A preparation method of an environmentally friendly graphene heating film and its products and applications

Abstract

The present invention belongs to the technical field of heating films, and specifically relates to a method for preparing an environmentally friendly graphene heating film, as well as corresponding film materials and wearable devices. It is used to prepare a graphene heating film comprising a base layer, a graphene heating layer, a conductive layer, an electrode current-carrying strip, a heat storage slow-release layer and a protective layer, wherein the base material is made of recycled degradable cellulose and the protective layer is made of chitosan or other similar materials. The graphene heating layer and the conductive layer are patterned on the base layer by a gravure printing process, and the electrode current-carrying strip, the heat storage slow-release layer and the protective layer are composited with other materials by a hot pressing process. The graphene heating film prepared by the present invention has better degradability and is more environmentally friendly; the product has stronger flexibility and durability, and its texture is close to that of fabric, which can improve user experience. The preparation process has low raw materials and is suitable for assembly line production, which helps to reduce costs and has more commercial value.

Description

Technical Field

[0001] The present invention belongs to the technical field of heating films, and specifically relates to a method for preparing an environmentally friendly graphene heating film, corresponding film materials, and wearable devices. Background Art

[0002] Graphene is a two-dimensional nanomaterial composed of carbon atoms forming a hexagonal honeycomb lattice structure through sp2 hybrid orbitals and only one carbon atom thick. Graphene's unique structure gives it many excellent properties, such as a high theoretical specific surface area (2630m2 / g), ultra-high electron mobility (~200,000cm2 / vs), high thermal conductivity (5000W / mK), high Young's modulus (1.0TPa), and high transmittance (around 97.7%). Due to its structural and performance advantages, graphene has great application prospects in energy storage and conversion devices, nanoelectronic devices, multifunctional sensors, flexible wearable electronics, electromagnetic shielding, and corrosion protection. Given the flexibility and conductivity of graphene, a conductive ink is prepared by adding graphene slurry to ink. The ink is then sprayed and dried to form a flexible graphene heating layer, making it a graphene heating element. This has the characteristics of a fast production process, low material consumption, and low cost.

[0003] With the pursuit of environmental protection, it is imperative to improve the materials used to make traditional heaters, find more economical and environmentally friendly alternatives, and develop new green heating systems. Currently, the substrate materials commonly used in the preparation of graphene heating films are mostly non-degradable polymers, such as PET, PI, and acrylic, and the protective layers are often thinner versions of the same materials. These polymeric substrates and protective layers not only fail to meet environmentally friendly development requirements but also, to a certain extent, limit the flexibility, flex resistance, and service life of the heating films, restricting their practical applications. Therefore, improving the preparation process of graphene heating films to ensure environmental friendliness, good flexibility, and long-term stability is crucial for expanding their functionality and adaptability. Summary of the Invention

[0004] In order to solve the problems of existing graphene heating films such as non-degradability, insufficient flexibility and bending resistance, and poor long-term stability, the present invention provides a preparation method of an environmentally friendly graphene heating film, its products and applications.

[0005] The technical solutions provided by the present invention are as follows:

[0006] A method for preparing an environmentally friendly graphene heating film comprises the following steps:

[0007] S1: chitosan powder is mixed with a thickener, a cross-linking agent, and a plasticizer in proportion and dissolved in a solvent to obtain a chitosan solution; the chitosan solution is evenly coated on a mold and cured to obtain a chitosan film.

[0008] S2: Prepare graphene ink, use fabric made of recycled biodegradable fibers as the base material, print the conductive ink onto the base material through gravure printing, then heat and dry it at a constant temperature of 130°C, and cool it down on a wheel to form a patterned heating layer on the base material.

[0009] S3: Prepare silver paste material and print the silver paste onto the base material through gravure printing process, then heat and dry it at a constant temperature of 160°C, and then return it to the wheel for cooling, thereby forming a patterned conductive layer on the base material.

[0010] S4: Prepare the electrode current-carrying strip cut into a specified shape, place the electrode current-carrying strip at a specified position on the base material, and bond and solidify the electrode current-carrying strip to the base material through a hot pressing process. The electrode current-carrying strip forms an electrical connection with the heating layer through the conductive layer.

