KR20120102425A - Manufacturing method of insulation material using infusible carbonous fibers - Google Patents

Abstract

PURPOSE: A manufacturing method of heat insulating materials using stabilized carbonaceous fiber is provided to enhance thermal insulation, heat resistance, durability, mechanical strength and oxidation resistance by manufacturing molded products and performing coating or welding of graphite. CONSTITUTION: A manufacturing method of heat insulating materials using stabilized carbonaceous fiber comprises the following steps: manufacturing carbon fiber having an average length of 0.1-10mm by chopping and non-deliquescing after spinning a carbonaceous fiber precursor; manufacturing a dispersed solution by dispersing the carbonaceous fiber with a binder into a solvent; manufacturing a molded product by pouring the dispersed solution into a molding frame; carbonizing the molded product; and attaching a graphite material after coating the surface of the molded product with a coating agent or spreading the surface with adhesive. The carbonaceous fiber precursor is one or more kinds selected from poly acrylonitrile, phenol resin, layon, cotton, petroleum pitch and coal pitch. The non-deliquescence is processed at 100-400 deg. Celsius. The coating agent comprises 10-200 parts by weight of graphite powder, 5-10 parts by weight of surface modifier, 100-700 parts by weight of solvent based on 100 parts by weight of the resin.

Description

Manufacturing method of Insulation material using Infusible carbonous fibers

The present invention relates to a method for producing a carbonaceous heat insulating material excellent in heat insulation, heat resistance, durability and mechanical strength.

In order to maintain the furnace core temperature in a high temperature furnace, graphite powder or alumina-based ceramic insulation is used for the inner wall of the furnace. However, they are difficult to obtain uniform thermal insulation, and in particular, when used in a furnace of a non-oxidizing atmosphere that requires a shielding structure from the outside air, they have a very complicated defect, and therefore, carbon fiber, ceramic fiber, and rock wool Inorganic fibers with excellent heat resistance, etc.) have been manufactured in the form of bulky felts and molded and used widely as insulation materials.

However, with the recent technological development of materials manufactured at high temperatures and the growth of the solar cell and semiconductor markets, there is a need for insulating materials that can be used at high temperatures. Furthermore, in the field of metal single crystal production, high purity with few impurities such as metal atoms and ceramics other than the metal to be produced is required. Therefore, carbon fiber-based insulation that can withstand high temperatures of 3000 ° C. or higher and can be manufactured with high purity is mainly used. The carbon fiber-based insulation has a bulk density of 0.3 g / cm ³ or less, and molded insulation has become mainstream.

Conventional molded insulation materials for non-oxidizing atmospheres are usually produced by two methods. One of them is a method of needle-punching a random web of carbon fibers to produce a carbon fiber felt, impregnating the resin with a resin, laminating, curing and carbonizing. However, when the carbon fiber felt is laminated and used, the needle punched carbon fiber is perpendicular to the laminated surface, so when used as a heat insulating material, heat is increased along the carbon fiber in the vertical direction or the temperature inside the furnace is unevenly fired. It has the disadvantage of affecting water. In addition, because the felt is manufactured through a fiberization process such as cross lapping, opening, carding, and needle punching to produce the felt, a long manufacturing process and a high manufacturing cost are introduced. have.

In another method of making a heat insulating material, Japanese Unexamined Patent Application Publication No. 5-43320 has a molded article obtained by suction molding a slurry including a carbon fiber aggregate having a mean fiber length of 0.1 to 1 mm, a thermosetting binder, and a thermoplastic binder in a mold. A method for producing a carbonaceous molded body by heating is provided. However, the carbon fiber used in the manufacturing method is manufactured through carbonization or a graphitization step if necessary, and the chopping step for obtaining the length of the fiber is performed after carbonization or graphitization. Therefore, the material of the knife or chopper to be used is a material that is higher than or equal to the strength of the carbon fiber is expensive and has a short life.

Therefore, the inventors of the present invention have solved the above problems, and as a result, obtain a molded body using the incompatible carbonaceous fiber obtained during the carbon fiber manufacturing process, and then coat the surface with a coating or graphite to further strengthen the thermal insulation properties. When the substrate is attached, it has been found that a carbonaceous molded insulating material having a long life, easy handling and excellent independence can be manufactured with a simple process and low cost, thereby completing the present invention. That is, an object of the present invention is to provide a method for producing a heat insulating material for a high temperature treatment furnace.

