JPS6235964B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a high quality carbonaceous molded body. Carbonaceous molded bodies such as graphite electrodes and carbon brushes are generally manufactured through processes such as mixing, molding, firing and, if necessary, graphitization, which usually takes a long period of 3 to 6 months to manufacture. Moreover, it has various drawbacks, such as clogging and porous formation during manufacturing, which reduces product yield. For example, to make products with relatively high bulk density and high strength, fine powder is generally mixed as carbonaceous aggregate, but in this case, the surface area of the aggregate becomes large, the amount of binder required increases, and Due to significant dimensional changes during heat treatments such as firing and graphitization, internal defects such as hair cracks are likely to occur. That is, since a large amount of binder such as coal tar pitch is blended, problems such as porosity and cracking occur due to the escape of volatile power during firing. In order to prevent this, it is necessary to reduce the firing temperature increase rate to, for example, 1 to 3° C./hr, and the current situation is that the production takes a long time. Furthermore, in order to obtain an isotropic carbonaceous material, large-scale equipment is currently required, and there are many process and cost problems. The present inventors have conducted research to find a method to improve the shortcomings of conventional methods and to produce homogeneous, strong, and isotropic carbonaceous molded bodies with few internal defects in a simple manner and in a short period of time. We have arrived at the present invention.
That is, the present invention is a high-density carbonaceous aggregate characterized in that carbonaceous aggregate and bituminous material are mixed, heated and stirred, then pressure-formed, and then fired and graphitized, or the firing step is omitted and the formed product is directly heat-treated in a graphitization furnace. This is a method for producing a strong carbonaceous molded body. What is important about this technology is that
Rather than mixing aggregate with binder pitch, which already has sufficient caking properties, coal tar, soft pitch, heavy petroleum oil, etc., which are precursors of binder pitch that do not have substantially caking properties, are mixed. By mixing with the aggregate and heat-treating it, the formation of a binder is effectively promoted on the surface or surrounding area of the aggregate for the first time during the heat treatment, and in addition to achieving extremely good dispersion with this method, stirring By carrying out the process in a liquid state, it is possible to obtain a much higher degree of dispersion than when mixing is carried out in ordinary carbon material production. The present invention will be explained in more detail below. The carbonaceous aggregates used in the present invention include various types of coke such as pitch coke, petroleum coke, and fluid coke, uncalcined raw coke that is an intermediate product thereof, natural graphite, carbon black, etc., but especially raw coke, Alternatively, if a mixed system of raw coke and other aggregates is used, the resulting carbonaceous molded product will not have anisotropy in physical properties even if it is molded using a normal uniaxial pressure molding machine. Oriented carbonaceous material can be obtained. There are no particular restrictions on the particle size of the carbonaceous aggregate, but in order to obtain higher strength, it is preferable that the entire amount passes through a 200 mesh sieve and the average particle size is 30 microns or less. In addition, the bituminous materials to be mixed with aggregate and heat treated include coal tar, soft pitch which is a precursor of coal tar pitch, and 5% quinoline insoluble content such as petroleum heavy oil.
Below, a bituminous material with a benzene insoluble content of 15% or less is used, preferably a bituminous material with a quinoline insoluble content of 3% or less and a benzene insoluble content of 12% or less. In the present invention, the blending ratio of bitumen to carbonaceous aggregate is 0.5 times or more and 5 times or less, preferably 1.5 times or more and 3 times or less, relative to 1 part carbonaceous aggregate.
Desirably less than twice that. If the ratio is less than 0.5 times, sufficient stirring during mixing and heating will not be performed, and sufficient quality will not be imparted to the final product. Moreover, if it is 5 times or more, cracks or foaming are likely to occur during heat treatment such as firing and graphitization of the molded body. Thermal modification conditions during mixing and heating are 350°C or higher and 500°C or lower, preferably 380°C or higher and 450°C or lower.
The heat treatment time varies depending on the atmosphere, pressure, temperature, etc., but is 0.5 to 40 hours. In addition, the pressure during heating is volatilized under pressure, reduced pressure, normal pressure reflux, or with a carrier gas such as nitrogen gas in order to improve the yield after reforming the bitumen or to promote the weighting of the bitumen. Sweeping the gas may be used, and a combination of these may also be used. What is important in the present invention is that the composition of the heavy bituminous part in the obtained thermally modified product is such that the quinoline insoluble content (hereinafter referred to as α component) is 10 to 85% by weight, preferably 20 to 70% by weight. The content of quinoline-soluble and benzene-insoluble components (hereinafter referred to as β component) is adjusted to 5 to 40% by weight, preferably 15 to 30% by weight. α component is 10
If the α component is less than 80% by weight, or if the β component is more than 40% by weight, the molded body will tend to form a foaming state during heat treatment for firing or graphitization.
