Manufacturing method of heat-generating paint

Abstract

To provide a heat-generating paint that can be manufactured using carbon materials produced from vegetable materials as a carbon source to reduce CO2 emissions, and a heat-generating paint that can maintain strength even in various temperature ranges.SOLUTION: A heat-generating paint comprises as a pigment a carbon material containing 1 wt.% to 50 wt.% of a silicon component produced from a vegetable material whose silicon component content is 5% or more. It is also possible to supply high voltage power such as alternating current as well as direct current while stabilizing the strength by mixing graphene 113 with carbide 19 comprising many functional groups and using the mixture as a pigment for the paint.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a heat-generating paint for use in heat-generating and conductive applications, manufactured using graphene or carbon materials produced from plant-based raw materials as a carbon source. [Background technology]

[0002] Heating elements have been used in various fields for a long time. For example, they are used as heat sources in hot presses, pipe heaters, heat seal and laminating equipment, drying equipment, de-fogging equipment, snow melting equipment, and photocopiers. Furthermore, a major advantage of using paint to coat the heating element is that it can be installed regardless of its shape. Also, from a cost perspective, coating it allows for application only to the desired area or location, resulting in significant cost savings.

[0003] Thus, various inventions have been proposed for heat-generating paints, which offer significant advantages. For example, Patent Document 1 describes a heating sheet comprising a heating layer with a thickness of 10 to 150 μm formed on a support, and a plurality of electrodes connected to the heating layer at a distance from each other, wherein the parts of the electrodes other than those connected to an external circuit are sealed with an insulating coating, and the overall maximum thickness is 500 μm or less. The heating layer of this sheet is formed by applying an aqueous composition containing a conductive material onto a resin support that has undergone corona discharge treatment.

[0004] For example, Patent Document 2 describes an invention of a heat-generating paint that has high heat generation even at low voltage and can form a paint film with few disconnections that can maintain the paint film even in high temperature ranges, and the invention is mainly composed of a fine carbon material and an inorganic binder. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-163540 [Patent Document 2] Japanese Patent Publication No. 2020-26458 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0006] As shown in Patent Document 2, it is composed of an inorganic binder and fine carbon material. A problem with this is that many of these are manufactured from ore and do not contribute to CO2 reduction. Furthermore, it is necessary to improve the strength against breakage and other issues by uniformly dispersing dissimilar materials, such as carbon and inorganic materials, into a paint. Therefore, if the proportion of carbon material is too high in order to lower the resistance, it becomes difficult to increase the strength of the heat-generating paint.

[0007] The present invention was made to solve the above problems, and aims to provide a heat-generating paint that can contribute to CO2 reduction by using a carbon material manufactured using plant-based raw materials as a carbon source, and that can maintain its strength even in a wide range of temperatures. [Means for solving the problem]

[0008] This product is characterized by using a carbon material containing 1 wt% to 50 wt% silicon, manufactured from plant-derived raw materials containing 5% or more silicon, as a pigment. [Effects of the Invention]

[0009] Based on the above features, the present invention can contribute to CO2 reduction by using a carbon material manufactured using plant-based raw materials as a carbon source, and can provide a heat-generating paint that maintains its strength even in various temperature ranges. [Brief explanation of the drawing]

[0010] [Figure 1] This is the Raman spectrum of graphene in the embodiment. [Figure 2]It is the Raman spectrum of the carbide of the embodiment. [Figure 3] It is a schematic diagram showing the configuration of a heating element with the heat - generating paint of the embodiment applied under the coating film. [Figure 4] It is a schematic diagram showing the temperature characteristics of the heating element of the embodiment. [Figure 5] It is a schematic diagram showing the temperature characteristics of the heating element of the embodiment. [Figure 6] It is a schematic diagram showing the configuration of the plasma device of the embodiment. [Figure 7] It is a diagram showing a process flow indicating the manufacturing process for producing the carbon material of the embodiment.

Mode 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. Note 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 materials 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. The plant - based raw materials use plants, wood, etc., and in particular, discarded plant - based raw materials such as residues when harvesting plants can be used as raw materials for producing graphene, and raw materials can be obtained at low cost.

