KR101612529B1 - Pressurized crucible for preparing graphite - Google Patents

Abstract

The present invention relates to a pressurizing crucible which can be used to prepare graphite by applying vertical pressure, a furnace comprising the crucible to prepare graphite, and a preparation method of graphite using the crucible. The crucible of the present invention can effectively pressurize raw materials and can be used to prepare graphite from raw materials with high efficiency. Further, the crucible of the present invention can be used for shrinking or carbonization and/or to graphitization through heat treatment by inductive heating, and thus can substantially reduce graphitization temperature by improving heating efficiency in comparison to a conventional method while reducing processing costs. In addition, the crucible enables the furnace to rapidly operate, precisely control temperature, and can be used to design various furnaces while having excellent barrier properties from contaminant substances and being environment-friendly. The pressurizing crucible comprises: (a) a crucible body which has a screw thread at the entire or in part of an internal flank of an opening, wherein the screw thread combines with a crucible cap; and (b) a crucible cap which includes a screw thread formed at the exterior, wherein the screw thread combines with the internal flank of the opening of the crucible body.

Description

[0001] PRESSURIZED CRUCIBLE FOR PREPARING GRAPHITE FOR GRAPHITE MANUFACTURING [0002]

The present invention relates to a crucible for pressurization for producing graphite, and more particularly, to a crucible for pressurization which can effectively produce graphite by applying a vertical pressure, a calcination furnace for producing graphite containing the crucible, and a crucible ≪ / RTI >

Graphite is important as an industrial material because it has excellent heat resistance, chemical resistance, high thermal conductivity and high electric conductivity. It is also widely used as a radiating element such as a heat radiating material, a heat resistant sealing material, a gasket, a heating element and an X-ray monochrometer, a fuel cell separator, . In addition to the use of graphite alone, it is widely used as a heat-dissipating material, an electronic device case, and an aircraft material by forming a composite with a resin.

As a representative example of the method for producing an artificial film-like graphite, there is a method called " expanded graphite method ". In this method, artificial graphite is prepared by immersing natural graphite in a mixed solution of concentrated sulfuric acid and concentrated nitric acid, and then rapidly heating the natural graphite. This artificial graphite is processed into a film shape by a high-pressure press, a roll or the like after the acid is removed by washing. However, the film-shaped graphite produced in this way has weak strength, does not have excellent physical characteristics, and has a problem that influence of residual acid is worried.

In order to solve such a problem, a method of graphitizing a polymer film as a raw material by direct heat treatment has been developed (hereinafter referred to as " polymeric graphitizing method "). Examples of the polymer film used for this purpose include polyoxadiazole, polyimide, polyphenylene vinylene, polybenzoimidazole, polybenzoxazole, polythiazole, polyamide film and the like . The polymeric graphitizing method is characterized by a method which does not substantially involve the incorporation of impurities such as acid in a much simpler method as compared with the conventional expanded graphite method and also has excellent thermal conductivity and electrical conductivity close to that of single crystal graphite ( Japanese Unexamined Patent Publication (Kokai) No. 60-181129, Japanese Unexamined Patent Application, First Publication No. Hei 7-109171, Japanese Unexamined Patent Application, First Publication No. Sho 61-275116).

However, in the case of such a high-molecular-weight graphitization method, a long time heat treatment at a very high temperature is required for graphitization. Generally, for conversion to graphite of good quality, a heat treatment for 30 minutes or more is required in a temperature range of 2900 占 폚 or more.

However, a crucible capable of effectively pressurizing the raw material has not yet been known. Japanese Laid-Open Patent Publication No. 2002-14467 discloses a crucible for graphitization processing, and Korean Laid-Open Publication No. 2008-62310 discloses a crucible for manufacturing an electroluminescent display device.

Japanese Patent Application Laid-Open No. 60-181129 Japanese Unexamined Patent Publication No. 7-109171 Japanese Patent Application Laid-Open No. 61-275116 Korean Published Unexamined Patent Application No. 2002-14467 Korean Published Patent No. 2008-62310

An object of the present invention is to provide a crucible capable of effectively producing graphite by pressurizing a raw material.

Another object of the present invention is to provide a calcining furnace for producing graphite including the crucible.

It is still another object of the present invention to provide a method for producing graphite using the crucible.

According to one aspect, the present invention provides a process for producing a crucible comprising: (a) a threaded upper open crucible body screwable to a crucible cap on all or a portion of the inner side of the opening; And (b) a screw-formed crucible cap screwed to the outside of the opening of the crucible body so as to be screwed into the crucible body. The raw material is charged into the crucible body and the crucible cap is rotated to pressurize the raw material A crucible for pressurization for producing graphite is provided.

According to another aspect, the present invention provides a honeycomb structure comprising: (a) a threaded upper open crucible body screwable with a crucible cap on a portion of the outer side of the opening; And (b) a crucible cap having a threaded support portion screwable with an outer side surface of the opening portion of the crucible body and a body portion screwed with the support portion, wherein the raw material is charged into the crucible body, A crucible for pressurization for producing graphite is provided which is capable of pressing a raw material by locking the body portion and locking it.

According to yet another aspect, the present invention relates to a crucible as described above; And a heat insulating material surrounding all or a part of the outside of the crucible.

