JPH0543318A - Composition for carbonaceous form - Google Patents

Abstract

PURPOSE:To provide a high-density composition suitable for producing high- density carbonaceous forms of high mechanical strength, e.g. carbonaceous electrodes. CONSTITUTION:The objective composition can be obtained by incorporating (A) a caking agent in (B) raw pitch coke powder 1-250mum in mean particle size containing 5-20wt.% of volatiles, or (C) a mixture of the component B and calcinated coke, artificial graphite and/or carbon black each 10-250mum in mean particle size.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbon material composition for producing a carbon material having a high density and a high strength, for example, a carbon electrode.

[0002]

2. Description of the Related Art Carbon compacts are carbon aggregates (fillers) to which a binder is added, molded and fired. Various compacts such as carbon electrodes, refractories, electric brushes, etc. are manufactured. Has been done. And, conventionally, the aggregate of carbon material (filler)
As artificial graphite, calcined coke and those
Those containing Bonblack have been mainly used. However, artificial graphite and carbon compacts mainly composed of calcined coke have a limited bond between the aggregate and the binder, and cannot provide sufficient strength. There is a drawback that the consumption rate of the carbon electrode used is large.

[0003]

Therefore, the inventor of the present invention
As a result of various studies to improve the above-mentioned drawbacks, it was found that a carbon compact capable of reducing the consumption rate of the carbon electrode is more effective as it is dense and has higher strength, and based on this finding, high density and high strength are obtained. As a result of conducting research and development to obtain a carbon electrode of carbon dioxide, carbonization with large shrinkage due to volatilization dispersion loss during firing of raw pitch coke, compatibility of binder with aggregate, calcined coke Focusing on the firing stability of graphite powder, etc.
Raw pitch coke powder having a volatile content of 5 to 20% by weight at 250 μm, or an average particle diameter of 1 in the raw pitch coke.
To a mixture of calcined coke having a size of 0 to 250 μm and carbon aggregate such as artificial graphite, a synthetic resin binder such as coal pitch, petroleum pitch or phenol resin, furan resin, polyethylene resin was added. It has been found that the carbon compact obtained from the composition has high strength and high density, and has completed the present invention. The object of the present invention is to produce a high density and high strength carbon compact, for example, a carbon electrode. The present invention provides a composition for a carbon molded body.

[0004]

Means for Solving the Problems The gist of the present invention is to provide a raw pitch coke powder alone having an average particle diameter of 1 to 250 μm and a volatile content of 5 to 20% by weight, or to the raw pitch coke powder. A composition for a carbon molded body obtained by adding a binder to a mixture of calcined coke having an average particle diameter of 10 to 250 μm, artificial graphite, carbon black alone or a carbon aggregate containing a mixture thereof. is there.

That is, the present invention uses the raw pitch coke powder having the above-mentioned specific properties or a mixture of the raw pitch coke powder and the carbon aggregate having the specific dimensions during firing of the raw pitch coke. In order to improve the moderate shrinkage due to volatilization and dispersion, and to improve the compatibility with the binder, at the same time the firing stability of calcined coke and artificial graphite is added,
As a result, when the composition of the present invention is kneaded, crushed and molded, fired, and further, if it is manufactured according to the usual carbon electrode manufacturing process of graphitizing, a high strength and high density carbon electrode is obtained. It succeeded in getting it easily.

The present invention will be described in more detail. The raw pitch coke used in the present invention is produced by heating a coal recovered by high temperature carbonization of coal to a coking temperature (about 300 to 500 ° C.) with a delayed coker. However, it has a low ash content, is rich in aromatic carbon compounds, and is preferable as a substance forming a graphite structure.

In the present invention, the raw pitch coke having an average grain diameter of 1 to 250 μm, preferably 1 to 45 μm is used. The average grain diameter of raw pitch coke is 1 μm
The reason for the above is that when the molding raw material is pressed into the submicron area, most of the air contained in the raw material is trapped inside the molded body, and partial stress concentration due to air pressure occurs in the subsequent firing process. This is to avoid it.
The reason for setting the thickness to 250 μm or less is that if the thickness is more than 250 μm, uniform contraction of the tissue is hindered, and a high density and high strength cannot be obtained.

The volatile content of the raw pitch coke used in the present invention has an important effect on the carbon electrode after firing. That is, the synergistic action between the carbon aggregate and the binder is exhibited only when there is a large shrinkage phenomenon due to the dissipation of volatile components during firing of the raw pitch coke, and the shrinkage phenomenon is expected only by the binder. Higher density and higher strength can be ensured compared to conventional carbon materials. Therefore, it is preferable that the volatile content during firing of the raw pitch coke is large, but if the volatile content of the raw pitch coke is 20% by weight or more, it becomes difficult to set appropriate firing conditions, and firing cracks occur. The rate at which the
When the content is less than or equal to wt%, the range of firing conditions becomes wider, but the amount of shrinkage is not sufficient and the expected high density and high strength cannot be achieved. Therefore, in the present invention, by setting the volatile content to 5 to 20% by weight, preferably 10 to 15% by weight, it is possible to stably obtain the desired high-density and high-strength carbon material. ..

