Preparation method and application of pure carbon self-supporting conductive film

Abstract

The invention relates to the technical field of conductive thin film materials, in particular to a preparation method and application of a pure-carbon-series self-supporting conductive thin film. Comprising the following steps: S1, uniformly stirring and mixing multi-walled carbon nanotube slurry, single-walled carbon nanotube slurry and graphene slurry, adding a film-forming agent oily solution, and uniformly mixing to obtain a coating material; s2, coating a substrate with the coating material in the S1, and then drying and stripping to obtain the pure-carbon-series self-supporting conductive thin film, the sheet resistance of the pure carbon system can reach 4.2 omega / square, and the sheet resistance of a thin film prepared in a general laboratory is less than 20 omega / square and is superior to that of an existing pure carbon film (generally gt and 20 omega / square), and the pure carbon film can be driven under the low voltage of 5V. Due to the characteristic, the deicing device is particularly suitable for the fields of flexible wearable equipment, consumer electronics, deicing in special environments and the like.

Description

Technical Field

[0001] This application relates to the field of conductive thin film materials technology, and in particular to a method for preparing and applying a pure carbon-based self-supporting conductive thin film. Background Technology

[0002] The existing methods for preparing carbon-based conductive films have the following problems: (1) Metal fillers (such as silver-coated copper powder) need to be added to achieve complete peeling from the substrate, which is costly and poses a risk of metal contamination; (2) Pretreatment of the substrate is required, such as plasma, corona or chemical coating, which is complex and requires a large investment in equipment; (3) The sheet resistance of the prepared film is high (usually >20Ω / □), and the low voltage driving performance is insufficient, which makes it difficult to meet the high conductivity requirements of portable electronic devices; (4) Existing technologies are mostly limited to precision coating equipment or CVD method, which has low process tolerance and is difficult to be compatible with simple coating methods such as manual operation. Summary of the Invention

[0003] In order to solve the above-mentioned technical problems, the purpose of this application is to provide a method for preparing a pure carbon-based self-supporting conductive film and its application.

[0004] On one hand, the present invention provides a method for preparing a pure carbon-based self-supporting conductive thin film, comprising the following steps: S1. Mix the multi-walled carbon nanotube slurry, single-walled carbon nanotube slurry and graphene slurry evenly, then add the film-forming agent oily solution and mix evenly to obtain the coating material. S2. Coat the substrate with the coating material from S1, then dry and peel it off to obtain a pure carbon-based self-supporting conductive film.

[0005] In some embodiments, in S1, the proportion of multi-walled carbon nanotube slurry is 20-85 wt%, the proportion of single-walled carbon nanotube slurry is 0-10 wt%, the proportion of graphene slurry is 0-70 wt%, and the proportion of film-forming agent oil solution is 5-30 wt%.

[0006] In some embodiments, in S1, the solid content of the multi-walled carbon nanotube slurry is 2-5%, the solid content of the single-walled carbon nanotube slurry is 0.5-1.2%, the solid content of the graphene slurry is 2-9%, and the solid content of the film-forming agent oil solution is 15-40%. The film-forming agent oil solution includes at least one of polyurethane, PI, PVA, PE, epoxy resin, and phenolic resin oil solutions.

[0007] In some embodiments, in S1, the multi-walled carbon nanotubes in the multi-walled carbon nanotube slurry have an outer diameter of 5-80 nm, a length of 3-100 μm, and a specific surface area of ​​50-330 m². 2The resistivity is less than 900 nΩ·m. The single-walled carbon nanotubes in the slurry have an outer diameter of 0.75-3 nm and a length of 1-50 μm. The graphene in the slurry has a particle size of less than 50 μm and a specific surface area greater than 150 m². 2 / g.

[0008] In some embodiments, in S1, the stirring is performed at 2000 rpm for 20 min.

[0009] In some embodiments, in S2, the substrate comprises a release / non-release PET film or silicone paper.

