Preparation Method and Application of a Large-Area Flexible Electric Heating Sheet

Abstract

The present invention discloses a preparation method and application of a large-area flexible electric heating sheet. The steps of the preparation method at least include the following steps: (1) preparation of a nano-carbon composite film; (2) film punching; (3) fitting of a flexible conductive electrode; (4) fitting of a heat-conducting film; (5) fitting of a surface flexible substrate. In this application, the flexible electric heating sheet prepared by the composite preparation method of the nano-carbon composite film multi-functional layer film has excellent electric heating performance, and at the same time avoids the defects such as hard texture, obvious foreign body sensation, and poor air permeability of some existing electric heating sheets, and has excellent electric heat generation efficiency, bending resistance, water washing resistance and other properties, and has broad development prospects.

Description

Technical Field

[0001] The present invention relates to the field of H05B3 / 02 in IPC classification, and particularly relates to a preparation method and application of a large-area flexible electric heating sheet. Background Art

[0002] Heat sources play an important role in people's production, life, and scientific research. A surface heat source is a type of heat source. The surface heat source is a two-dimensional structure. The object to be heated is placed above this two-dimensional structure to heat the object. Therefore, the surface heat source can heat each part of the object to be heated simultaneously, with a relatively large heating area, uniform heating, and high efficiency. Surface heat sources have been successfully used in industrial fields, scientific research fields, or life fields, such as electric heaters, electric blankets, infrared therapeutic devices, and electric heaters, etc.

[0003] Existing surface heat sources generally include a heating element and at least two electrodes. The at least two electrodes are disposed on the surface of the heating element and are electrically connected to the heating element. When a voltage or current is applied to the heating element through the electrodes, since the heating element has a relatively large resistance, the electrical energy applied to the heating element is converted into heat energy and released from the heating element. Currently, commercially available surface heat sources usually use electric heating wires made of metal wires or carbon fibers as heating elements for electrothermal conversion. However, some existing surface heat sources are relatively thick and hard in texture, and the ratio of the heat generation area to the product area is extremely small. They are not resistant to bending, which greatly affects the performance of the surface heat source / electric heating sheet. For example, in a graphene paste surface heating system, PET or PI sheets are used as the carrier substrate, and graphene conductive paste is printed on the carrier substrate. It has a sandwich structure with two layers of substrates sandwiching a heating body. However, due to the relatively hard texture of PET or PI sheets, they can only be bent but not folded, kneaded, washed, etc., and have poor flexibility and comfort.

[0004] More specifically, due to the performance limitations of the heating element in the existing technology, it is difficult to effectively expand the heat conduction area of the surface heat source itself, and it does not have strong folding and bending resistance. These all limit the performance quality of the surface heat source product and the corresponding application environments and fields.

[0005] The prior art (CN201911297921.8) provides a preparation method of a carbon material electric heating sheet. Its steps mainly include: attaching a carbon material heating element to the surface of a thermoplastic film and connecting the thermoplastic film to a power source with a wire, and then generating heat. It claims to have the advantages of low energy consumption and high efficiency. However, in actual use, due to its carbon fiber heating element being a single short-cut carbon fiber material, there are certain pores in heat transfer and heat generation density, the texture is not soft enough, the folding and bending resistance is poor, and it is unable to effectively further expand the heat generation area of the electric heating sheet, resulting in low actual use efficiency.

[0006] Therefore, developing a preparation method for a large-area flexible electric heating sheet is a very meaningful thing. In the preparation method of the electric heating sheet in this invention application, the most important thing is that a heat conduction layer structure is formed by the thermal lamination of the nano-carbon composite film and the heat conduction film, which can further spread the heat emitted by the nano-carbon composite film through the heat conduction film with a larger area. While reducing the heat collection phenomenon, it can also greatly expand the heating area of the electric heating sheet, thus solving the industry pain point that the proportion of the heating area in the electric heating sheet industry cannot be effectively expanded. Summary of the Invention

[0007] To solve the above problems, the first aspect of the present invention provides a preparation method for a large-area flexible electric heating sheet, and the steps at least include the following steps: (1) Preparation of the nano-carbon composite film; (2) Drilling holes in the film; (3) Laminating the flexible conductive electrode; (4) Laminating the heat conduction film; (5) Laminating the surface flexible substrate.

