A highly thermally conductive carbon black, its preparation method and application

Abstract

The present invention discloses a highly thermally conductive carbon black and its preparation method and application, relating to the technical field of carbon black modification. The preparation method of the highly thermally conductive carbon black comprises the following steps: performing oxidation treatment, silanization treatment, and tannic acid coating treatment on carbon black to obtain modified carbon black; preparing a graphene / boron nitride / modified carbon black multi-dimensional filler; performing primary modification on the above graphene / boron nitride / modified carbon black multi-dimensional filler with lignin, polyvinylpyrrolidone, and samarium chloride, and then performing secondary modification with 6-aminohexanoic acid to obtain the highly thermally conductive carbon black. The highly thermally conductive carbon black prepared by the present invention not only has good dispersibility, but also can well improve the thermal conductivity and mechanical properties of the rubber matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon black modification, and particularly relates to a highly thermally conductive carbon black and its preparation method and application. Background Art

[0002] Carbon black is an amorphous carbon material formed by the aggregation of nanoscale particles. Its main component is carbon, and it contains a small amount of elements such as oxygen, hydrogen, and sulfur. Its particles are approximately spherical, with a high specific surface area and adsorption capacity, and are widely used in fields such as rubber reinforcing agents, conductive fillers, and inks. Since the interior of carbon black has a disordered or partially ordered microcrystalline structure, heat transfer depends on lattice vibrations. However, pores, impurities, and defects in its structure will hinder the transmission of phonons, and the high surface energy of carbon black particles causes them to easily agglomerate, making it difficult to form a continuous thermal conduction network in the polymer matrix, increasing the interfacial thermal resistance. The above factors result in limited thermal conductivity of carbon black particles, making it difficult to meet the heat dissipation requirements of high-performance materials and restricting its application.

[0003] Currently, the improvement of the thermal conductivity of carbon black mainly includes the following methods: (1) Physical mixing method: Mixing highly thermally conductive materials such as carbon nanotubes and graphene with carbon black to construct a three-dimensional thermal conduction network. For example, the patent with the application number 202411946136.1 discloses a carbon-based enhanced thermally conductive high-viscosity shaped phase change material and its preparation method and application, adding one or more of carbon nanotubes, graphene, carbon black, and carbon fiber as carbon-based thermal conductive particles in a polymer matrix to improve the thermal conductivity of the material; although the above method can improve the thermal conductivity of the material to a certain extent, only using a coupling agent for modification will result in poor bonding between the interfaces of each filler and between the filler and the polymer matrix, thus affecting the mechanical properties of the material. (2) Chemical modification: Converting carbon black into a graphite structure at high temperature to improve crystallinity and thermal conductivity. For example, the patent with the application number 202111243337.1 discloses a method for improving the electrical and thermal conductivity of carbon black. The method is to place a graphite crucible in a closed graphitization furnace; fill the graphite crucible with carbon black and evacuate the air in the graphitization furnace; heat the graphite crucible to 2800 - 3000 °C, keep it warm for 3 - 5 hours, and cool it with the furnace; although the above method can improve the thermal conductivity of carbon black, it requires ultra-high temperature, has strict equipment requirements and huge energy consumption. Moreover, thionyl chloride acylation is used in some chemical modifications, and this process will produce toxic waste liquid and gas. In summary, the modified carbon black in the prior art is difficult to simultaneously meet the multi-functional requirements such as high thermal conductivity and high mechanical strength when added to a polymer matrix. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: In view of the deficiencies in the prior art, to provide a highly thermally conductive carbon black and its preparation method and application, which not only has good dispersibility, but also can well improve the thermal conductivity and mechanical properties of polymer materials.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A preparation method of high thermal conductivity carbon black, comprising the following steps:

[0007] Perform oxidation treatment, silanization treatment, and tannic acid coating treatment on carbon black to obtain modified carbon black;

[0008] Prepare graphene / boron nitride / modified carbon black multi-dimensional filler;

[0009] Perform primary modification on the above graphene / boron nitride / modified carbon black multi-dimensional filler with lignin, polyvinylpyrrolidone, and samarium chloride, and then perform secondary modification with 6-aminocaproic acid to obtain high thermal conductivity carbon black.

[0010] Preferably, the process of the oxidation treatment includes: placing carbon black in concentrated sulfuric acid with a concentration of 3 mol / L, and performing water bath treatment at 65-75 °C for 3-4 h.

[0011] Preferably, the process of the silanization treatment includes: dispersing oxidized carbon black in an ethanol solution, adding polyethylene glycol, mixing evenly, then adding a silane coupling agent, adjusting the pH of the solution to 4-5, and stirring and reacting at 70-80 °C for 10-12 h.

[0012] Preferably, the silane coupling agent is a mixture of γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane, and the mass ratio of the two is 1:1. The addition amount of the silane coupling agent is 10-15 wt% of the mass of oxidized carbon black; the polyethylene glycol is polyethylene glycol 2000, and the addition amount of the polyethylene glycol is 20-30 wt% of the mass of oxidized carbon black.

[0013] Preferably, the process of the tannic acid coating treatment includes: adding tannic acid to a Tris-HCl buffer solution, stirring and mixing, and then adding silanized carbon black and stirring and reacting.

