Method of producing carbon material

Abstract

To provide heat generating paint that can contribute to reducing CO2, can be produced from a plant feedstock as a carbon source, and can maintain its strength in a wide variety of temperature zones.SOLUTION: The heat generating paint is characterized in that a carbon material produced from a plant feedstock containing 5% or more of a silicon component and including 1 to 50 wt% of a silicon component, is used as a pigment. It becomes possible to feed not only a high voltage DC power but also a high voltage AC power by using a mixture of a carbonized product 19 including many functional groups with graphene 113 as a pigment for paint, while stabilizing the strength thereof.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for producing carbon materials such as graphene from plant-based raw materials.

Background Art

[0002] Conventionally, plant-based raw materials have been used for battery materials, conductive materials, heating elements, tires, building materials, etc. from the perspective of carbon neutrality. In particular, carbon materials with a large specific surface area have been used as materials for batteries, capacitors, etc. due to their large specific surface area. In addition, many carbon materials with excellent electrical conductivity have also been widely used as heating materials and shielding materials.

[0003] For example, Patent Document 1 discloses a method for producing a carbon material, which comprises surrounding a reaction system (a composition containing a carbonaceous raw material and an alkali metal compound) with a carbon-based powder layer when activating the carbonaceous raw material with an alkali metal compound to obtain activated carbon or activated carbon fibers having a high specific surface area, and further containing an inorganic compound layer in the carbon-based powder layer and activating it as necessary. In addition, a method for producing a carbon material in which the yield of the carbon material per container is increased by setting the heating rate during activation to 20 ° C / hr or less. An electric double layer capacitor using the activated carbon or activated carbon fibers obtained by the production method as an electrode material.

[0004] For example, Patent Document 2 discloses an invention comprising a pretreatment step (S1) of drying a plant-based raw material, drying and pulverizing it to obtain a carbon source, a carbonization step (S2) of carbonizing the carbon source to obtain a carbide, and a purification step (S3) of removing impurities containing silica from the carbide obtained in the carbonization step, wherein the carbonization step includes a heating step of supplying an inert gas into a chamber and heating the carbon source in the chamber in a plasma atmosphere.

Prior Art Documents

Patent Documents

[0005] ​

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] In the method of producing a carbon material from a plant-based raw material as in the patent document, activation is performed by using various chemicals and the like, and a porous carbon material is produced. However, although chemicals such as strong alkalis are used, there is a problem that metal corrosion is severe during the firing process such as carbonization, shortening the life of the apparatus. In addition, a production method that can reduce the production cost by minimizing the production process as much as possible has been desired. Further, when used for battery materials or the like, it is necessary to remove silicon to improve the specific surface area and increase the purity of the carbon material. Furthermore, when used in mixture with other materials, it is necessary to improve the dispersibility, and a material having a small specific surface area and a lower silicon ratio than rice husk is preferred.

[0007] The present invention has been made to solve the above problems, and it is an object of the present invention to provide a production method that can contribute to CO2 reduction by using a carbon material produced from a plant-based raw material and can reduce production costs and the like.

Means for Solving the Problems

[0008] Using wheat and barley husks, shochu husks, beer husks, cocoa husks or sake lees as plant-based raw materials, the specific surface area of the carbon material burned at a temperature of 1000 ° C to 1500 ° C in an oxygen-free state is 15 m 2 / g to 80 m 2 / g, and the resistance value measured in a powder state is 1.0×10 -3 Ω·cm to 5×10 -2 Ω·cm.

Effects of the Invention

[0009] Due to the above characteristics, the present invention can contribute to CO2 reduction by using a carbon material with relatively less silicon among carbon materials manufactured from plant-based raw materials, and can provide a carbon material with high dispersibility and purity.

Brief Description of the Drawings

[0010]

Figure 1

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Modes for Carrying Out the Invention

[0011] The heat - generating paint according to the present invention will be described in detail with reference to the drawings. It should be noted that the embodiments and drawings described below are examples of a part of the embodiments of the present invention, and are not used for the purpose of limiting to these configurations, and can be appropriately changed without departing from the gist of the present invention.

[0012] <Biomass material> The plant - based raw material 9 for producing graphene will be described. The present invention produces graphene, which is the final product, using food residues and discarded plant - based raw materials 9. The plant - based raw material 9 uses plants, wood, etc., and in particular, if the discarded plant - based raw materials 9 such as residues when harvesting plants are used as raw materials for producing graphene, raw materials can be obtained at low cost.

Table 1

[0013] Table 1 is a component table of the plant - based raw material 9. Table 1 shows the percentage of the components constituting the raw material shown on the far left to the right below. For example, rice straw has carbon (C) of 37.4%, nitrogen (N) of 0.53%, phosphorus (P) of 0.06%, phosphoric acid (P2O5) of 0.14%, potassium (K) of 1.75%, potash (K2O) of 2.11%, calcium (Ca) of 0.05%, magnesium (Mg) of 0.19% and sodium (Na) of 0.11%.

[0014] Here, the plant-derived silicon-containing porous plant raw material 9 undergoes no substantial change even when carbonized at a low temperature (300 °C or higher and 1000 °C or lower), and the pore arrangement can be maintained by removing silicon. Many of the plant raw materials 9 have a structure in which cells are regularly arranged along the axis, and silicic acid is deposited and thickened on the cell walls. And there are compressed narrow cell rows between the silicified cell rows, and it is possible to obtain a carbon material having a high specific surface area by removing silicon and the like after carbonization. As described above, those containing 13% or more and 35% or less of silicic acid are suitable. If there is too much silicic acid, the resulting graphene will be reduced, so a plant raw material 9 in the range of about 20% is good.

[0015] Examples of the plant raw material 9 rich in carbon are shown in Table 1. In addition to rice straw, there are wheat straw, barley straw, wheat husk, barley husk, cocoa husk, cocoa pod, rice bran, rice husk, buckwheat straw, soybean vine, sweet potato vine, turnip leaf, carrot leaf, corn stalk, sugarcane top, sake lees, coconut husk, coconut meal, peanut shell, orange peel, coffee husk, coffee grounds, shochu lees, beer lees, sawdust of red cedar, bark of Japanese red pine, and fallen leaves of ginkgo. In addition, the plant itself rather than the residue may be used.

[0016] For example, bamboo is composed of cellulose, hemicellulose, and lignin, and minerals are composed of iron, magnesium, calcium, manganese, copper, nickel, etc. Also, when the bamboo leaves are fired, silanol groups (Si-OH) are extracted and extracted as SiO4 in the firing process.

