KR101601401B1 - A method of producing graphite material - Google Patents

Abstract

The present invention provides a production method in which a high-density and high-strength graphite material is obtained by using a finely pulverized raw material coke, and is hardly ignited and ignited.
A method for producing a graphite material includes a first step of adding a binder pitch to a coke powder and kneading it in a closed space to form an aggregate of coke powder and a step of kneading the aggregate of the coke powder while introducing air or oxygen, And a second step of obtaining a kneaded product by condensing the binder pitch constituting the aggregate; a crushing step of crushing the kneaded product to obtain a crushed raw material; a molding step of molding the crushed raw material to obtain a molded product; A firing step of firing to obtain a fired body, and a graphitization step of obtaining a graphite material by graphitizing the fired body.

Description

METHOD OF PRODUCING GRAPHITE MATERIAL BACKGROUND OF THE INVENTION [0001]

The present invention relates to a graphite material and a method for producing the same.

Graphite materials are used in various industrial fields such as members for a silicon single crystal pulling device, electrodes for electric discharge machining, molds for polycrystalline silicon used for solar cells, and hot press members. Such a graphite material is generally known to be produced according to the following processes (1) to (5).

(1) A kneading step of obtaining a kneaded product of pitch and coke

(2) a pulverizing step of pulverizing the kneaded material to obtain a molding material

(3) a molding process for obtaining a compact by molding a raw material for pulverization

(4) a firing step of heating the formed body to remove volatile components to obtain a fired body

(5) a graphitizing step of subjecting the fired body to a heat treatment at a higher temperature than the firing step,

The raw material coke, which is an aggregate of graphite material, is a material obtained by caulking a pitch. The raw material coke is a porous raw material which generates pyrolysis gas from the pitch of the raw material at the time of production and has a large amount of pores therein. Since the graphite material uses coke containing a large amount of pores as a raw material, it is difficult to obtain a high-density material.

As a result, a graphite material having a higher strength and a higher density can be obtained by finely pulverizing the coke as an aggregate. It depends on the following reasons.

(1) High-density graphite material is obtained by finely pulverizing aggregate to reduce pores contained in the raw material coke itself.

(2) The finely pulverized raw material coke is combined with a binder to form a delicate structure, whereby the pore size is reduced to obtain a high-strength graphite material.

Such a graphite material is a porous material having a delicate structure because it is obtained by pulverizing a kneaded product obtained by kneading a coke powder obtained by pulverizing a raw material coke with a binder and molding, firing and graphitizing.

Since the coke powder molecular sieve, which is a raw material of the graphite material, has a weak bonding force, the pitch serves to bind the coke powder. Particularly, calcined cokes which contain little organic components (volatile matter) have little bonding strength. On the other hand, since the pitch is melted and the raw material coke is bonded and carbonized as it is, the raw material coke can be connected to each other. When carbonized, a part of the pitch is pyrolyzed and decomposed gas is vaporized. If the addition amount of the pitch is too small, the function as a binder is insufficient, and it is difficult to obtain a high-density and high-strength graphite material. On the other hand, if the addition amount of the pitch is too large, a large amount of decomposition gas is generated to increase the pores of the carbon material, which makes it difficult to obtain a high-density and high-strength graphite material and also causes internal cracks and the like.

In order to obtain a high-density and high-strength graphite material, Patent Document 1 discloses a technique in which a coal tar pitch is added to a combination of raw pitch coke having an average particle diameter of 15 micrometers or less and calcined pitch coke having an average particle diameter of 44 micrometers or less A composition for a special carbon material (graphite material) characterized by having a raw pitch coke amount of not less than 40 parts by weight among 100 parts by weight of a composition containing the fresh pitch coke and the calcined pitch coke, .

Specifically, in the manufacturing method of this document, by using raw pitch coke and calcined pitch coke as main raw materials for special carbon materials, it is possible to improve compatibility between fine particles of both raw materials and coal tar pitch, And particularly high strength and high density and a high purity special carbon material which can not be obtained with a conventional raw petroleum coke and calcined coke raw material by further improving the uniformity of the raw petroleum coke and the calcined coke.

