Sandwich-structure electrothermal film capable of utilizing waste mask and preparation method of sandwich-structure electrothermal film

Abstract

The invention relates to the field of electric heating devices, and discloses a sandwich structure electrothermal film capable of utilizing a waste mask, which comprises a composite heating layer and packaging layers arranged on two sides of the composite heating layer, the composite heating layer comprises an electric heating composite membrane and current collector metal layers arranged on the two sides of the electric heating composite membrane, the electric heating composite membrane comprises an electric heating composite membrane and a mask layer, and the electric heating composite membrane comprises an organic high-molecular polymer, an electric heating material and an organic solvent. The sandwich structure electrothermal film disclosed by the invention has a porous three-dimensional skeleton, has a good conductive network, shows good toughness, rigidity, supporting performance and mechanical strength, reduces the risk of short circuit, improves the safety and prolongs the service life. Compared with a traditional electric heating film, due to the fact that the waste mask is used as the raw material, pollution to the environment is reduced, the negative influence of plastic waste on the ecological environment is relieved, the concept of sustainable development is met, and high practical value and wide application prospects are achieved.

Description

Technical Field

[0001] The invention relates to the field of electric heating devices, and in particular to a sandwich structure electric heating film capable of utilizing discarded masks and a preparation method thereof. Background Art

[0002] Electric heating film is an emerging electric heating material system, generally composed of polymers, carbon materials, and inorganic materials. Compared with traditional metal and ceramic electric heating materials, electric heating film has unique advantages such as flexibility, large heating area, high electric heating efficiency, lightness, and environmental friendliness. These characteristics make electric heating film have broad application prospects in many fields, such as building heating, car seat heating, and household appliance heating.

[0003] Although polymer composite electric heating films show good application prospects, the mechanical properties of their thin films are relatively poor. During production, transportation and use, the electric heating films will inevitably be bent or squeezed by external forces, resulting in damage to the material. The electric heating layer may be rolled and thinned, thereby reducing its service life. In addition, the reduction in the dielectric constant of the damaged area may lead to electrical breakdown, causing short circuits and safety risks, which limits its promotion in practical applications.

[0004] At the same time, the application of electric heating films also faces the dual challenges of material costs and environmental impacts. The raw materials of traditional electric heating films are mostly synthetic polymers, which not only makes the production cost high, but also imposes a certain burden on the environment. According to relevant data, billions of discarded masks are produced every month in the world. The main component of these masks, polypropylene, is difficult to degrade in the environment, further exacerbating the ecological crisis. These materials take decades or even hundreds of years to completely decompose, causing long-term pollution to soil and water bodies. A large number of discarded masks are discarded in waters such as the ocean, which has a serious impact on the marine ecosystem. The appearance of the mask is similar to that of a jellyfish, which can be easily eaten by marine life, leading to digestive tract diseases and even death. In addition, the microplastics produced by the decomposition of the mask will also enter the food chain, posing a potential threat to marine life and human health. Therefore, it is particularly urgent to find a sustainable solution.

[0005] Therefore, the development of electric heating film materials with sustainable development, low cost, supporting performance, safety and reliability, high mechanical strength, stable heating and long life is of great significance to the development and application of new electric heating devices. Summary of the invention

[0006] The present invention is to solve the deficiencies in the prior art, and therefore provides a sandwich structure electric heating film that can utilize discarded masks and a preparation method thereof; one of the purposes of the present invention is to provide a sandwich structure electric heating film that can utilize discarded masks, the meltblown cloth layer in the discarded masks has a good three-dimensional rigid skeleton, presents high mechanical strength, supporting performance, fatigue resistance and bending resistance, and reduces the risk of electrical breakdown; the second purpose of the present invention is to provide a sustainable development method to make full use of discarded masks, which not only helps to effectively reduce production costs, but also can significantly reduce environmental burdens.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a sandwich-structured electric heating film that can utilize discarded masks, comprising a composite heating layer and an encapsulation layer arranged on both sides of the composite heating layer; the composite heating layer comprises an electric heating composite membrane sheet and a current collector metal layer arranged on both sides of the electric heating composite membrane sheet, the electric heating composite membrane sheet comprises an electric heating composite membrane and a mask layer, and the electric heating composite membrane comprises an organic high molecular polymer, an electric heating material and an organic solvent.

[0008] Preferably, the encapsulation layer is at least one of epoxy resin, polyester, polyurethane, silicone resin, polyimide alkyd resin, polyimide, polybutadiene, polystyrene, polypropylene, polycarbonate, polytetrafluoroethylene and silicone rubber.