[0017]

Table 2

Table 3

[0018] Tables 2 and 3 are the composition tables of the vegetable raw material 9 that is most suitable for the method of manufacturing a carbon material among the vegetable raw materials 9 in Table 1 described above in the present invention. Table 2 shows the ratios of the components constituting the raw material as percentages. For example, the moisture is 8% - 10%, the ash is 10% - 18%, the lipid is 0.1% - 0.5%, the lignin is 18% - 25%, the hemicellulose is 16% - 20%, the cellulose is 30% - 35%, and the others are 5% - 10%. Thus, the main components that become silica ash 19 are lignin, hemicellulose, and cellulose.

[0019] Table 3 shows the inorganic chemical components of the vegetable raw material 9 shown in Table 2. The vegetable raw material 9 shown in Table 2 contains 80 wt% of organic substances such as cellulose and 20 wt% of inorganic substances. The inorganic chemical components in Table 3 are 92.14 wt% of SiO2, 0.04 wt% of Al2O3, 0.48 wt% of CaO, 0.03 wt% of Fe2O3, 3.2 wt% of K2O, 0.16 wt% of MgO, 0.18 wt% of MnO, and 0.09 wt% of Na2O. The vegetable raw material 9 shown in Table 2 contains a large amount of silicon oxide (SiO2) in the inorganic substances.

[0020] (Example) <Process Flow 1> Referring to FIGS. 6 and 7, the manufacturing process of the method for manufacturing graphene 113 and carbide 19 will be described. FIG. 7 is a diagram showing a process flow indicating the manufacturing process of the embodiment. First, in the pretreatment step S1, after drying the vegetable raw material 9 as described above, the vegetable raw material 9 is pulverized, and the pulverized vegetable raw material 9 and a granulating agent such as PVA are mixed with water at a ratio of 10 to 1, kneaded to make the vegetable raw material 9 into an appropriate size, and heated to near 100 °C on a drying device such as a hot plate to evaporate the moisture to generate the vegetable raw material 9. Here, examples of the pulverizing method include a mill, a mixer, a grinder, etc. In particular, the granulating agent can prevent bumping due to the vapor of the vegetable raw material 9 during induction heating.

[0021] Next, the carbonization process S2 will be described. In the pretreatment process S1, about 0.8 g of the plant-based raw material 9 is placed in the crucible 5 and covered with a metal net or the like. The crucible 5 is placed at a predetermined heating position of the plasma device 10 described above. The pressure in the chamber 1 is reduced to 80 Pa by the vacuum pump 30, and the inert gas 6 is injected into the chamber 1 at a flow rate of 8 to 10 ml / min, and the pressure in the chamber 1 is maintained at a pressure of 1300 to 1500 Pa. Incidentally, in the carbonization process S2, the same graphene can be produced even when Example 1 and Example 3 are used.

[0022] The largest yield of 36% was measured at 500 °C to 800 °C, and a relatively large yield was obtained at 300 °C or higher and 1000 °C or lower. In this measurement, rice straw, bran, coconut shell, rice husk, peanut shell, etc. were used, and the same results were obtained. In the carbonization process S2, the plant-based raw material 9 is carbonized in about 10 to 30 minutes by heating in a temperature range of 300 °C to 1000 °C by thermal plasma by arc discharge while the inert gas 6 flows in.

[0023] Next, the activation process S3 will be described. The carbide 19 obtained above is mixed with potassium hydroxide in a weight ratio of 5 to 1, placed in a small crucible and covered with a lid. The small crucible is also placed in a large crucible and surrounded by activated carbon. Activated carbon is buried to prevent oxygen from entering the small crucible. The heating furnace is heated to a temperature close to 950 °C and fired for about 2 to 3 hours.

[0024] Here, potassium hydroxide is used from the perspective of improving the yield of graphene 113, which is the final product, in order to promote the removal of silicon. Examples of bases include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, alkali metal oxides such as sodium oxide and potassium oxide, alkaline earth metal oxides such as magnesium oxide and calcium oxide, alkali metal sulfides such as sodium sulfide and potassium sulfide, and alkaline earth metal sulfides such as magnesium sulfide and calcium sulfide. In addition, lignin that could not be completely carbonized can also be removed by an acid selected from one or more acids consisting of hydrochloric acid, sulfuric acid, PTSA, and aluminum chloride.

[0025] Among the carbides 19 reacted with potassium hydroxide, silicic acid reacts with potassium hydroxide to form potassium silicate, which is water-soluble. The remaining potassium hydroxide (KOH) and potassium silicate are dissolved in water, and this mixture is filtered through a filter paper set and passed through a vacuum or reduced-pressure filter to remove silicon oxide (silicon). Then, in the drying activation step S3, it was possible to produce graphene 113, which is the final product, with a weight of about 1 / 8 to 1 / 10 compared to when the initial plant-based raw material 9 was granulated.

[0026] The plasma device 10 of this example will be described with reference to FIG. 6. FIG. 6 is a schematic diagram showing the configuration of the plasma device 10 of this example. The plasma device 10 mainly consists of an inert gas 6, a control device 20, a chamber 1, and a vacuum pump 30.

[0027] The inert gas 6 stored in the gas cylinder mainly uses argon, and other examples include helium, neon, nitrogen, etc. The inert gas 6 can be filled into the chamber 1 through the introduction pipe 7 via the gas flow control device 21. The gas flow control device 21 can adjust the flow rate of the inert gas 6.

[0028] Chamber 1 is connected to control valve 22, and the inside of Chamber 1 can be depressurized to a vacuum state by vacuum pump 30. It is connected to Chamber 1 and introduces inert gas 6 into Chamber 1. Between control valve 22 and Chamber 1, leak valve 23 for releasing the vacuum state inside Chamber 1 to atmospheric pressure is provided. Also, between the outlet pipe 8 for introducing air inside Chamber 1 and vacuum pump 30, control valve 14 and leak valve 15 for releasing the vacuum state inside Chamber 1 to atmospheric pressure are provided.

