A graphene electric heating film and its preparation method and application

Abstract

The present invention discloses a graphene electric heating film, its preparation method, and applications. The graphene electric heating film comprises an electric heating composite material layer obtained by curing a uniform slurry consisting of a graphene composite suspension, a composite resin suspension, a silane coupling agent, and vitamin C. The graphene composite suspension comprises graphene nanosheets, conductive carbon black, ammonium polyacrylate, sodium dodecylbenzenesulfonate, and silicone oil, while the composite resin suspension comprises a flame-retardant epoxy resin and a curing agent. The electric heating film provided by the present invention is compact and lightweight, with a bendable angle of up to 90°, showing promising wearable applications. Furthermore, the preparation method is simple, the electrothermal radiation conversion efficiency is high, and the biosafety is high. It has demonstrated promising results in promoting wound repair, preventing peritoneal adhesions, and promoting hair growth.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and specifically relates to a graphene electric heating film and a preparation method thereof, as well as its application in technical fields such as promoting wound repair, preventing abdominal adhesions and promoting hair growth. Background Art

[0002] As a new polymer material, graphene can, when powered, radiate electrical energy via far-infrared radiation through the Brownian motion of carbon atoms. When the frequency of these rays aligns with the frequencies of cellular and water molecules in the human body, they induce physiological, thermal, and resonance effects. The energy is absorbed by human tissue, thereby promoting blood circulation, enhancing metabolism, reducing inflammation, and strengthening the body's immunity and the regenerative capacity of biological tissues, achieving the goal of preventing and treating diseases. Therefore, electrothermal composite materials using graphene as one of the raw materials can, when powered, convert electrical energy into far-infrared radiation that radiates in all directions, while simultaneously transferring heat energy to objects in contact, generating a range of biological and physical functions.

[0003] Graphene electric heating composites are currently promising functional materials, demonstrating significant advantages and potential for development in numerous fields, including home heating, agriculture, aviation, and healthcare. Currently, most common graphene heating materials on the market are rigid, limiting their application. The few graphene-based flexible electric heating films available today typically attach graphene to flexible substrates through dip coating, in-situ chemical deposition, or brush coating. However, these methods often require high graphene content, are expensive, and are prone to shedding, hindering their commercial application.

[0004] Moreover, current graphene electrothermal composite materials generally have disadvantages such as low electricity conversion efficiency, wide radiation wavelength range, and large usage area. There is no solution for the research and development of miniaturized, flexible, and wearable graphene electrothermal films that can meet medical needs. Summary of the Invention

[0005] In response to the problems in the prior art, the present invention provides a graphene electric heating film and a preparation method thereof. The electric heating film has the advantages of small amount of graphene used, low cost, simple preparation method, high electric-thermal radiation conversion efficiency, large bending angle, etc., and has positive effects in promoting wound repair, preventing abdominal adhesions, and promoting hair growth. Therefore, it has good application prospects in the field of wearable medical devices.

[0006] The scheme of the present invention is as follows:

[0007] The first aspect of the present invention provides a graphene electric heating film, which includes an electric heating composite material layer and a fiber membrane layer bonded to the upper and lower surfaces of the electric heating composite material layer. The electric heating composite material layer is specifically obtained by curing a uniform slurry consisting of a graphene composite suspension, a composite resin suspension, a silane coupling agent and vitamin C; wherein,

[0008] The graphene composite suspension comprises, by weight, 20 to 40 parts of a graphene nanosheet suspension (with a solid content of 17 to 22%), 20 to 40 parts of conductive carbon black, 2 to 4 parts of ammonium polyacrylate, 2 to 4 parts of sodium dodecylbenzenesulfonate, and 2 to 4 parts of silicone oil.

[0009] The composite resin suspension comprises, by weight, 100 to 200 parts of flame retardant epoxy resin, 20 to 40 parts of curing agent, 1.5 to 3 parts of leveling agent, 1 to 2 parts of dispersant and 1 to 2 parts of organosilicon defoaming agent.

[0010] In the above-mentioned graphene electric heating film, an electrode layer is also attached to the graphene electric heating film to facilitate supplying power to the graphene electric heating film so that it can convert electrical energy into far-infrared radiation.

