JP2980779B2 - Flexible graphite that does not cause stable swelling and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a stable, non-bulging, flexible graphite foil structure and a method for producing a stable, non-bulging, flexible graphite foil structure.

[0002]

BACKGROUND OF THE INVENTION As used herein, the term "flexible graphite" penetrates into the crystal structure of graphite,
Exfoliated reaction product obtained by rapidly heating graphite particles that have been treated with a chemical that causes the particles to expand at least 80 times or more in a direction perpendicular to the crystalline carbon layer. Flexible graphite is a thin sheet with a density close to the theoretical density (hereinafter referred to as "foil")
But can be compressed to about 11 for most applications.
A density of 21 kg / m ³ is sufficient.

[0003] Flexible graphite is particularly useful in high temperature applications because it has a significant degree of anisotropic and thermal insulating properties. However, upon rapid exposure to high temperatures, flexible graphite foils can cause harmful surface deformations in the form of blisters. Swelling occurs on the surface of flexible graphite when the diffusion of thermally activated moisture adsorbed in the crystal structure is too slow to prevent the build-up of desorbed gas pressure. This causes the carbon layer plane to peel off on the surface of the foil, causing the foil to swell. One way to minimize or eliminate blistering is to adjust the physical parameters of the foil to facilitate ventilation of thermally desorbed moisture. This can be accomplished by piercing the foil, as disclosed in U.S. Pat. No. 4,752,518. Alternatively, the foil density or thickness can be varied such that the foil is less dense and / or thinner than the standard. Since these physical methods change the desired physical properties of the foil and affect its thermal insulation properties,
Not preferred. The thermal environment to which the foil is exposed can also be adjusted, but this will minimize the usefulness of the foil.

[0004]

SUMMARY OF THE INVENTION In accordance with the present invention, the surface chemistry of a foil is altered in order to eliminate or minimize the amount of water adsorbed in the graphite foil. This is achieved by converting the graphite foil surface to a stable hydrophobic surface that prevents blistering.

[0005] When the amount of adsorbed moisture exceeds the threshold value of the adsorbed moisture, blistering occurs in the heated flexible graphite foil. The threshold for causing the swelling of the absorbed moisture depends on the foil, the thickness of the foil,
It is a function of many physical variables such as density, rate of temperature rise from room temperature, and maximum heating temperature. If the amount of moisture released from the heated foil is higher than the adsorbed moisture threshold, the foil will blister. Conversely, if the amount of moisture released is below the adsorbed moisture threshold, the foil will not blister. The amount of water adsorbed on the foil depends on the surface chemistry of the foil and on environmental conditions such as relative humidity.

According to the present invention, the surface chemistry of the foil is modified to minimize the amount of water adsorbed. This is achieved by two chemical reactions that convert the graphite foil surface from an acidic, hydrophilic surface to a basic, stable, hydrophobic surface that prevents blistering. The first chemical reaction is
A high temperature heat treatment for at least 600 ° C., preferably over 800 ° C. for a certain period of time to convert acidic and hydrophilic surface functional groups (eg carboxylic acid, lactone, hydroxyl and carbonyl groups) to basic and hydrophobic functional groups. It is. This heated foil does not blister for a short period of months, but its active sites react slowly in air unless a second chemical reaction is performed in a timely manner to stabilize the graphite surface. , Causing swelling. In the second chemical reaction, which is a stabilization reaction, a chemical is added to active sites on graphite generated by high-temperature heat treatment. Hydrophobic functional groups are introduced by the reaction between the active site and a chemical such as hydrogen, chlorine, hydrochloric acid, nitric acid-hydrochloric acid, or phosphoric acid,
It prevents the active sites from reacting slowly in air (hydrophilic reaction) and prevents the foil from returning to the blistering foil in about 1 to 3 months.

The active sites behave like unsaturated or olefinic double bonds and react with oxygen and water in the air to form oxirane rings, alcohols and glycols. These functional groups are hydrophilic in nature and themselves promote water adsorption and significant gassing. The reaction between the active sites and the chemicals that add hydrophobic functional groups to the graphite surface stabilizes the foil surface and keeps the amount of adsorbed water below the foil threshold.

