KR102653132B1 - Recycled Graphite extrusion-molded bodies and manufacturing method therefor - Google Patents

Abstract

The present invention can produce bulk graphite in large quantities by reusing graphite waste generated in the graphite manufacturing process, thereby significantly improving productivity and economic efficiency, and at the same time, producing anisotropic bulk graphite with uniform physical properties. Provides a recycled graphite extruded body and a method for manufacturing the same, which greatly improves its usability.

Description

Recycled graphite extrusion-molded bodies and manufacturing method therefor}

The present invention relates to recycled graphite extrusions and methods for manufacturing the same.

Carbon is a chemically stable element that plays an important role in the mechanical and chemical industries. Physically, it has both metallic and ceramic properties, and has van der Waals bonds in the c-axis direction, and a and b planes perpendicular to it. Since there are covalent bonds in the phase, it has the characteristic of showing great anisotropy. In particular, it is considered to be a material with excellent lubricity, heat resistance, thermal shock resistance, thermal conductivity, and corrosion resistance, which are not found in metals or ceramics.

Graphite, one of the materials that can be used as such a carbon material, has characteristics that are superior to other materials in heat resistance, corrosion resistance, electrical conductivity, high-temperature strength, and lubricity. Therefore, graphite is attracting attention in various fields such as high-temperature structural materials such as electrodes, carbon brushes, and mechanical seals, and special mechanical parts.

However, the conventional technology of molding graphite and using it as a carbon material has the following problems, which limits its use.

First, the uniaxial pressure molding process has been introduced as a method for manufacturing conventional graphite molded bodies. When the molded body is manufactured according to this, the particles that make up the graphite are arranged in a disorderly manner, showing isotropy. As a result, the structure becomes dense and the strength increases, thereby improving the electrical properties. , In particular, the resistivity shows a very high value. Accordingly, in industries that require smooth flow of current or low specific resistance within the graphite molded body, for example, in the electrode manufacturing field, graphite molded bodies manufactured using the pressure molding process cannot be used, and the properties of graphite cannot be fully utilized. There are problems with its use in various fields.

Second, when manufacturing a graphite molded body using the above-described conventional method, a stress gradient occurs within the molded body, making it difficult to obtain a graphite molded body with uniform density, and problems such as distortion, deformation, and cracks occur due to such density unevenness. There is. In addition, in order to solve the problems of such non-uniform graphite molded bodies and obtain uniform graphite molded bodies, graphite must be molded and processed under high temperature and high pressure conditions, which reduces productivity and economic efficiency.

Third, most of the graphite is dependent on overseas imports, and the imported graphite is not fully utilized in the processing process, generating about 30% of graphite waste in the form of scrap or powder. These graphite waste scraps are added to increase the carbon content in molten iron at steel mills or are recycled by being used to manufacture graphite-added refractories. However, only a small amount of graphite scrap is recycled and most of them are discarded, resulting in serious economic problems. , it is causing environmental problems.

Accordingly, by recycling the graphite waste scraps generated in the artificial graphite manufacturing process, it is eco-friendly and economical can be greatly improved. At the same time, bulk graphite, which has anisotropy and can significantly lower the resistivity, can be manufactured, increasing the scope of use. There is an urgent need to develop recycled graphite molded bodies that can significantly improve .

Republic of Korea Publication No. 2012-0112676 (2012.10.11)

The present invention was devised to overcome the above-mentioned problems. The problem to be solved by the present invention is to significantly improve productivity and economic efficiency by recycling graphite waste scraps generated in the graphite manufacturing process, and at the same time, to have anisotropy. Accordingly, the aim is to provide a recycled graphite extruded body and a manufacturing method thereof that can produce bulk graphite that can significantly lower the specific resistance, thereby greatly improving its usability.

In order to solve the above-described problems, the present invention provides the following steps: (1) mixing graphite waste scrap powder with a binder and additives to produce a graphite mixture; (2) extruding the graphite mixture to produce an extruded body; (3) A method for producing a recycled graphite extruded body is provided, comprising the steps of drying and carbonizing the extruded body and (4) filling pores in the carbonized extruded body.

Additionally, according to one embodiment of the present invention, the graphite waste scrap powder in step (1) may be a by-product generated in the artificial graphite manufacturing process.

