manufacturing method, the drawbacks of the carbon material itself, and the demands for quality in the market, the inventors of the present application have conducted intensive research and have developed a method for using a binder, unlike the conventional method. High density and previously unrecognized
We have succeeded in developing a new method for producing raw carbon materials that can stably produce carbon materials with various properties, including high-strength isotropic carbon materials. The method for producing a carbon material raw material of the present invention consists of four main steps: solvent extraction of a thermally treated coal tar pitch product, supersolvent extraction, and calcination of an excess residue product and classification of the calcined product. Of these, heat treatment
The three steps of solvent extraction, percolation, and calcination are a combination of steps that are essential for stably obtaining a carbon material without using a binder. The classification process serves to improve the quality of the carbon material raw material by dividing the calcined product obtained in the calcination process into fine particle components and coarse particle components in arbitrary proportions. The process will be explained in more detail below. First, coal tar pitch is heat treated at 350 to 500°C according to conventional methods. At this time, as the heat treatment temperature increases, a quinoline-insoluble component (hereinafter referred to as QI component) consisting of a polymer component is generated from the pitch. Normally, the QI component generated by this heat treatment starts to be generated at around the heat treatment temperature of 350℃, and as the temperature rises, the QI component increases until about 600℃.
Reach 100%. The QI components (generally referred to as mesophases) have a structure similar to graphite, unlike the QI components originally contained in some pitches (generally referred to as free carbon), and are also referred to as graphite precursors. However, although it itself has caking and sintering properties, its strength is weak and it is difficult to create a stable large-sized carbon material without using a binder. In the subsequent solvent extraction and passing steps, the QI component is extracted and separated from the heat-treated pitch together with the β component (benzene-insoluble, quinoline-soluble component) in the heat-treated pitch. The β component is composed of components with a slightly lower molecular weight than the QI component, but unlike the QI component, it has extremely strong caking properties and plays a role as a binder in the process of manufacturing carbon materials. However, since the β component generates a large amount of volatile matter during the firing process for manufacturing the carbon material, if left as it is, it will cause cracks and blisters to occur in the carbon material during the firing and graphitization stages. On the other hand, the BS component (benzene-soluble component) in the heat-treated pitcher not only has inferior caking properties compared to the β component, but also has a much higher volatile content than the β component. Therefore, it is more likely than the β component to cause cracking or blistering of the carbon material, and it is desirable to remove it as much as possible in the solvent extraction process. Normally, when heat-treated pitch is subjected to solvent extraction and filtration, it is necessary to use a large amount and several types of solvents in order to remove BS components. In addition, if the extracted residue is used as a carbon material raw material as it is, or by drying under normal pressure below 250℃ or vacuum, it is possible to remove the BS component, but the β component does not volatilize and remains as it is. . However, if a large amount of the β component remains, the carbon material raw material formed during the firing and graphitization stage will crack or bulge, so there is a limit to its remaining amount. Since the solvent extraction and passing steps in the present invention are combined with the calcination process, only one type of solvent is used, and a very simple process of just two extraction steps, primary and secondary, is sufficient. . Also, since the solvent used in the secondary extraction can be used again in the primary extraction, the amount of solvent used is usually 3 to 8 times the weight of the heat-treated pitch, depending on the characteristics of the required carbon material. It is enough. Also QI
Since it is possible to greatly increase the amount of β component entrained in the component, not only does the yield of carbon material raw material in coal tar pitch improve, but it also eliminates the need to remove most of β as in the conventional method. The solvents that can be used can be selected from a wide range, including oil in tar, light oil, toluene, and benzene. According to the method of the present invention, in order to produce a carbon material raw material that can stably provide a carbon material without using a binder, it is necessary to carry out solvent extraction and benzene extraction in the pass process. It is necessary to obtain an extracted residue having characteristic values such that benzene insoluble content BI > 90% by weight and quinoline insoluble content QI < 95% by weight when quinoline extraction is performed. Furthermore, the extraction/excess residue can be easily achieved by the simple method described above.