If the content of the component is less than 5%, sufficient quality cannot be imparted to the final product. The thermally modified product thus obtained is finely pulverized and formed under pressure without adding any additional binder. Various methods can be used for pressure molding, such as uniaxial pressure molding and hydrostatic pressure molding. Next, the calcination, graphitization, or calcination step is omitted and the formed product is directly heat-treated in a graphitization furnace to obtain a high-strength carbonaceous compact. The carbonaceous molded article according to the present invention has the following advantages in terms of quality compared to conventional methods. (1) Dense and strong products can be easily obtained. For example, if finely powdered carbonaceous aggregate is blended, a product with greater strength can be obtained, but with conventional methods, it is difficult to sufficiently spread the binder pitch over the surface of the finely divided carbonaceous aggregate, resulting in a homogeneous product. It was difficult to obtain materials. However, according to the present invention, a large amount of bituminous material is blended into the aggregate and dispersed in the liquid during mixing heat treatment, so that effective viscous components are uniformly dispersed in the aggregate during thermal modification. In addition, since caking occurs mainly on the surface of the aggregate, the amount and quality of carbon produced from the caking material are good, improving strength and other properties. . (2) Products with less variation in quality can be obtained. According to the present invention, since the effective viscous component is uniformly dispersed in the aggregate, expansion and contraction during heat treatments such as calcination and graphitization are performed in a well-balanced manner, resulting in more uniform quality than with conventional methods. The product is easily obtained. (3) Furthermore, according to the present invention, in addition to being dense and having high strength, isotropic products can be easily obtained. The hydrostatic pressure method is generally widely used as a forming method for producing isotropic carbonaceous compacts, which have been in increasing demand in recent years in the fields of carbonaceous materials for nuclear reactors and other structural materials under high temperatures. However, according to the present invention, if conditions are appropriately selected, an isotropic carbonaceous molded body can be easily obtained by ordinary uniaxial pressure molding. The present invention also has the following advantages in terms of manufacturing process. (1) The process can be shortened. According to the conventional method, the process is shortened by performing the binder manufacturing process and the mixing process at the same time, and the firing speed can be increased.
The process that took ~6 months was completed by the method of the present invention.
The process can be shortened to 1 to 2 months. As a result, great effects such as increased flexibility in production planning and faster quality information feedback can be expected. (2) Cost can be reduced. According to the method of the present invention, there is a significant cost reduction due to the simplification of the process and the reduction in crack defects. Furthermore, in order to obtain a normal isotropic carbonaceous molded body, the hydrostatic pressure method is used as a molding method, but in order to obtain a large product using this method, a fairly large-scale equipment is required, and there are limitations to the equipment. The production capacity is inevitably inferior due to the complexity of operations. However, according to the present invention, an isotropic carbonaceous molded body can be easily obtained by ordinary uniaxial pressure molding as described above, and the economic effect is great. The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples unless the gist of the invention is exceeded. Regarding the analysis of solvent-insoluble components in this application, JIS
- The method prescribed in K2425 was followed, but benzene was used instead of toluene as the solvent for the toluene-insoluble component to obtain the benzene-insoluble component. In addition, all evaluations of the carbonaceous molded bodies obtained in the following Examples and Comparative Examples were performed as follows. (Sampling) The obtained carbonaceous molded body was cut in half in the thickness direction, and one side was cut in the A direction (perpendicular to the pressing direction during molding), and the other side was cut in the B direction (perpendicular to the pressing direction during molding). Three test pieces each measuring 8 x 8 x 35 (m/m) were cut out in the parallel direction) to serve as specimens.
Note that unless otherwise specified, values in the A direction are used as representative values. (Measurement method) Measured according to JIS-R7202, and the average value of three chist pieces is shown. Bulk specific gravity: Calculated by dimension and weight method Bending strength: Measured under constant strain using a Tensilon equipped with a 500 kg load cell with a distance between fulcrums of 32 m/m. Electrical specific resistance: Measured by the voltage drop method described in JIS-R7202. Moreover, when simply written as % in the description of Examples, it indicates weight %. Example 1 3240 g of raw pitch coke (volatile content 6.1%) with an average particle size of 6 μm was used as the carbonaceous aggregate, and tar-based soft pitch coke (α component ≒ 0%, β component ≒ 7) was used as the bituminous material.
%) was placed in a 10 autoclave, mixed under nitrogen flow, heated and stirred at 42°C for 10 hours, and thermally modified. The component composition of the heavier bitumen part in the obtained thermally modified product was 20% α component and 28% β component. When the thermally modified product was then treated in air at 200°C for 1 hour, the α and β components were 49% and 22%, respectively. The obtained molded powder was heated at room temperature with a pressure of 1000 kg/cm ²
A molded product of 150 x 220 x 65 m/m was obtained by normal uniaxial pressure molding. This is achieved at a heating rate of 5℃/hr.
Firing was performed at 800°C, and then graphitization was performed by heating to 2800°C for 40 hours to obtain a carbonaceous molded body.
The bulk height of the carbonaceous molded body obtained in this way is 1.85
(g/cm ³ ), its properties were isotropic as shown in Table 1, and it was of high quality.

