Thermal conductive agent, method for producing the same, and elastomer

Abstract

This application provides a thermal conductive agent, its preparation method, and an elastomer. The preparation method includes: providing graphene material, an oxidant, and a polymer material; mixing the graphene material and the oxidant in a certain proportion to obtain a mixture; subjecting the mixture to mechanochemical treatment, cleaning, and drying to obtain edge-hydroxylated graphene; mixing the edge-hydroxylated graphene with the polymer material in a certain proportion and performing an exfoliation process to obtain the thermal conductive agent. Using the preparation method provided in this application, the oxidant can capture electrons from the edge carbons of the graphene under the action of mechanical energy, introducing hydroxyl functional groups at the edges of the graphene sheets. This improves the compatibility of graphene and the polymer material during subsequent exfoliation, while maintaining the complete π-π conjugated structure in the middle of the graphene, which is beneficial for the transport of electrons and phonons, giving the thermal conductive agent high thermal conductivity, high carrier mobility, and excellent mechanical strength.

Description

Technical Field

[0001] This application relates to the field of polymer modification technology, specifically to a thermal conductive agent, its preparation method, and an elastomer. Background Technology

[0002] With the rapid development of the automotive industry, solid tires have been widely used in industrial vehicles, military vehicles, construction machinery, and other fields due to their advantages such as high load-bearing capacity, wear resistance, and no need for inflation. However, during operation, solid tires generate a large amount of heat under cyclic stress due to the viscoelastic properties of the elastomer material, leading to an increase in the internal temperature of the tire.

[0003] Elastomers are poor conductors of heat, making it difficult for heat to dissipate quickly within them, leading to heat accumulation and the formation of localized high-temperature zones. This heat accumulation can cause safety hazards and significantly weaken the performance of the elastomer, resulting in the following problems: First, elastomers undergo thermo-oxidative aging at high temperatures, leading to increased material hardness, decreased elasticity, and accelerated crack propagation, significantly shortening the elastomer's service life; second, high temperatures reduce the adhesive strength between the elastic material and the reinforcing material, resulting in a decrease in the structural integrity of the elastomer.

[0004] To address the heat dissipation problem of elastomers, thermally conductive fillers can be added to the elastomer matrix to improve the thermal conductivity of the composite material. However, traditional thermally conductive fillers suffer from problems such as large addition amounts, difficulty in dispersion, and poor processing performance. Furthermore, directly adding powdered thermally conductive fillers can cause a sharp increase in the viscosity of the elastic material, resulting in poor processing fluidity and uneven powder dispersion, which leads to stress concentration in the elastomer and severely affects its mechanical properties. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this application provides a thermally conductive agent, its preparation method, and an elastomer. The specific technical solution is as follows: On the one hand, this application provides a method for preparing a thermally conductive agent, comprising: We provide graphene materials, oxidants, and polymer materials. The graphene material and the oxidant are mixed in a certain proportion to obtain a mixture; The mixture was subjected to mechanochemical treatment, washing, and drying to obtain edge-hydroxylated graphene; The edge-hydroxylated graphene is mixed with the polymer material in a certain proportion and then exfoliated to obtain the thermal conductive agent.

[0006] In a possible implementation, the mass ratio of the graphene material to the oxidant in the mixture is (3-1):(7-9).

[0007] In a possible implementation, the mass ratio of the edge-hydroxylated graphene to the polymer material in the thermal conductive agent is (4-1):(6-19).

[0008] In a possible implementation, the graphene material satisfies at least one of the following characteristics: The graphene material includes at least one of single-layer graphene, double-layer graphene, few-layer graphene, and multilayer graphene. The graphene material has a sheet diameter of 0.5-50 μm; The graphene material has a carbon content of 95% or greater.

[0009] In a possible implementation, the oxidant includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, and hypochlorous acid.

[0010] In a possible implementation, the mechanochemical treatment is a ball milling treatment, which satisfies at least one of the following characteristics: The ball-to-material ratio for the ball milling process is (30-50):(1-2); The ball milling process is performed at a speed of 300-400 rpm; The ball milling process takes 60-180 minutes.

[0011] In a possible implementation, the stripping process satisfies at least one of the following characteristics: The pressure for the stripping process is 50-80 MPa; The stripping process takes 30-90 minutes.

