JPH06145669A - Self-fusible carbonaceous powder and high-density carbon material - Google Patents

Abstract

PURPOSE:To obtain the subject powder, having specific atomic ratios of hydrogen and oxygen to carbon and suitable as a raw material, etc., for high-density carbon materials by heat-treating mesophase pitch having a specific carbonization yield, a specified softening point and a specific optically anisotropic phase. CONSTITUTION:Mesophase pitch, obtained by polymerizing naphthalene in the presence of a superstrong acid HO-BF3 and having >=70wt.% carbonization yield, >=170 deg.C softening point and >=70vol.% optically anisotropic phase is heated to 480 deg.C at 300 deg.C/hr rate in a nitrogen atmosphere and then heat-treated for 30min. Thereby, since the burning is achieved in a short time to provide a sufficiently high-density and high-strength carbon material simply by the burning at a time and excellent tackiness is imparted by moderate heat treatment, the objective self-fusible carbonaceous powder, having the atomic ratio of hydrogen to carbon within the range of 0.35-0.48 and <0.01 atomic ratio of oxygen to carbon and suitable as a binder for carbon composite materials, etc., is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-fusing carbonaceous powder suitable as a raw material for high-density carbon materials and a binder for carbon composite materials, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, many manufacturing methods for high-density carbon materials are known, but they are roughly divided into the following two methods from the viewpoint of starting materials. One method is a method in which an aggregate such as coke powder, natural graphite, or carbon black and a binder such as coal tar pitch are kneaded, and then molded and fired. In this method, since the residual carbon content of the binder is very low, the density of the molded body is very small in one carbonization, and in order to increase the density, the impregnation / carbonization process must be repeated many times to densify. In addition, in the carbonization process, volatile components in the binder are degassed, and sudden escape of gas not only leaves heterogeneous pores inside the molded body, but also causes expansion of the molded body and causes tissue destruction. Therefore, in order to prevent such an adverse effect, a very slow temperature rise of 2 to 10 ° C / hr is carried out in the carbonization step, and a production period of 3 to 4 weeks is required. The molded body that has undergone this carbonization step is fired at 2500 to 3000 ° C. to produce a graphitic carbon material depending on the application, but this graphitization step generally requires 2 to 3 weeks. As described above, it takes a long time of 2-3 months to manufacture a graphitic carbon material from an aggregate such as coke and a binder such as coal tar pitch through a complicated process.

Another method uses no binder,
This is a method of using optically anisotropic small spheres as a raw material for a high-density carbon material. That is, the optically anisotropic small spheres (mesophase spherulites) produced during the heat treatment of coal tar pitch or heavy petroleum oil at 350 to 500 ° C were separated and dried from the pitch matrix by solvent fractionation. This is a method in which mesophase spherulites are used as a raw material, and this is pressure-molded and then fired, and a high-density and isotropic carbon material can be manufactured. However, in this method, a large amount of extraction solvent is required in the spherulite / separation step, and solvent separation must be repeated many times, and it is difficult to completely remove the residual solvent from the obtained spherulite. Therefore, it tends to cause cracking and expansion of the molded body in the subsequent carbonization step. Moreover, in such a spherulite solvent extraction method, in addition to the low separation yield, it is not easy to control the properties of the formed spherulites, and there are many industrial problems in stably producing a constant quality raw material.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Since the process for producing a high-density carbon material is extremely complicated and requires a very long production period as described above, a high-density carbon material produced by a conventional method is It is expensive, and as a result, it is currently severely restricted in its field of use. Therefore, it is one of the major problems in the carbon industry to greatly simplify the manufacturing process of the high-density carbon material and shorten the manufacturing period. An object of the present invention is to provide a self-fusing carbonaceous powder that can produce a high-density and high-strength carbon material in a short time and at low cost, and a method for producing the same.

[0005]

[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the inventors have found that by heat-treating a specific mesophase, the atomic ratio (H / C) of hydrogen to carbon within a certain range and the ratio of hydrogen to carbon Add a binder by preparing a heat-treated pitch with an atomic ratio of oxygen (O / C) and using this heat-treated powder with enhanced carbonization yield and excellent self-fusion properties as a raw material. The inventors have found that a high-density carbon material can be obtained in a short time and at low cost without causing the present invention.

That is, according to the present invention, the carbonization yield is 70% by weight or more, the softening point is 170 ° C. or more, and the optically anisotropic phase is 70 vol%.
Obtained by heat treatment of the above mesophase pitch, the atomic ratio of hydrogen to carbon is in the range of 0.35 to 0.48, and the atomic ratio of oxygen to carbon is less than 0.01 self-fusing carbonaceous powder, and That is the manufacturing method.