[0010] In some embodiments, in S2, the coating thickness is 0.02-0.1 mm.

[0011] In some embodiments, in S2, the coating speed is 10-30 mm / s.

[0012] In some embodiments, in S2, the drying temperature is 60-105°C and the drying time is 1-3 hours.

[0013] On the other hand, the present invention also provides an application of the pure carbon-based self-supporting conductive thin film prepared by the above-described preparation method in electronic devices.

[0014] (1) Difference in material system: Existing technologies (such as Aerospace Paimon 2024) require the addition of a large amount of silver-coated copper powder to achieve exfoliation. This invention uses a pure carbon system (multi-wall tube + graphene composite), with zero metal addition, lower cost and no risk of metal pollution; (2) Difference in substrate treatment: Existing technologies usually require plasma, corona or chemical coating treatment of the substrate. This invention does not require any substrate pretreatment and can be directly coated on commercial release film / silicone paper or even ordinary PET film. (3) Difference in peeling method: Existing technologies mostly rely on metal fillers or transfer layers to assist peeling, while this invention achieves direct mechanical peeling through formula optimization, which is done in one step; (4) Difference in process compatibility: Existing technologies are mostly limited to precision laboratory equipment. This invention is compatible with automatic coating machines and manual coating, has high process tolerance, and is easy to promote; (5) Performance advantages: The sheet resistance of the pure carbon system of this invention can reach 4.2Ω / □, which is superior to existing pure carbon films (usually >20Ω / □), and can be driven at a low voltage of 5V. This characteristic makes it particularly suitable for flexible wearable devices (such as smart heated clothing, medical physiotherapy protective gear), consumer electronics products (such as mobile phone battery insulation shells, touch gloves), and de-icing in special environments. The above performance can bring the following direct results: Improved heating uniformity and energy efficiency: Low sheet resistance means that the conductive network of the film layer is excellent, and higher power density and more uniform heating surface can be obtained at the same voltage, resulting in high thermal conversion efficiency. Power supply compatibility and portability: The 5V driving voltage is directly compatible with common USB power supplies or small lithium batteries, without the need for additional boost circuits, simplifying product power supply design, reducing system power consumption and size, and enhancing the portability and safety of the device. Process and cost advantages: Combined with its good process compatibility, this material is easy to integrate into the mass production or flexible product manufacturing, which helps to promote high-performance, low-cost end-application products.

[0015] Meanwhile: (1) Metal-free preparation of pure carbon conductive film was achieved, eliminating the risk of metal pollution and reducing material costs; (2) Direct coating and peeling without substrate pretreatment were achieved, simplifying the process and reducing equipment investment; (3) The prepared film has good flexibility (foldable, thickness 0.03mm), excellent conductivity (sheet resistance 4.2Ω / □), and strong low voltage driving performance (5V to 74℃); (4) High process tolerance, compatible with automatic coating and manual coating, and easy to promote application under different equipment conditions; (5) Excellent far-infrared radiation performance: The film of this invention has a high far-infrared emissivity at room temperature, and the emissivity in the 8-14μm human body radiation band reaches 70-82%, which can effectively radiate far-infrared waves and is suitable for physiotherapy, health care, human body warmth and other fields. Attached Figure Description

[0016] Figure 1 This is a photograph of the coating machine used in Example 1. Figure 2 This is a thickness diagram of the self-supporting conductive film tested in Example 2; Figure 3 This is a direct mechanical peeling diagram of the self-supporting conductive film obtained in Example 1; Figure 4 SEM image of the self-supporting conductive film obtained in Example 1; Figure 5 This is a thickness diagram of the self-supporting conductive film tested in Example 1; Figure 6 The graph shows the thermal performance test results of the self-supporting conductive film obtained in Example 1. Figure 7 The temperature resistance test results of the self-supporting conductive film obtained in Example 1 are shown below. Figure 8The image shows the ultra-low power test results of the self-supporting conductive film obtained in Example 1. Figure 9 This is a direct mechanical peeling diagram of the self-supporting conductive film obtained in Example 2; Figure 10 The diagram shows the bending sheet resistance of the self-supporting conductive film obtained in Example 5. Figure 11 The bending sheet resistance test diagram of the self-supporting conductive film obtained in Example 1 is shown. Figure 12 XRF testing and analysis of the self-supporting conductive film obtained in Example 1; Figure 13 The image shows the thermal performance test results of the self-supporting conductive film obtained in Example 7. Detailed Implementation

