A heating film capable of emitting plane electromagnetic waves and a method for manufacturing the same

Abstract

The application relates to the technical field of heating films, and discloses a heating film capable of emitting planar electromagnetic waves and a preparation method thereof, which comprises the following steps: S1) adding water and a dispersing agent into nano carbon fibers which are ground for 30-100 hours, and uniformly mixing to prepare carbon fiber slurry; S2) mixing and uniformly dispersing arnos short fibers and arnos pulp to prepare arnos slurry; S3) mixing the carbon fiber slurry and the arnos slurry, and uniformly dispersing to prepare carbon fiber-arnos mixed slurry; S4) adopting papermaking equipment to press the carbon fiber-arnos mixed slurry into a film semi-product; and S5) adopting a double-roller hot press to hot-press form the film semi-product under the condition of 200-400 DEG C and 20-200 MPa, so that the heating film is prepared; and the wavelength of the planar electromagnetic waves emitted by the prepared heating film after electrification is 2-20 microns. The process is simple, the equipment is simple, and the manufacturing cost is low.

Description

Technical Field

[0001] This invention relates to the field of heating film technology, and in particular to a heating film capable of emitting planar electromagnetic waves and its preparation method. Background Technology

[0002] Existing electrothermal heating elements include heating materials such as graphene heating elements, metal resistance wires, and / or PTC. These traditional heating elements need to raise their own temperature after being energized before they can transfer heat to the outside through thermal radiation, convection, and / or conduction. Due to the thermal resistance formed by the air around the heating element, the electrothermal conversion efficiency of these heating materials is low.

[0003] The manufacturing processes of PTC and graphene heating elements are complex and require specialized production equipment, resulting in high manufacturing costs.

[0004] Metal resistance wires are prone to wear and tear after being heated by electricity, resulting in a short service life. Summary of the Invention

[0005] To address the aforementioned problems, the primary objective of this invention is to provide a method for preparing a heating film that features a simple manufacturing process, low manufacturing cost, and the ability to emit planar electromagnetic waves with high electrothermal conversion efficiency.

[0006] The second objective of this invention is to provide a heating film prepared by the above method, wherein the heating film can emit planar electromagnetic waves, has no loss during the heating process, and has a long service life.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A method for preparing a heating film includes the following steps;

[0009] S1) Add water and dispersant to the nanofibers that have been ground for 30-100 hours, mix thoroughly, and obtain a carbon fiber slurry:

[0010] S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp;

[0011] S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry;

[0012] S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment;

[0013] S5) Using a double-roll hot press, the semi-finished film is hot-pressed into shape at 200-400℃ and 20-200MPa to obtain the heating film.

[0014] The wavelength of the plane electromagnetic wave emitted by the prepared heating film after being energized is 2-20 μm.

[0015] Specifically, in step S1), the carbon fiber slurry comprises 5-60 wt% nano-carbon fiber, 0.5-3 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride.

[0016] Preferably, in step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:1.

[0017] Preferably, in step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 10-80 wt%.

[0018] Preferably, in step S4), the thickness of the semi-finished film is 0.03-0.04 mm;

[0019] In step S5), the thickness of the heating film is 0.055-0.065 mm.

[0020] Furthermore, the present invention proposes a heating thin film capable of emitting planar electromagnetic waves, which is prepared using the heating thin film preparation method described above;

[0021] The operating temperature of the heating film, which can emit planar electromagnetic waves after being powered on, is 230-400℃.

[0022] Furthermore, the thermal shrinkage rate of the heating film after being energized is 0.5-1%.

[0023] Preferably, the weight per unit area of ​​the heating film is 60-80 g / m². 2 .

[0024] The beneficial effects of the above-mentioned technical solution of the present invention are as follows: the method for preparing the heating film involves hot pressing to cross-overlap and bond the aramid short fibers and aramid fibers in the aramid pulp into one piece. The nanofibers in the carbon fiber pulp fill the pores between the aramid short fibers and the aramid fibers. The heating film, when energized, can emit plane electromagnetic waves with a wavelength of 2-20μm to the surrounding environment, thereby heating the surrounding objects. It does not require heat transfer through convection and conduction. Compared with the existing resistance heating element, it has good electrothermal conversion efficiency, simple preparation process, simple equipment, and low manufacturing cost.

[0025] Furthermore, the heating film capable of emitting planar electromagnetic waves proposed in this invention can operate and generate heat at 230-400℃ after being energized, exhibiting excellent heat resistance and a thermal shrinkage rate as low as 0.5-1%. Attached Figure Description

[0026] Figure 1 This is a waveform test result diagram of the heating thin film capable of emitting planar electromagnetic waves according to Embodiment 3 of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0028] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0030] A method for preparing a heating film includes the following steps;

[0031] S1) Add water and dispersant to the nanofibers that have been ground for 30-100 hours, mix thoroughly, and obtain a carbon fiber slurry:

[0032] S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp;

[0033] S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry;

[0034] S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment;

[0035] S5) Using a double-roll hot press, the semi-finished film is hot-pressed into shape at 200-400℃ and 20-200MPa to obtain the heating film.

