Heating film, method and heat pump for heating and drying smoke tea based on graphene far infrared rays

Abstract

The invention discloses a heating film and method for heating and drying smoke tea based on graphene far infrared and a heat pump. The heating film comprises a flexible substrate layer, a flexible substrate layer, a flexible substrate layer and a flexible substrate layer which are sequentially arranged from inside to outside, wherein the flexible substrate layer is composed of a polyimide film, the thickness of the flexible substrate layer is 0.1-0.3 mm, and the surface of the flexible substrate layer is provided with a micropore structure; the composite conductive layer is formed by compounding graphene powder and silver nanowires according to the mass ratio of (2-4): 1, and the thickness of the composite conductive layer is 0.02-0.05 mm; the heat-conducting insulating layer is composed of a mixed material of boron nitride nanosheets and polyethylene, and the thickness of the heat-conducting insulating layer is 0.1-0.2 mm; the reflection shielding layer is formed by compounding aluminum foil and polyethylene glycol terephthalate, and the thickness of the reflection shielding layer is 0.05-0.1 mm; the protective coating is composed of fluorinated modified organic silicon resin, and the thickness of the protective coating is 0.01-0.03 mm. The graphene foam heating film has the advantages that the core problems that a traditional heating film is uneven in heat distribution, low in energy efficiency and short in service life are solved, and the graphene foam heating film can be prepared by adjusting the porosity of the graphene foam, the thickness of the conductive layer and other parameters. Various requirements of tobacco leaf drying (high temperature and high humidity), low-temperature dehydration of tea leaves, industrial rapid heating and the like can be met, and the expansibility is high.

Description

Technical Field

[0001] The present invention relates to the technical field of heating films, and particularly to a heating film for far-infrared heating and drying of tobacco tea based on graphene, a manufacturing method of the heating film, and an air heat pump. Background Art

[0002] Most of the existing far-infrared heating films use a single conductive material (such as graphene or carbon fiber) as the heating element. Although they can meet certain usage requirements, there are certain deficiencies. For example, the heating efficiency is limited by the material singularity, and local overheating or performance attenuation is likely to occur after long-term use; the traditional insulating layer (such as PE) has poor thermal conductivity, and the heat transfer is uneven, affecting the overall energy efficiency; the preparation process is complex, and multi-layer coating is likely to lead to insufficient interfacial bonding force, affecting the durability of the product. Therefore, there is an urgent need for a far-infrared heating film with high efficiency, stability, and versatility to solve the deficiencies of the existing heating films. Summary of the Invention

[0003] In order to overcome the existing technical defects, the purpose of the present invention is to provide a heating film for far-infrared heating and drying of tobacco tea based on graphene, a manufacturing method of the heating film, and an air heat pump to solve the above technical problems.

[0004] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0005] According to one aspect of the present invention, a heating film for far-infrared heating and drying of tobacco tea ingredients is designed, including, from inside to outside in sequence:

[0006] A flexible base layer, composed of a polyimide film, with a thickness of 0.1 - 0.3 mm and a microporous structure on the surface;

[0007] A composite conductive layer, composed of graphene powder and silver nanowires compounded in a mass ratio of 2 - 4:1, with a thickness of 0.02 - 0.05 mm;

[0008] A thermally conductive insulating layer, composed of a mixture of boron nitride nanosheets and polyethylene, with a thickness of 0.1 - 0.2 mm;

[0009] A reflection shielding layer, composed of a composite of aluminum foil and polyethylene terephthalate, with a thickness of 0.05 - 0.1 mm;

[0010] A protective coating, composed of a fluorinated modified silicone resin, with a thickness of 0.01 - 0.03 mm.

[0011] In order to better solve the above technical defects, the present invention also has a better technical solution:

[0012] In some embodiments, it further includes a graphene foam thermal conductivity enhancement layer, which is composed of three-dimensional porous graphene foam with a thickness of 0.1 - 0.3 mm, and is disposed between the thermal insulation layer and the reflection shielding layer.