[0014] Preferably, the concentration of the Tris-HCl buffer solution is 10 mmol / L and the pH is 8.5; the mass ratio of tannic acid to silanized carbon black is (0.3-0.5):10; the temperature of the stirring reaction is room temperature, the stirring speed is 500-800 revolutions per minute, and the time is 20-30 h.

[0015] Preferably, the preparation process of the graphene / boron nitride / modified carbon black multi-dimensional filler includes: mixing graphene nanosheets and boron nitride nanosheets and adding them to anhydrous ethanol, ultrasonically dispersing, and then adding modified carbon black and ultrasonically dispersing again.

[0016] Preferably, the mass ratio of graphene nanosheets, boron nitride nanosheets, and modified carbon black is (0.5 - 0.7):(0.3 - 0.4):(2 - 4); the power of ultrasonic dispersion is 300 - 500 W, and the time is 30 - 60 min.

[0017] Preferably, the process of primary modification includes: dispersing the graphene / boron nitride / modified carbon black multi-dimensional filler and polyvinylpyrrolidone in deionized water, then adding lignin and performing ultrasonic treatment to obtain a dispersion; adding a samarium chloride solution to the above dispersion, stirring and mixing, and finally freeze-drying.

[0018] Preferably, the average molecular weight of the polyvinylpyrrolidone is 10,000; the mass ratio of the graphene / boron nitride / modified carbon black multi-dimensional filler, polyvinylpyrrolidone, lignin, and samarium chloride is 1:(0.4 - 1):(0.2 - 0.5):(0.04 - 0.06).

[0019] Preferably, the conditions of the ultrasonic treatment are 500 W and 1 - 2 h; the conditions of the stirring and mixing are: 55 - 60 °C and 3 - 4 h.

[0020] Preferably, the process of secondary modification includes: adding the primary modified filler to a 6 - aminocaproic acid solution, adjusting the pH of the solution to 7 - 8, reacting at 80 °C for 2 - 3 h, cooling to room temperature after the reaction, and ball-milling and centrifuging the reaction solution.

[0021] Preferably, the concentration of the 6 - aminocaproic acid solution is 1 - 3 wt%, and the mass ratio of the primary modified filler to 6 - aminocaproic acid is 1:(0.1 - 0.3).

[0022] The present invention also discloses the application of high - thermal - conductivity carbon black in rubber sealing materials.

[0023] A preparation method of a rubber sealing material includes the following steps:

[0024] I. By weight, add 100 parts of EPDM raw rubber into a mixer, plasticize at 40 °C and 60 r / min for 1 - 2 min, then sequentially add 50 - 80 parts of high - thermal - conductivity carbon black, 5 - 6 parts of zinc oxide, and 1 - 2 parts of stearic acid, plasticize at 125 - 150 °C for 100 - 120 s, add 30 - 50 parts of 68# white oil, and continue mixing for 320 - 340 s;

[0025] II. Add 1.5 - 2 parts of peroxide DCP and 1.0 - 1.5 parts of accelerator CZ to the mixer, lower the mixing temperature to 80 - 85 °C, and mix for 3 - 5 min to obtain a mixed rubber;

[0026] III. Knead the above compounded rubber 15 times at room temperature with the roll gap set to 0.1 mm, and then place it in a flat vulcanizer. Cure it at 150 °C and 10 MPa for 30 min to obtain the rubber sealing material.

[0027] Due to the adoption of the above technical solution, the present invention has at least the following beneficial effects:

[0028] The present invention provides a highly thermally conductive carbon black, which takes carbon black as the core and hybridizes graphene nanosheets and boron nitride nanosheets. During the hybridization process, multi-level modification is carried out, and the obtained highly thermally conductive carbon black has good dispersibility. Specifically in the preparation, the present invention first oxidizes the carbon black to introduce oxygen-containing functional groups such as carboxyl groups and hydroxyl groups on the surface of the carbon black, which is convenient for subsequent modification; the oxidized carbon black is successively subjected to combined modification with polyethylene glycol, γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane, and tannic acid coating. The obtained modified carbon black can not only better combine with the rubber matrix, but also the polyphenol structure of tannic acid can provide rich reaction sites, which is convenient for the interfacial combination of the modified carbon black with graphene nanosheets / boron nitride nanosheets and enhances the interaction between fillers. Graphene nanosheets and boron nitride nanosheets synergistically construct a two-dimensional thermal conduction network, and the modified carbon black acts as a bridge to connect the two, forming a three-dimensional thermal conduction path, reducing the interfacial thermal resistance, and greatly improving the thermal conductivity of the rubber sealing material. In addition, the present invention uses lignin, polyvinylpyrrolidone, samarium chloride and 6-aminohexanoic acid to double-modify the graphene / boron nitride / modified carbon black multi-dimensional filler. Lignin, as a bio-based binder, its polyphenol structure can be hydrogen-bonded with the tannic acid coating layer to enhance the interfacial compatibility between the filler and the rubber matrix; polyvinylpyrrolidone, as a polymer dispersant, winds around the multi-dimensional filler through long chains to further improve its dispersibility; Sm in samarium chloride 3+ Coordinates with the phenolic hydroxyl group of lignin or the carbonyl group of polyvinylpyrrolidone to form a cross-linked network, enhancing the strength of the filler skeleton. During the secondary modification, the carboxyl group in 6-aminohexanoic acid bonds with the hydroxyl group or amino group on the surface of the primary modified filler to form an amide bond or an ionic bond; the amino end participates in the cross-linking reaction during the rubber vulcanization process, enhancing the filler-matrix interfacial bonding.