[0036] The wavelength of the plane electromagnetic wave emitted by the prepared heating film after being energized is 2-20 μm.

[0037] The method for preparing the heating film of the present invention involves hot pressing to cross-overlap and bond aramid short fibers and aramid fibers in aramid pulp into one piece. Nanofibers in carbon fiber pulp fill the pores between aramid short fibers and aramid fibers. The preparation process is simple, requires simple equipment, and has the advantages of low manufacturing cost.

[0038] The heating temperature of the heating film can be adjusted by controlling the input current. When powered on, the heating film emits plane electromagnetic waves with wavelengths of 2-20μm, which heats the surrounding objects. After power is cut off, the heating film can cool down to room temperature within 30 seconds. The heating film does not need to transfer heat through convection and conduction. Compared with the existing resistive heating elements, it has good electrothermal conversion efficiency. Furthermore, the heating film has no loss during the heating process and has the advantage of long service life.

[0039] Specifically, in step S1), the carbon fiber slurry comprises 5-60 wt% nano-carbon fiber, 0.5-3 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride.

[0040] The uniformity of carbon nanofiber dispersion in water is improved by using polyvinylidene fluoride as a dispersant, and carbon fiber slurry is formed.

[0041] Preferably, in step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:1.

[0042] The heating film, pressed from aramid fibers and aramid pulp in a weight ratio of 1:1, has a porosity of 40-60%, which is beneficial for the filling of the pores between the aramid short fibers and aramid fibers by the carbon nanofibers.

[0043] Preferably, in step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 10-80 wt%.

[0044] By controlling the content of carbon nanofibers in the fiber-aramid mixed slurry, the sheet resistance of the prepared heating film can be controlled to ensure the stability of the heating film's heating performance.

[0045] Preferably, in step S4), the thickness of the semi-finished film is 0.03-0.04 mm;

[0046] In step S5), the thickness of the heating film is 0.055-0.065 mm.

[0047] While ensuring the tensile strength and electrical properties of the heating film, the thickness of the semi-finished film is controlled to be approximately 35 μm, and the thickness of the heating film is controlled to be approximately 60 μm.

[0048] Furthermore, the present invention proposes a heating thin film capable of emitting planar electromagnetic waves, which is prepared using the heating thin film preparation method described above;

[0049] The operating temperature of the heating film, which can emit planar electromagnetic waves after being powered on, is 230-400℃.

[0050] The heating film can adapt to high-temperature working environments of 230-400℃ and has good heat resistance.

[0051] Furthermore, the thermal shrinkage rate of the heating film after being energized is 0.5-1%.

[0052] The heating temperature and related thermal shrinkage rate data of carbon crystal, graphene and carbon fiber are shown in Table 1 below. By comparing the relevant data, it can be found that the heating temperature of carbon crystal, graphene and carbon fiber is lower than the working temperature of the heating film of the present invention, and the thermal shrinkage rate is higher than that of the heating film of the present invention, which is 0.5-1%.

[0053] Table 1. Heating temperatures and corresponding thermal shrinkage rates of carbon crystal, graphene, and carbon fiber.

[0054] Heating material Heating temperature (°C) Thermal shrinkage rate (%) at the corresponding temperature carbon crystal 60-80 2.5-4.5％ graphene 80-120 1.3-1.8％ carbon fiber 80-150 0.7-1.5％

[0055] Preferably, the weight per unit area of ​​the heating film is 60-80 g / m². 2 .

[0056] The heating film has the advantage of being lightweight. If the heating film is used as the heating material, the weight increase of the original equipment after assembling the heating film is very small.

[0057] Examples 1-3

[0058] The heating thin film capable of emitting planar electromagnetic waves of Example 1 was prepared according to the following steps:

[0059] S1) Water and dispersant are added to the nanofibers that have been ground for 60 hours and mixed evenly to obtain a carbon fiber slurry:

[0060] S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp;

[0061] S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry;

[0062] S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment;

[0063] S5) Using a double-roll hot press, the semi-finished film is hot-pressed at 250°C and 120MPa to obtain the heating film.

[0064] In step S1), the carbon fiber slurry comprises 40 wt% nano-carbon fiber, 1 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride;

[0065] In step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:1.

[0066] In step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 40 wt%.

[0067] In step S4), the thickness of the semi-finished film is 0.03-0.04 mm;

[0068] In step S5), the thickness of the heating film is 0.055-0.065 mm.

[0069] Example 2

[0070] The heating thin film capable of emitting planar electromagnetic waves of Example 2 was prepared according to the following steps:

[0071] S1) Water and dispersant were added to the nanofibers that had been ground for 85 hours and mixed evenly to obtain a carbon fiber slurry:

[0072] S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp;

[0073] S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry;

[0074] S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment;

[0075] S5) Using a double-roll hot press, the semi-finished film is hot-pressed at 320℃ and 160MPa to obtain the heating film.

[0076] In step S1), the carbon fiber slurry comprises 50 wt% carbon nanofibers, 1.5 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride;

[0077] In step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:1.