[0011] In the above-mentioned graphene electric heating film, the weight ratio of the graphene composite suspension to the composite resin suspension, the silane coupling agent and the vitamin C is preferably 1:1:0.01:0.06~0.1.

[0012] In the graphene electric heating film, the graphene in the graphene nanosheet suspension is 3 to 10 layers of few-layer graphene with a particle size of 5 to 20 μm, and the particle size of the carbon black is 5 to 30 nm.

[0013] In the above-mentioned graphene electric heating film, the combination of polyacrylamide and sodium dodecylsulfonate in the graphene composite suspension helps to evenly disperse the graphene nanosheets and carbon black, and after mixing with the composite resin suspension, the polyacrylamide can work together with the epoxy resin to synergistically bond the graphene and carbon black.

[0014] In the above-mentioned graphene electric heating film, the flame-retardant epoxy resin can be a N-containing flame-retardant epoxy resin and / or a P-containing flame-retardant epoxy resin; preferably, the flame-retardant epoxy resin is composed of 50 to 100 parts of a N-containing flame-retardant epoxy resin and 50 to 100 parts of a P-containing flame-retardant epoxy resin; the epoxy resin plays a bonding role in the composite material, and can avoid combustion after current overload, which helps to ensure safety and fire prevention.

[0015] In the above-mentioned graphene electric heating film, the curing agent is used to promote the curing of the epoxy resin, and an amide-amine room temperature curing type can be selected, such as type 651; the leveling agent has a penetration-promoting effect, and the present invention preferably uses a polyoxyethylene ether surfactant as a leveling agent; the dispersant is mainly used to increase the compatibility of oily and aqueous components in the same system, such as PSI-500 silane coupling agent.

[0016] In the above graphene electric heating film, the fiber membrane layers bonded to the upper and lower surfaces of the electric heating composite material layer may be polyester fiber membranes.

[0017] In the above-mentioned graphene electric heating film, the thickness of the graphene electric heating film is preferably 50-300 μm, and the maximum diameter of the graphene electric heating film is preferably 2-30 cm.

[0018] A second aspect of the present invention provides a method for preparing the above-mentioned graphene electric heating film, which specifically comprises the following operations:

[0019] (1) Preparation of graphene composite suspension: 20-40 parts of graphene nanosheet suspension, 20-40 parts of conductive carbon black, 2-4 parts of ammonium polyacrylate, 2-4 parts of sodium dodecylbenzenesulfonate and 2-4 parts of silicone oil were added to 200 parts of water in sequence, mixed and centrifuged to remove 90% of the water.

[0020] (2) Preparation of composite resin suspension: Mix 100-200 parts of flame retardant epoxy resin, 20-40 parts of curing agent, 1.5-3 parts of leveling agent, 1-2 parts of dispersant and 1-2 parts of silicone defoamer, and adjust the pH to 8.0-8.5;

[0021] (3) The graphene composite suspension and the composite resin suspension are mixed and a silane coupling agent and vitamin C are added, the mixture is stirred and ground, and the resulting slurry is coated between two layers of fiber membranes and cured.

[0022] In the above preparation method, the treatment conditions for mixing the components in step (1) are preferably: stirring and mixing at a stirring speed of 12,000 to 15,000 rpm for 0.5 to 0.8 h. In addition, the addition of excess water in step (1) facilitates the mixing of the materials, but in order to mix with the composite resin suspension, it is necessary to concentrate and remove excess water; the silicone oil added to the graphene composite suspension plays a role in reducing surface tension, reducing stirring friction and having a hydrophobic effect. In addition to facilitating uniform mixing, it is also beneficial for the subsequent removal of excess water.

[0023] In the above preparation method, the treatment conditions for mixing the components in step (2) are preferably: stirring and mixing at a stirring speed of 1000-1500 rpm for 0.5-1 h.

[0024] In the above preparation method, the operating parameters of the stirring and mixing in step (3) are preferably: stirring at a stirring speed of 12000-15000 rpm for 1-1.2 h; grinding can be specifically performed using a three-roll grinder to grind the mixture into a uniform and fine slurry.

