KR102508857B1 - Manufacturing method of carbonized blocks used for manufacturing isotropic graphite - Google Patents

Abstract

The carbonized block manufacturing method for producing isostatic graphite of the present invention includes mixing coke having a D50 of 20 μm or less and binder pitch, kneading the mixture at a final kneading temperature of 250 ° C. or higher, forming the kneaded product; and carbonizing the molded body, wherein in the mixing step, the binder pitch is 30wt% or more based on 100wt% of the mixture.

Description

Carbonized block manufacturing method for isotropic graphite manufacturing {Manufacturing method of carbonized blocks used for manufacturing isotropic graphite}

It relates to a method for producing a carbonized block for producing isostatic graphite. Specifically, it relates to a method for manufacturing a carbonized block used to manufacture isotropic graphite that can be used in crucibles for manufacturing single crystal for semiconductor wafers and polycrystalline Si for solar power, and has important relevance to performance implementation after graphitization.

In general, the production of isotropic graphite material is performed by a method of adding binder pitch to calcined coke powder, mixing, kneading, and pulverizing, pressing and molding, and firing and graphitizing a molded body.

Isotropic graphite materials are used in various other mechanical parts, such as crucibles for manufacturing single crystal for semiconductor wafers or polycrystalline Si for solar power, heating elements, and parts for nuclear power generation.

When it is applied for machining, the smaller the fracture surface of the basic particles that inevitably occur on the machined surface, the more it affects the processability. Toyo Tanso uses a filler with a smaller and more uniform particle size than before, so that microfabrication is possible. product was manufactured (Tanso 2008, 234, 234-243).

It is intended to provide a method for producing a high-density carbide block that can be used for producing isostatic graphite.

A carbonized block manufacturing method for producing isotropic graphite according to an embodiment of the present invention includes mixing coke having a D50 of 20 μm or less and binder pitch, kneading the mixture at a final kneading temperature of 250 ° C. or higher, and molding the kneaded material. and carbonizing the molded body.

In the mixing step, the binder pitch may be 30 wt% or more based on 100 wt% of the mixture.

In the mixing step, the binder pitch may have a heat treatment yield of 50 wt% or more at 500 ° C.

In the kneading step, the volatile matter content of the kneaded product may be 10 wt% or less.

The carbide obtained in the carbonization step may have an apparent density of 1.4 or more.

The carbide obtained in the carbonization step may have a porosity of 25.5% or less.

The binder pitch may have a QI content of 2 wt% or more and a beta-resin content of 20 wt% or more.

The binder pitch may have a QI content of 4 wt% or more and a beta-resin content of 20 wt% or more.

The forming step may be to prepare a molded article by pressurizing the kneaded material in the range of 100 MPa to 280 MPa.

In the mixing step, coke may have a span value of 1.3 or less.

After the kneading, it may further include crushing and screening the kneaded material.

The method for producing isotropic graphite according to an embodiment of the present invention may further include graphitizing the carbide after the carbonizing step.

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According to the manufacturing method of the present invention, the density of the carbonized block for producing isotropic graphite can be improved.

1 is a flowchart illustrating a method of manufacturing a carbonized block for producing isotropic graphite according to an embodiment of the present invention.
Figure 2 shows the density change of the carbonized block according to the pitch content for each kneading final temperature.
3 shows the change in porosity of the carbonized block according to the pitch content for each kneading final temperature.
4 is a result of analyzing the thermal decomposition behavior of binder pitch by TGA.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. When it is said that a certain part "includes" a component throughout the specification, this means that it may further include other components, not excluding other components unless otherwise stated. In addition, singular forms also include plural forms unless specifically stated in the text.

In some embodiments, well-known techniques are not described in detail in order to avoid obscuring the interpretation of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

The present invention provides a method for producing a high-density carbonized block for producing high-density isotropic graphite.

Specifically, by controlling the conditions of each process step, it provides a method for producing a carbonized block with improved density.

Carbonized block manufacturing method for producing isostatic graphite

1 shows a method for manufacturing a carbonized block for producing isotropic graphite according to an embodiment of the present invention.

A carbonized block manufacturing method for producing isotropic graphite according to an embodiment of the present invention includes mixing coke and binder pitch; kneading the mixture at a final kneading temperature of 250° C. or higher; shaping the kneaded product; and carbonizing the molded body.

In the kneading step, kneading may be performed at a final kneading temperature of 250° C. or higher. Specifically, the kneading final temperature of the kneading step may be 250 ° C to 300 ° C. In this case, the density of the carbonized block obtained after carbonization can be increased. It is understood that this is because the formation of pores in the carbide due to the generation of volatile gas in the subsequent carbonization step can be reduced by sufficiently removing the volatile components of the binder in the kneading step. In this specification, the kneading final temperature means the highest temperature during the kneading process.