Table 1

[0013] Table 1 is a compositional table of plant-based raw materials. In Table 1, the proportion of the components that make up the raw material shown on the far left is shown in percentages from right to left. For example, rice straw contains 37.4% carbon (C), 0.53% nitrogen (N), 0.06% phosphorus (P), 0.14% phosphate (P2O5), 1.75% potassium (K), 2.11% potassium (K2O), 0.05% calcium (Ca), 0.19% magnesium (Mg), and 0.11% sodium (Na).

[0014] Here, porous plant-derived silicon-containing raw materials show virtually no change even when carbonized at low temperatures (above 300°C and below 1000°C), and the arrangement of pores can be maintained by removing silicon. Many plant-derived raw materials have a structure in which cells are regularly arranged along the axis, and silicic acid is deposited and thickened in the cell walls. Furthermore, there are compressed, narrow rows of cells between the silicified cell rows, and by removing silicon etc. after carbonization, it is possible to obtain a carbon material with a high specific surface area. As mentioned above, materials containing a high amount of silicic acid, between 13% and 35%, are suitable. Too much silicic acid will result in less graphene being obtained, so plant-derived raw materials with a silicic acid content in the range of around 20% are ideal.

[0015] Table 1 shows examples of plant-based raw materials that are rich in carbon. In addition to rice straw, these include wheat straw, barley straw, rice bran, rice husks, buckwheat straw, soybean straw, sweet potato vines, turnip leaves, carrot leaves, corn culms, sugarcane tops, coconut meal, peanut shells, mandarin orange peels, red cedar sawdust, larch bark, and ginkgo leaves. Alternatively, the plant material itself can be used instead of residues.

[0016] For example, bamboo is composed of cellulose, hemicellulose, and lignin as its cellulose fibers, and minerals such as iron, magnesium, calcium, manganese, copper, and nickel. In addition, when bamboo leaves are calcined, silanol groups (Si-OH) are extracted, and these are extracted as SiO4 during the calcination process.

[0017] [Table 2] [Table 3]

[0018] Tables 2 and 3 show the component composition of the plant-based raw material that is most suitable for producing carbon material among the carbon source 9 plant-based raw materials listed in Table 1 above in this invention. Table 2 shows the percentage of the components that make up the raw material. For example, moisture is 8% to 10%, ash is 10% to 18%, lipids are 0.1% to 0.5%, lignin is 18% to 25%, hemicellulose is 16% to 20%, cellulose is 30% to 35%, and others are 5% to 10%. Thus, the main components of silica ash 19 are lignin, hemicellulose, and cellulose.

[0019] Table 3 shows the inorganic chemical composition of carbon source 9, a plant-based raw material shown in Table 2. Carbon source 9, a plant-based raw material shown in Table 2, contains 80 wt% organic matter such as cellulose and 20 wt% inorganic matter. The inorganic chemical composition in Table 3 is as follows: SiO2 92.14 wt%, Al2O3 0.04 wt%, CaO 0.48 wt%, Fe2O3 0.03 wt%, K2O 3.2 wt%, MgO 0.16 wt%, MnO 0.18 wt%, and Na2O 0.09 wt%. Carbon source 9, a plant-based raw material shown in Table 2, contains a large amount of silicon dioxide (SiO2) as its inorganic component.

[0020] (Examples) <Process Flow> Referring to Figures 6 and 7, the manufacturing process for producing graphene 113 and carbide 19 will be described. Figure 7 is a diagram showing the process flow of the manufacturing process of an embodiment. First, in the pre-treatment step S1, after drying the plant-based raw material as described above, the plant-based raw material is crushed, and the crushed plant-based raw material and a granulating agent such as PVA are mixed with water in a ratio of 10:1 to knead the plant-based raw material to an appropriate size. The mixture is then heated to nearly 100°C on a drying device such as a hot plate to evaporate the water and generate the carbon source 9. Here, the crushing method can be a mill, mixer, grinder, etc. In particular, the granulating agent can prevent bumping due to steam from the carbon source 9 during induction heating.

