Graphene-based heating material and preparation method thereof

Abstract

The invention relates to the technical field of electric heating materials, and discloses a graphene-based heating material and a preparation method thereof.The preparation method comprises the following preparation steps that a binder and a solvent are mixed and stirred evenly, composite graphene heating powder, a stabilizer and a dispersing agent are added, stirring is conducted for 2-3 h at the speed of 500-800 r / min, and heating slurry is obtained; spraying a conductive adhesive on a mica plate, and attaching an electrode material to obtain a mica plate base material; and spraying the heating slurry onto a mica plate base material, and carrying out hot-pressing curing to obtain the heating material. The mica plate is used as a substrate of the heating material, has high hardness and strong impact resistance, is not easy to deform, and provides stable support for the heating coating, and the graphene-based heating material formed by matching the mica plate with the graphene heating slurry has the effects of rapid temperature rise and uniform heat distribution.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electric heating materials, in particular to a graphene-based heating material and a preparation method thereof. BACKGROUND

[0002] The heating material utilizes the principle of converting electric energy into heat energy, has advantages of environmental protection and convenient installation, and the like, the heating material is formed by coating a heating slurry on the surface of a base material and curing at high temperature, wherein the heating material prepared by adopting a mica heating plate matched with a graphene heating slurry has the characteristics of insulation, high-temperature resistance and rapid heat conduction, greatly improves the temperature rising speed and temperature, realizes uniform heat distribution, and guarantees stable and efficient heating in a low-temperature environment.

[0003] The currently commonly used heating material has unstable performance, the temperature rising speed is difficult to meet the requirement of rapid heating, the power is low, the heating effect is poor, the working temperature is insufficient, and the heating efficiency is low, and therefore it is necessary to develop the graphene-based heating material prepared by adopting the mica heating plate matched with the graphene heating slurry, but it is necessary to pay attention to the fact that the graphene in the graphene heating slurry is easy to agglomerate, which leads to poor heating effect and uneven heat distribution, and the heat conduction path of the graphene sheet layer is discontinuous, which affects the heating effect. SUMMARY

[0004] The application provides a graphene-based heating material and a preparation method thereof, and solves the problems that the graphene in a graphene heating slurry is easy to agglomerate, which leads to poor heating effect and uneven heat distribution, and the heat conduction path of the graphene sheet layer is discontinuous, which affects the heating effect.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0007] S1. mixing a binder and a solvent, stirring uniformly, adding composite graphene heating powder, a stabilizer and a dispersant, stirring at 500-800 r / min for 2-3 h to obtain a heating slurry;

[0008] S2. spraying conductive glue on a mica plate, and then bonding an electrode material to obtain a mica plate base material;

[0009] S3. spraying the heating slurry on the mica plate base material, and curing by hot pressing to obtain a heating material;

[0010] The composite graphene heating powder is obtained by adhering a composite layered material to the surface of carbon fibers through polydopamine, and then mixing and reacting with tannic acid and carbon nanotubes;

[0011] The composite layered material is obtained by synthesizing nanocarbon dots on the surface of silver nanosheets, and then intercalating graphene oxide.

[0012] Further, in step S1, the mass ratio of the binder, the solvent, the composite graphene heating powder, the stabilizer, and the dispersant is (25-35):(35-40):(30-40):(1-2):(2-3).

[0013] Further, in step S2, the spraying amount of the conductive adhesive on the mica plate is 0.8-1.2 mg / cm 2 , and the spraying pressure is 0.25-0.35 MPa.

[0014] Further, in step S3, the spraying amount of the heating slurry on the mica plate substrate is 2.8-3.5 mg / cm 2 , and the spraying pressure is 0.3-0.4 MPa.

[0015] Further, the viscosity of the conductive adhesive is 8000-10000 Pa·s.

[0016] Further, the electrode material is a copper foil with a thickness of 2-3 mm.

[0017] Further, the thickness of the mica plate is 5-10 mm.

[0018] Further, the thickness of the heating material is 7.5-13.5 mm.

[0019] Further, the binder is selected from water-based acrylic resin with a solid content of 60-65%.

[0020] Further, the solvent is selected from ethanol or methanol.

[0021] Further, the stabilizer is silicon dioxide particles with a particle size of 10-30 μm.

[0022] Further, the dispersant is selected from dispersant BYK-190 or polyvinylpyrrolidone.

[0023] Further, the composite graphene heating powder is prepared by the following steps:

[0024] A1. Citric acid monohydrate is added to deionized water and stirred until completely dissolved. After adjusting the pH to neutral, silver nanosheets are added, and after uniform stirring, the mixture is placed in a reaction kettle and reacted at 170-190℃ for 5-6 h. After cooling to room temperature, the mixture is filtered, washed, and dried to obtain carbon dot-loaded silver nanosheets;

[0025] A2. Graphene oxide and carbon dot-loaded silver nanosheets are added to deionized water, and after ultrasonic treatment, the mixture is filtered, washed, and dried to obtain a composite layered material.

