Flexible explosion-proof heating pad with PTC (Positive Temperature Coefficient) characteristic

Abstract

A flexible explosion-proof heating pad with PTC characteristics belongs to the technical field of explosion-proof heating and comprises a PTC heating film, protective layers and a power connector, the power connector is electrically connected with the PTC heating film, and the protective layers are arranged on the upper surface and the lower surface of the PTC heating film; the protective layer comprises a heat-resistant protective layer and a conductive layer, the conductive layer is arranged on one surface, far away from the PTC heating film, of the heat-resistant protective layer on the same surface, and the conductive layer is electrically connected with the power connector; the PTC heating film made of the PET base material serves as a heating body, so that the final product has the PTC self-temperature-limiting characteristic, and the surface temperature requirement of T5 is met under the condition that a temperature control device does not exist. And a temperature control device is omitted, so that the cost and complexity of the product are reduced, and the reliability of the product is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of explosion-proof heating, and specifically refers to a flexible explosion-proof heating pad with PTC characteristics. Background Art

[0002] In the existing technology, non-metallic matrix infrared radiation heaters that meet GB / T4654 have the advantages of low cost and good designability. Some products also have certain PTC characteristics. The maximum surface temperature of the product can be controlled between T5 and T6 without the need for a thermostat, which has higher safety. However, such non-metallic matrix infrared radiation heaters generally cannot meet the relevant explosion-proof requirements of GB3836.1. The main reason is that the protection level of such products is weak and cannot meet the requirements of 7.4 "electrostatic charge of external non-metallic materials" and 26.4.2 "impact test" in the shell protection of GB3836.1 standard. Summary of the invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, an embodiment of the present invention provides a flexible explosion-proof heating pad with PTC characteristics, which at least partially solves the above technical problems.

[0004] The technical solution adopted by the embodiment of the present invention is as follows: a flexible explosion-proof heating pad with PTC characteristics, comprising a PTC heating film, a protective layer, and a power connector, wherein the power connector is electrically connected to the PTC heating film, and the protective layer is arranged on the upper and lower surfaces of the PTC heating film; The protective layer comprises a heat-resistant protective layer and a conductive layer. The conductive layer is arranged on a side of the heat-resistant protective layer away from the PTC heating film, and the conductive layer is electrically connected to a power connector.

[0005] Furthermore, it also includes a conductive silicone layer, which is connected to the side of the same conductive layer away from the PTC heating film.

[0006] Furthermore, the PTC heating film, heat-resistant protective layer, conductive layer and conductive silicone layer are all made of flexible materials.

[0007] Furthermore, the PTC heating film, the heat-resistant protective layer, the conductive layer and the conductive silicone layer are all connected by adhesive connection.

[0008] Furthermore, the thickness of the heating pad is 2-6 mm.

[0009] Furthermore, the heat-resistant protective layer is made of a polyimide film, and the thickness of the heat-resistant protective layer is 1-3 mm.

[0010] Furthermore, the conductive layer is made of aluminum foil, and the thickness of the conductive layer is 0.05-0.2 mm.

[0011] Furthermore, the thickness of the conductive silicone layer is 0.05-0.2 mm.

[0012] Furthermore, the power connector adopts a three-wire power connector, wherein the live wire and the neutral wire are electrically connected to the PTC heating film respectively, and the ground wire is electrically connected to the conductive layers on both sides respectively; It also includes a connector protection shell, which is connected to the power connector.

[0013] The beneficial effects achieved by the present invention using the above structure are as follows: The present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic, and meets the surface temperature requirement of T5 without the temperature control device. The temperature control device is eliminated, the cost and complexity of the product are reduced, and the reliability of the product is improved.

[0014] The present invention can effectively meet the explosion-proof requirements related to GB3836.1 by respectively arranging a heat-resistant protective layer, a conductive layer and a conductive silicone layer on both sides of the PTC heating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an appearance diagram of an embodiment of the present invention; Figure 2 An exploded view of an embodiment of the present invention; In the figure: 1-PTC heating film; 2-heat-resistant protective layer; 3-conductive layer; 4-conductive silicone layer; 5-power connector.

[0016] The accompanying drawings are used to provide further understanding of the embodiments of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] In the description of the embodiments of the present invention, it should be understood that terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0019] Traditional PET-based heating films, such as the heating films described in patent ZL201410752740.0, can be made to have PTC characteristics by using specific thermosensitive materials as heating elements, such as using thermosensitive conductive inks described in patent ZL201410751990.2. This heating film with PTC characteristics can control the surface temperature at T5~T6 level without a temperature control device, and has high safety. At the same time, the lack of a temperature control device reduces the complexity and cost of the product.