[0021] Next, the carbonization process S2 will be explained. In the pretreatment process S1, approximately 0.8 g of the carbon source 9 is placed in the crucible 5 and covered with a metal mesh or the like. The crucible 5 is placed in the predetermined heating position of the plasma apparatus 10 described above. The pressure inside the chamber 1 is reduced to 80 Pa by the vacuum pump 30, and inert gas 6 is injected into the chamber 1 at a flow rate of 8 to 10 ml / min, so that the pressure inside the chamber 1 is maintained at 1300 to 1500 Pa. Note that the same graphene can be produced using the carbonization process S2 in Examples 1 and 3.

[0022] The highest yield of 36% was measured between 500°C and 800°C, and relatively high yields were obtained between 300°C and 1000°C. Similar results were obtained for rice straw, rice bran, coconut shells, rice husks, and peanut shells in this measurement. In the carbonization process S2, the carbon source 9 is carbonized in about 10 to 30 minutes by heating in the temperature range of 300°C to 1000°C using thermal plasma from arc discharge while introducing inert gas 6.

[0023] Next, the activation process S3 will be explained. The carbide 19 obtained above is mixed with potassium hydroxide in a ratio of 1:5 by weight, and the mixture is placed in a small crucible and covered. The small crucible is then placed inside the large crucible, and activated carbon is buried around it. The activated carbon is buried to prevent oxygen from entering the small crucible. The heating furnace was heated to a temperature of nearly 950°C and fired for about 2 to 3 hours.

[0024] Potassium hydroxide is used here to promote the removal of silicon and to improve the yield of the final product, graphene 113. 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, any lignin that has not been completely carbonized can be removed with an acid, using one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, PTSA, and aluminum chloride.

[0025] Of the carbides 19 reacted with potassium hydroxide, silicic acid reacts with potassium hydroxide to form potassium silicate. The remaining water-soluble potassium hydroxide (KOH) and potassium silicate are dissolved in water, and this mixture is placed in a filter paper and passed through a vacuum or reduced-pressure filter to remove silicon dioxide (silicon). In the subsequent drying and activation process S3, it was possible to produce graphene 113, a final product with a weight of approximately 1 / 8 to 1 / 10 of that when the initial plant-based raw material was granulated.

[0026] The plasma apparatus 10 of this embodiment will be described with reference to Figure 6. Figure 6 is a schematic diagram showing the configuration of the plasma apparatus 10 of this embodiment. The plasma apparatus 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, but other options include helium, neon, and nitrogen. The inert gas 6 can be filled into the chamber 1 via the introduction pipe 7 and 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 a control valve 22, and the vacuum pump 30 can reduce the pressure inside Chamber 1 to a vacuum state. An inert gas 6 is introduced into Chamber 1 via a valve connected to Chamber 1. A leak valve 23 is provided between the control valve 22 and Chamber 1 to release the vacuum inside Chamber 1 to atmospheric pressure. In addition, a control valve 14 and a leak valve 15 are provided between the outlet pipe 8, which introduces air into Chamber 1, and the vacuum pump 30, to release the vacuum inside Chamber 1 to atmospheric pressure.

[0029] Furthermore, the temperature control device 24 controls the high-frequency power supply 4 and manages the temperature maintenance and maintenance time inside the chamber 1. The plasma apparatus 10 in this embodiment is a method of obtaining thermal plasma by arc discharge by flowing argon gas, which is an inert gas 6, as a working gas under low pressure close to a vacuum, and passing a high current between the electrodes, cathode 2 and anode 3. A carbon crucible 5 is placed between cathode 2 and anode 3, and the crucible 5 contains a carbon source 9, which will be described later. The carbon source 9 is carbonized in about 10 to 30 minutes by heating to a temperature range of 300°C to 1000°C by the thermal plasma produced by arc discharge. In addition to the plasma apparatus described above, there are other methods of obtaining thermal plasma using barrier discharge, corona discharge, pulse discharge, and DC discharge.

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

[0031] In the case of induction heating, silicon dioxide (SiO₂) is included in the carbon source 9. 2 Even with insulating materials such as SiO2, the magnetic flux penetrates, the carbon source 9 becomes conductive, the carbon source 9 itself is heated, and the heating is accelerated, allowing it to carbonize in a short time. 2Insulators such as ) themselves are made of silicon dioxide (SiO2) to allow alternating magnetic flux to penetrate. 2 The substance itself is only heated from the storage box 205, and since it is not at a melting temperature, it remains as is, silicon dioxide (SiO2). 2 Many insulating materials remain, such as ).