[0011] S5: Prepare nanofibers and / or fiber composite materials as heat storage slow-release materials, and evenly stack them on the surface of a base material comprising a heating layer, a conductive layer, and electrode current-carrying strips; then combine and solidify the heat storage slow-release material with the base material through a hot pressing process to form a heat storage slow-release layer.

[0012] S6: placing chitosan films on both sides of the base material forming the heat storage slow-release layer or on one side close to the heat storage slow-release layer, and then combining the chitosan film and the base material having the heat storage slow-release layer through a hot pressing process and curing to form a protective layer.

[0013] The obtained composite film material with a protective layer is an environmentally friendly graphene heating film. Depending on the number of layers of the chitosan film, the prepared products are divided into two types: single-sided coating and double-sided coating.

[0014] As a further improvement of the present invention, in step S1, the solvent is acetic acid or ethanol.

[0015] and / or

[0016] The chitosan solution is cured by heating or chemical cross-linking.

[0017] As a further improvement of the present invention, in step S2, the preparation method of graphene ink is as follows: graphene powder, nanographite, conductive carbon black, conductive resin and dispersant are fully mixed in a specified ratio to obtain graphene ink.

[0018] As a further improvement of the present invention, in step S2, the regenerated degradable fiber used as the base material includes triacetate fiber, viscose fiber, Tencel fiber or cupro fiber.

[0019] Wherein, the preparation method of viscose fiber type substrate is as follows:

[0020] The cellulose raw material is soaked in an alkaline solution to remove impurities and non-cellulose components.

[0021] The cellulose raw material treated with alkali is soaked in viscose solution to form viscose fiber.

[0022] The viscose fibers are soaked in a solvent to remove excess viscose and solvent before being filtered and washed.

[0023] The washed fiber material is formed into fibers by spinning or spraying, and then stretched and shaped by rotating centrifugal force or air flow.

[0024] Finally, the shaped fibers are subjected to heat treatment or chemical cross-linking, and the regenerated degradable fibers after curing are spun to produce the desired fabric.

[0025] As a further improvement of the present invention, the cellulose raw material is cotton, hemp, bamboo, straw, bark or other natural fiber materials.

[0026] and / or

[0027] The alkaline solution is sodium hydroxide solution.

[0028] and / or

[0029] The solvent for soaking the viscose fiber is a ketone or aldehyde solvent.

[0030] As a further improvement of the present invention, in steps S2 and S3, the graphene ink and silver paste are printed onto the base material by a roll-to-roll printing press; during the printing process, the graphene ink or silver paste is filled into the grooves in the gravure printing roller, and during the printing process, the material in the grooves contacts the base material and is then transferred to the base material.

[0031] As a further improvement of the present invention, in step S5, the electrode current-carrying bar adopts a nickel-plated copper electrode.

[0032] and / or

[0033] In steps S1 and S6, the chitosan powder used to prepare the protective film is replaced by chitosan derivatives, chitosan analogs and other polysaccharide materials.

[0034] The present invention also includes an environmentally friendly graphene heating film, which is prepared by the preparation method of the environmentally friendly graphene heating film as described above, and includes: a base layer prepared from recycled degradable fibers; an electrode current-carrying strip and a patterned graphene heating layer and a conductive layer located on the base layer; a heat storage slow-release layer covering the electrode current-carrying strip, the heating layer and the conductive layer; and a chitosan protective layer covering only the heat storage slow-release layer or simultaneously covering the heat storage slow-release layer and the base layer.

[0035] The present invention also includes an application of an environmentally friendly graphene heating film, in which a single-sided film-coated product prepared by the aforementioned preparation method of the environmentally friendly graphene heating film is used as a fabric for preparing self-heating clothing or accessories; or a double-sided film-coated product is used as an interlayer material in a self-heating wearable device.

[0036] The present invention also includes a self-heating wearable device, which includes the aforementioned environmentally friendly graphene heating film and a power supply module electrically connected to the electrode current-carrying strips in the environmentally friendly graphene heating film.