[0008]

SUMMARY OF THE INVENTION The first method of the present invention for forming a stable, non-bulging, flexible graphite foil structure is to impregnate raw graphite particles with an impregnating agent. 10 particles
Exfoliating to a specific volume greater than 0 cm ³ / g, compressing the exfoliated graphite particles into a flexible graphite structure;
Heat treatment at a temperature of 00 ° C. for a period of 30 minutes to 5 seconds depending on the heat treatment temperature selected, and the heat treatment of the flexible graphite structure to H ₂ , Cl ₂ , Br ₂ ,
And exposed to the stabilizing agent selected from the group consisting of consisting of F ₂ but, 600 ppm elemental bromine graphite structure, fluorine and phosphorus concentration, respectively, 1
B so that it becomes 50 ppm and 600 ppm or less
each step of selecting the chemical concentration of r ₂ , F ₂ and H ₃ PO ₄ . The second method of the present invention for forming a stable, non-swelling, flexible graphite foil structure comprises a step of impregnating raw graphite particles with an impregnating agent, and a step of impregnating the impregnated graphite particles with 100 cm ^3.
Exfoliating the graphite particles to a flexible graphite structure, compressing the exfoliated graphite particles into a flexible graphite structure at least 600 g / g.
° C for 30 minutes to 5 minutes depending on the heat treatment temperature selected.
A step of a predetermined time heat treatment seconds, the heat-treated flexible graphite structure, HCl, HNO _3-HCl and H
Exposed to a stabilizer selected from the group consisting of ₃ PO _{4, wherein the} concentration of elemental bromine, fluorine and phosphorus in the graphite structure is 600 ppm,
B so that it becomes 50 ppm and 600 ppm or less
selecting the chemical concentrations of r ₂ , F ₂ and H ₃ PO ₄ , and performing a second heat treatment at a temperature above 600 ° C. on the flexible graphite structure.

The stable, non-swollen, flexible graphite foil structure of the present invention is a graphite having a density of greater than 1121 kg / m ³ and a crystal structure containing a hydrophobic functional group of a drug chemically bonded to its surface. It consists of a material from which particles have been exfoliated, the chemicals being hydrogen, hydrogen chloride, chlorine,
Each of elemental bromine, fluorine and phosphorus contained in the graphite foil structure is selected from the group consisting of bromine, fluorine, phosphoric acid and hydrogen chloride-nitric acid.
ppm, 150 ppm, and 600 ppm.

[0010] Flexible graphite first treats the graphite flakes with a chemical that penetrates into the crystal structure of the graphite and reacts to form a compound of graphite and the infiltrate. Heating to a high temperature causes the impregnation in the graphite crystals to generate gas, thereby separating the graphite layers and accumulating graphite flakes in the accordion direction in the c-direction, that is, at right angles to the graphite crystal plane. That is, it peels. Exfoliated graphite flakes are elongated in appearance and are therefore commonly referred to as worms. Next, these worms are compressed into a sheet. Unlike the original graphite flakes, this sheet is flexible and can be formed and cut into various shapes.

A general method for making graphite foil from flexible graphite is described in US Pat. No. 3,404,061 to Shane et al., Which is incorporated herein by reference.
It is described in the specification. In an exemplary embodiment of the Shane et al. Method, natural graphite flakes are impregnated by dispersing the flakes in a solution containing an oxidizing agent, such as a mixture of nitric acid and sulfuric acid. In the method of the present invention, natural graphite flakes with low ash content are preferred over flakes with high ash content. After impregnation of the flakes, excess solution is removed from the flakes. The amount of impregnating solution retained on the flakes after removal is
Generally 1 per 100 parts by weight of graphite flake
00 parts by weight solution (pph), more usually 100 parts by weight.
~ 150 pph.

After washing with water, the impregnated flakes are dried and exfoliated into flexible graphite by exposure to a flame at a temperature above 700 ° C., more usually 1000 ° C. or more, for 1 second or less. The exfoliated graphite flakes are then compressed and rolled into a densely packed graphite foil sheet having the desired density and thickness. Alternatively, as disclosed in U.S. Pat. No. 4,895,713, incorporated herein by reference, the amount of impregnating solution is limited to 10 to 50 parts of solution per 100 parts by weight of graphite (pph) and the washing step is performed. Can also be omitted.