Additionally, the graphite waste scrap powder may have an average particle size of 20 to 200 ㎛.

Additionally, the binder may be any one or more selected from phenol resin, pitch, polyester resin, urea resin, melamine resin, silicone resin, furan resin, and epoxy resin.

Additionally, the graphite waste scrap powder and binder may be mixed at a weight ratio of 1:0.1 to 0.3.

Additionally, the binder and additives may be mixed at a weight ratio of 1:0.1 to 5.0.

Additionally, extrusion molding may be performed at 80 to 160 MPa.

In addition, step (5) of recarbonizing the extruded body after step (4) may be further included.

Additionally, steps (4) and (5) may be repeated one to three times.

Additionally, step (4) may be performed with an impregnation solution in which binder and additives are mixed at a weight ratio of 1:0.5 to 2.

It may also be characterized by satisfying Equation 1 below.

[Equation 1]

1.01 ≤ ≤ 1.07

The present invention provides a recycled graphite extrusion body comprising graphite waste scrap powder and having a resistivity of 20 to 40 μΩm.

Additionally, the average particle size of the graphite waste scrap may be 20 to 200 ㎛.

Additionally, the recycled graphite extruded body may have a density of 1.3 g/cm³ or more as measured by Measurement Method 1 below.

[Measurement method 1]

Cut the recycled bulk graphite into 10mm x 10mm x 10mm, measure specific gravity using ASTM D792 method, and then convert the density.

According to the recycled graphite extruded body and its manufacturing method according to the present invention, productivity and economic efficiency can be significantly improved by recycling graphite waste scraps generated in the graphite manufacturing process, and at the same time, the specific resistance can be significantly lowered due to its anisotropy. Since bulk graphite can be manufactured in large quantities, its utilization can be greatly improved.

1 is a flowchart of a method for manufacturing a recycled graphite extrusion molding according to the present invention.
Figure 2 is a photograph of graphite waste scrap powder separated according to particle size according to an embodiment of the present invention.
Figure 3 is a photograph showing an extruded graphite molded body according to an embodiment of the present invention.
Figure 4 is a photograph of an extruder used in the extrusion process according to an embodiment of the present invention.
Figure 5 is a photograph showing an impregnation solution according to an embodiment of the present invention.
Figure 6 is a photograph showing dividing the extruded graphite molded body into specimens to evaluate the electrical properties of the extruded graphite molded body according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in many different forms and is not limited to the embodiments described herein.

As described above, according to the conventional graphite molded body and its manufacturing method, it is not possible to produce an anisotropic graphite molded body, so there is a limit to its utilization, and there are problems such as the inevitable discarding of waste scrap and the inability to manufacture a uniform graphite molded body, etc. , there were significant difficulties in applying it to various industrial fields.

Accordingly, the present invention provides the following steps: (1) mixing graphite waste scrap powder with a binder and additives to produce a graphite mixture (S10); (2) extruding the graphite mixture to produce an extruded body (S20); (3) A solution to the above-mentioned problem was sought by providing a method for manufacturing a graphite extruded body including the steps of drying and carbonizing the extruded body (S30) and (4) impregnating the carbonized extruded body to fill the pores (S40). .

Through this, productivity and economic efficiency can be significantly improved by recycling graphite waste scraps generated in the graphite manufacturing process. At the same time, bulk graphite, which has anisotropy and can greatly reduce resistivity, can be manufactured, greatly improving its usability. You can.

Hereinafter, the method for manufacturing a graphite extruded body according to the present invention will be described in detail with reference to FIGS. 1 to 6.

The present invention includes step (1) (S10) of mixing graphite waste scrap powder with a binder and additives to produce a graphite mixture.

Typically, graphite used in various industries relies on imports, but more than 30% of imported graphite is treated or discarded as waste graphite scrap or powder waste during the graphite processing process, resulting in a huge waste of foreign currency and an increase in costs for related companies. It is acting as a factor. Accordingly, processing companies are defined as polluting industries and the dust and waste generated during the processing process are regulated. However, small-scale businesses do not have any practical regulations or guidance measures, so they dispose of graphite waste scraps as general waste, resulting in continuous environmental pollution. However, there are no realistic alternatives for how to overcome these problems.