[0008] In some preferred embodiments, the preparation of the nano-carbon composite film is as follows: Weigh the raw materials required for the carbon nano-carbon composite film, melt and stir them at high temperature, and then print conductive silver paste on the film surface after casting, rolling, stretching and shaping the composite material, and dry it to obtain the nano-carbon composite film.

[0009] In some preferred embodiments, the drilling of the film is as follows: Circular perforations are added to the surface of the nano-carbon composite film by laser drilling, and the distance between the perforations is 0.2 - 0.5 cm; the diameter of the circular perforation is 0.1 - 0.3 cm.

[0010] In some preferred embodiments, the lamination of the flexible conductive electrode is as follows: A flexible conductive electrode is laminated on the surface of the nano-carbon composite film, and a protective layer made of PET or PI material is combined on the surface of the flexible conductive electrode.

[0011] In some preferred embodiments, the lamination of the heat conduction film is as follows: Another heat conduction film is laminated on the surface of the nano-carbon composite film laminated with the flexible conductive electrode to form a heat conduction layer structure.

[0012] In some preferred embodiments, the lamination of the surface flexible substrate is as follows: Flexible substrates are laminated on the upper and lower surfaces of the heat conduction layer to form a complete electric heating sheet.

[0013] In some preferred embodiments, the raw materials of the nano-carbon composite film at least include multi-dimensional carbon materials and thermoplastic resins.

[0014] In some preferred embodiments, the mass ratio of the multi-dimensional carbon materials to the thermoplastic resins is 5 - 8:2 - 4.

[0015] In some preferred embodiments, the mass ratio of the multi-dimensional carbon materials to the thermoplastic resins is 7:3.

[0016] In some preferred embodiments, the sheet resistance of the nano-carbon composite film is 0.1 to 10 ohms.

[0017] In some preferred embodiments, the thickness of the nano-carbon composite film is 10 to 100 μm.

[0018] In some preferred embodiments, the multi-dimensional carbon material is at least two of nano-carbon powder, carbon-coated nano-metal, carbon nanotubes, carbon nanofibers, graphene, and reduced graphene oxide.

[0019] In some preferred embodiments, the multi-dimensional carbon material is nano-carbon powder, multi-walled carbon nanotubes, and graphene.

[0020] In some preferred embodiments, the mass ratio of the nano-carbon powder, multi-walled carbon nanotubes, and graphene is 2 to 3:4 to 5:2 to 3.

[0021] In some preferred embodiments, the mass ratio of the nano-carbon powder, multi-walled carbon nanotubes, and graphene is 2.5:4.5:2.

[0022] In some preferred embodiments, the fineness of the nano-carbon powder is 50 to 300 nm.

[0023] In some preferred embodiments, the fineness of the nano-carbon powder is 80 nm.

[0024] In some preferred embodiments, the thickness of the graphene is 3 to 4 nm, and the sheet diameter is 6 to 8 μm.

[0025] In some preferred embodiments, the thickness of the graphene is 4 nm, and the sheet diameter is 6 μm.

[0026] In some preferred embodiments, the diameter of the multi-walled carbon nanotubes is 10 to 18 nm, and the length is 60 to 90 μm.

[0027] In some preferred embodiments, the diameter of the multi-walled carbon nanotubes is 15 nm, and the length is 80 μm.

[0028] In some preferred embodiments, the thermoplastic resin is at least one of polyurethane resin, phenolic resin, and epoxy resin with an average viscosity range of 8000 to 26000 cps at 25 °C.

[0029] In some preferred embodiments, the thermoplastic resin is polyurethane resin with an average viscosity of 10000 cps at 25 °C.