[0029] Also, temperature control device 24 controls high-frequency power supply 4 and manages the temperature maintenance and holding time inside Chamber 1, etc. Plasma device 10 of this embodiment is a method of flowing argon gas, which is inert gas 6, as the working gas under a low pressure close to a vacuum state, flowing a high current between cathode 2 and anode 3 which are between the electrodes, and obtaining thermal plasma by arc discharge. A carbon crucible 5 is installed between this cathode 2 and anode 3, and the crucible 5 contains a plant-based raw material 9 to be described later. The plant-based raw material 9 is carbonized in about 10 to 30 minutes by heating in a temperature range of 300°C to 1000°C by the thermal plasma generated by arc discharge. In addition to the above-described plasma device, there are methods of obtaining thermal plasma by barrier discharge, corona discharge, pulse discharge, and DC discharge type.

[0030] In the above manufacturing method, a gas-phase reaction occurs. Particularly, by mixing a small amount of reactive gas such as inert gas 6, functional groups such as -OH (hydroxyl group), -CHO, -C=O (carbonyl group), -COOH (carboxyl group) are generated, and hydrophilicity is imparted. Note that the manufacturing method is not limited to the above. Also, the heat source may be induction heating, gas, or an electric furnace in addition to the plasma device.

[0031] In the case of induction heating, even if there are insulators such as silicon dioxide (SiO2) in the plant-based raw material 9, magnetic flux can penetrate and the plant-based raw material 9 can conduct electricity. The plant-based raw material 9 itself is also heated, and the heating is accelerated so that it can be carbonized in a short time.

[0032] In addition, the insulator itself, such as silicon dioxide (SiO2), only needs to be heated from the storage box 205 to penetrate the alternating magnetic flux, and since it is not at the melting temperature, it remains as it is, and many insulators such as silicon dioxide (SiO2) remain.

[0033] <Process Flow 2> FIG. 8 shows the main flow related to the manufacturing method for manufacturing the carbon material 100. In this embodiment, the method for manufacturing the carbon material 100 to be graphitized will be described based on the flow from S11 to S16.

[0034] First, the above-mentioned plant-based raw material 9 is pulverized by a pulverizer, but in order to hold it in the slit, hole, or net-like dehydration container 15 described later and perform the dehydration treatment, a carbon raw material pulverization treatment is performed to pulverize it to such an extent that it does not become too fine powder (S11). The carbon raw material pulverization treatment (S11) may be pulverization to such an extent that the alkaline aqueous solution can easily penetrate in the next step. Note that the step of S11 does not particularly need to be performed first, and a method of performing pulverization at the end may also be acceptable.

[0035] Next, an aqueous solution penetration treatment (S12) is performed in which the pulverized plant-based raw material 9 is reacted with the alkaline aqueous solution 20 at a water temperature of 60 °C or higher for 1 hour to 10 hours. It is most efficient in terms of production to provide a step of reacting for about 4 hours.

[0036] Note that this step (S12) may also be a method of immersing the plant-based raw material 9 in the aqueous solution 20 at room temperature for about one week. In this case, it is also possible to adjust the pH of the aqueous solution 20 and use a weakly alkaline aqueous solution 20 with a pH of around 9.

[0037] The concentration of the alkali in the aqueous solution 20 is set to an aqueous solution 20 with a concentration of 10 to 50% wt, and by reacting the plant-based raw material 9 in this aqueous solution 20, the silica component contained in the plant-based raw material 9 is mainly removed, and the silica component is extracted into the aqueous solution 20.

[0038] This increases the concentration of the organic starting components and raises the carbon ratio of the final carbon material 100. The concentration of the alkaline aqueous solution 20 is preferably 30% wt, and the pH is about 9 to 14. The aqueous solution 20 produced by potassium hydroxide with a pH of 13 is most preferable. The input amount of the plant raw material 9 is preferably in the range of 80% wt to 200% wt with respect to the potassium hydroxide before being dissolved in water.

[0039] As alkaline materials, there are alkalis such as sodium hydroxide, potassium carbonate, potassium hydroxide, and sodium carbonate. The most preferable is to use potassium hydroxide with a pH of 13, which is the same component as potassium contained in the plant raw material 9. Using it is effective for graphitization of the carbon material 100.

[0040] This is a photograph obtained by transmission through a scanning transmission electron microscope when carbonization treatment is performed at 300°C to 500°C without performing alkali treatment. When confirming the element distribution, Al (aluminum) is present in particulate form. Also, K (potassium) exists as large particles.

[0041] Therefore, by removing potassium and aluminum, the purity of carbon is improved, which also leads to an improvement in electrical conductivity. Also, it is optimal for the formation of a porous carbon material. In particular, aluminum is easily soluble in alkali and can be more easily removed by carbonization at a high temperature. Also, potassium is easily soluble in alkali, and it is better to use the same potassium hydroxide.

[0042] Next, the alkaline plant raw material 9 is subjected to a dehydration treatment (S13) to remove the moisture of the aqueous solution 20, leaving an alkaline atmosphere without performing a neutralization treatment or washing with water (S13). Since moisture can be removed in this step, it is possible to minimize the damage to the container such as the device or crucible due to the alkaline moisture caused by the evaporation of moisture during carbonization.

[0043] The dehydration process (S13) involves placing the plant-based raw material 9 that has undergone the aqueous solution penetration treatment (S12) into a dehydration container 15 made of metal, cloth, or plastic with a structure provided with any one or a combination of meshes, slits, and holes, and subjecting it to dehydration by centrifugation in a dehydrator like a washing machine. The dehydration container 15 may be any container that allows water to escape by centrifugation, and may particularly be in the form of a bag, box, cylinder, etc.

[0044] As another method of dehydration, it may also be a method of putting the plant-based raw material 9 into a bag-shaped dehydration container 15 and squeezing the bag with a wringer to remove water.

[0045] Centrifugal dehydration is performed (S13) using a rotary dehydration device typified by a washing machine. The rotation speed during dehydration is preferably from 300 to 3000 rpm, and most preferably from 500 rpm to 1500 rpm. This centrifugation can promote the destruction of plant cells and the excretion of impurities such as silica contained in the plant-based raw material 9.

[0046] Next, a drying process (S14) is similarly performed to remove the water of the aqueous solution 20 by a drying device or air-drying. The state is maintained without performing a neutralization treatment and without rinsing with water, leaving an alkaline atmosphere (S14). Since water can be removed in this step, it is possible to minimize the damage to the device or containers such as crucibles caused by alkaline water due to the evaporation of water during carbonization. Note that since it is only necessary to remove the alkaline water, if water can be removed in the above-mentioned dehydration step (S13), the drying step (S14) is not necessarily required, and it may be in a wet state.