[0037] The technical solution provided by the present invention has the following beneficial effects:

[0038] The environmentally friendly flexible graphene heating film provided by this invention uses inexpensive and readily available raw materials, reducing production costs. The product's production process utilizes a roll-to-roll gravure printing process, flow drying, cooling, and hot pressing integrated production line, enabling large-scale commercial production.

[0039] Among them, the flexible graphene heating film uses green and environmentally friendly recycled degradable cellulose as the base and chitosan film as the protective layer. The product is easier to degrade, making it environmentally friendly and antibacterial.

[0040] The environmentally friendly flexible graphene heating film provided by the present invention has greatly improved the flexibility and durability of the graphene heating film after the material is improved, and has a texture similar to fabric. It can be widely used in various functional clothing, accessories and wearable devices, and can improve user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart of the steps of the method for preparing the environmentally friendly graphene heating film provided in Example 1 of the present invention.

[0042] Figure 2 This is a schematic structural diagram of the single-sided coated graphene heating film provided in Example 2 of the present invention.

[0043] Figure 3 This is a schematic structural diagram of the double-sided coated graphene heating film provided in Example 2 of the present invention.

[0044] The following are marked in the figure:

[0045] 1. Protective layer; 2. Heat storage and slow-release layer; 3. Electrode current-carrying strip; 4. Conductive layer; 5. Heating layer; 6. Base layer. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] Example 1

[0048] This embodiment provides a method for preparing an environmentally friendly graphene heating film, which is used to prepare a graphene heating film comprising a base layer, a graphene heating layer, a conductive layer, an electrode current carrying strip, a heat storage and slow-release layer, and a protective layer, wherein the base material is made of recycled degradable cellulose and the protective layer is made of chitosan or other similar materials. Specifically, Figure 1 As shown, the preparation method mentioned in this embodiment includes the following steps:

[0049] S1: chitosan powder is mixed with a thickener, a cross-linking agent, and a plasticizer in proportion and dissolved in a solvent to obtain a chitosan solution; the chitosan solution is evenly coated on a mold and cured to obtain a chitosan film.

[0050] The chitosan film in this embodiment is used to make a protective layer on the surface of the graphene heating film. The protective layer can play a role of wear resistance and skin-friendly, and has a certain waterproof performance. Based on the same requirements, in other embodiments, the chitosan film can also use chitosan derivatives (such as: N-acetyl chitosan (N-acetyl chitosan) and chitosan acid (such as: chitosansulfate, etc.), chitosan analogs (such as: chitosanase and chitosanase-like substances, etc.), other polysaccharide materials (for example, alginate, galactomannan and xylan, etc.).

[0051] In preparing the chitosan film, the present embodiment dissolves chitosan powder in a suitable solvent, such as acetic acid, ethanol, etc., to form a chitosan solution. The concentration of the solution can be adjusted as needed. In addition, the chitosan solution is mixed with other additives, such as thickeners, cross-linking agents, plasticizers, etc., to improve the performance and processing properties of the film.

[0052] The mixture is then stirred evenly using a stirrer to ensure that the components in the solution are evenly dispersed. The mixed solution is poured into a flat or round mold, and then the solution is evenly coated on the surface of the mold using a scraper or scraper or by shaking. At this point, the thickness of the coated solution can be adjusted according to the required film thickness. Place the coated chitosan solution in a well-ventilated environment and allow it to dry naturally. An oven or other drying equipment can also be used to accelerate the drying process. After ensuring that the film is completely dry, remove the film. During the preparation process of the chitosan film, the chitosan film needs to be cured and cross-linked to improve its mechanical properties and stability. Common curing methods include heat treatment, chemical cross-linking, etc.

[0053] S2: Prepare graphene ink, use fabric made of recycled biodegradable fibers as the base material, print the graphene ink onto the base material through gravure printing, then heat and dry it at a constant temperature of 130°C, and cool it back on the wheel to form a patterned heating layer on the base material.

[0054] In this embodiment, the graphene ink is prepared by thoroughly mixing graphene powder, nanographite, conductive carbon black, and a conductive resin with a dispersant in a specified ratio to obtain the graphene ink. In practical applications, by adjusting the ratio of the components, the graphene ink required for a graphene heating film that meets specific power requirements can be prepared.