Accordingly, the present invention can produce bulk graphite by recycling graphite waste scraps generated in the above-described graphite processing process and to be disposed of as waste. That is, in step (1), the graphite waste scrap powder according to the present invention may be a by-product generated in the above-described graphite processing process or artificial graphite manufacturing process. In this case, the waste graphite scrap powder, which is the main material in the bulk graphite manufacturing process, is recovered and reprocessed into filler for use, thereby greatly improving environmental and process economics.

At this time, the recycled graphite waste scrap powder can be used by classifying the particle size to have appropriate mechanical/electrical properties depending on the purpose of the final extruded graphite molded body. In other words, the particle size of the graphite waste scrap powder affects the mechanical/electrical properties including density, electrical conductivity, or tensile strength of the extruded graphite molded body to be finally manufactured, so as shown in FIG. 2, the graphite in step (1) The waste scrap powder may be used with an average particle size of 20 to 200 ㎛, more preferably 30 to 150 ㎛, and most preferably 40 to 80 ㎛.

More specifically, referring to Figure 3, among the extruded graphite molded bodies finally manufactured by varying the average particle size of the graphite waste scrap powder in step (1) to 50 ㎛, 100 ㎛, 5 mm, and 10 mm, respectively, those within the numerical range of the present invention It can be seen that when graphite waste scrap with an average particle size of 50 ㎛ (FIG. 3(a)) and 100 ㎛ (FIG. 3(b)) was manufactured into powder, an intact extruded body was manufactured. In particular, in the case of the extruded body manufactured at 50 ㎛, it can be seen that the most intact extruded body was produced with almost no minor cracks.

In other words, if the average particle size of the graphite waste scrap powder in step (1) is less than 20㎛, a molded body is formed, but cracks may occur during drying due to the small particle size. Also, if in step (1) the graphite waste scrap powder If the average particle size exceeds 200㎛, many pores may be generated based on the formed cracks, making it impossible to completely perform the extrusion molding process, or a bursting phenomenon may occur centered on the cracks, making it impossible to manufacture an extruded body.

Next, in step (1), the binder serves to bind the graphite waste scrap powder described above.

Accordingly, the binder can be a conventional binder that can bind graphite waste scrap powder, and non-limiting examples include phenol resin, pitch, polyester resin, urea resin, melamine resin, silicone resin, furan resin, and epoxy. It may be any one or more selected from resins, etc., and preferably at least one selected from the group consisting of novolak-based, resol-based, alkylphenol-based and rosin-modified phenol resins can be used, more preferably novolac-based or A resol type can be used.

This binder can be mixed at a weight ratio of 1:0.1 to 0.3 based on the graphite waste scrap powder so that the graphite waste scrap powder can be granulated and bonded. At this time, if the weight ratio of the graphite waste scrap powder and the binder is less than 1:0.1, there may be a problem in that the graphite waste scrap powder is not sufficiently granulated and does not bind, and if the weight ratio of the graphite waste scrap powder and the binder is 1: If it exceeds 0.3, there is a risk that excessive pores are created in the graphite molded body during the carbonization process described later, thereby reducing the density and durability of the final extruded graphite molded body produced.

Next, in the above step (1), the additive plays the role of improving the bonding strength between the above-described graphite waste scrap powder and the binder and acts as a solvent. Any organic solvent commonly used in the art is suitable for the purpose of the present invention. It can be used without limitation, preferably at least one selected from the group consisting of ethanol, methanol, acetone, formaldehyde and hexamethylenetetramine, more preferably at least one selected from the group consisting of ethanol and methanol. can be used.

Such additives can be mixed at a weight ratio of 1:0.1 to 5.0, preferably 1:0.1 to 2, based on the total weight of the binder. At this time, if the additive is mixed at a ratio of less than 1:0.1 based on the binder, the durability of the final graphite extruded body may be reduced due to insufficient bonding power, and if the additive is mixed at a ratio of less than 1:5 based on the binder, the durability of the final graphite extruded body may be reduced. When mixed, there may be a problem that mechanical properties such as bending strength of the final manufactured graphite extruded body are deteriorated.

Meanwhile, the above-described graphite waste scrap, binder, and additives can be mixed using a known mixer that can be used as a mixer for mixing them without limitation. For example, the mixer may be a pot mill, ball mill, or rotary mixer, but is limited thereto. It doesn't work.

