Graphene electric heating film for drying and disinfection equipment, preparation method and application thereof

Abstract

The invention discloses a method for preparing a graphene electric heating film for drying and disinfecting equipment, comprising the following steps: S1: forming an insulating-based-aluminum-graphene film layer by compounding an aluminum-based graphene heating layer on an insulating-based layer; S2: preparing a conductive-Cu-doped nickel sulfide conductive sheet; S3: laminating the conductive sheet prepared in step S2 to both ends of the composite aluminum-based graphene heating layer prepared in step 1; S4: preparing a composite nano-silver sulfide / silver-doped graphene sterilization layer; S5: compounding the composite nano-silver sulfide / silver-doped graphene sterilization layer with the composite aluminum-based graphene heating layer prepared in step S3 to obtain a finished graphene electric heating film; the invention can significantly improve the infrared heating performance, thermal efficiency and sterilization performance of the graphene heating film through reasonable design.

Description

Technical Field

[0001] The present invention belongs to the technical field of drying equipment, and in particular relates to a graphene electric heating film for drying and sterilizing equipment, a preparation method and an application thereof. Background Art

[0002] Graphene is a kind of carbon atom in sp 2 The hybrid orbital composition is a two-dimensional carbon nanomaterial with a hexagonal honeycomb lattice, which has excellent optical, electrical and mechanical properties. Since graphene is a good conductor of electricity and heat, it can be used in heating films to conduct electricity and generate heat when powered on. On the other hand, after the heating film generates heat, graphene can quickly transfer the heat, heating is faster and the temperature is more balanced. CN108559226B discloses a graphene heating film, which includes a film-forming component and a curing agent, and conductive fillers are added to the film-forming component and the curing agent. The conductive fillers include graphene, acetylene black and carbon nanotubes. Since the specific surface area of ​​graphene and carbon nanotubes is very large, they are easily agglomerated when directly mixed with resin, resulting in poor use of the graphene resin heating film. CN109362131 B discloses a heating film with a graphene-based hot-pressed copper sheet structure and a preparation method thereof, which forms a conductive electrode by fixing two electrode copper strips on a graphene layer by hot pressing, and realizes heating of the graphene layer after power is applied. However, the activity of a single copper-based electrode is not high, resulting in the electrothermal conversion efficiency being affected after it is combined with graphene. In addition, the existing graphene heating films mostly have a single heating function. When they are applied to drying and disinfection equipment, high-temperature disinfection is required. However, many products such as knitted clothing and underwear are not suitable for drying at high temperatures, and therefore cannot achieve the effect of thorough disinfection. Summary of the invention

[0003] The purpose of the present invention is to provide a graphene electric heating film for drying and sterilizing equipment, a preparation method and its application, so as to solve the problems raised in the above-mentioned background technology.

[0004] To solve this technical problem, the technical solution of the present invention is:

[0005] A method for preparing a graphene electric heating film for drying and disinfecting equipment comprises the following steps:

[0006] S1: Compounding an aluminum-based graphene heating layer on an insulating base layer to form an insulating base-aluminum-graphene film layer;

[0007] S2: Preparation of conductive sheet - Cu doped nickel sulfide conductive sheet;

[0008] S3: attaching the conductive sheet obtained in step S2 to both ends of the composite aluminum-based graphene heating layer obtained in step 1;

[0009] S4: Preparation of composite nano silver sulfide / silver-doped graphene bactericidal layer;

[0010] S5: Compounding the composite nano silver sulfide / silver-doped graphene sterilization layer with the composite aluminum-based graphene heating layer obtained in step S3 to obtain a finished graphene electric heating film.

[0011] Preferably, step S1 includes the following sub-steps:

[0012] S11: taking an insulating base layer, and depositing a molded aluminum layer on the insulating base layer by a vapor deposition method to form an insulating base-aluminum film;

[0013] S12: preparing a graphene suspension; adding graphene oxide and hydrazine to a reactor, ultrasonically dispersing, heating to a reaction temperature for reaction, and obtaining a graphene precipitate; washing the precipitate, adding water and a surfactant again, and ultrasonically dispersing to obtain a graphene suspension;

[0014] S13: The graphene suspension obtained in step S12 is atomized by an ultrasonic atomizer to form a precursor atomized liquid, and nitrogen is introduced into the precursor atomized liquid to form a stable airflow to spray toward the aluminum film side of the insulating base-aluminum film; a graphene liquid film is formed on the surface of the aluminum layer;

[0015] S14: Drying the insulating base-aluminum-graphene liquid film under vacuum conditions at 50-80° C. for 10-20 min to obtain an insulating base-aluminum-graphene film layer.