[0032] (Graphene and carbides) The carbide 19 obtained in the carbonization step S2 and the graphene 113, which is a carbon material obtained in the activation step S3, produced according to the example are described below.

[0033] Figure 1 shows the Raman spectrum of graphene 113 obtained using the manufacturing apparatus of the present invention. Figure 2 shows the Raman spectrum of carbide 19 obtained using the manufacturing apparatus of the present invention. These figures were analyzed using a Raman spectrometer, and the obtained data is plotted with wavelength (wavenumber (Raman shift (cm) on the horizontal axis). -1 This is a Raman spectrum with intensity on the vertical axis.

[0034] Furthermore, as shown in Table 4, the G band (2850 cm²) is the peak wavelength obtained by Raman spectroscopy. -1 ) Peak values ​​IG and 2D band (1650cm) -1 This is the peak value ID of ).

[0035] As shown in Table 4, the value obtained by dividing IG by ID for graphene 113 is 1.68, indicating that it has fewer layers among the plant-based raw materials. In particular, it was confirmed that carbide 19 contains a large amount of silicon, and that oxygen-containing functional groups such as -OH, -CHO, and -COOH have been generated. The value obtained by dividing IG by ID for graphene-113 is preferably 0.9 or higher, and typically ranges from 0.9 to around 2.0.

[0036] The carbide 19 obtained in carbonization process S2 has a high ash content of 37.1 wt% after removing carbon, according to thermogravimetric analysis. Of this ash, silicon (Si) accounts for 24 wt% to 50 wt% of the total carbide 19. Other elements include K (0.51 wt% to 7 wt%), Al (0.1 wt% to 1.6 wt%), Ca (0.17 wt% to 0.5 wt%), and Fe (0.4 wt%), while Cr, Ni, Mn, Mg, P, S, and Na are all below 0.1 wt%.

[0037] The carbide 19 obtained in the carbonization process S2, which does not involve the so-called activation process S3, contains a large amount of silicon. When carbonized in an inert gas, it is not strongly reduced and becomes SiO2-x, which then combines with aromatic -OH groups in the form of -O-Si-OR to form a lignin polysaccharide complex, and is thought to readily take the form of C / SiOx.

[0038] Furthermore, the graphene 113 obtained in the activation process S3 described later has a high ash content excluding carbon, ranging from 1% to 24 wt% according to thermogravimetric analysis, of which silicon (Si) accounts for 1 to 20 wt% of the total graphene 113. Other elements include K at 4.3 wt%, Al at 1.5 wt%, Ca at 1.3 wt%, and Fe at 0.4 wt%, while P, Mn, Cl, S, and Mg are each at 0.1 wt% or less.

[0039] As described above, the silicon content of the carbon materials graphene 113 and carbide 19 ranges from 1 wt% to 50 wt%, indicating a high silicon content.

[0040] [Table 4] As shown in Table 4, the CO2 adsorption and desorption measurements confirmed that graphene 113 and carbide 19 have fine pores with a pore diameter mainly ranging from 0.8 nm to 2 nm.

[0041] Therefore, it is considered that it is easy 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. The micropore volume was 0.46 ml / g for graphene 113 and 0.27 ml / g for carbide 19.

[0042] Also, as shown in Table 4, the particles of graphene 113 or carbide 19 have a diameter distribution from 15 μm to 229 μm, and the median diameter shown by the median value of the integrated value of the distribution is about 110 μm.

[0043] Thus, a mesopore volume of 0.2 ml / g to 0.6 ml / g is formed. Especially, graphene 113 after the activation treatment for removing impurities described later shows a higher value, and it is considered that mesopores and micropores are growing due to the removal of silicon.

[0044] Also, as shown in Table 4, the specific surface area by the BET formula measured by the water vapor adsorption measurement method is 1792 m 2 / g for graphene 113, and this range is 890 m 2 / g to 2000 m 2 / g. For carbide 19, it is 726.4 m 2 / g, and this range is 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. Therefore, the adsorption effect of graphene 113 is enhanced.