Further, in the production method described in Patent Document 1, raw material cokes containing volatile components such as raw pitch coke and having aggregate itself are used, so that it is possible to reduce the addition amount of the binder that easily forms pores by generating decomposed gas And a high density and high strength graphite material can be obtained.

Japanese Patent Application Laid-open No. 4-228412

However, raw material coke is a combustible material, as is known from the dust explosion of pulverized coal. As the raw material coke is finely pulverized and the medic glasses become smaller, the specific surface area becomes larger, the chemical reactivity becomes higher, and the reaction with oxygen or the like is easy. Particularly, raw coke containing volatile matter has a particularly high chemical reactivity and is liable to react with oxygen or the like.

When such a finely pulverized coke powder is added to a heated kneading apparatus and kneaded while heating, the coke powder and oxygen may combine to cause ignition. Particularly, in a heated kneading apparatus, even if there is no ignition source, the heated coke itself may be ignited as a ignition source. Especially when raw coke is used as a raw material, ignition and ignition tend to occur.

In addition, a raw coke having strong volatility and high volatility requires a special crushing device such as crushing in a nitrogen atmosphere so that it is easy to ignite even in the previous crushing process and is not ignited in crushing raw coke having high volatile content.

For this reason, if fine-grained raw material coke having a high volatile content is used in order to obtain a fine-grained high-density and high-strength graphite material, there is a risk that the raw material is easily ignited.

In the present invention, it is intended to provide a production method in which a high-density and high-strength graphite material can be obtained by using fine pulverized raw material coke, and ignition and ignition are difficult.

(1) A method for producing a graphite material according to the present invention is characterized by comprising a first step of adding a binder pitch to a coke powder and kneading the mixture in a closed space to form an aggregate of coke powder, And a second step of kneading the mixture to obtain a kneaded product by condensing the binder pitch constituting the aggregate of coke components; a crushing step of crushing the kneaded product to obtain a crushed raw material; A firing step of firing the formed body to obtain a fired body, and a graphitization step of obtaining a graphite material by graphitizing the fired body.

(2) It is a mode of the present invention. For example, the first step is performed under a temperature environment equal to or higher than the softening point of the binder pitch.

(3) It is a mode of the present invention. For example, in the second step, the temperature of the aggregate of coke is higher than the temperature of the inner wall of the kneading apparatus.

(4) It is a mode of the present invention, for example, that the rate of temperature rise of the aggregate of coke fractions increases discontinuously at the boundary between the first step and the second step.

According to the present invention, the kneading step includes a first step of adding a binder pitch to the coke powder and kneading it in a closed space to form an aggregate of the coke powder, and a step of kneading the aggregate of the coke powder while introducing air or oxygen, And a second step of obtaining a kneaded product by condensing the binder pitch constituting the aggregate of the aggregates. Therefore, in the first step, the aggregate of coke components is formed by adding the binder pitch to the coke component having a small median glasses and a large specific surface area. Therefore, the coke component having a small median glasses and a large specific surface area can be produced can do. Therefore, high-density and high-strength graphite materials having a fine structure can be formed without ignition.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing a manufacturing process of a method for producing a graphite material according to an embodiment of the present invention. Fig.
2 is a schematic diagram showing a kneading step of a method for producing a graphite material according to an embodiment of the present invention.
3 is a graph of the temperature of the contents of the kneading apparatus in the embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In the present specification, the medi-spectacle means a 50% volume cumulative diameter and a diameter refers to a diameter.

In the present specification, the term " cohesion " is used in particular for coal and carbon-based materials, and indicates a property of being carbonized through the softened state.

In the present specification, " binder pitch " is included in " pitch ". Binder pitch refers to the pitch used for the purpose of addition at the time of kneading and mixing. In addition, the pitch has impregnation pitch used for impregnation. Even if it is impregnated pitch or binder pitch, the same pitch can be used.

The method for producing the graphite material of the present embodiment basically includes the following steps (a) to (e).