[0047] Next, a carbonization process is performed (S15) to carbonize the plant-based raw material 9 in an alkaline atmosphere while flowing a gas such as nitrogen or argon gas or sealing it with carbon felt, etc., in a state without oxygen, and maintaining a combustion temperature of 1100 °C for 5 hours.

[0048] In the carbonization process (S15), the higher the temperature, the more the graphitization and graphitization progress. The most suitable is around 1000 °C to 2200 °C, and it is sufficient if the above temperature can be maintained for a carbonization time of 2 hours to 10 hours.

[0049] Also, although metals for storing the vegetable raw material 9 are often used in the manufacturing apparatus, in order to withstand alkalinity, a rotary kiln type carbonization apparatus or an induction heating furnace, an electric furnace, etc. that can withstand alkalinity, such as using thermal spraying of alumina or the like or using a storage container for storing the vegetable raw material 9 made of an alumina material, may be used.

[0050] Compared with the step of activating by reacting a solid alkaline material with the vegetable raw material 9 as in the prior art, the vegetable raw material 9 in the state of S13 is less likely to cause direct corrosion of the metal by the alkali, so it is possible to improve the durability of the manufacturing apparatus.

[0051] Finally, the carbon material 100 after the carbonization treatment (S15) is exposed to water or an acidic aqueous solution such as hydrochloric acid, sulfuric acid, and citric acid for neutralization treatment (S16), and further the remaining silica, etc. is removed (S16). Also, after that, if it is dried and vacuum stored, etc., it is possible to ship it while maintaining the physical properties such as the electric conductivity of the carbon material 100.

[0052] For the neutralization treatment (S16), neutralization by washing using only water such as pure water is desirable in order to improve the purity. Neutralization with an acid or the like is also acceptable, but since it is also necessary to wash away the acid and remove solid matter such as silica, the neutralization treatment (S16) using water is the best in terms of cost.

[0053] At that time, as shown in FIG. 9, when pure water 81 is put into the container 80, the carbon material 100 and pure water are put into the permeation membrane 82 that allows only bag-shaped water molecules to pass through, and both ends 83 are submerged in the pure water, the pressure balance works from the aqueous solution containing impurities including the carbon material 100, and the moisture containing the alkaline component flows through the membrane to the pure water 81. In this way, by using the permeation membrane 82, the treatment can be performed quickly.

[0054] Next, referring to FIG. 10, a neutralization process (S16) of another example will be described. An aqueous solution (L1) containing the carbon material 100 is passed through a tube 62 having a plurality of tubular reverse osmosis membranes 67 by pumping it up from a bathtub 64 containing the carbon material 100 and pure water with a pump 61.

[0055] An aqueous solution (L2) containing an alkaline component is recovered from the tube 62 into a recovery container 63, and an aqueous solution (L3) containing the carbon material 100 is returned to the bathtub 64. Pure water in an amount equal to that recovered in the recovery container 63 is replenished into the bathtub 64. In this way, by circulating, the aqueous solution containing an alkaline component is gradually neutralized.

[0056] <Process Flow 3> A method for manufacturing the carbon material 100 using the rice husk among the plant-based raw materials 9 of the present embodiment in the examples will be described with reference to FIG. 11. It is suitable for the method of manufacturing the carbon material 100 used as a conductive material in particular.

[0057] The plant-based raw material 9 is pulverized. Since micronization is performed at the end, in this step, it is sufficient to pulverize to the extent that it can penetrate inside when immersed in water, and since it passes through a dehydration step, it may have a size that does not slip through slits or holes. The size after pulverization is preferably about 5 mm to 10 mm. Here, examples of the pulverization method include a mill, a mixer, a grinder, etc. Also, the pulverization step may not be particularly provided as long as water or the like penetrates into the raw material during washing.

[0058] Next, the pulverized plant-based raw material 9 is washed with water (S22). For example, the rice husk is immersed in pure water. After immersing the rice husk for about 1 hour to 1 day, stones, mud, etc. are washed away. The liquid temperature is preferably from room temperature to 80°C. The water washing (S22) may be performed by stirring with a stirrer after pouring water. Also, washing may be performed by stirring while pouring water little by little. Note that for stirring, a vortex-type device or a device that rotates a blade to stir may be used, or a stirrer device or the like may be used.

[0059] Next, put the washed plant-based raw material 9 into the above-described dehydration container 15, and perform dehydration using a rotary dehydration device typified by a washing machine (S23). The rotation speed during dehydration is preferably from 300 to 3000 rpm, and most preferably from 500 rpm to 1500 rpm.

[0060] Also, the gravitational acceleration during centrifugation by the dehydration device is most preferably about 2G to 5G. The dehydration device may be the same device from washing to rinsing and dehydration (S22 - S23), and the dehydration container 15 may have a structure for storage or attachment.

[0061] By dehydration, impurities are discharged together with the moisture. And it is possible for the plant-based raw material 9 to move to the next firing step in a wet state without going through the drying step as it is. It has been confirmed that the decomposition of the tissue of the plant-based raw material 9 is promoted by this dehydration step by rotation, and it is possible to proceed to the next step without particularly obtaining a drying step.

[0062] Therefore, it has become possible to shorten the manufacturing time by reducing the drying step. Also, during dehydration, when discharging moisture by centrifugation to the outside, the destruction of the cell wall of the plant-based raw material 9 is promoted, and the destruction progresses deeper inside.

[0063] Therefore, in the examples, if rotary dehydration is performed, it is not always necessary to obtain a drying step, but drying further reduces the influence on the combustion device such as rust. Also, compared with the step of activating together with the solid alkaline material, the influence on the combustion device is even less.

[0064] Next, in the firing step (S24), put the plant-based raw material 9 into a furnace, fill the inside of the furnace with an oxygen-free state with argon gas or nitrogen gas, raise the furnace temperature to 1100°C, and maintain a constant temperature at 1100°C for about 1 to 10 hours. Then, the total firing time is set to 1 day by natural firing of the plant-based raw material 9. Thereby, the carbon material 10 is produced.

[0065] Also, in the firing process (S24), since the plant-based raw material 9 after the dehydration process (S23) enters the firing process (S24) while maintaining a somewhat moist state, different from a completely dry state, so-called steam activation occurs in the initial state, leading to the promotion of cell wall destruction and decomposition.

[0066] In addition, the generation of micropores due to steam activation occurs, and it becomes easier to form a porous material similar to activated carbon. In the firing process (S24), it is advisable to use a rotary kiln type carbonization device, an induction heating furnace, an electric furnace, a continuous carbonization furnace, or the like.