[0020] It should be noted that T5 and T6 in the surface temperature T5~T6 are groups in the explosion-proof field, which are used to classify the ability of electrical equipment to prevent ignition of surrounding explosive gas mixtures under specific temperature conditions. Explosion-proof temperature groups T1 to T6 correspond to different maximum surface temperatures. These temperature groups are important criteria for evaluating the explosion-proof ability of electrical equipment under specific temperature conditions; Definition of explosion-proof temperature groups: T1: maximum surface temperature ≤ 450°C; T2: maximum surface temperature ≤ 300°C; T3: maximum surface temperature ≤ 200°C; T4: maximum surface temperature ≤ 135°C; T5: maximum surface temperature ≤ 100°C; T6: maximum surface temperature ≤ 85°C.

[0021] like Figure 1 and Figure 2 As shown, the present invention provides a flexible explosion-proof heating pad with PTC characteristics, including a PTC heating film 1, a protective layer, and a power connector 5, wherein the power connector 5 is electrically connected to the PTC heating film 1, and the protective layer is arranged on the upper and lower surfaces of the PTC heating film 1; The protective layer comprises a heat-resistant protective layer 2 and a conductive layer 3 . The conductive layer 3 is arranged on a side of the heat-resistant protective layer 2 away from the PTC heating film 1 . The conductive layer 3 is electrically connected to a power connector 5 .

[0022] It should be noted that: the present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic and meets the surface temperature requirement of T5 without a temperature control device.

[0023] In a further implementation of this embodiment, a conductive silicone layer 4 is further included. The conductive silicone layer 4 is connected to a surface of the conductive layer 3 on the same surface away from the PTC heating film 1 .

[0024] It should be noted that conductive silicone is pasted on the surfaces of the upper and lower aluminum foils to further improve the protection capability of the product and at the same time meet the surface electrostatic charge requirements of explosion-proof electrical products.

[0025] In a further implementation of this embodiment, the PTC heating film 1, the heat-resistant protective layer 2, the conductive layer 3 and the conductive silicone layer 4 are all made of flexible materials. The PTC heating film 1, the heat-resistant protective layer 2, the conductive layer 3 and the conductive silicone layer 4 are all connected by adhesive connection. The thickness of the heating pad is 2-6mm. The heat-resistant protective layer 2 is made of polyimide film, and the thickness of the heat-resistant protective layer 2 is 1-3mm. The conductive layer 3 is made of aluminum foil film, and the thickness of the conductive layer 3 is 0.05-0.2mm.

[0026] It should be noted that by using flexible materials to meet the needs of flexible heating pads in practical applications, the explosion-proof requirements can be effectively increased by selecting the above-mentioned layer thickness.

[0027] Experimental test 1 The thickness of the conductive silicone layer is set to four levels of 0 mm, 0.05 mm, 0.1 mm, and 0.2 mm for the flexible heating pad; Flexible heating pads with and without aluminum foil layers are provided, and flexible heating pads with protective layers having four levels of thickness of 1 mm, 1.5 mm, 2 mm, and 3 mm are provided.

[0028] The above-mentioned flexible heating pads were tested respectively using the test method of Appendix C of GB 3836.1-2021, with a drop height of 700 mm.

[0029] The qualification criteria are: 1. Insulation resistance before and after the test ≥ 2000MΩ; 2. The product can achieve surface grounding.

[0030] The test results are shown in Table 1 below. Table 1

[0031] From the data in Table 1 above, it can be seen that samples 12, 13, 17, and 18 have sufficient protection levels and can meet the requirements for explosion-proof mechanical protection performance. However, samples without protection or with low thickness of the protective layer cannot meet the protection requirements.

[0032] Experimental test 2 Samples with 10 structures were selected. According to Table 17 of GB 3836.1-2021, the samples were aged for 336 h in an environment of 90 °C and 95% hr humidity, and then dried at 100 °C for 336 h.

[0033] According to Appendix C of GB 3836.1-2021, the impact characteristics are tested at a drop height of 700 mm.

[0034] According to GB / T19518-2017 5.1.13.3, the maximum surface temperature of the test sample.

[0035] Qualification judgment basis: insulation resistance before and after the test ≥ 2000MΩ, the maximum surface temperature of the test sample does not exceed 100℃.

[0036] The test data are shown in Table 2 below: Table 2

[0037] Test conclusion: 10 The structural specimens have sufficient protection level after the accelerated aging test and can meet the requirements of explosion-proof mechanical protection performance.

[0038] The preparation method of the PTC heating film is as follows: Printing a silver paste layer on one side of the PET base film to obtain a silver paste printed coil; Printing a carbon paste layer on the side of the silver paste printed coil away from the PET base film to obtain a silver and carbon paste printed coil; Thermally laminating a first adhesive film layer on the side of the silver-printed and carbon-paste coil away from the PET base film to obtain a PTC base film; Attaching a metal shielding layer on the side of the PTC base film away from the PET base film; Attaching a second adhesive film layer on a side of the metal shielding layer away from the PET base film; A double-sided adhesive tape is attached to the side of the second adhesive film layer away from the metal shielding layer to obtain a PTC heating film.

