JPS63159211A - Carbonaceous powder for hard carbon material and production thereof - Google Patents

Abstract

PURPOSE:To provide carbonaceous powder for the production of hard carbon material having dense texture, high strength and electrical specific resistance, containing a specific amount of a quinoline-soluble component dispersed on the surface of free carbon and containing a specific amount of a benzene-soluble component in said quinoline-soluble component. CONSTITUTION:The objective carbonaceous powder contains a quinoline-soluble component existing at the circumference of free carbon such as coal tar or coal tar pitch and has the following composition. The amount of the quinoline- soluble component is 5-30pts.wt. per 100pts.wt. of the free carbon and the amount of benzene-soluble component in the quinoline-soluble component is 5-50pts.wt. per 100pts.wt. of benzene-insoluble component in the quinoline- soluble component. The carbonaceous powder having the above composition can be produced by repeating extraction and filtration of free carbon-containing coal tar or tar pitch 1-3 times with 200-1,000pts.wt. (based on 100pts.wt. of the raw tar or pitch) of benzene, tar middle oil, etc., having low solubility of pitch compared with quinoline.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention can easily produce hard carbon materials that are widely used in the fields of mechanical carbon such as mechanical seals and bearings, structural materials for the chemical industry, and carbon brush materials. The present invention relates to the composition of carbonaceous powder that can be manufactured, and particularly to improved technology and new products that are characterized by having a composition that can be manufactured without using a binder.

(Prior Art) Carbon materials are usually produced by adding a binder such as coal tar pitch to aggregate coke, kneading the mixture, and subjecting it to the complicated steps of pulverization, molding, calcination, and graphitization. However, according to this method, the process of adding a binder such as coal tar pitch to aggregate coke, mixing and crushing is complicated, which increases production costs, and the aggregate coke generated in this mixing process is complicated. Also, gas and dust from the binder pitch created a poor working environment and caused sanitary problems. In addition, carbon materials produced by the method have a large number of pores due to the volatile matter generated during the calcination process due to the porosity of the aggregate coke and the presence of binder pitch, and the resulting carbon The material also has the disadvantage of being porous, dense, and difficult to achieve high strength.

Due to the above-mentioned drawbacks, when used as a sealing material for machinery, for example, impregnation treatment with resin or the like is performed to fill the pores and prevent gas or liquid leaks. Measures are taken to prevent this, but in such cases, the high temperature stability, which is an original characteristic of carbon materials, is lost, which poses a problem.

On the other hand, various measures have been taken to improve this porosity from the perspective of producing carbon materials. For example, if the raw material, aggregate coke, is ultra-finely pulverized to several micrometers or less,
Improving the kneading method to reduce the amount of binder pitch added as much as possible, or impregnating with pitch and then firing again to fill the pores created during the firing process. repeated. However, ultra-fine pulverization and pitch impregnation treatment of aggregate coke are difficult processes, which significantly increase manufacturing costs. had some difficult aspects.

In contrast to these conventional manufacturing methods, research has been actively conducted in recent years to solve the drawbacks of conventional carbon materials such as porosity and low strength by manufacturing carbon materials without using binder pitches. It is.

For example, Tokukai Showa 4! Publication J-23791 and Japanese Unexamined Patent Publication No. 1983
-157791 proposes a method that uses pitch as a raw material, heat-treats it at a high temperature of 400 to 500°C, and utilizes mesophase spherules with a size of several microns to several tens of microns produced at this stage. .

Furthermore, Japanese Patent Application Laid-Open No. 54-64096 proposes a method of utilizing carbonaceous powder obtained by grinding or pulverizing raw coke heat-treated at about 600° C. or lower.

(Problems to be Solved by the Invention) The above-mentioned prior art discloses a method for producing a high-density and high-strength carbon material without using binder pitches. However, for example, the method using mesophase spherules involves a difficult process of heat-treating pitch at a high temperature of 400 to 500°C to generate mesophase spherules, and the particle size of mesophase spherules is usually several microns to several microspheres. Although it is a sphere with a size of 10μ and provides a carbon material with a finer and denser structure than the conventional method using aggregate coke, it completely prevents gas leaks or liquid leaks, for example. However, in fields such as mechanical carbon, where this is required, there are still some aspects that are insufficient. Furthermore, since the mesophase spherule itself is a crystalline graphite precursor with a hexagonal network structure, it exhibits relatively high electrical conductivity and is suitable for fields that require high electrical resistivity, such as rectifying brush materials. It was inappropriate.

On the other hand, according to the method of grinding raw coke heat-treated at 600°C or less, the raw coke changes to amorphous state due to the grinding process, so the carbon material is harder than that of the mesophase spherules described above. However, the drawback is that the grinding process takes an extremely long time and is inefficient.