[0067] Also, during the water washing (S22), the plant-based raw material 9 is stored in a container such as an autoclave, and pressure is applied from 2 atmospheres to 2.45 atmospheres together with water, and a temperature of 120°C to 128°C is applied. As a result, the cell wall of the plant-based raw material 9 is quickly destroyed, leading to the removal of impurities and the improvement of purity.

[0068] <Process Flow 4> With reference to FIG. 14, a method for manufacturing the carbon material 100 using the rice husk among the plant-based raw materials 9 of the present embodiment in the examples will be described. It is particularly suitable for the method of manufacturing the carbon material 100 used as the conductive material.

[0069] The plant-based raw material 9 is pulverized. Since micronization is performed in the last step, in this step, pulverization to the extent that it penetrates inside during immersion in water is sufficient, and since it goes through a dehydration process, it may have a size that does not slip through slits or holes. The size after pulverization is preferably about 5 mm to 10 mm. Here, examples of the pulverization method include mills, mixers, grinders, etc. Also, particularly, the pulverization step may not be necessary as long as an aqueous solution or the like penetrates the raw material during washing or the like.

[0070] Next, the plant-based raw material 9 is carbonized at a temperature of 500°C to 800°C for about 3 minutes to 3 hours (S32). The carbonized carbide 19 is immersed in an acid (S33). At this time, hydrofluoric acid is suitable, and any solution that dissolves the silicon component in the acid solution may be used.

[0071] Next, after pickling (S33), the carbide 19 is washed with water or the like to remove the silicon component. At this time, it is best to neutralize the carbide by washing with water or the like. Then, it is immersed in an alkaline aqueous solution as in the above-described process flow 1 or 2 (S34).

[0072] Next, the carbide 19 is put into the above-described dehydration container 15, and dehydration is performed using a rotary dehydration device typified by a washing machine (S35). The rotation speed during dehydration is preferably from 300 to 3000 rpm, and most preferably from 500 to 1500 rpm. In terms of gravitational acceleration, about 2G to 5G is good.

[0073] Then, the dehydrated carbide 19 can be transferred to the next firing step in a wet state without going through a drying step as it is. The silicon component contained in the carbide 19 is removed by this dehydration step by rotation (S35).

[0074] Therefore, it has become possible to shorten the manufacturing time by reducing steps such as drying. Also, during dehydration, when water is discharged to the outside by centrifugation, the destruction of the cell wall of the plant raw material 9 is promoted, and the alkaline aqueous solution penetrates deeper inside.

[0075] Therefore, in the examples, if rotary dehydration is performed, it is not always necessary to obtain a drying step, but drying further reduces the influence of rust and the like on the combustion device. Also, compared with the step of activating together with a solid alkaline material, the influence on the combustion device is even less.

[0076] Next, in the firing step (S35), the plant raw material 9 is put into a furnace, the inside of the furnace is filled with argon gas or nitrogen gas in an oxygen-free state, the furnace temperature is raised to 1100 ° C, and after maintaining the temperature at 1100 ° C for a certain time of about 1 to 10 hours, the carbon material 100 is produced.

[0077] Also, in the firing process (S36), since the plant-based raw material 9 after the dehydration process (S35) enters the firing process (S36) while maintaining a somewhat moist state, different from a completely dry state, so-called steam activation occurs in the initial state, leading to the destruction of cell walls and the promotion of the formation of pores in the porous material.

[0078] In addition to steam activation, activation by an alkaline atmosphere also causes the generation of micropores, making it easier to form a porous material similar to activated carbon. In the firing process (S36), it is advisable to use a rotary kiln type carbonization device, an induction heating furnace, an electric furnace, a continuous carbonization furnace, etc. Finally, the neutralization treatment (S16) of Process Flow 2 may be performed.

[0079] <Process Flow 5> After going through the processes of Process Flows 1 to 4 described above, one or more of the raw materials such as wheat or barley husks, cocoa husks, sake lees, shochu lees, and beer lees may be mixed to produce a carbon material.

[0080] As another alternative example, based on Process Flow 3, in an oxygen-free state in the grinding process, it is heated at a temperature of 100°C to 200°C for about 1 to 2 hours to evaporate the moisture, and then a rotary kiln type carbonization device, an induction heating furnace, an electric furnace, a continuous carbonization furnace, etc. are used to burn it at a temperature of 1000°C to 1500°C. Also, wheat or barley husks, cocoa husks, sake lees, shochu lees, and beer lees may be fired after obtaining the processes from S21 to S23.

[0081] Also, based on Process Flow 3 (Figure 11), carbon materials such as wheat or barley husks, cocoa husks, sake lees, shochu lees, and beer lees may be burned after going through the dehydration process (S23) to a certain extent without being completely dried even if they contain moisture from the stage of procuring the raw materials. In this way, even in a moist state, if it contains some moisture, it is more likely to be in a state like steam activation, more likely to become porous, and the decomposition of cells is promoted.

[0082] In particular, sake lees, shochu lees (hulls), and beer lees (hulls) can be burned in a slightly wet state without undergoing a drying process after draining the remaining residue from production through a dehydration process (S23) while still wet, so the working process can be shortened.

[0083] Also, the carbon material 100 that has undergone the dehydration process (S23) promotes the decomposition of the structure and the removal of excess mineral components. Also, there is no negative impact even if it is carbonized through the water washing and rinsing (S22), then the dehydration process (S23), and finally the combustion process ()24).

[0084] The specific surface area of the carbon material 100 obtained by such a manufacturing method was measured using the BET adsorption isotherm based on the nitrogen adsorption amount at liquid nitrogen temperature.

[0085] As a result, wheat and barley husks, cocoa husks, sake lees, shochu lees, and beer lees were 15 m 2 / g to 80 m 2 / g. Wheat and barley husks, shochu lees, and beer lees were 15 m 2 / g to 35 m 2 / g. Sake lees were 40 m 2 / g to 70 m 2 / g. Cocoa husks were 45 m 2 / g to 75 m 2 / g.

[0086] Since the small specific surface area improves the dispersibility in emulsions such as acrylic, the carbon material is uniformly mixed and the conductivity is improved. Also, the improved dispersibility results in better dispersibility of the coating film and enables the securing of strength.