[0013] The impregnating solution of the present invention comprises an oxidizing agent and other
Includes impregnating agents known in the art. Examples include solutions containing oxidizing agents and oxidizing mixtures, such as solutions containing nitric acid, potassium chlorate, chromate, potassium permanganate, potassium chromate, potassium dichromate, perchlorate, etc.
Or, for example, a mixture of concentrated nitric acid and chlorate, chromic acid and phosphoric acid, sulfuric acid and nitric acid, or a mixture of a strong organic acid, such as trifluoroacetic acid, and a strong oxidizing agent soluble in the organic acid.

In a preferred embodiment of the invention, the solution comprises sulfuric acid or sulfuric and phosphoric acid and an oxidizing agent, ie, nitric acid, perchloric acid, chromic acid, potassium permanganate, hydrogen peroxide, iodic acid or periodate. A mixture with an acid, etc. Although less preferred, the impregnating solution of the present invention comprises:
Metal halides such as ferric chloride mixed with ferric chloride and sulfuric acid, or halides such as bromine as a solution of bromine and sulfuric acid or bromine in organic solvents can be included.

[0015] Dried or undried impregnated flakes are prepared by a conventional method in which the flakes are rapidly heated in a flame to a temperature of more than 700 ° C, preferably more than 1000 ° C, for a time of 1 second or less. Can be peeled. A standard peel time of about 1 second at high temperatures (above the Bunsen burner flame temperature) is too short to convert acidic hydrophilic surface groups on graphite to basic hydrophobic groups. Therefore, the peeling step alone cannot function as the first high-temperature chemical reaction heat treatment of the present invention. The exfoliated graphite is then compressed into a flexible graphite sheet or foil. A preferred exfoliation method and method for compressing exfoliated graphite flakes into thin foils is described in US Pat. No. 3,404,404 to Shane et al., Supra.
No. 061. Of course, it is common to roll and compress the exfoliated worm with the product of the first stage compression, known in the art as a "low density mat". The mat is then compressed into standard density foil.

A stable, non-bulging, flexible graphite foil is produced according to the invention by performing two chemical reactions on graphite particles. The flexible graphite foil is aged for a long period of time, for example first 12 months, and then, after rapidly heating the foil with a Bunsen burner flame (900 ° C. to 950 ° C.), if no swelling is observed on the surface of the foil. , No blistering is expected. The two chemical reactions of the present invention can be performed separately or simultaneously, can be incorporated into the foil manufacturing process, or can be performed after foil manufacturing. The first chemical reaction is a high temperature heat treatment of standard graphite flakes, exfoliated worms, low density mats or standard density foil for a period of time depending on the heat treatment temperature. Heat treatment temperature is 9
When the temperature exceeds 00 ° C., the heat treatment is performed at the maximum temperature for 20 seconds to 5 seconds or more, while when the heat treatment is 600 ° C., a minimum of 1 to 30 minutes is required. Heat treatment is 600 ~
If between 900 ° C., the heat treatment time is between 30 minutes and 20 seconds, respectively. A preferred minimum heat treatment temperature is 800 ° C. The high temperature heat treatment converts the acidic acidic surface functional groups to hydrophobic functional groups. It can be expected that swelling of the flexible graphite foil can be reduced or suppressed only by high-temperature heat treatment. However, swelling is suppressed by heat treatment under the right conditions, but it is temporary, i.e. after a sufficient period of 1-3 months,
The foil has been found to be prone to blistering again. This mechanism can be attributed to the formation of unsaturated active sites resulting from the decomposition of the acid surface functionality present on all carbons. Upon cooling, oxygen and water in the air react at these unsaturated points to form hydrophilic functional groups.
According to the present invention, the heat-treated flexible graphite is exposed to stabilizers such as hydrogen, hydrogen chloride, chlorine, bromine, fluorine, hydrogen chloride-nitric acid and phosphoric acid. This second reaction stabilizes active sites on the graphite surface and minimizes reactions with oxygen and water in the air, thereby preventing blistering. It is believed that this second reaction adds a hydrophobic functional group to the graphite surface. A preferred stabilization treatment is hydrogenation or halogenation, preferably chlorination, wherein hydrogen molecules or chlorine or bromine molecules are chemically bound to the graphite surface. The preferred concentration of hydrogen is 10 to 30 ppm, whereas chlorine is preferably 150 to 300 ppm. When the stabilizing chemical reaction is carried out by phosphoric acid treatment, the phosphorus concentration retained in the crystal structure of the foil is higher than 200 ppm,
Should be below 0 ppm. Stabilizers should be added in limited amounts sufficient to react with the active sites created by the heat treatment. Excess chemicals are unnecessary and harmful with certain chemicals, such as bromine and fluorine. When bromine is present in an amount that exceeds the stoichiometric amount that reacts with active sites, it is physically adsorbed and penetrates into the graphite structure, causing exfoliation and blistering upon heating. Fluorine chemically reacts with non-active sites in the graphite structure when present in an amount that exceeds the stoichiometric amount that reacts with active sites.