According to another aspect, the present invention provides a method of manufacturing a crucible, comprising: (a) charging a raw material into the crucible described above; And (b) graphitizing the raw material by heat treatment, wherein the heat treatment in step (b) induction-heats the raw material at the same time as the induction heating of the crucible, Of the present invention.

Since the crucible of the present invention can effectively pressurize the raw material, it can be used to produce the graphite with high efficiency from the raw material. In addition, since the crucible of the present invention can be used to perform shrinkage, carbonization and / or graphitization through heat treatment by induction heating, the heating efficiency is improved as compared with the conventional method, and the graphitization temperature can be drastically lowered, Can be greatly reduced. In addition, it is possible to design with rapid operation, precise temperature control and various firing furnace, excellent barrier property from pollutants and environment friendly.

The above and other objects and features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
1 is a perspective view of a pressurizing crucible for producing graphite according to a first embodiment of the present invention.
2 is a vertical cross-sectional view of a pressurizing crucible for producing graphite according to a first embodiment of the present invention.
3 is a perspective view of a pressurizing crucible for producing graphite according to a second embodiment of the present invention.
4 is a vertical cross-sectional view of a pressurizing crucible for producing graphite according to a second embodiment of the present invention.
5 is a perspective view of a pressurizing crucible for producing graphite according to a third embodiment of the present invention.
6 is a vertical sectional view of a pressurizing crucible for producing graphite according to a third embodiment of the present invention.
7 is a cross-sectional view of a calcining furnace for producing graphite according to an example of the present invention.

The crucible for pressurization according to the present invention crucible )

According to an aspect of the present invention, there is provided a honeycomb structure comprising: (a) a threaded upper open crucible body capable of being screwed with a crucible cap on all or a part of an inner side surface of an opening; And (b) a screw-formed crucible cap screwed to the outside of the opening of the crucible body so as to be screwed into the crucible body. The raw material is charged into the crucible body and the crucible cap is rotated to pressurize the raw material A pressurizing crucible for producing graphite is provided.

Preferred embodiments of the crucible will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a pressurizing crucible for producing graphite according to a first embodiment, and Fig. 2 is a vertical sectional view of Fig.

As shown in the figure, the crucible 100 of the present invention comprises a crucible body 200 and a crucible cap 300.

The crucible body 200 has a cylindrical shape having an opening at an upper portion thereof and a thread 400 is formed at an inner side surface of the opening portion.

The crucible lid 300 is coupled to the opening of the crucible body 200 and has a thread 500 formed on the outer side of the crucible 300 so as to be threadedly formed on the inner side surface of the opening of the crucible body 200 400). The crucible lid 300 is formed in a circular cross section according to the shape of the crucible body 200.

When the raw material is charged into the crucible body 200, the crucible 100 for pressurizing the crucible 100 can press the raw material by locking the crucible cap 300. The threads 400 formed on the crucible body may be formed on a part of the inner side surface of the opening. Alternatively, in order to maximize the pressing effect, the threads 400 formed in the crucible body may be formed on the entire inner side surface of the opening. Accordingly, the crucible lid 300 can be moved deeply from the opening to the bottom of the crucible, thereby maximizing the pressurization.

3 is a perspective view of a pressurizing crucible for producing graphite according to a second embodiment, and Fig. 4 is a vertical sectional view of Fig.

As shown in the drawing, the crucible for pressurization according to the second embodiment is characterized in that the inner bottom of the crucible body 200 and the lower end of the crucible lid 300 are curved as a whole, as compared with the crucible of the first embodiment . In this figure, the inner bottom of the crucible body 200 and the lower end of the crucible cap 300 are all curved convex shapes. However, those skilled in the art will recognize that only one of them has a convex curved shape You can do it. The crucible for pressurization 100 according to the second embodiment is formed in such a manner that one or both of the inner bottom of the crucible body 200 and the lower end of the crucible cap 300 are formed in a generally convex curved shape, Having a convex curved surface shape having a radius of curvature of 1000 cm to 1000 cm, there is an advantage that a uniform pressure can be applied vertically. The crucible body may have a hole penetrating the side surface or passing through the crucible cap.

According to another aspect of the present invention, there is provided a honeycomb structure comprising: (a) a threaded upper open crucible body screwable with a crucible cap on a portion of an outer side of an opening; And (b) a crucible cap having a threaded support portion screwable with an outer side surface of the opening portion of the crucible body, and a body portion screwed with the support portion, wherein the raw material is charged into the crucible body, There is provided a pressurizing crucible for producing graphite, which can pressurize the raw material by locking the body part by locking.

Preferred embodiments of the crucible will be described in detail with reference to the accompanying drawings.

FIG. 5 is a perspective view of a pressurizing crucible for producing graphite according to a third embodiment, and FIG. 6 is a vertical sectional view of FIG.

As shown in the drawing, the pressing crucible 100 for producing graphite according to the third embodiment comprises a crucible body 200 and a crucible cap 300.

The crucible body 200 has a cylindrical shape having an opening at an upper portion thereof, and a thread 400 is formed at an outer portion of the opening.