In view of these drawbacks, the object of the present invention is to economically produce a hard carbon material having constituent particles of 1 μm or less, a very dense structure, and a high electrical resistivity without using a binder. An object of the present invention is to provide a carbonaceous powder capable of producing carbonaceous powder and a method for producing the same.

(Means for Solving the Problems) The present invention has been made by focusing on the problems of the prior art described above, and includes a quinoline-soluble component (hereinafter referred to as a QS component) surrounding the free carbon of coal tar or coal tar pitch. A carbonaceous powder having a composition ratio of 5 to 30 parts by weight of a quinoline-soluble component to 100 parts by weight of free carbon, and a benzene-soluble component (hereinafter referred to as B) in the quinoline-soluble component.
A carbon material for hard carbon materials, characterized in that the ratio of benzene-insoluble component (hereinafter referred to as S component) to benzene-insoluble component (hereinafter referred to as BI acid component) is 5 to 50 parts by weight per 100 parts by weight of benzene-soluble component. The present invention was achieved by developing a powder.

The above-mentioned adjusted carbonaceous powder is molded, fired, and graphitized according to a conventional method without using a binder pitch, so that it has a bulk density of 1.5 to 1.88 g/cm.
', bending strength 700-1,000 kg/cm'', Shore hardness 85-120, electrical resistivity 3.000-5.0
00 μΩ-cm and an average pore radius of 0.1 μm or less can be produced.

Coal tar and the cool pitch obtained by distilling it originally contain fine carbon particles (61 μm) called free carbon. Free carbon is amorphous carbon that is thought to be produced by a gas phase pyrolysis reaction of coke oven gas that is rapidly heated to a high temperature in a coke oven. component). On the other hand, coal cour and coal tar pitch are 400 to 50
The mesophase spherules that are generated in the pitch matrix during heat treatment at a temperature of 0°C are also substantially considered as QI components, but mesophase spherules are usually generated when pitches undergo a liquid phase carbonization reaction. Basically, it has a crystalline hexagonal network graphite-like structure, which is fundamentally different from amorphous free carbon.

The present inventors have focused on free carbon, which is amorphous fine particles of 1 μm or less, and have conducted extensive research into producing a hard carbon material using this as a raw material. As a result, free carbon itself has no self-sintering properties, unlike mesophase spherules. However, when separating free carbon from coal cool and coal tar pitch, it is possible to leave the β component (BI acid component in the QS component) to produce a carbon material without using binder pitch during molding. Since free carbon is amorphous carbon particles with a particle size of 1μ or less, we have discovered that it can be a carbon material with a dense structure, high electrical resistivity, and high strength.Moreover, we are continuing to conduct further research. However, in order to obtain industrially stable and dense hard carbon materials, it is necessary to add Q to 100 parts by weight of free carbon.
S component is 5 parts by weight (preferably 10 parts by weight) or more, 30 parts by weight
In addition, the BS component in the QS component should be at least 5 parts by weight (preferably 10 parts by weight) and 1 part by weight (preferably 30 parts by weight) per 100 parts by weight of the BT component (i.e., β component). It has been found that it is necessary for the weight to be less than 1 part). In other words, the β component has a strong cohesive force 1 and achieves strong adhesion between free carbon particles during the firing process of the compact, but the presence of a small amount of the BS component is necessary for the development of this strong adhesion. I confirmed that it is. The abundance ratio of the BS component is from 5 parts by weight (preferably 10 parts by weight) to 50 parts by weight (preferably 30 parts by weight) based on 100 parts by weight of the β component, and if the BS component is less than 5 parts by weight, Strong adhesion between free carbon particles is not developed, resulting in a carbon material with extremely low strength. On the other hand, the BS component is 5
If it exceeds 0 parts by weight, the fired product will contain 111if! This phenomenon occurs and carbon materials cannot be obtained. Furthermore, this β component and B
If the sum of the S components, that is, the QS component, is not more than 5 parts by weight (preferably 10 parts by weight) per 100 parts by weight of free carbon, the overall binder force will be insufficient, a strong fired body will not be obtained, and the QS component If it exceeds 30 parts by weight, a large amount of volatile matter is generated during firing, which not only tends to cause phenomena such as swelling and cracking in the fired product, but even if the fired product is obtained, it becomes porous and contains a dense carbon material. It becomes difficult to obtain.

The above causes are assumed to be as follows.