[0029] The highly thermally conductive carbon black prepared by the present invention is added to the EPDM matrix. After oxidation, silanization and tannic acid coating treatment, the surface functional groups of the carbon black increase, forming covalent bonds or hydrogen bonds with graphene and boron nitride, constructing a three-dimensional interpenetrating thermal conduction network, forming an anisotropic thermal conduction path, significantly reducing the interfacial thermal resistance, and greatly improving the thermal conductivity of the rubber sealing material. After testing, the thermal conductivity of the rubber sealing material prepared by the present invention is 3.5 - 3.9 W / m·k.

[0030] The highly thermally conductive carbon black prepared by the present invention is added to the EPDM matrix. The long-chain molecules of polyvinylpyrrolidone in the highly thermally conductive carbon black are wound around the surface of the filler, absorbing external stress through physical entanglement. At the same time, its pyrrolidone ring forms a π-π conjugation with the EPDM molecular chain, enhancing the tear strength and wear resistance of the rubber sealing material. The carboxyl group of 6-aminocaproic acid undergoes an esterification reaction with the residual hydroxyl groups on the filler surface, and the amino group forms a hydrogen bond with the polar groups in EPDM, forming a "flexible-rigid" gradient interface layer, which can not only buffer stress concentration but also transfer loads through chemical bonds, improving the tensile properties of the rubber sealing material. In addition, the layered structures of boron nitride nanosheets and graphene nanosheets form a transfer film during the friction process, combined with the lubrication of the lignin-samarium coordination network, thereby improving the wear resistance of the rubber sealing material. After testing, the Shore hardness of the rubber sealing material of the embodiment of the present invention is 78-81, the tensile strength is 14.2-15.3 MPa, the tear strength is 51.3-54.0 KN / m, and the DIN abrasion is 27-32 mm 3 。 Detailed implementation manners

[0031] In order to be able to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0032] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0033] In order to further understand the present invention, the preferred implementation schemes of the present invention will be described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention.

[0034] The performance parameters and sources of some raw materials in the following examples and comparative examples are as follows:

[0035] Carbon black: Carbon black N550, Cabot Chemical Co., Ltd.;

[0036] Graphene nanosheets: No. XF021, diameter: 5-10 μm, thickness: 3-10 nm, specific surface area: 31.657 m 2 / g, Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0037] Boron nitride nanosheets: No. XFBN03-1, sheet diameter 0.1-0.4 μm, Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0038] Lignin: average particle size 10 μm, Jining Mingsheng New Materials Co., Ltd.;

[0039] EPDM raw rubber: grade 3110M, SINOPEC Mitsui Chemicals, Inc.

[0040] Other raw materials are ordinary commercially available without special instructions. Other conditions are conventional conditions in this field or conditions that can be achieved by those skilled in the art according to the existing technology without special instructions. Example 1

[0041] A preparation method of high thermal conductivity carbon black, comprising the following steps:

[0042] (1) Place 1 g of carbon black in 50 ml of concentrated sulfuric acid with a concentration of 3 mol / L, perform a water bath treatment at 70 °C for 3 h, filter the treatment solution after the treatment, and dry the precipitate to obtain oxidized carbon black;

[0043] (2) Disperse 5 g of oxidized carbon black in 100 ml of ethanol solution (mass ratio of ethanol to deionized water is 9:1), add polyethylene glycol 2000 (the addition amount is 20 wt% of the mass of oxidized carbon black), mix evenly, then add γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane (mass ratio of γ-mercaptopropyltrimethoxysilane to vinyltrimethoxysilane is 1:1; the total addition amount of γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane is 11 wt% of the mass of oxidized carbon black), adjust the pH of the solution to 4, stir and react at 70 °C for 12 h, cool the reaction solution to room temperature after the reaction and then filter, and dry the precipitate to obtain silanized carbon black;

[0044] (3) Add 0.3 g of tannic acid to 500 ml of Tris-HCl buffer solution (concentration is 10 mmol / L, pH is 8.5), stir and mix at 800 revolutions per minute for 10 min, then add 10 g of silanized carbon black, stir and react at room temperature and 800 revolutions per minute for 24 h, filter the reaction solution after the reaction, and dry the precipitate to obtain modified carbon black;

[0045] (4) Add 0.5 g of graphene nanosheets and 0.3 g of boron nitride nanosheets to 200 ml of absolute ethanol, ultrasonically disperse at 300 W for 60 min, then add 2 g of modified carbon black, ultrasonically disperse again at 500 W for 60 min, then filter the dispersion, disperse 5 g of the filtered precipitate and 2 g of polyvinylpyrrolidone (Mn = 10000) in 500 ml of deionized water, then add 1 g of lignin, ultrasonically treat at 500 W for 1 h to obtain a dispersion; add a 2 wt% samarium chloride solution (the addition amount is 4 wt% of the mass of the filtered precipitate) to the above dispersion, stir and mix at 55 °C and 800 rpm for 3 h, after the reaction, filter the reaction solution and freeze-dry the precipitate to obtain a primary modified filler;