The crucible cap 300 includes a threaded support 310 threadedly engaged with an outer side surface of the opening of the crucible 200 and a body 320 screwed to the support. The supporting part 310 of the crucible cap is coupled to the opening of the crucible body 200 and the thread formed on the supporting part 310 is screwed and fixed to the thread 400 formed on the outer side surface of the opening part of the crucible body, The thread formed in the body portion 320 of the crucible cap is combined with another thread formed in the support portion 310. [ The crucible lid 300 is formed in a circular cross section according to the shape of the crucible body 200.

When the raw material is loaded into the crucible body 200, the pressing crucible 100 can press the raw material by locking the body portion 320 of the crucible cap.

The crucible 100 of the present invention described above is preferably made of a material containing graphite, more preferably made of graphite.

Although only the cylindrical shape of the crucible is mentioned above, those skilled in the art will recognize that box, flat, and tunnel shapes may also be used.

The crucible 100 may have a wall thickness of 1 mm to 200 mm, specifically 5 mm to 30 mm, more specifically 10 mm to 20 mm.

For more efficient induction heating, the thickness of the wall surface of the crucible 100 can be appropriately controlled in consideration of the penetration depth of the electromagnetic wave.

The crucible 100 may include at least one hole formed in its wall or lid.

Electromagnetic waves can penetrate into the raw material through the holes, so that efficient induction heating can be performed, and out gas generated during the shrinkage or carbonization process and the graphitization process can be easily discharged. However, if the holes are too large or too large, heat in the crucible 100 flows out to the outside, so that it is necessary to appropriately control the size of the holes.

Graphite  Firing furnace for production

The present invention relates to the aforementioned crucible; And a heat insulating material surrounding all or a part of the outside of the crucible.

The calcining furnace is for producing graphite by heat-treating a raw material for forming graphite.

The firing furnace may further include an induction heating coil located outside the heat insulating material.

The raw material for forming the graphite may be a mixture of organic and inorganic sources and may be in the form of a sheet or a film, or in the form of agglomerated powder or powder.

Hereinafter, a firing furnace for producing graphite according to an example of the present invention will be described in detail.

The following specific examples of the calcining furnace for producing graphite are intended to illustrate the present invention, but the present invention is not limited to the following examples.

7 is a cross-sectional view of a calcining furnace for producing graphite according to an example of the present invention.

7, the firing furnace 600 for producing graphite includes a crucible 100 to which a raw material 700 for forming graphite is charged, a heat insulating material 630 to cover all or part of the outside of the crucible 100; And an induction heating coil 610 located outside the heat insulating material 630.

Specifically, an induction heating coil 610 may be disposed outside the heat insulating material 630 to surround the heat insulating material 630, or may be disposed on at least one surface of the heat insulating material 630.

In addition, the firing furnace 600 for producing graphite may further include a current generator for flowing an alternating current to the induction heating coil 610. The frequency of the alternating current flowing from the current generator to the induction heating coil 610 is as described above.

When a current is supplied to the induction heating coil 610, a magnetic field is formed around the induction heating coil 610 and the electromagnetic induction causes the eddy current loss And heat due to hysteresis loss is generated, and heat treatment by induction heating is performed.

The induction heating coil 610 may be an external type coil disposed outside the crucible 100 or the heat insulating material 630 or may be an internal type coil inserted into the interior thereof or a mixed type coil .

For example, the induction heating coil 610 may be configured to surround and surround the heat insulating material 630 from the outside of the heat insulating material 630. As another example, the induction heating coil 110 may be disposed on at least one surface of the exterior of the heat insulating material 630. As another example, the induction heating coil 610 may be configured to be inserted into the heat insulator 630. Further, a coil configuration in which the above-described configurations are mixed is also possible.

The induction heating coil 610 may have a circular, elliptical or quadrangular cross-sectional shape, or a cross-sectional shape in which these shapes are mixed.

In addition, the induction heating coil 610 may have various winding types such as a multi-winding type or a single-winding type.

As an example, the induction heating coil 610 may be a multi-winding coil, and may have a circular, elliptical or quadrangular winding shape. In this case, the induction heating coil 610 may be configured to surround and surround the outside of the heat insulating material 630.

As another example, the induction heating coil 610 may have a flat pancake coil form as a multi-turn coil, and may be disposed on at least one surface of the exterior of the heat insulating material 630 in this case.

As another example, the induction heating coil 610 may have a helical winding shape as a multiple winding coil, and may be arranged to surround a part of the heat insulating material 630 from the outside of the heat insulating material 630 in this case.

As another example, the induction heating coil 610 may be a multi-turn coil and may have a circular winding shape with a narrow winding diameter, and may be configured to be inserted inside the insulation 630 in this case.

In addition, a coil shape in which the above-described shapes are mixed is also possible.

The induction heating coil 610 may be wound in a circular shape, an elliptical shape, or a quadrangle shape as a single coil type coil. In this case, the induction heating coil 610 may be configured to surround and surround the outside of the heat insulating material 630, As shown in FIG.

Therefore, the arrangement, the shape, and the like of the induction heating coil 610 provided in the baking furnace 600 for producing graphite can be appropriately configured in accordance with the intended induction heating conditions.

As the current flows through the induction heating coil 610, a current flows in the crucible 100 due to electromagnetic induction, and current flows also in the raw material 700.

