Graphene electric heating material and preparation method thereof

Abstract

The invention provides a graphene electric heating material and a preparation method thereof, and belongs to the field of electric heating materials, the graphene electric heating material is prepared from slurry, a carrier material and an electrode; wherein the slurry is prepared from the following components in percentage by mass: 20-80% of electric heating powder, 50-70% of a binder, 0-5% of a stabilizer and 0-5% of a dispersing agent; wherein the electric heating powder is prepared by mixing 80%-90% by mass of nano graphite carbon powder and 5%-20% by mass of graphene; the graphene electric heating material prepared by the specific preparation method disclosed by the invention has high electric heating conversion rate and high far infrared method phase emissivity, is an electric heating material which is most suitable for far infrared wavelength of a human body, and has the electric heating conversion rate higher than 96%; the phase emissivity of the far infrared method reaches 70% or above, the energy-saving effect is very obvious, energy consumption can be reduced, energy saving is achieved, and industrialization is easy.

Description

Technical Field

[0001] The present invention relates to the field of electric heating materials, and in particular to a graphene electric heating material and a preparation method thereof. Background Art

[0002] Electric heating materials have existed since the invention of electricity. Currently, the widely used electric heating materials mainly include metal resistance electric heating materials (metal resistance wire, etc.) and non-metal resistance electric heating materials (graphite rods, graphite cloth, etc.). Electric heating materials always develop towards energy saving, simple production, wide application range, good far-infrared effect, one refers to the high far-infrared phase emissivity, the other refers to the far-infrared wavelength closest to the most suitable wavelength range for the human body (4-14um), and the goal of extending the service life. The energy saving and far-infrared effect of the material are the parameters that people are most concerned about heating materials. In recent years, people have developed a variety of electric heating material products using graphite materials (graphite fibers, graphite rods, etc.), such as graphite electric heating films, graphite electric heating tubes, etc. This kind of electric heating material generally has a higher electric heat conversion rate, a longer service life than ordinary electric heating materials, and a relatively simple preparation method. At present, the products have been widely used. Graphite electric heating materials have become an important type of electric heating materials and are an important direction for the development of electric heating materials.

[0003] Judging from the current situation of graphite electric heating materials, there are mainly three categories: one is graphite electric heating film material, the second is graphite fiber heating material, and the third is integral graphite heating materials such as graphite sheets and graphite rods. The graphite electric heating film materials currently used have a high electric heat conversion rate (generally greater than 90%), good far-infrared effect (normal phase emissivity is generally 50%-70%), good flexibility, and are thin, but have a low operating temperature, which is generally below 100°C; for graphite fiber heating materials, the electric heat conversion rate is relatively high (85%-90%), the far-infrared effect is good (normal phase emissivity is generally 300%-50%), the softness is good, the thinness is thin, and the heating temperature range is relatively wide (below 800°C), which is currently a widely used electric heating material; for integral graphite heating materials such as graphite sheets and graphite rods, the heating temperature is relatively high (can reach 1200°C), and the production is convenient, but the electric heat conversion rate is relatively low (generally less than 70%), the far-infrared effect is relatively poor, and it is fragile. It is currently mainly used in large heating equipment (such as furnaces, heat treatment furnaces, etc.).

[0004] The present invention provides a graphene electric heating material and a preparation method thereof, which has an extremely high electric heat conversion rate (above 96%), a high far-infrared phase emissivity (above 70%), a far-infrared wavelength suitable for the human body (1-14un), a simple preparation method, and an electric heating material with a wide use temperature range (normal temperature - 1000°C). The material is widely used in various household appliances and other products, and solves the deficiencies and shortcomings of the prior art. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention proposes a graphene electric heating material and a preparation method thereof, which has the characteristics of high electric heat conversion rate and high far-infrared phase emissivity, can reduce energy consumption and achieve energy conservation and emission reduction.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A graphene electric heating material, wherein the graphene electric heating material is made of slurry, a carrier material and an electrode;

[0008] Wherein, the slurry comprises the following raw materials in percentage by mass:

[0009] Electric heating powder 20-80%, binder 50%-70%, stabilizer 0-5%, dispersant 0-5%;

[0010] The electric heating powder is prepared by mixing 80%-90% by mass of nano graphite carbon powder and 5%-20% by mass of graphene.