[0046] (5) Add the primary modified filler into 50 ml of 1 wt% 6 - aminocaproic acid solution (control the mass ratio of the primary modified filler to 6 - aminocaproic acid to be 1:0.1), adjust the pH of the solution to 7, react at 80 °C for 2 h, after the reaction, cool to room temperature, ball - mill the reaction solution and then centrifuge it, and dry the centrifuged precipitate to obtain highly thermally conductive carbon black. Example 2

[0047] A preparation method of highly thermally conductive carbon black, comprising the following steps:

[0048] (1) Place 1 g of carbon black in 50 ml of concentrated sulfuric acid with a concentration of 3 mol / L, perform a water - bath treatment at 70 °C for 3.5 h, after the treatment, filter the treatment solution, dry the precipitate to obtain oxidized carbon black;

[0049] (2) Disperse 5 g of oxidized carbon black in 100 ml of ethanol solution (the mass ratio of ethanol to deionized water is 9:1), add polyethylene glycol 2000 (the addition amount is 25 wt% of the mass of oxidized carbon black), after mixing evenly, then add γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane (the mass ratio of γ - mercaptopropyltrimethoxysilane to vinyltrimethoxysilane is 1:1; the total addition amount of γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane is 13 wt% of the mass of oxidized carbon black), adjust the pH of the solution to 5, stir and react at 75 °C for 10 h, after the reaction, cool the reaction solution to room temperature and then filter it, dry the precipitate to obtain silanized carbon black;

[0050] (3) Add 0.4 g of tannic acid into 500 ml of Tris - HCl buffer solution (concentration is 10 mmol / L, pH is 8.5), stir and mix at a speed of 700 revolutions per minute for 10 min, then add 10 g of silanized carbon black, stir and react at room temperature and 800 revolutions per minute for 24 h, after the reaction, filter the reaction solution, dry the precipitate to obtain modified carbon black;

[0051] (4) Add 0.6 g of graphene nanosheets and 0.35 g of boron nitride nanosheets into 200 ml of absolute ethanol, ultrasonically disperse at 500 W for 40 min, then add 3 g of modified carbon black, ultrasonically disperse again at 400 W for 50 min, then filter the dispersion liquid, disperse 5 g of the filtered precipitate and 3 g of polyvinylpyrrolidone (Mn = 10000) in 500 ml of deionized water, then add 1.5 g of lignin, ultrasonically treat at 500 W for 1.5 h to obtain a dispersion liquid; add a 2 wt% samarium chloride solution (the addition amount is 5 wt% of the mass of the filtered precipitate) into the above - mentioned dispersion liquid, stir and mix at 55 °C and 600 rpm for 3.5 h, after the reaction, filter the reaction solution and freeze - dry the precipitate to obtain the primary modified filler;

[0052] (5) Add the primary modified filler to 50 ml of a 2 wt% 6 - aminocaproic acid solution (control the mass ratio of the primary modified filler to 6 - aminocaproic acid to be 1:0.2), adjust the pH of the solution to 8, react at 80 °C for 2.5 h, cool to room temperature after the reaction, ball - mill the reaction solution and then centrifuge it. Dry the centrifuged precipitate to obtain highly thermally conductive carbon black. Example 3

[0053] A method for preparing highly thermally conductive carbon black, comprising the following steps:

[0054] (1) Place 1 g of carbon black in 50 ml of concentrated sulfuric acid with a concentration of 3 mol / L, perform a water - bath treatment at 70 °C for 4 h. After the treatment, filter the treatment solution, dry the precipitate to obtain oxidized carbon black;

[0055] (2) Disperse 5 g of oxidized carbon black in 100 ml of an ethanol solution (the mass ratio of ethanol to deionized water is 9:1), add polyethylene glycol 2000 (the addition amount is 28 wt% of the mass of oxidized carbon black). After mixing evenly, add γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane (the mass ratio of γ - mercaptopropyltrimethoxysilane to vinyltrimethoxysilane is 1:1; the total addition amount of γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane is 14 wt% of the mass of oxidized carbon black), adjust the pH of the solution to 5, stir and react at 75 °C for 12 h. After the reaction, cool the reaction solution to room temperature and then filter it. Dry the precipitate to obtain silanized carbon black;

[0056] (3) Add 0.4 g of tannic acid to 500 ml of Tris - HCl buffer solution (concentration is 10 mmol / L, pH is 8.5), stir and mix at 800 revolutions per minute for 10 min, then add 10 g of silanized carbon black, stir and react at room temperature and 600 revolutions per minute for 24 h. After the reaction, filter the reaction solution, dry the precipitate to obtain modified carbon black;