The present invention

Spinning the carbon fiber precursor, and then chopping and infusifying the carbonaceous fiber having an average fiber length of 0.1 to 10 mm;

Dispersing the carbonaceous fibers in a solvent together with a binder to prepare a dispersion;

Pouring the dispersion into a mold to produce a molded body;

Carbonizing the molded body; And

Coating the surface of the carbonized molded body with a coating or applying an adhesive to the surface and attaching a graphite substrate;

Characterized in that the manufacturing method of the insulating material comprising a.

According to the insulating material manufacturing method of the present invention, since the carbonaceous fiber is used only until the insolubilization step, the carbonaceous fiber can be easily processed to a desired length using a chopper of a general-purpose material, and it does not go through a mat or felt form. Insulating materials can be manufactured in a simple process. In addition, the combination of the average fiber length of the carbonaceous fiber has the advantage of controlling the properties of the heat insulating material, it is possible to obtain a heat resistance reinforced by oxidation resistance through the adhesion of the coating or graphite substrate. The manufactured heat insulating material can be usefully applied as a heat insulating material in high temperature treatment furnaces such as vacuum furnaces, semiconductor single crystal growth furnaces, ceramic sintering furnaces, carbon-carbon composite firing furnaces, and metal treatment furnaces in fields such as semiconductors and functional ceramics.

Hereinafter, the present invention will be described in more detail.

The present invention is a method for producing a carbonaceous heat insulating material by dispersing the infusible carbonaceous fibers in a solvent with a binder, forming them into a molded body, and then coating the surface of the carbonized molded body with a coating or bonding a graphite substrate to the surface It is about.

The biggest feature of the present invention is the use of infusible carbonaceous fibers, not carbon fibers produced through the carbonization process. Carbon fibers are usually manufactured by spinning a precursor to fiberize, followed by infusibilization and carbonization. After carbonization, it may be graphitized if necessary. The carbon fiber has a problem that the manufacturing cost increases because the carbon fiber has a very high strength and uses an expensive specially coated blade or a blade of a special material to cut the carbon fiber during the chopping process. However, in the present invention, before the carbonization process, the carbonaceous fiber is prepared through the infusibilization step, and the carbonaceous fiber is easy to cut because of low strength and does not undergo the carbonization process, thereby increasing process efficiency. There is an advantage. As such, the carbonaceous fibers used in the present invention are completely different from the coarse carbon fibers up to the carbonization process. In addition, the felt-type heat insulating material using a conventional carbon fiber requires a process such as opening, carding, needle punching to make the felt, carbonaceous fiber is low in strength and easy to break during the felt manufacturing process. Therefore, in this invention, it is characterized by manufacturing a heat insulating material by the manufacturing method of the molded object using a molding die.

First, spinning the carbon fiber precursor, and then chopping and infusible to perform a step of producing a carbonaceous fiber having an average fiber length of 0.1 ~ 10 mm. The carbon fiber precursor may be used at least one selected from polyacrylonitrile, phenol resin, rayon, cotton, petroleum pitch, and coal pitch. It is preferable to use isotropic pitch rather than anisotropic pitch. The spun carbonaceous fibers are collected on the porous belt, chopped to the desired length, and immobilized in a continuous oxidation furnace. At this time, the infusion furnace may be a continuous furnace that proceeds in a belt form or a rotary cylindrical continuous infusion furnace such as a cylindrical rotary kiln, and the temperature in the furnace is preferably maintained at 100 to 400 ° C.

The average fiber length of the carbonaceous fibers is preferably 0.1 to 10 mm, preferably 1 to 6 mm. If the average fiber length is less than 0.1 mm may have a problem that the bulk density is increased and thus the thermal insulation is lowered, if it exceeds 10 mm there may be a problem that the carbonaceous fiber dispersion is not good. In addition, the length of the fiber can be used in combination of carbonaceous fibers of different lengths in the range that can be controlled moldability and apparent density. Preferably, the average fiber length is 0.1-1 mm and 1-6 mm in combination. As the proportion of carbonaceous fibers with short average fiber length increases, the bulk density and mechanical strength of the molded body increase. Therefore, by adjusting the average fiber length ratio of the carbonaceous fibers used, it is possible to control the bulk density and mechanical strength of the molded body.