[0045] Also, carbide 19 has a state in which the Si (silicon) of the elemental component is contained microscopically on the surface and inside of 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 carbide 19 in the state of Si (silicon) or silicon dioxide (SiO2). And by subjecting carbide 19 to an activation treatment, the purity of carbon increases and at the same time the specific surface area improves.

[0046] As shown in Table 4, the true density measured by the gas displacement density analyzer was 2.56 g / cm³ for graphene 113. 3 And carbide 19 is 2.27 g / cm³ 3 Furthermore, the bulk density of graphene-113 ranged from 0.21 to 0.29 g / cm³. 3 That was the case. Furthermore, the powder resistance values ​​measured by the double-ring method and the four-terminal method were 1.27 × 10 for carbide 19. 3~5 The ratio becomes Ω·cm, and by removing silicon, graphene-113 becomes 1.0 × 10⁻⁶. -2 The resistance becomes Ω·cm, improving conductivity. While a lower resistance is generally better, graphene-113 has a resistance of 1.0 × 10⁻⁶. -3 From Ω·cm to 3.8 × 10 -2 Ω·cm is optimal.

[0047] Furthermore, by retaining a large amount of silicon, the carbide 19 becomes more readily soluble in substances that readily adsorb silicon, and at the same time, its insulating performance is improved.

[0048] (Heat-generating paint) The following describes a heat-generating paint manufactured using the aforementioned carbon materials (carbide 19 and graphene 113) as pigments. The applicant has conducted tests on various types of paints to find the optimal conditions. The types of paints tested in this embodiment include two-component solvent-based paints, one-component solvent-based paints, and one-component water-based paints. [Table 5]

[0049] As shown in Table 5, the two-component solvent-based paint uses acrylic urethane as the binder and dilutes it with xylene as the solvent. The aforementioned carbon materials (carbide 19 and graphene 113) were used as pigments. This two-component solvent-based paint is a type of paint that is cured using a hardener.

[0050] The one-component solvent type uses silicone as the binder, xylene as the solvent, and the aforementioned carbon materials (carbide 19 and graphene 113) as the pigment. This one-component solvent type is heat-curing and has excellent heat resistance, with a heat resistance of up to 150°C.

[0051] The water-based, one-component type used an acrylic emulsion as the binder, water as the solvent, and the aforementioned carbon materials (carbide 19 and graphene 113) as the pigment. Furthermore, the binder was gradually added to the carbon material while dispersing, and the amount at which the stirred liquid remained liquid was determined as the limit. The weight-to-wt concentration (PWC value) of the pigment at that point was also calculated.

[0052] [Table 6] As shown in Table 6, each carbon material and each coating with a different PWC value were evaluated. First, 10g of each limiting liquid was placed on a tin plate, and the binder and hardener were mixed to achieve the set PWC value indicated in <>, then stirred with a spatula to form a coating. The dry film thickness was then measured. Visual inspection was also performed to determine the presence or absence of irregularities, cracks, and unevenness in color and gloss of the coating. ○ indicates that there are no such defects, △ indicates that one or more of these are present, and × indicates that there are noticeable defects.

[0053] Furthermore, film-forming ability is determined by a test in which the surface of the coating is scratched with a fingernail or similar object to see if the coating peels off. ○ indicates that there is no peeling, and × indicates that peeling occurs. Furthermore, the gloss value is the result of measuring the gloss value at 60 degrees. <1 indicates a value less than 1. Furthermore, film-forming ability is determined by a test to see if the coating peels off when the surface is scratched with a fingernail or similar object. ○ indicates no peeling, while × indicates peeling.

[0054] Flexibility was evaluated by forming a coating on paper and then folding the paper into a mountain fold to see if any cracks or fissures occurred at the top of the fold. ○ indicates that no cracks or fissures occurred, while × indicates that cracks or fissures occurred.