[0013] In some embodiments, the mass ratio of the graphene powder to the silver nanowires is 3:1, the thickness of the composite conductive layer is 0.03 mm, and the micropore diameter is 50 - 200 nm.

[0014] In some embodiments, the porosity of the graphene foam thermal conductivity enhancement layer is 80 - 95%, the pore diameter is 10 - 200 μm, and the surface is treated by nitrogen doping.

[0015] In some embodiments, the thickness of the flexible base layer is 0.2 mm, and the thickness of the thermal insulation layer is 0.15 mm.

[0016] In some embodiments, the thickness of the reflection shielding layer is 0.07 mm, and the thickness of the protective coating is 0.02 mm.

[0017] In some embodiments, the mass percentage of the boron nitride nanosheets in the boron nitride nanosheet and polyethylene composite material is 15% - 30%.

[0018] In some embodiments, the particle size of the boron nitride nanosheets is 100 - 500 nm.

[0019] According to another aspect of the present invention, a method for manufacturing a heating film based on the above heating film structure is designed, including the following steps:

[0020] S1. Pretreatment of the flexible base layer: Cut a polyimide film with a thickness of 0.1 - 0.3 mm into the required size, place it in a vacuum plasma processing equipment, introduce a mixed gas of argon and oxygen, control the gas flow rate to be 20 - 30 sccm, the chamber pressure to be 10 - 50 Pa, turn on the radio frequency power supply, set the power to 200 - 300 W, and process for 5 - 10 minutes to form a uniform microporous structure with a pore diameter of 50 - 200 nm on the surface of the flexible base layer;

[0021] S2. Preparation of the composite conductive layer: Add graphene powder and silver nanowires in a mass ratio of 2 - 4:1 to an N-methylpyrrolidone solvent, control the solid content to be 5% - 8%, disperse with an ultrasonic cell disruptor for 30 - 45 minutes to obtain a homogeneous slurry, use a slot coater to coat the slurry on the surface of the flexible base layer, and pre-cure in a hot air circulation oven at 80 - 100 °C for 10 - 15 minutes to form a composite conductive layer with a thickness of 0.02 - 0.05 mm;

[0022] S3. Coating the thermally conductive insulating layer: Mix boron nitride nanosheets and molten polyethylene at a mass ratio of 15% - 30%, stir at a temperature of 180 - 200 °C and a stirring rate of 300 - 500 rpm. The particle size of the boron nitride nanosheets is 100 - 500 nm. Use an electrostatic spraying device to evenly spray the mixed material on the surface of the composite conductive layer. After cooling to room temperature, a thermally conductive insulating layer with a thickness of 0.1 - 0.2 mm is formed.

[0023] S4. Compositing the graphene foam layer: Cut the graphene foam sheet with a thickness of 0.1 - 0.3 mm to the required size, and then attach it to the surface of the thermally conductive insulating layer through a hot pressing process.

[0024] S5. Compositing the reflective shielding layer: Align and stack the aluminum foil and the PET film. The thickness of the aluminum foil is 0.02 - 0.05 mm, and the thickness of the PET film is 0.03 - 0.05 mm. Then place them in a hot press, set the temperature at 150 - 180 °C and the pressure at 5 - 8 MPa, and hold the pressure for 20 - 40 seconds to completely bond the two layers of materials. After cutting, attach it to the surface of the graphene foam layer, and the edge is treated with laser edge sealing.

[0025] S6. Curing the protective coating: Spray the fluorinated modified silicone resin on the surface of the reflective shielding layer, place it in an ultraviolet curing machine with a wavelength of 365 nm and a light intensity of 50 - 80 mW / cm 2 , and cure for 20 - 30 seconds to form a protective coating with a thickness of 0.01 - 0.03 mm.

[0026] In some embodiments, the volume ratio of argon to oxygen in step S1 is 4:1, and the mass ratio of graphene powder to silver nanowires in step S2 is 3:1.

[0027] According to another aspect of the present invention, an air heat pump based on the above-mentioned heating film is designed, including: a box body, a blowing fan, and a plurality of heating film blocks. An air inlet is provided at the right end of the box body, and an air outlet is provided at the left end. The blowing fan is installed in the air inlet, and a plurality of heating modules are longitudinally and parallelly installed at intervals in the box body.