The carbon, hydrogen and oxygen contents of the self-fusing carbonaceous powder of the present invention are analyzed by using an automatic analyzer which applies a technique such as detection by the thermal conductivity of combustion gas. The raw material pitch for producing the self-bonding carbonaceous powder of the present invention has a carbonization yield of 70% by weight or more, preferably
A mesophase pitch of 80 wt% or more is used. This carbonization yield is obtained by gradually raising the pitch in an inert atmosphere to 600
It is a value when the temperature is maintained for 2 hours after reaching ℃. When pitch with a low carbonization yield is used as a raw material, voids are easily generated by volatile gas in the carbonized molded product, which leads to a decrease in the density of the resulting carbon material, its mechanical strength, electrical conductivity, and thermal conductivity. Since it has a bad influence on corrosion resistance and the like, it is important to use a raw material pitch having a high carbonization yield.

This raw material pitch has a softening point of 170 ° C. or higher by a flow tester and an optically anisotropic phase observed by a polarization microscope of at least 70 vol% or more, preferably 80 vo
A mesophase pitch of 1% or more, more preferably substantially 100 vol% is used. The mesophase pitch satisfying these conditions may be either coal-based or petroleum-based, but especially aromatic carbonization described in JP-A 1-13621, 1-254796 and 2-223391. Hydrogen is a super strong acid H
The mesophase pitch produced by polymerizing with an F-BF ₃ catalyst is preferably used because a high carbonization yield can be obtained.

The self-fusing carbonaceous powder of the present invention is produced by heat-treating the above mesophase pitch. This heat treatment condition is the atomic ratio of hydrogen to carbon (H / C)
Is in the range of 0.35 to 0.48 and the atomic ratio of oxygen to carbon (O / C) is less than 0.01, and heat treatment conditions may be selected so that a self-bonding carbonaceous powder can be obtained, and there is no particular limitation.
Generally, the above mesophase pitch is stirred at 470-
The heat treatment is carried out at a temperature of 550 ° C.

In the present invention, the above mesophase pitch is prepared in such a way that good moldability can be obtained, and a high density can be achieved without inducing cracking or expansion in the subsequent carbonization step. That is, by performing such an appropriate heat treatment, the initial stage of carbonization of the molded body
Good melt fluidity is guaranteed at (400 ~ 600 ℃),
As a raw material for a high-density carbon material, it can be reformed into a powder having a self-bonding property that exhibits excellent performance (Examples 1 and 2).

Excessive heat treatment lowers the fusion property of the mesophase pitch powder, and a carbon material having desired performance cannot be obtained (Comparative Example 1). On the other hand, if the heat treatment is insufficient, the molded body is likely to expand or foam due to the volatile gas in the subsequent carbonization step, and the desired carbon material cannot be obtained (Comparative Example 2). In addition, as the oxygen content of the heat-treated pitch increases, the carbonization yield decreases and the fusion property decreases, which is not preferable (Comparative Example 3).

That is, by appropriately performing the heat treatment of the mesophase pitch so that H / C and O / C satisfy the above range, the carbonization yield is further enhanced, and the carbonization process is performed while maintaining the adhesiveness of the mesophase pitch. Since the gas generated in step 2 can be removed as much as possible, it is possible to manufacture a high-density and high-strength carbon material with only one firing.

In order to obtain a high-density and high-strength carbon material, the mesophase pitch thus heat-treated is first made into powder. The powdering method and the powder shape are not particularly limited. The particle size distribution is also not particularly limited, but a particle size distribution that maximizes the packing density during molding is preferable. Generally, a powder of 200 to 5 μm is used for molding.

Next, the powdered heat-treated pitch is molded. At this time, a binder is not particularly necessary. The shape of the molded body can be freely selected according to the purpose, application and the like. Molding may be carried out at room temperature or in a temperature range in which the heat-treated powder softens or melts, which is determined according to the required shape, performance and cost. The molded body is subsequently fired to produce the desired carbon material. Firing conditions are generally in a non-oxidizing atmosphere and at a temperature rising rate of 1 to 300 ° C / h.

[0015]

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples.