Accordingly, the concentration of the chemical is as follows.
Should be limited to no more than 75-150 ppm for fluorine. With respect to the amount of other stabilizers in the graphite structure, 10 to 30 ppm is sufficient for hydrogen, 150 to 300 ppm is sufficient for chlorine, and 200 to 600 ppm is sufficient for phosphorus. Excess H ₂ , Cl
_2, HNO _3-HCl and HCl chemicals themselves,
Not harmful.

In order to produce a stable, non-swollen, flexible graphite, a second heat treatment is required in the following two situations: (a) the first heat treatment and the stabilization reaction are carried out with raw graphite flakes; If you do,
Or (b) the case where the first heat treatment is performed after the peeling, and the subsequent stabilization reaction uses an acidic chemical such as hydrochloric acid-nitric acid.

The purpose of the second heat treatment is to remove the hydrophilic acid introduced by the impregnating or acidic stabilizer without removing the desired hydrophobic stabilizing functional groups, such as those containing phosphorus or chlorine, from the graphite surface. The removal of the group. Therefore, the second heat treatment must be limited to a temperature below the decomposition temperature of the stabilizing functional group but above the temperature above 600 ° C. required for removal of the acid functional group. Heating at 900 ° C. for 20 seconds is sufficient to achieve these objectives. As is evident from Examples 6, 7 and 12, phosphorus and chlorine remain in the foil even after this second heat treatment.
The second heat treatment is performed at 600 to 1000 ° C. for a certain time,
At a temperature of 600 ° C., the holding time needs to be longer, and at 1000 ° C., the holding time needs to be shorter.

[0020]

The following examples illustrate the invention. For comparative purposes, the impregnation solution was prepared using reagent grade sulfuric acid (96% strength) and nitric acid (70% strength). The flexible graphite foil was 0.015 "thick and 112 in Examples 1-7 and 10-15, respectively.
Formed to a standard size of 1 kg / m ³ density, the foil thickness was 0.020 ″ in Examples 8 and 9. Samples of the manufactured flexible graphite were aged in a laboratory at room temperature. The “A” graphite flakes contain less than 1% ash, the “B” flakes contain 1-5% ash, and the “C” flakes contain more than 5% ash. The material in each example was subjected to the above-mentioned "swelling" test, and the state without the swelling was confirmed.

EXAMPLE 1 Natural graphite "C" flakes were placed in an inert atmosphere
Heated to 700 ° C. Next, chlorine gas was allowed to act on these graphite flakes for one hour. After this treatment, the sample was cooled to room temperature. The flakes are 85% by weight H ₂ S
It was impregnated with 30 pph of an impregnant consisting of O ₄ and 15% by weight of HNO ₃ . After peeling, the flakes were compressed to form a mat, and hydrogen gas was allowed to act at 630 ° C. to cool to room temperature. Then, the mat was placed in a standard size (0.01
5 "was rolled to foil thicknesses and 1121kg / m ³ density). Was tested this material after 420 days, blisters did not occur.

