A method for preparing graphene composite carbon spheres

Abstract

This invention relates to a graphene composite carbon sphere, its preparation method, and its application. The graphene composite carbon sphere is characterized by being an isotropic porous carbon sphere with high thermal and electrical conductivity. Its raw materials are graphene, graphene oxide, and graphite powder; the binder is asphalt and amine-cured thermoplastic phenolic resin; and it is prepared by a template-free, low-cost emulsification, dispersion, condensation, curing, and granulation process, followed by heating, drying, and high-temperature carbonization. The density of the graphene composite carbon sphere is 0.3~1.5 g / cm³. 3 The average particle size ranges from 30 to 150 μm.

Description

Technical Field

[0001] This invention relates to a method for preparing graphene composite carbon spheres, and particularly to a method for preparing graphene composite carbon spheres with high thermal conductivity, high electrical conductivity, lightweight and high strength. Background Technology

[0002] Graphene, as a thermally and electrically conductive additive, has begun to be widely used in rubber and plastics. As a two-dimensional material, graphene's enhancement of the composite properties of other materials is also two-dimensional, meaning its enhancement effect is significant in the in-plane direction, while performance decreases by two to three orders of magnitude in the direction perpendicular to the plane. Many applications require isotropic enhancement rather than anisotropic enhancement. Therefore, using various processing methods to achieve disordered and arbitrary orientation of graphene in the enhanced continuous phase has become an important approach. However, the two-dimensional shape of graphene is easily affected by the process, and in the high thermal and electrical conductivity state with high graphene concentration, graphene particles interfere with each other, making it impossible to achieve a disordered state.

[0003] Graphene spheres, as a novel material, have a wide range of applications. Besides serving as an additive in non-conductive thermally and electrically conductive materials, they can also be used as anode materials in lithium batteries and supercapacitors. There are various methods for producing graphene spheres, such as using spherical templates, emulsion-forming graphene spheres, and spray-forming graphene spheres. However, existing processes suffer from low production capacity, high cost, low density, and low thermal and electrical conductivity. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a three-dimensional graphene composite carbon sphere as a modifying additive. This additive is isotropic and does not exhibit anisotropy during the production process due to process orientation, and its density (porosity) is controllable. The main raw materials are low-cost industrial-grade materials, facilitating large-scale production.

[0005] This application provides a method for preparing graphene composite carbon spheres, wherein the graphene composite carbon spheres are isotropic porous carbon spheres with high thermal conductivity and high electrical conductivity, and the raw materials of the graphene composite carbon spheres include: graphene and / or graphene oxide, graphite powder, and binder. The adhesive is an asphalt and amine-cured thermoplastic phenolic resin, which is obtained by template-free emulsification, dispersion, condensation, curing and granulation, followed by heating, drying and high-temperature carbonization. The density of the graphene composite carbon spheres is 0.3~1.5 g / cm³. 3 The average particle size ranges from 30 to 150 μm.

[0006] Optionally, the adhesive raw materials include: butanol, phenolic resin, and asphalt; The raw material formula ratio of the graphene composite carbon ball is as follows: the weight ratio of asphalt: phenolic resin: graphene or graphene oxide: graphite powder: butanol is 100:30~150:50~200:100~200:30~150.

[0007] Optionally, the raw material formulation ratio of the graphene composite carbon sphere is asphalt: phenolic resin: graphene or graphene oxide: graphite powder: butanol in a weight ratio of 100:40~110:50~110:110~150:40~70.

[0008] Optionally, the formulation of the emulsified and dispersed aqueous solution is: deionized water: hexamethylenetetramine: polyvinyl alcohol in a weight ratio of 100:2~10:0.5~3.

[0009] Optionally, the formulation of the emulsified dispersion aqueous solution is: deionized water: hexamethylenetetramine: polyvinyl alcohol in a weight ratio of 100:3~7:0.5~3; Emulsify 20-40 liters of graphene composite solution with 100 liters of aqueous solution.

[0010] Optionally, the softening point / melting point of the adhesive asphalt and phenolic resin is 70~80℃, and they can be melted and stirred evenly together at high temperature; The curing agent for the phenolic resin is hexamethylenetetramine, which is soluble in deionized water to form an emulsified dispersion aqueous solution. During dispersion, it undergoes a condensation curing reaction with phenolic resin at the emulsion interface. The graphene or graphene oxide has a particle size range of 5~30μm; an aspect ratio better than 1000; and the graphite powder is a fine powder with a mesh size greater than 800.