[0026] A3. Carbon fibers were added to Tris-HCl buffer solution, stirred uniformly, dopamine was added, after stirring reaction, filtration, washing, drying, to obtain polydopamine modified carbon fiber;

[0027] A4. Polydopamine modified carbon fiber and composite layered material were added to deionized water, stirred, after standing, filtration, washing, drying, to obtain modified carbon fiber;

[0028] A5. Tannic acid was added to ethanol, stirred until completely dissolved, carbon nanotubes were added, after stirring reaction, modified carbon fiber was added, continue to stir reaction, filtration, washing, drying, to obtain composite graphene heating powder.

[0029] Further, in the above A1 reaction process, a large number of oxygen-containing functional groups, hydroxyl groups, on the surface of silver nanosheets can be chemically combined with citric acid monohydrate, so that citric acid monohydrate is adsorbed on the surface of silver nanosheets, and high-temperature treatment is carried out at 170-190℃, so that citric acid monohydrate is decomposed by heat, and the formed carbon atoms are aggregated to form a core, so that nanocarbon dots are formed on the surface of silver nanosheets, and silver nanosheets loaded with nanocarbon dots are obtained.

[0030] Further, in the above A2 reaction process, graphene oxide has a multi-layer structure, and after ultrasonic treatment, silver nanosheets loaded with carbon dots are intercalated between the layers of graphene oxide, which can effectively increase the spacing between the layers of graphene oxide and retain the layered structure of graphene oxide, forming a composite layered material.

[0031] Further, in the above A3 reaction process, in the Tris-HCl buffer solution, dopamine can self-polymerize on the surface of carbon fibers to form polydopamine, so that the carbon fibers carry a large number of phenolic hydroxyl groups, and polydopamine modified carbon fibers are obtained, which improve the surface activity of carbon fibers and facilitate the deposition of composite layered materials on the surface of carbon fibers.

[0032] Further, in the above A4 reaction process, polydopamine modified carbon fiber has excellent adhesion and contains a large number of phenolic hydroxyl groups, so that the composite layered material adheres to the surface of the polydopamine modified carbon fiber, and a modified carbon fiber is obtained.

[0033] Further, in the above A5 reaction process, tannic acid contains a large number of phenolic hydroxyl structures and has excellent adhesion, which can adhere to the surface of carbon nanotubes, and the tannic acid modified carbon nanotubes contain hydroxyl groups that can be chemically combined with the oxygen-containing functional groups of the composite layered material on the surface of the modified carbon fiber, so that the modified carbon fiber forms a crosslinked network structure, and a composite graphene heating powder is obtained.

[0034] Further, in step A1, the amount ratio of citric acid monohydrate, deionized water and silver nanosheets is (2-3)g:(45-55)mL:(3.2-3.4)g.

[0035] Further, in step A2, the dosage ratio of graphene oxide, silver nanosheet loaded carbon dots and deionized water is (1.1-1.5) g:(0.8-1.2) g:(75-85) mL.

[0036] Further, in step A3, the dosage ratio of carbon fiber, Tris-HCl buffer and dopamine is (2.1-2.5) g:(45-55) mL:(0.1-0.3) g.

[0037] Further, in step A4, the dosage ratio of polydopamine modified carbon fiber, composite layered material and deionized water is (2.5-2.7) g:(1.4-1.6) g:(85-95) mL.

[0038] Further, in step A5, the dosage ratio of tannic acid, ethanol, carbon nanotubes and modified carbon fiber is (0.6-1) g:(45-55) mL:(0.8-1.2) g:(2.5-2.7) g.

[0039] Further, the silver nanosheet has a size of 2-5 μm.

[0040] Further, the carbon fiber has a diameter of 5-10 μm and a length of 0.1-1 mm.

[0041] Further, the graphene oxide has a size of 2-5 μm and a thickness of 50-100 nm.

[0042] Further, the carbon nanotube has an aspect ratio of 20:1 and a diameter of 5-10 nm.

[0043] The present application has the following beneficial effects:

[0044] (1) In the technical scheme of the present application, nano carbon dots are formed on the surface of silver nanosheets, and the nano carbon dots and silver nanosheets have a low resistivity. After the heating material is electrified, the electric energy can be converted into heat energy, thereby improving the heating effect. The silver nanosheet loaded with nano carbon dots is intercalated with graphene oxide. On the one hand, a composite layered material is formed, which forms a heat conduction path in the heating slurry, realizes uniform distribution of heat, and the composite layered material is beneficial to the passage of electric current through the graphene oxide, thereby converting electric energy into heat energy and improving the heating effect. On the other hand, the composite layered material can absorb external stress, thereby improving the softness of the heating material and avoiding the graphene oxide from falling off under external force, thereby affecting the heating effect. In addition, the nano carbon dots between the layers of the composite layered material act as a lubricating component, so that the composite layered material can move back and forth under external force, has excellent compression resilience, has high flexibility, and makes the heating material adapt to different shapes and surfaces of the base material, thereby improving the application range of the heating material.

[0045] (2) In the technical scheme of the present application, the composite layered material is loaded on the surface of the carbon fiber through polydopamine. On the one hand, the carbon fiber serves as a carrier of the composite layered material, can load more composite layered material, improve the heating efficiency, and improve the dispersity of the composite layered material in the heating slurry, so that the composite layered material can be uniformly dispersed on the surface of the mica plate, realize uniform heat distribution, avoid the easy agglomeration of the graphene-based composite layered material, leading to heat concentration and uneven distribution, and affect the heating effect. On the other hand, the carbon fiber is randomly distributed in the heating slurry, improves the contact area of the heating slurry and the mica plate, enhances the bonding force of the heating slurry and the mica plate, and the randomly distributed carbon fiber can absorb and weaken external force, avoiding the falling of the heating material in the process of long-term cold and hot cycle or mechanical vibration. In addition, the carbon fiber is compounded with the composite layered material, which can form a continuous conductive network in the slurry. When the current passes through, it can convert electrical energy into heat energy, reduce resistance loss, has excellent electrical conductivity and electrical heating conversion efficiency, and significantly improves the heating effect.