[0025] In the above preparation method, adjusting the pH of the composite resin suspension to a slightly alkaline pH (8.0-8.5) facilitates crosslinking of the materials in the mixed system formed by the graphene composite suspension and the composite resin suspension, and promotes uniform dispersion of the graphene in the resin. Specifically, in one embodiment of the present invention, diethylenetriamine is used as the pH adjuster.

[0026] In the above preparation method, the vitamin C added in step (3) can reduce the mixed slurry gently and slowly, avoiding the generation of oxidized groups during the cross-linking reaction, which is beneficial to reducing the generation of graphene oxide and making the graphene sheets π-π Covalent stacking forms an ordered layered structure; at the same time, vitamin C hinders the rapid formation of a hydrophobic surface, which is beneficial for the silane coupling agent to promote the cross-linking of the graphene composite suspension and the composite resin suspension; in addition, vitamin C can also avoid damage to human skin by eliminating acidic residues in the slurry.

[0027] In the above preparation method, the curing conditions in step (3) are preferably: drying at 110-130°C for 20-24 hours.

[0028] The third aspect of the present invention provides the application of the graphene electric heating film prepared by the present invention in wearable products, especially in wearable medical device products. As shown in the embodiment data of the present invention, the graphene electric heating film prepared by the present invention can effectively promote the healing of abdominal wall wounds in rats, prevent postoperative abdominal adhesions in rats, and promote abdominal hair growth in rats.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The graphene electrothermal film synthesized in this invention is compact and lightweight, with a thickness of 50-300 μm, a maximum diameter of 2-30 cm, and a bendable angle of up to 90°, showing promising wearable applications. Furthermore, the film's preparation process is simple, cost-effective, and requires mild reaction conditions. Its electrothermal radiation conversion efficiency reaches up to 83%, and its far-infrared radiation wavelength ranges from 5-15 μm. This makes it suitable for widespread use in biological applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a scanning electron microscope cross-sectional view of the graphene electric heating film prepared in the present invention;

[0032] Figure 2The graphene electric heating film prepared by the present invention is a physical object and a thermal image;

[0033] Figure 3 This is a curve diagram of the radiation wavelength of the graphene electric heating film prepared by the present invention;

[0034] Figure 4 This is a diagram showing the flexibility of the graphene electric heating film prepared by the present invention;

[0035] Figure 5 XRD patterns of the graphene electric heating film prepared in the present invention and the graphene electric heating film prepared in Comparative Example 1;

[0036] Figure 6 This is a diagram showing the effect of the graphene electric heating film prepared based on the present invention on promoting the healing of abdominal wall wounds in rats;

[0037] Figure 7 This is a diagram showing the effect of using the graphene electric heating film prepared based on the present invention to prevent postoperative abdominal adhesion in rats;

[0038] Figure 8 This is a diagram showing the effect of the graphene electric heating film prepared based on the present invention on promoting the growth of abdominal hair in rats;

[0039] Figure 9 This is an H&E staining image of rat skin after irradiation with the graphene electric heating film prepared by the present invention. DETAILED DESCRIPTION

[0040] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0041] Unless otherwise specified, all examples were prepared under conventional experimental conditions or the conditions recommended by the manufacturer's instructions. All reagents and materials used were commercially available unless otherwise specified.

[0042] Example 1

[0043] 20 parts of a few-layer graphene nanosheet suspension (17% solids content), 20 parts of conductive carbon black, 2 parts of ammonium polyacrylate, 2 parts of sodium dodecylbenzenesulfonate, and 2 parts of silicone oil were added to 200 mL of deionized water. The mixture was then mixed in a high-speed blender at 15,000 rpm for 0.5 h. The mixture was filtered to remove 90% of the water to obtain a graphene composite suspension.

