Graphene filler and preparation method thereof

Abstract

The invention discloses a graphene filler and a preparation method thereof, and belongs to the technical field of graphene. According to the preparation method disclosed by the invention, the graphene film is subjected to surface modification, then the modified graphene prefabricated filler is obtained through one-time stripping, and finally the final graphene filler is obtained through separation and collection. Compared with the prior art, the method is simple and easy to operate, does not need high-precision equipment, and is rapid in preparation process and low in cost of required raw materials; large-scale production can be achieved, and the technical problem that an existing preparation method is complex in production process is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of graphene, and particularly relates to a graphene filler and a preparation method thereof. Background Art

[0002] Graphene is a two-dimensional material formed by arranging single-layer carbon atoms in a hexagonal lattice. Since it was discovered by two scientists, Andre Geim and Konstantin Novoselov, from the University of Manchester, UK in 2004, graphene has quickly become a global research and industrial hotspot due to its excellent electrical conductivity, thermal conductivity, mechanical strength, and chemical stability. The internal carrier mobility of graphene is extremely high, reaching 2×10 5 cm 2 / Ns, which is 140 times that of the electron mobility in silicon. At the same time, its thermal conductivity is also extremely high, with a theoretical thermal conductivity of 5300 W / mK, making it the best heat-conducting material at room temperature. In addition, the light absorption rate of single-layer graphene is only 2.3%, and it is effective for any wavelength, breaking the absorption limit of traditional semiconductor materials.

[0003] These excellent properties make graphene an ideal filler material in many fields. Application in anticorrosive coatings: Graphene has extremely high surface energy and strong hydrophobic effects. Its surface has a natural resistance to the growth and adhesion of microorganisms. Graphene grown by chemical vapor deposition (CVD) technology can build an effective protective layer on the metal surface, effectively preventing metal oxidation and corrosion. Conductive coatings: Graphene has better electrical conductivity and good mechanical properties. Moreover, graphene has a large specific surface area and a low conductive percolation threshold, and only a small addition amount is required to achieve the purpose of conductivity. Thermal management materials: The high thermal conductivity of graphene makes it an ideal choice for thermal management materials. High thermal conductivity plastics filled with graphene can meet the requirements of the development of high-density and high-integration assembly in the electronics industry. For example, adding graphene to polyamide (PA) can significantly improve the thermal conductivity of the material. Composites: Graphene can be compounded with matrix materials such as polymers, metals, and ceramics to prepare composites with excellent mechanical and electrical properties. These composites have broad application prospects in the fields of aerospace, automotive, and electronics.

[0004] At present, the large-scale preparation technology of graphene films has been relatively mature, and the market competition is fierce. Further deep processing of graphene films to broaden their market, improve the added value of products, and further adapt to downstream applications has become a research hotspot in the graphene heat dissipation film industry. Among them, using the intermediate product of graphene heat dissipation films as a filler to fuse with matrix materials with other excellent properties such as polymers and metals to prepare functional materials and composites is an important way to broaden the application of graphene films.

[0005] The Chinese patent application with the publication number CN117568953A discloses a graphene fiber, a graphene fiber bundle and a preparation method thereof. Using a polyacrylonitrile solution as a spinning solution and a graphene oxide solution as a collecting bath, electrospinning is carried out to obtain a graphene oxide composite fiber; the graphene oxide composite fiber is successively subjected to pre-oxidation treatment, carbonization treatment and graphitization treatment to obtain the graphene fiber bundle. The Chinese patent application with the publication number CN101830459A discloses a method for preparing dry graphene powder by using freeze-drying technology. The graphene suspension dispersed in a solvent is subjected to freeze-drying treatment to obtain dry graphene powder. Compared with the graphene powder obtained by methods such as filtration, the graphene powder prepared by this method is more likely to be exfoliated into single-layer or multi-layer graphene sheets in some organic solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), acetone, toluene or a mixed solvent of organic solvents.