[0057] (4) Add 0.6 g of graphene nanosheets and 0.35 g of boron nitride nanosheets to 200 ml of anhydrous ethanol, ultrasonically disperse at 500 W for 60 min, then add 3.5 g of modified carbon black, ultrasonically disperse again at 500 W for 50 min. After that, filter the dispersion. Disperse 5 g of the filtered precipitate and 4 g of polyvinylpyrrolidone (Mn = **********) in 500 ml of deionized water, then add 2 g of lignin, and ultrasonically treat at 500 W for 1 h to obtain a dispersion. Add a 2 wt% samarium chloride solution (the addition amount is 4 - 6 wt% of the mass of the filtered precipitate) to the above dispersion, stir and mix at 60 °C and 800 rpm for 3 h. After the reaction, filter the reaction solution and freeze - dry the precipitate to obtain the primary modified filler;

[0058] (5) Add the primary modified filler to 50 ml of a 2.5 wt% 6 - aminocaproic acid solution (control the mass ratio of the primary modified filler to 6 - aminocaproic acid to be 1:0.25), adjust the pH of the solution to 7, react at 80 °C for 2.5 h, cool to room temperature after the reaction, ball - mill the reaction solution and then centrifuge, and dry the centrifuged precipitate to obtain highly thermally conductive carbon black. Example 4

[0059] A preparation method of highly thermally conductive carbon black, comprising the following steps:

[0060] (1) Place 1 g of carbon black in 50 ml of concentrated sulfuric acid with a concentration of 3 mol / L, perform a water - bath treatment at 70 °C for 3.5 h, filter the treatment solution after the treatment, and dry the precipitate to obtain oxidized carbon black;

[0061] (2) Disperse 5 g of oxidized carbon black in 100 ml of an ethanol solution (the mass ratio of ethanol to deionized water is 9:1), add polyethylene glycol 2000 (the addition amount is 30 wt% of the mass of oxidized carbon black), after mixing evenly, then add γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane (the mass ratio of γ - mercaptopropyltrimethoxysilane to vinyltrimethoxysilane is 1:1; the total addition amount of γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane is 15 wt% of the mass of oxidized carbon black), adjust the pH of the solution to 5, stir and react at 75 °C for 11 h, cool the reaction solution to room temperature after the reaction and then filter, and dry the precipitate to obtain silanized carbon black;

[0062] (3) Add 0.5 g of tannic acid to 500 ml of Tris - HCl buffer solution (concentration is 10 mmol / L, pH is 8.5), stir and mix at 700 revolutions per minute for 10 min, then add 10 g of silanized carbon black, stir and react at room temperature and 700 revolutions per minute for 24 h, filter the reaction solution after the reaction, and dry the precipitate to obtain modified carbon black;

[0063] (4) Add 0.65 g of graphene nanosheets and 0.35 g of boron nitride nanosheets to 200 ml of anhydrous ethanol, ultrasonically disperse at 500 W for 50 min, then add 3.5 g of modified carbon black, ultrasonically disperse again at 500 W for 60 min, then filter the dispersion, disperse 5 g of the filtered precipitate and 4.5 g of polyvinylpyrrolidone (Mn = 10000) in 500 ml of deionized water, then add 2.5 g of lignin, and ultrasonically treat at 500 W for 1.5 h to obtain a dispersion; add a 2 wt% samarium chloride solution (the addition amount is 5 wt% of the mass of the filtered precipitate) to the above - mentioned dispersion, stir and mix at 55 °C and 700 rpm for 4 h, after the reaction, filter the reaction solution and freeze - dry the precipitate to obtain the primary modified filler;

[0064] (5) Add the once-modified filler into 50 ml of 3 wt% 6 - aminocaproic acid solution (control the mass ratio of the once-modified filler to 6 - aminocaproic acid as 1:0.3), adjust the pH of the solution to 7, react at 80 °C for 3 h, cool to room temperature after the reaction, ball-mill the reaction solution and then centrifuge it. Dry the centrifugal precipitate to obtain highly thermally conductive carbon black.

[0065] Comparative Example 1

[0066] Do not include step (2), and other operations are the same as those in Example 4.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 4 is that in step (2), polyethylene glycol 2000 is not added, and other operations are the same as those in Example 4.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 4 is that in step (2), γ - mercaptopropyltrimethoxysilane and vinyltrimethoxysilane are not added, and other operations are the same as those in Example 4.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 4 is that in step (2), an equal amount of γ - mercaptopropyltrimethoxysilane is used to replace vinyltrimethoxysilane, and other operations are the same as those in Example 4.

[0073] Comparative Example 5

[0074] The difference between this comparative example and Example 4 is that in step (2), an equal amount of vinyltrimethoxysilane is used to replace γ - mercaptopropyltrimethoxysilane, and other operations are the same as those in Example 4.

[0075] Comparative Example 6

[0076] The difference between this comparative example and Example 4 is that step (3) is not included, and other operations are the same as those in Example 4.

[0077] Comparative Example 7

[0078] The difference between this comparative example and Example 4 is that in step (4), an equal amount of boron nitride nanosheets is used to replace graphene nanosheets, and other operations are the same as those in Example 4.

[0079] Comparative Example 8

[0080] The difference between this comparative example and Example 4 is that in step (4), an equal amount of graphene nanosheets is used to replace boron nitride nanosheets, and other operations are the same as those in Example 4.

[0081] Comparative Example 9

[0082] The difference between this comparative example and Example 4 is that in step (4), polyvinylpyrrolidone (Mn = 10000) is not added, and other operations are the same as those in Example 4.