(a) a first step of adding a binder pitch to a coke powder and kneading it in a closed space to form an aggregate of coke powder, and a step of kneading the aggregate of coke powder while introducing air or oxygen to form an aggregate of coke powder And a second step of condensing the binder pitch to obtain a kneaded product

(b) a pulverizing step of pulverizing the kneaded material to obtain a pulverization raw material

(c) a shaping step of forming a compact by molding the pulverization raw material

(d) a firing step of firing the formed body to obtain a fired body

(e) a graphitization step of graphitizing the sintered body to obtain a graphite material

Fig. 1 shows a flow chart of the manufacturing process of the graphite material manufacturing method according to one embodiment of the present invention. Fig. 2 shows the kneading process of the graphite material manufacturing method according to one embodiment of the present invention in detail do.

The kneading step in the production method of this embodiment shown in Fig. 2 will be described below. The contents described in Fig. 2 correspond to S1 in Fig.

Fig. 2 (A) shows the coke 11. Fig. The coke 11 has large pores 11a formed mainly by caulking shrinkage in the interior of the cokes 11 instead of the layered crystals being developed. Fig. 2 (B) shows the coke powder 12 obtained by crushing the coke 11. As shown in Fig. The large pores 11a in the coke shown in Fig. 2 (A) are lost by finely grinding. Fig. 2 (C) shows the aggregate 13 of coke fractions formed by adding the binder pitch 1 to the coke fractions 12.

2 (D) shows a kneading body 14 obtained by kneading air or oxygen into an aggregate 13 of coke powder. The binder pitch 1 is condensed to firmly bind the coke powder to the kneaded mixture.

Hereinafter, the kneading step in the method for producing a graphite material of the present invention will be described with reference to the drawings.

In the first step of the kneading process in the present invention, the binder pitch 1 is first added to the coke powder and the coke powder 12 is kneaded in the closed space to form an aggregate 13 of coke powder. In the stage where the coke powder is present, the small coke powder 12 which is finely pulverized and has a small median glasses tends to be ignited because of its large specific surface area. However, once the coke powder aggregate 13 is formed, the specific surface area becomes small, It is possible to make it difficult to be ignited because it contains the binder pitch 1 in which a latent heat of vaporization is required (Fig. 2 (C)).

In the second stage of the kneading process, kneading is performed while introducing air or oxygen into the resulting aggregate (13) of coke powder to obtain a kneaded product (14). When this step is completed, the binder pitch 1 applied to the coke powder 12 is undergoing condensation (FIG. 2 (D)).

In the present invention, since air or oxygen is introduced in the kneading step, hydrogen is easily extracted from the binder pitch contained in the kneaded product, and the condensation reaction of the binder pitch is promoted. Therefore, it is considered that the condensation of the binder pitch progresses faster than the rate at which the low molecular weight component of the binder pitch is volatilized, and the coke is firmly connected to obtain a dense graphite material. Further, in the kneading step, in the first step, the coke powder 12 becomes the aggregate 13 of coke powder, has a small specific surface area and is difficult to be ignited, and has a delicate structure. By accelerating the condensation of the binder pitch 1 in the second step, volatilization is adjusted and added to give tackiness, so that the moldability is improved, the degree of cohesion is increased, and a high-density and high-strength graphite material is obtained.

In contrast, in the conventional method for producing a graphite material, the binder pitch 1 is added to the coke powder 12 without introducing air or oxygen to form the kneading body 14. Therefore, it is considered that the binder pitch is not sufficiently condensed and the low molecular weight component is easily volatilized. Therefore, it is considered that the coke can not be firmly connected to each other and it becomes difficult to obtain a high-density and high-strength graphite material.

The method of producing the graphite material of the present embodiment will be described in detail below step by step.

≪ Explanation of the kneading process; In step S1 of Fig. 1,

In the present embodiment, the closed space refers to a space surrounded by the surroundings. Concretely, for example, it indicates an environment in which the diffusion of the gas is restricted, such as a state in which the lid is covered with the kneading apparatus, and airtightness is not required. In the environment where diffusion of the gas is restricted, such as a state in which the kneading apparatus is covered with the cap, inflow of air and oxygen from the outside is limited, so that the oxygen concentration can be kept low and it is difficult to ignite the coke powder or raw coke can do.