If the BI weight% of the extraction/excess residue is lower than 90% by weight, the residual amount of the extraction solvent and the residual amount of BS components in the heat treatment pitch are large, so the excess residue has a strong stickiness and is difficult to handle during the calcination process. It is necessary that BI>90% by weight because handling becomes difficult and a large amount of BS components with poor caking properties remain. Also, if QI is 95% by weight or more,
Since the remaining amount of the β component, which is a viscosity component, is small, it is difficult to stably obtain a large carbon material without using a binder. In the next step, the extracted residue is calcined under an inert atmosphere. The calcination treatment is carried out at 250-500°C. The purpose of this calcination treatment is to extract the cracks and blisters that occur during calcination and graphitization of the formed carbon material raw material, remove residual solvent in the excess residue, and remove trace amounts of low volatile matter in the heat treatment pitch. In addition to solvent extraction and extraction, residual β
This involves performing a thermal polymerization reaction to convert some of the components into QI. The QI component transferred from the β component due to the thermal polymerization reaction during the calcination treatment does not become mesophase under the condition of BI > 90% by weight, unlike the QI component generated when pitch is heat-treated at 250 to 500°C. As microparticles with the properties of It can act as a binder. In this way, the calcination treatment makes it possible to remove the low volatile content that causes cracks and blisters during calcination and graphitization of the shaped carbon material raw material, without losing the caking properties of the β component. As a result, a carbon material can be stably obtained without using a binder. The required calcination temperature is selected within the range of 250°C to 500°C. This is because the QI reaction of the β component is difficult to proceed at temperatures below 250°C, making it difficult to sufficiently remove low volatile components. while 500
This is because at temperatures above 0.degree. C., the QI component loses its caking properties more rapidly than the beta component, making it impossible to obtain a carbon material without using a binder. The characteristic values of the calcined product are BI > 95% by weight, QI > 80% by weight, 15% by weight > VM > 4% by weight, and 250% by weight depending on the characteristic values of solvent extraction and excess residue. A suitable calcination temperature is selected within the range of 500°C to 500°C to obtain a calcined product having the specified characteristic values. B.I.
If it does not exceed 95% by weight, cracks and blisters will occur during firing and graphitization of the molded carbon material raw material due to the low volatile content due to the BS component having poor caking properties. Also QI
% is less than 80% by weight, cracks and blisters occur mainly due to the influence of volatile matter caused by the β component. On the other hand, VM (volatile components when heated at 800°C for 7 minutes) mainly indicates volatile components caused by both the BS component and the β component, and when this value exceeds 15% by weight, firing graphitization occurs. Cracking and blistering occur. or
When VM is 4% by weight or less, the QI reaction of the β component progresses too much and the caking property deteriorates, making it impossible to obtain a carbon material without using a binder. Furthermore, we have found that a continuous external heating rotary kiln is optimal for carrying out this calcination process industrially. In our study, according to the rotary kiln,
If the characteristic value BI% of solvent extraction/excess residue exceeds 90% by weight, the screw feeder will uniformly transfer the solvent extraction/residue, charge it into the kiln, and heat it in the kiln. The movement of the materials proceeded smoothly, and it was possible to continuously obtain calcined products of stable quality. The calcined product can be provided with carbon material as is without the use of a binder. Moreover, the properties of graphitized carbon materials can be determined by selecting conditions such as the properties of raw material pits, heat treatment temperature, solvent extraction, properties of excess residue, and calcination temperature when producing calcined products. 1.5g/cm ³ , bending strength
From carbon material with relatively low density of ^about 300Kg/cm2,
It is possible to produce various isotropic carbon materials with a wide range of properties, including carbon materials with a density of 20 g/cm ³ and bending strength of 1000 Kg/cm ² , which were previously unrecognizable. . Further, the electrical resistivity can also have any value in the range of 900 μΩcm to 4000 μΩcm. In general, when the QI component originally contained in the raw material pitch increases, it tends to become a high-density, high-strength carbon material with a large electrical resistivity.Also, when the QI generated during heat treatment increases, it has a relatively low density, low strength, and a low electrical resistivity. It tends to become a small carbon material. In addition, if the β component in the residual residue increases due to solvent extraction, or if the calcination temperature is lowered to increase the VM (%) and β component of the calcined product, it tends to become a high-density, high-strength carbon material. Cracks and blisters are more likely to occur during the firing and graphitization stages of the raw materials. Furthermore, if the molding pressure of the carbon material raw material is also increased, the carbon material tends to have high density and high strength, but conversely, cracks and blisters are more likely to occur during the fired graphitization stage. Therefore, by combining the above conditions, it is possible to stably obtain a carbon material having any of the above-mentioned values. Moreover, as a result of further studies, we were able to classify the calcined product into a coarse component, which is mainly composed of relatively coarse grains, and a fine component, which is mainly composed of relatively fine particles. It was discovered that this material can be used as a raw material for carbon materials that can be used to produce carbon materials with specific properties. The properties of carbon materials obtained from coarse-grained and fine-grained components differ depending on the characteristics of the calcined product or the yield of each component during classification, but in general, compared to carbon materials from calcined products, The carbon material obtained from the coarse particle side component is a carbon material with relatively low density, low strength, and high electrical resistivity, and the carbon material obtained from the fine powder side component is a carbon material with high density, high strength, and low electrical resistivity. becomes. Therefore, if this classification process is performed on a calcined product, a relatively low density carbon material with a density of 1.4 g/cm ³ and a bending strength of 200 Kg/cm ² can be converted to a carbon material with a density of 2.05 g/cm ³ and a bending strength of 1300 Kg/cm 2 .