In order for the β component to exert a strong cohesive force and to firmly adhere the free carbon particles, it is necessary for the carbonization reaction to proceed while the molded body undergoes a slight softening state during the firing process. However, B.S.
In a system in which the component is not present at all, the β component does not soften at all and the carbonization reaction proceeds in a solid state, resulting in no strong adhesion between the free carbon particles. However, in a system where several percent of the BS component is present, the β component easily shows a softened state during the firing process. Moreover, B.S.
It is observed that the viscosity tends to decrease as the amount of the component increases. As a result, strong adhesion between free carbon particles was developed in the system of β component and BS component, and B
If the amount of the S component increases too much relative to the β component, the fluidity of the QS component will increase, eventually causing swelling in the fired product. Further, the amount of QS component relative to the amount of free carbon is determined by the amount necessary for uniformly dispersing the QS component on the free carbon surface. That is, when the QS component is uniformly dispersed on the free carbon surface, sufficiently strong adhesion can be achieved if the QS component is 5 parts by weight (preferably 10 parts by weight) or more per 100 parts by weight of free carbon. If the amount exceeds 30 parts by weight, as mentioned above, volatile matter from the QS component during firing will increase, causing swelling and cracking of the fired product, or conversely, it will become a porous carbon material.

It is important that the free carbon and QS components of the carbonaceous powder of the present invention are uniformly dispersed.

Next, a method for manufacturing the carbonaceous powder for hard carbon materials of the present invention will be specifically explained. In the first production method, coal tar containing free carbon or heat treatment (
This is usually achieved under conditions of 380°C or lower. This can be achieved by using coal tar pitch subjected to the above process as a raw material and separating free carbon and β components from the pitch matrix by solvent extraction. Solvents to be used include benzene, toluene, pyridine, cool medium oil, tar light oil, which has a weaker pitch dissolving power than quinoline.
Furthermore, a mixture of these solvents can be used, and the extraction operation uses 200 parts by weight of raw material tar or pitch.
Repeat 1 to 3 times using ~i, ooo parts by weight of solvent. In this case, exhaustive extraction operations using too much solvent should be avoided. This is because by performing a thorough extraction operation, the amount of BS components remaining in the product (filter cake) is extremely reduced, making it impossible to obtain the desired carbonaceous powder. The desired carbonaceous powder can be obtained by performing extraction and filtration operations 1 to 3 times using 1 to 1.000 parts by weight of a solvent.

The second production method involves dividing the raw material coal tar or coal tar pitch into a Ql component and a QS component in advance, and if necessary, further dividing the O8 component into an 81 component and a BS component using a solvent.
This is a method of recombining this at a predetermined ratio. This method has the advantage of being able to adjust each component in any proportion;
There is a problem in that it is difficult to uniformly disperse the O3 component around the free carbon, which is an important point of the present invention.

As a means to overcome this, the desired carbonaceous powder can be obtained by dispersing free carbon in a solvent in which the QS component is dissolved, such as quinoline or cool heavy oil, and then removing the solvent by vacuum distillation.

A hard carbon material can be obtained from the carbonaceous powder prepared by the above-described method by directly molding, firing, and graphitizing the powder without using a binder pitch or the like. The main physical properties of the obtained hard carbon material are a bulk density of 1.5 to 1.8 g/cm3, a bending strength of 700 to 1.000 kg/cm3, and a Shore hardness of 85.
~120, electrical specific resistance 3.000~5.000 μΩ-c
m, and the average pore radius is 0.1μ or less.

These physical property values vary depending on the composition of the carbonaceous powder, and generally, as the amount of QS component relative to QI component in the composition increases, bulk density, bending strength, and Shore hardness tend to increase, and electrical resistivity tends to decrease. becomes. Furthermore, the average pore radius is not affected much by the composition of the carbonaceous powder.

(Effects of the Invention) As explained above, according to the present invention, a dense structure with a particle size of 1μ or less and an average pore radius of 0.1μ or less, high strength,
A hard carbon material with electrical resistivity can be stably produced without using a binder.

(Example 1) Coal tar containing 10% free carbon was extracted and filtered using oil in tar. The amount of oil in tar used was 600 parts by weight per 100 parts by weight of coal tar, the extraction temperature was 100° C., and the extraction time was 30 minutes. After washing this extraction residue with tar light oil, under vacuum (10 mmAg)
The target carbonaceous powder was obtained by drying at 150° C. for 2 hours. The industrial analysis values of this powder are B1: 95.5% by weight and Q
I: 82.0% by weight.

That is, BS: 4.5% by weight, β: 13.5% by weight and Q
S: 18.0% by weight, the amount of QS component relative to 100 parts by weight of Ql component was 22% by weight, and the amount of BS component in the QS component was 33.3% by weight relative to 100 parts by weight of β component.

Using a rubber press, the above raw materials are 80φ×30Hm/
It was molded into a molded body of m size. Molding pressure is 600kg/
cm2. The molded body is heated to 1,000 ml in coke pleat.
It was fired at 0°C, and then further graphitized at 2,500°C. The physical properties of the obtained carbon material were investigated and the values are shown in Table 1. Further, FIG. 1 shows the pore distribution (measured by a mercury borosimeter) of the manufactured carbon material.