[0017] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure. Example 1

[0018] (1) Preparation of multi-walled carbon nanotube slurry: PVP K30 dispersant and NMP solvent were added to multi-walled carbon nanotubes to prepare a multi-walled carbon nanotube slurry with a carbon content of 2% and a solid content of 2.8%. (2) Preparation of single-walled carbon nanotube slurry: PVP K30 dispersant and NMP solvent were added to single-walled carbon nanotubes to prepare a single-walled carbon nanotube slurry with a carbon content of 0.3% and a solid content of 0.7%. (3) Preparation of graphene slurry: PVP K30 dispersant and NMP solvent were added to graphene to prepare a graphene slurry with a carbon content of 4% and a solid content of 6%. (4) Preparation of polyurethane NMP solution: Polyurethane was added to NMP solvent to prepare a polyurethane NMP solution with a solid content of 20%; then, 10g of the above multi-walled carbon nanotube slurry, 1g of single-walled carbon nanotube slurry, and 2g of graphene slurry were taken, mixed, and stirred at 2000rpm for 20 minutes using a high-speed disperser; 1.5g of polyurethane NMP solution was added, and stirring was continued until homogeneous; the outer diameter of the multi-walled carbon nanotubes in the multi-walled carbon nanotube slurry was 5-80nm, the length was 3-100μm, and the specific surface area was 50-330m². 2 / g, resistivity less than 900 nΩ·m, the outer diameter of the single-walled carbon nanotubes in the single-walled carbon nanotube slurry is 0.75-3 nm, the length is 1-50 μm, and the particle size of the graphene in the graphene slurry is less than 50 μm, with a specific surface area greater than 150 m². 2 / g; (5) Coating: Using untreated silicone paper as a substrate, such as... Figure 1 The coating machine shown is an automatic coating machine with a blade gap of 1000μm and a coating speed of 20mm / s. (6) Drying: Dry at 105℃ for 3 hours; (7) Peeling: After complete drying, gently lift the film edge with a blade, such as... Figure 3 , Figure 4 As shown, the self-supporting conductive film can be directly and completely peeled off, with no adhesive residue at the peeling interface and no tearing of the film. (8) Performance: such as Figure 5 The film thickness, measured using a contact thickness gauge (according to GB / T 6672), is 0.039 mm; the sheet resistance, measured using a four-probe tester (according to GB / T 1551), is 4.2 Ω / □. Figure 8 As shown, under a 5V DC voltage, the surface temperature of the material can rise from room temperature to 74°C (test environment: 25°C still air; temperature acquisition: thermocouple or infrared thermal imager); after the voltage is removed, its temperature can return to room temperature within 10 seconds.

[0019] like Figure 6 The membrane obtained in Example 1 was subjected to thermal performance testing, and the following results were obtained: Conclusion 1: Extremely rapid heating / cooling rate (high thermal diffusivity) 8.349 mm 2 The thermal diffusivity of / s is exceptionally high for polymer-based carbon materials. This means that when heated by electricity, heat can be conducted and diffused within the film at an extremely high rate, resulting in a rapid and uniform rise in film surface temperature. Similarly, the heat dissipates quickly after the power is turned off. This directly verifies the excellent performance of "heating to 120℃ in 20 seconds under 22V voltage" in the experiment.