[0030] In some preferred embodiments, the specific method for preparing the nano-carbon composite film is as follows: (1) Weigh the required amounts of the multi-dimensional carbon material and the thermoplastic resin, and melt and blend them evenly through a high-speed mixer. The temperature for melt blending and stirring is 140-200 °C; (2) After mixing evenly, the composite material is formed into a uniform composite film through casting, calendering, stretching, and shaping; (3) Print conductive silver paste on the surface of the composite film to prepare a conductive silver paste layer, and then dry it to obtain the product.

[0031] In some preferred embodiments, the sheet resistance of the conductive silver paste is 5-10 mΩ; the thickness of the conductive silver paste layer is 3-5 μm.

[0032] In some preferred embodiments, the method of lamination is hot melt adhesive thermal lamination.

[0033] In some preferred embodiments, the hot melt adhesive is at least one of polyurethane elastic rubber and EVA.

[0034] In some preferred embodiments, the flexible conductive electrode is at least one of conductive wire, conductive metal foil, and conductive cloth.

[0035] In some preferred embodiments, there are 2 flexible conductive electrodes, and the flexible conductive electrodes are electrically connected to the power supply through wires and flexible circuit boards.

[0036] In some preferred embodiments, the heat-conducting film is at least one of heat-conducting silicone grease film, graphene heat-conducting film, heat-conducting gel film, and heat-conducting fabric film.

[0037] In some preferred embodiments, the surface flexible substrate is at least one of fiber fabric, flexible silicone, heat storage material, and reflective material.

[0038] The second aspect of the present invention provides an application of the preparation method of the above-mentioned large-area flexible electric heating sheet, including the application of the preparation method of the flexible electric heating sheet in the preparation of large-area flexible electric heating sheets, water-washable flexible electric heating sheets, and bend-resistant flexible electric heating sheets.

[0039] Advantageous effects:

[0040] 1. In this application, the flexible electric heating sheet prepared by the composite preparation method of the nano-carbon composite film multi-functional layer film has excellent electric heating performance, and at the same time avoids the defects of some existing electric heating sheets, such as hard texture, obvious foreign body sensation, and poor air permeability, and has excellent electric heating efficiency, bend resistance, and water-wash resistance and other properties.

[0041] 2. In this application, a heat spreader formed by laminating a nano-carbon composite film and a heat-conducting film effectively reduces the heat collection effect, enables a faster and more uniform heating rate, and significantly increases the overall heating area of the electric heating sheet, avoiding phenomena such as alternating hot and cold.

[0042] 3. In this application, by performing punching operations such as laser and die-cutting on the heating element and the nano-carbon composite film, while solving the air permeability problem, through the design and transformation of the hole size arrangement, shape, and quantity, etc., the electron transport direction on the carbon material film can be changed, and the resistance, heating temperature, and heating area of the electric heating sheet can be adjusted. This enables products with multiple resistances and multiple heating conditions to be achieved by simply changing the punching arrangement and shape using only the same type of carbon material film during the production and preparation process, which has great economic and practical benefits. Specific Embodiments

[0043] Example 1

[0044] Example 1 provides a method for preparing a flexible electric heating sheet with a certain area. The steps at least include the following: (1) Preparation of the nano-carbon composite film; (2) Punching the film; (3) Laminating the flexible conductive electrode; (4) Laminating the heat-conducting film; (5) Laminating the surface flexible substrate.

[0045] The preparation of the nano-carbon composite film (by weight): (1) Weigh 70 parts of a mixture of nano-carbon powder, multi-walled carbon nanotubes, and graphene and 30 parts of polyurethane resin, and melt and blend them evenly through a high-speed mixer. The melt blending temperature is 180°C; (2) After mixing evenly, the composite material is formed into a uniform composite film through casting, calendering, stretching, and shaping; (3) Print conductive silver paste on the surface of the composite film to prepare a conductive silver paste layer, and dry it to obtain.

[0046] The sheet resistance of the conductive silver paste is 8 mΩ; the thickness of the conductive silver paste layer is 4 μm.