Example 2 Natural graphite "C" flakes were placed in an inert atmosphere
Heated to 700 ° C. Next, chlorine gas was allowed to act on these graphite flakes for one hour. After this processing,
The sample was cooled to room temperature. The flakes are 85% by weight H ₂
It was impregnated with the impregnation agent 30pph consisting SO ₄ and 15 wt% of HNO _3. After peeling, the flakes were compressed to form a mat, heated at 900 ° C. for 20 seconds, and then rolled into foil of the same standard dimensions as in Example 1. 3
Tested after 60 days, no blistering occurred. (This example is similar to Example 1 except that no additional hydrogen reaction was performed. Since the acidic sites introduced during the impregnation had to be removed, the sample was 900 deg. ° C
Was reheated. The obtained flexible graphite is 4pp
It contained less than m soluble or leachable chloride. )

Example 3 "A" flakes were impregnated with 30 pph of an impregnant consisting of 85% sulfuric acid and 15% nitric acid and then peeled. The exfoliated flakes were compressed to form a mat and hydrogenated at 1000 ° C. in an inert atmosphere. After cooling to room temperature
This mat was rolled into foil having the same standard dimensions as in Example 1. The foil did not blister after 360 days.

Example 4 (Comparative) An "A" flake was impregnated with 30 pph of an impregnant consisting of 85% sulfuric acid and 15% nitric acid. The impregnated flakes were peeled, rolled into a low density mat, and then heated in a Bunsen burner flame at 900 ° C. for 20 seconds.
The material did not blister initially, but began to blister after only 30 days. (This material was subjected to only one reaction, heat treatment. The sample returned to the blistering foil upon exposure to air.)

Example 5 (Comparative) The "A" flakes were impregnated with a 25 pph impregnant consisting of 80% sulfuric acid and 20% nitric acid and then peeled. After peeling, the obtained mat was heat-treated at 900 ° C. for 20 minutes in a flame of a Bunsen burner. The heated mat was rolled into foil of standard dimensions. The material did not blister initially but began to blister after only 60 days. (This material was subjected to only one reaction, heat treatment.)

Example 6 Low ash (0.1%) natural graphite flakes were purified by heating to 2900 ° C. on the supplier side. 5 ml of HCl solution (6 ml of 38% HCl diluted to 1000) was added to 25 g of flakes and mixed until the slurry was homogeneous.
Next, the slurry was placed on a hot plate, boiled and dried. After being impregnated with a 30 pph impregnating agent consisting of 85% sulfuric acid and 15% nitric acid, the film was peeled off. After rolling into a mat, it was heat treated in a flame for 20 minutes and rolled into foil of standard dimensions. The foil did not blister after 360 days. (This sample resulted in a stable, non-bulging, flexible graphite by two reactions.)

Example 7 25 g of "A" graphite flakes were placed in a 100 ml porcelain crucible and heated in a Bunsen burner flame at 900 ° C. for 1 minute. 7.5 g (30 ppm) impregnant consisting of 85% sulfuric acid and 15% nitric acid and 0.09
g phosphoric acid was added and mixed. After peeling, the flakes were compressed into mats and heated in a Bunsen burner flame for at least 20 seconds. The mat was then rolled into standard size foil. The foil did not blister for 360 days. (This flexible graphite sample has two reactions,
That is, a heat treatment of the flakes and a stabilization reaction with phosphoric acid were performed. The final flexible graphite is 365
It contained ppm of phosphorus. )

Example 8 (Comparative Example ) Natural graphite flakes having a low ash content (0.1%) of 290
Heat to 0 ° C. to reduce ash content. 8 of this material
It was impregnated with 25 pph of an impregnant consisting of 0% sulfuric acid and 20% nitric acid. This material was dried at 100 ° C., peeled off, and the peeled flakes were dried at a density of 1121 kg / m ³ ,
Rolled into 0.020 "thick foil. This material swelled immediately after fabrication. (This flexible graphite was heat treated before the impregnation reaction; it was not flame treated after the exfoliation reaction. Swelling occurred immediately.)

Example 9 (Comparative Example) This flexible graphite was prepared by heating a foil in a flame at 900 ° C.
The same as in Comparative Example 8, except that the material was first heat treated for 20 seconds and then rolled to a 0.020 ″ thickness.
On day 0, no swelling occurred when heated in a Bunsen burner flame, but after 90 days severe swelling occurred. (The surface chemistry was changed by the flame treatment, resulting in a temporary, non-bulging, flexible graphite. This sample is a chemical such as chlorine or hydrogen that introduces a hydrophobic functional group chemically bonded to the graphite surface. Since the second stabilization reaction, which is a reaction caused by the above-mentioned reaction, was not performed, swelling occurred again.)