[0009] Preferably, the current collector metal layer is one or more of copper and aluminum.

[0010] Preferably, the mask layer is a discarded mask or a meltblown cloth layer in a mask.

[0011] Preferably, the meltblown cloth layer is at least one of polypropylene, polyurethane or polylactic acid.

[0012] Preferably, the organic high molecular polymer is at least one of thermoplastic polyurethane, polyvinylidene fluoride, epoxy resin, polyacrylonitrile and ABS resin.

[0013] Preferably, the electrothermal material is at least one of a carbon material and a conductive metal material.

[0014] Preferably, the organic solvent is dimethylacetamide.

[0015] In a second aspect, the present invention provides a method for preparing a sandwich structure electric heating film that can utilize discarded masks, characterized in that it comprises the following steps: S1: dissolving an organic high molecular polymer in an organic solvent, and preparing a high molecular polymer glue by mechanical stirring under heating conditions; S2: adding an appropriate amount of electric heating material to the high molecular polymer glue prepared in S1, and mixing the electric heating material and the high molecular polymer glue thoroughly and evenly through mechanical stirring to form an electric heating film slurry; S3: pouring the electric heating film slurry on the meltblown fabric layer of the discarded mask, pouring it twice in both directions, and curing it at high temperature; S4: sticking the double-sided current collector conductive tape to the surface of the electric heating composite film in step S3 to form a composite electric heating film heating layer; S5: Using a plastic sealing machine to plastic seal the outer surface of the composite heating layer prepared in step S4, the thickness of the packaging layer is 1-5 cm.

[0016] Preferably, in step S3, the curing temperature is 80-100° C., and the curing time is 10-24 h.

[0017] Compared with the prior art, the present invention has the following beneficial effects: Using the meltblown cloth layer of discarded masks as part of the electric heating film realizes the reuse of resources, which is helpful for environmental protection and reducing waste disposal costs. The mask layer provides a large surface area due to the gaps between the capillary fibers, which can well adsorb high molecular polymers, electric heating materials and organic solvents, which provides mechanical support and thermal and chemical stability for the electric heating film. At the same time, the sandwich structure ensures the stability and durability of the electric heating film. The sandwich structure contains multiple layers of materials with different thermal conductivity, which can effectively block the heat transfer path between these layers, thereby reducing the heat conduction efficiency; the different material layers in the sandwich structure can also support each other, have high thermodynamic stability, can resist the influence of external thermal stress, and are not prone to deformation or failure; at the same time, the sandwich structure can save space and materials while ensuring performance through the superposition and combination of multiple layers of materials.

[0018] Furthermore, materials such as epoxy resin and polyester have good insulation, heat resistance and corrosion resistance, which can protect the electric heating film from damage by the external environment and increase the service life of the electric heating film.

[0019] Furthermore, metals such as copper and aluminum have good electrical and thermal conductivity, which can effectively convert electrical energy into thermal energy while ensuring uniform heating of the electric heating film.

[0020] Furthermore, discarded masks or the meltblown cloth layer therein, as part of the electric heating film, not only realize waste utilization, but the meltblown cloth layer also has certain filtering and barrier properties, which can enhance the functionality of the electric heating film.

[0021] Furthermore, materials such as polypropylene, polyurethane or polylactic acid have good mechanical properties and thermal stability, and small fiber diameter, which can improve the heating efficiency and uniformity of the electric heating film.

[0022] Furthermore, materials such as thermoplastic polyurethane and polyvinylidene fluoride have good adhesion and formability, can form a good combination with the electric heating material, and have certain thermal stability and electrical insulation.

[0023] Furthermore, carbon materials and conductive metal materials such as graphite, silver, etc. have good electrical conductivity and thermal radiation properties, and can efficiently convert electrical energy into thermal energy, thereby improving the heating efficiency of the electric heating film.

[0024] Furthermore, dimethylacetamide as a solvent can effectively dissolve organic high molecular polymers to form a uniform glue solution, which is helpful for the preparation of electric heating film slurry and the optimization of the performance of the electric heating film.

[0025] On the other hand, from the perspective of the preparation method, the present invention prepares the electric heating film slurry by mixing an organic high molecular polymer, an electric heating material and an organic solvent, then pouring it on a meltblown cloth layer and solidifying it, and finally pasting a current collector metal layer and a packaging layer to form a sandwich structure electric heating film. This method is simple and easy to implement, and can effectively prepare an electric heating film with excellent performance.