Accordingly, only the crucible 100 may be heated by induction heating, and the crucible 100 and the raw material 700 may be heated simultaneously or sequentially. Preferably, the crucible 640 and the raw material 700 can be heated simultaneously by induction heating.

Further, the raw material 700 may be subjected to indirect heating by heating the crucible 100 at a low temperature, and indirect heating and direct heating (direct heating) at a high temperature. At this time, since the crucible 100 and the heat insulating material 630 may be oxidized (etched) due to oxygen or the like during the heating, argon or nitrogen gas may be injected into the furnace for purging or non- Atmosphere to protect the crucible 100 and the heat insulating material 630 and prevent external contamination.

The heat insulating material 630 may be made of a material including ceramic, porous graphite, and the like.

In addition, the crucible 100 and the heat insulating material 630 may be disposed in the reactor 120 having a single or double wall surface of a quartz material. Accordingly, the induction heating coil 610 may be disposed outside the reactor 620.

In addition, the crucible 100 may further include a container for containing the raw material 700 disposed therein. Accordingly, the raw material 700 may be charged into the crucible 100 while being contained in the container.

Graphite  Manufacturing method

The present invention provides a method for producing graphite using the crucible described above.

The method for producing graphite according to the embodiment can provide the graphite in the form of powder or sheet. The method of producing the graphite powder may be such that the compression step is omitted after the graphite sheet is produced, or the graphite sheet is pulverized after the graphite sheet is manufactured. The raw material can be produced by a method such as heat treatment in a powder state without passing through a sheet or a film, and a person skilled in the art can easily estimate the method. Therefore, unless otherwise specified, Explain it.

(A) charging the raw material into the crucible of any one of claims 1 to 6; And b) graphitizing the raw material by heat treatment, wherein the heat treatment in step (b) may include induction heating of the raw material simultaneously or sequentially with induction heating of the crucible have.

In another embodiment of the present invention, the method for producing graphite comprises the steps of: (a) providing a raw material; (b) a shrinkage or carbonization step; And (c) a graphitization step, which can be produced by performing heat treatment by induction heating in the shrinkage or carbonization step and / or the graphitization step.

Hereinafter, a method for producing graphite according to an example of the present invention will be described in detail for each step.

(a) Providing raw materials

(i) an organic source

The raw material includes an organic source for forming graphite.

The organic source may be a raw material that can be converted to graphite by heat treatment. The organic source may comprise a polymeric resin. More specifically, the organic source may comprise an aromatic polymer. More specifically, the organic source may be composed of the polymer resin.

The polymer resin may be at least one selected from the group consisting of polyimide, polyamide, polyacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyethylene, polyethylene naphthalate, polyoxadiazole, polybenzothiazole, polybenzobisthiazole, A group composed of benzoxazole, polybenzobisoxazole, polypyrromellitic imide, aromatic polyamide, polyphenylene benzoimitazo r, polyphenylene benzobisimitazo r, polythiazole and polyparaphenylene vinylene , And may be a homopolymer or a copolymer.

The organic source may be provided in the form of particles. That is, the organic source may be in powder form. More specifically, the organic source may include plate-like, polyhedral, or spherical organic particles.

The particle size of the organic particles (polymer resin particles) contained in the organic source is not limited. For example, it may have a size of from a few hundred nanometers to a few tens of millimeters, but the embodiment is not limited thereto.

For example, the average particle diameter (D50, based on primary particles) of the polymer resin particles may be about 0.1 占 퐉 to about 1,000 占 퐉, about 0.1 占 퐉 to about 500 占 퐉, and about 0.1 占 퐉 to about 200 占 퐉. More specifically, the average particle size of the organic particles may be from about 1 [mu] m to about 100 [mu] m.

Alternatively, the organic source may be provided in the form of a liquid prepolymer. The prepolymer may be chemically reacted with a cross-linking agent, a catalyst, or the like, and consequently may be formed into a sheet or film shape.

Alternatively, the organic source may be provided in a molten state. That is, the organic source may be melted by heat and formed in a chip form. The chip-type organic source can be extruded into a sheet form through an extruder or the like.

( ii ) Weapon Sources

The raw material may further include an inorganic source for forming graphite.

The inorganic source is a raw material for forming the graphite sheet according to the embodiment. The inorganic source may be an inorganic material containing carbon. The inorganic source may be an inorganic material that can be converted to graphite by heat treatment. The inorganic source may include graphite or an inorganic material having a graphite structure. More specifically, the inorganic source may comprise graphite, such as artificial graphite, impression graphite or expandable graphite. In another embodiment, the inorganic source may include carbon nanotubes having a graphite structure, carbon nanofibers, and the like. The expandable graphite may be graphite which is treated by an intercalant, such as sulfuric acid, and which can be expanded by heat. The expandable graphite can be expanded by a factor of several times to several thousand times by the applied heat.

The inorganic source may be provided in the form of particles. That is, the inorganic source may be in powder form. More specifically, the inorganic source may include plate-like, polyhedral, or spherical inorganic particles.

The average particle size of the inorganic particles contained in the inorganic source is not limited. For example, the average particle size (D50) of the inorganic particles may range from about 0.1 占 퐉 to about 1,000 占 퐉, more specifically from about 0.1 占 퐉 to about 500 占 퐉, more specifically from about 0.1 占 퐉 to about 300 占 퐉, To about 300 [mu] m. More specifically, the average particle size of the inorganic particles may be about 1 탆 to about 200 탆.