Thereafter, the carbonaceous fibers are dispersed in a solvent together with a binder to prepare a dispersion. The kind of binder can be selected according to the use of a molded object, and the binder which can be carbonized or graphitized is used. The binder may be liquid, powder or fibrous, but it is convenient to use liquid. Examples of the binder that can be used include at least one selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, and sucrose. Preferably phenol resins are suitable. Content of a binder can be suitably selected according to apparent density etc. in the range which does not impair uniform mixing of a carbonaceous fiber and a binder. For example, 5-50 weight part with respect to 100 weight part of carbonaceous fibers, Preferably 15-45 weight part is good.

As the solvent, an organic solvent may be used, but in consideration of the working environment and convenience, it is preferable to use water or a solvent containing water as a main component. Moreover, the dispersion liquid which disperse | distributed carbonaceous fiber and a binder in the solvent may contain additives, such as a thermoplastic resin, a dispersing agent, a stabilizer, a viscosity modifier, an antisettling agent, a flocculant, surfactant, in the range which does not affect the characteristic of a molded heat insulating material. .

Thereafter, the dispersion is poured into a mold to prepare a molded body. To produce the shaped body, the dispersion is first fed into the mold and then the solid phase components are deposited. The mold includes a plurality of mesh nets for preventing the passage of solid phase components, and in order to allow the liquid phase components to fall out more, a pressure reducing means such as a suction pump or a press plate such as a press may be used. You can also squeeze it out. The molding die may be flat or cylindrical. Next, the molded product is manufactured by releasing and releasing the mold release product from the molding mold by heating and drying, or by drying the cured components by drying the mold itself and then releasing it.

The molded article released from the mold is carbonized and hardly remains any material other than the simple elements. Carbonization of the molded body is preferably carried out in an inert gas atmosphere such as nitrogen (N ₂ ), helium (He), argon (Ar) or under a vacuum. In addition, the heat insulating material subjected to the carbonization process may be subjected to graphitization treatment as necessary. In the case of graphitizing treatment, it is preferable to perform at 2000 ℃ or more.

When the carbonized molded body is directly used as a heat insulating material, there is a problem that carbonaceous fibers are oxidized by contact of gas and carbonaceous fibers in the furnace. For example, SiO gas generated in the silicon growth furnace is in contact with the carbonaceous fibers to produce SiC or converted to CO, which reduces the life and insulation performance of the insulation. Therefore, in the present invention, the surface of the carbonaceous fiber obtained through carbonization is coated with a coating agent, or by applying an adhesive to the surface and attaching a graphite substrate to lower the gas permeability to prevent oxidation of the carbonaceous fiber, scattering of the oxidized fiber Prevents heat, and further enhances the thermal insulation performance against radiant heat.

The coating agent includes a resin which can be carbonized or graphitized and has a high carbonization yield, a graphite powder, a surface improving agent, and a solvent. As the resin having a high carbonization yield, for example, one or more selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, and sucrose can be used, and preferably a furan resin is suitable. In addition, the coating agent is characterized in that it contains a graphite powder to reduce the pores on the surface of the heat insulating material to obtain the antioxidant effect of the carbonaceous fiber. As the graphite powder, one or more selected from artificial graphite, impression graphite, earth graphite and carbon black may be used, and those having different particle sizes are preferably used in combination. Preferably, it is preferable to use a combination of impression graphite having an average particle diameter of 10 to 150 µm and 1 to 10 µm. The amount of the graphite powder is 10 to 200 parts by weight, preferably 70 to 150 parts by weight with respect to 100 parts by weight of the resin. If the content of the graphite powder is less than 10 parts by weight, there may be a problem that the graphite coating is not sufficiently made, if the content is more than 200 parts by weight the surface is rough and there may be a problem of poor workability. As the surface improving agent, one or more selected from methyl cellulose, ethyl cellulose and methyl ethyl cellulose may be used, and preferably, methyl cellulose is used. It is preferable to use 5-10 weight part with respect to 100 weight part of resins for a surface improving agent. Solvents can dissolve surface improvers and disperse or dissolve resins and graphite powders. Water, ethanol, methanol, isopropyl alcohol, 2-furylmethanol, butyldiglycol, acetone And one or more selected from methyl ethyl ketone can be used. The content of the solvent is 100 to 700 parts by weight, preferably 300 to 600 parts by weight based on 100 parts by weight of the resin.