[0011] Preferably, the slurry comprises the following raw materials in parts by weight: 30-65% of electric heating powder, 55%-65% of binder, 0-3% of stabilizer, and 0-3% of dispersant.

[0012] Preferably, the slurry comprises the following raw materials in parts by weight: 40% electric heating powder, 58% binder, 1% stabilizer, and 1% dispersant.

[0013] Preferably, the carrier material is a ceramic plate or a quartz glass plate; the electrode is pure copper with a thickness of 2 mm×1.5 cm×10 cm.

[0014] Preferably, the graphene is a single-layer graphene, the diameter of the single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0015] Preferably, the nano graphite carbon powder is 40b2 graphite powder.

[0016] Preferably, the stabilizer is silicon dioxide or titanium dioxide, and the particle size of the silicon dioxide or titanium dioxide is 10-300 μm.

[0017] Preferably, the dispersant is a water-based graphene dispersion of model NACO-GC-01.

[0018] Preferably, the binder is high temperature phenolic resin or organic silica gel.

[0019] Preferably, the method for preparing the graphene electric heating material comprises the following steps:

[0020] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0021] (2) Preparation of slurry: dilute the binder with a diluent, add the above-mentioned electric heating powder and dispersant and disperse for 1-2 hours, then add quartz powder to adjust the resistance of the mixture, and disperse for another 0.5-1 hour. Then, put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled continuously for 3-4 times. After rolling, put it into a disperser and disperse it for 0.5-1 hour. Add a diluent during each dispersion and rolling to adjust the viscosity of the mixture to obtain a slurry;

[0022] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0023] (4) Preparation of electric heating plate: The prepared slurry is evenly coated on the carrier material by a coating machine, firstly dried at 45-55°C for 0.5-1h, then dried at 95-105°C for 0.5-1h, and finally dried at 290-310°C for 1-1.5h;

[0024] (5) Preparation of graphene electric heating material: The electric heating plate is placed in a high temperature and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0025] Preferably, the amount of quartz powder added in step (2) is 7.5-20% of the mass of the electric heating powder.

[0026] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] (1) The present invention uses graphene and nanographite powder as the basic materials of the electric heating material, and the prepared electric heating material has the characteristics of high electric heat conversion rate and high far-infrared phase emissivity, and is most suitable for the far-infrared wavelength of the human body;

[0028] (2) The graphene electric heating material of the present invention has excellent electric heat conversion performance, and the electric heat conversion rate is higher than 96%; the far-infrared phase emissivity of the far-infrared wavelength of 2-18um of the present invention reaches more than 70%; the maximum use temperature of the electric heating material of the present invention is up to 1078°C, and the medium temperature type can reach 315°C;

[0029] (3) The preparation process of the electric heating material of the present invention is simple, which not only has a very obvious power saving effect, but also can reduce energy consumption, achieve energy saving, and is easy to industrialize. DETAILED DESCRIPTION

[0030] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Examples 1-5 are for preparing high-temperature graphene electric heating materials, and Examples 6-7 are for preparing medium-temperature graphene electric heating materials.

[0032] Ceramic plates are used as carrier materials for high-temperature electric heating materials, while quartz glass plates are used as carrier materials for medium-temperature electric heating materials.

[0033] The amount of quartz powder added is determined according to the use temperature of the electric heating material and the amount of the electric heating powder. Specifically, the amount of quartz powder added is 12.5-20% of the mass of the electric heating powder. The conductive adhesive is high temperature resistant conductive adhesive HR-8767.