[0011] Optionally, the graphene or graphene oxide has a particle size range of 7~15μm.

[0012] Optionally, the preparation method includes the following steps: (1) Preparation of graphene slurry: Heat asphalt and thermoplastic phenolic resin to form a mixed solution, add graphene or graphene oxide powder and graphite powder to form a uniform slurry, add n-butanol to adjust the viscosity and form an emulsifiable graphene slurry. (2) Dissolve polyvinyl alcohol and hexamethylenetetramine in deionized water and stir until homogeneous to form a dispersed aqueous solution; (3) The dispersion aqueous solution is introduced into the high-speed emulsification dispersion kettle, heated to 90°C, stirred at high speed, the linear velocity of the stirring dispersion disk is greater than 20m / s, the prepared 90°C graphene slurry is introduced, and it is emulsified. The emulsification conditions are adjusted to control the emulsification particle size of the slurry. The faster the speed, the smaller the average particle size, and the slower the speed, the larger the average particle size. (4) With continuous high-speed stirring, the phenolic resin gradually condenses and solidifies under the action of hexamethylenetetramine to form a three-dimensional network structure, forming insoluble and infusible composite spheres. The condensation reaction time is 60~240 min. (5) Centrifugation, dehydration, and filtration yielded a composite spherical powder wet cake; (6) Dry at 150℃ and pulverize to obtain composite powder; (7) The composite powder is carbonized in an inert atmosphere furnace to obtain graphene composite carbon powder. The carbonization temperature is 700~1500℃ and the carbonization time is 60~240min. (8) The slightly agglomerated composite powder obtained in step (7) is crushed by a pulverizer to obtain graphene composite carbon spheres with controllable particle size.

[0013] Optional production equipment includes industrial-grade mixers, emulsifying dispersers, dewatering machines, dryers, carbonization furnaces, and crushers / pulverizers to form a large-scale continuous production system.

[0014] Optionally, the graphene composite carbon spheres are combined with rubber and plastic to improve electrical and thermal conductivity, and the composite material with nylon has an electrical conductivity of 5~500 S / m.

[0015] This invention also provides a production equipment system for preparing isotropic, thermally conductive, electrically conductive, lightweight, and high-strength graphene composite carbon microspheres. The production equipment consists of conventional heating reaction kettles, high-speed emulsifiers, centrifugal dehydrators, and conveyor belt continuous dryers, high-speed pulverizers, and continuous or intermittent carbonization furnaces, which can easily achieve continuous large-scale production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the production equipment and process flow for the graphene composite sphere powder of the present invention.

[0017] Figure 2 Photographs of graphene composite carbon spheres produced using this invention.

[0018] Figure 3 Cross-sectional view of a flat plate prepared by combining graphene-carbon composite spheres with nylon.

[0019] Figure labels: 1. Ribbon mixing tank, 2. Mixing tank, 3. Emulsifying tank, 4. Continuous dehydrator, 5. Continuous crawler dryer, 6. Crusher 1, 7. Continuous crawler carbonization furnace, 8. Crusher. Detailed Implementation

[0020] The present invention will be described in more detail below with reference to the embodiments. It should be noted that the following embodiments are merely representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the following embodiments, and many variations are possible. All variations directly derived from or conceived of the content disclosed in the present invention should be considered within the scope of protection of the present invention.

[0021] In this invention, unless otherwise specified, all parts and percentages are by weight, and all equipment and raw materials are commercially available or commonly used in the industry. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0022] Specifically, the inventors provide the following technical solutions: This invention first provides a process for preparing isotropic, thermally conductive, electrically conductive, lightweight, and high-strength graphene composite carbon microspheres. The process involves mixing asphalt with a melting / softening point of 70-80°C with a thermoplastic phenolic resin of the same softening point to form a mixed solution. Graphene or graphene oxide powder and graphite powder of 800 mesh or finer are then added to form a homogeneous slurry. The particle size range of the graphene and graphene oxide is 5-30 μm, preferably 7-15 μm, with an aspect ratio better than 1000. Butanol is added to adjust the viscosity, forming an emulsifiable slurry. Polyvinyl alcohol and hexamethylenetetramine are dissolved in deionized water and stirred evenly in a mixing tank. The aqueous solution is then introduced into a high-speed emulsification dispersion vessel, heated to 90°C, and stirred at high speed (the linear velocity of the stirring and dispersion disc is greater than 20 m / s). The prepared slurry is then introduced and emulsified. The emulsification conditions are adjusted to control the emulsified particle size; a faster speed results in a smaller average particle size, while a slower speed results in a larger average particle size. Phenolic resin gradually condenses and solidifies under the action of hexamethylenetetramine to form a three-dimensional network structure, resulting in insoluble and infusible composite spheres. The condensation reaction time is 60–240 min. Centrifugation and filtration yield a wet cake of composite spherical powder, which is then dried at 150℃ and dispersed to obtain composite spherical powder. This composite spherical powder is then carbonized in a continuous furnace under an inert atmosphere to obtain graphene composite carbon spherical powder. The carbonization temperature is 700–1500℃, the carbonization time is 60–240 min, and the density of the composite powder is 0.3–1.5 g / cm³. 3 The average particle size ranges from 30 to 150 μm, and the thermal and electrical conductivity of the spherical powder increases with higher temperature.