The coating agent is coated by a brush or a sprayer on one side, both sides, or the entire surface of the insulation. The coating amount of the coating agent is preferably 500 to 2000 g / m ² , and more preferably 700 to 1500 g / m ² . Insulating material coated with a coating is cured, carbonized, and graphitized as necessary. As a result, almost no material other than carbon remains.

Another method for attaching the graphite substrate, which is a surface treatment method, is to apply an adhesive on a heat insulating material to attach the graphite substrate to increase oxidation resistance and strength.

The adhesive includes a resin, carbon fiber, and a solvent that can be carbonized or graphitized and have a high carbonization yield. The resin which can be used can use 1 or more types selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, a polyurethane resin, and sucrose, Preferably a phenol resin is preferable. The form may be in powder or liquid form, or may be mixed and used. In addition, carbon fibers are contained in the adhesive to obtain the effect of increasing the surface area bonded to the graphite substrate. The carbon fiber used has an average fiber length of 0.01 to 2 mm, preferably 0.05 to 1.0 mm, more preferably 0.1 to 1 mm. If the average fiber length is more than 2 mm, there is a problem that the surface is uneven when applying the adhesive due to agglomeration of the fiber. The content of the carbon fiber having the average fiber length in the above range is 10 to 60 parts by weight, preferably 30 to 50 parts by weight with respect to 100 parts by weight of the resin. The solvent may be any heterocyclic compound capable of dissolving the resin, but may be any one of three-membered ring, four-membered ring, and five-membered ring, but preferably 2-furyl in which the element constituting the ring is oxygen. It is preferred to use methanol (2-furylmethanol), furan-2-carbaldehyde or mixtures thereof. The solvent can also use what mixed diluents, such as water, alcohol, and ketones. The total content of the solvent including the diluent is preferably 10 to 100 parts by weight, more preferably 30 to 80 parts by weight based on 100 parts by weight of the resin.

The prepared adhesive is applied to the end or both sides of the heat insulating material through a brush (brush), etc., the amount applied is preferably 100 ~ 1000 g / m ² , more preferably 300 ~ 800 g / m ^{2 It} is. Thereafter, the graphite substrate is adhered on the applied adhesive. As the graphite substrate, graphite sheet, carbon fiber fabric or carbon fiber paper can be used, and the heat insulating material to which the graphite substrate is bonded is hardened, carbonized, and graphitized as necessary, and finally, a product in which few substances other than carbon remain. You can get it.

According to the insulating material manufacturing method of the present invention, since the carbonaceous fiber is used only until the insolubilization step, the carbonaceous fiber can be easily processed to a desired length using a chopper of a general-purpose material, and it does not go through a mat or felt form. Insulating materials can be manufactured in a simple process. In addition, the surface-treated carbonized molded body prevents gas permeation and fiber scattering and exhibits excellent heat insulating properties. Thus, the manufactured heat insulating material has a vacuum furnace, semiconductor single crystal growth furnace, and ceramic sintering in fields such as semiconductors and functional ceramics. It can be usefully applied as a heat insulator in a high temperature treatment furnace such as a carbon-carbon composite firing furnace and a metal treatment furnace.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

[Example]

Preparation Example 1-5

After melt spinning the isotropic pitch, it was chopped at regular intervals and infused to obtain a carbonaceous fiber having an average fiber length of 0.1 to 6 mm.

The average fiber length was measured by the following method. A 30 ml Erlenmeyer flask contained 5 ml of liquid paraffin with 10 ml dropper. Samples were randomly taken from infusible carbonaceous fibers, placed in the Erlenmeyer flask, mixed and dispersed. 300 µl was taken from this dispersion, placed in two slide glasses, and pressed. The fiber length was measured using a Video Microscope Image Analyser (SOMETECH, icamcope) and the average fiber length was obtained.