Next, the present invention includes step (2) (S20) of producing an extruded body by extruding the graphite mixture.

Generally, in order to manufacture a molded body by processing graphite, a pressure molding process is performed. According to the pressure molding process, the particles that make up graphite are arranged in a disorderly manner, showing isotropy, and as a result, the structure becomes dense and the strength increases, improving the electrical properties, especially The resistivity shows a very high value. Accordingly, in industries that require smooth flow of current or low specific resistance within the graphite molded body, such as electrode manufacturing, graphite molded bodies manufactured using a pressure molding process cannot be used, so their utilization is limited.

Accordingly, the present invention can also produce bulk graphite with anisotropy that the conventional pressure molding process could not produce by using the extrusion molding process. More specifically, referring to Table 3 below, the graphite molding agent (Examples 1 to 4) manufactured by the extrusion molding process according to the present invention is graphite manufactured under the same conditions as Examples 1 to 4 through the conventional pressure molding process. It can be seen that the specific resistance is reduced by more than 200% compared to the molded body (Comparative Example 1).

In other words, in order to manufacture a graphite molded body with anisotropy through a conventional pressure molding process, an additional high-temperature and high-pressure heat treatment process must be performed. However, according to the extrusion molding process according to the present invention, graphite with anisotropy of a plate-like structure can be produced under much milder conditions. Since molded bodies can be manufactured, it can be utilized in industrial fields that require low specific resistance, and at the same time, economic feasibility can be greatly improved by shortening the production process. In addition, mass production is possible at a much lower cost than the conventional pressure molding process, and productivity is also significantly improved, ensuring utilization in a wider range of industries.

To this end, the extrusion molding in step (2) can be performed at 0.8 to 5.0 M/min and 80 to 160 MPa, and more preferably at 100 to 140 MPa. That is, while in the conventional pressure molding process, the graphite mixture is molded under high pressure conditions of 2000 bar (200 MPa) to 4000 bar (400 Mpa), according to the extrusion molding process according to the present invention, the molding process is performed at a much lower pressure, thereby improving the stability and stability of the production process. Economic feasibility can be improved. At this time, if the extrusion molding pressure in step (2) is less than 80 MPa, the molded body may not maintain its shape and may be extruded in powder form, and if the extrusion molding pressure in step (2) exceeds 160 MPa, the speed is fast. Due to the shape of the molded body, the molded body may not be straight but may be curved or curved. Meanwhile, the extrusion molding process in step (2) can be performed using a conventional extrusion molding machine as long as it is suitable for the purpose of the present invention. As a non-limiting example, the extrusion molding process is performed using an extruder mold as shown in Figure 3. can do.

Next, the present invention includes step (3) (S30) of drying and carbonizing the extruded body prepared in step (2).

The drying process may use a conventional drying process in the art that can sufficiently dry the manufactured extruded body. A non-limiting example of this may be drying in an oven at a temperature of 50°C to 150°C for 24 to 72 hours. .

The carbonization process is a step of heat treating the extruded body manufactured in step (2) in an inert atmosphere. Through the carbonization process, graphite crystals develop, and at the same time, a significant amount of the binder is volatilized and removed, thereby causing a polycondensation reaction. Particulate graphite powder is fixed in a certain shape.

To this end, the carbonization process in step (3) may be performed by raising the temperature to 500°C to 900°C at a rate of 0.5°C/min to 5°C/min and then heat treating for 0.3 to 2 hours, more preferably The temperature can be raised to 600℃/min to 700℃/min. At this time, if the carbonization process in step (3) is performed at a temperature below 500 ℃, there may be a problem that carbonization may not be sufficiently achieved, and if it is performed at a temperature exceeding 900 ℃, the extruded graphite molded body may thermally expand and be damaged. Problems such as cracks may occur. Meanwhile, while the conventional pressure molding process involves carbonization and heat treatment at a temperature of 700°C to 1500°C, the extrusion molding process according to the present invention can perform step (3) at a lower temperature, which can be much more advantageous in terms of process energy economy.

At this time, in the carbonization process of step (3), volatile components such as binders are removed and pores are formed in the graphite extruded body. The formed pores reduce the airtightness of the graphite extruded body, lowering mechanical strengths such as tensile strength and density. It causes it to happen.