[0083] Comparative Example 10

[0084] The difference between this comparative example and Example 4 is that in step (4), lignin is not added, and other operations are the same as those in Example 4.

[0085] Comparative Example 11

[0086] The difference between this comparative example and Example 4 is that in step (4), samarium chloride is not added, and other operations are the same as those in Example 4.

[0087] Comparative Example 12

[0088] The difference between this comparative example and Example 4 is that step (5) is not included, and other operations are the same as those in Example 4.

[0089] Test Example 1:

[0090] 1 g of the fillers of the above Examples 1-4 and Comparative Examples 1-12 were respectively mixed with 50 ml of absolute ethanol and ultrasonically dispersed for 30 min at a power of 500 W to obtain different dispersions; the above dispersions were placed at room temperature for 180 days, and the state of the dispersions was observed every day during this period, and whether there was precipitation was observed by visual inspection. The test results are shown in Table 1.

[0091] Table 1

[0092]

[0093] It can be seen from the test results in Table 1 that compared with the comparative examples, the carbon black prepared in the examples of the present invention has good dispersibility in absolute ethanol.

[0094] The carbon black in Comparative Example 1 is not silanized, and there are not enough functional groups on the surface of the carbon black to maintain dispersion, and it cannot be well combined with graphene nanosheets and boron nitride nanosheets, resulting in poor dispersion stability. Polyethylene glycol is used as a dispersant to help the particles disperse. In Comparative Example 2, polyethylene glycol is not added, resulting in a certain impact on its dispersion effect. Silanization treatment is to increase the compatibility of carbon black with other materials for subsequent modification. In Comparative Example 3, the carbon black is not silanized, resulting in poor tannic acid coating effect and affecting the dispersion of the final filler.

[0095] When silanizing carbon black, two different types of silane coupling agents are used, which can increase the crosslinking degree, thereby better improving the dispersion of carbon black. In Comparative Examples 4 and 5, only a single silane coupling agent is used, and the effect is poor, resulting in worse dispersion than Example 3.

[0096] The coating of tannic acid can further modify the surface of carbon black, increase the combination of carbon black with other materials, and further improve the dispersion of the final high thermal conductivity carbon black. In Comparative Example 6, tannic acid coating was not used, resulting in a significant decrease in the dispersion of the prepared high thermal conductivity carbon black.

[0097] In Comparative Example 7 and Comparative Example 8, boron nitride nanosheets or graphene nanosheets were used alone, and the dispersion of the prepared high thermal conductivity carbon black decreased. Because boron nitride nanosheets and graphene nanosheets have a two-dimensional sheet structure, which can form a physical barrier when dispersed in the carbon black system and can inhibit the aggregation of carbon black particles to a certain extent. In addition, the high specific surface area and mechanical strength of graphene can support the dispersion of carbon black particles and prevent sedimentation.

[0098] In Comparative Example 9 and Comparative Example 10, without adding polyvinylpyrrolidone or lignin, the high thermal conductivity carbon black could not be well dispersed. Because lignin and polyvinylpyrrolidone, as compound dispersants, inhibit the agglomeration of fillers through the dual mechanisms of steric hindrance and electrostatic repulsion.

[0099] Samarium chloride can enhance the interfacial bonding between the filler and the matrix through coordination. In Comparative Example 11, without adding samarium chloride, the dispersion of the prepared high thermal conductivity carbon black decreased significantly.

[0100] The carboxyl group and amino group of 6-aminohexanoic acid form an amphoteric ion structure, which can introduce active sites on the surface of the filler and increase the interfacial bonding between the high thermal conductivity carbon black and the matrix. In Comparative Example 12, the treatment with 6-aminohexanoic acid was omitted, which affected the dispersion of the high thermal conductivity carbon black.

[0101] To better illustrate the application of high thermal conductivity carbon black in rubber sealing materials, multiple application examples are described below.

[0102] Application Example 1

[0103] The preparation in the rubber sealing material includes the following steps:

[0104] S1: By weight, 100 parts of EPDM raw rubber are added to a kneader, plasticized at 40 °C and 60 r / min for 2 min, then 75 parts of the high thermal conductivity carbon black of Example 1, 5 parts of zinc oxide, and 1 part of stearic acid are added in sequence, kneaded at 1130 °C for 120 s, and after adding 45 parts of 68# white oil, kneading is continued for 340 s;

[0105] S2: 1.8 parts of peroxide (DCP) and 1.3 parts of accelerator CZ are added to the kneader, the kneading temperature is lowered to 82 °C, and kneading is carried out for 35 min to obtain a kneaded rubber;

[0106] S3: Knead the above - mentioned rubber compound 15 times at room temperature with the roll gap set to 0.1 mm, then place it in a flat vulcanizer and vulcanize it at 150 °C and 10 MPa for 30 min to obtain a rubber sealing material.