[0044] Mix 100 parts of a phosphorus-containing flame-retardant epoxy resin (halogen-free flame-retardant phosphorus-containing epoxy resin EP0-133), 20 parts of a curing agent (Type 651), 1.5 parts of a leveling agent (fatty amine polyoxyethylene ether), 1 part of a dispersant (PSI-500 silane coupling agent), and 1 part of a silicone defoamer (Kain Chemical BYK-052N). Stir at 1000 rpm for 0.5 h, and then adjust the pH of the resulting suspension to 8.5 with diethylenetriamine. This yields a composite resin suspension.

[0045] 100 parts of the graphene composite suspension, 100 parts of the composite resin suspension, 1 part of a silane coupling agent, and 8 parts of vitamin C were mixed in a high-speed blender at 12,000 rpm for 1 hour. This was then ground on a three-roll mill to produce a uniform, fine composite graphene slurry. The slurry was then coated onto a polyester film and baked in an oven at 120°C for 24 hours. Electrode layers were then attached to both sides to produce the graphene electric heating film.

[0046] Example 2

[0047] In this example, 30 parts of a few-layer graphene nanosheet suspension (solid content 17%) was added to the graphene composite suspension, and the rest was the same as in Example 1.

[0048] Example 3

[0049] In this example, 40 parts of a few-layer graphene nanosheet suspension (solid content 17%) was added to the graphene composite suspension, and the rest was the same as in Example 1.

[0050] Example 4

[0051] Different from Example 1, the preparation process parameters of this example are as follows:

[0052] 20 parts of a few-layer graphene nanosheet suspension (17% solids content), 30 parts of conductive carbon black, 3 parts of ammonium polyacrylate, 4 parts of sodium dodecylbenzenesulfonate, and 2 parts of silicone oil were added to 200 mL of deionized water. The mixture was then mixed in a high-speed blender at 15,000 rpm for 0.8 hours. The mixture was filtered to remove 90% of the water to obtain a graphene composite suspension.

[0053] Mix 50 parts of an N-containing flame-retardant epoxy resin, 50 parts of a P-containing flame-retardant epoxy resin, 25 parts of a curing agent, 2 parts of a leveling agent, 2 parts of a dispersant, and 2 parts of a silicone defoamer. Stir at 1500 rpm for 0.5 h, and then adjust the pH of the resulting suspension to 8.5 with diethylenetriamine. This yields a composite resin suspension.

[0054] 100 parts of the graphene composite suspension, 100 parts of the composite resin suspension, 1 part of a silane coupling agent, and 10 parts of vitamin C were mixed in a high-speed blender at 12,000 rpm for 1 hour. This was then ground on a three-roll mill to produce a uniform, fine composite graphene slurry. The slurry was then coated onto a polyester film and baked in an oven at 125°C for 20 hours. Electrode layers were then attached to both sides to produce the graphene electric heating film.

[0055] The graphene electric heating films prepared in the above embodiments were characterized as follows:

[0056] (1) Scanning electron microscopy experiment of graphene electrothermal film.

[0057] The prepared graphene electric heating film samples were placed under a scanning electron microscope to observe the plane and cross-sectional morphology. The results are shown in the attached figure. Figure 1 As shown, the graphene electric heating film has a thickness of 50 μm, and has a layered structure with uniformly distributed graphene both in the cross section and the plane.

[0058] (2) Physical object and thermal imaging of graphene electric heating film.

[0059] The graphene electric heating film radiates far infrared when powered on (input voltage 42V), and the far infrared thermal imaging state is observed using the FLIR One Pro system. The results are shown in the attached figure. Figure 2 As shown, far-infrared thermal imaging shows that its temperature can rise to 42.4°C within 1 minute. In addition to the rapid temperature response, due to the high thermal conductivity of the graphene electric heating film, a uniformly distributed heat flow was also observed. During the heating process, the high-temperature graphene is the main heat source, which can transfer heat to the surrounding of the human body through radiation and conduction, of which thermal radiation and conduction are both beneficial.

[0060] (3) Radiation wavelength of graphene electric heating film.

[0061] The graphene electric heating film radiates far infrared when powered (input voltage 45V), and the far infrared radiation wavelength is detected using a Fourier transform infrared spectrometer. The results are shown in the attached figure. Figure 3 As shown, the far-infrared emission wavelength range is 5~15μm, with a peak at 8.5μm, which is close to the far-infrared wavelength range of human tissue (8~14μm), indicating that the far-infrared radiation generated by the graphene electrothermal film can be quickly absorbed by human tissue.