[0016] The invention reduces graphene oxide by hydrazine to obtain a graphene suspension, adds a surfactant to prevent graphene from agglomerating, and simultaneously atomizes the graphene suspension by an ultrasonic atomizer to form a graphene atomized liquid. During ultrasonic atomization, some fine agglomerated graphenes are further dispersed, and the graphene film formed by spraying after atomization can be formed in a directional manner, and the film formation is more uniform than that by suction filtration and DVC deposition.

[0017] Preferably, the insulating base layer is a high temperature resistant polyimide film.

[0018] Preferably, the ultrasonic frequency of the ultrasonic atomization device is 5 MHZ;

[0019] Preferably, the temperature of the graphene suspension is controlled at 70°C.

[0020] Preferably, step S2 includes the following sub-steps:

[0021] S21: pretreating the nickel foam;

[0022] S22: Weigh appropriate amounts of thiourea, copper nitrate and distilled water, add into Teflon liner, stir for 30 minutes, immerse the pretreated nickel foam in the mixed solution, carry out hydrothermal reaction, keep the reactor at 120°C for 12 hours, and after natural cooling, wash the reacted nickel foam with distilled water and alcohol in turn, and finally keep at 60°C in a vacuum drying oven for 8 hours to obtain a conductive Cu-doped nickel sulfide conductive sheet.

[0023] Preferably, the molar amount of copper nitrate is 15 mmoL.

[0024] The method for pretreating the nickel foam of the present invention is as follows: placing the cut strip nickel foam in dilute hydrochloric acid, ultrasonically treating for 20 minutes to remove the surface oxide layer, then ultrasonically treating in distilled water and anhydrous ethanol for 20 minutes each, and finally keeping warm at 60°C in a vacuum drying oven for 8 hours, drying and setting aside.

[0025] The present invention uses nickel foam as a nickel source, and while preparing nickel sulfide with excellent conductivity, copper is doped to obtain Cu-doped nickel sulfide. Compared with a single copper-based conductive sheet, the Cu-doped nickel sulfide has more active electron sites and less heat consumption.

[0026] Preferably, step S4 of preparing the composite nano silver sulfide / silver-doped graphene sterilization layer comprises the following steps:

[0027] S41: preparing a graphene suspension;

[0028] S42: dripping sodium hydroxide into a silver nitrate solution to obtain liquid silver hydroxide, adding the silver hydroxide dissolved in water to a graphene suspension under stirring conditions, and subjecting the mixture to ultrasonic vibration so that the silver hydroxide is embedded in the graphene through a metal bond to obtain a dispersion A;

[0029] S43: Preparation of nano silver sulfide:

[0030] Dissolve silver nitrate and sulfur powder in an organic solvent, add polyvinyl pyrrolidone (PVP), and react at 150-180°C for 4-6 hours; then cool, centrifuge, and wash to obtain spherical silver sulfide;

[0031] S45: adding the nano silver sulfide prepared in step S43 to N,N-dimethylformamide, and ultrasonically dispersing for 1-2 hours to obtain dispersion B;

[0032] S46: After mixing dispersion A and dispersion B, react at a temperature of 80-95° C. for 3-4 hours to obtain a nano-silver sulfide / silver-doped graphene suspension;

[0033] S47: atomizing the suspension obtained in step S46 through an ultrasonic atomizer to form a precursor atomized liquid, introducing nitrogen into the precursor atomized liquid to form a stable airflow for spraying on the insulating middle layer; forming a nano silver sulfide / silver-doped graphene liquid film on the surface of the insulating middle layer;

[0034] Preferably, the mixing ratio of dispersion A to dispersion B is 4:1.

[0035] Preferably, the nano silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer are compounded by a polyimide adhesive.

[0036] First, a polyimide adhesive is coated on the back of the nano-silver sulfide / silver-doped graphene film, and then it is composited on the aluminum-based graphene heating layer.

[0037] The present invention also aims to provide a graphene electric heating film for drying and sterilizing equipment;

[0038] In order to solve this technical problem, the technical solution of the present invention is: comprising an insulating base layer, an aluminum-based graphene heating layer is arranged on the insulating base layer, Cu-doped nickel sulfide conductive sheets are arranged on both ends of the aluminum-based graphene heating layer, and a composite nano-silver sulfide / silver-doped graphene sterilization layer is arranged above the aluminum-based graphene heating layer; an insulating middle layer is formed between the composite nano-silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer;

[0039] The present invention also aims to provide an application of a graphene heating film in a drying and disinfection device;

[0040] To solve this technical problem, the technical solution of the present invention is: the drying and disinfection equipment includes a barrel body, the barrel body includes an outer cylinder and an inner cylinder connected to each other, the graphene heating film prepared by the above method is bonded to the inner wall of the inner cylinder, a lifting and rotating pallet is provided at the bottom of the inner cylinder, the upper surface of the lifting and rotating pallet is bonded with the graphene heating film, the lifting and rotating pallet is connected to the lifting and rotating device, and also includes a microwave generator array, the microwave generator array is arranged on the lifting and rotating device, a drying buffer zone is formed between the top surface of the lifting and rotating pallet and the inner wall of the inner cylinder, a sterilization drying zone is formed between the bottom surface of the lifting and rotating pallet and the graphene heating film on the inner cylinder wall, and a pressure control detection valve is provided on the barrel body.