[0087] The electrical conductivity of each carbon material 100 was measured by measuring the resistance value of the powder. Shochu lees and beer lees were 3.0×10 -2 Ω·cm, sake lees were 2.5×10 -2 Ω·cm, cocoa husks were 2.5×10 -2 Ω·cm, and graphene from rice husks was 2.3×10 -2It was Ω·cm. And the powder resistance values of wheat and barley husks, cocoa husks, sake lees, shochu lees, and beer lees are approximately 1 to 5 Ω·cm.

[0088] Also, the purity of wheat and barley husks, shochu lees, and beer lees is such that C (carbon) is 70%wt to 85%wt, Si (silicon) is 3wt% to 15wt%, and the remaining metal impurities are such that Na is 0.7wt% to 1.7wt%, Mg is 0.7wt% to 1.7wt%, P and K are 1.5wt% to 4wt%, and Ca is 0.35wt% to 1.0wt%.

[0089] Furthermore, in order to further improve the purity of these wheat and barley husks, shochu lees, and beer lees, by subjecting them to acid treatment with hydrofluoric acid or the like, C (carbon) was 86%wt to 95%wt and Si (silicon) was 3wt% to 9wt%. The remaining metal impurities were such that K was 0.35wt% to 7wt%.

[0090] (Graphene and Carbides) The carbide 19 obtained in the carbonization step S2 and the firing steps (S24, S32) and the graphene 113 which is the carbon material 100 obtained in the activation step S3, manufactured according to the above example, will be described below.

[0091] Figure 1 is the Raman spectrum of the graphene 113 obtained by the manufacturing apparatus of the present invention. Figure 2 is the Raman spectrum of the carbide 19 obtained by the manufacturing apparatus of the present invention. These figures were analyzed by a Raman spectrometer, and the obtained data is a Raman spectrum with the horizontal axis being the wavelength (wave number (Raman shift (cm-1))) and the vertical axis being the intensity.

[0092] Also, as shown in Table 4, they are the peak value IG of the G band (2850 cm-1) and the peak value ID of the 2D band (1650 cm-1) which are the peaks of the wavelength by the Raman spectrum method.

[0093] And as shown in Table 4, the value obtained by dividing IG by ID for graphene 113 is 1.68, indicating that among the plant-based raw materials 9, the number of layers is small. In particular, carbide 19 contains a large amount of silicon, and it was confirmed that oxygen functional groups such as -OH, -CHO, and -COOH were generated.

[0094] The value obtained by dividing IG by ID for graphene 113 is preferably 0.9 or more and shows a value of about 0.9 to 2.0.

[0095] The ash content of carbide 19 obtained in the carbonization step S2, excluding carbon, is as much as 37.1 wt% according to thermogravimetric measurement, and among the ash, silicon (Si) accounts for 24 wt% to 50 wt% of the entire carbide 19. In addition, K is 0.51 wt% to 7 wt%, Al is 0.1 wt% to 1.6 wt%, Ca is 0.17 wt% to 0.5 wt%, Fe is 0.4 wt%, and Cr, Ni, Mn, Mg, P, S, and Na are 0.1 wt% or less.

[0096] Carbide 19 obtained in the carbonization step S2 without performing the activation step S3, which is a so-called activation treatment, contains a large amount of silicon. When carbonized in an inert gas, it is not strongly reduced and becomes SiO2-x, binds in the form of aromatic -OH groups and -O-Si-O-R, becomes a lignin polysaccharide complex, and is likely to form in the form of C / SiOx.

[0097] In addition, graphene 113 obtained in the activation step S3 described later has an ash content, excluding carbon, of as much as 1% to 24 wt% according to thermogravimetric measurement, and among them, silicon (Si) accounts for 1 wt to 20 wt% of the entire graphene 113. In addition, K is 4.3 wt%, Al is 1.5 wt%, Ca is 1.3 wt%, Fe is 0.4 wt%, and P, Mn, Cl, S, and Mg are 0.1 wt% or less.

[0098] As described above, the silicon content of graphene 113 and carbide 19, which are carbon materials 100, is high, ranging from 1 wt% to 50 wt%.

[0099]

Table 4

[0100] Therefore, it is considered that they are likely to adsorb metal ions and the like. Also, as shown in Table 4, the mesopore volume measured by gas adsorption measurement and water vapor adsorption measurement was 0.487 ml / g for graphene 113 and 0.259 ml / g for carbide 19. Further, the micropore volume was 0.46 ml / g for graphene 113 and 0.27 ml / g for carbide 19.

[0101] Also, as shown in Table 4, the particles of graphene 113 or carbide 19 showed a diameter distribution from 15 μm to 229 μm, and the median diameter, which is the median value of the integrated value of the distribution, was about 110 μm.

[0102] In this way, a mesopore volume of 0.2 ml / g to 0.6 ml / g is formed. In particular, graphene 113 after the activation treatment for removing impurities described later shows a higher value, and it is considered that mesopores and micropores have grown due to the removal of silicon.

[0103] Also, as shown in Table 4, measured by the water vapor adsorption measurement method, the specific surface area according to the BET equation was 1792 m 2 / g for graphene 113, and this range has a range of 890 m 2 / g to 2500 m 2 / g. For carbide 19, it was 726.4 m2 / g, and this range has a range of 890 m 2 / g to 1500 m 2 / g. In both cases, the specific surface area is large, and graphene 113 after removing the silicon component (Si) has a larger specific surface area.

[0104] Therefore, the graphene 113 has a high adsorption effect. In particular, the carbon material 100 produced from rice husks using the plant-based raw material 9 in the process flow 4 was from 2000 m 2 / g to 2600 m 2 / g value.

[0105] In addition, the carbide 19 has a state in which the element component Si (silicon) is contained in a minute state on the surface and inside of the carbide 19 in the state of Si (silicon) or silicon dioxide (SiO2), and a state in which it is aggregated and formed on the surface and inside of the carbide 19 in the state of Si (silicon) or silicon dioxide (SiO2). And when the carbide 19 is subjected to an activation treatment, the purity of carbon increases and at the same time the specific surface area improves.

[0106] As shown in Table 4, the true density measured by the gas displacement density measuring device was 2.56 g / cm3 for the graphene 113 and 2.27 g / cm3 for the carbide 19. Also, the bulk density of the graphene 113 was from 0.21 to 0.29 g / cm3.

[0107] Also, the powder resistance value measured by the double ring method and the four-terminal method was 1.27×103 to 5 Ω·cm for the carbide 19, and by removing silicon, the graphene 113 became 1.0×10-2 Ω·cm and its conductivity improved. Note that the lower the resistance value, the better, but for the graphene 113, 1.0×10-3 Ω·cm to 3.8×10-2 Ω·cm is optimal. In addition, when the carbide 19 leaves a large amount of silicon, it becomes easier to dissolve in substances that are easily adsorbed by silicon, and at the same time the insulation performance improves.