[0034] The adhesive must be able to withstand the temperature range of product use. The high-temperature product is above 1000℃, and the high-temperature graphene electric heating material uses high-temperature phenolic resin as the adhesive (operating temperature 1100℃); the medium-temperature temperature range is about 300℃, and the medium-temperature graphene electric heating material uses organic silicone (two-component organic silicone) as the adhesive (operating temperature 350℃); the diluent for diluting the adhesive is acetone or toluene.

[0035] Embodiment 1:

[0036] The graphene electric heating material of this embodiment 1 is made of slurry, carrier material and electrode (the carrier material is a ceramic plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0037] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0038] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0039] (2) Preparation of slurry:

[0040] Among them, the raw material table for preparing the slurry is:

[0041]

[0042] The electric heating powder is prepared by mixing 85% of nano graphite carbon powder and 15% of graphene in terms of mass percentage.

[0043] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0044] The particle size of silicon dioxide is 10-300 μm.

[0045] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 1.5 hours, then add quartz powder (accounting for 20% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 1 hour, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled 4 times continuously, and then put it into a disperser for dispersion for 1 hour. Add a diluent to adjust the viscosity of the mixture during each dispersion and rolling to obtain a slurry;

[0046] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0047] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 50°C for 1 hour, then keep it warm and dry it at 100°C for 1 hour, and finally keep it warm and dry it at 300°C for 1 hour. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating not cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0048] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the high temperature graphene electric heating material is set to 1000° C. in this embodiment 1) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0049] Embodiment 2:

[0050] The graphene electric heating material of this embodiment 2 is made of slurry, carrier material and electrode (the carrier material is a ceramic plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0051] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0052] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0053] (2) Preparation of slurry:

[0054] Among them, the raw material table for preparing the slurry is:

[0055]

[0056] The electric heating powder is prepared by mixing 80% of nano graphite carbon powder and 20% of graphene in terms of mass percentage.

[0057] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0058] The particle size of titanium dioxide is 10-300 μm.

[0059] First, the binder is diluted with a diluent, and then the above-mentioned electric heating powder and dispersant are added and dispersed for 1 hour, and then quartz powder (accounting for 20% of the mass of the electric heating powder) is added to adjust the resistance of the mixture, and then dispersed for 1 hour, and then the dispersed mixture is put into a three-roller machine for rolling. The three-roller machine needs to be rolled 4 times continuously, and then put into a disperser for dispersion for 1 hour. The diluent is added in each dispersion and rolling to adjust the viscosity of the mixture to obtain a slurry;

[0060] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0061] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 55°C for 1 hour, then keep it warm and dry it at 105°C for 1 hour, and finally keep it warm and dry it at 310°C for 1.5 hours. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating not cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0062] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the high temperature graphene electric heating material is set to 1000° C. in this embodiment 2) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0063] Embodiment 3:

[0064] The graphene electric heating material of this embodiment 3 is made of slurry, carrier material and electrode (the carrier material is a ceramic plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0065] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0066] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0067] (2) Preparation of slurry:

[0068] Among them, the raw material table for preparing the slurry is:

[0069]

[0070] The electric heating powder is prepared by mixing 80% of nano graphite carbon powder and 20% of graphene in mass percentage.

[0071] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0072] The particle size of silicon dioxide is 10-300 μm.

[0073] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 2 hours, then add quartz powder (accounting for 20% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 0.5 hours, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled continuously for 3 times, and then put it into a disperser for dispersion for 1 hour. In each dispersion and rolling, add a diluent to adjust the viscosity of the mixture to obtain a slurry;

[0074] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0075] (4) Preparation of electric heating plate: The prepared slurry is evenly coated on the carrier material by a coating machine, firstly dried at 45°C for 0.5 h, then dried at 95°C for 0.5 h, and finally dried at 290°C for 1 h;

[0076] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the high temperature graphene electric heating material is set to 1000° C. in this embodiment 3) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0077] Embodiment 4:

[0078] The graphene electric heating material of this embodiment 4 is made of slurry, carrier material and electrode (the carrier material is a ceramic plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0079] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0080] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0081] (2) Preparation of slurry:

[0082] Among them, the raw material table for preparing the slurry is:

[0083]

[0084] The electric heating powder is prepared by mixing 90% of nano graphite carbon powder and 10% of graphene in terms of mass percentage.