[0046] (3) In the technical scheme of the present application, tannic acid contains a large number of phenolic hydroxyl structures, has excellent adhesion, can adhere to the surface of carbon nanotubes, is conducive to the carbon nanotubes as the crosslinking site of modified carbon fiber, forms a crosslinked network structure, so that the composite graphene heating powder forms a heat conduction path, and improves the heating effect. Mixing and reacting the modified carbon fiber and the tannic acid modified carbon nanotube, on the one hand, the tannic acid modified carbon nanotube as a nano crosslinking agent, makes the modified carbon fiber form a crosslinked network structure, so that the composite heating powder forms a heat conduction path, and can convert electrical energy into heat energy, reduce resistance loss, and then realize rapid heating of the heating material, uniform heat distribution, on the other hand, the tannic acid modified carbon nanotube can be chemically bonded with the mica plate, enhances the adhesion of the composite graphene heating powder on the mica plate, avoids the falling of the heating material coating in the long-term cold and hot cycle or mechanical vibration, and prolongs the service life of the heating material. In addition, the carbon nanotube has high electrical conductivity, can reduce the overall resistance of the heating slurry, so that the energy loss is smaller when the current passes through, and the heating rate of the heating material is improved.

[0047] (4) In the technical scheme of the present application, the mica plate serves as the substrate of the heating material, has high hardness, strong impact resistance, and is not easy to deform, provides stable support for the heating coating, avoids the damage of the heating material caused by the deformation of the substrate, therefore, the heating material prepared by the present application has the effects of high temperature resistance, rapid heating and uniform heat distribution. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0049] The raw materials used in the embodiments of the present application are shown below, and all the reagents used are analytical grade.

[0050] The mica plate model is hp-5, with a thickness of 8 mm, purchased from Baoying County Zhongjing Electrical Material Factory.

[0051] The electrode material is copper foil, with a thickness of 2.5 mm.

[0052] The conductive adhesive model is 80P, with a viscosity of 9000 Pa·s, purchased from Huizhou Tenghui Technology Co., Ltd.

[0053] The binder is water-based acrylic resin with a solid content of 63%, the solvent is ethanol, the stabilizer is silica particles with a particle size of 20 μm, and the dispersant is dispersant BYK-190.

[0054] The silver nanosheet has a size of 3 μm.

[0055] The carbon fiber has a diameter of 7 μm and a length of 0.5 mm.

[0056] The graphene oxide has a size of 3 μm and a thickness of 80 nm.

[0057] The carbon nanotube has an aspect ratio of 20:1 and a diameter of 6 nm.

[0058] Embodiment 1

[0059] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0060] S1. Mix the water-based acrylic resin and ethanol, stir uniformly, add the composite graphene heating powder, silica particles and dispersant BYK-190, stir at 500 r / min for 2 h to obtain a heating slurry; the mass ratio of the water-based acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 is 25:35:30:1:2;

[0061] S2. Spray the conductive adhesive on the mica plate, the spraying amount of the conductive adhesive on the mica plate is 0.8 mg / cm 2 , the spraying pressure is 0.25 MPa, and then the copper foil with a thickness of 2.5 mm is attached to obtain a mica plate base material;

[0062] S3. The heat-generating slurry is sprayed onto the mica plate substrate, and the spraying amount of the heat-generating slurry on the mica plate substrate is 2.8 mg / cm 2 , the spraying pressure is 0.3 MPa, and the heat-pressing curing temperature is 250 DEG C, and the pressure is 4 MPa, to obtain the heat-generating material.

[0063] The composite graphene heat-generating powder is prepared by the following steps:

[0064] A1. 2 g of citric acid monohydrate is added to 45 mL of deionized water, stirred until completely dissolved, and a 1 mol / L sodium hydroxide solution is added to adjust the pH to 7. 3.2 g of silver nanosheets is added, stirred at 70 DEG C for 10 min, placed in a reaction kettle, reacted at 170 DEG C for 5 h, cooled to room temperature, filtered, deionized water washed 3 times, and dried in an 80 DEG C oven for 10 min to obtain silver nanosheets loaded with carbon dots;

[0065] A2. 1.1 g of graphene oxide and 0.8 g of silver nanosheets loaded with carbon dots are added to 75 mL of deionized water, ultrasonically treated at 40 KHz for 10 min, filtered, deionized water washed 3 times, and dried in an 80 DEG C oven for 10 min to obtain a composite layered material;

[0066] A3. 2.1 g of carbon fibers is added to 45 mL of Tris-HCl buffer with a pH of 8.5, stirred uniformly, 0.1 g of dopamine is added, and stirred at 25 DEG C and 800 r / min for 4 h. After filtration, deionized water is washed 3 times, and dried in a 70 DEG C oven for 10 min to obtain polydopamine modified carbon fibers;

[0067] A4. 2.5 g of polydopamine modified carbon fibers and 1.4 g of composite layered material are added to 85 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, deionized water washed 3 times, and dried in a 70 DEG C oven for 10 min to obtain modified carbon fibers;

[0068] A5. 0.6 g of tannic acid is added to 45 mL of ethanol, stirred until completely dissolved, 0.8 g of carbon nanotubes is added, and stirred at 60 DEG C for 30 min. 2.6 g of modified carbon fibers is added, and the stirring is continued for 30 min. After filtration, deionized water is washed 3 times, and dried in a 70 DEG C oven for 10 min to obtain composite graphene heat-generating powder.