[0028] In summary, the beneficial effects of the present invention are as follows: The graphene powder and silver nanowires are composited in a specific ratio, taking into account high electrical conductivity and flexibility, breaking through the performance bottleneck of single materials. Through the multi-level thermal management design of the plasma microporous substrate, graphene / silver nanowire composite conductive layer, boron nitride thermal conductive layer and graphene foam layer, the core problems of uneven thermal distribution, low energy efficiency and short life of traditional heating films are systematically solved. By adjusting parameters such as the porosity of the graphene foam and the thickness of the conductive layer, it can be adapted to various requirements such as tobacco leaf drying (high temperature and high humidity), low-temperature dehydration of tea leaves, and industrial rapid heating, with strong scalability. Description of the Drawings

[0029] Figure 1Schematic diagram of a heating film structure for drying tobacco and tea ingredients based on graphene far-infrared heating provided by the present invention;

[0030] Figure 2 Schematic diagram of an air heat pump structure provided by the present invention;

[0031] Figure 3 For Figure 2 Schematic diagram of another perspective;

[0032] Reference numerals:

[0033] 1, flexible base layer; 2, composite conductive layer; 3, thermal insulation layer; 4, graphene foam thermal conductivity enhancement layer; 5, reflection shielding layer; 6, protective coating; 7, box body; 71, air inlet; 72, air outlet; 8, air supply fan; 9, heating film block. Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0035] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by terms such as up, down, front, back, left, right, etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installation, connection, and fixing should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0037] Example 1

[0038] Referring to Figure 1 as shown, the heating film for drying tobacco and tea ingredients based on graphene far-infrared heating provided by the present invention includes, from inside to outside in sequence: a flexible base layer 1, a composite conductive layer 2, a thermal insulation layer 3, a graphene foam thermal conductivity enhancement layer 4, a reflection shielding layer 5, and a protective coating 6.

[0039] The flexible base layer 1 is composed of a polyimide film with a thickness of 0.1 - 0.3 mm, and its thickness is 0.1 mm or 0.2 mm or 0.3 mm. The surface is treated by plasma to form a microporous structure with a pore diameter of 50 - 200 nm, and the micropore diameter is 50 nm or 100 nm or 150 nm or 200 nm.

[0040] The composite conductive layer 2 is composed of graphene powder and silver nanowires compounded in a mass ratio of 2 - 4:1, with a thickness of 0.02 - 0.05 mm, and its thickness is 0.02 mm or 0.03 mm or 0.04 mm or 0.05 mm. The mass ratio of graphene powder to silver nanowires is 2:1 or 3:1 or 4:1.

[0041] The thermal conductive insulating layer 3 is composed of a mixture of boron nitride nanosheets and polyethylene (PE), with a thickness of 0.1 - 0.2 mm, and the thickness is 0.1 mm or 0.15 mm or 0.2 mm. Among them, the mass proportion of boron nitride nanosheets in the mixture of boron nitride nanosheets and polyethylene (PE) is 15% - 30%, and the mass proportion is 15% or 20% or 25% or 30%. The particle size of boron nitride nanosheets is 100 - 500 nm, and the particle size is 100 nm or 200 nm or 300 nm or 500 nm.

[0042] The graphene foam thermal conductivity enhancement layer 4 is composed of three-dimensional porous graphene foam, with a thickness of 0.1 - 0.3 mm, and the thickness is 0.1 mm or 0.2 mm or 0.3 mm. Its porosity is 80 - 95%, the pore diameter is 10 - 200 μm, and the surface is treated by nitrogen doping with a nitrogen content of 2 - 5% to enhance the interfacial bonding force with the thermal conductive insulating layer.

[0043] The reflective shielding layer 5 is composed of a composite of aluminum foil and polyethylene terephthalate (PET), with a thickness of 0.05 - 0.1 mm, and the thickness is 0.05 mm or 0.07 mm or 0.1 mm.