[Table] Example 2 As carbonaceous aggregates, 350 g of raw pitch coke (volatile content 6.5%) with an average particle size of 22 μm and 700 g of tar-based soft pitch coke (α component ≒ 0%, β component ≒ 7%) were used as carbonaceous aggregates.
420 in the same way as in Example 1 for the stainless steel pot.
Thermal modification was carried out at ℃ for 10 hours. The composition of the heavy bitumen part in the obtained thermally modified material is such that the α component is
55%, and the β component was 17%. Next, the molded powder obtained from this thermally modified product is subjected to normal uniaxial pressure molding at room temperature and a pressure of 1000 kg/cm ² to reduce the diameter.
A molded product with a length of 60 m/m and a thickness of 45 m/m was obtained. This was fired at a maximum temperature of 800°C at a temperature increase rate of 5°C/hr, and then heated to 3000°C for 40 hours to graphitize and obtain a carbonaceous molded body. The bulkiness of the carbonaceous molded body thus obtained was 1.66 (g/cm ³ ), and its properties were isotropic as shown in Table 2.

[Table] Example 3 400 g of raw pitch coke (volatile content 6.5%) with an average particle size of 22μ as the carbonaceous aggregate, and tar-based soft pitch coke (α component ≒ 3.0%, β component ≒ 6.0) as the bituminous material.
%) was placed in one stainless steel pot and thermally modified at 400°C for 10 hours in the same manner as in Example 1. The component composition of the heavier bitumen part in the obtained thermally modified product was 22.3% α component and 25.0% β component. Next, when the thermally modified product was treated in air at 200°C for 1 hour, the α and β components were 37% and 27%, respectively. The obtained molded powder was heated at room temperature with a pressure of 1000 kg/cm ²
Normal uniaxial pressure molding, diameter 60m/m, thickness 45
A molded article of m/m was obtained. This was heated to 3000°C for 40 hours without firing to graphitize it to obtain a carbonaceous compact. The bulkiness of the carbonaceous molded body thus obtained was 1.82 (g/cm ³ ), and its properties were isotropic as shown in Table 3, and it was of high quality.

[Table] Example 4 350 g of raw pitch coke (volatile content 6.5%) with an average particle size of 22μ as the carbonaceous aggregate, and tar-based soft pitch coke (α component ≒ 3.0%, β component ≒ 6.0) as the bituminous material.
%) was placed in one stainless steel pot and thermally modified at 450°C for 4 hours in the same manner as in Example 1. The component composition of the heavier bitumen part in the obtained thermally modified product was 30.7% α component and 25.1% β component. Next, when the thermally modified product was treated in air at 200°C for 1 hour, the α and β components were 68% and 15%, respectively. The obtained molded powder was uniaxially pressed at room temperature and a pressure of 1000 kg/cm ² to obtain a molded product with a diameter of 60 m/m and a thickness of 45 m/m. This can be done in 40 hours without baking.
Graphitization was performed by heating to 3000°C to obtain a carbonaceous molded body. The bulkiness of the carbonaceous molded body thus obtained was 1.66 (g/cm ³ ), its properties were isotropic as shown in Table 4, and it was of high quality.

[Table] Example 5 350 g of calcined pitch coke with an average particle size of 5 μm was used as the carbonaceous aggregate, and 700 g of tar-based soft pitch coke (α component ≒ 0%, β component ≒ 7%) was used as the bituminous material.
Thermal modification was carried out in a stainless steel pot. The component composition of the heavier bitumen part in the obtained thermally modified product was 78% α component and 8% β component. The obtained molded powder was molded at room temperature with a pressure of 1000 kg/cm ² to obtain a molded product with a diameter of 60 m/m and a thickness of 40 m/m. This was heated to a maximum temperature of 800°C at a heating rate of 5°C/hr.
The carbonaceous compact was then fired at 3000° C. for 40 hours to graphitize it. As shown in Table 5, the properties of the carbonaceous molded product obtained in this way showed a strength higher than that of conventional products.