[0069] Example 2

[0070] A method for preparing a graphene-based heat-generating material, comprising the following preparation steps:

[0071] S1. Mix the aqueous acrylic resin and ethanol, stir until uniform, add the composite graphene heating powder, silica particles and dispersant BYK-190, stir at 700 r / min for 2.5 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 is 30:38:35:1.5:2.5;

[0072] S2. Spray the conductive glue on the mica plate, the spraying amount of the conductive glue on the mica plate is 1 mg / cm 2 , the spraying pressure is 0.3 MPa, and then a copper foil with a thickness of 2.5 mm is attached to obtain a mica plate substrate;

[0073] S3. Spray the heating slurry on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate is 3.1 mg / cm 2 , the spraying pressure is 0.35 MPa, and then heat pressing and curing are performed, the heat pressing and curing temperature is 255℃, the pressure is 4.5 MPa, to obtain a heating material.

[0074] The composite graphene heating powder is prepared by the following steps:

[0075] A1. Add 2.5 g of citric acid monohydrate to 50 mL of deionized water, stir until completely dissolved, add a 1 mol / L sodium hydroxide solution to adjust the pH to 7, add 3.3 g of silver nanosheets, stir at 70℃ for 10 min, place in a reaction kettle, react at 180℃ for 5.5 h, cool to room temperature, filter, deionized water wash 3 times, dry in an 80℃ oven for 10 min to obtain silver nanosheets loaded with carbon dots;

[0076] A2. Add 1.3 g of graphene oxide and 1 g of silver nanosheets loaded with carbon dots to 80 mL of deionized water, ultrasonic treat at 40 KHz for 10 min, filter, deionized water wash 3 times, dry in an 80℃ oven for 10 min to obtain a composite layered material;

[0077] A3. Add 2.3 g of carbon fibers to 50 mL of Tris-HCl buffer with a pH of 8.5, stir until uniform, add 0.2 g of dopamine, stir at 25℃, 800 r / min for 4 h, filter, deionized water wash 3 times, dry in a 70℃ oven for 10 min to obtain polydopamine modified carbon fibers;

[0078] A4. Add 2.6 g of polydopamine modified carbon fibers and 1.5 g of composite layered material to 90 mL of deionized water, stir at 900 r / min for 25 min, stand for 1 h, filter, deionized water wash 3 times, dry in a 70℃ oven for 10 min to obtain modified carbon fibers;

[0079] A5. 0.8 g of tannic acid was added to 50 mL of ethanol, stirred until completely dissolved, 1 g of carbon nanotubes was added, stirred at 60°C for 30 min, 2.6 g of modified carbon fiber was added, and the stirring reaction was continued for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain composite graphene heating powder.

[0080] Example 3

[0081] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0082] S1. The aqueous acrylic resin and ethanol were mixed and stirred uniformly, and the composite graphene heating powder, silica particles and dispersant BYK-190 were added, stirred at 800 r / min for 3 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 was 35:40:40:2:3;

[0083] S2. The conductive adhesive was sprayed on the mica plate, the spraying amount of the conductive adhesive on the mica plate was 1.2 mg / cm 2 , the spraying pressure was 0.35 MPa, and a copper foil with a thickness of 2.5 mm was attached to obtain a mica plate substrate;

[0084] S3. The heating slurry was sprayed on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate was 3.5 mg / cm 2 , the spraying pressure was 0.4 MPa, and the heating material was obtained by heat pressing and curing at a temperature of 260°C and a pressure of 5 MPa.

[0085] The composite graphene heating powder was prepared by the following steps:

[0086] A1. 3 g of citric acid monohydrate was added to 55 mL of deionized water, stirred until completely dissolved, a 1 mol / L sodium hydroxide solution was added to adjust the pH to 7, 3.4 g of silver nanosheets was added, stirred at 70°C for 10 min, placed in a reaction kettle, reacted at 190°C for 6 h, cooled to room temperature, filtered, washed with deionized water for 3 times, and dried in an oven at 80°C for 10 min to obtain silver nanosheets loaded with carbon dots;

[0087] A2. 1.5 g of graphene oxide and 1.2 g of silver nanosheets loaded with carbon dots were added to 85 mL of deionized water, ultrasonically treated at 40 KHz for 10 min, filtered, washed with deionized water for 3 times, and dried in an oven at 80°C for 10 min to obtain a composite layered material;

[0088] A3. 2.5 g of carbon fiber was added to 55 mL of Tris-HCl buffer with pH 8.5, stirred uniformly, 0.3 g of dopamine was added, stirred at 25℃, 800 r / min for 4 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain polydopamine modified carbon fiber;

[0089] A4. 2.7 g of polydopamine modified carbon fiber and 1.6 g of composite layered material were added to 95 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain modified carbon fiber;

[0090] A5. 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 1.2 g of carbon nanotube was added, stirred at 60℃ for 30 min, 2.7 g of modified carbon fiber was added, and the stirring was continued for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain composite graphene heating powder.