[0044] The protective coating 6 is composed of fluorinated modified silicone resin, with a thickness of 0.01 - 0.03 mm, and the thickness is 0.01 mm or 0.02 mm or 0.03 mm.

[0045] Setting micropores on the flexible base layer can enhance the bonding strength between the flexible base layer and the composite conductive layer, and there is no delamination phenomenon in the peel test. In addition, the micropores guide the uniform penetration of the conductive paste to ensure heat uniformity. Moreover, the micropores disperse stress, enabling the heating film to have good bending performance and be applicable to curved surface drying equipment. Graphene powder and silver nanowires form a three-dimensional conductive network in proportion to improve conductivity. In addition, the surface temperature of the heating film reaches the target value (such as 60 °C) within 3 seconds after being powered on, which is significantly shorter than that of a pure graphene layer (response time ≥ 8 seconds). Boron nitride nanosheets in the thermally conductive insulating layer form a directional heat conduction path, with a transverse thermal conductivity of 8 - 12 W / m·K, greatly improving the heat conduction effect. The pore structure of the porous graphene foam promotes air flow, which can improve the heat convection efficiency during drying treatment and shorten the drying time. The graphene foam heat conduction enhancement layer can be used to improve the transverse heat diffusion efficiency, making the surface temperature difference ≤ 0.7 °C. The aluminum foil of the reflective shielding layer has a reflectivity ≥ 95%, reflecting the heat energy radiated downward to the dried material, increasing the energy efficiency conversion rate from 85% to ≥ 93%, reducing energy loss, and achieving high energy efficiency.

[0046] Example Two

[0047] A method for manufacturing a heating film based on the heating film of Example One provided by the present invention includes the following steps:

[0048] S1. Pretreatment of the flexible base layer: Cut a polyimide film with a thickness of 0.1 - 0.3 mm into the required size, place it in a vacuum plasma treatment device, introduce a mixed gas of argon and oxygen with a volume ratio of argon to oxygen of 4:1, control the gas flow rate to be 20 - 30 sccm, the chamber pressure to be 10 - 50 Pa, turn on the radio frequency power supply, set the power to 200 - 300 W, and the treatment time to 5 - 10 minutes to form a uniform micropore structure with a pore diameter of 50 - 200 nm on the surface of the flexible base layer.

[0049] S2. Preparation of the composite conductive layer: Add graphene powder and silver nanowires in a mass ratio of 2 - 4:1 to the N-methylpyrrolidone solvent, control the solid content to be 5% - 8%, disperse with an ultrasonic cell disruptor for 30 - 45 minutes to obtain a homogeneous slurry, use a slot coater to coat the slurry on the surface of the flexible base layer, and pre-cure it in a hot air circulation oven at 80 - 100 °C for 10 - 15 minutes to form a composite conductive layer with a thickness of 0.02 - 0.05 mm.

[0050] S3. Coating of the thermally conductive insulating layer: Mix boron nitride nanosheets and molten polyethylene in a mass ratio of 15% - 30%, stir at a temperature of 180 - 200 °C and a stirring rate of 300 - 500 rpm. The particle size of the boron nitride nanosheets is 100 - 500 nm. Use an electrostatic spraying device to uniformly spray the mixed material on the surface of the composite conductive layer, and after cooling to room temperature, form a thermally conductive insulating layer with a thickness of 0.1 - 0.2 mm.

[0051] S4. Graphene foam layer lamination: Cut the graphene foam sheet with a thickness of 0.1 - 0.3 mm into the required size, perform nitrogen doping treatment on the surface, and then laminate it on the surface of the thermal insulation layer through a hot pressing process.

[0052] S5. Reflective shielding layer lamination: Align and stack the aluminum foil and the PET film (polyethylene terephthalate film). The thickness of the aluminum foil is 0.02 - 0.05 mm, and the thickness of the PET film is 0.03 - 0.05 mm. Then place them in a hot press, set the temperature at 150 - 180 °C, the pressure at 5 - 8 MPa, and keep the pressure for 20 - 40 seconds to completely bond the two layers of materials. After that, cut out the appropriate size and laminate it on the surface of the graphene foam layer, and perform laser edge sealing treatment on the edge.