[0055] In the solution of this embodiment, the base material is a fabric and is made of recycled biodegradable fibers. The recycled biodegradable fibers used in the base material include triacetate fiber, viscose fiber, Tencel fiber or cupro fiber, etc. Taking viscose fiber as an example, the preparation method of the base material in this embodiment is as follows:

[0056] First, cellulose raw materials such as cotton, hemp, bamboo, trees, shrubs, straw, and bark are soaked in an alkaline solution to remove impurities and non-cellulose components. The alkaline solution can be a sodium hydroxide solution.

[0057] The alkali-treated cellulose raw material is then immersed in a viscose solution. The viscose solution is typically composed of an adhesive and a solvent. In this embodiment, the viscose solution is a textile adhesive solution or a viscose cellulose solution. Upon contact with the viscose solution, the cellulose raw material absorbs the adhesive, thereby producing a viscose-coated cellulose raw material.

[0058] Next, the viscose-treated cellulose material is soaked in a solvent, such as an alcohol or ketone solvent, to remove excess viscose and solvent. The solvent-treated cellulose material is then filtered and washed to remove residual solvent and impurities.

[0059] Finally, the washed cellulose raw material is formed into fibers through spinning or air jetting. The fibers can be stretched and shaped using centrifugal force or airflow. The resulting fibers undergo a curing process, such as heat treatment or chemical crosslinking, to enhance their mechanical properties and stability. The cured fibers are then woven into a fabric, which becomes the desired base material.

[0060] This embodiment uses a printing process to prepare the required heating layer, which not only greatly improves production efficiency, but also allows complex patterning of the heating layer on the base material as needed to meet diverse market demands and support users to customize the heating layer pattern. Specifically, the heating layer preparation process in this embodiment is detailed as follows:

[0061] Prepare the substrate material made of recycled biodegradable cellulose and graphene ink to be printed. Make sure the surface of the substrate material is clean and flat, and remove any obvious dust or impurities. Use the gravure production process to etch the pattern or text to be printed on the gravure printing roller. The gravure printing roller can be made of metal or polymer material, and the surface of the printing roller has grooves with a specific pattern. Apply the graphene ink on the gravure. During the coating process, tools such as scrapers or rollers can be used to ensure that the ink evenly fills all the grooves in the printing roller. Next, pass the substrate material through the printing unit in the roll-to-roll printing machine. In the printing unit, the graphene ink in the gravure contacts the surface of the substrate material, and the ink is transferred from the grooves to the substrate material. Finally, after drying and curing, the patterned ink can be firmly attached to the surface of the substrate material.

[0062] In this embodiment, the graphene ink is heated and dried at a constant temperature of 130°C, followed by a recirculation cooling system. Recirculation cooling utilizes the heat transfer properties of a thermal medium. This system circulates the thermal medium through the equipment or system requiring cooling, then returns the cooled thermal medium to the cooling device, achieving both heat transfer and cooling.

[0063] S3: Prepare silver paste material and print the silver paste onto the base material through gravure printing process, then heat and dry it at a constant temperature of 160°C, and then return it to the wheel for cooling, thereby forming a patterned conductive layer on the base material.

[0064] Silver paste material is a viscous paste composed of a mechanical mixture of high-purity metallic silver particles, adhesives, solvents, and additives; this embodiment uses silver paste material to prepare a conductive layer located between the electrode current-carrying bar and the heating layer, thereby achieving stable electrical connection between the electrode current-carrying bar and the patterned conductive layer.

[0065] The conductive layer in this embodiment is prepared using the same printing process as the heating layer. Therefore, the printing process of the conductive layer is not described in detail in this embodiment. During the curing process of the conductive layer, the curing temperature of the silver paste material and the graphene ink is different. The curing temperature of the silver paste material is higher than that of the graphene ink, which is about 160°C.

[0066] S4: Prepare the electrode current-carrying strip cut into a specified shape, place the electrode current-carrying strip at a specified position on the base material, and bond and solidify the electrode current-carrying strip to the base material through a hot pressing process. The electrode current-carrying strip forms an electrical connection with the heating layer through the conductive layer.