[0091] Comparative Example 1

[0092] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0093] S1. Water-based acrylic resin and ethanol were mixed and stirred uniformly, composite graphene heating powder, silica particles and dispersant BYK-190 were added, stirred at 800 r / min for 3 h, to obtain heating slurry; the mass ratio of water-based acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 was 35:40:40:2:3;

[0094] S2. The conductive adhesive was sprayed on the mica plate, the spraying amount of the conductive adhesive on the mica plate was 1.2 mg / cm 2 , the spraying pressure was 0.35 MPa, and then a copper foil with a thickness of 2.5 mm was attached, to obtain a mica plate substrate;

[0095] S3. The heating slurry was sprayed on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate was 3.5 mg / cm 2 , the spraying pressure was 0.4 MPa, and then hot-pressing curing was performed, the hot-pressing curing temperature was 260℃, and the pressure was 5 MPa, to obtain a heating material.

[0096] The composite graphene heating powder was prepared by the following steps:

[0097] A1. 1.5 g of graphene oxide and 1.2 g of silver nanosheet were added to 85 mL of deionized water, ultrasonically treated at 40 KHz for 10 min, filtered, washed with deionized water for 3 times, dried in an oven at 80℃ for 10 min, to obtain a composite layered material;

[0098] A2. 2.5 g of carbon fiber was added to 55 mL of Tris-HCl buffer with pH of 8.5, stirred uniformly, 0.3 g of dopamine was added, stirred at 800 r / min at 25℃ for 4 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain polydopamine modified carbon fiber;

[0099] A3. 2.7 g of polydopamine modified carbon fiber and 1.6 g of composite layered material were added to 95 mL of deionized water, stirred at 900 r / min for 25 min, after standing for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain modified carbon fiber;

[0100] A4. 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 1.2 g of carbon nanotube was added, stirred at 60℃ for 30 min, 2.7 g of modified carbon fiber was added, continued to stir for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain composite graphene heating powder.

[0101] Comparative Example 2

[0102] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0103] S1. The aqueous acrylic resin and ethanol were mixed and stirred uniformly, and the composite graphene heating powder, silica particles and dispersant BYK-190 were added, stirred at 800 r / min for 3 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 was 35:40:40:2:3;

[0104] S2. The conductive adhesive was sprayed on the mica plate, the spraying amount of the conductive adhesive on the mica plate was 1.2 mg / cm 2 , the spraying pressure was 0.35 MPa, and a copper foil with a thickness of 2.5 mm was attached to obtain a mica plate substrate;

[0105] S3. The heating slurry was sprayed on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate was 3.5 mg / cm 2 , the spraying pressure was 0.4 MPa, and the heating material was obtained by heat pressing and curing at a temperature of 260℃ and a pressure of 5 MPa.

[0106] The composite graphene heating powder is prepared by the following steps:

[0107] A1. 3 g of citric acid monohydrate was added to 55 mL of deionized water, stirred until completely dissolved, and a 1 mol / L sodium hydroxide solution was added to adjust the pH to 7. 3.4 g of silver nanosheets was added, stirred at 70°C for 10 min, placed in a reaction kettle, reacted at 190°C for 6 h, cooled to room temperature, filtered, deionized water washed 3 times, and dried in an 80°C oven for 10 min to obtain carbon dot loaded silver nanosheets;

[0108] A2. 1.5 g of graphene oxide and 1.2 g of carbon dot loaded silver nanosheets were added to 85 mL of deionized water, stirred until uniform, filtered, deionized water washed 3 times, and dried in an 80°C oven for 10 min to obtain a composite material;

[0109] A3. 2.5 g of carbon fiber was added to 55 mL of Tris-HCl buffer with a pH of 8.5, stirred until uniform, 0.3 g of dopamine was added, and stirred at 25°C, 800 r / min for 4 h. After filtration, deionized water was washed 3 times, and dried in a 70°C oven for 10 min to obtain polydopamine modified carbon fiber;

[0110] A4. 2.7 g of polydopamine modified carbon fiber and 1.6 g of composite material were added to 95 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, deionized water washed 3 times, and dried in a 70°C oven for 10 min to obtain modified carbon fiber;

[0111] A5. 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 1.2 g of carbon nanotubes was added, and stirred at 60°C for 30 min. 2.7 g of modified carbon fiber was added and continued to stir for 30 min. After filtration, deionized water was washed 3 times, and dried in a 70°C oven for 10 min to obtain composite graphene heating powder.

[0112] Comparative Example 3

[0113] A method for preparing a graphene-based heating material, comprising the following preparation steps:

[0114] S1. The aqueous acrylic resin and ethanol were mixed and stirred until uniform, and the composite graphene heating powder, silica particles, and dispersant BYK-190 were added and stirred at 800 r / min for 3 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles, and dispersant BYK-190 was 35:40:40:2:3;

[0115] S2. The conductive adhesive was sprayed on the mica plate, and the spraying amount of the conductive adhesive on the mica plate was 1.2 mg / cm2 The mica plate substrate is obtained by spraying the heat-generating slurry on the mica plate substrate at a spraying pressure of 0.35 MPa, and then bonding a copper foil with a thickness of 2.5 mm.