( iii ) Organic / inorganic hybrid

As an example, the raw material may be a mixture of organic and inorganic sources.

In the case where the raw material is an organic-inorganic compound, step (a) of providing the raw material may include the steps of (a-1) providing an inorganic source for forming the graphite; (a-2) providing an organic source comprising a polymeric resin; And (a-3) mixing the inorganic source and the organic source to form an organic-inorganic hybrid.

The organic source may be a raw material which is converted into graphite by heat treatment, and may perform a binder function for preventing the inorganic source from falling off.

The content of the inorganic source in the organic-inorganic hybrid material is about 10 parts by weight or more, more specifically 30 parts by weight or more, more specifically 50 parts by weight or more, and more preferably 100 parts by weight or less, Or more. The content of the inorganic source may be 900 parts by weight or less based on 100 parts by weight of the organic source.

If the content of the inorganic source is too low, more energy may be consumed in the process of heat-treating the mixture, and the cost can not be achieved. When the content of the inorganic source is too high, the mixture can not be easily prepared into a desired shape. Further, when the content of the inorganic source is too high, the thermal conductivity in the horizontal direction can be remarkably reduced.

The organic-inorganic hybrid material may further include a binder, specifically, an organic binder.

For example, the step (a-3) of forming the organic / inorganic mixture may comprise the steps of: preparing a slurry comprising the organic source, the inorganic source, the binder and the solvent as a detailed step; Casting the slurry; And removing the solvent contained in the slurry.

The organic binder may function to mechanically bond the organic source and the inorganic source to each other.

The organic binder may be converted to graphite by heat treatment, and may be removed during a binder removal process, a drying process, and a shrinkage or carbonization process.

Examples of the organic binder include a polyvinyl resin such as polyvinyl alcohol; Polyvinyl acetal based resins such as polyvinyl butyral; Acrylic resin; Polyurethane resin; Rubber-based resins such as ethylene-propylene-diene monomer (EPDM, ethylene-propylene-diene monomer), silicone and butadiene; Or a mixture thereof. More specifically, a polyvinyl butyral resin may be used as the organic binder. The organic binder may be present in an amount of up to about 200 parts by weight, more specifically up to about 10 parts by weight, and more specifically up to about 50 parts by weight, based on 100 parts by weight of the organic source. More specifically, the organic binder may include up to about 30 parts by weight based on 100 parts by weight of the organic source.

When the organic source is supplied in the form of particles, the organic source, the inorganic source, the binder and the solvent may be uniformly mixed to prepare a slurry. The slurry is then cast into a sheet or film form. Thereafter, the solvent may be removed through a drying process, and an organic / inorganic hybrid may be formed.

The drying process may be carried out at a temperature between about 80 [deg.] C and about 200 [deg.] C. The drying process may be conducted for about 30 seconds to about 2 hours.

As the solvent, an alcohol such as ethanol or an organic solvent such as toluene may be used. The solvent may be used in an amount such that the slurry has an appropriate viscosity and can be easily cast. For example, the solvent may comprise from about 20% to about 70% by weight, based on the weight of the slurry.

In addition, the slurry may further contain additives such as a dispersing agent or defoaming agent to improve dispersibility and processability.

When the organic source includes the polymer resin particles, pores may be formed between the polymer resin particles. The organic / inorganic hybrid mixture may include pores. The pores may be formed while the solvent is dried and removed.

Further, when the inorganic source includes inorganic particles, pores may be formed between the polymeric resin particles and the inorganic particles. Also, pores may be formed between the inorganic particles.

The size and the porosity of the pores of the organic-inorganic hybrid material can be variously controlled by the content of the polymeric resin particles, the diameter of the polymeric resin particles, the content of the inorganic particles, and the diameter of the inorganic particles.

The porosity of the organic / inorganic hybrid may be from about 1% by volume to about 30% by volume. More specifically, the porosity of the organic / inorganic hybrid may be from about 2% by volume to about 20% by volume. More specifically, the porosity of the organic / inorganic hybrid may be about 3% by volume to about 10% by volume.

The organic / inorganic base mixture may be produced in the form of a sheet or a film. In this case, it can be formed into a rectangular, circular, elliptical or irregular plate form as well as a roll form.

When the organic source is supplied in the form of a liquid prepolymer, the prepolymer, the inorganic source and the solvent can be uniformly mixed. Thereafter, the prepolymer may be chemically reacted with a crosslinking agent, a catalyst, or the like, and an organic / inorganic hybrid may be formed. The organic / inorganic base mixture may be processed into a sheet or film form. For example, the organic source may be a polyamidic acid solution, and an inorganic source may be mixed with the polyamide acid solution, followed by application to a carrier film, followed by drying to form an organic-inorganic hybrid material. The carrier film may be a metal foil such as an aluminum foil.

Further, after the organic source and the inorganic source are mixed with each other, the organic source is melted by heat, and a chip-like organic / inorganic hybrid material can be formed. The chip-like organic-inorganic hybrid material can be extruded into a sheet-like organic-inorganic hybrid material through an extruder or the like.