[0006] Electrospinning and freeze-drying technology for preparing graphene fillers are currently common manufacturing technologies, but there are still some disadvantages. First, the electrospinning technology has a high cost. The manufacturing process of graphene fillers requires special equipment and technology and is carried out under conditions such as high temperature and high pressure, which results in a high manufacturing cost of graphene. At the same time, in order to ensure the uniform dispersion of graphene in the spinning solution and the spinning effect, it may be necessary to configure high-precision equipment such as a spin coater pump, further increasing the manufacturing cost. Second, the electrospinning process is difficult. The chemical properties of graphene are stable and the binding force between molecules is strong. During the electrospinning process, parameters such as the composition of the spinning solution, the spinning voltage, and the receiving distance need to be precisely controlled to obtain an ideal graphene fiber structure and performance. Moreover, the binding force between graphene molecules is weak and it is easy to occur delamination, thus affecting the strength and durability of the material. During the long-term use of electrospun graphene fibers, the performance may decline due to fatigue. At present, electrospun graphene fibers are mainly applied in some high-end fields such as fuel cells, gas purification, high-temperature purification, and nanocatalysis, and their applications in ordinary textiles, daily necessities and other fields are relatively few.

[0007] Although freeze-dried graphene powder has many advantages, such as protecting the microstructure and performance, avoiding agglomeration, simple and safe operation, and suitable for large-scale production, there are also some disadvantages. The freeze-drying process requires a large amount of refrigerant and energy to maintain a low-temperature environment and a vacuum state, which also increases the operating cost. Long time cycle: The freeze-drying process includes multiple stages such as pre-freezing, sublimation drying and desorption drying, and each stage requires a certain amount of time to complete. Especially for large-scale production, the entire freeze-drying cycle may be longer, affecting the production efficiency. It is urgent to find an efficient and fast method for preparing graphene fillers. Summary of the Invention

[0008] The object of the present invention is to provide a graphene filler and a preparation method thereof, so as to solve the technical problems of high energy consumption, high cost, long manufacturing cycle and high processing difficulty in the existing preparation methods, resulting in complex processes. In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a preparation method of a graphene filler, comprising the following steps: Mix and modify the graphene film with a surface modifier to obtain a modified graphene film premix; Subject the modified graphene film premix to primary delamination to obtain a modified graphene prefabricated filler; Separate and collect the modified graphene prefabricated filler by using a separation device to obtain the graphene filler.

[0009] Further, the preparation method of the graphene film is as follows: Coat and dry the graphene oxide slurry to obtain a graphene oxide film; subsequently, subject the graphene oxide film to heat treatment to obtain the graphene film.

[0010] Further, the solid content of the graphene oxide slurry is 0.5% - 10%, and the viscosity is 5000 - 250000 mPas; The water content of the graphene oxide film is 10% - 40%; the coating thickness of the coating and drying treatment is 0.5 - 20 mm.

[0011] Further, the process parameters of the heat treatment are as follows: when the heat treatment temperature is less than 85°C, the weight loss ratio of the product is 0.4 - 5% / h; when the heat treatment temperature is 85 - 145°C, the weight loss ratio of the product is 0.04 - 2.5% / h; when the heat treatment temperature is 145 - 300°C, the weight loss ratio of the product is 0.005 - 1.5% / h; when the heat treatment temperature is 300 - 1100°C, the heat treatment heating rate is 1 - 15°C / min; when the heat treatment temperature is 1100 - 2400°C, the heat treatment heating rate is 0.5 - 10°C / min; the heat treatment cut-off temperature is 2100 - 2400°C; In the heat treatment, the heating atmosphere at 85 - 500°C and 1100°C - the heat treatment cut-off temperature is at least one or a mixture of air, argon, and nitrogen; the 500 - 1100°C stage is vacuum heat treatment, and the vacuum degree is 10 -4 ~10 -6 Torr.

[0012] Further, the surface modifier is one or more of methyl cellulose, sodium carboxymethyl cellulose, aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, triaminopropylmethyldiethoxysilane, and N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane.

[0013] Further, the primary peeling method is refined pre-peeling; the peeling rotation speed of the refined pre-peeling is 2000 - 4000 r / min, and the time is 0.5 - 2 h.