Table 1 Physical property values of graphite material according to Example 1 Class 1.65
115 3750 830 (Example 2) Coal tar containing 7% free carbon was extracted and filtered using oil in tar. The amount of oil in tar used was 500 parts by weight per 100 parts by weight of coal tar, the extraction temperature was 120°C, and the extraction time was 60 minutes. This extraction residue was washed with tar light oil and then under vacuum (10 m
mAg) was dried at 150° C. for 2 hours to obtain a raw material for producing a carbon material. The industrial analysis values of this raw material were BI: 96.3% by weight and QI: 80.3% by weight. That is, BS:3
．． 7% by weight, β: 16.0% by weight, and QS: 19.7% by weight, the amount of QS component is 24.5 parts by weight per 100 parts by weight of Ql component, and the amount of QS component is per 100 parts by weight of β component. The total amount was 23.1 parts by weight.

Using a rubber press, the above raw materials are 80φX30Hm/
It was molded into a molded body of m size. Molding pressure is 600kg/
cm'. The physical properties of the carbon material obtained in the same manner as in Example 1 were examined below, and the values are shown in Table 2. Furthermore, FIG. 2 shows the pore distribution of the produced carbon material (measured using a mercury borosimeter).

Table 2 Physical property values of graphite material according to Example 2
．． 75 110 3300 920
(Example 3) Coal tar containing 10 parts by weight of free carbon was
Coal tar pitch was distilled at 70°C to obtain f4.

When this coal tar pitch was observed under a polarizing microscope, it was confirmed that no mesophase spherules were formed. ? The tampered coal tar pitch was solvent fractionated into a Ql component, a β component, and a BS component using phosphorus and benzene, and then recombined in the proportions shown in Table 3 to obtain the desired carbonaceous powder.

The recombining method is to convert the β component and BS component into β component BS component (
That is, 100 parts by weight of the QS component is dissolved in 1.000 parts by weight of quinoline, and then a predetermined amount of the QI component is mixed and stirred under vacuum (3 mmHg) at a temperature of 120
Quinoline was removed by distillation under reduced pressure at ℃.

In this way, QS is applied to the surface of the QI component (free carbon).
The components were uniformly adhered, and then the obtained carbonaceous powder was molded at a compacting pressure of 800 kg/cm2 to 50φ×20) (m/
A molded body having a size of m was molded, followed by firing at 1.000°C and graphitization treatment at 2.500°C, and various physical properties were investigated. The results are shown in Table 3.

The average pore radius of the graphite materials with Nα1 and 2.4 in Table 3 was 0.070, 0.068, and 0.069μ, respectively.

[Brief explanation of the drawing]

Figure 1 is a curve diagram plotting the average pore radius of the graphite material produced according to Example 1, and Figure 2 is a curve diagram plotting the average pore radius of the graphite material produced according to Example 2. It is.

Claims (1)

[Claims] 1. A carbonaceous powder having a quinoline-soluble component surrounding free carbon of coal tar or coal tar pitch, the composition ratio of which is 5 to 5 parts by weight of the quinoline-soluble component per 100 parts by weight of free carbon. 30 parts by weight, and the ratio of benzene-soluble components to benzene-insoluble components in the quinoline-soluble components is 5 parts by weight to 100 parts by weight of benzene-insoluble components.
50 parts by weight of carbonaceous powder for hard carbon materials. 2. A carbonaceous powder having a quinoline-soluble component around the free carbon of coal tar or coal tar pitch, the composition ratio of which is 5 to 30 parts by weight of the quinoline-soluble component to 100 parts by weight of free carbon, and The ratio of the benzene soluble component to the benzene insoluble component in the quinoline soluble component is 5 parts by weight per 100 parts by weight of the benzene insoluble component.
~50 parts by weight of carbonaceous powder for hard carbon materials, coal tar or tar pitch containing free carbon, benzene, which has a weaker dissolving power for pitch than quinoline,
It is characterized by performing extraction and filtration operations 1 to 3 times using toluene, pyridine, oil in tar, via tar, or a mixed solvent thereof in an amount of 200 to 1000 parts by weight per 100 parts by weight of raw material tar or pitch. A method for producing carbonaceous powder for hard carbon materials. 3. A carbonaceous powder having a quinoline-soluble component around the free carbon of coal tar or coal tar pitch, the composition ratio of which is 5 to 30 parts by weight of the quinoline-soluble component to 100 parts by weight of free carbon, and The ratio of the benzene soluble component to the benzene insoluble component in the quinoline soluble component is 5 parts by weight per 100 parts by weight of the benzene insoluble component.
A hard carbon material characterized in that ~50 parts by weight of carbonaceous powder for hard carbon materials is obtained by dispersing free carbon in a solvent in which a quinoline soluble component is dissolved, and then removing the solvent by vacuum distillation. Method for producing carbonaceous powder for use.