In the present invention, introducing air or oxygen may be any method. Blower air or oxygen may be sent from the outside or air or oxygen may be introduced from the outside by sucking the decomposition gas of the binder pitch generated in the kneading apparatus.

The raw material of the coke powder of the present invention is not particularly limited. Petroleum coke, coal coke and their raw coke, calcined coke, and the like. These cokes are finely pulverized to obtain coke fractions. The medicines of coke are not particularly limited, but coke powder pulverized to 3 to 15 mu m can be used, for example.

Since the fine pulverized coke powder has a large specific surface area, when it is heated, it reacts with oxygen contained in the atmosphere and is easily oxidized. Since the coke oven has little or no volatile components, it can be easily heated without depriving the heat of vaporization, and once the reaction starts, the temperature rises rapidly to ignite or ignite.

The method for producing a graphite material of the present embodiment is characterized in that, in the first step, the coke powder and the binder pitch are kneaded in the closed space to bond the coke powder to each other at a pitch to reduce the specific surface area, At the same time, it is difficult to be heated by adding a volatile component.

Subsequently, by introducing air or oxygen in the second step, the volatiles contained in the binder pitch can be gradually evaporated while the heat is taken away. In addition, oxygen has an action of condensing the binder pitch and has an action of promoting the caking of the binder pitch. The condensation of the binder pitch can be promoted by kneading the aggregate of coke components while introducing air or oxygen. And a kneading step of forming an aggregate of coke components by binding by binder pitch and heating and kneading the coke components having a large specific surface area without contacting with oxygen to form a kneaded product having strong pointing force .

Further, the binder pitch may be added in the middle of the second step. The following effects can be expected by further adding the binder pitch in the middle of the second step.

The binder pitch applied at the beginning of the kneading step progresses while introducing air or oxygen in the second step. It is considered that the binder pitch in which the condensation proceeds is less in the low molecular weight component having adhesive force, so that the adhesive force of the pulverization raw material including the binder pitch in which the condensation proceeds in the subsequent molding step is lowered and the formability is deteriorated. When the moldability is deteriorated, the strength of the molded body is lowered, and the molded body is easily broken. Therefore, by adding the binder pitch in the middle of the second step, it is possible to add a low-molecular-weight component having adhesive force to make the molded article difficult to break.

If the amount of the binder pitch to be added in the middle of the second step is excessively added, a large aggregate of the coke components in the kneading step is formed and it becomes difficult to knead. Further, when a large amount of binder pitch is added in the middle of the second step, a large amount of decomposition gas is generated from the binder pitch added in the subsequent firing step, and the pores of the carbon material are increased, so that the high- Which is not only difficult to obtain but also causes internal cracks and the like. Therefore, it is preferable that the amount of the binder pitch added in the second step of the kneading step is smaller than the amount of the binder pitch applied at the beginning of the kneading step.

When the binder pitch is further added during the second step, it is preferable that the amount of the binder pitch to be added in the middle of the second step is 15 to 25% of the amount of the binder pitch applied at the beginning of the kneading step. If the amount of the binder pitch added during the second step exceeds 25% of the amount of the binder pitch applied at the beginning of the kneading step, a large excess of binder pitch remains on the surface of the aggregate of coke components, A large agglomerate of the aggregate of agglomerates is formed and it becomes difficult to knead. If the amount of the binder pitch added during the second step exceeds 25% of the amount of the binder pitch initially applied in the kneading step, a large amount of decomposition gas is generated from the binder pitch added during the second step in the firing step The pores of the carbon material increase, and it is not only difficult to obtain a high-density and high-strength graphite material, but also easily induces internal cracks. If the amount of the binder pitch added during the second step is 15% or more of the amount of the binder pitch applied at the beginning of the kneading step, sufficient cohesion can be imparted to the kneaded material formed in the kneading step, Can be obtained.

The binder pitch used in the kneading step is not particularly limited. For example, a petroleum pitch, a coal pitch, or the like can be used, but it is preferable to use coal pitch. Since the coal-based pitch contains a large amount of aromatic rings, it has a good affinity with the carbonized coke, can form an aggregate of the coke powder quickly, and has a high effect of preventing ignition of the coke powder.