[0085] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0086] The particle size of titanium dioxide is 10-300 μm.

[0087] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 2 hours, then add quartz powder (accounting for 20% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 1 hour, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled 4 times continuously, and then put it into a disperser for dispersion for 1 hour. In each dispersion and rolling, add a diluent to adjust the viscosity of the mixture to obtain a slurry;

[0088] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0089] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 55°C for 1 hour, then keep it warm and dry it at 95°C for 1 hour, and finally keep it warm and dry it at 310°C for 1.5 hours. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating not cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0090] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the high temperature graphene electric heating material is set to 1000° C. in this embodiment 4) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0091] Embodiment 5:

[0092] The graphene electric heating material of this embodiment 5 is made of slurry, carrier material and electrode (the carrier material is a ceramic plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0093] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0094] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0095] (2) Preparation of slurry:

[0096] Among them, the raw material table for preparing the slurry is:

[0097]

[0098]

[0099] The electric heating powder is prepared by mixing 80% of nano graphite carbon powder and 20% of graphene in mass percentage.

[0100] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0101] The particle size of silicon dioxide is 10-300 μm.

[0102] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 1 hour, then add quartz powder (accounting for 20% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 0.5 hours, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled continuously for 3 times, and then put it into a disperser for 0.5 hours after rolling. Add a diluent to adjust the viscosity of the mixture during each dispersion and rolling to obtain a slurry;

[0103] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0104] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 45°C for 0.5h, then keep it warm and dry it at 95°C for 1h, and finally keep it warm and dry it at 305°C for 1.5h. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating not cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0105] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the high temperature graphene electric heating material is set to 1000° C. in this embodiment 5) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0106] Embodiment 6:

[0107] The graphene electric heating material of this embodiment 6 is made of slurry, carrier material and electrode (the carrier material is a quartz glass plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0108] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0109] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0110] (2) Preparation of slurry:

[0111] Among them, the raw material table for preparing the slurry is:

[0112]

[0113] The electric heating powder is prepared by mixing 80% of nano graphite carbon powder and 20% of graphene in mass percentage.

[0114] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0115] The particle size of silicon dioxide is 10-300 μm.

[0116] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 1.5 hours, then add quartz powder (accounting for 7.5% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 1 hour, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled 4 times continuously, and then put it into a disperser for dispersion for 1 hour. Add a diluent to adjust the viscosity of the mixture during each dispersion and rolling to obtain a slurry;

[0117] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0118] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 45-55℃ for 0.5-1h, then keep it warm and dry it at 95-105℃ for 0.5-1h, and finally keep it warm and dry it at 290-310℃ for 1-1.5h. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating without cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0119] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the medium temperature graphene electric heating material is set to 300° C. in this embodiment 6) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0120] Embodiment 7:

[0121] The graphene electric heating material of this embodiment 7 is made of slurry, carrier material and electrode (the carrier material is a quartz glass plate; the electrode is pure copper with a thickness of 2mm×1.5cm×10cm);

[0122] The method for preparing the graphene electric heating material specifically comprises the following steps:

[0123] (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder;

[0124] (2) Preparation of slurry:

[0125] Among them, the raw material table for preparing the slurry is:

[0126]

[0127]

[0128] The electric heating powder is prepared by mixing 80% of nano graphite carbon powder and 20% of graphene in mass percentage.

[0129] The diameter of a single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

[0130] The particle size of silicon dioxide is 10-300 μm.