The obtained incompatible carbonaceous fiber was dispersed in water together with a phenol resin (KC-6301, Gangnam Hwasung Co., Ltd.) and stirred in a water bath to prepare a uniform dispersion. The mixing ratio of the infusified carbonaceous fiber and phenol resin is shown in Table 1 below, and the weight ratio of phenol resin and water was 1:60. Thereafter, the dispersion was poured into a mold having a flat plate, pressurized with a hot press, and dried. The mold was taken out from the mold and cured by heating and drying at 150 ° C. for 2 hours to obtain a molded product. The obtained molded product was then heated to 1000 ° C. at a heating rate of 10 ° C./min in a nitrogen gas atmosphere and carbonized for 1 hour to prepare a heat insulating material.

division weight% Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Carbonaceous fiber
(0.1-1 mm) 70 50 35 20 - Carbonaceous fiber
(1-6 mm) - 20 35 50 70 Phenolic resin 30 30 30 30 30

Production Example 6

Pitch-based carbon fiber felt (Osaka Gas Chemical, S-221) with an apparent density of 0.05 g / cm ³ was impregnated and squeezed with a phenolic resin solution (KC-4300N, Gangnam Hwaseong Co., Ltd.). Cured to ℃. Thereafter, carbonization was performed at 1000 ° C. for 1 hour to obtain a felt insulation.

Example 1

100 parts by weight of impression graphite (Qingdao Kropfmuehl Graphite, QKG-298, average particle diameter 75㎛), 100 parts by weight of furan resin (Kangnam Hwaseong, KC-1009), impression graphite (Qingdao Kropfmuehl Graphite, MGF-4995, average A coating solution was prepared by uniformly mixing and dispersing 45 parts by weight of particle diameter 4 μm, 7 parts by weight of methyl cellulose (FMC-60150, Samsung Fine Chemicals Co., Ltd.), 100 parts by weight of butyl diglycol and 450 parts by weight of water. The coating solution thus prepared was applied to one side of the heat insulating material prepared in Preparation Example 4 with a brush at a rate of 1 kg / m ² , and dried and cured at 150 ° C. for 2 hours. Thereafter, carbonization was performed at 1000 ° C. for 1 hour in a nitrogen atmosphere, and then graphitized at 2000 ° C. for 1 hour in an argon atmosphere to obtain a heat insulating material.

Example 2

40 parts by weight of short carbon fiber (Kureha, M-102S, average fiber length 0.2 mm), 40 parts by weight of 2-furylmethanol and 30 parts by weight of methanol are uniformly mixed with 100 parts by weight of the powdered phenol resin (Gangnam Hwasung). And dispersion to prepare an adhesive. The prepared adhesive was applied to one side of the heat insulating material prepared in Preparation Example 4 at a rate of 450 kg / m ² and bonded with a graphite sheet (Qingdao Kropfmuehl Graphite Co., Ltd.) having a thickness of 0.38 mm. Thereafter, the mixture was cured with compression at 150 ° C. at a pressure of 0.015 MPa for 2 hours, carbonized at 1000 ° C. for 1 hour in nitrogen atmosphere, and then graphitized at 2000 ° C. for 1 hour in argon atmosphere to obtain a heat insulating material.

Comparative Example 1

In the same manner as in Example 1, the coating liquid without addition of graphite powder was coated on the surface of the heat insulating material obtained in Preparation Example 4.

Comparative Example 2

In the same manner as in Example 2, but did not use the carbon fiber adhesive was used.

Physical property test

The physical properties of the heat insulating materials prepared in Production Examples 1 to 6, Examples 1 to 2, and Comparative Examples 1 to 2 were tested by the following method.

1) apparent density

A predetermined amount of zinc chloride and 1% hydrochloric acid was weighed into a beaker and mixed to prepare a mixed solution. 500 ml of the mixed solution was transferred to a measuring cylinder, immersed in a constant temperature water bath, and adjusted to a temperature of 20 ± 1 ° C., followed by a specific gravity meter. Measured. Ten types of specific gravity solutions were prepared by appropriately changing the relative amounts of zinc chloride and 1% hydrochloric acid. Ten kinds of specific gravity liquids were slowly injected along the pipe wall into a 20 ml measuring cylinder, each of 2 ml in order of high specific gravity to make a density gradient tube.