[0039] The silver paste layer is printed on the PET base film by screen printing, and the silver paste layer is dried and solidified after printing. Then the carbon paste layer is printed on the side of the carbon paste layer away from the PET base film by screen printing, and the carbon paste layer is dried and solidified after printing before proceeding to the next process.

[0040] The invention also includes: cutting the PTC heating film into a product shape by die cutting; Cold-press riveting the wire harness terminal to the silver paste layer electrode of the die-cut PTC heating film; Use glue to encapsulate the exposed electrode area; After measuring the resistance of the packaged PTC heating film with a multimeter, thermal imaging is used to perform infrared detection when it is powered on.

[0041] PI films are pasted on the upper and lower surfaces of PET insulating materials to improve the heat resistance of the material at high temperatures.

[0042] Conductive aluminum foil is pasted on the upper and lower PI film surfaces, and the conductive aluminum foil is grounded to meet the grounding requirements of explosion-proof electrical equipment.

[0043] In a further implementation of this embodiment, the thickness of the conductive silicone layer 4 is 0.05-0.2 mm.

[0044] In a further implementation of this embodiment, the power connector 5 adopts a three-wire power connector, wherein the live wire and the neutral wire are electrically connected to the PTC heating film 1 respectively, and the ground wire is electrically connected to the conductive layers 3 on both sides respectively; It also includes a connector protection shell, which is connected to the power connector 5.

[0045] It should be noted that the present invention uses the PTC heating film of the PET substrate as the heating element, so that the final product has the PTC self-limiting temperature characteristic, and meets the surface temperature requirement of T5 without the temperature control device. The temperature control device is eliminated, the cost and complexity of the product are reduced, and the reliability of the product is improved.

[0046] PI films are pasted on the upper and lower surfaces of PET insulation materials to improve the heat resistance of the material at high temperatures, so that the product will not fail in insulation during high temperature impact testing.

[0047] Aluminum foil and conductive silicone are pasted on the upper and lower surfaces to further improve the product's protection capabilities and meet the surface electrostatic charge requirements of explosion-proof electrical products. The product surface resistance can be less than 1G ohm (under relative humidity 50% rh).

[0048] The present invention mainly protects the specific multi-layer structure of the product, which can make the conventional heating film meet the explosion-proof requirements.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0050] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0051] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the creative purpose of the embodiments of the present invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A flexible explosion-proof heating pad with PTC characteristics, characterized in that: It includes a PTC heating film, a protective layer, and a power connector, wherein the power connector is electrically connected to the PTC heating film, and the protective layer is arranged on the upper and lower surfaces of the PTC heating film; The protective layer comprises a heat-resistant protective layer and a conductive layer. The conductive layer is arranged on a side of the heat-resistant protective layer away from the PTC heating film, and the conductive layer is electrically connected to a power connector.

2. The flexible explosion-proof heating pad with PTC characteristics according to claim 1 is characterized in that: It also includes a conductive silicone layer, which is connected to the side of the conductive layer on the same side away from the PTC heating film.

3. The flexible explosion-proof heating pad with PTC characteristics according to claim 2, characterized in that: The PTC heating film, the heat-resistant protective layer, the conductive layer and the conductive silicone layer are all made of flexible materials.

4. The flexible explosion-proof heating pad with PTC characteristics according to claim 2 is characterized in that: The PTC heating film, the heat-resistant protective layer, the conductive layer and the conductive silicone layer are all connected by adhesive connection.

5. The flexible explosion-proof heating pad with PTC characteristics according to claim 2 is characterized in that: The thickness of the heating pad is 2-6 mm.

6. The flexible explosion-proof heating pad with PTC characteristics according to claim 5, characterized in that: The heat-resistant protective layer is made of polyimide film, and the thickness of the heat-resistant protective layer is 1-3 mm.

7. The flexible explosion-proof heating pad with PTC characteristics according to claim 5, characterized in that: The conductive layer is made of aluminum foil film, and the thickness of the conductive layer is 0.05-0.2 mm.

8. The flexible explosion-proof heating pad with PTC characteristics according to claim 5, characterized in that: The thickness of the conductive silicone layer is 0.05-0.2 mm.

9. The flexible explosion-proof heating pad with PTC characteristics according to claim 1, characterized in that: The power connector adopts a three-wire power connector, wherein the live wire and the neutral wire are electrically connected to the PTC heating film respectively, and the ground wire is electrically connected to the conductive layers on both sides respectively; It also includes a connector protection shell, which is connected to the power connector.

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