The kneading may be performed at 120°C to 300°C. Specifically, it may be performed at 150 °C to 280 °C. If the kneading temperature is too low, a large amount of low molecular weight volatile matter is present in the kneaded material, and a large amount of gas is generated in the heat treatment process after kneading. Accordingly, the density or mechanical strength of the block may be reduced, and if the kneading temperature is too high, the binder pitch may be solidified and the formability of the block may be deteriorated in the molding process.

The kneading may be performed for 50 minutes to 300 minutes. Specifically, it may be performed for 80 minutes to 150 minutes.

When the kneading time satisfies the above range, the coke and the binder pitch are sufficiently mixed, the binder pitch can be uniformly formed on the surface of the coke particles, and the volatile content of the kneaded material can be controlled to an appropriate level.

The coke may have a D50 of 20 μm or less. Specifically, it may be 4 μm to 20 μm, 10 μm to 20 μm, or 15 μm to 20 μm.

If the particle size of the coke is too large, the moldability of the block may be deteriorated in the molding process, and if the particle size is too small, a problem in that the amount of pitch required due to the increase in the specific surface area of the particles may occur.

The coke may be isotropic coke or anisotropic coke. Specifically, petroleum-based coke, coal-based coke, earthy graphite, pulverized acicular coke, and/or carbides obtained from other biomass and the like can be applied.

In the mixing step, the binder pitch may be 30 wt% or more based on 100 wt% of the mixture. Specifically, the binder pitch content may be 30 wt% to 40 wt%. If the binder pitch content is too small, the density of the carbonized block may be lowered, and if the binder pitch content is too large, it is difficult to express uniform physical properties of the molded body, the carbonization yield is lowered, and the porosity is excessively increased. .

When the binder pitch content is 30 wt% or more and the final kneading temperature is 250 ° C. or more, the binder pitch penetrates well into the pores of the coke, and accordingly, the density of the carbonized block can be improved.

In the mixing step, the binder pitch may have a heat treatment yield of 50 wt% or more at 500 ° C. Specifically, the binder pitch may have a heat treatment yield of 50 wt% to 70 wt% at 500 °C. When the above range is satisfied, since a high carbonization yield is obtained during thermal decomposition, the density of the carbonized block can be further improved.

In the kneading step, the volatile matter content of the kneaded product may be 10 wt% or less. Specifically, the volatile matter content of the kneaded product may be 1 to 10 wt%, 3 to 10 wt%, or 5 to 8.5 wt%. When the above range is satisfied, it is possible to solve the problem of lowering the density of the block due to the generation of volatile gas in the carbonization step, and to manufacture a high-density carbonized block.

The carbide obtained in the carbonization step may have an apparent density of 1.3 g/cc or more. Specifically, the lower limit of the apparent density may be 1.3 g/cc or more, 1.38 g/cc or more, 1.4 g/cc or more, or 1.5 g/cc or more, and the upper limit may be 1.8 g/cc or less, 1.7 g/cc or less, or 1.6 g/cc or less. cc or less. More specifically, it may be 1.3 to 1.8 g/cc, 1.38 to 1.7 g/cc, 1.4 to 1.7 g/cc, 1.5 to 1.7 g/cc, or 1.5 to 1.6 g/cc. That is, the carbonized block obtained by the manufacturing method of the present invention may be a high-density carbonized block with improved density.

The carbide obtained in the carbonization step may have a porosity of 32% or less. Specifically, the upper limit of the porosity may be 30% or less, 26% or less, 25% or less, or 21% or less, and the lower limit may be 19% or more, or 20% or more. More specifically, the porosity may be 19 to 32%, 20 to 26%, or 20 to 23%.

The binder pitch may have a QI content of 2 wt% or more. Specifically, the lower limit of the QI content may be 2 wt% or more, 2.5 wt% or more, 4 wt% or more, or 4.5 wt% or more, and the upper limit may be 10 wt% or less, 7 wt% or less, or 7 wt% or less, 5 wt% may be below. More specifically, it may be 2 to 10 wt%, 4 to 7 wt%, or 4 to 6 wt%. If the QI content of the binder pitch is too large, a problem may occur in the uniformity of the internal structure, and if the QI content is too small, a problem of a rapid decrease in yield during carbonization may occur.