[0053] S6. Protective coating curing: Spray the fluorinated modified silicone resin on the surface of the reflective shielding layer. Spraying can perform plasma cleaning on the surface of the reflective shielding layer to improve the bonding strength. Then place it in an ultraviolet curing machine with a wavelength of 365 nm and a light intensity of 50 - 80 mW / cm 2 , cure for 20 - 30 seconds to form a protective coating with a thickness of 0.01 - 0.03 mm, achieving waterproof and flame - retardant protection.

[0054] Example Three

[0055] A method for manufacturing a heating film based on the heating film of Example One, including the following steps:

[0056] S1. Production of the flexible base layer:

[0057] Material: Polyimide film with a thickness of 0.2 mm, cut into the required size;

[0058] Pretreatment: Place the cut polyimide film in a vacuum plasma treatment device, and introduce a mixed gas of argon and oxygen, with argon:oxygen = 4:1, to perform vacuum plasma treatment. The gas flow rate is 25 sccm, the chamber pressure is 30 Pa, the radio frequency power is 250 W, and the treatment time is 8 minutes, so that uniform micropores with a pore diameter of about 150 nm are formed on the surface of the flexible base layer.

[0059] S2. Preparation of the composite conductive layer:

[0060] Add graphene powder and silver nanowires in a mass ratio of 3:1 (the proportion of silver nanowires is 25%) to the N - methylpyrrolidone solvent, control the content of graphene powder and silver nanowires at 6%, and disperse them for 35 minutes using an ultrasonic cell disruptor at a frequency of 40 kHz to obtain a homogeneous slurry;

[0061] Coating: Use a slot coater to coat the slurry on the surface of the flexible substrate layer, and place it in a hot air circulation oven for pre-curing. The pre-curing temperature is 90 °C and the time is 12 minutes to form a composite conductive layer with a thickness of 0.04 mm.

[0062] S3. Coating of the thermally conductive insulating layer:

[0063] Mix boron nitride nanosheets and molten polyethylene in a mass ratio of 25% (the proportion of boron nitride nanosheets is 25%). The stirring temperature is 190 °C, the stirring rate is 400 rpm, and the particle size of the boron nitride nanosheets is 300 nm. Use an electrostatic spraying device to evenly spray the mixed material on the surface of the composite conductive layer. After cooling to room temperature, a thermally conductive insulating layer with a thickness of 0.18 mm is formed.

[0064] S4. Laminating the graphene foam layer:

[0065] Cut the graphene foam sheet with a thickness of 0.2 mm into the required size. The porosity of the graphene foam sheet is 90%, and the surface is treated by nitrogen doping. Then, laminate it on the surface of the thermally conductive insulating layer through a hot pressing process. The hot pressing temperature is 230 °C, the pressure is 4 MPa. After the hot pressing is completed, the edges are sealed by plasma welding to ensure no gap between layers.

[0066] S5. Laminating the reflective shielding layer;

[0067] Align and stack the aluminum foil and the PET film. The thickness of the aluminum foil is 0.03 mm, and the thickness of the PET film is 0.04 mm. Then place them in a hot press, set the temperature at 170 °C and the pressure at 6 MPa, and hold the pressure for 30 seconds to completely bond the two layers of materials. After lamination, cut out the appropriate size and laminate it on the surface of the graphene foam layer, and the edges are treated by laser sealing.

[0068] S6. Curing the protective coating:

[0069] Spray the fluorinated modified silicone resin on the surface of the reflective shielding layer. The viscosity of the fluorinated modified silicone resin is 600 cps. Then place it in an ultraviolet curing machine. The ultraviolet wavelength is 365 nm, and the light intensity is 60 mW / cm 2 , and cure for 25 seconds to form a protective coating with a thickness of 0.02 mm.

[0070] Apply the prepared heating film to tobacco leaf drying. The performance comparison with the traditional heating film (pure graphene film) applied to tobacco leaf drying is as follows in the table:

[0071]

[0072] The above results are all obtained under the conventional specified test standards.