[0062] (4) Deformability of graphene electric heating film.

[0063] The prepared graphene electric heating film was folded and bent into different shapes. It was found that the graphene electric heating film has excellent flexibility and can be easily bent into different angles. The results are shown in the attached figure. Figure 4 This suggests it has potential as a wearable device.

[0064] (5) The electric-to-thermal conversion efficiency and power emission rate of graphene electrothermal film.

[0065] In accordance with the inspection requirements of JG / T 286-2010 "Low-Temperature Radiant Heating Film," GB / T 7287-2008 "Test Methods for Infrared Radiant Heaters," and GB / T 4654-2008 "General Technical Requirements for Infrared Radiant Heaters Based on Non-Metallic Substrates," the power emissivity and electrical-radiant power transfer efficiency were tested by the Wuhan National Infrared and Industrial Electric Heating Product Quality Inspection Center. The results showed that the prepared graphene electric heating film achieved an electric-to-heat conversion efficiency of 83% and a normal total emissivity of 0.89. Furthermore, the leakage current, electrical strength, moisture resistance, thermal cycling resistance, and insulation resistance all significantly exceeded the standard requirements.

[0066] Comparative Example 1

[0067] No vitamin C was added to the graphene electric heating film prepared in this example, and the other steps were the same as those in Example 1.

[0068] The graphene electric heating films prepared in Example 1 and this example were analyzed by X-ray diffraction (XRD). The results are as follows: Figure 5 As shown:

[0069] The prepared graphene electric heating film showed a layered structure of filled few-layer graphene sheets, and a few wrinkles were also observed in the SEM image; furthermore, vitamin C avoided the generation of graphene oxidation groups during the reaction process. The X-ray diffraction pattern (XRD) of the graphene electric heating film reduced without vitamin C showed a strong peak at 2θ = 10.7°, while the graphene electric heating film reduced with vitamin C showed a broad peak at 24°, indicating that vitamin C avoided graphene oxidation, and there was π-π superposition between the graphene sheets, forming an ordered layered structure.

[0070] Comparative Example 2

[0071] In this example, 5 parts or 10 parts of a few-layer graphene nanosheet suspension (solid content 17%) were added to the graphene composite suspension, and the rest was the same as in Example 1.

[0072] The physical properties of the graphene electric heating films (with consistent thickness) prepared in Examples 1 to 3 and Comparative Example 2 were tested using a universal material testing machine, and the test results are shown in Table 1. At room temperature (298 K), after 500 consecutive bends at a bending radius of 5 mm, the bending stress of the example remained constant within the system error of the testing machine, indicating that no breakage occurred during the bending process. This is mainly due to the larger amount of graphene nanosheets compared to the comparative example, and the strong interaction force of the π-π bonds between adjacent nanosheet structures. Stress-strain testing found that the graphene film with 40 parts of graphene nanosheet suspension added had the highest strength, with a tensile fracture strength of 192.8±9.8 MPa. The conductivity of the graphene film with 20 parts of graphene nanosheet suspension added was an average of 1800 W∙m −1 ∙K −1 Compared with the comparative example, it is shown that the graphene electric heating film prepared by the present invention has good physical properties.

[0073] Table 1 Physical properties of graphene electric heating films with different graphene nanosheet contents

[0074]

[0075] Example 5 Effect of graphene electric heating film on wound healing

[0076] (1) Establishment of rat abdominal wall wound model.

[0077] To investigate the effect of graphene heating film on promoting abdominal wall wound healing in rats, an abdominal wall wound model simulating abdominal surgery was established in SD rats. Twelve SPF-free SD rats were randomly divided into two groups (control group and FIR group). After the rats were anesthetized with 10% sodium pentobarbital solution, a 4-cm-long wound was made along the linea alba on the abdominal wall using ophthalmic scissors. The wound was then sutured with interrupted 4-0 silk sutures.

[0078] (2) Graphene electrothermal film promotes the healing of abdominal wall wounds in rats.