On the other hand, 0.1 g of the heat insulating material sample which crushed with a mortar and passed the standard body of 150 micrometers mesh was disperse | distributed in a small amount of ethanol, and the sample dispersion liquid was obtained. After immersing the density gradient tube in a low temperature constant temperature bath at 20 ± 1 ° C, after 30 minutes, slowly disperse the sample dispersion into the density gradient tube and allow it to stand for at least 12 hours.Then, read the position of the sample in the density gradient tube and use the density conversion table. The density was calculated.

2) flexural strength

Five samples having a width of 10 mm, a thickness of 10 mm, and a length of 100 mm were cut from the manufactured insulation to prepare a test specimen for bending strength test. Samples were subjected to flexural testing using a UTM (Universal Testing Machine, Daekyung Tech, DTU-90) with 80 mm span span, 1.0 mm / min crosshead speed, and centralized loading. Flexural strength was obtained based on the maximum breaking load.

3) compressive strength

Five samples having a width of 10 mm, a thickness of 10 mm, and a length of 10 mm were cut from the manufactured insulation to prepare a test specimen for flexural strength. The sample was subjected to a uniaxial compression test using the UTM with a load cell of 50 kg and a crosshead speed of 5 mm / min. It was.

4) thermal conductivity

The thermal conductivity measurement method is a heat flow meter (Heat flowmeter) method widely used for insulation. The thermal conductivity was obtained by inserting a sample between two main heating plates and calculating the amount of heat passing through a heat flux transducer.

5) Oxidation Resistance

Specimens made of 100 mm × 100 mm × 40 mm were placed on four small cylinders in a quartz box equipped with a gas pipe, and a quartz box containing the sample was installed in a muffle furnace. Thereafter, the inside of the quartz box was replaced with nitrogen, the temperature was raised to 600 ° C, and 2 L / min of air was introduced at 600 ° C for 5 hours. The atmosphere in the quartz box was then replaced with nitrogen again and naturally cooled to 150 ° C. The quartz box was taken out of the furnace, placed in a dryer, cooled to room temperature, and weighed to 0.1 mg with an electronic balance, and the weight loss rate before and after the experiment was determined according to the weight loss method. In the same manner, the weight reduction rate by oxidation at 600 ° C. for 10 hours was also determined.

division Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Apparent density
(g / cm ³⁾ 0.3 < 0.26 0.20 0.17 0.13 0.13 Flexural strength
(MPa) 1.42 1.35 1.12 1.01 0.62 0.75 Compressive strength
(MPa, 5% deformation) 0.34 0.26 0.20 0.17 0.12 0.11 Thermal conductivity
(Wm ^-1 K ^-1 at 25 ℃) 0.29 0.26 0.18 0.16 0.15 0.17

Infusable carbonaceous fibers have a disadvantage of poor workability due to their weak strength. That is, the fiber breaks during the manufacturing process, increasing the bulk density and increasing the thermal conductivity. However, as shown in Table 2, the heat insulating material obtained in Preparation Examples 1 to 5 exhibits the same mechanical properties and thermal conductivity as those of Preparation Example 6 coated with a phenolic resin on carbon fiber felt, even though incompatible carbonaceous fibers were used. It was. This result shows that the breakage of the fibers is minimized by processing the incompatible carbonaceous fiber into a molded body using a mold rather than a felt type, and it can be seen that the existing carbon fiber insulation can be replaced with the incompatible carbonaceous fiber insulation. . In addition, it can be seen that it is easy to chop and simplify the process because it uses the infusible carbonaceous fibers before the carbonization process.

division Production Example 4 Example 1 Example 2 Comparative Example 1 Comparative Example 2 Flexural strength
(MPa) 1.01 1.45 2.12 1.02 2.08 Compressive strength
(MPa, 5% deformation) 0.17 0.26 0.43 0.18 0.36 Oxidation resistance
(Weight loss rate,%) 5 hours 5.0 2.2 1.0 4.7 2.6 10 hours 8.2 5.6 1.8 8.1 3.0