Accordingly, the present invention includes step (4) (S40) of impregnating the carbonized extruded body with an impregnating liquid to fill the pores.

In step (4), the mechanical strength and oxidation stability of the graphite extruded body can be increased by impregnating the pores with an impregnation solution mixed with a binder and additives. At this time, the binder and additives used in step (1) described above may be used, but are not limited thereto, and conventional binders and additives in the art that meet the purpose of the present invention may be used.

At this time, the impregnation liquid may be mixed with the binder and additives at a weight ratio of 1:0.5 to 2, more preferably, the binder and additives may be mixed at a weight ratio of 1:0.7 to 1.6, and most preferably, the binder and Additives can be mixed at a weight ratio of 1:0.9 to 1.2.

More specifically, referring to FIG. 5 below, in the case of FIG. 5(a) where the binder and additive are mixed at a ratio of 1:0.4, it can be seen that the binder does not sufficiently dissolve in the additive and clumps due to the high viscosity of the mixed solution. In addition, in the case of FIG. 5(b) where the binder and additive are mixed at a ratio of 1:1, it can be seen that the binder is uniformly dissolved in the additive. In addition, in the case of FIG. 5(c) where the binder and additive were mixed at a ratio of 1:2.3, the binder was sufficiently dissolved due to the high specific gravity of the additive, but the impregnation effect is expected to be reduced due to the high specific gravity of the additive during drying and recarbonization.

That is, in the impregnation solution, when the binder and additive are mixed at a weight ratio of less than 1:0.5, the binder is not sufficiently dissolved in the additive and partially clumps, and the mechanical strength and density of the graphite extruded body are reduced due to failure to impregnate the inside of the pores. There may be. Additionally, if the impregnation solution contains a binder and additive mixed in a ratio exceeding 1:2, there may be a problem in that the impregnation effect on pores is reduced due to the high specific gravity of the additive during drying and recarbonization.

Next, the present invention may further include a step (5) of recarbonizing the extruded body after step (4).

The recarbonization step is a step of further improving the mechanical strength and density of the graphite extrusion molded body by recarbonizing the graphite extruded body impregnated with the impregnating liquid in step (4), and is performed at the same temperature as the carbonization step in step (3) described above. It can be done.

Meanwhile, steps (4) and (5) may be repeated one to three times. That is, the step (5) is to fill the pores by impregnating the graphite extruded body carbonized in step (4) with an impregnation liquid and recarbonizing it to manufacture a graphite extruded body with better density. ) If the step is repeated one or more times, a graphite extruded body with higher density can be manufactured.

Additionally, the graphite extruded body according to the present invention can satisfy Equation 1 below.

[Equation 1]

1.01 ≤ ≤ 1.07

Referring to Table 2 below, the density can be improved by about 1% to about 7% depending on the impregnation of the graphite extruded body according to the present invention. As described above, impregnation can be repeated 1 to 3 times, and as the number of impregnations increases, the density increase rate may decrease.

Additionally, the graphite extruded body according to the present invention can satisfy Equation 2 below.

[Equation 2]

1.04 ≤ ≤ 1.07

Referring to Table 2 below, the density can be improved by about 4% to about 7% depending on one-time impregnation of the graphite extruded body according to the present invention.

In this way, according to the method of manufacturing a recycled graphite molded body according to the present invention, productivity and economic efficiency can be significantly improved by recycling graphite waste scraps generated in the graphite manufacturing process, and at the same time, the specific resistance can be significantly lowered due to its anisotropy. Since bulk graphite can be manufactured, its utilization can be greatly improved.

Next, the recycled graphite molded body according to the present invention will be described. However, in order to avoid duplication, descriptions of parts that have the same technical idea as those described in the manufacturing method of recycled graphite molded bodies will be omitted.

The present invention provides a recycled graphite extrusion body comprising graphite waste scrap powder and having a resistivity of 20 to 40 μΩm.

Generally, in order to manufacture a molded body by processing graphite, a pressure molding process is performed. However, according to the pressure molding process, the particles that make up graphite are arranged in a disorderly manner and become isotropic, thereby making the structure denser and increasing the strength. At this time, the isotropic graphite molded body exhibits very high electrical properties, especially resistivity. Accordingly, the smooth flow of current within the graphite molded body is required, so it can be used in industries that require low resistivity, such as electrode manufacturing. There is a problem that it is difficult to utilize it in various fields.