[0073] Example 4

[0074] A method for manufacturing a heating film based on the heating film of Embodiment 1, comprising the following steps:

[0075] S1. Fabrication of the flexible base layer:

[0076] Material: Polyimide film with a thickness of 0.1 mm, cut into the required size;

[0077] Pretreatment: Place the cut polyimide film in a vacuum plasma treatment device, and introduce a mixed gas of argon and oxygen, argon:oxygen = 4:1, for vacuum plasma treatment. The gas flow rate is 20 sccm, the chamber pressure is 10 Pa, the radio frequency power is 200 W, and the treatment time is 5 minutes, so that uniform micropores with a pore diameter of about 50 nm are formed on the surface of the flexible base layer.

[0078] S2. Preparation of the composite conductive layer:

[0079] Add graphene powder and silver nanowires in a mass ratio of 2:1 to the N-methylpyrrolidone solvent, control the content of graphene powder and silver nanowires at 5%, and disperse for 30 minutes with an ultrasonic cell disruptor at a frequency of 40 kHz to obtain a homogeneous slurry;

[0080] Coating: Use a slot coater to coat the slurry on the surface of the flexible base layer, and place it in a hot air circulation oven for pre-curing. The pre-curing temperature is 80 °C and the time is 10 minutes to form a composite conductive layer with a thickness of 0.02 mm.

[0081] S3. Coating of the thermal insulation layer:

[0082] Mix boron nitride nanosheets and molten polyethylene in a mass ratio of 15% (the proportion of boron nitride nanosheets is 15%), stir at a temperature of 180 °C and a stirring rate of 300 rpm. The particle size of the boron nitride nanosheets is 100 nm. Use an electrostatic spraying device to uniformly spray the mixed material on the surface of the composite conductive layer. After cooling to room temperature, a thermal insulation layer with a thickness of 0.1 mm is formed.

[0083] S4. Lamination of the graphene foam layer:

[0084] Cut a graphene foam sheet with a thickness of 0.1 mm into the required size. The porosity of the graphene foam sheet is 90%, and the surface is treated by nitrogen doping. Then, it is laminated on the surface of the thermal insulation layer through a hot pressing process. The hot pressing temperature is 200 °C, the pressure is 3 MPa. After the hot pressing is completed, the edge is sealed by plasma welding to ensure no gap between layers.

[0085] S5. Lamination of the reflective shielding layer;

[0086] Align and stack the aluminum foil with the PET film. The thickness of the aluminum foil is 0.02 mm, and the thickness of the PET film is 0.03 mm. Then place them in a hot press, set the temperature at 150 °C, the pressure at 5 MPa, and keep the pressure for 20 seconds to completely bond the two layers of materials. After bonding, cut out the appropriate size and bond it to the surface of the graphene foam layer, and the edge is treated with laser sealing.

[0087] S6. Curing of the protective coating:

[0088] Spray the fluorinated modified silicone resin on the surface of the reflective shielding layer. The viscosity of the fluorinated modified silicone resin is 600 cps. Then place it in an ultraviolet curing machine. The ultraviolet wavelength is 365 nm, and the light intensity is 50 mW / cm 2 , and cure for 20 seconds to form a protective coating with a thickness of 0.01 mm.

[0089] Example Five

[0090] A method for manufacturing a heating film based on the heating film of Example One, including the following steps:

[0091] S1. Fabrication of the flexible base layer:

[0092] Material: Polyimide film with a thickness of 0.3 mm, cut into the required size;

[0093] Pretreatment: Place the cut polyimide film in a vacuum plasma treatment device, and introduce a mixed gas of argon and oxygen. The ratio of argon to oxygen is 4:1, and perform vacuum plasma treatment. The gas flow rate is 30 sccm, the chamber pressure is 50 Pa, the radio frequency power is 300 W, and the treatment time is 10 minutes to form uniform micropores with a pore diameter of about 200 nm on the surface of the flexible base layer.