[0014] Further, the separating device is a cotton opener; the process parameters for separation and collection are as follows: the rotation speed of the feeding counter-roller is 15 - 60 r / min, the rotation speed of the saw-tooth roller is 50 - 500 r / min, the distance between the counter-roller and the saw-tooth roller is 0.5 - 5 mm, the feeding speed is 20 - 150 g / min, the air flow rate of the dust removal and purging system is 20 - 5000 m 3 / h, and the processing speed is 0.4 - 8 kg / h.

[0015] Further, the equipment used for the hybrid modification is one or a combination of a ball mill, a high-speed shearer, a crusher, and a planetary mixer.

[0016] The present invention also discloses a graphene filler prepared by the above preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a preparation method of a graphene filler. The graphene film is surface-modified, and then through primary peeling, a modified graphene pre-filler is obtained. Finally, the final graphene filler is obtained through separation and collection. Compared with the prior art, due to the process of secondary peeling of the thermally reduced graphene oxide film, the method is simple and easy to operate, does not require high-precision equipment, the preparation process is fast, the raw material cost required is low, large-scale production can be achieved, and the technical problem of the complex production process of the existing preparation method is solved.

[0018] Further, the method of the present application utilizes the excellent physical properties and good processing characteristics of the thermally reduced graphene film. Through surface modification, peeling and separation, finally a graphene filler with uniform size specifications and good dispersibility is obtained, ensuring the excellent use performance of the filler, and at the same time improving the yield rate of the subsequent cotton-opener separation process.

[0019] Further, the present application uses a cotton opener for separation and collection. By utilizing the interaction between the hooking and friction of the cotton opener and the holding force received by the modified graphene pre-filler, the product is separated. At the same time, under the action of the air flow, due to the difference in centrifugal force of graphene fillers with different size specifications, the required size fillers are continuously ejected, while other non-compliant pre-fillers are hooked by the saw teeth and separated repeatedly with the rack drum, having the advantages of high production efficiency, simple process flow, and good uniformity of product sheet diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow chart of the preparation of the graphene filler of the present invention; Figure 2 The optical microscopy morphology of the graphene filler prepared by the present invention; Figure 3 The optical microscopy morphology of the graphene filler prepared in Example 1 of the present invention; Figure 4 The optical microscopy morphology of the graphene filler prepared in Example 2 of the present invention; Figure 5 The optical microscopy morphology of the graphene filler prepared in Example 3 of the present invention; Figure 6 The optical microscopy morphology of the graphene filler prepared in Example 4 of the present invention. Detailed implementation manners

[0021] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0022] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0023] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0024] In this article, unless otherwise specified, the terms "comprising", "including", "containing", "having" or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".

[0025] In this article, for the sake of brevity, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0026] The present invention provides a preparation method of a graphene filler, as Figure 1 shown, which includes the following steps: Step 1: Using a graphene oxide slurry, through coating and drying treatment, a graphene oxide film is obtained; Step 2: Subject the graphene oxide film obtained in Step 1 to heat treatment to obtain a graphene film; Step 3: Mix and modify the graphene film obtained in Step 2 with a surface modifier to obtain a modified graphene film premix; Step 4: Subject the modified graphene film premix obtained in Step 3 to refinement and pre-peeling to obtain a modified graphene prefabricated filler; Step 5: Separate and collect the modified graphene prefabricated filler obtained in Step 4 using a carding machine under corresponding process conditions to obtain a graphene filler.

[0027] Preferably, the solid content of the graphene oxide slurry is 0.5% - 10%, and the viscosity is 5000 - 250000 mPas.

[0028] More preferably, the solid content of the graphene oxide slurry is 0.8% - 8%.

[0029] Preferably, the device used for the coating and drying treatment is at least one of a slot die coater, a rotary centrifugal spray coater, and a knife coater; the water content of the graphene oxide film is 10 - 40%; the coating thickness of the coating and drying treatment is 0.5 - 20 mm.

[0030] More preferably, the water content of the graphene oxide film is 20% - 40%; the coating thickness of the coating and drying treatment is 0.5 - 10 mm.