[Table] Example 6 230 g of calcined pitch coke with an average particle size of 3 μm was used as the carbonaceous aggregate, and 805 g of tar-based soft pitch coke (α component ≒ 3%, β component ≒ 6%) was used as the bituminous material.
400 in the same way as in Example 1 for the stainless steel pot.
Thermal modification was carried out at ℃ for 8 hours. The composition of the heavy bituminous material in the obtained thermally modified material is such that the α component is
80%, and the β component was 8%. The obtained molded powder was molded at room temperature with a pressure of 1000 kg/cm ² to a diameter of 60 m/m.
A molded product with a thickness of 40 m/m was obtained. 5℃/hr
Firing was carried out at a maximum temperature of 800°C at a heating rate of , and then graphitized by heating to 3000°C for 40 hours to obtain a carbonaceous molded body. As shown in Table 6, the carbonaceous molded product obtained in this way had considerably higher strength and density than conventional products.

[Table] Example 7 Carbon black (SRF Asahi Carbon Co., Ltd., Asahi #35, average particle size 100 mμ) was used as a carbonaceous aggregate.
805 g of tar-based soft pitch (alpha component ≒ 3%, β component ≒ 6%) as a bituminous material was placed in one stainless steel pot and thermally modified at 400°C for 5 hours in the same manner as in Example 1. The component composition of the heavier bitumen part in the obtained thermally modified product was 78% α component and 12% β component. The obtained molded powder is heated at room temperature and under pressure.
It was molded at 1000 kg/cm ² to obtain a molded product with a diameter of 60 m/m and a thickness of 40 m/m. This was fired at a maximum temperature of 800°C at a temperature increase rate of 5°C/hr, and then heated to 3000°C for 40 hours to graphitize and obtain a carbonaceous molded body.
The properties of the carbonaceous molded body thus obtained were as shown in Table 3.

[Table] Example 8 350 g of raw pitch coke with an average particle size of 22μ as carbonaceous aggregate, tar-based soft pitch (α component ≒
0%, β component≈7%) was placed in one stainless steel pot, and thermally modified at 410°C for 10 hours in the same manner as in Example 1. The component composition of the heavier bitumen part in the obtained thermally modified product was 22.2% α component and 29.4% β component. The thermal reformate is then heated in air.
When treated at 200°C for 1 hour, the α and β components were 39.2% and 29.2%, respectively. The obtained molded powder was uniaxially pressed at room temperature and a pressure of 1000 kg/cm ² to obtain a molded product with a diameter of 60 m/m and a thickness of 45 m/m. This was fired at a maximum temperature of 800°C at a heating rate of 5°C/hr, and then heated again to 3000°C for 40 hours to graphitize and obtain a carbonaceous molded body. The bulkiness of the carbonaceous molded product thus obtained was 1.87 (g/cm ³ ), its properties were isotropic as shown in Table 8, and it was of high quality.

[Table] Comparative example: 400 g of calcined pitch coke with an average particle size of 15μ as carbonaceous aggregate, and 13% α component and β component as bituminous material.
200g of coal tar pitch with 20% ingredients at 180℃
Then, it was kneaded for 1 hour. After pulverizing this compound, it was molded at room temperature with a pressure of 1000 kg/cm ² to a diameter of 60 m/m.
A molded product with a thickness of 45 m/m was obtained. 5℃/hr
Calcination is carried out at a maximum temperature of 800℃ at a heating rate of
Graphitization was performed by heating to 3000°C for 40 hours to obtain a carbonaceous molded body. The bulkiness of the carbonaceous molded body thus obtained was 1.63 (g/cm ³ ), and its properties were as shown in Table 9.

[Table] In addition, the above molded body can be heated in 40 hours without firing.
When graphitized by heating to 3000°C, many cracks occurred and a satisfactory molded product could not be obtained.

Claims (1)

[Claims] 1. Carbonaceous aggregate with bituminous material having a quinoline insoluble content of 5% or less and a benzene insoluble content of 15% or less in a weight ratio of 0.5 to 5.0.
The bituminous material is polycondensed while heating and stirring the obtained mixture, and the composition of the heavy bituminous material in the obtained thermally modified product is 10 to 85% by weight of quinoline insoluble matter and quinoline soluble. A method for producing a high-quality carbonaceous molded article, which comprises molding a thermally modified material in which the benzene-insoluble content is 5 to 40% by weight, and then heat-treating it. 2. The method according to claim 1, which comprises using raw coke as the carbonaceous aggregate and performing the molding by uniaxial pressure molding. 3 Use raw coke as carbonaceous aggregate with an average particle size of 30
The method according to claim 2, which uses a product that has been pulverized to a particle size of less than μ. 4. The method according to any one of claims 1 to 3, which comprises heating the mixture at 350 to 500°C. 5 Heat the thermally modified material at 150-300℃ prior to molding.
5. A method according to any one of claims 1 to 4, comprising heat treatment in air for 10 hours.