It is possible to produce various graphitized isotropic carbon materials with a wider range of properties, including carbon materials with unprecedented ultra-high density and high strength of Kg/cm ² .
Furthermore, the electrical resistivity can also have any value in the range of 800 μΩcm to 5000 μΩcm. Industrially, it is optimal to use a wind centrifugal classifier to classify the calcined product. The advantage of using this classifier for classifying calcined products is that it can industrially easily classify calcined products with various particle sizes into coarse particle components and fine particle components in various ratios, and as a result of our research, The ash contained in nuts or solvents and remaining in the calcined product during manufacturing is concentrated into the coarse particle component through classification, and as a result, the fine particle component becomes a high-purity carbon material raw material with extremely low ash content. I found out. This is because the wind centrifugal classifier classifies raw particles based on the difference in particle size and specific gravity, and fine Al,
This is because ash such as Si and Fe has a higher specific gravity than carbon, so it easily migrates to the coarse particle side components. In addition to the above-mentioned method for producing new carbon material raw materials, we have conducted further intensive research and found that the calcined or classified products manufactured using this method are forcedly oxidized in air at 100°C to 300°C. The inventors also discovered that a carbon material with extremely high electrical resistivity can be obtained by processing without using a binder. According to this method, a graphitized isotropic carbon material having an electrical resistivity of up to 8000 μΩ-cm can be produced without using a binder. Normally, calcined or classified products are extremely stable at room temperature, but unlike ordinary aggregate coke, they are chemically active, so they rapidly absorb oxygen from the air when the temperature exceeds 100°C. This oxidized product provides a carbon material without the use of a binder, but the graphitized carbon material has a high electrical resistivity. On the other hand, if the oxidation treatment is carried out at a temperature exceeding 300°C, both the calcined product and the classified product lose their caking properties, making it impossible to obtain a carbon material without using a binder. Therefore, the oxidation treatment temperature in air is 100°C to 300°C.
It is necessary to carry out the test at a temperature of The oxidation treatment can be achieved by forcibly blowing air into the calcined or classified product while heating and stirring it. As described above, the method for producing a carbon material raw material of the present invention can provide a new carbon material without using a binder, which was not possible in the prior art, and by changing the production conditions, It has been shown that carbon materials with an extremely wide range of properties can be industrially produced in an extremely stable manner.
In particular, it is possible to produce carbon materials with ultra-high density and high strength that could not be obtained using conventional techniques. The present invention is not limited to coal tar pitch as a raw material, but can also be applied to petroleum pitch or bitumen obtained by liquefying and deashing coal. Specific examples will be explained below. <Example 1> Softening point (R, B method): 80°C, BI: 19% by weight,
QI: 4% by weight coal tar pitch was heat treated at a temperature of 445° C. for 10 minutes using a heat treatment tank to obtain heat treated pitch. The characteristic values of this heat-treated pitch are BI: 50.6% by weight,
QI: 28.7% by weight. For 100 parts by weight of this heat-treated pitch, 600 parts by weight of oil in tar (boiling point range 140 DEG C. to 270 DEG C.) was used to carry out two overextraction operations, a primary and a secondary extraction. The temperature of the primary and secondary extractions at this time was 120°C, and the extraction time was 1 hour. In addition, pressurization was carried out.
The characteristic values of the extracted residue at this time were BI: 96.3% by weight and QI: 78.2% by weight. The solvent extracted residue was subsequently calcined in an externally heated rotary kiln at a temperature of 340° C. under a N ₂ atmosphere. The characteristic values of the obtained calcined product are
BI: 98.0% by weight, QI: 89.5% by weight, and VM: 8.5% by weight. The calcined product was molded without using a binder at a pressure of 800Kg/cm ² and a molding size of 100φ
Forming is carried out at 100hm/m, followed by firing and firing according to the usual method.