[0023] The present invention further provides a production formula for isotropic, thermally conductive, electrically conductive, lightweight, and high-strength graphene composite carbon microspheres. The graphene resin composite solution is prepared in the following weight ratio: asphalt: phenolic resin: graphene: graphite powder: butanol, which is 100:30~150:50~200:100~200:30~150. The curing agent aqueous solution is prepared in the following weight ratio: deionized water: hexamethylenetetramine: polyvinyl alcohol, which is 100:2~10:0.5~3, preferably 100:3~7:0.5~3. 100 liters of aqueous solution can emulsify 20~40 liters of composite solution. Asphalt composed of polycyclic aromatic hydrocarbons readily forms graphene structures upon carbonization, creating highly thermally and electrically conductive structures with graphite powder and other materials. However, it melts during carbonization, requiring a special non-melting process to ensure the independent carbonization of the asphalt spheres. Adding a phenolic composite formulation forms insoluble and infusible graphene + graphite powder + phenolic + asphalt composite particles during the curing process, exhibiting stable morphology during drying and carbonization. Adding graphite powder reduces costs, and its low aspect ratio facilitates the formation of disordered structures.

[0024] Graphene composite carbon spheres are mixed with thermoplastic powders such as nylon powder and hot-pressed to form thermally and electrically conductive parts with a density of 0.6~1.3 g / cm³. 3 Electrical conductivity 5~500 S / m. Example

[0025] like Figure 1As shown, this invention first provides a method for preparing isotropic, thermally conductive, electrically conductive, lightweight, and high-strength graphene composite carbon microspheres. The method involves heating a mixing vessel to 90°C, adding asphalt with a melting / softening point of 70-80°C and thermoplastic phenolic resin (e.g., Shengquan phenolic resin), and stirring to form a homogeneous solution. Then, graphene or graphene oxide powder and graphite powder of 800 mesh or finer are added to form a homogeneous slurry. The graphene particle size range is 10 μm, and the aspect ratio is better than 1000. Butanol is added to adjust the viscosity, forming an emulsifiable slurry. The graphene resin composite solution has the following weight ratio: asphalt: phenolic resin: graphene: graphite powder: butanol = 100:50:70:120:40. A curing agent aqueous solution is prepared in a mixing tank with the following weight ratio: deionized water: hexamethylenetetramine: polyvinyl alcohol = 100:4:1. The curing agent aqueous solution was introduced into a high-speed emulsification dispersion vessel, heated to 90℃, and stirred at a high speed of 25 m / s. A prepared slurry at 90℃ was then introduced, and 30 liters of composite solution were added to 100 liters of aqueous solution and emulsified. The condensation reaction was carried out for 90 minutes, gradually solidifying to form a three-dimensional network structure, resulting in insoluble and infusible composite spheres. The composite spherical powder wet cake was obtained by centrifugation and filtration, dried and dispersed at 150℃ to obtain composite spherical powder. The composite spherical powder was then carbonized in an inert atmosphere continuous furnace to obtain graphene composite carbon spherical powder. The carbonization temperature was 1200℃, and the carbonization time was 120 minutes, resulting in a composite powder density of 0.5 g / cm³. 3 The average particle size is 90 μm. Figure 2 ).