[0020] Conclusion 2: Highly efficient heat transfer capability (high thermal conductivity) The thermal conductivity of 4.6 W / (m·K) is much higher than that of ordinary polymer materials (typically <0.5 W / (m·K)), proving that the three-dimensional conductive network of carbon nanotubes constructed in this invention also forms a highly efficient thermally conductive framework. This allows the carbon film to rapidly conduct the heat converted from electrothermal energy from the heat source (near the electrode) to the entire film surface during operation, eliminating local hot spots and ensuring uniform surface heating.

[0021] Conclusion 3: Extremely low thermal energy storage requirements (low specific heat capacity) A specific heat capacity of 0.709 J / (g·K) means that very little energy is required to heat the carbon film itself to the target temperature. The vast majority of electrical energy is efficiently converted into heat and radiated / conducted outwards, rather than wasted on heating the film itself. This directly brings two benefits: High electrothermal conversion efficiency: Lower energy consumption, which is especially important for scenarios using portable power sources such as power banks.

[0022] Excellent tactile safety: After power is cut off, the membrane itself will not remain at a high temperature for a long time like a "hot stone". It can quickly cool down to room temperature within 10-20 seconds, making it safer to use.

[0023] like Figure 7 As shown, the membrane obtained in Example 1 underwent a temperature resistance test. Its infrared thermography at 12V reached a maximum temperature of 250°C without deformation. The membrane's inertia at 250°C indicates it can withstand the working conditions of most industrial heating scenarios, demonstrating high practical value. This is a crucial safety guarantee for applications such as automotive heating and industrial thermal management. Figure 11 The sheet resistance test of the membrane shown indicates that the sheet resistance remains essentially unchanged after multiple folds. Figure 12 The far-infrared emissivity shown is over 70% in the 8-14μm band at 25℃. Example 2

[0024] (1) Multi-walled carbon nanotubes were added to PVP K30 dispersant and NMP solvent to prepare a multi-walled carbon nanotube slurry with a solid content of 2.8% and a carbon content of 2%. (2) Add polyurethane to NMP solvent to prepare a polyurethane NMP solution with a solid content of 20%.

[0025] (3) Take 13g of the multi-walled carbon nanotube slurry and 3g of polyurethane NMP solution from (2), put them into a stirring cup, and obtain a mixed slurry; (4) Use a vacuum high-speed mixer to quickly mix the slurry from (3), adjusting the speed to 2000 rpm and the time to 20 min; (5) Take a 150mm×200mm silicone paper as a base and place it on the coating machine, then take the slurry from (4) onto the silicone paper; (6) Adjust the doctor blade gap to 1000μm and the coating speed to 20mm / s to coat the film; (7) After coating, place the film from (6) in an oven to dry at 105°C for 3 hours; (8) such as Figure 9 After drying, the film can be peeled off the silicone paper. The film is foldable and flexible. The sheet resistance of the film, measured using a four-probe tester, is 16.1 Ω / □. Figure 2 The film thickness, as shown, was measured to be 0.042 mm using a thickness tester. (9) After adding copper electrodes and PI film to both ends of the film peeled off in (8) for heat preservation, a 22V DC voltage is used for heating test. Within 23s, the film temperature can rise from room temperature to 120℃. After disconnecting the power supply, the film temperature can return to room temperature within 20s. Example 3

[0026] Same as Example 2, except that: 4g of polyurethane NMP solution, with a non-release PET film as the substrate; The final sheet resistance of the thin film was 26.3 Ω / □, and the thickness was 0.038 mm. The thin film was heated from room temperature to 100 °C within 20 seconds under a DC voltage of 22 V. Example 4

[0027] Same as Example 1, except that: 14g of multi-walled carbon nanotube slurry, 1g of single-walled carbon nanotube slurry, 1g of graphene slurry, and 1.5g of polyurethane NMP solution were mixed to obtain a film with a sheet resistance of 4.2Ω / □ and a thickness of 0.035mm. (7) and (4) show that the film temperature rises from 29°C to 110°C within 9 seconds under a 22V DC voltage; and from room temperature to 74°C within 30 seconds under a 5V DC voltage. Example 5