The softening point of the binder pitch used in the kneading step is not particularly limited, but it is preferable to use a pitch of 60 to 100 캜. When the softening point is 60 deg. C or higher, the raw coke can be efficiently produced because the hydrocarbon yield is high. When the softening point is 100 DEG C or lower, the coke can be rapidly melted. Therefore, an aggregate of the coke powder can be formed rapidly and the effect of preventing ignition of the coke powder is high.

≪ Explanation of Crushing Process > Step S2 of Fig. 1>

In the pulverization step of the present invention, the kneaded material containing the coke fraction and the binder pitch is pulverized. As described below, the medicament glasses of the pulverization raw material are preferably larger than the medicinal glasses of the coke of the starting material, and more preferably 150% or more of the medicinal glasses of the cokes. In the pulverizing step, the soft part of the kneaded product is pulverized.

The kneading body includes a binder pitch and a coke component added in the kneading step. Compared to the binder pitch, the coke powder is hard and hard to be crushed. The degree of cohesion is smaller in the coke part than in the binder pitch. When the medicament glasses of the raw material for pulverization are crushed so as to become smaller than the medic glasses of the coke, the fracture surfaces of the coke fractions having no cohesion are exposed because they function to make the coke fractions finer. The medic glasses of the raw material for pulverization are preferably made larger than the medic glasses of the coke so as not to expose the fracture surface of the coke powder having no cohesion and the medicines of the pulverization raw material are preferably coke- Of the median glasses of the present invention.

The crushing process of the present invention may be any crusher, but is not particularly limited. A pin mill, a hammer mill, or the like.

≪ Description of forming process; Step S3 of Fig. 1>

No particular limitation is imposed on the molding process of the present invention. For example, it can be used in any method such as stamping molding and CIP (Cold Isostatic Press) molding. The molding pressure is not particularly limited. For example, at a molding pressure of 20 to 5000 MPa. In the stamping molding, the pressing is performed in the uniaxial direction, and the particles of the flat pulverization raw material tend to be arranged in a plane orthogonal to the pressing direction, so that the directionality is easily formed. In CIP molding, It is possible to obtain a graphite material which is difficult to be formed (small anisotropy). Therefore, it is preferable to perform the CIP molding.

Explanation of the firing process; Step S4 of Fig. 1 >

Any of the firing processes of the present invention can be used. For example, an electric furnace, a furnace, or the like. The firing step is a step for heating the molded body or the fired body similarly to the subsequent graphitization step. In the firing step, it is desirable to sufficiently remove the volatile components of the molded body so as not to break in the subsequent graphitization step, and it is preferable that the amount of volatile matter can be largely removed and the rate of temperature rise is slow enough not to cause fracture of the molded body. The preferred treatment temperature is 800 to 1500 占 폚. If the treatment temperature is 800 DEG C or higher, carbonization of the formed body is sufficiently performed, so that thermal shock applied to the molded body can be reduced even after rapid heating in the subsequent graphitization step, making it difficult to break. The decomposition gas generated from the compact substantially converges up to 1500 DEG C, so even if calcination is carried out at a temperature exceeding 1500 DEG C, it hardly affects the fragility of the graphitization process. Since the thermal energy is useless even at a temperature exceeding 1500 캜, it is preferable to be fired at a treatment temperature of 1500 캜 or lower.

The rate of temperature rise when the formed body is baked can be set appropriately in accordance with the temperature difference generated inside the formed body. For example, if the molded body has a size of 200 x 100 x 30 mm, it can be fired at a heating rate of 20 ° C / hr or less. For example, if the molded body has a size of 1000 x 500 x 300 mm, It can be fired.

≪ Description of Graphitization Process > Step S5 of Fig. 1 >

Any method can be used for the graphitization process of the present invention. Etchers, induction furnaces, and the like. The graphitization can appropriately set the treatment temperature according to the application, and can be graphitized at a treatment temperature of, for example, 2000 to 3200 ° C.