[0116] S3. The heat-generating slurry is sprayed onto the mica plate substrate, and the spraying amount of the heat-generating slurry on the mica plate substrate is 3.5 mg / cm 2 The heat-generating material is obtained by heat pressing and curing the heat-generating slurry at a heat pressing and curing temperature of 260 DEG C and a pressure of 5 MPa.

[0117] The composite graphene heat-generating powder is prepared by the following steps:

[0118] A1. 3 g of citric acid monohydrate is added to 55 mL of deionized water, stirred until completely dissolved, and a 1 mol / L sodium hydroxide solution is added to adjust the pH to 7. 3.4 g of silver nanosheets is added, stirred at 70 DEG C for 10 min, placed in a reaction kettle, reacted at 190 DEG C for 6 h, cooled to room temperature, filtered, deionized water washed 3 times, and dried in an 80 DEG C oven for 10 min to obtain silver nanosheets loaded with carbon dots;

[0119] A2. 1.5 g of graphene oxide and 1.2 g of silver nanosheets loaded with carbon dots are added to 85 mL of deionized water, ultrasonically treated at 40 KHz for 10 min, filtered, deionized water washed 3 times, and dried in an 80 DEG C oven for 10 min to obtain a composite layered material;

[0120] A3. 2.7 g of carbon fibers and 1.6 g of the composite layered material are added to 95 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, deionized water washed 3 times, and dried in a 70 DEG C oven for 10 min to obtain modified carbon fibers;

[0121] A4. 1 g of tannic acid is added to 55 mL of ethanol, stirred until completely dissolved, 1.2 g of carbon nanotubes is added, and stirred at 60 DEG C for 30 min. 2.7 g of modified carbon fibers is added, and the stirring is continued for 30 min. The mixture is filtered, deionized water washed 3 times, and dried in a 70 DEG C oven for 10 min to obtain a composite graphene heat-generating powder.

[0122] Comparative Example 4

[0123] A method for preparing a graphene-based heat-generating material, comprising the following preparation steps:

[0124] S1. Mix the aqueous acrylic resin and ethanol, stir until uniform, add the composite graphene heating powder, silica particles and dispersant BYK-190, stir at 800 r / min for 3 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 is 35:40:40:2:3;

[0125] S2. Spray the conductive glue on the mica plate, the spraying amount of the conductive glue on the mica plate is 1.2 mg / cm 2 , the spraying pressure is 0.35 MPa, and then a copper foil with a thickness of 2.5 mm is attached to obtain a mica plate substrate;

[0126] S3. Spray the heating slurry on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate is 3.5 mg / cm 2 , the spraying pressure is 0.4 MPa, and then heat pressing and curing are performed, the heat pressing and curing temperature is 260℃, and the pressure is 5 MPa to obtain a heating material.

[0127] The composite graphene heating powder is prepared by the following steps:

[0128] A1. Add 3 g of citric acid monohydrate to 55 mL of deionized water, stir until completely dissolved, add a 1 mol / L sodium hydroxide solution to adjust the pH to 7, add 3.4 g of silver nanosheets, stir at 70℃ for 10 min, place in a reaction kettle, react at 190℃ for 6 h, cool to room temperature, filter, deionized water wash 3 times, and dry in an 80℃ oven for 10 min to obtain silver nanosheets loaded with carbon dots;

[0129] A2. Add 1.5 g of graphene oxide and 1.2 g of silver nanosheets loaded with carbon dots to 85 mL of deionized water, ultrasonic treat at 40 KHz for 10 min, filter, deionized water wash 3 times, and dry in an 80℃ oven for 10 min to obtain a composite layered material;

[0130] A3. Add 2.5 g of carbon fibers to 55 mL of Tris-HCl buffer with a pH of 8.5, stir until uniform, add 0.3 g of dopamine, stir at 25℃ and 800 r / min for 4 h, filter, deionized water wash 3 times, and dry in a 70℃ oven for 10 min to obtain polydopamine modified carbon fibers;

[0131] A4. Add 2.7 g of polydopamine modified carbon fibers and 1.6 g of composite layered material to 95 mL of deionized water, stir at 900 r / min for 25 min, stand for 1 h, filter, deionized water wash 3 times, and dry in a 70℃ oven for 10 min to obtain modified carbon fibers;

[0132] A5. 2.2 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 2.7 g of modified carbon fiber was added, stirred at 60°C for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain composite graphene heating powder.

[0133] Comparative Example 5

[0134] A preparation method of a graphene-based heating material, comprising the following preparation steps:

[0135] S1. The aqueous acrylic resin and ethanol were mixed and stirred uniformly, and the composite graphene heating powder, silica particles and dispersant BYK-190 were added, stirred at 800 r / min for 3 h to obtain a heating slurry; the mass ratio of the aqueous acrylic resin, ethanol, composite graphene heating powder, silica particles and dispersant BYK-190 was 35:40:40:2:3;

[0136] S2. The conductive adhesive was sprayed on the mica plate, the spraying amount of the conductive adhesive on the mica plate was 1.2 mg / cm 2 , the spraying pressure was 0.35 MPa, and then a copper foil with a thickness of 2.5 mm was attached to obtain a mica plate substrate;

[0137] S3. The heating slurry was sprayed on the mica plate substrate, the spraying amount of the heating slurry on the mica plate substrate was 3.5 mg / cm 2 , the spraying pressure was 0.4 MPa, and then heat pressing and curing were performed, the heat pressing and curing temperature was 260°C, and the pressure was 5 MPa to obtain a heating material.