[0012] In a possible implementation, the polymeric material includes at least a polyether polyol.

[0013] On the other hand, this application also provides a thermal conductive agent prepared by any one of the preparation methods described in the above embodiments.

[0014] On the other hand, this application also provides an elastomer comprising an elastic material and a thermally conductive agent prepared by the preparation method as described in any one of the above embodiments.

[0015] Based on the above technical solution, this application has the following beneficial effects: This application provides a method for preparing a thermal conductive agent, comprising: providing graphene material, an oxidant, and a polymer material; mixing the graphene material and the oxidant in a certain proportion to obtain a mixture; subjecting the mixture to mechanochemical treatment, cleaning, and drying to obtain edge-hydroxylated graphene; mixing the edge-hydroxylated graphene with the polymer material in a certain proportion and performing an exfoliation treatment to obtain the thermal conductive agent. Using the preparation method provided in this application, the oxidant can capture electrons from the edge carbons of the graphene under the action of mechanical energy, introducing hydroxyl functional groups at the edges of the graphene sheets, improving the compatibility between graphene and the polymer material during subsequent exfoliation treatment, while maintaining the complete π-π conjugated structure in the middle of the graphene, which is beneficial for electron and phonon transport, giving the thermal conductive agent high thermal conductivity, high carrier mobility, and excellent mechanical strength; subsequently, the edge-hydroxylated graphene is exfoliated in situ from the polymer material through the exfoliation treatment, where the hydroxyl groups can form strong interactions such as hydrogen bonds with the polymer chains, strengthening interfacial adhesion and improving the uniformity of the thermal conductive agent. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This application provides a flowchart of a method for preparing a thermally conductive agent. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that, in the description of this application, the following definitions shall apply unless a different definition is given elsewhere in the claims or this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated values ​​to produce substantially the same properties, functions, results, etc. A range of numerical values ​​indicated by a low value and a high value is defined as including all numerical values ​​within that range and all subranges included within that range.

[0020] It should be noted that the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0021] The following describes a method for preparing a thermally conductive agent according to embodiments of this application. This specification provides the method steps as described in the embodiments, but based on conventional or non-inventive methods, more or fewer steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many steps and does not represent the only possible execution order. In actual implementation of the preparation method, it can be executed in the order shown in the embodiments or accompanying drawings, or in parallel. The method for preparing the thermally conductive agent may include S1-S4: S1: Provides graphene materials, oxidants, and polymer materials.

[0022] Understandably, graphene has high intrinsic thermal conductivity and a two-dimensional sheet structure. The sheet structure can overlap in a group to form an efficient heat conduction network, enabling rapid heat dissipation.

[0023] In possible implementations, the graphene material includes at least one of monolayer graphene, bilayer graphene, few-layer graphene, and multilayer graphene. Monolayer graphene has high thermal conductivity and a large specific surface area, resulting in high efficiency in constructing thermally conductive networks. It can form effective thermally conductive pathways with low addition amounts and has minimal impact on the original properties of the matrix. Bilayer and few-layer graphene have high in-plane thermal conductivity and are easy to overlap. Multilayer graphene has lower cost, generally better dispersibility than monolayer graphene, and good processing performance. Few-layer graphene is used to indicate graphene materials with 3-10 layers, and multilayer graphene is used to indicate graphene materials with 11-30 layers.

[0024] Specifically, the sheet diameter of the graphene material is 0.5-50 μm; understandably, the sheet diameter can be any value within the range of 0.5-50 μm; for example, the sheet diameter can be 0.5 μm, 1 μm, 5 μm, 10 μm, 25 μm, 40 μm, 45 μm, 50 μm, etc. Controlling the sheet diameter of the graphene material within the above range ensures that, even with low addition amounts, the graphene sheets form continuous thermal conductive pathways, achieving efficient heat conduction and significantly improving overall thermal conductivity. If the sheet diameter of the graphene material is smaller than the above range, the amount of graphene material added needs to be increased to form an effective network; if the sheet diameter of the graphene material is larger than the above range, the graphene material is difficult to disperse uniformly, leading to local agglomeration or the formation of defects, increasing interfacial thermal resistance and affecting thermal conductivity. Preferably, the sheet diameter of the graphene material is 0.5-20 μm.