[0131] First, dilute the binder with a diluent, then add the above-mentioned electric heating powder and dispersant and disperse for 1-2 hours, then add quartz powder (accounting for 10% of the mass of the electric heating powder) to adjust the resistance of the mixture, and then disperse for 0.5-1 hour, and then put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled continuously for 3-4 times, and then put it into a disperser for 0.5-1 hour after rolling. Add a diluent to adjust the viscosity of the mixture during each dispersion and rolling to obtain a slurry;

[0132] (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive;

[0133] (4) Production of electric heating plate: Use a coating machine to evenly coat the prepared slurry on the carrier material, first keep it warm and dry it at 45-55℃ for 0.5-1h, then keep it warm and dry it at 95-105℃ for 0.5-1h, and finally keep it warm and dry it at 290-310℃ for 1-1.5h. During the drying process, pay attention to the surface conditions at all times to prevent cracking and other phenomena. If cracking and other phenomena are found, adjust the coating and drying process parameters at any time. The thickness of each coating shall be based on the coating without cracking. The coating thickness is determined according to the required heating temperature of the electric heating material (a comparison table of material coating thickness, resistance, and heating temperature obtained from existing laboratories). If the required resistance cannot be achieved by one coating, it can be coated multiple times until the specified resistance is reached;

[0134] (5) Preparation of graphene electric heating material: The above electric heating plate is placed in the highest use temperature (the medium temperature graphene electric heating material is set at 300° C. in this embodiment 7) and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

[0135] The graphene electric heating materials prepared in Examples 1-7 were tested by an infrared detector, and the far-infrared normal phase emissivity of the far-infrared light of the graphene electric heating materials at a wavelength of 2-18 μm was determined; the electrothermal conversion rate of the graphene electric heating materials and the maximum temperature at which the graphene electric heating materials can be used were calculated.

[0136] Table 1: Performance test data statistics of graphene electric heating materials of Examples 1-7:

[0137]

[0138] Based on the above, we can get:

[0139] (1) The graphene electric heating material prepared in this embodiment has an electric heat conversion rate greater than 95%, which is higher than the existing carbon fiber heating material;

[0140] (2) At the same time, the present invention also enhances the far-infrared phase emissivity of the graphene electric heating material, and its far-infrared phase emissivity can reach a maximum of 81.5%, so that the far-infrared wavelength of the graphene electric heating material reaches (2um-18um), which is the best wavelength range for human health care;

[0141] (3) This embodiment can prepare graphene electric heating materials suitable for room temperature to 315°C, and can also prepare graphene electric heating materials suitable for room temperature to 1000°C, which are widely used in various household appliances and other products.

[0142] Comparative Example 1:

[0143] The graphene electric heating material of this comparative example 1 was prepared using the same raw materials and steps as those of Example 5, with the only difference being that no stabilizer and dispersant were added in this comparative example 1.

[0144] Among them, the raw material table for preparing the slurry is:

[0145]

[0146] The graphene electric heating material finally prepared has the best electric heating performance of nano-graphite carbon powder (10-100nm), but it is difficult to disperse and is prone to agglomeration, thus losing the nano effect (loss of electric heating performance).

[0147] Comparative Example 2

[0148] The raw materials used in preparing the slurry in this comparative example 2 are as follows:

[0149] The raw material list of the slurry is:

[0150]

[0151] In this comparative example 2, nano graphite powder is replaced by micro graphite powder (10-300um) material. The electrothermal performance of micro graphite powder (10-300um) material is better (inferior to nano graphite powder), but the dispersibility is good, no agglomeration phenomenon is found, and the electrical performance is stable.

[0152] Comparative Example 3

[0153] The graphene electric heating material of this comparative example 3 was prepared using the same raw materials and steps as those of Example 5, with the only difference being:

[0154] 1. No stabilizer or dispersant was added in this comparative example 3.