Accordingly, the present invention can also manufacture bulk graphite with anisotropy that the conventional pressure molding process could not produce using the extrusion molding process, and can exhibit a resistivity reduced by more than 200% compared to bulk graphite manufactured by the conventional uniaxial pressure molding process. there is.

Additionally, recycled graphite waste scrap powder can be used by classifying the particle size to have appropriate mechanical/electrical properties depending on the purpose of the final extruded graphite molded body. That is, the particle size of the graphite waste scrap powder affects the mechanical/electrical properties including density, electrical conductivity, or tensile strength of the extruded graphite molded body to be finally manufactured, so the average particle size of the graphite waste scrap may be 20 to 200 ㎛, More preferably, graphite waste scrap powder of 30 to 150㎛, most preferably 40 to 80㎛, can be used.

Meanwhile, the graphite extruded body according to the present invention may have a density of 1.3 g/cm³ or more as measured by Measurement Method 1 below.

[Measurement method 1]

Cut the recycled bulk graphite into 10mm x 10mm x 10mm, measure specific gravity using ASTM D792 method, and then convert the density.

Referring to Table 2 below, it can be seen that all graphite extruded bodies according to the present invention have a density of 1.3 g/cm³ or more. In other words, the graphite extrusion molded body using recycled graphite waste scrap according to the present invention exhibits an excellent density that can be used in actual industries and has a density close to that of the graphite molded body made from graphite rather than waste scrap, making it a graphite that can be simply discarded. Beyond recycling waste scrap, economics and productivity can be greatly improved. On the other hand, if the density is less than 1.3 g/cm³, the pores created during the carbonization process may not be sufficiently impregnated or sufficiently bonded by the binder, resulting in problems with mechanical strength.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples do not limit the scope of the present invention, and should be interpreted to aid understanding of the present invention.

Example 1 - Preparation of graphite extrusions

(One) Step: Preparing the graphite mixture

Purchase the EDM-3 product from POCO Graphite in the U.S. as graphite waste strap powder, prepare 10,000 g of processed by-product powder discarded after processing artificial graphite, and use CB-8081 phenol resin from Gangnam Hwaseong as a binder at 25% weight of graphite waste scrap. After mixing at a ratio of %, ethanol was mixed as an additive at a ratio of 25% of the weight of the binder.

(2) step: Steps for manufacturing an extruded body

The extrusion process was performed at a speed of 120 MPa at 1.2 M/min using the extrusion equipment shown in Figure 3 below, and after extruding 1000 mm, it was cut at 500 mm intervals.

(3) step: Drying and carbonization steps

The extruded body prepared in step (2) was dried at 80°C for 48 hours using an oven. Afterwards, it was placed in the center of the quartz boat and then charged into the hot zone of a horizontal tubular furnace (300 mm from the center) and carbonized at 700°C. The temperature increase rate was adjusted to 2°C/min, and an inert atmosphere was created with nitrogen gas inside the tubular furnace to prevent oxidation of the molded body during carbonization. The inflow rate of nitrogen gas into the tubular furnace was set to 1 liter/min.

(4) Step: Impregnation Step

In step (3), CB-8081 phenol resin and ethanol, sufficient to sufficiently submerge the carbonized graphite extrusion, were mixed in a ratio of 5:5 and stirred for 30 minutes using a mixer, and then the graphite extrusion was added to Carbo Co., Ltd. Impregnation was performed using a reduced pressure method using an impregnation machine available in the lab. Afterwards, it was dried at room temperature for 30 minutes and then recarbonized at a temperature of 1000 degrees.

Examples 2 to 4 - Preparation of graphite extrusions

It was prepared in the same manner as in Example 1, except that the average particle size of the graphite waste scrap powder and the ratio of the binder and additives in the impregnation solution were varied as shown in Table 1 below.

Comparative Examples 1, 2, 4 to 6 - Preparation of graphite extruded body

It was prepared in the same manner as in Example 1, except that the average particle size of the graphite waste scrap powder, the ratio of binder and additives in the impregnation solution, and the extrusion pressure were varied as shown in Table 1 below.