[0055] Next, the performance as a heat-generating paint will be explained. Figure 3 shows an insulator 51 such as paper, cloth, or plastic resin coated with the aforementioned solvent-based one-component heat-generating paint 50. A positive electrode 52 and a negative electrode 53 are provided at the central end of the heat-generating paint 50, and by supplying power to these electrodes, heat is generated from the area coated with the heat-generating paint 50. The distance L between the electrodes is 4.5 cm, and the area coated with the paint is 22.5 cm². 2 That is the case.

[0056] Figures 4 and 5 show the heat generation characteristics of the heat-generating paint 50. Figure 4 shows a graph of time (seconds) and temperature (°C) for a heating element with a coating thickness of 160 μm to 175 μm. V1 is the temperature graph measured at point P in Figure 3 when DC 20V was supplied. The power consumption ranged from 4 to 4.8 W, and the temperature rose from room temperature of 22.1°C to a maximum of approximately 62°C in about 300 seconds.

[0057] V2 is a temperature graph taken at point P in Figure 3 when DC12V was supplied. The power consumption ranged from 2 to 2.4W, and the temperature rose from room temperature of 26.3°C to a maximum of approximately 43.4°C in about 300 seconds.

[0058] Figure 5 shows a graph of time (seconds) and temperature (°C) for a heating element with a coating thickness of 60 μm to 75 μm. V1 is the temperature graph measured at point P in Figure 3 when DC 20V was supplied. The power consumption ranged from 1.6W to 2.0W, and the temperature rose from room temperature of 25.4°C to a maximum of approximately 44.1°C in about 280 seconds. V2 is a temperature graph taken at point P in Figure 3 when DC12V was supplied. The power consumption was 0.6W, and the temperature rose from room temperature of 25.4°C to a maximum of approximately 32.6°C in about 240 seconds.

[0059] Because carbon materials contain a large amount of silicon, there is no need to add inorganic materials later, and it is possible to improve the strength and electrical resistance of the paint. In particular, heat-generating paints that contain silicon in carbon materials can maintain the continuity of the paint film even when heated to high temperatures, making it possible to create highly heat-resistant surface heaters.

[0060] Furthermore, by mixing carbide 19, which contains many functional groups, with graphene 113 to create a pigment for paint, it is possible to supply not only DC but also high-voltage power such as AC while stabilizing the strength. In addition, the carbide 19, which contains many functional groups, facilitates dispersion and mixing in order to adjust the resistance value. The ideal mixing ratio is approximately 0.5:9.5 to 3:7 for carbide 19 to graphene 113. Also, the powder resistance is 1.0 × 10⁻⁶. -3 From Ω·cm to 3.8 × 10 -2 Carbon materials in the range of Ω·cm may be used individually, or they may be used in combination with other carbon materials. [Industrial applicability]

[0061] Regarding the industrial applications of the heat-generating paint of the present invention, in addition to being a heat-generating paint, it can also be used as a conductive paint for battery materials, semiconductors, heat dissipation materials, and the like. [Explanation of symbols]

[0062] 1 Chamber 2 Cathodes 3 Anodes 4 High frequency power supply 5 Crucible 6. Inert gas 7 Introductory pipe 8 Outlet pipe 9. Carbon sources 10 Plasma device 14 Control valve 15 Leak valve 19 Carbides 20 Control device 21 Gas volume control device 30 Vacuum pumps 50 Heat-generating paint 51 Insulator 52, 53 electrode 113 Graphene S1 Pretreatment process S2 Carbonization process S3 Activation process.

Claims

[Claim 1] A carbonization process in which plant-based raw materials containing 5% or more silicon are carbonized, The process involves adding a basic substance to the carbonized carbide and burning it, then dissolving the resulting combustion product in water, filtering it, and removing the silicon component. The product obtained from the activation step is graphene having a silicon weight percentage of 1% wt to 20% wt, a BET specific surface area of ​​890 m² / g to 2000 m² / g, and a powder resistance of 1.0 × 10⁻³ Ω·cm to 3.8 × 10⁻² Ω·cm. Using graphene as a pigment, The binder is gradually added while dispersing, and the amount of pigment added that maintains the liquid state of the stirred liquid is set to the limit. A method for producing an exothermic paint, characterized in that the binder, having a maximum pigment weight concentration of 33 wt%, is an acrylic emulsion, and the solvent is water.

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