[0107] Application Example 2

[0108] The difference between this example and Application Example 1 is that: an equal amount of the highly thermally conductive carbon black of Example 2 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0109] Application Example 3

[0110] The difference between this example and Application Example 1 is that: an equal amount of the highly thermally conductive carbon black of Example 3 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0111] Application Example 4

[0112] The difference between this example and Application Example 1 is that: an equal amount of the highly thermally conductive carbon black of Example 4 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0113] Application Comparative Example 1

[0114] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 1 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0115] Application Comparative Example 2

[0116] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 2 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0117] Application Comparative Example 3

[0118] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 3 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0119] Application Comparative Example 4

[0120] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 4 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0121] Application Comparative Example 5

[0122] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 5 is used to replace the highly thermally conductive carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0123] Application Comparative Example 6

[0124] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 6 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0125] Application Comparative Example 7

[0126] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 7 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0127] Application Comparative Example 8

[0128] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 8 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0129] Application Comparative Example 9

[0130] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 9 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0131] Application Comparative Example 10

[0132] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 10 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0133] Application Comparative Example 11

[0134] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 11 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0135] Application Comparative Example 12

[0136] The difference between this example and Application Example 1 is that: an equal amount of the carbon black of Comparative Example 12 is used to replace the high thermal conductivity carbon black of Example 1, and other operations are the same as those in Application Example 1.

[0137] Test Example 2:

[0138] Perform performance tests on the rubber sealing materials prepared in the above Application Examples and Application Comparative Examples. The test methods and test results are as follows:

[0139] 1. Shore A hardness:

[0140] Test according to GB 531-1983.

[0141] 2. Tensile strength:

[0142] Test according to GB / T 528-2009.

[0143] 3. Tear strength:

[0144] Test according to GB / T 529-2008.

[0145] 4. DIN abrasion performance:

[0146] Test according to GB / T 9867-2008.

[0147] 5. Thermal conductivity:

[0148] The thermal conductivity of the sample was measured using a Hot Disk (TPS2005s) thermal constant analyzer. The single-sided method was used, and the sample thickness was 6 mm.

[0149] The test results are shown in Table 2.

[0150] Table 2

[0151]

[0152] It can be seen from the test results in Table 2 that compared with the comparative example, in the embodiment of the present invention, a three-dimensional thermal conduction network with carbon black as the core was prepared through multi-stage chemical modification, which can be evenly dispersed in rubber, and the prepared rubber sealing material has good mechanical properties and thermal conductivity.

[0153] Compared with the embodiment, the high thermal conductivity carbon black in Comparative Example 1 was not silanized, and the surface active groups of the carbon black were insufficient, resulting in poor interfacial bonding force with the rubber matrix and serious agglomeration in the matrix, resulting in a significant decrease in the Shore A hardness, tensile strength, and thermal conductivity of the material.

[0154] When the high thermal conductivity filler used in Comparative Example 2 was prepared, polyethylene glycol 2000 was not added during the silanization treatment of carbon black, resulting in easy agglomeration of carbon black during silanization treatment, forming nano-level aggregates. The aggregated carbon black particles could not be fully grafted with the silane coupling agent, thereby reducing the chemical bonding sites between the high thermal conductivity carbon black filler and the rubber matrix and affecting the performance of the rubber sealing material.

[0155] The high thermal conductivity filler used in Comparative Example 3 did not add a silane coupling agent, resulting in weak bonding force between the carbon black and the rubber matrix and a significant decrease in the performance of the prepared rubber sealing material.

[0156] In Comparative Application Example 4 and Comparative Application Example 5, the carbon black was treated with a single silane coupling agent, and the properties of the prepared material decreased to a certain extent. Since γ-mercaptopropyltrimethoxysilane can provide mercapto groups to enhance the chemical bonding between the highly thermally conductive carbon black and the rubber matrix, and vinyltrimethoxysilane can enhance physical entanglement, the two work together to effectively increase the interfacial bonding between the highly thermally conductive carbon black and the rubber matrix.

[0157] In Comparative Application Example 6, the carbon black was not coated with tannic acid, and the wear resistance and tear resistance of the prepared rubber sealing material decreased significantly. Because the polyphenol structure in tannic acid molecules can form a flexible interfacial layer and a lubricating layer on the surface of carbon black, enhancing the physical entanglement between carbon black and rubber chains, reducing frictional loss, and tannic acid forms a lubricating layer; moreover, the hydroxyl groups of tannic acid can undergo a condensation reaction with the methoxy groups of the silane coupling agent to form stable Si-O-C bonds; when the coating of tannic acid is missing, the interfacial bonding between carbon black and the rubber matrix is poor.

[0158] In Comparative Application Example 7 and Comparative Application Example 8, only graphene nanosheets or boron nitride nanosheets were used, and the thermal conductivity of the prepared rubber sealing material decreased significantly. Because the combination of graphene nanosheets and boron nitride nanosheets can construct a multi-dimensional heat conduction path in the rubber matrix, thus better improving the thermal conductivity of the rubber sealing material.

[0159] In the preparation of the highly thermally conductive carbon black in Comparative Application Example 9, polyvinylpyrrolidone was not added, and in the preparation of the highly thermally conductive carbon black in Comparative Application Example 10, lignin was not added, and the mechanical properties and thermal conductivity of the prepared rubber sealing material decreased significantly. Because of the lack of the synergistic dispersion of polyvinylpyrrolidone and lignin, the prepared highly thermally conductive carbon black has poor dispersion in the rubber matrix, the stress transfer efficiency is reduced, and the interfacial thermal resistance increases.