[0079] Under the same feeding conditions, the control group received no treatment after surgery, while the graphene heating film group FIR received far-infrared radiation treatment with graphene heating film after surgery. With an input power of 36-40V, the radiation was applied to the abdomen for 10 hours every day. After one week, the abdominal wall wound healing of the two groups of rats was observed, and the unhealed area was counted and analyzed. The results are shown in the attached figure. Figure 6 As shown in the figure, the abdominal wall wounds of FIR rats in the graphene electrothermal film group were completely healed, while most of the wounds in the control group were not healed. The difference in wound area between the two groups was statistically significant ( P =0.0037). The results showed that the graphene electrothermal film prepared by this method can promote the healing of abdominal wall wounds.

[0080] Example 6 Application of graphene electric heating film in preventing postoperative abdominal adhesions

[0081] (1) Establishment of a rat model of postoperative cecum-peritoneal adhesion.

[0082] To investigate the efficacy of graphene electrothermal film in preventing postoperative peritoneal adhesions in rats, a cecal-peritoneal adhesion model was established in Sprague-Dawley rats simulating abdominal surgery. Twelve SPF-free Sprague-Dawley rats were randomly divided into two groups (control group and FIR group). After a 12-hour fast, the rats were anesthetized with 10% sodium pentobarbital solution. The cecum was then removed and a 2 × 1 cm area was exposed. Cecal serosa was injured by gauze friction, resulting in punctate hemorrhages but no perforation. The contralateral peritoneum was then scraped to create a 2 × 1 cm defect. 4-0 silk sutures were then used to tie the abraded cecum to the defect. Finally, the abdominal cavity was closed with layer-by-layer sutures.

[0083] (2) Graphene electrothermal film prevents postoperative abdominal adhesion formation in rats.

[0084] Under the same feeding conditions, the control group received no treatment after surgery, while the graphene heating film group FIR received far-infrared radiation treatment with graphene heating film after surgery. Under the input power of 36-40V, the radiation was applied to the abdomen for 10 hours every day. One week later, the abdominal adhesions of the two groups of rats were examined by laparotomy, and the adhesion area was counted and analyzed. The results are shown in the attached figure. Figure 7 As shown in the figure, all rats in the control group developed severe abdominal adhesions, while more than 70% of the FIR rats in the graphene electrothermal film group did not develop abdominal adhesions, and the difference in the area of ​​abdominal adhesions between the two groups was statistically significant ( P =0.0005). The results showed that the graphene electric heating film prepared by this method can prevent the formation of postoperative abdominal adhesions.

[0085] Example 7 Effect of Graphene Heating Film on Hair Growth

[0086] (1) Establishment of the rat abdominal hair loss model

[0087] To investigate the effect of graphene heating film on promoting abdominal hair growth in rats, a SD rat model simulating abdominal hair loss was first established. Twelve SPF-free SD rats were randomly divided into two groups: a control group and a graphene heating film group (FIR). After anesthetizing the rats with 10% sodium pentobarbital solution, an electric shaver and depilatory cream were used to clean a 6×4 cm area of ​​the abdomen, leaving no visible hair.

[0088] (2) Graphene electrothermal film promotes abdominal hair growth in rats

[0089] Under the same feeding conditions, the control group received no treatment after surgery, while the graphene heating film group FIR received far-infrared radiation treatment with graphene heating film after surgery. Under the input power of 36-40V, the radiation was applied to the abdomen for 10 hours every day. After one week, the abdominal hair growth of the two groups of rats was observed, and the abdominal hair growth area was counted and analyzed. The results are shown in the attached figure. Figure 8 As shown in the figure, the hair growth area of ​​the control rats was sparse, while the FIR rats in the graphene electrothermal film group grew dense hair on their abdomens. The difference in the area of ​​new abdominal hair between the two groups was statistically significant ( P <0.05). The results show that the graphene electrothermal film prepared by this method can promote hair growth.