[0026] Furthermore, appropriate curing temperature and duration can ensure that the organic polymer in the electric heating film slurry is fully cross-linked and cured to form a stable structure, while avoiding overheating that may cause the material performance to deteriorate. This helps to improve the heat resistance, stability and service life of the electric heating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 This is a schematic diagram of a sandwich structure electric heating film that can utilize discarded masks obtained in Example 1; Figure 2 A schematic diagram of an electrothermal composite membrane sheet obtained in Example 1 that can utilize a sandwich structure electrothermal membrane of discarded masks; Figure 3 The temperature-time curve of the sandwich structure electric heating film obtained in Example 1 that can utilize discarded masks and is electrically heated at a DC voltage of 12V; Among them, 1. packaging layer; 2. current collector metal layer; 3. electric heating composite membrane; 4. mask layer; 5. electric heating composite membrane. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] Embodiment 1: Embodiment 1 provides a sandwich structure electric heating film that can utilize discarded masks and a preparation method thereof, and the specific steps are as follows: (1) dissolving 10 parts by weight of polyimide powder into 70 parts by weight of NN dimethylacetamide solution, and preparing a PI-DMAc solution by mechanical stirring at 60° C.; (2) adding 20 parts by weight of graphite to the PI-DMAc solution prepared in step (1), and placing the solution on a 60° C. constant temperature magnetic stirrer for stirring and dispersing at a certain speed to form an electric heating film slurry; (3) Pour the electric heating film slurry onto the meltblown fabric layer of the discarded mask, pour it twice in both directions, and cure it at 100°C for 10 h; The fiber diameter of the meltblown cloth layer is 1-5μm, with many voids, fluffy structure, good wrinkle resistance, and ultra-fine fibers with unique capillary structure increase the number and surface area of ​​fibers per unit area, so that the meltblown cloth layer can adsorb high molecular polymers and electric heating materials. The meltblown cloth layer has excellent thermal insulation. Since the thermal conductivity of air is much smaller than that of ordinary fibers, the air in the pores of the meltblown cloth layer makes its thermal conductivity smaller, so it has a good heat insulation and warmth-keeping effect. Common materials for meltblown cloth include PP (polypropylene), PET (polyester), PA (nylon), etc. Among them, PP material is the preferred material for manufacturing meltblown cloth due to its good physical properties and chemical stability. High-quality meltblown cloth is usually made of PP material, and the weight is generally more than 25 grams. Such material and quality can ensure that the meltblown cloth layer has a long service life.

[0032] (4) Adhere the double-sided current collector conductive tape to the surface of the electric heating composite film 3 in step (3) to form a composite electric heating film heating layer; Double-sided current collector conductive tape is usually composed of a composite of conductive materials (such as metal foil, metal grid, carbon black, etc.) and tape materials. These conductive materials can ensure that the tape conducts electricity stably under various temperature and humidity conditions, and has good adhesion, corrosion resistance, heat resistance, excellent processability and flexibility, and is very suitable for the preparation of electric heating films.

[0033] (5) Using a plastic sealing machine, plastic seal the two sides of the composite heating layer prepared in step (4), and the thickness of the packaging layer 1 is 1 cm, so that a "sandwich" structure electric heating film that can utilize discarded masks is obtained.

[0034] The thickness of the encapsulation layer 1 is selected as the minimum value within the range of 1-5 cm, which is beneficial to reducing the thickness of the encapsulation layer, increasing the heating rate of the electric heating film, and reducing the heat storage of the electric heating film.

[0035] The resistance and electrothermal performance of the sandwich structure electrothermal film made of discarded masks prepared in Example 1 were tested. The resistance was 87 Ω·mm. The electrical performance test was as follows: Figure 3 As shown, the electric heating film reaches a constant temperature within 100s under a voltage of 12V, with a maximum temperature of 50°C, and can work stably at the highest temperature.

[0036] Embodiment 2: Embodiment 2 provides a sandwich structure electric heating film that can utilize discarded masks and a preparation method thereof, and the specific steps are as follows: (1) dissolving 15 parts by weight of thermoplastic polyurethane particles into 70 parts by weight of NN dimethylacetamide solution, and preparing a TPU-NMP solution by mechanical stirring at 60° C.; (2) adding 15 parts by weight of graphite to the TPU-NMP solution prepared in step (1), and placing the solution on a 60° C. constant temperature magnetic stirrer for stirring and dispersing at a certain speed to form an electric heating film slurry; (3) Pour the electric heating film slurry onto the meltblown fabric layer of the discarded mask, pour it twice in both directions, and cure it at 80°C for 12 h; (4) Adhere the double-sided current collector conductive tape to the surface of the electric heating composite film 3 in step (3) to form a composite electric heating film heating layer; (5) Using a plastic sealing machine, plastic seal the two sides of the composite heating layer prepared in step (4), and the thickness of the packaging layer 1 is 1 cm, so that a "sandwich" structure electric heating film that can utilize discarded masks is obtained.