Table 3 shows the effect of improving the mechanical strength and oxidation resistance of the insulation according to the surface treatment. As shown in Table 3, it can be seen that when the surface of the insulation is coated with a coating agent or a graphite base is attached, the weight loss rate is significantly lowered. This is because the oxidation of the fiber is suppressed by forming a dense material such as a coating agent or a graphite sheet on the surface of the heat insulating material by surface treatment to prevent contact between the carbonaceous fiber and the gas in the furnace. That is, the surface treatment can improve the thermal insulation performance against radiant heat, reduce the gas permeability to prevent the carbon fiber from being oxidized, and prevent the oxidized carbon fiber from scattering and falling into the product.

In Comparative Example 1 using a coating agent containing no graphite powder, most of the coating agent was absorbed into the heat insulating material, so that the pores on the surface could not be effectively filled, and the surface was uneven after carbonization. Due to this, the effect of improving the oxidation resistance was less than that of Example 1. In the case of Comparative Example 2, which does not contain carbon fiber in the adhesive when the graphite sheet is attached, the graphite sheet swells or a part is dropped during the carbonization process. The results were only 2.6 ~ 3.0%.

As a result, according to the manufacturing method of the heat insulating material of the present invention, it is possible to obtain a carbonaceous heat insulating material excellent in heat insulation, heat resistance, durability and mechanical strength, so that in the field of semiconductor and functional ceramics, vacuum furnace, semiconductor single crystal growth furnace, ceramic sintering furnace, It was confirmed that the carbon-carbon composite firing furnace, the metal treatment furnace, etc. can be applied as a heat insulating material in high temperature treatment furnace.

Claims (15)

Spinning the carbon fiber precursor, and then chopping and infusifying the carbonaceous fiber having an average fiber length of 0.1 to 10 mm;
Dispersing the carbonaceous fibers in a solvent together with a binder to prepare a dispersion;
Pouring the dispersion into a mold to produce a molded body;
Carbonizing the molded body; And
Coating the surface of the carbonized molded body with a coating or applying an adhesive to the surface and attaching a graphite substrate;
Method for producing a heat insulating material comprising a.
The method of claim 1, wherein the carbon fiber precursor is at least one selected from polyacrylonitrile, phenol resin, rayon, cotton, petroleum pitch and coal pitch.
The method of claim 1, wherein the incompatibility is performed at 100 to 400 ° C. 3.
The method of claim 1, wherein the carbonaceous fiber is a mixture of the average fiber length is 0.1 ~ 1 mm and 1 ~ 6 mm.
The method of claim 1, wherein the binder is at least one selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, and sucrose.
According to claim 1, wherein the coating agent is 10 to 200 parts by weight of graphite powder with respect to 100 parts by weight of the resin; 5 to 10 parts by weight of the surface improver; And 100 ~ 700 parts by weight of the solvent; manufacturing method of a heat insulating material comprising a.
7. The method of claim 6, wherein the resin is at least one selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, and sucrose.
The method of claim 6, wherein the graphite powder is at least one selected from artificial graphite, impression graphite, earth graphite, and carbon black.
The method of claim 6, wherein the surface improving agent is at least one selected from methyl cellulose, ethyl cellulose and methyl ethyl cellulose.
The method of claim 6, wherein the solvent is at least one selected from water, ethanol, methanol, isopropyl alcohol, 2-furylmethanol, butyldiglycol, acetone, and methyl ethyl ketone.
According to claim 1, wherein the adhesive is 10 to 60 parts by weight of carbon fiber based on 100 parts by weight of the resin; And 10 to 100 parts by weight of the solvent; manufacturing method of a heat insulating material comprising a.
12. The method of claim 11, wherein the resin is at least one selected from a phenol resin, a furan resin, an impregnation pitch, an epoxy resin, a vinyl ester resin, a polyurethane resin, and sucrose.
12. The method of claim 11, wherein the carbon fiber has an average fiber length of 0.01 to 2 mm.
12. The method of claim 11, wherein the solvent is 2-furylmethanol, furan-2-carboxaldehyde or a mixture thereof.
The method of claim 1, wherein the graphite substrate is a graphite sheet, carbon fiber fabric or carbon fiber paper.