The binder pitch may have a beta-resin content of 20 wt% or more. Specifically, the lower limit of the beta-resin content may be 20 wt% or more and 23 wt% or more, and the upper limit may be 28 wt% or less, 26 wt% or less, 25 wt% or less, 24 wt% or less, or 23 wt% or less. may be less than wt %. In cases where the content of beta-resin is as high as possible, the adhesive force between coke particles is increased, which is advantageous for characteristics such as yield, and in the case where it is small, the opposite may occur.

The molding may be to prepare a molded article by pressurizing the kneaded material in the range of 100 to 280 MPa. Specifically, it may be 100 to 200 MPa. If the molding pressure is too large, a molded article may be damaged, and if it is too small, the density may be lowered and a damage problem may occur due to stress concentration during heat treatment.

The molding may be performed at room temperature, and specifically, may be performed by a method such as cold isostatic pressure molding (CIP), vibration molding, and the like.

Prior to the forming step, crushing and screening the kneaded material; may further include. This is to remove pulverized and agglomerated particles before molding to ensure uniformity when put into the molding mold.

The step of grinding and screening may be to control the particle size of the kneaded material to 5 μm or less. Specifically, it may be controlled to 3 μm or less or 1 μm or less. In this case, it is possible to ensure sufficient uniformity and secure the density of the molded product when inputting the molding mold.

The screening may be performed by removing particles larger than the mesh size through a screen in consideration of the desired particle size, and in the following examples, the screening is performed using a 1 μm mesh.

In the mixing step, coke may have a span value of 1.3 or less. Specifically, it may be greater than 0 and less than or equal to 1.3, or 0.1 to 1.3.

The span value means [(d90-d10)/d50] value, and when the above range is satisfied, the contact area between the particle specific surface area and the input pitch is constant, which is advantageous in terms of quality control.

The carbonizing step may be performed at 800 °C to 1400 °C.

In the carbonizing step, the temperature increase rate may be 1 to 5 °C/min.

In the carbonization step, decomposition gas of organic matter is generated, expansion due to heat in the initial stage of heating, and volume contraction due to polycondensation reaction occur thereafter. In addition, when the size of the molded body increases, it becomes difficult to generate gas, and the possibility of cracking due to the temperature difference between the surface and the inside of the molded body increases. When the above range is satisfied, the molded article can be fired while suppressing crack generation.

The isotropic graphite manufacturing method of the present invention may further include, after the carbonizing step, graphitizing the carbide.

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The carbonized block for producing isotropic graphite manufactured according to an embodiment of the present invention has an improved density, and when it is graphitized, isotropic graphite having a higher density can be produced.

In addition, the isotropic graphite manufacturing method according to the embodiment of the present invention may further include additional processes in addition to the presented processes, if necessary.

Preferred examples and comparative examples of the present invention are described below. However, the following example is only a preferred embodiment of the present invention, but the present invention is not limited to the following example.

Raw material

Isotropic coke (PMP grade) manufactured by PMC Tech was used for coke.

As for the binder pitch, Rutgers' Bx95KS (binder pitch A) and OCI's U2 pitch (binder pitch B) were used.

binder pitch Volatile content (wt%) QI content
(wt%) Beta-resin content (wt%) Binder Pitch A
(Bx95KS) 51.9 2.7 23.6 Binder Pitch B
(U2) 46.5 4.9 20.5

carbonized block manufacturing

280 kg of pitch coke was input and controlled into two particle sizes of 10 and 20 μm based on d50 through coarse grinding, fine grinding, and air flow classification, and the span was controlled to 1.3 or less to reduce process deviation for each batch. At this time, the recovery rate against the total input amount was 83.5%. The classified coke powder was put into a kneading machine (Kurimoto, container volume 2L, Japan) with binder pitch of 25, 30, and 35 wt%, respectively, pre-mixing was performed at room temperature for 30 minutes, and then target temperature Kneading was performed while raising the temperature to . The heating rate is 3℃/min, and the target temperature is maintained for 100 minutes, and then cooled to room temperature after natural air cooling. The cooled kneaded material was fitted with a 1 μm mesh using a jaw crusher, and re-ground and classified.

CIP molding was performed using the uniformly controlled powder that had been completed up to the re-grinding/classification. In the molding process, a molder made of silicone rubber with an inner diameter (Ф) of 60 mm and a height (H) of 65 mm was used, and the amount of powder input was 120 to 160 g, and the mold was maintained at a pressure of 100 MPa and 200 MPa for 10 minutes, respectively. The obtained molded article was heated up to 1,000 °C in a carbonization furnace (Noritake, equipped with volatile matter combustion equipment, Japan) at a rate of 5 °C/min and maintained for 1 hour. It was carried out in a nitrogen atmosphere to prevent oxidation, and the area around the sample was filled with coke powder to prevent oxidation. After that, the power was turned off and allowed to cool naturally to room temperature.