Example 10 (Comparative) A "C" flake was impregnated with an excess of an impregnant consisting of 92% sulfuric acid and 8% nitric acid. The impregnated flakes were peeled and then rolled into standard size foil. The foil was gradually heated in vacuum at 1200 ° C. The material did not blister initially but began to blister after only 90 days. (This material was subjected to only one reaction, heat treatment, which initially prevented blistering, but the surface was reactive and blistering occurred again.)

Example 11 "A" flakes were impregnated with an excess of an impregnant consisting of 92% sulfuric acid and 8% nitric acid. The impregnated flakes were washed, dried, peeled, and then rolled into standard size foil. This foil was gradually heated to 1700 ° C., and then chlorine gas was allowed to act. After cooling, the material did not swell after one year. This foil is 180pp
m, but leachable chlorine was less than 5 ppm.

Example 12 "A" flakes were impregnated with 30 pph of an impregnant consisting of 85% sulfuric acid and 15% nitric acid. After peeling, the flakes are compressed into a mat and placed in a Bunsen burner flame.
Heat treatment was performed for 0 seconds. The mat was then washed with 500 ml of water, 50 ml of HCl and 50 ml of HNO ₃
It was immersed in 0% aqua regia. This material was washed and dried at 130 ° C. overnight. The material was then heated in a flame for 20 seconds and rolled into standard size foil. This material is 360
No blistering occurred for days. (This material was subjected to a second high temperature heat treatment. The aqueous solution generated chlorine and chlorinated the mat. The treated mat was subjected to a second heat treatment in a Bunsen burner flame for 20 seconds, Hydrophilic acid groups generated on the surface were removed by nitric acid.)

Example 13 (Comparative Example) This example is the same as Example 12 except that the final heat treatment was not performed in a flame after the aqua regia treatment. This material immediately swelled. (This example illustrates the importance of a final heat treatment after reaction with an acidic stabilizer such as hydrochloric acid-nitric acid. A hydrophilic group was introduced by the acid. Since no heat treatment was performed later, the flexible graphite adsorbed an amount of water exceeding the swelling threshold.)

Example 14 (Comparative) 15 g of "A" flakes were prepared by adding 83% sulfuric acid, 14.5%
4.5 g of nitric acid and 2.5% phosphoric acid (30
(pph). After peeling, the material was compressed into a mat and heated in a Bunsen burner flame for 20 seconds. The mat was then rolled into flexible graphite foil. The material did not blister at first but began to blister after 120 days. (The treatment with phosphoric acid was performed before the heat treatment in the flame. Therefore, active sites generated during the heat treatment in the flame were not stabilized.)

Example 15 "B" flakes were impregnated with an excess of an impregnant consisting of 92% sulfuric acid and 8% nitric acid. The impregnated material was washed, dried, peeled, and then rolled into standard size foil. The foil was gradually heated to 1700 ° C., and then chlorine gas was allowed to act. After cooling, the material did not blister for one year. The foil contained 250 ppm chlorine and less than 5 ppm leachable chlorine.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C01B 31/04 101

Claims (29)