[0025] Specifically, the graphene material has a carbon content of ≥95%, ensuring a high degree of graphitization, few structural defects, and low impurity content. This prevents impurities and defects from becoming phonon scattering centers and hindering heat transfer. High-purity graphene material itself has excellent thermal conductivity and maintains chemical inertness, preventing thermo-oxidative aging and contributing to improved reliability and durability of the elastomer during long-term use. Preferably, the graphene material has a carbon content of ≥99%.

[0026] In the application of graphene materials, excessively high levels of impurities and functional groups cause uncontrollable changes in the surface properties of graphene, affecting its interfacial compatibility, adhesion strength, and dispersion uniformity with elastic materials such as polyurethane. High-purity graphene materials provide a uniform and controllable surface, which is beneficial for precise control of the interface through modification treatment, enhancing thermal conductivity while taking mechanical properties into account.

[0027] In a possible implementation, the oxidant includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, and hypochlorous acid. Using the above-mentioned oxidant can controllably oxidize and modify graphene materials, introduce active groups on their surface, and improve the interfacial adhesion between graphene materials and elastic materials.

[0028] In possible implementations, the polymer material includes at least a polyether polyol. Polyether polyols are excellent dispersion media; the hydroxyl groups at the ends of the polyether polyol molecular chains can form hydrogen bonds with the hydroxyl groups of the edge-hydroxyled graphene, effectively inhibiting the re-aggregation of the graphene sheets and ensuring their uniform and stable dispersion within the polyol system. Subsequently, during the application of the thermal conductive agent in the elastomer, the graphene sheets with polymer chains grafted onto their surfaces can be more uniformly distributed within the elastomer matrix and interlock to form highly efficient three-dimensional thermal conduction pathways.

[0029] S2: Mix graphene material and oxidant in a certain proportion to obtain a mixture.

[0030] In a possible implementation, the mass ratio of graphene material to oxidant in the mixture is (3-1):(7-9); understandably, the mass ratio of graphene material to oxidant in the mixture can be any value within (3-1):(7-9); exemplaryly, the mass ratio of graphene material to oxidant in the mixture can be 3:7, 3:8, 3:9, 1:7, 1:9, 2:8, 2:7, etc. Controlling the mass ratio of graphene material to oxidant within the above range can provide a good oxidation environment for the reaction system, effectively control the degree of oxidation reaction, and facilitate the preparation of edge-hydroxylated graphene with uniform properties. Preferably, the mass ratio of graphene material to oxidant in the mixture is (3-2):(7-8).

[0031] In some embodiments, the graphene material is multilayer graphene, the oxidant is potassium persulfate, and the mass ratio of multilayer graphene to potassium persulfate in the mixture is (3-2):(7-8). Multilayer graphene has strong interlayer interaction forces. By controlling the mass ratio of multilayer graphene to potassium persulfate within the above range, sufficient and continuous oxidizing free radicals can be provided to ensure effective chemical modification of multilayer graphene.

[0032] Preferably, the sheet diameter of the multilayer graphene is 5-20 μm, and the carbon content of the multilayer graphene is greater than or equal to 99%. Understandably, the sheet diameter of the multilayer graphene can be any value within the range of 5-20 μm, and the carbon content of the multilayer graphene can be any value greater than or equal to 99%. The larger sheet diameter makes it easier for the graphene to contact and overlap with each other in the matrix, forming an effective three-dimensional thermal conductivity pathway. The high-purity multilayer graphene has a complete crystal structure with fewer defects, which can ensure that the pathway nodes have high thermal conductivity.

[0033] S3: The mixture is subjected to mechanochemical treatment, washing, and drying to obtain edge-hydroxylated graphene.

[0034] Specifically, during the mechanochemical processing, the graphene sheets are subjected to physical impacts of mechanical shearing and compression, causing the graphene sheets to peel off and shrink in size, exposing more graphene edges, which in turn generate new structural defects at the edges. The carbon atoms at the newly exposed edges and defects are highly reactive and can provide preferential sites for subsequent chemical reactions.

[0035] With the assistance of mechanical energy, the oxidant can selectively react with highly active edge carbon atoms. By controlling the amount of oxidant, the reaction time, and the intensity of mechanical force, the target functional group mainly generated by the reaction can be guided to be hydroxyl, and the hydroxyl groups can be aggregated at the edge of graphene, rather than destroying the basal sp² structure of graphene over a large area.