[0026] The obtained graphene composite carbon spheres were mixed with nylon 66 at a weight ratio of 1:1, and then hot-pressed into parts. Figure 3 The density of the flat part was found to be 0.8 g / cm³. 3 It has an electrical conductivity of 10 S / m, and the thickness has the same electrical conductivity as the in-plane direction. Example

[0027] Using the same equipment, process conditions, and raw materials as in Example 1, but with different grades of graphene and formulation ratios, the mixing vessel was heated to 90°C. Asphalt with a melting / softening point of 70-80°C and thermoplastic phenolic resin, such as Shengquan phenolic resin, were added and stirred to form a homogeneous mixture. Graphene or graphene oxide powder and graphite powder of 800 mesh or finer were then added to form a homogeneous slurry. The graphene particle size range was 7 μm, and the aspect ratio was better than 1000. Butanol was added to adjust the viscosity, forming an emulsifiable slurry. The graphene resin composite solution was prepared with a weight ratio of asphalt:phenolic resin:graphene:graphite powder:butanol of 100:60:100:110:45. A curing agent aqueous solution was prepared in the mixing tank with a weight ratio of deionized water:hexamethylenetetramine:polyvinyl alcohol of 100:5:1. The curing agent aqueous solution was introduced into a high-speed emulsification dispersion vessel, heated to 90℃, and stirred at a high speed of 25 m / s. A prepared slurry at 90℃ was then introduced, and 30 liters of composite solution were added to 100 liters of aqueous solution and emulsified. The condensation reaction was carried out for 150 min, gradually solidifying to form a three-dimensional network structure, resulting in insoluble and infusible composite spheres. The composite spherical powder wet cake was obtained by centrifugation and filtration, dried and dispersed at 150℃ to obtain composite spherical powder. The composite spherical powder was then carbonized in an inert atmosphere continuous furnace to obtain graphene composite carbon spherical powder. The carbonization temperature was 1000℃, and the carbonization time was 180 min, resulting in a composite powder density of 0.45 g / cm³. 3 The average particle size is 70 μm.

[0028] The obtained graphene composite carbon spheres were mixed with nylon 66 at a weight ratio of 1:1, and then hot-pressed to obtain a flat part with a density of 0.7 g / cm³. 3 It has an electrical conductivity of 20 S / m, and the thickness has the same electrical conductivity as the in-plane direction. Example

[0029] Using the same equipment, process conditions, and raw materials as in Example 1, but with different grades of graphene and formulation ratios, the mixing vessel was heated to 90°C. Asphalt with a melting / softening point of 70-80°C and thermoplastic phenolic resin, such as Shengquan phenolic resin, were added and stirred to form a homogeneous solution. Graphene or graphene oxide powder and graphite powder of 800 mesh or finer were then added to form a homogeneous slurry. The graphene particle size range was 15 μm, and the aspect ratio was better than 1000. Butanol was added to adjust the viscosity, forming an emulsifiable slurry. The graphene resin composite solution was prepared with a weight ratio of asphalt:phenolic resin:graphene:graphite powder:butanol of 100:80:60:130:50. A curing agent aqueous solution was prepared in the mixing tank with a weight ratio of deionized water:hexamethylenetetramine:polyvinyl alcohol of 100:6:1. The curing agent aqueous solution was introduced into a high-speed emulsification dispersion vessel, heated to 90℃, and stirred at a high speed of 25 m / s. A prepared slurry at 90℃ was then introduced, and 30 liters of composite solution were added to 100 liters of aqueous solution and emulsified. The condensation reaction was carried out for 120 min, gradually solidifying to form a three-dimensional network structure, resulting in insoluble and infusible composite spheres. The composite spherical powder wet cake was obtained by centrifugation and filtration, dried and dispersed at 150℃ to obtain composite spherical powder. The composite spherical powder was then carbonized in an inert atmosphere continuous furnace to obtain graphene composite carbon spherical powder. The carbonization temperature was 1000℃, and the carbonization time was 180 min, resulting in a composite powder density of 0.65 g / cm³. 3 The average particle size is 95 μm.