[0078] In step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 60 wt%.

[0079] In step S4), the thickness of the semi-finished film is 0.03-0.04 mm;

[0080] In step S5), the thickness of the heating film is 0.055-0.065 mm.

[0081] Example 3

[0082] The heating thin film capable of emitting planar electromagnetic waves of Example 3 was prepared according to the following steps:

[0083] S1) Water and dispersant are added to the nanofibers that have been ground for 95 hours and mixed evenly to obtain a carbon fiber slurry:

[0084] S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp;

[0085] S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry;

[0086] S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment;

[0087] S5) Using a double-roll hot press, the semi-finished film is hot-pressed at 380℃ and 190MPa to obtain the heating film.

[0088] In step S1), the carbon fiber slurry comprises 55 wt% nano-carbon fiber, 2 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride;

[0089] In step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:1.

[0090] In step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 75 wt%.

[0091] In step S4), the thickness of the semi-finished film is 0.03-0.04 mm;

[0092] In step S5), the thickness of the heating film is 0.055-0.065 mm.

[0093] Performance testing

[0094] The density, fracture strength, elongation at break, curl, moisture regain, thermal shrinkage, and limiting oxygen index of the heating films capable of emitting planar electromagnetic waves in Examples 1-3 were tested, and the operating temperature of the heating films capable of emitting planar electromagnetic waves when energized was recorded.

[0095] Table 2 shows the performance test results of the heating films capable of emitting planar electromagnetic waves in Examples 1-3.

[0096] Performance items Example 1 Example 2 Example 3 <![CDATA[Density (g / m 2 )]]> 50 55 60 Fracture strength (cN / dtex) ≥3.0 ≥3.2 ≥3.5 Elongation at break (%) 20 20 20 Curl (°) ≥9 ≥9 ≥9 Moisture regain (%) 6.28 6.28 6.28 Heat shrinkage rate (%) ≤0.5％ ≤0.5％ ≤0.5％ Limiting oxygen index (%) 33％ 33％ 33％

[0097] In summary, the method for preparing the heating film involves hot pressing to cross-overlap and bond aramid short fibers and aramid fibers in aramid pulp into a single unit. Nanofibers in carbon fiber pulp fill the pores between the aramid short fibers and aramid fibers. When energized, the heating film can emit planar electromagnetic waves with wavelengths of 2-20 μm to heat surrounding objects without the need for heat transfer through convection and conduction. Compared with existing resistance heating elements, it has good electrothermal conversion efficiency, a simple preparation process, simple equipment requirements, and low manufacturing cost.

[0098] Furthermore, the heating film capable of emitting planar electromagnetic waves proposed in this invention can operate and generate heat at 230-400℃ after being energized, exhibiting excellent heat resistance and a thermal shrinkage rate as low as 0.5-1%.

[0099] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a heating film, characterized in that, Includes the following steps; S1) Add water and dispersant to the nanofibers that have been ground for 30-100 hours, mix thoroughly, and obtain a carbon fiber slurry: S2) Mix and disperse aramid staple fiber and aramid pulp evenly to obtain aramid pulp; S3) Mix the carbon fiber slurry and the aramid fiber slurry, disperse them evenly, and obtain a carbon fiber-aramid fiber mixed slurry; S4) The carbon fiber-aramid mixed slurry is pressed into a film semi-finished product using papermaking equipment; S5) Using a double-roll hot press, the semi-finished film is hot-pressed into shape at 200-400℃ and 20-200MPa to obtain the heating film. The wavelength of the plane electromagnetic wave emitted by the prepared heating film after being energized is 2-20 μm.

2. The method for preparing the heating film according to claim 1, characterized in that, In step S1), the carbon fiber slurry comprises 5-60 wt% nano-carbon fiber, 0.5-3 wt% dispersant and the balance being water, wherein the dispersant is polyvinylidene fluoride.

3. The method for preparing the heating film according to claim 1, characterized in that, In step S2), the fiber length of the aramid staple fiber is 4-12 mm; the mixing weight ratio of the aramid staple fiber and the aramid pulp is 1:

1.

4. The method for preparing the heating film according to claim 1, characterized in that, In step S3), the content of nano-carbon fiber in the carbon fiber-aramid mixed slurry is 10-80 wt%.

5. The method for preparing the heating film according to claim 1, characterized in that, In step S4), the thickness of the semi-finished film is 0.03-0.04 mm; In step S5), the thickness of the heating film is 0.055-0.065 mm.

6. A heating thin film capable of emitting planar electromagnetic waves, characterized in that, It is prepared using the method for preparing the heating film according to any one of claims 1-5; The operating temperature of the heating film, which can emit planar electromagnetic waves after being powered on, is 230-400℃.

7. The heating thin film capable of emitting planar electromagnetic waves according to claim 6, characterized in that, The thermal shrinkage rate of the heating film after being energized is 0.5-1%.

8. The heating thin film capable of emitting planar electromagnetic waves according to claim 6, characterized in that, The heating film has a unit area weight of 60-80 g / m². 2 .

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