[0036] In some embodiments, the oxidant includes at least one of sodium persulfate, potassium persulfate, and ammonium persulfate. Persulfate can generate sulfate radicals under the action of mechanical energy. During the reaction, it can capture electrons from the edge carbons of the graphene material to form carbocations or carbon radicals and undergo nucleophilic addition with hydroxide ions to form hydroxyl groups.

[0037] Specifically, the free radicals and intercalation ions generated by the decomposition of potassium persulfate under mechanical grinding can be inserted into the interlayer of multilayer graphene, and promote interlayer exfoliation in conjunction with mechanical shear force, which helps to achieve in-situ exfoliation of multilayer graphene in subsequent preparation processes.

[0038] Specifically, edge-hydroxylated graphene is a functionalized graphene material that has undergone specific chemical modification. Through a controlled chemical reaction, hydroxyl functional groups can be selectively introduced at the edges of graphene sheets while maintaining the two-dimensional honeycomb lattice structure of graphene. This gives edge-hydroxylated graphene the high intrinsic thermal conductivity, high carrier mobility, and excellent mechanical strength of the original graphene material. The hydroxyl groups at the edges can improve the dispersion stability of the material in a polar polymer matrix and can form chemical bonds with active groups in the matrix, enhancing interfacial adhesion and reducing interfacial thermal resistance. The complete basal structure ensures graphene's excellent phonon transport capability, enabling it to efficiently construct thermally conductive pathways when used as a thermally conductive filler.

[0039] In possible implementations, mechanochemical treatment is used to directly induce or accelerate chemical reactions using mechanical energy. Methods for mechanochemical treatment include, but are not limited to, ball milling, grinding, high-shear treatment, twin-screw extrusion, and ultrasonic-assisted mechanochemical treatment.

[0040] In a possible implementation, the mechanochemical treatment is ball milling, with a ball-to-material ratio of (30-50):(1-2). Understandably, the ball-to-material ratio can be any value within (30-50):(1-2); exemplary examples include ball-to-material ratios of 30:1, 30:2, 32:1, 35:1, 40:1, 45:2, 47:2, and 50:1. Controlling the ball-to-material ratio within the above range ensures that the total mass of the grinding balls is much greater than the reactants, generating intense collisions and shearing during the reaction. This provides sufficient energy for edge activation of the graphene material and the chemical reaction between the graphene material and the oxidant, and promotes uniform mixing of the reactants, improving the uniformity of the product. Preferably, the ball-to-material ratio is (40-50):(1-2).

[0041] Specifically, the ball milling speed is 300-400 rpm; understandably, the ball milling speed can be any value within 300-400 rpm; for example, the ball milling speeds are 300 rpm, 320 rpm, 350 rpm, 390 rpm, 400 rpm, etc. Controlling the ball milling speed within this range generates sufficient collision and shear forces to ensure effective edge activation of the graphene sheets, limiting mechanochemical action primarily to the edges and defects of the graphene, effectively facilitating edge hydroxylation reactions; and avoiding excessively high speeds that could damage the intact graphene basal surfaces. 2 The structure is damaged. Preferably, the ball milling speed is 350-400 rpm.

[0042] Specifically, the ball milling time is 60-180 min; understandably, the ball milling time can be any value within the range of 60-180 min; for example, the ball milling time can be 60 min, 65 min, 70 min, 90 min, 100 min, 150 min, 170 min, 175 min, 180 min, etc. Controlling the ball milling time within the above range ensures a sufficient and complete reaction, achieving the desired degree of functionalization and obtaining a product with edge hydroxylation and good structural integrity. Preferably, the ball milling time is 90-120 min.

[0043] Understandably, the time parameter and energy intensity parameter of ball milling work together. The energy intensity is determined by the ball-to-material ratio and the ball mill speed. The ball milling time, ball-to-material ratio, and speed together control the total amount of mechanical energy transferred to the material. The ball-to-material ratio, speed, and time can be adjusted within the above parameter range according to the actual application.