[0031] Preferably, the process parameters of the heat treatment are as follows: when the heat treatment temperature is less than 85°C, the weight loss ratio of the product is 0.4 - 5% / h; when the heat treatment temperature is 85 - 145°C, the weight loss ratio of the product is 0.04 - 2.5% / h; when the heat treatment temperature is 145 - 300°C, the weight loss ratio of the product is 0.005 - 1.5% / h; when the heat treatment temperature is 300 - 1100°C, the heat treatment heating rate is 1 - 15°C / min; when the heat treatment temperature is 1100 - 2400°C, the heat treatment heating rate is 0.5 - 10°C / min; the heat treatment cut-off temperature is 2100 - 2400°C; the heating atmosphere for the heat treatment process at 85 - 500°C and 1100°C - the heat treatment cut-off temperature is at least one or a mixture of air, argon, and nitrogen; the 500 - 1100°C stage of the heat treatment process is vacuum heat treatment, and the vacuum degree is 10 -4 ~10 -6 Torr.

[0032] More preferably, the process parameters of the heat treatment are as follows: for the heat treatment process, when the heat treatment temperature is less than 85°C, the weight loss ratio of the product is 0.4 - 3% / h; when the heat treatment temperature is 85 - 145°C, the weight loss ratio of the product is 0.04 - 1% / h; when the heat treatment temperature is 145 - 300°C, the weight loss ratio of the product is 0.005 - 1.5% / h; when the heat treatment temperature is 300 - 1100°C, the heat treatment heating rate is 3 - 10°C / min; when the heat treatment temperature is 1100 - 2400°C, the heat treatment heating rate is 1.5 - 8°C / min; the heat treatment cut-off temperature is 2250 - 2400°C.

[0033] Preferably, the surface modifier is at least one or a mixture of methyl cellulose, sodium carboxymethyl cellulose, aminopropyltriethoxysilane (KH550), 3-aminopropyltrimethoxysilane (KH540), triaminopropylmethyldiethoxysilane (A2100), N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane (A2120); the modifier mixing equipment is one or a combination of a ball mill, a high-speed shearer, a crusher, and a planetary stirrer; the mass ratio of the surface modifier to the graphene film is 1:(10 - 100); the rotation speed of the mixing equipment is 2000 - 4000 r / min, and the time is 0.5 - 2 h.

[0034] Preferably, the parameters of the cotton opener for the modified graphene prefabricated filler include: the rotation speed of the feeding pair roller is 15 - 60 r / min, the rotation speed of the carding roller is 50 - 500 r / min, the distance between the pair roller and the carding roller is 0.5 - 5 mm, the feeding speed is 20 - 150 g / min, the air flow rate of the dust removal and purging system is 20 - 5000 m 3 / h, the processing speed is 0.4 - 8 kg / h. Preferably, the rotation speed of the feeding pair roller is 15 - 45 r / min, the rotation speed of the carding roller is 80 - 300 r / min, the distance between the pair roller and the carding roller is 0.5 - 3 mm, the feeding speed is 30 - 110 g / min, the air flow rate of the dust removal and purging system is 80 - 2500 m 3 / h, and the processing speed is 1.2 - 5 kg / h.

[0035] The heat treatment process of the graphene oxide film selected in the present invention in combination with the graphene modification scheme can improve the dispersion of the graphene filler in the matrix, ensure the excellent use performance of the filler, and at the same time improve the yield rate of the subsequent cotton opener separation process. By the interaction of the hooking and friction of the cotton opener and the holding force of the modified graphene prefabricated filler, the product is separated. At the same time, under the action of the air flow, using the centrifugal force difference of graphene fillers of different sizes and specifications, the required size fillers are continuously ejected, while other non-compliant prefabricated fillers are hooked by the saw teeth and separated repeatedly with the rack drum.