[0030] The obtained graphene composite carbon spheres were mixed with nylon 66 at a weight ratio of 1.5:1, and then hot-pressed to obtain a flat part with a density of 1.05 g / cm³. 3 It has an electrical conductivity of 150 S / m, and the thickness has the same electrical conductivity as the in-plane direction.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing graphene composite carbon spheres, characterized in that, The preparation method includes the following steps: (1) Preparation of graphene slurry: Heat asphalt and thermoplastic phenolic resin to form a mixed solution, add graphene or graphene oxide powder and graphite powder to form a uniform slurry, add n-butanol to adjust the viscosity and form an emulsifiable graphene slurry; (2) Dissolve polyvinyl alcohol and hexamethylenetetramine in deionized water and stir until homogeneous to form a dispersed aqueous solution; (3) The dispersion aqueous solution is introduced into the high-speed emulsification dispersion kettle, heated to 90°C, stirred at high speed, the linear velocity of the stirring dispersion disk is greater than 20m / s, the prepared 90°C graphene slurry is introduced, and it is emulsified. The emulsification conditions are adjusted to control the emulsification particle size of the slurry. The faster the speed, the smaller the average particle size, and the slower the speed, the larger the average particle size. (4) With continuous high-speed stirring, the phenolic resin gradually condenses and solidifies under the action of hexamethylenetetramine to form a three-dimensional network structure, forming insoluble and infusible composite spheres. The condensation reaction time is 60~240 min. (5) Centrifugation, dehydration, and filtration yielded a composite spherical powder wet cake; (6) Dry at 150℃ and pulverize to obtain composite powder; (7) The composite powder is carbonized in an inert atmosphere furnace to obtain graphene composite carbon powder. The carbonization temperature is 700~1500℃ and the carbonization time is 60~240min. (8) The slightly agglomerated composite powder obtained in step (7) is crushed by a pulverizer to obtain graphene composite carbon spheres with controllable particle size.

2. The method for preparing graphene composite carbon spheres as described in claim 1, characterized in that, The production equipment used in the preparation method includes industrial-grade mixers, emulsifying dispersers, dehydrators, dryers, carbonization furnaces, and crushers / pulverizers, in order to form a large-scale continuous production system.

3. A graphene composite carbon sphere prepared by the method according to claim 1, characterized in that, The graphene composite carbon spheres are isotropic porous carbon spheres with high thermal conductivity and high electrical conductivity. The raw materials of the graphene composite carbon spheres include: graphene and / or graphene oxide, graphite powder, and binder. The adhesive is an asphalt and amine-cured thermoplastic phenolic resin, which is obtained by template-free emulsification, dispersion, condensation, curing and granulation, followed by heating, drying and high-temperature carbonization. The density of the graphene composite carbon spheres is 0.3~0.65 g / cm³. 3 The average particle size ranges from 30 to 150 μm.

4. The graphene composite carbon sphere according to claim 3, characterized in that, The adhesive raw materials include: butanol, phenolic resin, and asphalt; The raw material formula ratio of the graphene composite carbon ball is as follows: the weight ratio of asphalt: phenolic resin: graphene or graphene oxide: graphite powder: butanol is 100:30~150:50~200:100~200:30~150.

5. The graphene composite carbon sphere according to claim 3, characterized in that, The raw material formula ratio of the graphene composite carbon ball is as follows: the weight ratio of asphalt: phenolic resin: graphene or graphene oxide: graphite powder: butanol is 100:40~110:50~110:110~150:40~70.

6. The graphene composite carbon sphere according to claim 3, characterized in that, The formulation of the emulsified dispersion aqueous solution is as follows: the weight ratio of deionized water: hexamethylenetetramine: polyvinyl alcohol is 100: 2~10: 0.5~3.

7. The graphene composite carbon sphere according to claim 6, characterized in that, The formulation of the emulsified dispersion aqueous solution is as follows: the weight ratio of deionized water: hexamethylenetetramine: polyvinyl alcohol is 100:3~7:0.5~3; Emulsify 20-40 liters of graphene composite solution with 100 liters of aqueous solution.

8. The graphene composite carbon spheres as described in claim 3, characterized in that, The softening point / melting point of the adhesive asphalt and phenolic resin is 70~80℃, and they can be melted and stirred evenly together at high temperature; The curing agent for the phenolic resin is hexamethylenetetramine, which is soluble in deionized water to form an emulsified dispersion aqueous solution. During dispersion, it undergoes a condensation curing reaction with phenolic resin at the emulsion interface. The graphene or graphene oxide has a particle size range of 5~30μm; an aspect ratio better than 1000; and the graphite powder is a fine powder with a mesh size greater than 800.

9. The graphene composite carbon spheres as described in claim 8, characterized in that, The graphene or graphene oxide has a particle size range of 7~15μm.

10. An application of the graphene composite carbon sphere according to any one of claims 3-9, characterized in that, This is used to improve the electrical and thermal conductivity of the graphene composite carbon spheres when combined with rubber and plastic.

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