Comparative Example 3 - Manufacture of graphite molded body by pressure molding

It was manufactured in the same manner as Example 1, except that (2) a pressure molding process was performed instead of an extrusion process.

Specifically, graphite waste scrap as in Example 1 and CB-8081 phenol resin from Gangnam Hwaseong were mixed at a weight ratio of 8:2, ethanol was mixed as an additive at a ratio of 25% of the weight of the phenol resin, and the mixture was molded at 240 MPa using a 60x60x50mm mold. Pressure molding was performed.

Graphite waste scrap powder
average particle size Proportion of binders and additives in impregnation liquid extrusion pressure
(MPa) Example 1 50㎛ 1:1 120 Example 2 100㎛ 1:1 120 Example 3 25㎛ 1:1 120 Example 4 150㎛ 1:1 120 Comparative Example 1 50㎛ 1:0.4 120 Comparative Example 2 50㎛ 1:2.3 120 Comparative Example 3 Pressure molding Comparative Example 4 5mm 1:1 120 Comparative Example 5 10 mm 1:1 120 Comparative Example 6 50㎛ 1:1 120

Experimental Example 1 - Determination of moldability of graphite extruded body

The formability of the graphite extruded bodies manufactured in Examples 1 and 2 and Comparative Examples 4 and 5 was judged by visual inspection and internal pore size, and these are shown in Figures 3A to 3D, respectively.

Referring to FIGS. 3A to 3D, when graphite waste scraps having an average particle size of 50 ㎛ (FIG. 3(a)) and 100 ㎛ (FIG. 3(b)), which are within the numerical range of the present invention, are manufactured into powder, the intact It can be seen that the extrusion molded body was manufactured. In particular, in the case of the extruded body manufactured at 50 ㎛, it can be seen that the most intact extruded body was produced with almost no minor cracks. However, if it is outside the numerical range according to the present invention, it can be seen that cracks occur or are damaged.

Experimental Example 2 - Evaluation of the prepared impregnation solution

The impregnating solutions prepared in Example 1 and Comparative Examples 1 and 2 were stirred for 30 minutes and are shown in Figures 5A to 5C.

Referring to FIGS. 5A to 5C, in the case of FIG. 5(a) where the binder and additive are mixed at a ratio of 1:0.4, it can be seen that the binder is not sufficiently dissolved in the additive and lumps are formed due to the high viscosity of the mixed solution. In addition, in the case of Figure 5(b), where the binder and additive are mixed at a ratio of 1:1, it can be seen that the binder is uniformly dissolved in the additive. In addition, in the case of Figure 5(c), where the binder and additive were mixed at a ratio of 1:2.3, the binder was sufficiently dissolved due to the high specific gravity of the additive, but the impregnation effect is expected to be reduced due to the high specific gravity of the additive during drying and recarbonization.

Experimental Example 3 - Graphite extruded body density measurement

The graphite extruded bodies prepared in Examples 1 to 4 were cut into 10x10x10mm as shown in Figure 5, and the density was measured using an Archimedes equipment, and the results are shown in Table 2 below.

Before impregnation Width (cm) Height (cm) Height (cm) Weight (g) Density (g/cm ³ ) Example 1 10.81 11.04 10.84 1.6129 1.25 Example 2 11.05 10.85 11.42 1.7259 1.26 Example 3 11.34 11.07 11.12 1.7683 1.27 Example 4 11.05 10.04 11.05 1.5551 1.27 1 time impregnation Width (cm) Height (cm) Height (cm) Weight (g) Density (g/cm ³ ) Example 1 10.9 11.1 10.9 1.7258 1.31 Example 2 11.1 10.85 11.45 1.8346 1.33 Example 3 11.36 11.11 11.19 1.8963 1.34 Example 4 11.1 10.04 11.06 1.6679 1.35 Impregnation twice Width (cm) Height (cm) Height (cm) Weight (g) Density (g/cm ³ ) Example 1 10.92 11.2 10.94 1.8224 1.36 Example 2 11.11 10.86 11.47 1.9356 1.4 Example 3 11.36 11.17 11.23 1.9718 1.38 Example 4 11.12 10.05 11.05 1.7531 1.42 3 times impregnation Width (cm) Height (cm) Height (cm) Weight (g) Density (g/cm ³ ) Example 1 10.94 11.2 10.97 1.8688 1.39 Example 2 11.15 10.87 11.5 1.9861 1.42 Example 3 11.37 11.17 11.27 2.019 1.41 Example 4 11.2 10.15 11.04 1.8243 1.45