[0090] To further evaluate whether the far infrared intensity of the graphene electric heating film prepared by this method causes skin damage, the abdominal skin of the graphene electric heating film group after FIR radiation for one week was compared with the skin of normal rats. The results are shown in the attached figure. Figure 9 As shown, there is no significant difference in the skin tissue structure of rats in the graphene electric heating film group after FIR radiation and that of normal rats, and the accessory structures such as hair follicles are normal, indicating that the radiation intensity generated by the graphene electric heating film prepared by this method has good biocompatibility.

[0091] In summary, the graphene electric heating film prepared by the present invention has good flexibility, high electric-thermal radiation conversion efficiency, narrow far-infrared radiation wavelength range, and high biological safety. It has good biological application prospects in promoting wound recovery, preventing abdominal adhesions, and promoting hair growth.

[0092] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0093] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A graphene electric heating film, characterized in that: The invention comprises an electrothermal composite material layer and a fiber membrane layer bonded to the upper and lower surfaces of the electrothermal composite material layer, wherein the electrothermal composite material layer is obtained by solidifying a uniform slurry consisting of a graphene composite suspension, a composite resin suspension, a silane coupling agent and vitamin C; wherein, The graphene composite suspension comprises, by weight, 20 to 40 parts of a graphene nanosheet suspension, 20 to 40 parts of conductive carbon black, 2 to 4 parts of ammonium polyacrylate, 2 to 4 parts of sodium dodecylbenzenesulfonate, and 2 to 4 parts of silicone oil, wherein the solid content of the graphene nanosheet suspension is 17 to 22%; The composite resin suspension comprises, by weight, 100 to 200 parts of flame-retardant epoxy resin, 20 to 40 parts of curing agent, 1.5 to 3 parts of leveling agent, 1 to 2 parts of dispersant and 1 to 2 parts of organosilicon defoaming agent.

2. The graphene electric heating film according to claim 1, characterized in that: The weight ratio of the graphene composite suspension to the composite resin suspension, the silane coupling agent and the vitamin C is 1:1:0.01:0.06-0.

1.

3. The graphene electric heating film according to claim 1, characterized in that: The graphene in the graphene nanosheet suspension is a few-layer graphene with 3 to 10 layers and a particle size of 5 to 20 μm, and the particle size of the carbon black is 5 to 30 nm.

4. The graphene electric heating film according to claim 1, characterized in that: The thickness of the graphene electric heating film is 50-300 μm.

5. The graphene electric heating film according to claim 1, characterized in that: The flame retardant epoxy resin is an N-containing flame retardant epoxy resin and / or a P-containing flame retardant epoxy resin.

6. The graphene electric heating film according to claim 1, characterized in that: The fiber membrane layer is a polyester fiber membrane.

7. A method for preparing the graphene electric heating film according to any one of claims 1 to 5, characterized in that: The following operations are included: (1) Preparation of graphene composite suspension: 20-40 parts of graphene nanosheet suspension, 20-40 parts of conductive carbon black, 2-4 parts of ammonium polyacrylate, 2-4 parts of sodium dodecylbenzenesulfonate and 2-4 parts of silicone oil were added to 200 parts of water in sequence, mixed and filtered to remove 90% of the water by volume; (2) Preparation of composite resin suspension: Mix 100-200 parts of flame retardant epoxy resin, 20-40 parts of curing agent, 1.5-3 parts of leveling agent, 1-2 parts of dispersant and 1-2 parts of silicone defoamer, and adjust the pH to 8.0-8.5; (3) The graphene composite suspension and the composite resin suspension are mixed and a silane coupling agent and vitamin C are added, the mixture is stirred and ground, and the resulting slurry is coated between two layers of fiber membranes and cured.

8. The method for preparing a graphene electric heating film according to claim 7, characterized in that: The mixing method in step (1) is: stirring and mixing at a speed of 12000-15000 rpm for 0.5-0.8h.

9. The method for preparing a graphene electric heating film according to claim 7, characterized in that: The stirring speed in step (3) is 12000-15000 rpm, and the stirring time is 1-1.2 h.

10. Use of the graphene electric heating film according to any one of claims 1 to 6 in the preparation of a medical device for promoting wound repair and / or preventing abdominal adhesions and / or promoting hair growth.

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