[0094] S2. Preparation of the composite conductive layer:

[0095] Add graphene powder and silver nanowires in a mass ratio of 4:1 to the N-methylpyrrolidone solvent. The content of graphene powder and silver nanowires is controlled at 8%, and disperse for 45 minutes using an ultrasonic cell disruptor at a frequency of 40 kHz to obtain a homogeneous slurry;

[0096] Coating: Use a slot coater to coat the slurry on the surface of the flexible base layer, and place it in a hot air circulation oven for pre-curing. The pre-curing temperature is 100 °C, and the time is 15 minutes to form a composite conductive layer with a thickness of 0.05 mm.

[0097] S3. Coating of the thermal insulation layer:

[0098] Mix boron nitride nanosheets with molten polyethylene at a mass ratio of 30% (boron nitride nanosheets account for 30%), stir at a temperature of 200 °C and a stirring rate of 500 rpm. The particle size of the boron nitride nanosheets is 500 nm. Use an electrostatic spraying device to evenly spray the mixed material on the surface of the composite conductive layer. After cooling to room temperature, a thermal insulation layer with a thickness of 0.2 mm is formed.

[0099] S4. Graphene foam layer composite:

[0100] Cut the graphene foam sheet with a thickness of 0.3 mm into the required size. The porosity of the graphene foam sheet is 90%, and the surface is treated by nitrogen doping. Then, it is laminated on the surface of the thermal insulation layer through a hot pressing process. The hot pressing temperature is 250 °C, the pressure is 5 MPa. After the hot pressing is completed, the edges are sealed by plasma welding to ensure no gap between layers.

[0101] S5. Reflective shielding layer composite;

[0102] Align and stack the aluminum foil and the PET film. The thickness of the aluminum foil is 0.05 mm, and the thickness of the PET film is 0.05 mm. Then, place them in a hot press, set the temperature at 180 °C, the pressure at 8 MPa, and keep the pressure for 40 seconds to completely bond the two layers of materials. After bonding, cut out the appropriate size and laminate it on the surface of the graphene foam layer, and the edges are sealed by laser.

[0103] S6. Protective coating curing:

[0104] Spray the fluorinated modified silicone resin on the surface of the reflective shielding layer. The viscosity of the fluorinated modified silicone resin is 600 cps. Then, place it in an ultraviolet curing machine with an ultraviolet wavelength of 365 nm and a light intensity of 80 mW / cm 2 , and cure for 30 seconds to form a protective coating with a thickness of 0.03 mm.

[0105] Example 6

[0106] Reference Figure 2 , 3 As shown in

[0107] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A heating film for far-infrared heating and drying of tobacco and tea ingredients based on graphene, characterized in that, Comprising, successively arranged from the inside to the outside: A flexible base layer, made of a polyimide film, with a thickness of 0.1 - 0.3 mm, and having a microporous structure on its surface; A composite conductive layer, composed of graphene powder and silver nanowires compounded at a mass ratio of 2 - 4:1, with a thickness of 0.02 - 0.05 mm; A thermal insulation layer, composed of a mixed material of boron nitride nanosheets and polyethylene, with a thickness of 0.1 - 0.2 mm; A reflection shielding layer, composed of a composite of aluminum foil and polyethylene terephthalate, with a thickness of 0.05 - 0.1 mm; A protective coating, composed of a fluorinated modified silicone resin, with a thickness of 0.01 - 0.03 mm.

2. The heating film based on graphene far-infrared heating for drying tobacco and tea ingredients according to claim 1, wherein It further includes a graphene foam thermal conductivity enhancement layer, which is composed of three-dimensional porous graphene foam, with a thickness of 0.1 - 0.3 mm, and is disposed between the thermal insulation layer and the reflection shielding layer.

3. The heating film for far-infrared heating and drying tobacco and tea ingredients based on graphene according to claim 1 or 2, characterized in that, The mass ratio of the graphene powder to the silver nanowires is 3:1, the thickness of the composite conductive layer is 0.03 mm, and the micropore diameter is 50 - 200 nm.

4. The heating film for far-infrared heating and drying tobacco and tea ingredients based on graphene according to claim 2, characterized in that, The porosity of the graphene foam thermal conductivity enhancement layer is 80 - 95%, and the pore diameter is 10 - 200 μm.