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0037] In the following embodiments, conventional instrument and equipment in the art are used. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are the conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0038] Example 1 A preparation method of graphene filler, comprising the following steps: The graphene oxide aqueous slurry with a solid content of 3% and a viscosity of 110000 mPas is coated and dried by a slot die coater, the coating thickness is 5 mm, and a graphene oxide film with a water content of 35% is obtained after drying; the graphene oxide film is reduced according to the following heat treatment process: when the temperature is less than 85 °C, the weight loss ratio of the product is 1% / h, heated in an air atmosphere; when the temperature is 85 - 145 °C, the weight loss ratio of the product is 0.4% / h, heated in an argon atmosphere; when the temperature is 145 - 300 °C, the weight loss ratio of the product is 1.3% / h, heated in an air atmosphere; when the temperature is 300 - 1100 °C, the heating rate of the heat treatment is 8 °C / min, and the furnace vacuum degree is 10 - 5 Torr; when the temperature is 1100 - 2300 °C, the heating rate of the heat treatment is 2.5 °C / min, heated in an argon atmosphere; the cut-off temperature of the heat treatment is 2300 °C, and a graphene film is obtained; The obtained graphene film is mixed with 3-aminopropyltriethoxysilane (KH550) and methylcellulose, and the mass ratio of 3-aminopropyltriethoxysilane (KH550): methylcellulose: graphene film is 1:3:100; The graphene film and the modifier are mixed by a ball mill, the rotation speed of the ball mill is 3000 r / min, and the treatment is carried out for 1.5 h to obtain a premixed modified graphene film; Then, the premixed modified graphene film after ball milling treatment is crushed by a crusher, and the rotation speed of the crusher is 3300 r / min to obtain a primary exfoliated modified graphene prefabricated filler; Separate the modified graphene prefabricated filler using a carding machine. The rotational speed of the feeding pair rollers of the carding machine is 25 r / min, the rotational speed of the licker-in is 120 r / min, the distance between the pair rollers and the licker-in is 1 mm, the feeding speed is 90 g / min, the air flow rate of the dust removal and purging system is 1200 m 3 / h, the processing speed is 2.5 kg / h, and graphene filler is obtained. The morphology of the obtained graphene filler is as shown in Figure 3 Figure. It can be seen from the figure that the sheet diameter of the graphene filler is about 10 μm.

[0039] Example 2 A preparation method of graphene filler includes the following steps: Coat and dry the graphene oxide aqueous slurry with a solid content of 3% and a viscosity of 110000 mPas using a slot die coater. The coating thickness is 8 mm, and after drying, a graphene oxide film with a water content of 37% is obtained; Reduce the obtained graphene oxide film according to the following heat treatment process: When the temperature is less than 85 °C, the weight loss ratio of the product is 1% / h, heated in an air atmosphere; When the temperature is 85 - 145 °C, the weight loss ratio of the product is 0.4% / h, heated in an argon atmosphere; When the temperature is 145 - 300 °C, the weight loss ratio of the product is 1.3% / h, heated in an air atmosphere; When the temperature is 300 - 1100 °C, the heating rate of the heat treatment is 8 °C / min, and the furnace vacuum is 10 - 5 Torr; When the temperature is 1100 - 2300 °C, the heating rate of the heat treatment is 2.5 °C / min, heated in an argon atmosphere; The cut-off temperature of the heat treatment is 2300 °C, and a graphene film is obtained; Mix the obtained graphene film with 3-aminopropyltriethoxysilane (KH550) and sodium carboxymethylcellulose. The mass ratio of 3-aminopropyltriethoxysilane (KH550):sodium carboxymethylcellulose:graphene film is 2:4:100; Use a ball mill to mix the graphene film and the modifier. The rotational speed of the ball mill is 2500 r / min, and process for 1 h to obtain the modified graphene prefabricated filler after the first peeling; Separate the modified graphene prefabricated filler using a carding machine. The rotational speed of the feeding pair rollers of the carding machine is 28 r / min, the rotational speed of the licker-in is 120 r / min, the distance between the pair rollers and the licker-in is 1.7 mm, the feeding speed is 40 g / min, the air flow rate of the dust removal and purging system is 2200 m 3 / h, the processing speed is 1.6 kg / h, and graphene filler is obtained. The morphology of the obtained graphene filler is as shown in Figure 4 Figure. It can be seen from the figure that the sheet diameter of the graphene filler is about 20 μm.