[0108] (Heat-generating paint) Below, the heat-generating paint produced using the above-described carbon material 100 (carbide 19 and graphene 113) as a pigment will be described. The applicant has conducted tests on various types of paints and found the optimal conditions. As the types of paints raised in this example, tests of a solvent two-component type, a solvent one-component type, and an aqueous one-component type were conducted.

Table 5

[0109] As shown in Table 5, the solvent two-component type uses an acrylic urethane as the binder, dilutes it with xylene as the solvent, and uses the carbon material 100 (carbide 19 and graphene 113) described above as the pigment. This solvent two-component type is a type of paint that is cured using a curing agent.

[0110] The solvent one-component type uses silicone as the binder, uses xylene as the solvent, and uses the carbon material 100 (carbide 19 and graphene 113) described above as the pigment. This solvent one-component type is a type that cures by heat and has a heat resistance of 150 °C and is excellent in heat resistance.

[0111] The water-based one-component type uses an acrylic emulsion as the binder, uses water as the solvent, and uses the carbon material 100 (carbide 19 and graphene 113) described above as the pigment. Also, while stirring the carbon material with a disper, the binder was gradually added, and the addition amount at which the stirred liquid remained liquid was determined as the limit amount. Also, the pigment weight concentration (PWC value) at that time was calculated.

[0112]

Table 6

[0113] Also, the film-forming property is the result of a test to see if the coating film peels off when the surface of the coating film is scratched with a nail or the like. In the case of ○, there is no peeling, and × indicates that there is peeling. Also, the gloss is the result of measuring the 60-degree gloss value. <1 indicates that it is less than 1.

[0114] Furthermore, the film property is the result of a test to see if the coating film on the surface is scratched with a fingernail or the like and the coating film does not peel off. In the case of ○, there is no peeling, and × indicates that there is peeling.

[0115] Flexibility was evaluated by forming a coating film on paper and bending the paper into a mountain fold to see if cracks or fissures occurred in the coating film at the peak part. In the case of ○, there are no cracks or fissures, and × indicates that cracks or fissures have occurred.

[0116] Next, the performance as a heat-generating paint will be described. FIG. 3 is a diagram in which the above-described solvent single-component type heat-generating paint 50 is applied to an insulator 51 such as paper, cloth, or plastic resin. + Electrode 52 and - electrode 53 are provided at the central end of the heat-generating paint 50, and heat is generated from the portion where the heat-generating paint 50 is applied by supplying power to the electrodes. The distance H between the electrodes is 4.5 cm, and the area where the paint is applied is 22.5 cm2.

[0117] Also, FIGS. 4 and 5 are diagrams showing the heat-generating characteristics of the heat-generating paint 50. FIG. 4 is a graph of time (seconds) and temperature (°C) of a heating element 40 with a coating film thickness of 160 μm to 175 μm. V1 is the temperature graph measured at point P in FIG. 3 when DC20V is supplied. The power value is from 4 to 4.8 W, and the temperature rises from room temperature 22.1°C to about 62°C in about 300 seconds.

[0118] V2 is the temperature graph measured at point P in FIG. 3 when DC12V is supplied. The power value is from 2 to 2.4 W, and the temperature rises from room temperature 26.3°C to about 43.4°C in about 300 seconds.

[0119] Figure 5 is a graph showing the time (seconds) and temperature (°C) of the heating element 40 with a coating film thickness of 60 μm to 75 μm. V1 is the temperature graph measured at point P in Fig. 3 when DC20V is supplied. The power value is from 1.6W to 2.0W, and the temperature rises from room temperature of 25.4 °C to about 44.1 °C in about 280 seconds.

[0120] V2 is the temperature graph measured at point P in Fig. 3 when DC12V is supplied. The power value is 0.6W, and the temperature rises from room temperature of 25.4 °C to about 32.6 °C in about 240 seconds.

[0121] Since the carbon material 100 contains a large amount of silicon, it is not necessary to add an inorganic material later, and it is possible to improve the strength and electric resistance performance of the paint. In particular, a heating paint containing silicon in the carbon material can maintain the continuity of the paint film even when heated to a high temperature, and a planar heater with high heat resistance can be produced.

[0122] Also, by mixing the carbide 19 containing a large number of functional groups with the graphene 113 to form a pigment of the paint, it is possible to supply high-voltage power such as alternating current as well as direct current while stabilizing the strength.

[0123] Also, in adjusting the resistance value, the carbide 19 containing a large number of functional groups makes dispersion and mixing easier. The mixing ratio is preferably such that the ratio of the carbide 19 to the graphene 113 is about 0.5:9.5 to 3:7. Also, the carbon material 100 with a powder resistance in the range of 1.0×10 -3 Ω·cm to 3.8×10 -2 Ω·cm can be used alone or in combination with the carbon material 100.

[0124] Next, FIGS. 12 and 13 show another example of the heating element 40. Fig. 12(A) is a front view of the heating element 40. Fig. 12(B) is a cross-sectional view of the heating element 40 cut along line A - B in the front view.

[0125] The heat - generating paint 50 was prepared by kneading a carbon material 100 into a synthetic resin emulsion typified by vinyl chloride - based, vinyl acetate - based, acrylic - based, etc. in a ratio of 10% wt to 75% wt and then making it into a paint. The best ratio was that the carbon ratio was 20% wt to 60% wt. Also, it may be dispersed using water.

[0126] The thickness t of the paint film was formed to be from 500 μm to 1000 μm. The ideal thickness of the paint film is from 100 μm to 1500 μm and can be appropriately changed according to the resistance value and the place of use. When an acrylic - based emulsion was used, thick coating was possible.

[0127] The heating element 40 shown in FIG. 12 was formed with a + electrode 52 and a - electrode 53 on a wiring 41 using a copper foil, a silver foil, a paste of copper or silver, etc., or a conductive wire on a base material 42. The base material 42 may be glass, pottery, concrete, cement, cloth (glass fiber, cotton yarn, polyester), plastic, etc. The heat - generating paint 50 was applied and dried on the base material and the electrodes.