[0041] Preferably, the method for drying and disinfecting the drying and disinfecting equipment comprises the following steps:

[0042] Q1: Raise the lifting and rotating support plate to the top of the graphene heating film on the side wall of the inner cylinder, and divide the inner cylinder into a drying buffer zone and a sterilization and drying zone; turn on the power, rotate the lifting and rotating support plate while preheating, and turn on the microwave generator array for 5S-10S to stimulate the nano-silver sulfide / silver-doped graphene sterilization layer on the surface of the graphene heating film, further improving the ability of nano-silver sulfide to capture electrons;

[0043] Q2: Turn off the microwave generator array and continue to preheat the sterilization and drying area for 10-20 minutes; after the preheating is completed, put the objects to be dried into the inner drum and place them on the lifting and rotating tray;

[0044] Q3: The lifting and rotating tray is lowered and rotated to bring the object to be dried into the sterilization and drying area. While rotating, the object to be dried is brought into contact with the hot air and the graphene heating film on the cylinder wall through centrifugal force for sterilization and drying; and the hot air evaporated from the object rises and stays in the drying buffer area to continue to be heated;

[0045] Q4: The objects to be dried stay in the sterilization and drying area for 10-15 minutes, the lifting and rotating tray is raised, and the objects to be dried are placed in the drying buffer area. At the same time, the microwave generator array is turned on for 5S-10S;

[0046] Q5: Turn off the microwave generator array and keep the object to be dried in the drying buffer area for 10-13 minutes; the heated air in the drying buffer area is used for further drying, while the hot air cools and sinks into the sterilization drying area to continue to be heated;

[0047] Q6: Repeat steps Q3 to Q5 until drying is completed, and at the same time detect the air pressure in the cylinder. If it is greater than the preset pressure value, the pressure is released through the pressure control detection valve.

[0048] The present invention adopts a drying buffer zone and a sterilization drying zone cyclic drying method. On the one hand, it can make full use of the residual heat of the hot steam evaporated after drying to further dry the object. At the same time, when the sterilization drying zone is activated, the hot air is accumulated, which can instantly increase the contact area with the object to be dried, and the drying is faster. The rotation of the lifting and rotating support plate drives the air in the cylinder to perform centrifugal motion, so that the composite nano silver sulfide / silver-doped graphene sterilization layer can quickly combine with bacteria in the air to sterilize.

[0049] The above technical scheme has the beneficial effects of the present invention as follows: an aluminum-based graphene heating layer is arranged on the insulating base layer of the present invention, and the aluminum layer has a good infrared radiation effect. Combined with the graphene heating layer, the infrared heating performance of the heating film can be significantly improved, and the thermal utilization rate can be improved; the heating film made by replacing the single Cu conductive sheet with a Cu-doped nickel sulfide conductive sheet has a 50% decrease in the time required to reach 60°C, and the maximum surface temperature that can be achieved has been increased by 15%, making the heating efficiency higher; a composite nano-silver sulfide / silver-doped graphene bactericidal layer is added; the graphene is combined with nano-silver sulfide, and the bactericidal effect is more significant. At the same time, when used, the absorption of microwaves by nano-silver sulfide increases the ability of nano-silver sulfide to capture electrons, thereby significantly improving the bactericidal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of the drying and disinfecting equipment in the present invention; DETAILED DESCRIPTION

[0051] like Figure 1 As shown, in order to further explain the technical solution of the present invention, the present invention is described in detail through specific embodiments below.

[0052] Example 1

[0053] This embodiment discloses a graphene electric heating film for drying and disinfecting equipment, comprising an insulating base layer, an aluminum-based graphene heating layer is arranged on the insulating base layer, Cu-doped nickel sulfide conductive sheets are arranged on both ends of the aluminum-based graphene heating layer, and a composite nano-silver sulfide / silver-doped graphene sterilization layer is arranged above the aluminum-based graphene heating layer; an insulating middle layer is formed between the composite nano-silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer;

[0054] The method for preparing the graphene electric heating film comprises the following steps:

[0055] S1: Forming an insulating base-aluminum-graphene film layer; taking a polyimide film, cutting the size into 0.5m*0.5m; at a temperature of 1100℃, the aluminum wire is vaporized and deposited on the polyimide film to form an aluminum film for standby use; adding graphene oxide and hydrazine to a reactor, ultrasonically dispersing for 3h, heating to 90℃ and reacting for 3h to obtain a graphene precipitate; washing the precipitate, adding water and a surfactant again, and ultrasonically dispersing to obtain a graphene suspension, wherein the surfactant and graphite The mass ratio of the graphene precipitate is 1:20; the graphene suspension is further atomized by an ultrasonic atomizer to form a precursor atomized liquid, and the ultrasonic frequency of the ultrasonic atomization device is 4.5MHZ; the temperature of the graphene suspension is controlled at 60°C, nitrogen is introduced into the precursor atomized liquid to form a stable airflow and sprayed onto the aluminum film side of the insulating base-aluminum film to form a graphene liquid film on the surface of the aluminum layer; the insulating base-aluminum-graphene liquid film is dried at 50°C under vacuum conditions for 20 minutes to obtain an insulating base-aluminum-graphene film layer.