Graphitization was carried out. The graphitization temperature was 2700°C. The physical properties of the graphitized block at this time are shown in Table 1. The calcined product was further divided into coarse particle components and fine particle components using a wind centrifugal classifier. The yield of each component at this time was: coarse particle component: 15% by weight, fine particle component: 85% by weight. The characteristic values of each component are shown in Table-2. These components were molded, fired, and graphitized under the same conditions as for the calcined product without using a binder, and the physical properties of the graphite blocks are shown in Table 1. The graphitization temperature was 2700°C, the same as in the case of calcined products.
As seen in the results in Table 1, both the calcined product and the fine particle component gave carbon materials with high density and high strength. Furthermore, the fine particle component obtained by classification provided a carbon material with increased density and strength compared to the calcined product. On the other hand, the carbon material obtained from the coarse particle component had a lower density and higher specific resistance than the carbon material obtained from the calcined product and the fine particle component. As shown in Table 2, the ash content was concentrated into coarse particle components by classification, and the fine particle components became highly pure carbon material raw materials.

【table】

[Table] <Example 2> Solvent extraction and excess residue in Example 1 were treated with N ₂
A continuous rotary kiln under atmospheric conditions allows 360
Calcining treatment was carried out at ℃. The characteristic values of the obtained calcined product are BI: 98.5% by weight, QI: 90.8% by weight, VM: 8.0
It was in weight%. The calcined product was molded as is without using a binder at a molding pressure of 1000 kg/cm ² and a molding size of 100φ×
Molding was carried out at 100 hm/m, followed by firing and graphitization according to the usual method. On the other hand, the calcined product was divided into coarse particle components and fine particle components using a wind centrifugal classifier. The yield of each component at this time is: coarse particle component: 13% by weight;
Fine particle component: 87% by weight. This component was shaped, fired, and graphitized under the same conditions as the calcined product without using a binder. The graphitization temperature was 2700°C in all cases. Table 3 shows the physical properties of the graphite blocks obtained from the calcined product, coarse particle component, and fine particle component. The calcined product and fine particle component provided a carbon material with high density and high strength. In particular, the fine particle component has a bending strength of 1300 kg/cm ² , making it an ultra-high strength carbon material. On the other hand, the coarse particle component became a carbon material with a somewhat lower density and higher resistivity than the calcined product and the fine particle component.

[Table] <Example 3> Coal tar pitch having the same properties as in Example 1 was heat treated in an autoclave at a temperature of 460° C. for 30 minutes to obtain heat treated pitch. The characteristic values of this heat-treated pitch were BI: 69.8% by weight and QI: 51.7% by weight. The heat-treated pitch was subjected to solvent extraction and filtration according to Example 1. The characteristic values of solvent extraction/excess residue at this time are BI: 95.2% by weight, QI: 81.1% by weight
It was hot. The solvent-extracted residue was then calcined at a temperature of 360° C. in a N ₂ atmosphere using a continuous rotary kiln. The characteristic values of the calcined product after calcination were BI: 98.0% by weight, QI: 89.0% by weight, and VM 7.7% by weight. After the calcined product was finely pulverized, it was calcined and graphitized using a conventional method at a molding pressure of 800 Kg/cm ² and a molding size of 100φ×100 hm/m without using a binder. On the other hand, the calcined product was divided into coarse particle components and fine particle components using a wind centrifugal classifier. The yield of each component at this time was 26% by weight for the coarse particle component and 74% by weight for the fine particle component. Each of these components was shaped and calcined to graphitize under the same conditions as for the calcined product without using a binder. The graphitization temperature was 2700°C in all cases. Table 4 shows the physical properties of the graphite blocks obtained from the calcined product, coarse particle component, and fine particle component. The calcined product and fine particle component became a carbon material with high density, high strength, and low resistivity.