When the organic-inorganic hybrid substance is produced in the form of a sheet or a film, the thickness of the organic / inorganic hybrid substance is not limited. For example, the thickness of the organic / inorganic hybrid may be from about 2 탆 to about 1000 탆. More specifically, the thickness of the organic-inorganic hybrid material may be about 5 占 퐉 to about 500 占 퐉. More specifically, the thickness of the organic-inorganic hybrid material may be about 10 탆 to about 200 탆.

The organic-inorganic hybrid material may be produced in the form of a sheet or a film and wound in a cylindrical roll so as to be subjected to subsequent shrinkage, carbonization, or graphitization.

The organic-inorganic hybrid material may have various shapes other than the film or sheet shape. For example, the powder or powder may be in the form of agglomerated agglomerates.

If the raw material is an organic-inorganic mixture containing expandable graphite particles, it may undergo a graphite particle expansion process before or after the subsequent shrinkage or carbonization process, or simultaneously with shrinkage or carbonization process.

Specifically, the organic-inorganic hybrid material is heat-treated at a temperature of about 200 ° C to about 1200 ° C, and the expandable graphite particles in the organic-inorganic hybrid material can be expanded by heat. More specifically, the graphite particle expansion process may be conducted at a temperature of about 500 ° C to about 1100 ° C. More specifically, the graphite particle expansion process may proceed at a temperature of about 750 ° C to about 900 ° C.

The graphite particle expansion process may proceed for about 1 minute to about 30 minutes. By the graphite particle expansion process, the thickness of the organic-inorganic hybrid material can be expanded from about 1.2 times to about 100 times. More specifically, the thickness of the organic / inorganic base mixture can be expanded from about 1.5 times to about 60 times. More specifically, the thickness of the organic / inorganic mixture may be expanded from about 2 times to about 10 times.

In the graphite particle expansion process, physical pressure may be applied to the organic / inorganic hybrid material. For example, the organic-inorganic hybrid material may be sandwiched by two sheets of alumina, graphite, graphite, graphite, or the like, alternately stacked for several to several hundreds, and then subjected to an expansion process.

The graphite particle expansion process may be a separate process or expansion of the expandable graphite particles may be performed in a shrinkage or carbonization process described later. When the shrinkage or carbonization process and the graphitization process are simultaneously performed, the shrinkage or carbonization process or the graphitization process Expansion may occur in the process.

The raw material thus prepared is charged into the crucible and supplied to a shrinking or carbonization process and a graphitization process, which will be described later. Accordingly, the raw material is shrunk or carbonized and then graphitized to form graphite.

(b) shrinkage or carbonization process

The raw material is subjected to a shrinkage or carbonization process by heat treatment.

The shrinkage or carbonization process according to an exemplary embodiment may be performed by heat treating the raw material in an inert gas.

The temperature of the shrinkage or carbonization process may be at least about 400 ° C. More specifically, the temperature of the shrinkage or carbonization process may be at least about 600 ° C. The temperature of the shrinkage or carbonization process may be 400 ° C or higher and lower than 2000 ° C. More specifically, the shrinkage or carbonization process may be performed at a temperature of about 800 ° C to about 1600 ° C, more specifically, at a temperature of about 1000 ° C to about 1400 ° C after the temperature is raised at a rate of about 0.5 ° C / For about 30 minutes to about 4 hours to shrink or carbonize the organic source contained in the raw material. The atmospheric pressure of the shrinkage or carbonization process may be from 700 torr to 760 torr, but is not limited thereto and may proceed under pressure or reduced pressure.

The raw material may be sandwiched by two alumina plates, graphite plates, graphite sheets, graphite films or the like, alternately stacked for several to several hundreds, and then subjected to shrinkage or carbonization.

When the raw material is in the form of a roll, it may be wrapped around a cylindrical core and subjected to the above shrinkage or carbonization process. In this case, the cylindrical core may be a graphite core, and the polymer film and the sheet on which the raw material is laminated may be rolled into a roll shape and then heat-treated. In addition, the raw material may be shrunk or carbonized while unwound from the cylindrical core. The raw material may be unwound from one of the rolls, and the raw material may be shrunk or carbonized in other rolls, Shrinkage or carbonization process may be carried out.

The shrinkage or carbonization process may be performed by induction heating or by resistance heating. The above-mentioned induction heating will be described in detail in the "graphitization step" which will be described later.

Accordingly, the shrinkage or carbonization process may be carried out in an induction heating furnace or in a resistance heating furnace. In addition, it may proceed in the same calcining furnace as the graphitizing furnace described later, or may proceed in different calcining furnaces.

(c) Graphitization  fair

Through the above process, the raw material which has been shrunk or carbonized, for example, the shrunk or carbonized sheet, is heat-treated in an inert gas to be graphitized to form a graphite sheet.

The shrunk or carbonized sheet may be sandwiched by two sheets of graphite, graphite, and graphite, alternately stacked for several to several hundreds, and then subjected to a graphitization process.

Further, when the shrunk or carbonized sheet is rolled, the shrunk or carbonized sheet may be wound around the cylindrical core and then subjected to a graphitization process. The cylindrical core may be made of graphite.

The heat treatment in the graphitization step may be performed at a temperature of 2000 ° C or higher, and specifically, the heat treatment temperature may be at least about 2300 ° C, and more specifically about 2400 ° C or higher.