[0044] In some embodiments, the mixture includes multilayer graphene, and the ball milling speed is 350-400 rpm, and the ball milling time is 120-180 min. This ensures that the kinetic energy of the grinding balls can apply sufficient shear and impact forces to the multilayer graphene, effectively exfoliating the graphene sheets and breaking up large particles, increasing the specific surface area and edge exposure of the graphene; and avoiding excessive fragmentation of the graphene sheets, which would damage the crystal structure. This is beneficial for obtaining multilayer graphene with fewer layers and hydroxyl-rich edges.

[0045] In a possible implementation, the mixture is subjected to mechanochemical treatment to obtain a mixed product; the mixed product is then repeatedly washed and dried to obtain edge-hydroxylated graphene. Specifically, the mixed product is washed with deionized water, and solid-liquid separation is achieved by centrifugation or filtration to fully remove unreacted oxidants and obtain pure edge-hydroxylated graphene.

[0046] S4: Edge-hydroxylated graphene is mixed with polymer materials in a certain proportion and then exfoliated to obtain a thermal conductive agent.

[0047] Specifically, during the exfoliation process, the van der Waals forces between graphene sheets can be effectively overcome, disrupting the agglomeration of graphene. Under shear force, the graphene sheets are further exfoliated in the viscous polymer material, forming thinner sheets or monolayers, increasing their effective specific surface area. Furthermore, the in-situ exfoliation method allows graphene to be better dispersed in polyether polyols. Compared with traditional stirring dispersion processes, high-pressure exfoliation dispersion can solve the problem of low filler content in high-viscosity substrates.

[0048] In a possible implementation, the mass ratio of edge-hydroxylated graphene to polymeric material in the thermal conductive agent is (4-1):(6-19). Understandably, any value within the range of (4-1):(6-19) is acceptable for this ratio. Exemplary examples include mass ratios of 4:6, 4:7, 4:11, 3:17, 2:13, 1:18, and 1:19. Controlling the mass ratio of edge-hydroxylated graphene to polymeric material within this range ensures effective dispersion of the edge-hydroxylated graphene while maintaining good thermal conductivity in the thermal conductive agent. Understandably, the mass ratio of edge-hydroxylated graphene to polymeric material can be adjusted within this range according to the specific application requirements.

[0049] Specifically, the polymer material can be a polyether polyol, which can form hydrogen bonds with the hydroxyl groups of the edge-hydroxylated graphene, allowing it to be uniformly and stably dispersed in the polyol system, thus facilitating the formation of efficient thermal conduction pathways. Preferably, the mass ratio of edge-hydroxylated graphene to polyether polyol is 1:2.

[0050] In a possible implementation, the exfoliation pressure is 50-80 MPa; understandably, the exfoliation pressure can be any value within the 50-80 MPa range; exemplary values ​​include 50 MPa, 52 MPa, 55 MPa, 60 MPa, 70 MPa, 75 MPa, 78 MPa, and 80 MPa. Controlling the exfoliation pressure within this range generates shear forces to disrupt the van der Waals forces between graphene sheets, breaking down the inherent agglomerates of graphene and facilitating the further exfoliation of edge-hydroxyl graphene into thinner sheets. Pressure within this range overcomes the resistance of high-viscosity fluids, achieving uniform mixing and dispersion, promoting the interaction between the edge hydroxyl groups of graphene and the polyether polyol molecular chains, enhancing interfacial bonding, and reducing interfacial thermal resistance. Preferably, the exfoliation pressure is 60-80 MPa.

[0051] Specifically, the exfoliation treatment time is 30-90 minutes; understandably, the exfoliation treatment time can be any value within 30-90 minutes; exemplary exfoliation treatment times are 30 minutes, 35 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 85 minutes, 90 minutes, etc. Ensuring that the high-viscosity mixture undergoes sufficient cycling and energy accumulation under high-pressure shearing to achieve a stable and uniform dispersion state helps the hydroxyl groups at the graphene edges form stable hydrogen bonds with the polyether polyol molecular chains, avoiding secondary agglomeration during subsequent storage or processing. Preferably, the exfoliation treatment time is 30-60 minutes. Polyether polyols have high viscosity, and graphene materials are prone to agglomeration; controlling the exfoliation treatment time within the above range is beneficial for achieving nanoscale dispersion and sheet exfoliation.

[0052] Understandably, the pressure and time of the stripping process can be adjusted in a coordinated manner according to the actual application.