5. The heating film for far-infrared heating and drying of tobacco and tea ingredients based on graphene according to claim 1, wherein, The thickness of the flexible base layer is 0.2 mm, and the thickness of the thermal insulation layer is 0.15 mm.

6. The heating film for far-infrared heating and drying tobacco and tea ingredients based on graphene according to claim 1, characterized in that, The thickness of the reflection shielding layer is 0.07 mm, and the thickness of the protective coating is 0.02 mm.

7. The heating film for far-infrared heating and drying of tobacco and tea ingredients based on graphene according to claim 1, characterized in that, The mass ratio of the boron nitride nanosheets in the mixed material of the boron nitride nanosheets and polyethylene is 15% - 30%.

8. The heating film for far-infrared heating and drying of tobacco and tea ingredients based on graphene according to claim 7, characterized in that, The particle size of the boron nitride nanosheets is 100 - 500 nm.

9. A method for manufacturing a heating film based on any one of the heating films of claims 1 to 8, characterized in that, Including the following steps: S1. Pretreatment of the flexible base layer: Cut a polyimide film with a thickness of 0.1 - 0.3 mm into the required size, and place it in a vacuum plasma treatment device. Introduce a mixed gas of argon and oxygen, control the gas flow rate to be 20 - 30 sccm, the chamber pressure to be 10 - 50 Pa, turn on the radio frequency power supply, set the power to 200 - 300 W, and treat for 5 - 10 minutes to form a uniform microporous structure with a pore diameter of 50 - 200 nm on the surface of the flexible base layer; S2. Preparation of the composite conductive layer: Add graphene powder and silver nanowires at a mass ratio of 2 - 4:1 to an N-methylpyrrolidone solvent, control the solid content to be 5% - 8%, disperse with an ultrasonic cell disruptor for 30 - 45 minutes to obtain a homogeneous slurry, use a slot coater to coat the slurry on the surface of the flexible base layer, and pre-cure in a hot air circulation oven at 80 - 100 °C for 10 - 15 minutes to form a composite conductive layer with a thickness of 0.02 - 0.05 mm; S3. Coating of the thermal insulation layer: Mix boron nitride nanosheets and molten polyethylene at a mass ratio of 15% - 30%, stir at a temperature of 180 - 200 °C and a stirring rate of 300 - 500 rpm, with the particle size of the boron nitride nanosheets being 100 - 500 nm. Use an electrostatic spraying device to uniformly spray the mixed material on the surface of the composite conductive layer, and after cooling to room temperature, form a thermal insulation layer with a thickness of 0.1 - 0.2 mm; S4. Graphene foam layer composite: Cut the graphene foam sheet with a thickness of 0.1 - 0.3 mm into the required size, and then attach it to the surface of the thermal insulation layer through a hot pressing process; S5. Reflective shielding layer composite: Align and stack the aluminum foil and the PET film. The thickness of the aluminum foil is 0.02 - 0.05 mm, and the thickness of the PET film is 0.03 - 0.05 mm. Then place them in a hot press, set the temperature at 150 - 180 °C, the pressure at 5 - 8 MPa, and keep the pressure for 20 - 40 seconds to completely bond the two layers of materials. After cutting, attach it to the surface of the graphene foam layer, and the edge is processed by laser edge sealing; S6. The protective coating is cured. The fluorinated modified silicone resin is sprayed on the surface of the reflective shielding layer and placed in an ultraviolet curing machine with a wavelength of 365 nm and a light intensity of 50 - 80 mW / cm 2 , and cured for 20 - 30 seconds to form a protective coating with a thickness of 0.01 - 0.03 mm.

10. An air heat pump based on any one of the heating films of claims 1 to 8, characterized in that, Including: A box body, a blower fan, and a plurality of heating modules. An air inlet is provided at the right end of the box body, and an air outlet is provided at the left end. The blower fan is installed in the air inlet, and a plurality of heating modules are longitudinally and parallelly installed at intervals in the box body.

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