Example 1 Mesophase pitch AR-1 (softening point> 300 ° C., carbonization yield 91 wt%, optical anisotropy content) obtained by polymerizing naphthalene in the presence of superacid H0-BF ₃ (100 vol%) was heated to 480 ° C at 300 ° C / h in a nitrogen atmosphere and heat-treated for 30 minutes. The H / C of this heat treatment pitch was 0.47, and the O / C was 0.006. After grinding the heat treated pitch below 74 .mu.m, the plate-shaped (50 mm × at a molding pressure 1200 kg / cm ² at room temperature
Molded into 50mm x 10mm). Then, the temperature was raised up to 600 ° C at 60 ° C / h under nitrogen flow and kept for 2 hours. The carbonization yield was 97 wt%. Then, by firing for 2 hours at 1300 ° C. under a flow of argon, a carbide of 50 mm × 50 mm × 10 mm was obtained. Further, this carbide was calcined at 1900 ° C for 2 hours. Table 1 shows the physical properties of the obtained carbide (bulk density, compressive strength, bending strength).

Example 2 Mesophase pitch AR-2 (softening point 220 ° C., carbonization yield, obtained by polymerizing naphthalene in the presence of super strong acid HF-BF ₃
83 wt%, optical anisotropic content 100 vol%) under nitrogen atmosphere
The temperature was raised to 505 ° C at 300 ° C / h and heat treatment was performed for 2 hours. The H / C of this heat treatment pitch was 0.44 and the O / C was 0.005.
After crushing this heat-treated pitch to 74 μm or less, at room temperature with a molding pressure of 1200 kg / cm ² in plate form (50 mm × 50 mm × 10 m
m). After that, under nitrogen flow up to 600 ℃ 80 ℃ / h
The temperature was raised by and the temperature was maintained for 2 hours. The carbonization yield was 97 wt%.
Further, this was fired at 1300 ° C. and 1900 ° C., and the physical properties of the obtained carbide are shown in Table 1.

Comparative Example 1 Using the same mesophase pitch AR-2 as in Example 2, this was heated to 510 ° C. at 300 ° C./h for 5 hours in a nitrogen atmosphere. The H / C of this heat treatment pitch was 0.34 and the O / C was 0.005. This heat-treated powder was molded under the same conditions as in Example 2.
It was calcined at 600 ° C, and further calcined at 1300 ° C and 1900 ° C. Table 1 shows the physical properties of the obtained carbide. Since the H / C of this heat-treated powder was lower than the claimed range, the self-bonding property was lost, and a large amount of black carbon powder adhered to the hands.

Comparative Example 2 Mesophase pitch AR-3 (softening point 230 ° C., carbonization yield, obtained by polymerizing naphthalene in the presence of super strong acid HF-BF ₃
85wt%, optically anisotropic content 100vol%) under nitrogen atmosphere
The temperature was raised to 400 ° C at 300 ° C / h and heat treatment was performed for 14 hours. The H / C of this heat treatment pitch was 0.51 and the O / C was 0.005.
This heat-treated powder was tried to be calcined at 600 ° C. under the same conditions as in Example 1, but the H / C was higher than the claimed range, so that the expansion of the molded body occurred and the physical properties of the carbide could not be measured.

Comparative Example 3 Using the same mesophase pitch AR-3 as in Example 1, this was heated to 450 ° C. at 300 ° C./h in a nitrogen atmosphere and heat-treated for 30 minutes. During this heat treatment, some air was blown in temporarily. The H / C of this heat treatment pitch was 0.36 and the O / C was 0.02. Hereinafter, firing was performed in the same procedure as in Example 1. In this comparative example, the O / C of the heat treatment pitch is higher than the claimed range.
As shown in, no high performance carbon material was obtained.

[0021]

[Table 1]

[0022]

The carbonaceous powder of the present invention is a heat-treated mesophase pitch which is easy to carbonize and graphitize as a raw material for high-density carbon materials and has a very high carbonization yield, so that firing can be achieved in a short time. In addition, a carbon material with sufficient high density and high strength can be obtained by firing only once. Further, the structure of the fired body derived from the mesophase pitch exhibits optical anisotropy and is highly dense and highly pure, so that the carbon bond formed is very strong. This carbon bond has a higher degree of graphitization by firing at a high temperature, and further densification due to shrinkage, so that the carbon bond becomes stronger. In addition, since the mesophase pitch used in the present invention is imparted with excellent tackiness by an appropriate heat treatment, a binder is not particularly necessary. Therefore, if the carbonaceous powder of the present invention is used, a high-density and high-strength carbon material can be easily produced in a short time at low cost, and the industrial significance of the present invention is extremely great.