[0056] S2: Prepare a conductive sheet - Cu doped nickel sulfide conductive sheet; cut the nickel foam with a thickness of 0.2mm into a specification of 2.5cm*40cm, place it in dilute hydrochloric acid, ultrasonically treat it for 40min to remove the surface oxide layer, then ultrasonically treat it in distilled water and anhydrous ethanol for 30min each, and finally keep it in a vacuum drying oven at 60℃ for 8 hours, and set it aside after drying; weigh 15mmoL thiourea, copper nitrate and distilled water in appropriate amounts, wherein the molar amount of copper nitrate is 12mmoL, add Teflon liner, stir for 30 minutes, immerse the pretreated nickel foam in the mixed solution, and carry out hydrothermal reaction. The reactor is kept at 120℃ for 12 hours. After natural cooling, the reacted nickel foam is washed with distilled water and alcohol in turn, and finally kept in a vacuum drying oven at 60℃ for 8 hours to obtain a conductive Cu doped nickel sulfide conductive sheet;

[0057] S3: preparing a composite nano silver sulfide / silver-doped graphene sterilization layer; preparing a graphene suspension in the same manner as step S1, dropping sodium hydroxide into a silver nitrate solution to obtain liquid silver hydroxide, adding the silver hydroxide dissolved in water to the graphene suspension under stirring conditions, ultrasonically vibrating, and embedding the silver hydroxide into the graphene through metal bonds; obtaining a dispersion A for use; dissolving silver nitrate and sulfur powder in an organic solvent, adding polyvinyl pyrrolidone (PVP), and reacting at 150-180° C. for 4-6 hours; cooling, centrifuging, and washing to obtain a product, and then adding the nano silver sulfide to N,N- Dissolve in dimethylformamide, ultrasonically disperse for 1-2h, and then prepare dispersion B. Mix dispersion A and dispersion B and react at a temperature of 80-95°C for 3-4h; obtain a nano silver sulfide / silver-doped graphene suspension, wherein the mixing ratio of dispersion A to dispersion B is 4:1, then add a surfactant to the obtained suspension and atomize it through an ultrasonic atomizer to form a precursor atomized liquid, wherein the suspension temperature is maintained at 60°C, and nitrogen is introduced into the precursor atomized liquid to form a stable airflow and sprayed on the insulating middle layer; a nano silver sulfide / silver-doped graphene liquid film is formed on the surface of the insulating middle layer, and dried under vacuum conditions at 50°C for 20min;

[0058] S4: Lay the conductive sheet prepared in step S2 on both ends of the composite aluminum-based graphene heating layer prepared in step 1; then coat the back of the composite nano-silver sulfide / silver-doped graphene film with a polyimide adhesive, and then composite it on the aluminum-based graphene heating layer, and at the same time fix and laminate the aluminum-based graphene heating layer-conductive sheet-nano-silver sulfide / silver-doped graphene film.

[0059] Example 2

[0060] The difference from Example 1 is that: in step S1, the ultrasonic frequency of the ultrasonic atomization device is 5 MHZ;

[0061] Example 3

[0062] The difference from Example 1 is that: in step S1, the ultrasonic frequency of the ultrasonic atomization device is 5.5 MHZ;

[0063] Example 4

[0064] The difference from Example 1 is that: in step S1, the ultrasonic frequency of the ultrasonic atomization device is 6 MHZ;

[0065] Example 5

[0066] The difference from Example 2 is that: in step S1, the temperature of the graphene suspension is controlled at 65°C;

[0067] Example 6

[0068] The difference from Example 2 is that: in step S1, the temperature of the graphene suspension is controlled at 70°C;

[0069] Example 7

[0070] The difference from Example 2 is that: in step S1, the temperature of the graphene suspension is controlled at 75°C;

[0071] Example 8

[0072] The difference from Example 6 is that: in step S2, the molar amount of copper nitrate is 15mmoL;

[0073] Example 9

[0074] The difference from Example 6 is that: in step S2, the molar amount of copper nitrate is 15.5 mmoL;

[0075] Example 10

[0076] The difference from Example 6 is that: in step S2, the molar amount of copper nitrate is 17mmoL;

[0077] Embodiment 11

[0078] The difference from Example 8 is that in step S3, the mixing ratio of dispersion A and dispersion B is 3:1;