[0053] Based on the above preparation method, the oxidant can capture electrons from the edge carbons of graphene under mechanical force, introducing hydroxyl functional groups at the edge of the graphene sheets. This improves the compatibility between graphene and polymer materials during subsequent exfoliation, while maintaining the complete π-π conjugated structure in the middle of the graphene, which is beneficial for the transport of electrons and phonons. This gives the thermally conductive agent high thermal conductivity, high carrier mobility, and excellent mechanical strength. Then, the edge-hydroxylated graphene is exfoliated in situ in the polymer material through the exfoliation process. The hydroxyl groups can form strong interactions such as hydrogen bonds with the polymer chains, strengthening the interfacial adhesion.

[0054] This application also provides a thermal conductive agent prepared using any of the preparation methods described in the above embodiments.

[0055] Specifically, the thermal conductive agents include edge-hydroxylated graphene and polyether polyols.

[0056] This application also provides an elastomer, which includes an elastic material and a thermally conductive agent prepared by any of the preparation methods described in the above embodiments.

[0057] Specifically, the mass ratio of thermal conductive agent to elastic material in the elastomer can be (1-3):(99-97). Understandably, this ratio can be any value within the range of (1-3):(99-97). For example, the mass ratio can be 1:99, 2:99, 1:98, 2:98, 3:97, etc. The thermal conductivity of the elastomer can be 0.1179-0.1363 W / (m·K). Understandably, adding a small amount of thermal conductive agent to the elastic material can yield an elastomer with good thermal conductivity while avoiding affecting its mechanical and elastic properties. Preferably, the mass ratio of thermal conductive agent to elastic material in the elastomer can be 3:97.

[0058] Specifically, during the preparation of elastomers, the hydroxyl groups in the thermal conductive agent can form urethane bonds with the isocyanate groups, which improves the dispersion uniformity and stability of the thermal conductive agent, and is beneficial to improving the thermal conductivity and heat resistance of the elastomer.

[0059] In a possible implementation, the elastic material can be polyurethane.

[0060] The thermal conductive agent provided in this application is in a viscous liquid state. Compared with powdered thermal conductive fillers, the thermal conductive agent provided in this application is easier to mix with elastic materials, avoiding the impact on the mechanical properties of the elastomer due to uneven powder dispersion.

[0061] The following describes specific embodiments of this application in conjunction with the aforementioned thermal conductive agents, their preparation methods, and elastomers. The following embodiments describe the technical solutions of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. The reagents used in the embodiments are commercially available or synthesized using conventional methods and can be used directly without further processing. Similarly, the instruments and apparatus used in the embodiments are commercially available.

[0062] Example 1 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The preparation method of the thermal conductive agent specifically includes the following steps: 1. Provides multilayer graphene materials, potassium persulfate, and polyether polyols; 2. Potassium persulfate and multilayer graphene material in a mass ratio of 70:30 are mixed to obtain a mixture; 3. Place the mixture in a planetary ball mill for ball milling. The ball-to-material ratio is 40:1, the ball milling speed is 350 rpm, and the ball milling time is 120 min. 4. After ball milling, the mixture after ball milling is washed with deionized water to remove excess potassium persulfate, and then dried to obtain edge-hydroxylated graphene. 5. After mixing edge-hydroxylated graphene and polyether polyol at a mass ratio of 1:2, place them in a stripping device for stripping treatment. The stripping treatment pressure is 60 MPa and the stripping treatment time is 30 min to obtain the thermal conductive agent.

[0063] This embodiment also provides an elastomer, comprising an elastic material and a thermally conductive agent prepared in this embodiment, wherein the mass ratio of the elastic material to the thermally conductive agent in the elastomer is 97:3.

[0064] Example 2 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 2 of the preparation method, the mass ratio of potassium persulfate and multilayer graphene in the mixture is 80:20.

[0065] Example 3 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 3 of the preparation method, the ball-to-material ratio of the ball milling process is 50:1.

[0066] Example 4 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 3 of the preparation method, the ball milling speed is 400 rpm.

[0067] Example 5 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 3 of the preparation method, the ball milling time is 90 minutes.

[0068] Example 6 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 5 of the preparation method, the peeling treatment pressure is 80 min and the time is 40 min.