<Others>

The first step of the kneading step is preferably carried out under a temperature environment equal to or higher than the softening point of the binder pitch. In the first stage of the kneading process, the coke is mixed with the pitch in the closed space to which no air or oxygen is supplied to reduce the specific surface area of the coke powder, and the pitch having the latent heat of vaporization is mixed (kneaded) It is aimed to adjust the raw material which is hard to cause rapid oxidation reaction. In order for the step of forming the aggregate of coke components to be carried out quickly, it is preferable that the step is performed under a temperature environment equal to or higher than the softening point of the binder pitch. Temperature environment above the softening point of the binder pitch Since the binder pitch on the high side is present in the liquid phase, the time to mixing can be shortened without requiring a mechanical frictional force. By shortening the time until mixing, the contact time with air or oxygen remaining in the kneading apparatus can be shortened, so that the coke powder can be hardly ignited. The inner wall temperature of the kneading apparatus in the first stage of the preferable kneading step is 150 to 300 캜, which is a temperature equal to or higher than the softening point of the binder pitch to be used. 150 캜, the binder pitch can be sufficiently softened, and the mixing time can be shortened. If the temperature is lower than 300 DEG C, the binder pitch can be slowly heated, so that particulate raw coke can be formed by the interaction of the friction force and heat of the kneading apparatus as described later. The inner wall temperature of the kneading apparatus refers to the temperature at the portion of the inner wall of the kneading apparatus where the contents contact.

It is preferable that the maximum temperature of the aggregate of coke components is higher than the inner wall temperature of the kneading apparatus. The binder pitch contained in the aggregates of the coke components reacts with oxygen to be condensed and generates heat so as to emit frictional heat at the rotation of the impeller (blade) of the kneading apparatus and to be higher than the inner wall temperature of the kneading apparatus.

The maximum temperature of the aggregate of the coke powder refers to the maximum temperature reached when the temperature of the aggregate of the coke powder is kneaded by the kneading apparatus and gradually changes over time. The softening point of the binder pitch can be measured by the ring method of JIS K2425-2006.

At the boundary between the first step and the second step, it is preferable that the rate of temperature rise of the aggregate of coke components increase discontinuously. In the first step, the temperature of the aggregate of coke components increases with the frictional heat imparted from the impeller. In the second step, the temperature of the aggregate of coke components increases due to the heat of friction between the impeller and the binder pitch. As a result, the rate of temperature rise of the aggregate of coke components is discontinuously increased by introducing air or oxygen.

Non-continuous increase means that the rising speed has a stepwise change before and after. At the boundary between the first step and the second step, it is possible to accelerate the condensation of the binder pitch by supplying sufficient air or oxygen so that the rate of temperature rise of the aggregate of coke components increases discontinuously.

In the second step of the kneading step, a manufacturing method in the case where the binder pitch is further added is described below.

In the second step of the kneading step, it is preferable to add the binder pitch to the step in which the aggregate of coke particles becomes a particulate phase. In the kneading step, first, the mechanical friction force of the kneading apparatus (kneader) acts, and the binder pitch applied at the beginning of the kneading step is kneaded. When air or oxygen is transferred to the second step, the binder pitch is pyrolyzed by the action of oxygen in the heat and the atmosphere over time, and the degree of polymerization is increased. Along with pyrolysis of the binder pitch, the mixture of the coke powder and the binder pitch is changed into a granular phase of about 1 to 30 mm from the wet powder phase (wet powder phase). The mixture of the coke component in the wet state and the binder pitch receives friction force and heat between the impeller and the wall surface of the kneading apparatus to promote the condensation of the binder pitch. As the condensation of the pitch progresses, it is changed into a particulate phase of about 1 to 30 mm. Therefore, even when it is sandwiched between the impeller and the wall surface of the kneading apparatus, it also acts to roll, and it becomes difficult to receive frictional force and heat. Further, the large particles are not sandwiched between the impeller and the wall surface of the kneading apparatus, and frictional force and heat are hardly received. Therefore, the progress of the condensation of the binder pitch is slowed at the stage where the mixture of the coke powder and the binder pitch becomes granular. Further, when the kneading is continued, the condensation of the binder pitch proceeds little by little, and the particles become hard and the surface of the particles is polished little by little to generate powder. It is preferable to further add the binder pitch to the stage at which the powder starts to be generated at the latest. When the powder starts to be formed, the specific surface area of the aggregate of the coke powder is largely changed, so that the amount of the additional binder pitch required is unstable, the strength and density of the obtained graphite material become unstable, and a high-strength and high- It becomes difficult to become.