[0040] Example 3 A preparation method of graphene filler includes the following steps: The graphene oxide aqueous slurry with a solid content of 5.5% and a viscosity of 170,000 mPas is subjected to coating and drying treatment using a rotary centrifugal spraying coater. The coating thickness is 4 mm, and after drying, a graphene oxide film with a water content of 32% is obtained. The graphene oxide film is reduced according to the following heat treatment process: when the temperature is less than 85°C, the weight loss ratio of the product is 2.5% / h, and it is heated in a nitrogen atmosphere; when the temperature is 85 - 145°C, the weight loss ratio of the product is 0.5% / h, and it is heated in an argon atmosphere; when the temperature is 145 - 300°C, the weight loss ratio of the product is 1.0% / h, and it is heated in an air atmosphere; when the temperature is 300 - 1100°C, the heating rate of the heat treatment is 5°C / min, and the furnace vacuum is 10 -5 Torr; when the temperature is 1100 - 2300°C, the heating rate of the heat treatment is 2°C / min, and it is heated in an argon atmosphere; the cut-off temperature of the heat treatment is 2300°C, and a graphene film is obtained; The obtained graphene film is mixed with 3-aminopropyltrimethoxysilane (KH540) and triaminopropylmethyldiethoxysilane (A2100). The mass ratio of 3-aminopropyltrimethoxysilane (KH540):triaminopropylmethyldiethoxysilane (A2100):graphene film is 0.2:1:100; The graphene film and the modifier are mixed using a ball mill. The rotation speed of the ball mill is 3000 r / min, and it is processed for 1.5 h to obtain a premixed modified graphene film; Then, the premixed modified graphene film after ball milling treatment is crushed using a high-speed shearer. The rotation speed of the high-speed shearer is 3000 r / min to obtain a modified graphene prefabricated filler that is peeled off once; The modified graphene prefabricated filler is separated using a carding machine. The rotation speed of the feed roller of the carding machine is 28 r / min, the rotation speed of the carding roller is 300 r / min, the distance between the feed roller and the carding roller is 0.6 mm, the feeding speed is 70 g / min, the air flow rate of the dust removal and purging system is 2500 m 3 / h, and the processing speed is 1.8 kg / h to obtain a graphene filler. The morphology of the obtained graphene filler is as Figure 5 shown. It can be seen from the figure that the sheet diameter of the graphene filler is about 7 μm.

[0041] Example 4 A preparation method of a graphene filler, comprising the following steps: The graphene oxide aqueous slurry with a solid content of 5.8% and a viscosity of 230,000 mPas was subjected to coating and drying treatment using a rotary centrifugal spraying coater. The coating thickness was 1.5 mm, and a graphene oxide film with a water content of 35% was obtained after drying. The graphene oxide film was reduced according to the following heat treatment process: when the temperature was less than 85 °C, the weight loss ratio of the product was 2.8% / h, and it was heated in an air atmosphere; when the temperature was 85 - 145 °C, the weight loss ratio of the product was 0.7% / h, and it was heated in a 30% argon + 70% nitrogen atmosphere; when the temperature was 145 - 300 °C, the weight loss ratio of the product was 0.04% / h, and it was heated in an air atmosphere; when the temperature was 300 - 1100 °C, the heating rate of the heat treatment was 5 °C / min, and the furnace vacuum was 10 -5 Torr; when the temperature was 1100 - 2300 °C, the heating rate of the heat treatment was 4 °C / min, and it was heated in an argon atmosphere; the heat treatment cut-off temperature was 2280 °C, and a graphene film was obtained; The obtained graphene film was mixed with N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane (A2120). The mass ratio of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane (A2120) to the graphene film was 3.5:100; The graphene film and the modifier were mixed using a planetary mixer. The rotation speed of the planetary mixer was 2500 r / min, and it was processed for 0.5 h to obtain a premix of modified graphene film; Then, the premix of the graphene film after ball milling treatment was crushed using a high-speed shearer. The rotation speed of the high-speed shearer was 3000 r / min to obtain a modified graphene prefabricated filler after the first peeling; The modified graphene prefabricated filler was separated using a carding machine. The rotation speed of the feed roller of the carding machine was 40 r / min, the rotation speed of the licker-in was 250 r / min, the distance between the feed roller and the licker-in was 1 mm, the feeding speed was 100 g / min, the air flow rate of the dust removal and purging system was 2300 m 3 / h, and the processing speed was 4 kg / h to obtain graphene filler. The morphology of the obtained graphene filler is as Figure 6 shown. It can be seen from the figure that the sheet diameter of the graphene filler is about 5 μm.