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[Procedure amendment]

[Submission date] May 21, 1993

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[0004]

As described above, the process for producing a high-density carbon material is extremely complicated and requires a very long production period. Therefore, the high-density carbon material produced by the conventional method is expensive. Therefore, at present, the field of use is severely restricted. Therefore, in the case of a high-density carbon material, voids due to volatile gas are easily generated in the carbonized molded body, and it is a major problem in the carbon industry to greatly simplify the manufacturing process of the obtained carbon material and shorten the manufacturing period. one of. An object of the present invention is to provide a self-fusing carbonaceous powder and a high-density carbon material that can produce a high-density and high-strength carbon material in a short time and at low cost.

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[0005]

[Means for Solving the Problems] As a result of intensive studies aimed at achieving the above-mentioned objects, the inventors of the present invention have found that by heat-treating a specific mesophase pitch, the atomic ratio of hydrogen to carbon (H / C) and oxygen in a certain range are increased. Atomic ratio of oxygen to (O /
By preparing a heat-treated pitch with (C) and using this heat-treated powder with enhanced carbonization yield and excellent self-fusion properties as a raw material, it is possible to increase the cost quickly and inexpensively without adding a binder. The inventors have found that a high density carbon material can be obtained, and completed the present invention.

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That is, according to the present invention, the carbonization yield is 70% by weight or more, the softening point is 170 ° C. or more, and the optically anisotropic phase is 70 vol%.
Obtained by heat treatment of the above mesophase pitch, the atomic ratio of hydrogen to carbon is in the range of 0.35 to 0.48, and the atomic ratio of oxygen to carbon is less than 0.01 self-fusing carbonaceous powder, and It is a high-density carbon material obtained by molding this, then heating it to a temperature of 600 to 1600 ° C in a non-oxidizing atmosphere, or graphitizing it at a higher temperature.

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In order to obtain a high-density and high-strength carbon material, the mesophase pitch thus heat-treated is first made into powder. The powdering method and the powder shape are not particularly limited. The particle size distribution is also not particularly limited, but a particle size distribution that maximizes the packing density during molding is preferable. Generally, powder of 200 to 1 μm is used for molding.

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Next, the powdered heat-treated pitch is molded. At this time, a binder is not particularly necessary. The shape of the molded body can be freely selected according to the purpose, application and the like. Molding may be carried out at room temperature or in a temperature range in which the heat-treated powder softens or melts, which is determined according to the required billing, performance and cost. The molded body is subsequently fired to produce the desired carbon material. The firing conditions are generally performed by heating the molded body to a temperature of 600 to 1600 ° C and carbonizing it in a non-oxidizing atmosphere at a heating rate of 1 to 300 ° C / h. If necessary, a step of graphitizing at a higher temperature can be included.

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Comparative Example 1 Using the same mesophase pitch AR-2 as in Example 2, this was heated to 540 ° C. at 300 ° C./h in a nitrogen atmosphere and heat-treated for 5 hours. The H / C of this heat treatment pitch was 0.34 and the O / C was 0.005. This heat-treated powder was molded under the same conditions as in Example 2.
It was calcined at 600 ° C, and further calcined at 1300 ° C and 1900 ° C. Table 1 shows the physical properties of the obtained carbide. Since this heat-treated powder had a low H / C, the self-bonding property was lost, and a large amount of black carbon powder adhered to the hands. ─────────────────────────────────────────────────── ───

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[Submission date] May 26, 1993

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Next, the powdered heat-treated pitch is molded. At this time, a binder is not particularly necessary. The shape of the molded body can be freely selected according to the purpose, application and the like. Molding may be carried out at room temperature or in a temperature range where the heat-treated powder softens or melts, which is determined according to the required shape, performance and cost. The molded body is subsequently fired to produce the desired carbon material. The firing conditions are generally a non-oxidizing atmosphere and a heating rate of 1
It is carried out by heating the molded body to a temperature of 600 to 1600 ° C at ~ 300 ° C / h to carbonize it. If necessary, a step of graphitizing at a higher temperature can be included.

Claims (2)

[Claims] 1. A carbonization yield of 70% by weight or more and a softening point of 170 ° C.
As described above, the optically anisotropic phase is obtained by heat-treating the mesophase pitch having 70 vol% or more, the atomic ratio of hydrogen to carbon is in the range of 0.35 to 0.48, and the atomic ratio of oxygen to carbon is less than 0.01. Is a self-bonding carbonaceous powder. 2. A carbonization yield of 70% by weight or more and a softening point of 170 ° C.
As described above, the optically anisotropic phase is characterized by being prepared by heat-treating the mesophase pitch having 70% or more, the atomic ratio of hydrogen to carbon is in the range of 0.35 to 0.48, and of oxygen to carbon. A method for producing a self-bonding carbonaceous powder having an atomic ratio of less than 0.01.