[0128] The heating element 40 was formed with a total length of 56 cm, a width of 4 cm, and an electrode width of 1 cm, and the overall resistance between the electrodes was from 1 Ω to 20 Ω. When DC12V was applied, a temperature rise from room temperature to 20 °C to 80 °C was confirmed at around 24W of power. Here, the carbon material 100 most suitable for the heat - generating paint was the condition where plant - based raw materials 9 such as cocoa shells, barley husks, and wheat husks were burned at a combustion temperature of 900 °C to 1500 °C.

[0129] The heating element 40 shown in FIG. 13 was formed with a + electrode and a - electrode on a wiring 41 using a copper foil, a silver foil, an aluminum foil, a paste of copper or silver, etc., or a conductive wire on a base material 42. The base material 42 may be glass, pottery, concrete, cement, cloth (glass fiber, cotton yarn, polyester), aluminum tape, plastic, etc.

[0130] The non-woven fabric 43 was laid on the base material 42 and the wiring 41, and the heat-generating paint 50 was applied thereon and dried. The non-woven fabric 43 was of a thinness that allowed transparency and was made of a material through which the heat-generating paint 50 could pass. The thickness of the non-woven fabric 43 was from 10 g / m 2 to 30 g / m 2 was good.

[0131] For the non-woven fabric 43, various materials such as polyester, polypropylene, polyethylene, rayon, nylon, and wool can be used. Since the heat-generating paint 50 can pass through the part of the non-woven fabric 43, when viewed from the cross-section, the non-woven fabric 43 and the heat-generating paint are mixed.

[0132] The heating element 40 was formed with a total length of 50 cm, a width of 4 cm, and an electrode width of 1 cm, and the overall resistance between the electrodes was from 1 Ω to 20 Ω. When DC 12V was applied, a temperature rise from room temperature to 20 °C to 90 °C was confirmed at around 24W of power.

[0133] Here, the carbon material 100 most suitable for the heat-generating paint was under the condition that the plant-based raw materials 9 such as cocoa shells, barley husks, wheat husks, shochu lees, and beer lees among the plant-based raw materials 9 were burned at a combustion temperature of 900 °C to 1500 °C.

[0134] Alternatively, the heat-generating paint 50 may also be a paint in which the carbon material 100 is mixed into an aqueous solution obtained by diluting sodium silicate with water. It is particularly optimal for the carbon material 100 obtained by carbonizing the plant-based raw materials 9 containing 5% to 15% of silicon. The silicon contained in the carbon material 100 dissolves into sodium silicate, improving conductivity and strength. Also, since it is optimal as a refractory paint, it is possible to reduce the risk of ignition as a heat-generating paint.

[0135] (Technical Features) An example of the technical feature points of the present embodiment is shown in parentheses below, but it is not particularly limited and is illustrative, and the effects considered from these features are also described.

[0136] <Feature Point 1> Using wheat, barley husks, shochu husks, beer husks, cocoa husks, or sake lees as plant-based raw materials, and burning them at a temperature of 1000°C to 1500°C in an oxygen-free state, the specific surface area of the carbon material is 15 m 2 / g to 80 m 2 / g, and the resistance value measured in powder form is 1.0×10 -3 Ω·cm to 5×10 -2 Ω·cm.

[0137] By using a carbon material with relatively little silicon among the carbon materials produced from plant-based raw materials, it is possible to contribute to CO2 reduction and provide a carbon material with high dispersibility and purity.

[0138] <Feature Point 2> It is characterized by including a cleaning step of immersing the plant-based raw materials in an aqueous solution, stirring, and washing with water, a dehydration step of storing the plant-based raw materials in a container after the cleaning step, rotating them with a rotary dehydration device, and dehydrating the moisture contained in the plant-based raw materials, and a firing step of firing the plant-based raw materials after the previous dehydration step.

[0139] The aqueous solution may be an alkaline aqueous solution, pure water, treated water, or tap water. Also, the liquid temperature of the aqueous solution is preferably from normal temperature (20°C) to 100°C. Also, the dehydration container and the container for washing may be the same container. Also, the cleaning step and the dehydration step may be a device of a type that performs them with the same device like a washing machine.

[0140] Due to the above characteristics, when immersed in a solution as in the prior art or when drying during water washing, the time is shortened, so the production efficiency is improved, and at the same time, the decomposition of cellulose and the like is promoted, and the removal of impurities is also possible.

Industrial Applicability

[0141] Regarding the industrial use of the carbon material of the present invention, in addition to the heat-generating paint for construction such as concrete, it can be used as a conductive paint for battery materials, circuit boards, heat dissipation materials, etc.

Explanation of Symbols

[0142] 1 chamber 2 cathode 3 anode 4 high-frequency power supply 5 crucible 6 inert gas 7 inlet pipe 8 outlet pipe 9 plant-based raw material 10 plasma device 14 control valve 15 leak valve 19 carbide 20 control device 21 gas flow control device 30 vacuum pump 40 heating element 42 substrate 50 heating paint 51 insulator 52, 53 electrodes 100 carbon material 113 graphene S1 pretreatment process S2 carbonization process S3 activation process.

Claims

1. Using wheat, barley husks, shochu husks, beer husks, cocoa husks, or sake lees as vegetable raw materials, the specific surface area of the carbon material burned at a temperature of 1000 °C to 1500 °C in an oxygen-free state is 15 m ２ / g to 80 m ２ / g, and the resistance value measured in a powder state is 1.0 × 10 －３ Ω·cm to 5 × 10 －２ Ω·cm. A method for producing a carbon material, characterized by having such a resistance value.

2. The purity of the carbon material is such that C (carbon) is 70% wt to 85% wt, Si (silicon) is 3 wt% to 15 wt%, and the remaining metal impurities are such that Na is 0.7 wt% to 1.7 wt%, Mg is 0.7 wt% to 1.7 wt%, P and K are 1.5 wt% to 4 wt%, and Ca is 0.35 wt% to 1.0 wt%. The manufacturing method of the carbon material according to Claim 1, characterized by this.

3. A washing step of immersing the plant-based raw material in an aqueous solution and stirring for washing, After the washing step, the plant-based raw material is stored in a container and rotated by a rotary dehydration device to dehydrate the moisture contained in the plant-based raw material, a dehydration step, A firing step of firing the plant-based raw material in a wet state without drying after the previous dehydration step, The manufacturing method of the carbon material according to Claim 1, characterized by including these.

4. The manufacturing method of the carbon material according to Claim 1, characterized in that the rotational speed of the rotating dehydration device is 300 rpm to 3000 rpm.

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