(57) [Claims] 1. a step of impregnating raw graphite particles with an impregnating agent; a step of separating the impregnated graphite particles into a specific volume exceeding 100 cm ³ / g; a step of compressing the separated graphite particles into a flexible graphite structure; Heat treating said flexible graphite structure at a temperature of at least 600 ° C. for a fixed time of 30 minutes to 5 seconds depending on the selected heat treatment temperature; and subjecting the heat-treated flexible graphite structure to H ₂ , Cl ₂ , Br ₂ , And F
₂ are exposed to a stabilizer selected from the group consisting of: the elemental bromine, fluorine and phosphorus concentrations in the graphite structure are 600 ppm and 150 pp, respectively.
A method for producing a stable, non-bulging, flexible graphite foil structure, comprising the steps of selecting the chemical concentrations of Br ₂ , F ₂ and H ₃ PO _{4 so} as to be at most m and 600 ppm. 2. The method according to claim 1, wherein when the heat treatment temperature is 600 ° C., the fixed time is 1 to 30 minutes. 3. The method according to claim 1, wherein when the heat treatment temperature is 600 ° C. to 900 ° C., the fixed time is 30 minutes to 20 seconds. 4. When the heat treatment temperature exceeds 900 ° C.,
The method of claim 1, wherein the fixed time is between 20 seconds and 5 seconds. 5. The exfoliated graphite particles are first compressed into a low density mat and then further into a foil, and the heat treatment step is performed after the graphite particles have been compressed into a low density mat, but further into a foil. The method according to claim 4, characterized in that it is performed on the graphite particles before they are compressed. 6. The method of claim 5, wherein the heat treated low density mat is exposed to the stabilizer before being further compressed into foil. 7. The method according to claim 6, wherein the heat treatment step and the step of exposing to the stabilizer are performed simultaneously. 8. The method of claim 5, wherein the heat treated low density mat is exposed to the stabilizer after the low density mat has been further compressed into foil. 9. The method of claim 1, wherein said heat treating step and said step of exposing to said stabilizer are applied to said compacted graphite particles after forming a foil. 10. The method according to claim 5, wherein the raw graphite particles have an ash content of less than 1%. 11. A step of impregnating the raw graphite particles with an impregnating agent, a step of exfoliating the impregnated graphite particles to a specific volume exceeding 100 cm ³ / g, a step of compressing the exfoliated graphite particles into a flexible graphite structure, Heat treating said flexible graphite structure at a temperature of at least 600 ° C. for a period of time ranging from 30 minutes to 5 seconds depending on the selected heat treatment temperature; HCl, HN
O ₃ is exposed from the group consisting of consisting -HCl and H ₃ PO ₄ in the selected stabilizer, comprising elemental bromine graphite structure, fluorine and phosphorus concentrations respectively 600ppm, 150 ppm, and 600ppm or less And selecting a chemical concentration of Br ₂ , F ₂ and H ₃ PO ₄ , and performing a second heat treatment at a temperature above 600 ° C. on the flexible graphite structure. , A method for producing a flexible graphite foil structure which does not cause swelling. 12. When the heat treatment temperature is 600 ° C.,
The fixed time is 1 to 30 minutes,
The method according to claim 11. 13. The method according to claim 11, wherein when the heat treatment temperature is between 600 ° C. and 900 ° C., the fixed time is between 30 minutes and 20 seconds. 14. The method according to claim 11, wherein when the heat treatment temperature exceeds 900 ° C., the fixed time is 20 seconds to 5 seconds. 15. The exfoliated graphite particles are first compressed into a low density mat and then further into a foil, and the heat treatment step is performed after the graphite particles have been compressed into a low density mat, but further into a foil. The method according to claim 14, characterized in that it is performed on the graphite particles before they are compressed. 16. The method of claim 15, wherein the heat treated low density mat is exposed to the stabilizer before being further compressed into foil. 17. The method according to claim 16, wherein the heat treatment step and the step of exposing to the stabilizer are performed simultaneously. 18. The method of claim 15, wherein the heat treated low density mat is exposed to the stabilizer after the low density mat has been further compressed into foil. 19. The method according to claim 19, wherein the second heat treatment is performed at a temperature of 600 to 1000 ° C. for 20 seconds.
The method according to claim 11, wherein the heating is performed for 30 minutes. 20. The method according to claim 19, wherein the second heat treatment comprises:
The method according to claim 18, wherein the heating is performed at a temperature of 0 to 1000 ° C. for 20 seconds to 30 minutes. 21. The method according to claim 11, wherein said heat treatment step and said step of exposing to said stabilizer are applied to said compacted graphite particles after forming a foil. 22. The method according to claim 15, wherein the raw graphite particles have an ash content of less than 1%. 23. The raw graphite particles having at least 60
0 ° C. for 30 minutes depending on the heat treatment temperature selected
Heat-treating graphite particles for 5 seconds for a certain period of time; H ₂ , Cl ₂ , B
_{r 2, F 2, HCl,} HNO 3 -HCl and H ₃ PO
₄ is exposed to a stabilizer selected from the group consisting of: the elemental bromine, fluorine and phosphorus concentrations in the graphite structure are 600 ppm and 150 pp, respectively.
m, and a step of selecting the chemical concentrations of Br ₂ , F _2, and H ₃ PO _{4 so} as to be 600 ppm or less, and impregnating the graphite particles that have undergone the heat treatment step and the step of exposing to the stabilizer with an impregnating agent. A step of exfoliating the impregnated graphite particles to a specific volume exceeding 100 cm ³ / g; a step of compressing the exfoliated graphite particles into a flexible graphite structure to form a flexible graphite structure; and 600 applying the flexible graphite structure to the flexible graphite structure. ℃ ~ 1000 ℃
And performing a second heat treatment for a certain period of time. 2. A method for producing a stable, non-bulging, flexible graphite foil structure. 24. A step of heat-treating the raw graphite flake particles at a temperature of at least 600 ° C. for a predetermined time of 30 minutes to 5 seconds according to the heat treatment temperature; a step of impregnating the graphite flake particles with an impregnating agent; The graphite flakes before, during, or after contact with the impregnating agent,
_{H 2, Cl 2, Br 2} , F 2, HCl, HNO 3 -HC
a step of exposing the stabilizing agent selected from the group consisting of l and H ₃ PO _4, the particles of the impregnated graphite flake 100 cm ³ / g
Exfoliating the graphite particles into a flexible graphite structure, and heating the flexible graphite structure at a temperature of 600 ° C. to 1000 ° C. for 30 minutes to 20 minutes depending on the heat treatment temperature. A method for producing a stable, non-bulging, flexible graphite foil structure, comprising: 25. The raw graphite flake particles having an ash content of less than 5%.
4. The method according to 4. 26. An exfoliated graphite particle compact material having a density of 1121 kg / m ³ or more and a crystal structure containing a hydrophobic functional group of a chemical chemically bonded to the surface thereof, wherein the chemical comprises: Hydrogen, hydrogen chloride, chlorine, bromine,
Elemental bromine, fluorine and phosphorus contained in the graphite foil structure are selected from the group consisting of fluorine, phosphoric acid and hydrochloric acid-nitric acid at 600 ppm and 1 ppm, respectively.
A flexible graphite foil structure which does not cause blistering, characterized in that it is contained at a concentration limited to 50 ppm and 600 ppm or less. 27. a step of impregnating graphite particles with an impregnating agent; a step of exfoliating the impregnated graphite particles to a specific volume of more than 100 cm ³ / g; a step of a predetermined time heat treatment for 30 minutes to 5 seconds, depending on temperature, heat-treated, the exfoliated graphite particles, H _2, C
exposed to a stabilizer selected from the group consisting of l ₂ , Br ₂ , and F _2, but having an elemental bromine, fluorine and phosphorus concentration in the graphite structure of 6
Selecting a chemical concentration of Br ₂ , F ₂ and phosphoric acid so as to be 00 ppm, 150 ppm, and 600 ppm or less, and compressing the exfoliated graphite particles into foil. A method for producing a flexible graphite foil structure which does not cause swelling. 28. impregnating graphite particles with an impregnating agent; exfoliating the impregnated graphite particles to a specific volume exceeding 100 cm ³ / g; heat treating said exfoliated graphite particles at a temperature of at least 600 ° C. Heat-treating for 30 minutes to 5 seconds for a certain period of time depending on the temperature;
O ₃ is exposed from the group consisting of consisting -HCl and H ₃ PO ₄ in the selected stabilizer, comprising elemental bromine graphite structure, fluorine and phosphorus concentrations respectively 600ppm, 150 ppm, and 600ppm or less Selecting the chemical concentrations of Br ₂ , F ₂ and phosphoric acid as described above, compressing the exfoliated graphite particles into foil, and performing a second heat treatment on the graphite foil structure at a temperature exceeding 600 ° C. A method for producing a stable, non-bulging, flexible graphite foil structure. 29. The method according to claim 29, wherein the second heat treatment comprises:
The method according to claim 28, characterized by heating at a temperature of 0 to 1000C for 20 seconds to 30 minutes.