[Table] <Example 4> SP (R&B method): 80°C, BI: 34.0% by weight, QI:
Coal tar pitch of 18.1% by weight was heat treated in an autoclave at a temperature of 440°C for 10 minutes to obtain heat treated pitch. The characteristic values of this heat treated pitch are
BI: 48.5% by weight, QI: 26.4% by weight. This heat-treated pitch was subjected to solvent extraction and filtration according to the method of Example 1. The characteristic values of the solvent-extracted residue were BI: 94.2% by weight and QI: 76.5% by weight. Thereafter, the solvent-extracted residue was calcined in a continuous rotary kiln at a temperature of 400° C. in an N ₂ atmosphere. The characteristic values of the calcined product after calcination were BI: 99.0% by weight, QI: 97.5% by weight, and VM: 6.2% by weight. The calcined product was molded at a pressure of 600Kg/cm ² ,
Molding was performed without using a binder with a molding size of 100 φ x 150 hm/m, and firing and graphitization were performed according to a conventional method. On the other hand, the calcined product was divided into coarse particle components and fine particle components using a wind centrifugal classifier. The yield of each component at this time was 19% by weight for the coarse particle component and 81% by weight for the fine particle component. Each of these components is mixed under the same conditions as for calcined products without using a binder.
Shaping and firing graphitization are performed. The graphitization temperature was 2700°C. Table 5 shows the physical properties of the graphite blocks obtained from the calcined product, coarse particle component, and fine particle component. Each graphite block has low density, low strength,
It has become a carbon material with high resistivity.

[Table] <Example 5> While stirring the calcined product in Example 1 in a kneader, air was forcibly blown into the calcined product in a kneader to give 100%
℃, 200℃, and 300℃ to produce three types of oxidized and calcined products. When we measured the oxygen content of calcined products treated at each temperature, we found that as the treatment temperature rose, the oxygen content increased.
Oxidation was progressing. (Figure 1) The oxidized and calcined product was molded at a pressure of 800 kg/cm ² and a molded size of 100φ× without using a binder.
Forming is carried out at 100hm/m, then fired and fired using the usual method.
Graphitization was performed to obtain a graphite block. The graphitization temperature was 2700°C. Table 6 shows the physical properties of the graphite blocks obtained from each oxidized and calcined product in comparison with those of the non-oxidized and calcined product. As the oxidation treatment temperature increases, the specific resistance of carbon materials increases, especially at 300℃.
The oxidized carbon material had a high resistivity of 10,000μΩ-cm. In addition, if the oxidation treatment temperature exceeds 300℃,
The calcined product lost its caking properties and it was not possible to obtain a graphite block without using a binder.

【table】 [Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the oxidation treatment temperature and oxygen content of the calcined product in Example 5. The horizontal axis shows the oxidation treatment temperature (°C), and the vertical axis shows the oxygen content (%).

Claims (1)

[Claims] 1 Coal tar pitch is heat-treated at a temperature of 350 to 600°C, and the resulting heat-treated product is extracted with a solvent.
An overextracted residue with BI (benzene insolubles) > 90% by weight and QI (quinoline insolubles) < 95% by weight was obtained, and the residue was calcined in an inert atmosphere at a temperature of 250-500 °C to produce BI. >95% by weight, QI >80% by weight, VM (volatile content)
A method for producing a carbon material raw material comprising obtaining a calcined product of 4 to 15% by weight. 2 Heat-treat coal tar pitch at a temperature of 350 to 600°C, extract the resulting heat-treated product with a solvent, and
Obtain an overextraction residue with BI>90% by weight and QI<95% by weight, and calcin the residue at a temperature of 250-500°C in an inert atmosphere to produce BI>95% by weight and QI>80% by weight. ,
A method for producing a carbon material raw material, which comprises obtaining a calcined product having a VM of 4 to 15% by weight, and classifying the calcined product to a desired particle size. 3 Heat-treat coal tar pitch at a temperature of 350 to 600℃, extract the resulting heat-treated product with a solvent, and
Obtain an overextraction residue with BI>90% by weight and QI<95% by weight, and calcin the residue at a temperature of 250-500°C in an inert atmosphere to produce BI>95% by weight and QI>80% by weight. ,
A calcined product with a VM of 4 to 15% by weight is obtained, and the calcined product or a classified product obtained by classifying the power-calcined product is heated in air.
A method for producing a carbon material raw material comprising oxidation treatment at a temperature of 100 to 300°C. 4 Heat-treat coal tar pitch at a temperature of 350 to 600°C, extract the resulting heat-treated product with a solvent, and
Obtain an overextraction residue with BI>90% by weight and QI<95% by weight, and calcin the residue at a temperature of 250-500°C in an inert atmosphere to produce BI>95% by weight and QI>80% by weight. ,
A calcined product with a VM of 4 to 15% by weight is obtained, and this is classified into a coarse grain component rich in coarse grains and a fine grain component rich in fine grains. After oxidation treatment at a temperature of 300℃,
A method of producing carbon material comprising forming, firing or graphitizing.