The binder used in the present invention may be any binder which is usually used for molding a carbon material.
Lupine, petroleum pitch or synthetic resin binders such as phenolic resin, furan resin, polyethylene resin, etc. are not particularly limited, but a coal obtained by carbonization of coal at high temperature is prepared as a binder. A court pitch is preferred.
That is, when coal is carbonized at a high temperature, most of the ash remains in the coal coke, and the recovered coal hardly contains ash. Therefore, this is a co-prepared binder.
This is because the tar pitch has a low ash content and is rich in aromatic carbon compounds which are preferable as a substance forming a graphite structure.

The coke obtained from the coulter is calcined by a calcineer to obtain a calcined pitch coke. Therefore, the pitch of the corner,
Both the raw pitch coke and the calcined pitch coke show very similar structures.

During the heating and mixing process in which the raw pitch coke and the calcined pitch coke are mixed with the coulter pitch, the familiarity at the boundary surface between the fine coke particles and the binder pitch is an aromatic carbon compound. It is much better than the case of raw petroleum coke with a low content of. In other words, the aromatic carbon compound in the raw pitch coke distills during kneading or firing, that is, a mutual compatibility occurs, the bond at the boundary surface of each particle becomes strong, and a certain level is required for strengthening. Although it is effective, it is considered that a high density and high strength carbon molded body can be obtained even if the amount of addition of the coal pitch having a large side effect in terms of easiness of firing and pore distribution is reduced.

Further, in the present invention, carbon aggregate having an average particle diameter of 10 to 250 μm may be added if necessary.
The carbon aggregate is a calcined coke, artificial graphite, carbon black or the like, or a mixture thereof, and the average particle diameter thereof is 10 to 250 μm, preferably 1
It is in the range of 0 to 120 μm. Average grain diameter is 10
If it is less than μm, it is necessary to drastically increase the amount of the binder added, and if it is more than 250 μm, uniform shrinkage of the tissue is not ensured, which is not preferable.

(Function) The compatibility between the carbon aggregate of the present invention and the binder will be discussed in more detail below. That is, conventionally, a value called β resin, which is an aromatic carbon compound contained in a binder such as coal pitch, has been adopted as a standard for measuring the degree of binding action between the carbon aggregate and the binder. Specifically, it has been performed to roughly predict various physical properties of the final carbon molded body based on the content of β resin contained in the binder. However, it is a correlator
It did not come out of the range of binders such as lupitch.

The β-resin is a complex and many kinds of organic compounds contained in pitches, and its exact chemical structure has not been identified yet. However, qualitatively, the so-called benzene-insoluble matter (B
Not extracted with quinoline from percent of I),
It is quantified by the difference in percent of so-called quinoline insoluble matter (QI).

A conventional carbon molded body has a high density and a high strength of the carbon molded body in pursuit of only the function and effect of increasing the carbon yield by the aromatic carbon compound containing only a binder such as a coal pitch. Have been trying to Therefore, about 1300 as an aggregate
Even if only the calcined pitch coke treated at 1400 ° C. is used, the aromatic carbon compound is already decomposed during coking and its effect cannot be expected.

However, when the raw pitch coke treated at about 300 ° C. to 500 ° C. is used as an aggregate, for example, an aromatic carbon compound (β resin) contained in the corn pitch and a raw filler as filler are used. The aromatic carbon compound (β resin) contained in the pitch coke is about 200 ° C to 30 ° C.
During the process of kneading at 0 ° C or the process of heating up to about 1000 ° C, aromatic carbon compounds undergo a polycondensation reaction with each other at the aggregate-binder interface to form giant aromatic molecules. To carbonize. This series of processes is the meaning of compatibility. This makes it possible to produce a precursor state in which the final treatment facilitates the formation of a graphite structure having a hexagonal network-bonded layered structure.

As a result, as compared with the conventional calcinated coke binder-based carbon molded product and the crude petroleum coke binder-based carbon molded product having a relatively large amount of aliphatic carbon compounds, the aggregate and the binder are less likely to be mixed. Thus, it is possible to obtain a high-density, high-strength carbon molded product having a strong interfacial bond in the binder portion.

The carbon electrode obtained from the composition for moldings of the present invention is used for electrical discharge machining, gouging, blasting,
It can be used for various purposes such as movies, lighting and medical purposes.