Experimental Example 4 - Measurement of resistivity of graphite extruded body

The electrical properties of the graphite molded bodies prepared in Examples 1 to 4 and Comparative Example 3 were measured and shown in Table 3 below.

width
(mm) thickness
(mm) width
(cm) thickness
(cm) cross-sectional area
( ^Cm2 ) between
(cm) electric current
(A) Voltage
(mV) Voltage
(V) resistivity
(μΩm) Example 1 10.67 9.56 1.067 0.956 1.02 1.60 0.5 2.5 0.0025 31.87663 Example 2 10.67 9.56 1.067 0.956 1.02 1.60 1.0 4.9 0.0049 31.23909 Example 3 10.67 9.56 1.067 0.956 1.02 1.60 1.5 7.3 0.0073 31.02658 Example 4 10.67 9.56 1.067 0.956 1.02 1.60 2.0 9.8 0.0098 31.23909 Comparative Example 3 10.41 10.95 1.041 1.095 1.14 1.60 0.5 4.8 0.0048 68.3937

Referring to Table 3, the graphite molding agent (Examples 1 to 4) manufactured by the extrusion molding process according to the present invention is the graphite molding agent (Examples 1 to 4) manufactured under the same conditions as Examples 1 to 4 through the conventional uniaxial pressure molding process. It can be seen that the resistivity is reduced by more than 200% compared to Comparative Example 3). In other words, in order to manufacture a graphite molded body with anisotropy through a conventional pressure molding process, an additional high-temperature and high-pressure heat treatment process must be performed. However, according to the extrusion molding process according to the present invention, graphite with anisotropy of a plate-like structure can be produced under much milder conditions. Since molded bodies can be manufactured, it can be utilized in industrial fields that require low specific resistance, and at the same time, economic feasibility can be greatly improved by shortening the production process. In addition, mass production is possible at a much lower cost than the conventional pressure molding process, and productivity is also significantly improved, ensuring utilization in a wider range of industries.

Claims (14)

(1) mixing graphite waste scrap powder with a binder and additives to prepare a graphite mixture;
(2) manufacturing an extruded body by extruding the graphite mixture;
(3) drying and carbonizing the extruded body; and
(4) filling the pores of the carbonized extruded body; Including,
After step (4) above,
(5) A method for producing a recycled graphite extruded body, further comprising recarbonizing the extruded body.
According to paragraph 1,
A method of manufacturing a recycled graphite extruded body, characterized in that the graphite waste scrap powder is a by-product generated in the artificial graphite manufacturing process.
According to paragraph 1,
A method of producing a recycled graphite extruded body, characterized in that the graphite waste scrap powder has an average particle size of 20 to 200 ㎛.
According to paragraph 1,
The binder is a method of producing a recycled graphite extruded body, characterized in that it contains at least one selected from phenol resin, pitch, polyester resin, urea resin, melamine resin, silicone resin, furan resin, and epoxy resin.
According to paragraph 1,
A method for producing a recycled graphite extruded body, characterized in that the graphite waste scrap powder and the binder are mixed at a weight ratio of 1:0.1 to 0.3.
According to paragraph 1,
A method for producing a recycled graphite extruded body, characterized in that the binder and additives are mixed at a weight ratio of 1:0.1 to 5.0.
According to paragraph 1,
Step (2) is a method of producing a recycled graphite extruded body, characterized in that extrusion molding is performed at a pressure of 80 to 160 MPa.
delete According to paragraph 1,
A method for producing a recycled graphite extruded body, characterized in that step (4) and step (5) are repeated one to three times.
According to paragraph 1,
Step (4) is a method of producing a recycled graphite extruded body, characterized in that it is performed with an impregnation solution in which binder and additives are mixed at a weight ratio of 1:0.5 to 2.
According to clause 9,
A method of manufacturing a recycled graphite extruded body, characterized in that it satisfies the following equation 1.
[Equation 1]
1.01 ≤ ≤ 1.07
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