Also, the heat treatment of the graphitization step may be performed at a temperature of about 3000 ° C or lower. For example, the heat treatment temperature may be about 2800 ° C or less, specifically about 2700 ° C or less, more specifically about 2600 ° C or less, and still more specifically about 2500 ° C or less.

As an example, the heat treatment temperature of the graphitization process can be from about 2000 ° C to about 3000 ° C, specifically from about 2300 ° C to about 2800 ° C, more specifically from about 2400 ° C to about 2700 ° C, And more specifically from about 2400 ° C to about 2600 ° C. The higher the annealing temperature, the higher the degree of graphitization, but the higher the process cost.

The heat treatment of the graphitization process may be performed for about 30 minutes to about 20 hours, more specifically about 30 minutes to about 4 hours. The atmospheric pressure of the graphitization process may be from 700 torr to 760 torr, but is not limited thereto and may proceed under pressure or reduced pressure.

<Induction heating>

According to the present invention, heat treatment in at least one of the above-mentioned "shrinkage or carbonization step" and "graphitization step" is performed by induction heating.

Induction heating is an electromagnetic induction principle in which a current flows through a closed circuit by a temporally varying magnetic field. When a coil is disposed around a heating object such as a conductor to allow an alternating current to flow, an eddy current loss And a hysteresis loss or the like.

For example, the induction heating may be performed by disposing an induction heating coil outside the crucible in which the raw material is charged, and inducing heating of the raw material in the crucible by flowing a current through the induction heating coil.

Accordingly, only the crucible may be heated by the induction heating, and the crucible and the raw material may be heated simultaneously or sequentially.

Here, the simultaneous heating means that, for example, the crucible and the raw material are simultaneously heated by induction.

The sequential heating means that the raw material is heated by the elevated temperature of the crucible as the crucible is inductively heated, for example, and the heated raw material is sequentially heated by induction heating. As a specific example, the crucible is heated by induction heating to generate heat, and the raw material charged into the crucible is heated (indirectly heated) to partially carbonize or graphitize. The carbonized or graphitized raw material can be subjected to induction heating (direct heating) to enhance the heating efficiency.

Preferably, the crucible and the raw material can be heated simultaneously by induction heating.

The induction heating may be performed at a frequency of about 50 Hz to 400 KHz, and specifically may be performed at a frequency of about 500 Hz to 100 KHz, more specifically a frequency of about 1 kHz to 50 kHz, more specifically a frequency of about 3 kHz to 20 kHz .

In the case of induction heating, the current penetration depth varies depending on the frequency, and the change in the current penetration depth of graphite according to the induction heating frequency is shown in Table 1 below.

material Temperature Penetration depth per induction heating frequency 50Hz 500Hz 1 kHz 3 kHz 10 kHz 400 kHz black smoke Room temperature 200 mm 72 mm 50.6 mm 29.3 mm 16 mm 2.5 mm

Therefore, for more efficient induction heating, the wall thickness of the crucible can be appropriately controlled in consideration of the penetration depth of the electromagnetic wave. Specifically, the wall thickness of the crucible may be 0.1 to 5 times the delta defined by the following formula (1), specifically 0.2 to 3 times, more specifically 0.5 to 2 times, more specifically 0.5 to 1.5 times.

&Quot; (1) &quot;

Where _r is the resistivity (Ω · m) of the crucible, f is the frequency (Hz) of the induction heating current, μ _R is the relative permeability of the crucible, μ ₀ is the vacuum permeability (4π × 10 ^-7 H / m).

When the wall thickness of the crucible is within the above preferable range, the induction heating for the raw material can be performed more efficiently and easily.

After the graphitization process by induction heating is completed, a post-finishing process, for example, a softening process, a rolling process, and the like can be further performed.

Example  One: In the first embodiment  Using a crucible Graphite  Manufacture of sheet

A 75 μm thick polyimide film (IFLN or INLV type, SKC KOLON PI) was placed in a graphite crucible (see FIGS. 1 and 2) according to the first embodiment having a wall thickness of 15 mm and charged into an induction heating firing furnace , Screw the lid of the crucible and lock it.

Then, the inside of the calcination furnace was heated to 1100 ° C at a rate of 5 ° C / min under a pressure of 740 torr in an Ar atmosphere, and then carbonized by keeping it for 2 hours.

Thereafter, the carbonized sheet was heated to 2600 ° C at 20 ° C / min under a pressure of 740 torr in an Ar atmosphere, and then maintained at that temperature for 6 hours to carry out the graphitization process.

At this time, the induction heating frequency used in the carbonization process and the graphitization process was 10 kHz.

Thereafter, a graphite sheet having a thickness of 30 mu m was obtained through rolling.

Example  2: In the second embodiment  Using a crucible Graphite  Manufacture of sheet

Except that the graphite crucible according to the second embodiment (convex shape having a radius of curvature of 500 cm from the center of the inside diameter of the curved surface) is used in place of the graphite crucible according to the first embodiment in Embodiment 1 The procedure of Example 1 was repeated to obtain a graphite sheet.

Example  3: In the third embodiment  Using a crucible Graphite  Manufacture of sheet

The procedure of Example 1 was repeated except that the graphite crucible according to the third embodiment (see Figs. 5 and 6) was used instead of the graphite crucible according to the first embodiment in Example 1 to obtain a graphite sheet.