[0069] Example 7 This embodiment provides a thermal conductive agent, its preparation method, and an elastomer. The similarities with Embodiment 1 will not be repeated. The difference from Embodiment 1 is that in step 5 of the preparation method, the peeling treatment pressure is 70 min and the time is 60 min.

[0070] Comparative Example 1 This comparative example provides an elastomer comprising the same elastic material as in Example 1.

[0071] Comparative Example 2 This comparative example provides an elastomer comprising zinc oxide and the same elastic material as in Example 1, wherein the mass ratio of the elastic material to zinc oxide is 10:1.

[0072] The thermal conductivity of the elastomers in Examples 1-7 and Comparative Examples 1-2 was tested, and the test results are shown in Table 1.

[0073] Table 1

[0074] Referring to Table 1, and in conjunction with Examples 1-7 and Comparative Example 1, it can be seen that the content of thermal conductive agent in the elastomer is 3%. When the amount of thermal conductive agent added is low, the thermal conductivity of the elastomer is 0.1193-0.1363 W / (m·K), while the thermal conductivity of the elastomer in Comparative Example 1 without added thermal conductive agent is 0.0907 W / (m·K). Compared with Comparative Example 1, the thermal conductive agent provided in the embodiments of this application can significantly improve the thermal conductivity of the elastomer.

[0075] Based on Examples 1-7 and Comparative Examples 1-2, it can be seen that the content of thermally conductive powder in the elastomer provided in Comparative Example 2 is 10%, and the thermal conductivity of the elastomer in Comparative Example 2 is 0.1025 W / (m·K). It can be seen that the amount of thermally conductive powder added in Comparative Example 2 is relatively high, but the improvement on the thermal conductivity of the elastomer is limited, and it is significantly lower than the thermal conductivity of the elastomer in Examples 1-7 (0.1193-0.1363 W / (m·K). This proves that the thermally conductive agent provided in this application can significantly improve the thermal conductivity of the elastomer with a small amount added. The thermally conductive agent provided in the embodiments of this application has good compatibility with the elastic material and can form an efficient thermal conduction path in the elastomer.

[0076] The foregoing description has fully disclosed the specific embodiments of this application. It should be noted that any modifications made by those skilled in the art to the specific embodiments of this application do not depart from the scope of the claims. Accordingly, the scope of the claims of this application is not limited to the foregoing specific embodiments.

Claims

1. A method for preparing a thermally conductive agent, characterized in that, include: We provide graphene materials, oxidants, and polymer materials. The graphene material and the oxidant are mixed in a certain proportion to obtain a mixture; The mixture was subjected to mechanochemical treatment, washing, and drying to obtain edge-hydroxylated graphene; The edge-hydroxylated graphene is mixed with the polymer material in a certain proportion and then exfoliated to obtain the thermal conductive agent.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the graphene material to the oxidant in the mixture is (3-1):(7-9).

3. The preparation method according to claim 1, characterized in that, The mass ratio of the edge-hydroxylated graphene to the polymer material in the thermal conductive agent is (4-1):(6-19).

4. The preparation method according to any one of claims 1-3, characterized in that, The graphene material satisfies at least one of the following characteristics: The graphene material includes at least one of single-layer graphene, double-layer graphene, few-layer graphene, and multilayer graphene. The graphene material has a sheet diameter of 0.5-50 μm; The graphene material has a carbon content of 95% or greater.

5. The preparation method according to any one of claims 1-3, characterized in that, The oxidant includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, and hypochlorous acid.

6. The preparation method according to any one of claims 1-3, characterized in that, The mechanochemical treatment is a ball milling treatment, and the ball milling treatment satisfies at least one of the following characteristics: The ball-to-material ratio for the ball milling process is (30-50):(1-2); The ball milling process is performed at a speed of 300-400 rpm; The ball milling process takes 60-180 minutes.

7. The preparation method according to any one of claims 1-3, characterized in that, The stripping process satisfies at least one of the following characteristics: The pressure for the stripping process is 50-80 MPa; The stripping process takes 30-90 minutes.

8. The preparation method according to any one of claims 1-3, characterized in that, The polymeric material includes at least polyether polyols.

9. A thermal conductive agent, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. An elastomer, characterized in that, The elastomer comprises an elastic material and a thermally conductive agent prepared by the preparation method as described in any one of claims 1-8.

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