[0037] The thickness of the encapsulation layer 1 is selected as the minimum value within the range of 1-5 cm, which is beneficial to reducing the thickness of the encapsulation layer, increasing the heating rate of the electric heating film, and reducing the heat storage of the electric heating film.

[0038] The sandwich structure electric heating film made of discarded masks prepared in Example 2 was tested for resistance and electric heating performance. The resistance was 60 Ω·mm. The electric heating film reached a constant temperature within 70 seconds under a voltage of 12V, with a maximum temperature of 80°C, and could work stably at the highest temperature.

[0039] Embodiment 3: Embodiment 3 provides a sandwich structure electric heating film that can utilize discarded masks and a preparation method thereof, and the specific steps are as follows: (1) 15 parts by weight of polyacrylonitrile particles were dissolved in 70 parts by weight of N-N-dimethylacetamide solution, and PAN-NMP solution was prepared by mechanical stirring at 60° C.; The dimethylacetamide can also be replaced by dimethylformamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxide as an organic solvent; dimethylformamide is miscible with water and most organic solvents, and has good solubility for a variety of resins; N-methyl-2-pyrrolidone is also a polar aprotic solvent, and has good solubility for a variety of organic and inorganic substances; dimethyl sulfoxide has the characteristics of strong polarity, high boiling point, and low volatility, and can dissolve a large number of organic compounds, inorganic salts, and metal ions.

[0040] (2) adding 15 parts by weight of graphite to the PAN-NMP solution prepared in step (1), and placing the solution on a 60° C. constant temperature magnetic stirrer for stirring and dispersing at a certain speed to form an electric heating film slurry; (3) Pour the electric heating film slurry onto the meltblown fabric layer of the discarded mask, pour it twice in both directions, and cure it at 85°C for 12 h; (4) Adhere the double-sided current collector conductive tape to the surface of the electric heating composite film 3 in step (3) to form a composite electric heating film heating layer; (5) Using a plastic sealing machine, plastic seal the two sides of the composite heating layer prepared in step (4), and the thickness of the packaging layer 1 is 1 cm, so that a "sandwich" structure electric heating film that can utilize discarded masks is obtained.

[0041] The thickness of the encapsulation layer 1 is selected as the minimum value within the range of 1-5 cm, which is beneficial to reducing the thickness of the encapsulation layer, increasing the heating rate of the electric heating film, and reducing the heat storage of the electric heating film.

[0042] The sandwich structure electric heating film made of discarded masks prepared in Example 3 was tested for resistance and electric heating performance. The resistance was 115 Ω·mm. The electric heating film reached a constant temperature within 80 seconds under a voltage of 12V, with a maximum temperature of 90°C, and could work stably at the highest temperature.

[0043] Based on the three embodiments, when selecting a substrate, choose a suitable polymer substrate according to the needs of the application scenario. If high temperature stability is required, polyimide can be selected; if flexibility and wear resistance are required, thermoplastic polyurethane can be selected; if high strength and corrosion resistance are required, polyacrylonitrile can be selected. When selecting the optimized curing conditions, the internal structure and performance of the electric heating film are optimized by adjusting the curing temperature and time. Higher curing temperatures may help to form a denser film structure, but may also cause polymer degradation or aging; longer curing times may help to more fully remove solvents and form a stable structure, but will also increase production costs.

[0044] When using heating films, it is also necessary to consider balancing the electric heating performance. Balance the resistance of the electric heating film, the time to reach a constant temperature, and the maximum temperature according to the application requirements. Lower resistance may mean higher conductivity and lower energy consumption, but it may also lead to higher temperatures and faster heating rates; higher maximum temperatures may be suitable for application scenarios that require high temperature heating, but may also increase energy consumption and safety risks.

[0045] The discarded masks used in the present invention have undergone professional medical treatment to effectively remove microorganisms and residual stains on the surface; if it is an unused mask, it does not need to be cleaned and can be used to prepare the sandwich structure electric heating film in the present invention. Masks are usually made of multiple layers of materials, including meltblown fabrics, non-woven fabrics, etc. The thermal stability, conductivity and mechanical properties of these materials may vary depending on the brand, type and manufacturing process. When preparing the sandwich structure electric heating film, these properties of the mask materials need to be evaluated to ensure that they can meet the functional requirements of the electric heating film.