The binder pitch to be added in the middle of the second step may be the same as or different from the binder pitch applied at the beginning of the kneading step. For example, a petroleum pitch, a coal pitch, or the like may be used. If the binder pitch added in the middle of the second step and the binder pitch applied at the beginning of the kneading step are the same, the graphite material structure formed by carbonizing the pitch has a similar degree of impurity and crystallinity, so that a homogeneous graphite material can be obtained, It is considered that a graphite material with a high strength is obtained. The softening point of the binder pitch used in the kneading forming step is not particularly limited. For example, a pitch having a softening point of 60 to 100 DEG C can be used.

Hereinafter, examples and comparative examples of the present invention will be described in order. The temperature of the contents of the kneading apparatus in the embodiment will be described with reference to Fig.

[Example]

<Kneading Process>

As the kneading apparatus, a pair-finished kneader was used. A jacket is provided on the wall surface and the bottom surface of the twinned kneader, and the jacket is filled with the heat medium oil, and the temperature is controlled by the heater inside. The kneading portion of the twinned kneader has an opening at the top, but the kneading portion can be closed by covering the opening with the cover. By covering the opening with a lid, movement of the kneading portion and the outside gas can be restricted. The upper portion of the twinned kneader has an exhaust pipe connected to the blower and a suction pipe connected to the outside air. The suction pipe has a shut-off valve, and air can be introduced from the suction pipe by sucking the gas in the kneading device with the blower when the shut-off valve is released. The inner wall temperature of the kneading apparatus is measured by a thermocouple provided at the bottom where the contents contact.

A kneading step was carried out using as raw materials the calcined coke coke fraction pulverized to median glasses 14 mu m and the solid coal binder pitch having a softening point of 85 DEG C as raw materials.

First, 400 kg of coke and 188 kg of binder pitch were charged into a kneading apparatus (twin-head type kneader) whose inner wall temperature was controlled at 220 캜 by a fruit oil, covered with a lid, closed for 20 minutes, . After the heating, the impeller (blade) of the twinned kneader was rotated, and the compression and shearing action was given between the impeller and the wall surface of the kneading apparatus while mixing the binder with the coke. 32 minutes after the start of rotation of the impeller (point A in Fig. 3), the temperature of the contents (mixture of coke powder and binder pitch) reached 185 캜, which exceeded the melting point of the binder pitch, and the suction of the gas inside was started with the blower. At this point, the contents were wet powder (wet powder). It was confirmed that the rate of temperature rise of the aggregate of coke components contained in the contents was discontinuously increased at the boundary between the first step and the second step (that is, point A) in which the blowing of the gas inside the kneading apparatus was started with the blower. Specifically, the rate of temperature rise immediately before the suction of the gas inside the blower was started was 43 ° C / hour, while the rate of temperature rise immediately after the start of gas suction by the blower was 60 ° C / hour, and 17 ° C / Non - continuous rise of time was seen.

This is because the outside air at room temperature is introduced from the suction pipe and the warmed gas is discharged from the exhaust pipe, so that the temperature in the kneading device is absorbed, It can be seen that the contents are generating heat. This is a reaction between the binder pitch and oxygen, and it can be seen that oxygen is involved in the condensation reaction of the binder pitch.

The load of the motor that rotates the impeller 132 minutes after the start of the suction by the blower, that is, 132 minutes after the start of the rotation of the impeller, decreases (point B in Fig. 3) Began to change. The temperature at this time was 253 ° C. Since the temperature at this time is higher than the temperature of the inner wall of the kneading apparatus, it can be seen that the friction heat and the binder pitch imparted from the impeller and oxygen react to accelerate the condensation reaction and generate heat. The temperature of the aggregate of the coke components is higher than the temperature of the inner wall of the kneading apparatus. The temperature of the contents thereafter is omitted because the content is attached to the thermocouple that thermoclines, and can not be continuously measured.