[0079] Example 12

[0080] The difference from Example 8 is that in step S3, the mixing ratio of dispersion A and dispersion B is 2:1;

[0081] Example 13

[0082] The difference from Example 8 is that in step S3, the mixing ratio of dispersion A to dispersion B is 0.5:1;

[0083] Comparative Example 1

[0084] A graphene electric heating film for drying and disinfecting equipment comprises an insulating base layer, on which an aluminum-based graphene heating layer is arranged, Cu conductive sheets are arranged on both ends of the aluminum-based graphene heating layer, and a composite nano-silver sulfide / silver-doped graphene sterilization layer is arranged above the aluminum-based graphene heating layer; an insulating middle layer is formed between the composite nano-silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer; wherein the aluminum-based graphene heating layer and the composite nano-silver sulfide / silver-doped graphene sterilization layer are prepared by the method in Example 1.

[0085] Comparative Example 2

[0086] A graphene electric heating film for drying and disinfecting equipment comprises an insulating base layer, a graphene heating layer is arranged on the insulating base layer, Cu-doped nickel sulfide conductive sheets are arranged on both ends of the graphene heating layer, a composite nano silver sulfide / silver-doped graphene sterilization layer is arranged above the graphene heating layer; an insulating middle layer is formed between the composite nano silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer; wherein the preparation method of the graphene heating layer is as follows: adding graphene oxide and hydrazine to a reactor, ultrasonically dispersing for 3 hours, heating to 90°C for reaction for 3 hours, and obtaining a graphene precipitate; washing the precipitate, adding water and a surfactant again, and ultrasonically dispersing for 3 hours; The graphene suspension is dispersed to obtain a graphene suspension, wherein the mass ratio of the surfactant to the graphene precipitate is 1:20; the graphene suspension is further atomized by an ultrasonic atomizer to form a precursor atomized liquid, and the ultrasonic frequency of the ultrasonic atomizer is 4.5 MHZ; the temperature of the graphene suspension is controlled at 60° C., nitrogen is introduced into the precursor atomized liquid to form a stable airflow for spraying the insulating base, and a graphene liquid film is formed on the surface of the insulating base; the insulating base-graphene liquid film is dried at 50° C. under vacuum conditions for 20 min to obtain an insulating base-graphene film layer; the Cu-doped nickel sulfide conductive sheet and the nano-silver sulfide / silver-doped graphene sterilization layer are prepared by the method in Example 1.

[0087] Comparative Example 3

[0088] A graphene electric heating film for drying and sterilizing equipment comprises an insulating base layer, on which an aluminum-based graphene heating layer is arranged, on both ends of the aluminum-based graphene heating layer are arranged Cu-doped nickel sulfide conductive sheets, an insulating layer is composited above the Cu-doped nickel sulfide conductive sheet, and the aluminum-based graphene heating layer and the Cu-doped nickel sulfide conductive sheet are prepared by the method in Example 1.

[0089] Experimental results:

[0090] 1. Measure the heating efficiency of Examples 1 to 10;

[0091] Test method: Connect the heating film to the power supply, set the working voltage to 4V, and measure the maximum temperature reached on the surface of each heating film, the time required to reach 60℃, and the far-infrared performance;

[0092] Table 1 Thermal performance data of Examples 1-10 and Comparative Examples 1-2

[0093]

[0094] It can be seen from Table 1 that, by comparing Example 1 and Comparative Example 1, the time required for the heating film to reach 60°C is reduced by 50% and the maximum surface temperature that can be achieved is increased by 15%. This is mainly because the Cu-doped nickel sulfide conductive sheet has high electronic site activity, low resistance, and generates a large current.

[0095] Comparing Examples 1-4, it can be seen that as the ultrasonic frequency of the ultrasonic atomization device increases, the time required to reach 60°C gradually decreases, and the higher the maximum surface temperature that can be achieved, it is proved that the higher the ultrasonic frequency of the ultrasonic atomization device, the more uniform the dispersion of the suspension, and the better the conductivity of the obtained graphene insulating base-aluminum-graphene film layer. However, when the ultrasonic frequency of the ultrasonic atomization device is further increased, the time required to reach 60°C and the maximum surface temperature that can be achieved, the change trend becomes gentle; therefore, the optimal ultrasonic frequency of the ultrasonic atomization device is 5MHZ;

[0096] By comparing Example 2 and Examples 5-7, it can be seen that as the temperature of the graphene suspension increases, the time required to reach 60°C gradually decreases and then tends to be stable, and the highest surface temperature that can be achieved becomes higher and then tends to be stable, proving that the optimal graphene suspension temperature is 70 degrees Celsius, and further increase in temperature has little effect on the dispersion performance of the graphene suspension;

[0097] By comparing Example 6 with Examples 8-10, it can be seen that as the molar amount of copper nitrate increases, the time required to reach 60°C first decreases and then increases, and the maximum surface temperature that can be achieved first increases and then decreases. This is because as the molar amount of copper nitrate increases, the external morphology of the conductive Cu-doped nickel sulfide conductive sheet changes, affecting its conductivity, which proves that the optimal molar amount of copper nitrate added is 15mmoL.