[0042] Figure 2 This is the optical microscope morphology of the graphene filler prepared by the present invention. It can be seen from the figure that the prepared graphene filler has regular dimensions, few impurities, and good dispersibility.

[0043] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a graphene filler, characterized in that: The following steps are involved: Mixing and modifying the graphene film and the surface modifier to obtain a modified graphene film premix; The modified graphene film premix is ​​subjected to a first exfoliation to obtain a modified graphene preformed filler; The modified graphene preformed filler is separated and collected by using separation equipment to obtain the graphene filler.

2. The method for preparing a graphene filler according to claim 1, characterized in that: The preparation method of the graphene film is as follows: The graphene oxide slurry is coated and dried to obtain a graphene oxide film; then the graphene oxide film is heat-treated to obtain a graphene film.

3. The method for preparing a graphene filler according to claim 2, characterized in that: The graphene oxide slurry has a solid content of 0.5% to 10% and a viscosity of 5000 to 250000 mPas; The water content of the graphene oxide film is 10% to 40%; the coating thickness of the coating and drying process is 0.5 to 20 mm.

4. The method for preparing a graphene filler according to claim 2, characterized in that: The process parameters of the heat treatment are: when the heat treatment temperature is less than 85°C, the product weight loss rate is 0.4-5% / h; when the heat treatment temperature is 85-145°C, the product weight loss rate is 0.04-2.5% / h; when the heat treatment temperature is 145-300°C, the product weight loss rate is 0.005-1.5% / h; when the heat treatment temperature is 300-1100°C, the heat treatment heating rate is 1-15°C / min; when the heat treatment temperature is 1100-2400°C, the heat treatment heating rate is 0.5-10°C / min; Heat treatment cut-off temperature is 2100~2400℃; In the heat treatment, the heating atmosphere at 85-500°C and 1100°C to the heat treatment cut-off temperature is at least one of air, argon, and nitrogen, or a mixture thereof; the 500-1100°C stage is a vacuum heat treatment with a vacuum degree of 10 -4 ~10 -6 Torr.

5. The method for preparing a graphene filler according to claim 1, characterized in that: The mass ratio of the surface modifier to the graphene film is 1:(10-100).

6. The method for preparing a graphene filler according to claim 1, characterized in that: The surface modifier is one or more of methyl cellulose, sodium carboxymethyl cellulose, aminopropyl triethoxy silane, 3-aminopropyl trimethoxy silane, triaminopropyl methyl diethoxy silane and N-(β-aminoethyl-γ-aminopropyl) methyl dimethoxy silane.

7. The method for preparing a graphene filler according to claim 1, characterized in that: The one-time peeling method is thinning pre-peeling; the peeling speed of the thinning pre-peeling is 2000~4000r / min, and the time is 0.5~2h.

8. The method for preparing a graphene filler according to claim 1, characterized in that: The separation equipment is a cotton flossing machine; the process parameters of the separation and collection are: the speed of the feeding roller is 15-60r / min, the speed of the licker-in roller is 50-500r / min, the distance between the roller and the licker-in roller is 0.5-5mm, the feeding speed is 20-150g / min, and the air flow of the dust removal and blowing system is 20-5000m 3 / h, the processing speed is 0.4~8kg / h.

9. The method for preparing a graphene filler according to claim 1, characterized in that: The equipment used for the mixing and modification is one or more combinations of a ball mill, a high-speed shearing machine, a pulverizer, and a planetary mixer.

10. A graphene filler, characterized in that: The method is prepared by any one of claims 1 to 9.

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