[0067] The electrode current-carrying bar in this embodiment adopts a copper electrode with nickel plating on the surface. The electrode current-carrying bar is used to connect to the power supply, and then the graphene heating layer converts the electrical energy into heat energy and releases it outward. In this embodiment, the electrode current-carrying bar is cut into the required shape and size. The shape of the electrode current-carrying bar matches the shape of the conductive layer printed in the previous step. Each electrode current-carrying bar is stacked to the position of the corresponding conductive layer and completely covers the conductive layer. The stacked material is placed in a hot pressing mold, and then the mold is placed in a preheated hot press. According to the characteristics and requirements of the material, appropriate temperature and pressure are applied and maintained for a certain time. During the hot pressing process, heat and pressure will combine the electrode material with the substrate. After the hot pressing is completed, the mold is removed from the hot press and the material is allowed to cool and solidify. This helps to ensure that the electrode material is firmly bonded to the substrate and form a stable electrode structure.

[0068] S5: Prepare nanofibers and / or fiber composite materials as heat storage slow-release materials, and evenly stack them on the surface of a base material comprising a heating layer, a conductive layer, and electrode current-carrying strips; then combine and solidify the heat storage slow-release material with the base material through a hot pressing process to form a heat storage slow-release layer.

[0069] In this embodiment, the heat storage slow-release layer has the function of accumulating heat and slowly releasing it, which plays a role in maintaining the constant heat generation of the graphene heating layer. During the processing, the flexible substrate and the heat storage slow-release layer are stacked. Ensure that the heat storage slow-release layer is in close contact with the substrate. Place the stacked material in a hot pressing mold, and then place the mold into a preheated hot press. According to the characteristics and requirements of the material, apply appropriate temperature and pressure and maintain them for a certain time. During the hot pressing process, heat and pressure will combine the heat storage slow-release material with the substrate. After the hot pressing is completed, remove the mold from the hot press and allow the material to cool and solidify. This helps to ensure that the hot pressing slow-release layer is firmly bonded to the substrate.

[0070] S6: placing chitosan films on both sides of the base material forming the heat storage slow-release layer or on one side close to the heat storage slow-release layer, and then combining the chitosan film and the base material having the heat storage slow-release layer through a hot pressing process and curing to form a protective layer.

[0071] The obtained composite film material with a protective layer is an environmentally friendly graphene heating film. Depending on the number of layers of the chitosan film, the prepared products are divided into two types: single-sided coating and double-sided coating.

[0072] In a more optimized solution of this embodiment, an antibacterial agent may be added to the renewable cellulose, or the final produced base material may be subjected to a specific surface treatment so that the graphene heating film using the base material has antibacterial properties.

[0073] Example 2

[0074] Based on the solution of Example 1, this embodiment provides an environmentally friendly graphene heating film, and the functional film material is prepared by the preparation method of the environmentally friendly graphene heating film in Example 1. The environmentally friendly graphene heating film provided in this embodiment is divided into two typical structures: single-sided film type and double-sided film type.

[0075] like Figure 2 As shown, the single-sided coated graphene heating film includes a base layer 6, an electrode current-carrying strip 3, a heating layer 5, a conductive layer 4, a heat storage slow-release layer 2, and a protective layer 1. The base layer 6 is made of recycled degradable fibers; the base layer 6 serves as an adhesion layer for the functional layers thereon. The heating layer 5 is located on the base layer 6 and is solidified from graphene ink. The heating layer 5 is prepared using a printing process, so that various complex patterns can be formed as required. The electrode current-carrying strip 3 is composited with the base material through a hot pressing process and electrically connected to the patterned heating layer 5. The electrode current-carrying strip 3 serves as the input electrode when the heating layer 5 is connected to the power supply through a wire. The conductive layer 4 is printed from a silver paste material, which is located between the electrode current-carrying strip 3 and the heating layer 5 to ensure a stable electrical connection between the two. The heat storage slow-release layer 2 is made of nanofibers or fiber composite materials that can absorb and store heat. In this embodiment, the above materials are coated on the electrode current-carrying strip 3, the heating layer 5, and the conductive layer 4, and then a hot pressing process is used to form the heat storage slow-release layer 2 covering the heating layer 5. The heat absorption and heat storage properties of the heat storage and slow-release layer 2 can, on the one hand, prevent local overheating of the product when the heating layer 5 is powered on, and on the other hand, ensure that the product can still maintain a high temperature for a long time after the heating layer 5 is powered off. Finally, the single-sided coated graphene heating film also includes a chitosan protective layer 1 covering the heat storage and slow-release layer 2.