Further, as the kneading was continued, the contents gradually grew into particulate matter. At the time when 189 minutes elapsed from the start of rotation of the impeller, the content (aggregate of coke particles) was grown in a particle shape having a luster on the surface of about 1 to 20 mm. Therefore, the frictional force can not be sufficiently transmitted to the aggregate of the coke particles that have become granular particles from the impeller, and it is presumed that the temperature of the contents (aggregate of the coke particles) falls.

At this time (after 189 minutes from the start of rotation of the impeller), a further 46 kg of binder pitch was added. When the binder pitch was further added, aggregates of the particulate coke particles adhered to each other to form large lumps. At the same time, a large rotational torque was required for the impeller. Thereafter, the taken-out contents are pulverized in the next pulverizing step as a kneading body.

In the kneading step, the contents were not complexed.

&Lt; Crushing process >

The kneaded product obtained in the above process was pulverized using a pulverizer (pin mill). And pulverized repeatedly with a pulverizer to obtain a pulverization raw material having a median size of 21.2 占 퐉.

&Lt; Molding step &

The raw material for pulverization obtained in the above step was filled in a rubber bag, covered with a lid, sealed, and molded with a CIP molding machine. The pressure of the CIP molding machine was 100 MPa. A molded product of 70 x 150 x 200 mm was obtained by the molding process.

&Lt; Firing step &

The green body obtained in the above step was filled in a fired can, and fired at a treatment temperature of 900 DEG C to obtain a fired body. The rate of temperature rise in the sintering process was 1.3 캜 / hour.

&Lt; Graphitization step &

The sintered body obtained in the above step was filled in a graphite container and heated to 2500 占 폚 using an induction furnace to obtain a graphite material. When the obtained graphite material was cut, a section of a fine and fine structure free of internal cracks or the like was obtained.

Further, a test piece was sampled from the obtained graphite material, and the bulk density and the bending strength were measured. The bulk density was 1.752 g / cm ³ and the bending strength was 45.5 MPa.

[Comparative Example]

A kneading step was carried out using raw coke coke powder of pulverized coal so that the median glasses became 7 占 퐉 and a solid coal pitch having a softening point of 85 占 폚 as raw materials. The raw coke contains 4% moisture and 12% volatile matter. The raw coke itself is susceptible to spontaneous ignition, so that moisture is applied. For this reason, it was dried with a rotary kiln to remove water and pulverized as it was to obtain coke powder. The volatile content can be measured in accordance with JIS M8812.

When kneading was continued while the coke component and the binder were put in the same kneading apparatus as that of the embodiment and the lid was released, the temperature of the contents was increased to ignite the raw coke, and it became glowing and could not be kneaded.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the basis of the claims and specification, Is also intended by the present invention and is included in the scope of seeking protection.

According to the present invention, a high-density and high-strength graphite material having a fine structure can be safely and efficiently formed.

1 Binder pitch
2 Binder Pitch Carbide
11 Coke
11a construction
12 coke minutes
13 Aggregate of coke powder
14 kneading body

Claims (4)

A first step of adding a binder pitch to the coke powder and kneading the mixture in a closed space in which the cover is closed to form an aggregate of coke powder and a step of kneading the aggregate of coke powder while introducing air or oxygen to form an aggregate of coke powder And a second step of condensing the binder pitch to obtain a particulate kneaded product;
A pulverizing step of pulverizing the kneading body to obtain a pulverization raw material,
A shaping step of shaping the pulverization raw material to obtain a compact,
A firing step of firing the formed body to obtain a fired body,
A graphitization step of graphitizing the sintered body to obtain a graphite material
/ RTI &gt;
Wherein the rate of temperature rise of the aggregate of coke fractions at the boundary between the first step and the second step increases discontinuously
A method for producing a graphite material. The method according to claim 1,
Wherein the first step is performed under a temperature environment equal to or higher than the softening point of the binder pitch. delete delete

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