Experimental Example  One: Example  1 Graphite  Measurement of physical properties of sheet

The physical properties (thickness, density, specific heat, thermal diffusivity, and thermal conductivity) of the sheet produced by varying the pressure strength in Example 1 were measured according to a conventionally known method and are shown in Table 2 below.

Item 0.6Mpa 1Mpa 2Mpa 4Mpa 8Mpa Thickness [mm] 0.033 0.032 0.031 0.032 0.033 Density [g / cm3] 1.84 1.99 1.98 2.01 1.94 Specific heat: 50 ℃ [J / g · K] 1.33 1.22 1.28 1.55 1.62 Thermal diffusivity
[Mm 2 / s] Face direction 354.184 409.841 407.475 569.768 569.768 Thickness direction 0.218 0.297 0.198 0.237 0.237 Thermal conductivity
[W / mK] Face direction 866.8 995.0 1,032.7 1,652.1 1,790.7 Thickness direction 0.5 0.7 0.5 0.6 0.7

As shown in Table 2, the higher the pressure, the higher the thermal conductivity. It can be understood that the crucible for pressurizing according to the present invention can exert pressure on the raw material and is very effective in producing a graphite sheet excellent in thermal conductivity.

Further, the method for producing graphite of the present invention using induction heating has the following advantages in comparison with the method using other conventional heating methods (resistance heating, etc.).

① Superior economical efficiency: Induction heating is directly heated by the heating body itself, so the efficiency is high. In particular, unlike the conventional resistance heating method, the sheet itself is heated (generated) by graphite (crystallization) due to the principle of induction heating, and the cost required for ultra-high temperature heating is lower, Method can be lowered to half or less.

② Ensuring high quality: If you choose appropriate frequency according to material and size of material to be heated, uniform temperature and speed can be controlled arbitrarily, so it is possible to produce individual parts by mass production Possible is an absolute requirement for heat treatment technology).

(3) Non-contact heating: It is possible to completely separate / block the heating object from the heating source, thereby preventing various kinds of contamination (heating at 3000 ℃ or higher and heating in various gas atmosphere or vacuum).

④ Rapid work process in seconds: induction heating can be processed in most seconds. Such rapid processing prevents the material from changing in material, and when mass production such as automation parts is required, it is possible to introduce a system capable of adjusting the production speed with respect to the front and rear processing, It is a big advantage compared to.

⑤ Reduction of material: By using induction heating, it is possible to heat efficiently and to save material.

⑥ Non-pollution: Hygienic work is possible because it is completely pollution-free industry.

⑦ Increase of operation efficiency: Preliminary time such as preheating is unnecessary, and the operation rate of equipment is increased.

⑧ Installation site: It does not occupy much installation area compared to the output.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

100: Pressurized crucible
200: crucible body
300: crucible cap
310: Support of the crucible cap
320: body portion of crucible cap
400: threads formed in the crucible body
500: thread formed in crucible cap
600: firing furnace for producing graphite
610: induction heating coil
630: Insulation
700: raw material (raw film)

Claims (13)

(a) a threaded upper open crucible body screwable with the crucible cap on all or a portion of the inner side surface of the opening; And
(b) a screw-formed crucible cap which can be threadably engaged with the inner side of the opening of the crucible body on the outside,
At this time, either or both of the inner bottom of the crucible body and the lower end of the crucible cap is in the form of a generally convex curved surface having a radius of curvature of 10 cm to 1000 cm from the center of the curved inner diameter,
Wherein the raw material is charged into the crucible body and the raw material can be pressed by locking the crucible lid to lock the crucible for producing graphite.
delete delete delete The method according to claim 1,
And a hole penetrating through a side surface of the crucible body or passing through the crucible cap is formed.
(a) a threaded upper open crucible body screwable with a crucible cap on a portion of the outer side of the opening; And
(b) a crucible cap having a threaded support that can be threadably engaged with the outer side of the opening of the crucible body and a body threadedly engaged with the support,
At this time, the wall thickness of the crucible is 0.1 to 5 times the delta defined by the following formula (1)
Wherein the raw material is charged into the crucible body and the raw material can be pressurized by rotating the body portion of the crucible lid to lock the crucible for producing graphite.
[Equation 1]

Where _r is the resistivity (Ω · m) of the crucible, f is the frequency (Hz) of the induction heating current, μ _R is the relative permeability of the crucible, μ ₀ is the vacuum permeability (4π × 10 ^-7 H / m).
7. The method according to any one of claims 1, 5 and 6,
Wherein the crucible is made of a material containing graphite and has a wall thickness of 1 mm to 200 mm.
delete 6. The crucible of any one of claims 1 to 5,
A heat insulating material including porous graphite surrounding all or part of the outside of the crucible;
An induction heating coil located outside the heat insulating material; And
And a current generator for flowing an alternating current of 50 Hz to 400 kHz to the induction heating coil.
delete delete delete (a) charging the raw material into the crucible of any one of claims 1, 5 and 6; And
(b) subjecting the raw material to heat treatment to graphitize the raw material,
Wherein the heat treatment in the step (b) is performed by induction heating the raw material simultaneously or sequentially with the induction heating of the crucible.

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