[0047] The thickness of the nano-carbon composite film is 60 μm; the sheet resistance is 8 Ω.

[0048] The mass ratio of nano-carbon powder, multi-walled carbon nanotubes, and graphene is 2.5:4.5:2.

[0049] The average fineness of the nano-carbon powder is 80 nm.

[0050] The thickness of graphene is 4 nm, and the sheet diameter is 6 μm; the diameter of the multi-walled carbon nanotubes is 15 nm, and the length is 80 μm.

[0051] The viscosity of the polyurethane resin is 10000 cps at 25°C.

[0052] The film punching is as follows: circular perforations are added to the surface of the nano-carbon composite film by laser punching, and the distance between the perforations is 0.3 cm; the diameter of the circular perforations is 0.2 cm.

[0053] The flexible conductive electrode attachment is as follows: a flexible conductive electrode is attached to the surface of the nano-carbon composite film, and a protective layer of PET material is combined on the surface of the flexible conductive electrode.

[0054] The flexible conductive electrode consists of two upper and lower conductive cloths, and the flexible conductive electrode is connected to a wire and directly connected to a power source.

[0055] The heat-conducting film attachment is as follows: a heat-conducting film is attached to the surface of the nano-carbon composite film with a flexible conductive electrode attached to form a heat-sinking layer structure.

[0056] The heat-conducting film is a graphene heat-conducting film.

[0057] The surface flexible substrate attachment is as follows: flexible substrates are attached to the upper and lower surfaces of the heat-sinking layer to form a complete electric heating sheet.

[0058] The surface flexible substrate is a polyacrylonitrile fiber fabric.

[0059] The attachment method is hot melt adhesive thermal composite attachment; the hot melt adhesive is a polyurethane elastic rubber.

[0060] In this embodiment, the conductive silver paste is a conductive silver paste product sold by Huizhou Chenghui Technology Co., Ltd.

[0061] In this embodiment, the nano-carbon powder, multi-walled carbon nanotubes, and graphene are nano-carbon powder, multi-walled carbon nanotubes, and graphene products sold by Shanghai Xiaohuang Nano Technology Co., Ltd.

[0062] In this embodiment, the polyurethane resin is a polyurethane resin product sold by Anhui Zhongen Chemical Co., Ltd. with an average viscosity of 10,000 cps at 25 °C.

[0063] In this embodiment, the conductive cloth is a black conductive cloth product sold by Suzhou Bazuan New Material Technology Co., Ltd.

[0064] In this embodiment, the graphene heat-conducting film is a graphene heat-conducting film product sold by Shenzhen Maiji High-Tech Co., Ltd. with a thermal conductivity of 1500 w / mk.

[0065] In this embodiment, the polyacrylonitrile flexible fiber fabric is a polyacrylonitrile flexible fiber fabric product sold by Shenyang Arite Special Engineering Materials Co., Ltd.

[0066] In this embodiment, the polyurethane elastic rubber is a polyurethane elastic rubber product sold by Dongguan Pinsu Polymer Technology Co., Ltd.

[0067] Example 2

[0068] The specific implementation manner of this embodiment is the same as that of Embodiment 1, except that the mass ratio of nano carbon powder, multi-walled carbon nanotubes and graphene is 3:5:2.

[0069] Example 3

[0070] The specific implementation manner of this embodiment is the same as that of Embodiment 1, except that the fineness of the nano carbon powder is 120 nm.

[0071] Comparative Example 1

[0072] The specific implementation manner of this comparative example is the same as that of Embodiment 1, except that the mass ratio of nano carbon powder, multi-walled carbon nanotubes and graphene is 1:5:2.

[0073] Comparative Example 2

[0074] The specific implementation manner of this comparative example is the same as that of Embodiment 1, except that the fineness of the nano carbon powder is 500 nm.