[0138] The composite graphene heating powder was prepared by the following steps:

[0139] A1. 3 g of citric acid monohydrate was added to 55 mL of deionized water, stirred until completely dissolved, a 1 mol / L sodium hydroxide solution was added to adjust the pH to 7, 3.4 g of silver nanosheets was added, stirred at 70°C for 10 min, placed in a reaction kettle, reacted at 190°C for 6 h, cooled to room temperature, filtered, washed with deionized water for 3 times, dried in an oven at 80°C for 10 min to obtain carbon dot-loaded silver nanosheets;

[0140] A2. 1.5 g of graphene oxide and 1.2 g of carbon dot-loaded silver nanosheets were added to 85 mL of deionized water, ultrasonically treated at 40 KHz for 10 min, filtered, washed with deionized water for 3 times, dried in an oven at 80°C for 10 min to obtain a composite layered material;

[0141] A3. 2.5 g of carbon fiber was added to 55 mL of Tris-HCl buffer with pH 8.5, stirred uniformly, 0.3 g of dopamine was added, stirred at 25°C, 800 r / min for 4 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain polydopamine modified carbon fiber;

[0142] A4. 2.7 g of polydopamine modified carbon fiber and 1.6 g of composite layered material were added to 95 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain modified carbon fiber;

[0143] A5. 1 g of polydopamine was added to 55 mL of ethanol, stirred until completely dissolved, 1.2 g of carbon nanotube was added, stirred at 60°C for 30 min, 2.7 g of modified carbon fiber was added, and the stirring was continued for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain composite graphene heating powder.

[0144] The heating materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance detection.

[0145] The thickness of the heating material used for testing was 10 mm, and the size was 100x100 mm. The heating material was subjected to power-on test at a voltage of 6V and a current of 2 mA, and the temperature rise rate and the electric-thermal conversion rate of the heating material were tested by using an infrared thermal imager;

[0146] Temperature uniformity test: nine-grid dotting method was used, and the temperature at different positions of the heating material was measured by using a thermocouple. The average value of the maximum temperature difference was calculated to represent the temperature uniformity of the heating material.

[0147] Flexibility test: the above-prepared heating material was rubbed for 50 times, and whether the heating layer fell off was observed.

[0148] The test results are shown in Table 1 below.

[0149] Table 1 Performance detection of the heating materials prepared in Examples 1-3 and Comparative Examples 1-5

[0150]

[0151] As can be seen from the data in Table 1, the heating material prepared in Example 1-3 has a high temperature rise rate, and the heat is uniformly distributed.

[0152] The comparative example 1 replaces the carbon dot loaded silver nanosheet with the silver nanosheet to prepare the composite graphene heating powder coated on the heating material, and the heating rate and temperature uniformity decrease, which proves that the nanocarbon dots are formed on the surface of the silver nanosheet, the nanocarbon dots and the silver nanosheet have a lower resistivity, and after the heating material is electrified, the electric energy can be converted into heat energy to improve the heating effect, and the nanocarbon dots as the lubricating component enable the composite layered material to move back and forth under the action of external force, have excellent compression resilience, and have high flexibility.

[0153] The comparative example 2 replaces the composite layered material with the composite material to prepare the composite graphene heating powder coated on the heating material, and the heating rate and temperature uniformity decrease, which proves that the silver nanosheet loaded with nanocarbon dots intercalates the graphene oxide to form the composite layered material, forms a heat conduction path in the heating slurry, realizes uniform heat distribution, and is conducive to the current passing through the graphene oxide to convert the electric energy into heat energy to improve the heating effect, in addition, the composite layered material can absorb external stress to improve the softness of the heating material, avoid the graphene oxide from falling off under the action of external force, and affect the heating effect.

[0154] The comparative example 3 replaces the polydopamine modified carbon fiber with the carbon fiber to prepare the composite graphene heating powder coated on the heating material, and the heating rate and temperature uniformity decrease, which proves that the composite layered material is loaded on the surface of the carbon fiber through the polydopamine to realize uniform heat distribution, avoid the graphene-based composite layered material from easily agglomerating to cause heat concentration and uneven distribution, affect the heating effect, and the carbon fiber is compounded with the composite layered material to easily form a continuous conductive network in the slurry, and when the current passes through, the electric energy can be converted into heat energy to reduce the resistance loss, have excellent electrical conductivity and electric heating conversion efficiency, and significantly improve the heating effect.

[0155] The comparative example 4 replaces the carbon nanotube with the tannic acid to prepare the composite graphene heating powder coated on the heating material, and the heating rate and temperature uniformity decrease, which proves that the carbon nanotube has high electrical conductivity, can reduce the overall resistance of the heating slurry, makes the energy loss smaller when the current passes through, improves the heating rate of the heating material, and the carbon nanotube mixed with the tannic acid is conducive to the carbon nanotube as a crosslinking site of the modified carbon fiber to form a crosslinked network structure, so that the composite graphene heating powder forms a heat conduction path to improve the heating effect.