[0160] In the preparation of the highly thermally conductive carbon black in Comparative Application Example 11, samarium chloride was not added, and the thermal conductivity of the rubber sealing material decreased. Because samarium chloride can enhance the interfacial bonding between the filler and the matrix through coordination, so that the highly thermally conductive carbon black forms a good continuous heat conduction path in the rubber matrix, thereby improving the heat conduction efficiency.

[0161] In the preparation of the highly thermally conductive carbon black in Comparative Application Example 12, 6-aminocaproic acid was not used for modification, and the properties of the prepared rubber sealing material decreased to a certain extent. Because the amino group in the 6-aminocaproic acid molecule can form a covalent bond with the carboxyl group or epoxy group remaining on the surface of the carbon black silane coupling agent, and at the same time, the carboxyl end of the 6-aminocaproic acid molecule can undergo a chemical reaction with the rubber matrix, thus achieving better dispersion; moreover, the flexible carbon chain of 6-aminocaproic acid can form a buffer layer to absorb the thermal stress generated during the vulcanization process, thereby improving the mechanical properties of the rubber sealing material.

[0162] In this article, specific examples are used to elaborate on the principles and implementation modes of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that have no substantial difference from the literal expression of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A preparation method of high thermal conductivity carbon black, characterized in that, The following steps are involved: The carbon black is subjected to oxidation treatment, silanization treatment, and tannic acid coating treatment to obtain modified carbon black; Preparation of graphene / boron nitride / modified carbon black multidimensional filler; the mass ratio of graphene nanosheets, boron nitride nanosheets, and modified carbon black is (0.5-0.7): (0.3-0.4): (2-4); The graphene / boron nitride / modified carbon black multidimensional filler is modified once with lignin, polyvinyl pyrrolidone, and samarium chloride, and then modified twice with 6-aminocaproic acid to obtain high thermal conductivity carbon black; The silanization process includes: dispersing oxidized carbon black in an ethanol solution, adding polyethylene glycol, mixing uniformly, adding a silane coupling agent, adjusting the pH of the solution to 4-5, and stirring the reaction at 70-80° C. for 10-12 hours; The silane coupling agent is a mixture of γ-mercaptopropyltrimethoxysilane and vinyltrimethoxysilane, with a mass ratio of 1:

1. The added amount of the silane coupling agent is 10-15wt% of the mass of the oxidized carbon black; the polyethylene glycol is polyethylene glycol 2000, and the added amount of the polyethylene glycol is 20-30wt% of the mass of the oxidized carbon black.

2. The preparation method of a highly thermally conductive carbon black according to claim 1, wherein: The oxidation treatment process includes: placing the carbon black in concentrated sulfuric acid with a concentration of 3 mol / L, and treating it in a water bath at 65-75° C. for 3-4 hours.

3. The preparation method of a highly thermally conductive carbon black according to claim 1, characterized in that: The tannic acid coating treatment process includes: adding tannic acid to a Tris-HCl buffer solution, stirring and mixing, then adding silanized carbon black, and stirring and reacting; The concentration of the Tris-HCl buffer solution is 10 mmol / L, and the pH is 8.5; the mass ratio of tannic acid to silanized carbon black is (0.3-0.5):10; the stirring reaction temperature is room temperature, the stirring speed is 500-800 rpm, and the time is 20-30 hours.

4. The preparation method of a highly thermally conductive carbon black according to claim 1, characterized in that: The preparation process of the graphene / boron nitride / modified carbon black multidimensional filler comprises: mixing graphene nanosheets and boron nitride nanosheets, adding them into anhydrous ethanol, ultrasonically dispersing them, then adding modified carbon black, and ultrasonically dispersing them again; The power of ultrasonic dispersion is 300-500W, and the time is 30-60min.

5. The preparation method of a highly thermally conductive carbon black according to claim 1, characterized in that: The primary modification process includes: dispersing graphene / boron nitride / modified carbon black multidimensional filler and polyvinyl pyrrolidone in deionized water, then adding lignin, and ultrasonically treating to obtain a dispersion; adding samarium chloride solution to the dispersion, stirring and mixing, and finally freeze-drying.

6. The preparation method of a highly thermally conductive carbon black according to claim 5, characterized in that: The average molecular weight of the polyvinyl pyrrolidone is 10,000; the mass ratio of the graphene / boron nitride / modified carbon black multidimensional filler, polyvinyl pyrrolidone, lignin, and samarium chloride is 1:(0.4-1):(0.2-0.5):(0.04-0.06); The ultrasonic treatment conditions are 500W, 1-2h; the stirring and mixing conditions are: 55-60°C, 3-4h.

7. The preparation method of a highly thermally conductive carbon black according to claim 1, wherein: The secondary modification process includes: adding the primary modified filler to a 6-aminocaproic acid solution, adjusting the pH of the solution to 7-8, reacting at 80°C for 2-3 hours, cooling to room temperature after the reaction, ball milling the reaction solution, and then centrifuging; The concentration of the 6-aminocaproic acid solution is 1-3 wt%, and the mass ratio of the primary modified filler to 6-aminocaproic acid is 1:(0.1-0.3).

8. A highly thermally conductive carbon black, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. Application of the highly thermally conductive carbon black according to claim 8 in a rubber sealing material.

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