[0098] 2. Measure the radiation performance of Example 1 and Comparative Example 2;

[0099] An infrared wavelength detector is used to detect the infrared wavelength radiation state of the heating film when the temperature rises from room temperature to the highest surface temperature;

[0100] Table 2 Comparison of infrared radiation between Example 1 and Comparative Example 2

[0101] Group Can it radiate infrared wavelength stably? Example 1 Continuous radiation of infrared wavelength of 8-14um Comparative Example 2 Intermittent radiation of 8-14um infrared wavelength

[0102] It can be seen from Table 2 that, by comparing Example 1 with Comparative Example 2, the aluminum film can effectively increase the infrared emission performance of the heating film and can effectively radiate heat into space in the form of far infrared.

[0103] 3. Comparison of bactericidal performance:

[0104] Test method:

[0105] Take the heating films of Example 1 and Comparative Example 3, denoted as heating film 1 and heating film 2, respectively, drip Staphylococcus aureus on the surfaces thereof, respectively count the total number of colonies on the heating films 1 and 2 by using a colony counter, respectively, heat for 2 min, 4 min, 6 min, 8 min, and 10 min, respectively, and calculate the number of bacteria killed on the heating films 1 and 2; sterilization rate = {(initial bacterial count - surviving bacterial count) / initial bacterial count} * 100%;

[0106] Table 3 Comparison of bactericidal performance of Example 1 and Comparative Example 3

[0107]

[0108] It can be seen from Table 3 that the heating film prepared in Example 1 has the function of sterilization at low temperature, while the heating film prepared in Comparative Example 3 can only be sterilized under high temperature conditions, and the sterilization performance of the heating film prepared in Example 1 increases linearly.

[0109] The same method as above was used to test the bactericidal performance of the heating films prepared in Example 1 and Examples 11-13;

[0110] Table 4 Comparison of bactericidal performance of Example 1, Examples 11-13

[0111]

[0112]

[0113] As can be seen from Table 4, by comparing Example 1 and Examples 11-13, it can be seen that as the mixing ratio of dispersion A and dispersion B decreases, the bactericidal performance gradually weakens. The main reason is that graphene has a larger specific surface area and can adsorb more bacteria. In combination with silver sulfide, a significant bactericidal effect is achieved, proving that the optimal mixing ratio of dispersion A and dispersion B is 4:1.

[0114] Take two identical graphene heating films prepared in Example 1 and place them in a sealed container, wherein a microwave transmitting device is set in one of the sealed containers, and the microwave frequency is 2463 MHz.

[0115] Table 5 Effect of microwave on the bactericidal performance of graphene heating film in Example 1

[0116]

[0117] It can be seen from Table 5 that the sterilization efficiency of the graphene heating film with added microwave irradiation is significantly higher than that of the graphene heating film without irradiation, and can reach a sterilization balance more quickly.

[0118] Embodiment 14

[0119] In this embodiment, the graphene heating film is applied to the drying and disinfection equipment;

[0120] The drying and disinfection equipment includes a barrel body, which includes an outer barrel 100 and an inner barrel 101 connected to each other. The graphene heating film 102 made by the above method is bonded to the inner wall of the inner barrel. A lifting and rotating pallet 103 is provided at the bottom of the inner barrel. The upper surface of the lifting and rotating pallet is bonded with the graphene heating film. The lifting and rotating pallet is connected to the lifting and rotating device, and also includes a microwave generator array 104. The microwave generator array is arranged on the lifting and rotating device. A drying buffer zone 105 is formed between the top surface of the lifting and rotating pallet and the inner wall of the inner barrel, and a sterilization drying zone 106 is formed between the bottom surface of the lifting and rotating pallet and the inner barrel wall graphene heating film. A pressure control detection valve 107 is provided on the barrel body. Among them, the lifting and rotating device is a commercially available component, including a motor and a cylinder, the output shaft of the motor is connected to the cylinder body of the cylinder, and the piston rod of the cylinder is connected to the lifting and rotating support plate; the microwave generator array 104 is also a commercially available component, and a concave groove is opened on the piston rod of the cylinder, and the microwave generator array 104 is placed in the concave groove, and the upper and lower heights of the microwave generator array are the same as the height of the graphene heating film attached to the inner wall of the inner cylinder.