[0156] The comparative example 5 replaces the tannic acid with the composite graphene heating powder prepared by polydopamine to coat on the heating material, and the heating rate and temperature uniformity decrease, which proves that the tannic acid modified carbon nanotube can be bonded with the mica plate by chemical bond, enhances the adhesion of the composite graphene heating powder on the mica plate, prolongs the service life of the heating material, and the tannic acid modified carbon nanotube as a nano crosslinking agent makes the modified carbon fiber form a crosslinked network structure, makes the composite heating powder form a heat conduction path, realizes the rapid heating of the heating material, and the heat is uniformly distributed.

[0157] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0158] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as it does not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method for producing a graphene-based heat generating material, characterized by, The preparation steps include: S1. Mix the binder and solvent, stir until uniform, add the composite graphene heating powder, stabilizer and dispersant, stir at 500-800 r / min for 2-3 h to obtain a heating slurry; S2. Spray the conductive adhesive on the mica plate, then adhere the electrode material to obtain a mica plate substrate; S3. Spray the heating slurry on the mica plate substrate, and then heat press and cure to obtain a heating material; The composite graphene heating powder is obtained by adhering a composite layered material to the surface of carbon fibers through polydopamine, and then mixing and reacting with tannic acid and carbon nanotubes; The composite layered material is obtained by synthesizing nanocarbon dots on the surface of silver nanosheets, and then intercalating graphene oxide.

2. The method for preparing a graphene-based heating material according to claim 1, characterized in that, The composite graphene heating powder is specifically prepared by the following steps: A1. Add monohydrate citric acid to deionized water, stir until completely dissolved, adjust the pH, then add silver nanosheets, stir until uniform, and then place in a reaction kettle and react at 170-190℃ for 5-6 h, cool to room temperature, filter, wash and dry to obtain silver nanosheets loaded with carbon dots; A2. Add graphene oxide and silver nanosheets loaded with carbon dots to deionized water, ultrasonic treatment, then filter, wash and dry to obtain a composite layered material; A3. Add carbon fibers to Tris-HCl buffer solution, stir until uniform, add dopamine, stir and react, then filter, wash and dry to obtain polydopamine modified carbon fibers; A4. Add polydopamine modified carbon fibers and composite layered material to deionized water, stir, stand, then filter, wash and dry to obtain modified carbon fibers; A5. Add tannic acid to ethanol, stir until completely dissolved, add carbon nanotubes, stir and react, then add modified carbon fibers, continue to stir and react, filter, wash and dry to obtain a composite graphene heating powder.

3. The method for preparing a graphene-based heating material according to claim 2, characterized in that, In step A1, the amount ratio of monohydrate citric acid, deionized water and silver nanosheets is (2-3) g:(45-55) mL:(3.2-3.4) g.

4. The method for preparing a graphene-based heating material according to claim 2, characterized in that, In step A2, the amount ratio of graphene oxide, silver nanosheets loaded with carbon dots and deionized water is (1.1-1.5) g:(0.8-1.2) g:(75-85) mL.

5. The method for preparing a graphene-based heating material according to claim 2, characterized in that, In step A3, the amount ratio of carbon fibers, Tris-HCl buffer solution and dopamine is (2.1-2.5) g:(45-55) mL:(0.1-0.3) g.

6. The method of claim 2, wherein the graphene-based heating material is prepared by the steps of: preparing a graphene oxide solution; preparing a graphene oxide film by coating the graphene oxide solution on a substrate; and reducing the graphene oxide film to prepare the graphene-based heating material. In step A4, the amount ratio of polydopamine modified carbon fibers, composite layered material and deionized water is (2.5-2.7) g:(1.4-1.6) g:(85-95) mL.

7. The method of claim 2, wherein the graphene-based heating material is prepared by the steps of: preparing a graphene oxide solution; preparing a graphene oxide film by spin coating the graphene oxide solution on a substrate; and reducing the graphene oxide film to prepare the graphene-based heating material. In step A5, the amount ratio of tannic acid, ethanol, carbon nanotubes and modified carbon fibers is (0.6-1) g:(45-55) mL:(0.8-1.2) g:(2.5-2.7) g.

8. The method of claim 1, wherein the graphene-based heating material is prepared by the steps of: preparing a graphene oxide solution; preparing a graphene oxide film by spin coating the graphene oxide solution on a substrate; and reducing the graphene oxide film to prepare the graphene-based heating material. In step S1, the mass ratio of binder, solvent, composite graphene heating powder, stabilizer and dispersant is (25-35):(35-40):(30-40):(1-2):(2-3).

9. The method for preparing a graphene-based heating material according to claim 1, characterized in that, In step S2, the conductive glue is sprayed on the mica plate at a spraying amount of 0.8-1.2 mg / cm 2 and a spraying pressure of 0.25-0.35 MPa. In step S3, the amount of the heat-generating paste sprayed on the mica plate substrate is 2.8-3.5 mg / cm 2 , and the spraying pressure is 0.3-0.4 MPa.

10. A heat generating material prepared by the method of any one of claims 1 to 9.

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