[0046] The use of discarded masks to prepare electric heating films may involve the issue of medical waste treatment and reuse. The environmental friendliness of the entire process must be ensured to avoid potential health hazards. The safety of the electric heating film is also crucial and must undergo rigorous testing and certification to ensure that it does not cause harm to the human body during use. The reuse of discarded masks helps reduce the amount of waste, but the environmental impact of the entire treatment process also needs to be considered. For example, the disinfection and cleaning process may generate wastewater or exhaust gas, which needs to be properly handled.

[0047] Regarding other improvement directions of electric heating films, you can choose to adjust the preparation process and design structure to improve its mechanical properties and reliability. For example, the mechanical strength of the electric heating film can be improved by using a multi-layer reinforcement structure or adding reinforcing fibers; the heating effect and service life can be improved by optimizing the distribution and thickness of the electric heating layer. On the other hand, they are also actively looking for environmentally friendly materials to replace traditional synthetic polymers. For example, the use of recycled materials such as polypropylene in discarded masks to prepare electric heating films; the development of electric heating films using bio-based or degradable materials, etc. These innovative solutions not only help to reduce the production cost and environmental impact of electric heating films, but also provide a strong guarantee for their application in a wider range of fields. In addition, promoting the integration and innovation of electric heating films with other technologies will also bring new development opportunities and challenges to them. For example, combining electric heating films with smart sensors, the Internet of Things and other technologies can achieve more intelligent and personalized electric heating solutions to meet people's higher demands for comfort, energy saving and environmental protection.

[0048] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0049] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.

Claims

1. A sandwich structure electric heating film that can utilize discarded masks, characterized in that: It comprises a composite heating layer and a packaging layer (1) arranged on both sides of the composite heating layer; the composite heating layer comprises an electric heating composite membrane (3) and a current collector metal layer (2) arranged on both sides of the electric heating composite membrane (3); the electric heating composite membrane (3) comprises an electric heating composite film (5) and a mask layer (4); the electric heating composite film (5) comprises an organic high molecular polymer, an electric heating material and an organic solvent.

2. The sandwich structure electric heating film that can utilize discarded masks according to claim 1 is characterized in that: The encapsulation layer (1) is at least one of epoxy resin, polyester, polyurethane, silicone resin, polyimide alkyd resin, polyimide, polybutadiene, polystyrene, polypropylene, polycarbonate, polytetrafluoroethylene and silicone rubber.

3. The sandwich structure electric heating film that can utilize discarded masks according to claim 1 is characterized in that: The current collector metal layer (2) is one or more of copper and aluminum.

4. The sandwich structure electric heating film that can utilize discarded masks according to claim 1 is characterized in that: The mask layer (4) is a discarded mask or a meltblown fabric layer in a mask.

5. The sandwich structure electric heating film that can utilize discarded masks according to claim 4 is characterized in that: The meltblown fabric layer is at least one of polypropylene, polyurethane or polylactic acid.

6. The sandwich structure electric heating film that can utilize discarded masks according to claim 1, characterized in that: The organic high molecular polymer is at least one of thermoplastic polyurethane, polyvinylidene fluoride, epoxy resin, polyacrylonitrile and ABS resin.

7. The sandwich structure electric heating film that can utilize discarded masks according to claim 1, characterized in that: The electric heating material is at least one of a carbon material and a conductive metal material.

8. The sandwich structure electric heating film that can utilize discarded masks according to claim 1, characterized in that: The organic solvent is dimethylacetamide.

9. A method for preparing a sandwich structure electric heating film that can utilize discarded masks according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: dissolving an organic high molecular polymer in an organic solvent, and preparing a high molecular polymer glue by mechanical stirring under heating conditions; S2: adding an appropriate amount of electric heating material to the high molecular polymer glue prepared in S1, and mixing the electric heating material and the high molecular polymer glue thoroughly and evenly through mechanical stirring to form an electric heating film slurry; S3: pouring the electric heating film slurry on the meltblown fabric layer of the discarded mask, pouring it twice in both directions, and curing it at high temperature; S4: sticking the double-sided current collector conductive tape to the surface of the electric heating composite film (3) in step S3 to form a composite electric heating film heating layer; S5: Use a plastic sealing machine to plastic seal the outer surface of the composite heating layer prepared in step S4, and the thickness of the packaging layer (1) is 1-5 cm.

10. A method for preparing a sandwich structure electric heating film that can utilize discarded masks according to claim 9, characterized in that: In step S3, the curing temperature is 80-100° C., and the curing time is 10-24 h.

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