[0075] Performance evaluation

[0076] 1. Sheet resistance: The sheet resistance of the carbon nano composite films prepared in all examples and comparative examples was tested by a sheet resistance tester. Five specimens were tested for each example and comparative example, and the average value of the measured values was recorded in Table 1.

[0077] Flexural folding property: The large-area flexible electric heating sheet materials prepared in all examples and comparative examples were cut into samples with a size of 5 cm x 5 cm, and the folding test of the samples was carried out. Each sample was folded 100 times, and after observing 100 times, whether there were obvious creases and fractures on the surface of the sample was observed, and the observed situation was recorded in Table 1.

[0078] 2. Wash resistance: The large-area flexible electric heating sheet materials prepared in all examples and comparative examples were cut into samples with a size of 20 cm x 20 cm, and the washing test of the samples was carried out. The test method refers to GB / T 13769-2009 and GB / T8629-2017, and the working condition of the heating sheet was observed, and the observed situation was recorded in Table 1.

[0079] Table 1

[0080]

[0081] It can be known from Examples 1 to 3, Comparative Examples 1 to 2 and Table 1 that a preparation method and application of a large-area flexible electric heating sheet provided by the present invention result in a flexible electric heating sheet with excellent texture and soft handfeel, as well as excellent water wash resistance, bending and folding resistance and heating effect. Moreover, the heating area of the electric heating sheet is effectively increased, making it suitable for popularization in the textile field and having broad development prospects. Among them, Example 1 obtained the best performance index under the factors of the best raw material ratio and preparation process, etc.

Claims

1. A preparation method of a large-area flexible electric heating sheet, characterized in that: The steps at least include the following steps: (1) Preparation of the nano-carbon composite film; (2) Punching the film; (3) Attaching the flexible conductive electrode; (4) Attaching the heat-conducting film; (5) Attaching the surface flexible substrate; The raw materials of the nano-carbon composite film include multi-dimensional carbon materials and thermoplastic resins; the mass ratio of the multi-dimensional carbon materials to the thermoplastic resins is 5-8:2-4; the multi-dimensional carbon materials are nano-carbon powder, multi-walled carbon nanotubes and graphene; the mass ratio of the nano-carbon powder, multi-walled carbon nanotubes and graphene is 2-3:4-5:2-3; the fineness of the nano-carbon powder is 50-300 nm; The film punching is: adding circular perforations on the surface of the nano-carbon composite film by laser punching, and the spacing between the perforations is 0.2-0.5 cm; the diameter of the circular perforations is 0.1-0.3 cm.

2. The preparation method of the large-area flexible electric heating sheet according to claim 1, characterized in that: The sheet resistance of the nano-carbon composite film is 0.1-10 ohms.

3. The preparation method of the large-area flexible electric heating sheet according to any one of claims 1 to 2, characterized in that: The thickness of the nano-carbon composite film is 10-100 μm.

4. The preparation method of the large-area flexible electric heating sheet according to claim 1, wherein: The method of attachment is hot melt adhesive thermal composite attachment.

5. The preparation method of the large-area flexible electric heating sheet according to claim 4, characterized in that: The hot melt adhesive is at least one of polyurethane elastic rubber and EVA.

6. The preparation method of the large-area flexible electric heating sheet according to claim 1, wherein: The flexible conductive electrode is at least one of conductive wire, conductive metal foil and conductive cloth.

7. The preparation method of the large-area flexible electric heating sheet according to claim 1, characterized in that: The heat-conducting film is at least one of heat-conducting silicone grease film, graphene heat-conducting film, heat-conducting gel film and heat-conducting fabric film.

8. The preparation method of the large-area flexible electric heating sheet according to claim 1, characterized in that: The surface flexible substrate is at least one of fiber fabric, flexible silicone, heat storage material and reflective material.

9. An application of the preparation method of the large-area flexible electric heating sheet according to any one of claims 1 to 8, characterized in that: Applications of the preparation method of the flexible electric heating sheet in the preparation of large-area flexible electric heating sheets, water-washable flexible electric heating sheets and bend-resistant flexible electric heating sheets.

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