[0019]

EXAMPLES Examples of the present invention will be described below. Example 1 To 100 parts by weight of a raw pitch coke having an average particle diameter of 1 μm and a volatile content of 6% by weight, 29 parts by weight of a pitch of a coal tar was added and kneaded in a kneader at 210 ° C. for 2 hours. This kneaded material was extruded by a conventional method, molded, and graphitized to obtain an electrode material. The apparent specific gravity, resistance, and electrical specific resistance of the electrode material thus obtained were determined. Further, using the electrode material thus obtained, a carbon electrode for electric discharge machining having an outer diameter of 20 mm and an inner diameter of 5 mm was prepared, and an electric discharge machining test was conducted to measure the length wear rate (%) of the electrode.

The electric discharge machining conditions are: electrode polarity +, electric discharge peak current 5A, on pulse width = 60 μsec, off pulse width =
60 μsec, electric discharge machining oil is 0.05 kg from the center of the electrode
It was ejected at a pressure of / cm ² to process SKD-11 as a workpiece to 1 mm. In addition to this, a gouging electrode having a diameter of 8 mm was prepared using the obtained electrode material and a gouging test was conducted, and the length wear rate of the gouging electrode obtained with the electrode material shown in Comparative Example was set to 100%. The length consumption rate (%) was measured. The test conditions are a current of 300 A and a gouging spin.
The iron base material was processed into a groove depth of 5 mm and a groove width of 10 mm at 900 mm / min. The obtained measured values are shown in Table 1.

Example 2 A raw pitch core having an average grain diameter of 20 μm and a volatile content of 12% by weight.
An electrode material was obtained in the same manner as in Example 1 by adding 22 parts by weight of the pitch of the roller to 100 parts by weight of the wax, and various characteristics were measured in the same manner. The values are shown in Table 1.

Example 3 An electrode material was obtained in the same manner as in Example 1 except that 20 parts by weight of the pitch of the coal tar was added to 100 parts by weight of the raw pitch coke having an average particle diameter of 250 μm and a volatile content of 10% by weight. Thus, various characteristics were measured. The values are shown in Table 1.

Example 4 65 parts by weight of raw pitch coke having an average particle diameter of 2 μm and a volatile content of 10% by weight was added to 65 parts by weight of a pitch coke having an average particle diameter of 2 μm.
An electrode material was obtained in the same manner as in Example 1 by adding 35 parts by weight of the pitch to the compound containing 1 part by weight, and various properties were measured in the same manner. The values are shown in Table 1.

Example 5 Raw pitch core having an average grain diameter of 20 μm and a volatile content of 15% by weight
30 parts by weight of the coal pitch were added to a mixture of 65 parts by weight of the coke and 35 parts by weight of the pitch coke having an average particle diameter of 20 μm to obtain an electrode material in the same manner as in Example 1. The properties were measured. The values are shown in Table 1.

Example 6 A pitch coke having an average grain diameter of 110 μm and 30 parts by weight of a raw pitch coke having an average grain diameter of 110 μm and a volatile content of 20% by weight was used.
A mixture containing 70 parts by weight of coke
An electrode material was obtained in the same manner as in Example 1 by adding 7 parts by weight, and various characteristics were measured in the same manner. The values are shown in Table 1.

Example 7 Pitch coke 70 having an average particle diameter of 2 μm and 15 parts by weight of a raw pitch coke having an average particle diameter of 2 μm and a volatile content of 10% by weight.
40 parts by weight of the coulter rubite was added to a mixture containing 1 part by weight and 15 parts by weight of carbon black, an electrode material was obtained in the same manner as in Example 1, and various characteristics were measured in the same manner. The values are shown in Table 1.

COMPARATIVE EXAMPLE An electrode material was obtained in the same manner as in Example 1 by adding 60 parts by weight of the pitch of the pitch to 100 parts by weight of the pitch coke having an average particle diameter of 20 μm, and various characteristics were measured in the same manner. The values are shown in Table 1.

[0028]

[Table 1]

[0029]

As is clear from the above results, the carbon material for electrode material obtained from the composition of the present invention is a viscous compound such as an aromatic carbon compound peculiar to raw pitch coke and a coral pitch. It is considered that the bonding strength between the fillers was dramatically improved by the polycondensation reaction at the binder interface, and at the same time the apparent specific gravity increased due to the shrinking action due to the volatilization dispersion loss during firing, which is peculiar to raw coke. A high-strength electrode material was obtained.

As a result, it was possible to obtain a carbon electrode for electric discharge machining, an electrode for gouging, etc., which is far less likely to wear than conventional carbon electrodes for electric discharge machining, electrodes for gouging and the like.

Claims (1)

[Claims] 1. An average particle diameter of 1 to 250 μm and a volatile content of 5
20% by weight raw pitch coke powder alone, or the raw pitch coke powder and calcined coke having an average particle diameter of 10 to 250 μm, artificial graphite, carbon black alone or a mixture thereof. A composition for a carbon molded body, which is obtained by adding a binder to a mixture containing the carbon aggregate.