[0028] Same as Example 1, except that: 16g of multi-walled carbon nanotube slurry, 1g of graphene slurry, 1.5g of polyurethane NMP solution; the film sheet resistance is 16.2Ω / □, and the thickness is 0.035mm; the film temperature rises from 25℃ to 110℃ within 9 seconds under 22V DC voltage; under 5V DC voltage... Figure 10 The sheet resistance test of the membrane shown in the figure shows that the sheet resistance remains unchanged after multiple folds because the carbon nanotubes play a role in building the network. Example 6

[0029] Same as Example 1, except that: 17g of multi-walled carbon nanotube slurry, 4.5g of polyurethane NMP solution, thin film sheet resistance of 30.2Ω / □, thickness of 0.052mm; the film temperature rises from 25℃ to 110℃ within 40s under 22V DC voltage. Example 7

[0030] Same as Example 1, except that: 16g of multi-walled carbon nanotube slurry, 1g of graphene slurry, and 2g of polyurethane NMP solution were coated using a doctor blade with a gap of 500μm. The coating was then vacuum-dried at 60℃ for 1 hour, 80℃ for 1 hour, and 105℃ for 2 hours. The film had a sheet resistance of 21Ω / □ and a thickness of 0.029mm. The film's temperature increased from 22.3℃ to 95.8℃ within 8 seconds under a 12V DC voltage. Figure 13 .

[0031] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a pure carbon-based self-supporting conductive thin film, characterized in that, Includes the following steps: S1. Mix the multi-walled carbon nanotube slurry, single-walled carbon nanotube slurry and graphene slurry evenly, then add the film-forming agent oily solution and mix evenly to obtain the coating material. S2. Coat the substrate with the coating material from S1, then dry and peel it off to obtain a pure carbon-based self-supporting conductive film.

2. The preparation method according to claim 1, characterized in that, In S1, the proportion of multi-walled carbon nanotube slurry is 20-85 wt%, the proportion of single-walled carbon nanotube slurry is 0-10 wt%, the proportion of graphene slurry is 0-70 wt%, and the proportion of film-forming agent oil solution is 5-30 wt%.

3. The preparation method according to claim 1, characterized in that, In S1, the solid content of the multi-walled carbon nanotube slurry is 2-5%, the solid content of the single-walled carbon nanotube slurry is 0.5-1.2%, the solid content of the graphene slurry is 2-9%, and the solid content of the film-forming agent oil solution is 15-40%. The film-forming agent oil solution includes at least one of polyurethane, PI, PVA, PE, epoxy resin, and phenolic resin oil solutions.

4. The preparation method according to claim 1, characterized in that, In S1, the multi-walled carbon nanotubes in the slurry have an outer diameter of 5-80 nm, a length of 3-100 μm, and a specific surface area of ​​50-330 m². 2 The resistivity is less than 900 nΩ·m. The single-walled carbon nanotubes in the slurry have an outer diameter of 0.75-3 nm and a length of 1-50 μm. The graphene in the slurry has a particle size of less than 50 μm and a specific surface area greater than 150 m². 2 / g.

5. The preparation method according to claim 1, characterized in that, In S1, the stirring is performed at 2000 rpm for 20 min.

6. The preparation method according to claim 1, characterized in that, In S2, the substrate comprises a release / non-release PET film or silicone paper.

7. The preparation method according to claim 1, characterized in that, In S2, the coating thickness is 0.02-0.1 mm.

8. The preparation method according to claim 1, characterized in that, In S2, the coating speed is 10-30 mm / s.

9. The preparation method according to claim 1, characterized in that, In S2, the drying temperature is 60-105℃ and the drying time is 1-3h.

10. The application of a pure carbon-based self-supporting conductive thin film prepared by any one of claims 1-9 in electronic devices.

Images