[0076] The double-sided coated graphene heating film includes a base layer 6, an electrode current carrying strip 3, a heating layer 5, a conductive layer 4, a heat storage slow-release layer 2 and a protective layer 1. Figure 3 As shown, compared with the single-sided film-coated product, the double-sided film-coated product has a chitosan protective layer 1 above the heat storage slow-release layer 2 and below the base layer 6.

[0077] In practical applications, single-sided laminated products have a look and feel similar to textile fabrics, making them suitable for self-heating clothing and accessories, such as scarves and heated vests. Double-sided laminated products, on the other hand, offer greater durability and a longer lifespan, and can withstand harsher operating environments, making them suitable as interlayer materials in various self-heating wearable devices.

[0078] Compared to existing graphene heating films, the base material and protective layer 1 of this embodiment are highly biodegradable, addressing the environmental pollution issues associated with traditional products. This new, environmentally friendly graphene heating film also offers improved flexibility, bending resistance, and stability, and its material is closer to fiber fabrics, thus expanding the functionality and application of graphene heating films.

[0079] Furthermore, the regenerated biodegradable cellulose fabric, chitosan membrane, and graphite used in this embodiment all possess antimicrobial properties. These environmentally friendly materials, coupled with the antimicrobial properties of graphene, significantly enhance the antimicrobial properties of the graphene heating film, addressing the lack of antimicrobial properties found in conventional graphene heating films, such as their base and protective films.

[0080] At the same time, by selecting environmentally friendly regenerated degradable cellulose fabric and chitosan film as the substrate and protective layer 1, respectively, the flexibility and wear resistance of the fabric can be effectively utilized, providing a feasible solution for the subsequent use of the graphene heating film for wearable heating fabrics. The graphene heating film proposed in this invention has more excellent antibacterial properties for wearable fabrics and can better meet people's needs for healthy living. For example, the environmentally friendly graphene heating film provided in this embodiment can be used to make various self-heating cushions, clothing, and various emerging wearable devices.

[0081] The raw material cost of the product provided in this embodiment is low, and the preparation process is very suitable for large-scale industrial production using assembly line equipment, which helps to further reduce production costs and has broad commercial prospects.

[0082] Example 3

[0083] This embodiment provides a self-heating wearable device, which includes an environmentally friendly graphene heating film as described in Example 1, and a power supply module electrically connected to the electrode current-carrying strips in the environmentally friendly graphene heating film. In practical applications, the power supply module is used to provide power to the graphene heating film, which is used to convert electrical energy into thermal energy and output it continuously and stably. Because the graphene heating film used in the self-heating wearable device in this embodiment has soft and skin-friendly properties, it can significantly improve the user experience while ensuring the product's self-heating function.

[0084] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing an environmentally friendly graphene heating film, characterized in that: It includes the following steps: S1: chitosan powder is mixed with a thickener, a cross-linking agent, and a plasticizer in a certain proportion and dissolved in a solvent to obtain a chitosan solution; the chitosan solution is evenly coated on a mold and cured to obtain a chitosan film; S2: Prepare graphene ink, use a fabric made of recycled biodegradable fibers as a base material, print the graphene ink onto the base material through a gravure printing process, then heat and dry it at a constant temperature of 130°C, and cool it back on the wheel to form a patterned heating layer on the base material; S3: Prepare silver paste material and print it onto the substrate material through gravure printing process, then heat and dry it at a constant temperature of 160°C, and then return it to the wheel for cooling, thereby forming a patterned conductive layer on the substrate material; S4: preparing an electrode current-carrying bar cut into a specified shape, placing the electrode current-carrying bar at a specified position on the base material, and combining and curing the electrode current-carrying bar with the base material through a hot pressing process; the electrode current-carrying bar is electrically connected to the heating layer through the conductive layer; S5: preparing nanofibers and / or fiber composite materials as heat storage slow-release materials, and evenly stacking them on the surface of a base material comprising a heat-generating layer, a conductive layer, and an electrode current-carrying strip; then combining and curing the heat storage slow-release materials with the base material through a hot pressing process to form a heat storage slow-release layer; S6: placing chitosan films on both sides of the base material forming the heat storage slow-release layer or on one side close to the heat storage slow-release layer, and then combining the chitosan film and the base material having the heat storage slow-release layer through a hot pressing process and curing to form a protective layer; The obtained composite film material with a protective layer is an environmentally friendly graphene heating film. Depending on the number of layers of the chitosan film, the prepared products are divided into two types: single-sided coating and double-sided coating.