[0121] Among them, the method for drying and disinfecting the drying and disinfecting equipment comprises the following steps:

[0122] Q1: Raise the lifting and rotating support plate to the top of the graphene heating film on the side wall of the inner cylinder, and divide the inner cylinder into a drying buffer zone and a sterilization and drying zone; turn on the power, rotate the lifting and rotating support plate while preheating, and turn on the microwave generator array for 5S-10S to stimulate the nano-silver sulfide / silver-doped graphene sterilization layer on the surface of the graphene heating film, further improving the ability of nano-silver sulfide to capture electrons;

[0123] Q2: Turn off the microwave generator array and continue to preheat the sterilization and drying area for 10-20 minutes; after the preheating is completed, put the objects to be dried into the inner drum and place them on the lifting and rotating tray;

[0124] Q3: The lifting and rotating tray is lowered and rotated to bring the object to be dried into the sterilization and drying area. While rotating, the object to be dried is brought into contact with the hot air and the graphene heating film on the cylinder wall through centrifugal force for sterilization and drying; and the hot air evaporated from the object rises and stays in the drying buffer area to continue to be heated;

[0125] Q4: The objects to be dried stay in the sterilization and drying area for 10-15 minutes, the lifting and rotating tray is raised, and the objects to be dried are placed in the drying buffer area. At the same time, the microwave generator array is turned on for 5S-10S;

[0126] Q5: Turn off the microwave generator array and keep the object to be dried in the drying buffer area for 10-13 minutes; the heated air in the drying buffer area is used for further drying, while the hot air cools and sinks into the sterilization drying area to continue to be heated;

[0127] Q6: Repeat steps Q3 to Q5 until drying is completed, and at the same time detect the air pressure in the cylinder. If it is greater than the preset pressure value, the pressure is released through the pressure control detection valve.

[0128] The present invention adopts a drying buffer zone and a sterilization drying zone cyclic drying method. On the one hand, it can make full use of the residual heat of the hot steam evaporated after drying to further dry the object. At the same time, when the sterilization drying zone is activated, the hot air is accumulated, which can instantly increase the contact area with the object to be dried, and the drying is faster. The rotation of the lifting and rotating support plate drives the air in the cylinder to perform centrifugal motion, so that the composite nano silver sulfide / silver-doped graphene sterilization layer can quickly combine with bacteria in the air to sterilize.

Claims

1. A method for preparing a graphene electric heating film for drying and disinfecting equipment, characterized in that: The steps include: S1: Compounding an aluminum-based graphene heating layer on an insulating base layer to form an insulating base-aluminum-graphene film layer; S2: Preparation of conductive sheet - Cu doped nickel sulfide conductive sheet; S3: attaching the conductive sheet obtained in step S2 to both ends of the composite aluminum-based graphene heating layer obtained in step 1; S4: Preparation of composite nano silver sulfide / silver-doped graphene bactericidal layer; S5: Compounding the composite nano silver sulfide / silver-doped graphene sterilization layer with the composite aluminum-based graphene heating layer obtained in step S3 to obtain a finished graphene electric heating film; Wherein, step S4 prepares the composite nano silver sulfide / silver-doped graphene sterilization layer, comprising the following steps: S41: preparing a graphene suspension; S42: dripping sodium hydroxide into a silver nitrate solution to obtain liquid silver hydroxide, adding the silver hydroxide dissolved in water to a graphene suspension under stirring conditions, and subjecting the mixture to ultrasonic vibration so that the silver hydroxide is embedded in the graphene through a metal bond to obtain a dispersion A; S43: Preparation of nano silver sulfide: Dissolve silver nitrate and sulfur powder in an organic solvent, add polyvinyl pyrrolidone (PVP), and react at 150-180°C for 4-6 hours; then cool, centrifuge, and wash to obtain spherical silver sulfide; S45: adding the nano silver sulfide prepared in step S43 to N,N-dimethylformamide, and ultrasonically dispersing for 1-2 hours to obtain dispersion B; S46: After mixing dispersion A and dispersion B, react at a temperature of 80-95° C. for 3-4 hours to obtain a nano-silver sulfide / silver-doped graphene suspension; S47: The suspension obtained in step S46 is atomized by an ultrasonic atomizer to form a precursor atomized liquid, nitrogen is introduced into the precursor atomized liquid to form a stable airflow for spraying on the insulating middle layer; a nano silver sulfide / silver-doped graphene liquid film is formed on the surface of the insulating middle layer.

2. The method for preparing a graphene electric heating film for drying and sterilizing equipment according to claim 1, characterized in that: Step S1 includes the following sub-steps: S11: taking an insulating base layer, and depositing a molded aluminum layer on the insulating base layer by a vapor deposition method to form an insulating base-aluminum film; S12: preparing a graphene suspension; adding graphene oxide and hydrazine to a reactor, dispersing them by ultrasonic wave, heating them to a reaction temperature to react, and obtaining a graphene precipitate; washing the precipitate, adding water and a surfactant again, and dispersing them by ultrasonic wave to obtain a graphene suspension; S13: The graphene suspension obtained in step S12 is atomized by an ultrasonic atomizer to form a precursor atomized liquid, and nitrogen is introduced into the precursor atomized liquid to form a stable airflow to spray toward the aluminum film side of the insulating base-aluminum film; a graphene liquid film is formed on the surface of the aluminum layer; S14: Drying the insulating base-aluminum-graphene liquid film under vacuum conditions at 50-80° C. for 10-20 min to obtain an insulating base-aluminum-graphene film layer.