Table 2 shows the specific experimental conditions and volatile content of the kneaded products of Experimental Examples 1 to 16.

Binder pitch type Coke granularity
(D50, μm) Kneading final temperature (℃) and holding time (min) pitch input
(wt%) plastic surgery
enter
(MPa) kneaded product
Volatile content
(wt%) Experimental Example 1 Binder Pitch A 10 150℃(100min) 25 100 11.7 Experimental Example 2 30 14.2 Experimental Example 3 35 15.1 Experimental Example 4 25 200 11.7 Experimental Example 5 30 14.2 Experimental Example 6 35 15.1 Experimental Example 7 250℃(100min) 25 100 5.1 Experimental Example 8 30 6.0 Experimental Example 9 35 7.5 Experimental Example 10 25 200 5.1 Experimental Example 11 30 6.0 Experimental Example 12 35 7.5 Experimental Example 13 Binder Pitch B 10 250℃(100min) 35 100 8.1 Experimental Example 14 200 8.1 Experimental Example 15 20 100 6.5 Experimental Example 16 200 6.5

Characterization of carbonized blocks

The apparent density of the carbonized graphite block was measured based on the Archimedes method.

Table 3 shows the specific experimental conditions of Experimental Examples 1 to 16 and the apparent density and porosity before and after carbonization.

Binder pitch type Coke granularity
(D50, μm) Kneading final temperature and holding time pitch input
(wt%) plastic surgery
enter
(MPa) before carbonization After carbonization H
(mm) Φ
(mm) V
(cm ³ ) ρ
(g/cm ³ ) H
(mm) Φ
(mm) V
(cm ³ ) ρ
(g/cm ³ ) Apparent density
(g/cc) porosity
(volume%) Experimental Example 1 Binder Pitch A 10 150℃
(100min) 25 100 50.9 49.8 99.2 1.31 50.5 49.7 97.7 1.21 1.21 35.6 Experimental Example 2 30 50.9 49.5 98.1 1.35 50.3 48.8 94.1 1.26 1.29 30.5 Experimental Example 3 35 50.6 48.3 92.6 1.4 49.3 47 85.3 1.33 1.33 27.1 Experimental Example 4 25 200 50.3 48.9 94.5 1.37 50.7 49.1 96 1.23 1.25 32.3 Experimental Example 5 30 51.1 48.8 95.5 1.47 50.7 49.9 98.9 1.27 1.31 25.6 Experimental Example 6 35 48.6 47.9 87.7 1.48 48.4 47.2 84.6 1.34 1.37 23.5 Experimental Example 7 250℃
(100min) 25 100 52.4 51.9 111 - 52.1 51.5 108 - 1.22 36.6 Experimental Example 8 30 51.9 51.1 106 - 51.6 50.2 102 - 1.32 31.6 Experimental Example 9 35 51 48.4 93.8 - 48.9 46.7 83.5 - 1.43 26.3 Experimental Example 10 25 200 52.5 50.8 107 - 52.3 50.8 106 - 1.27 33.3 Experimental Example 11 30 50.7 50.3 101 - 50.2 49.9 98 - 1.36 29 Experimental Example 12 35 50.2 47.7 89.6 - 48.8 46.1 81.4 - 1.46 24.7 Experimental Example 13 Binder Pitch B 10 250℃
(100min) 35 100 50.8 48.9 95.2 1.33 48.5 46.8 83.6 1.39 1.44 25.5 Experimental Example 14 200 49.7 47.5 88 1.44 48.2 46.4 81.4 1.43 1.45 25.2 Experimental Example 15 20 100 51.2 50.1 101 1.37 48.5 47.8 86.8 1.46 1.5 21.2 Experimental Example 16 200 50.8 49.3 96.9 1.43 48.1 47.3 84.3 1.52 1.52 20.3

It can be seen that when the final kneading temperature is 250°C, the density of the carbonized block is improved compared to the case where the final kneading temperature is 150°C.

In addition, it can be seen that when the binder pitch content is 30 wt% or more, the carbonization density is increased compared to the case where the binder pitch content is 25 wt%.

That is, when the binder pitch content is 30 wt% or more and the final kneading temperature is 250 ° C. or more, it is understood that the pitch penetrates well into the pores of the coke, and the density of the carbonized block is improved.