2. The method for preparing the environmentally friendly graphene heating film according to claim 1, wherein: In step S1, the solvent is acetic acid or ethanol; and / or The chitosan solution is solidified by heating or chemical cross-linking.

3. The method for preparing the environmentally friendly graphene heating film according to claim 1, wherein: In step S2, the graphene ink is prepared by fully mixing graphene powder, nanographite, conductive carbon black, and conductive resin with a dispersant in a specified ratio to obtain graphene ink.

4. The method for preparing the environmentally friendly graphene heating film according to claim 1, wherein: In step S2, the regenerated biodegradable fiber used as the base material includes triacetate fiber, viscose fiber, Tencel fiber or cupro fiber; The preparation method of the viscose fiber type base material is as follows: Soaking the cellulose raw material in an alkaline solution to remove impurities and non-cellulose components; The cellulose raw material treated with alkali is soaked in a viscose solution to form viscose fiber; Soak the viscose fiber in a solvent to remove excess viscose and solvent, then filter and wash; The washed fiber material is formed into fibers by spinning or spraying, and then stretched and shaped by rotating centrifugal force or air flow; Finally, the shaped fibers are subjected to heat treatment or chemical cross-linking to complete the curing process, and the cured fibers are woven to produce the desired fabric.

5. The method for preparing the environmentally friendly graphene heating film according to claim 4, wherein: The cellulose raw materials are cotton, hemp, bamboo, straw and bark; and / or The alkaline solution is sodium hydroxide solution; and / or The solvent for soaking the viscose fiber is a ketone or aldehyde solvent.

6. The method for preparing the environmentally friendly graphene heating film according to claim 1, wherein: In steps S2 and S3, graphene ink and silver paste are printed onto the substrate material through a roll-to-roll printer; during the printing process, the graphene ink or silver paste is filled into the grooves in the gravure printing roller. During the printing process, the material in the grooves contacts the substrate material and is then transferred to the substrate material.

7. The method for preparing the environmentally friendly graphene heating film according to claim 1, wherein: In step S5, the electrode current-carrying bar adopts a nickel-plated copper electrode; and / or In steps S1 and S6, the chitosan powder used to prepare the protective film is replaced by a chitosan derivative.

8. An environmentally friendly graphene heating film, characterized by: It is prepared by the preparation method of the environmentally friendly graphene heating film as described in any one of claims 1 to 7, and includes: a base layer made of recycled degradable fibers; an electrode current-carrying strip and a patterned graphene heating layer and a conductive layer located on the base layer; a heat storage slow-release layer covering the electrode current-carrying strip, the heating layer and the conductive layer; and a chitosan protective layer covering only the heat storage slow-release layer or simultaneously covering the heat storage slow-release layer and the base layer.

9. An application of an environmentally friendly graphene heating film, characterized by: A single-sided film-coated product prepared by the preparation method of the environmentally friendly graphene heating film as described in any one of claims 1 to 7 is used as a fabric for preparing self-heating clothing or accessories; or a double-sided film-coated product prepared by the preparation method of the environmentally friendly graphene heating film as described in any one of claims 1 to 7 is used as an interlayer material in a self-heating wearable device.

10. A self-heating wearable device, characterized in that: It includes the environmentally friendly graphene heating film as claimed in claim 8, and a power supply module electrically connected to the electrode current-carrying strips in the environmentally friendly graphene heating film.

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