[0155] 2. Nano-graphite carbon powder is replaced by micro-graphite carbon powder

[0156] The raw materials used in preparing the slurry in this comparative example 3 are as follows:

[0157] The raw material list of the slurry is:

[0158]

[0159] Table 2: Performance test data statistics of graphene electric heating materials prepared in Comparative Examples 1-3:

[0160]

[0161] In summary:

[0162] (1) It can be concluded from Example 5 and Comparative Examples 1-3 that the addition of dispersants and stabilizers can prevent graphene from agglomerating, increase the electrical and temperature properties of the graphene electric heating material, and improve the electric heat conversion rate.

[0163] (2) It can be concluded from the examples and comparative examples that the specific amount of quartz powder added can greatly affect the final resistance of the slurry, and then affect the maximum operating temperature of the graphene electric heating material.

[0164] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0165] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A graphene electric heating material, characterized in that: The graphene electric heating material is made of slurry, carrier material and electrodes; Wherein, the slurry comprises the following raw materials in percentage by mass: Electric heating powder 20-80%, binder 50%-70%, stabilizer 0-5%, dispersant 0-5%; The electric heating powder is prepared by mixing 80%-90% by mass of nano graphite carbon powder and 5%-20% by mass of graphene.

2. The graphene electric heating material according to claim 1, characterized in that: The slurry comprises the following parts by weight in the raw material preparation: Electric heating powder 30-65%, binder 55%-65%, stabilizer 0-3%, dispersant 0-3%.

3. The graphene electric heating material according to claim 2, characterized in that: The slurry comprises the following parts by weight in the raw material preparation: Electric heating powder 40%, binder 58%, stabilizer 1%, dispersant 1%.

4. The graphene electric heating material according to claim 1, characterized in that: The carrier material is a ceramic plate or a quartz glass plate; the electrode is pure copper with a thickness of 2 mm×1.5 cm×10 cm.

5. The graphene electric heating material according to claim 1, characterized in that: The graphene is a single-layer graphene, the diameter of the single-layer graphene is 0.5-5 μm, the thickness is 0.8-1 nm, the purity of the graphene is greater than 99%, and the single-layer rate is greater than 80%.

6. The graphene electric heating material according to claim 1, characterized in that: The nano graphite carbon powder is 40b2 graphite powder.

7. The graphene electric heating material according to claim 1, characterized in that: The stabilizer is silicon dioxide or titanium dioxide, and the particle size of the silicon dioxide or titanium dioxide is 10-300 μm.

8. The graphene electric heating material according to claim 1, characterized in that: The dispersant is a water-based graphene dispersion of model NACO-GC-01; the binder is a high-temperature phenolic resin or organic silica gel.

9. The method for preparing the graphene electric heating material according to any one of claims 1 to 8, characterized in that: The method specifically includes the following steps: (1) Preparation of electric heating powder: First, nano graphite carbon powder and graphene are mixed and mixed evenly by a blender to prepare electric heating powder; (2) Preparation of slurry: dilute the binder with a diluent, add the above-mentioned electric heating powder, dispersant and stabilizer to disperse for 1-2 hours, then add quartz powder to adjust the resistance of the mixture, and disperse for another 0.5-1 hour. Then, put the dispersed mixture into a three-roller machine for rolling. The three-roller machine needs to be rolled continuously for 3-4 times. After rolling, put it into a disperser and disperse it for 0.5-1 hour. Add a diluent during each dispersion and rolling to adjust the viscosity of the mixture to obtain a slurry; (3) Connecting the carrier material and the electrode: fix the electrode at the center of the upper end of the carrier material and bond it with a conductive adhesive; (4) Preparation of electric heating plate: The prepared slurry is evenly coated on the carrier material by a coating machine, firstly dried at 45-55°C for 0.5-1h, then dried at 95-105°C for 0.5-1h, and finally dried at 290-310°C for 1-1.5h; (5) Preparation of graphene electric heating material: The electric heating plate is placed in a high temperature and kept at this temperature for 3 hours for stabilization treatment to obtain the graphene electric heating material.

10. The method for preparing the graphene electric heating material according to claim 9, characterized in that: The amount of quartz powder added in step (2) is 7.5-20% of the mass of the electric heating powder.

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