3. The method for preparing a graphene electric heating film for drying and sterilizing equipment according to claim 2, characterized in that: The ultrasonic frequency of the ultrasonic atomization device is 5MHZ.

4. The method for preparing a graphene electric heating film for drying and sterilizing equipment according to claim 2, characterized in that: The temperature of the graphene suspension was controlled at 70 °C.

5. The method for preparing a graphene electric heating film for drying and sterilizing equipment according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21: pretreating the nickel foam; S22: Weigh appropriate amounts of thiourea, copper nitrate and distilled water, add into Teflon liner, stir for 30 minutes, immerse the pretreated nickel foam in the mixed solution, carry out hydrothermal reaction, keep the reactor at 120°C for 12 hours, and after natural cooling, wash the reacted nickel foam with distilled water and alcohol in turn, and finally keep at 60°C in a vacuum drying oven for 8 hours to obtain a conductive Cu-doped nickel sulfide conductive sheet.

6. The method for preparing the graphene electric heating film for drying and sterilizing equipment according to claim 5, characterized in that: The molar amount of copper nitrate is 15mmoL.

7. The method for preparing a graphene electric heating film for drying and sterilizing equipment according to claim 1, characterized in that: The mixing ratio of dispersion A to dispersion B is 4:

1.

8. A graphene electric heating film for drying and sterilizing equipment, characterized in that: It is prepared using the preparation method described in any one of claims 1 to 7, and comprises an insulating base layer, an aluminum-based graphene heating layer is arranged on the insulating base layer, Cu-doped nickel sulfide conductive sheets are arranged on both ends of the aluminum-based graphene heating layer, and a composite nano-silver sulfide / silver-doped graphene sterilization layer is arranged above the aluminum-based graphene heating layer; an insulating middle layer is formed between the composite nano-silver sulfide / silver-doped graphene sterilization layer and the aluminum-based graphene heating layer.

9. The graphene electric heating film according to claim 8 is applied to a drying and disinfection device, characterized in that: The drying and disinfection equipment comprises a barrel body, which comprises an outer barrel and an inner barrel connected to each other, the graphene heating film prepared by the above method is laminated on the inner wall of the inner barrel, a lifting and rotating support plate is arranged at the bottom of the inner barrel, the upper surface of the lifting and rotating support plate is laminated with the graphene heating film, the lifting and rotating support plate is connected to the lifting and rotating device, and also comprises a microwave generator array, the microwave generator array is arranged on the lifting and rotating device, a drying buffer zone is formed between the top surface of the lifting and rotating support plate and the inner wall of the inner barrel, a sterilization and drying zone is formed between the bottom surface of the lifting and rotating support plate and the inner barrel wall graphene heating film, a pressure control detection valve is arranged on the barrel body, wherein the drying and disinfection method of the drying and disinfection equipment comprises the following steps: Q1: Raise the lifting and rotating support plate to the top of the graphene heating film on the side wall of the inner cylinder, and divide the inner cylinder into a drying buffer zone and a sterilization and drying zone; turn on the power, rotate the lifting and rotating support plate while preheating, and turn on the microwave generator array for 5S-10S to stimulate the nano-silver sulfide / silver-doped graphene sterilization layer on the surface of the graphene heating film, further improving the ability of nano-silver sulfide to capture electrons; Q2: Turn off the microwave generator array and continue to preheat the sterilization and drying area for 10-20 minutes; after the preheating is completed, put the objects to be dried into the inner drum and place them on the lifting and rotating tray; Q3: The lifting and rotating tray is lowered and rotated to bring the object to be dried into the sterilization and drying area. While rotating, the object to be dried is brought into contact with the hot air and the graphene heating film on the cylinder wall through centrifugal force for sterilization and drying; and the hot air evaporated from the object rises and stays in the drying buffer area to continue to be heated; Q4: The objects to be dried stay in the sterilization and drying area for 10-15 minutes, the lifting and rotating tray is raised, and the objects to be dried are placed in the drying buffer area. At the same time, the microwave generator array is turned on for 5S-10S; Q5: Turn off the microwave generator array and keep the object to be dried in the drying buffer area for 10-13 minutes; the heated air in the drying buffer area is used for further drying, while the hot air cools and sinks into the sterilization drying area to continue to be heated; Q6: Repeat steps Q3 to Q5 until drying is completed, and at the same time detect the air pressure in the cylinder. If it is greater than the preset pressure value, the pressure is released through the pressure control detection valve.

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