In addition, when kneading was performed at a final kneading temperature of 150 ° C, the density tended to decrease after carbonization rather than before carbonization, but in the case of a kneaded product at a final kneading temperature of 250 ° C, the density tended to increase after carbonization. This is believed to be caused by the fact that the volatile components of the binder pitch are not sufficiently removed in the kneading process and develop a porous structure in the process of being discharged to the outside as a gas during the carbonization process.

Figure 2 shows the change in carbonization density according to the pitch content for each kneading final temperature. When the kneading final temperature is 250 ° C., it can be seen that the density increases more rapidly with the increase in pitch content. That is, it can be seen that when the pitch content is 30 wt% or more, the inventive example having a kneading final temperature of 250 ° C. has a higher carbonization density than the comparative example even if the molding pressure is low.

3 shows the porosity change according to the pitch content for each kneading final temperature. It can be seen that the porosity decreases as the pitch content increases. That is, it can be seen that the increase in pitch content affects the improvement of carbonization density according to the decrease in porosity.

When binder pitch B is used under the same conditions, the carbonization density tends to increase more than when binder pitch A is used.

In addition, when binder pitch B is used, the density tends to increase after carbonization compared to before carbonization under the conditions of a kneading final temperature of 250 ° C.

This is due to the physical properties of the binder pitch itself, and it is understood that the chemical structure of the binder pitch B (U2 pitch) has a high carbonization yield during thermal decomposition because it contains many components with high molecular weight.

4 is a result of analyzing the thermal decomposition behavior of binder pitch A (Bx95KS) and binder pitch B (U2 pitch) by TGA. It can be seen that the binder pitch B has a high yield of about 2 wt% or more at 900 ° C. during kneading under the same conditions.

Under the same conditions, when large powder having a particle size d50 of 20 μm was applied, it was confirmed that the carbonization density increased from 1.45 g/cc to 1.52 g/cc compared to the case where the d50 was 10 μm.

Through these results, it can be seen that the pitch type, content, and raw material coke particle size affect the improvement of density, which is one of the important physical properties of the carbonized block for producing isotropic graphite.

Characteristic evaluation of isotropic graphite

Graphitization was performed at 3000 ° C. using an induction heating furnace for the carbonized block prepared under the conditions of Table 4 below, and the density was measured after graphitization.

Referring to Table 4, it can be seen that when graphitization is performed under the same conditions, a graphite block having a high density can be manufactured by using a carbonized block having a high density. That is, it can be seen that the density of the carbonized block affects the density after graphitization.

However, this experiment is only to confirm the effect of the density of the carbonized block on the density after graphitization, and the density after graphitization depends on the applied graphitization method, graphitization process conditions, impregnation process and re-carbonization process, etc. It may vary, and the present invention is not limited to the following experimental examples.

Binder pitch type Coke granularity
(D50, μm) Kneading final temperature (℃) and holding time (min) pitch input
(wt%) plastic surgery
enter
(MPa) Apparent density after carbonization
(g/cc) Density after graphitization
(g/cc) Isostatic Graphite Experimental Example 1 Binder Pitch B
(U2) 10 250
(100min) 35 200 1.52 1.69 Isostatic Graphite Experimental Example 2 Binder Pitch A
(Bx95KS) 10 250
(100min) 35 200 1.46 1.58

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those skilled in the art to which the present invention pertains may take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (12)

Mixing coke having a D50 of 20 μm or less and a binder pitch;
kneading the mixture at a final kneading temperature of 250° C. or higher;
shaping the kneaded product; and
Including; carbonizing the molded body;
In the mixing step, the binder pitch is 30 wt% or more based on 100 wt% of the mixture,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 1,
In the mixing step, the binder pitch has a heat treatment yield of 50 wt% or more at 500 ° C.
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 2,
In the kneading step, the volatile content of the kneaded material is 10 wt% or less,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 2,
The carbide obtained in the carbonization step has an apparent density of 1.4 or more,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 2,
The carbide obtained in the carbonization step has a porosity of 25.5% or less,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 2,
The binder pitch has a QI content of 4 wt% or more and a beta-resin content of 20 wt% or more,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 1,
The binder pitch has a QI content of 2 wt% or more and a beta-resin content of 20 wt% or more,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 1,
The molding step is to prepare a molding by pressurizing the kneaded material in the range of 100 MPa to 280 MPa,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 1,
In the mixing step, the coke has a span value of 1.3 or less,
Carbonized block manufacturing method for producing isotropic graphite.
According to claim 1,
After the kneading step,
Further comprising crushing and screening the kneaded material,
Carbonized block manufacturing method for producing isotropic graphite.
Graphitizing the carbonized block prepared by the method of claim 1; comprising
Isotropic graphite manufacturing method.
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