Safe and durable flexible heating sheet and preparation method thereof

Abstract

The invention belongs to the technical field of electric heating, and particularly relates to a safe and durable flexible heating sheet and a preparation method thereof.The flexible heating sheet comprises a heating layer, an adhesive film layer and a packaging layer, and the heating layer comprises a carbon nanotube film, a flexible circuit board and a protection layer; wherein two end parts of one side surface of the carbon nanotube film are adhered to the flexible circuit board, and two end parts of the other side surface of the carbon nanotube film are adhered to the protective layer; the flexible heating sheet has the advantages of good heating performance, washing resistance, bending resistance, rubbing resistance, softness and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of electric heating, and in particular relates to a safe and durable flexible heating sheet and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, heating technology, as an indispensable part of many fields, is constantly developing in the direction of higher efficiency, higher safety and higher flexibility. Traditional heating elements often have safety hazards such as overheating, short circuit and inability to wash, especially in harsh climate conditions, their service life will be greatly reduced, which has caused the development of the traditional heating industry to stagnate. Now, products with safety, tolerance and special heating functions have gradually stood out from many heating solutions and become the new favorites of the market.

[0003] Although the current heating elements use the highly popular graphene heating material, which can meet the functions of far-infrared and low-voltage design, there is a lot of resin material mixed inside the heating body, which makes the product itself less soft. After washing, a large number of hot spots appear in the heating temperature zone, which poses a risk of burns when used. In addition, there are still problems such as the safety of using resin materials in long-term heating environments and the harm to the human body.

[0004] Therefore, it is urgent to develop new heating elements that can achieve the functions of rapid heating, washability, bending resistance, rubbing resistance, softness, etc., and avoid the above-mentioned problems, and be safe to use in long-term heating environments without the hazards of chemical substance escape. Summary of the invention

[0005] The purpose of the present invention is to provide a safe and durable flexible heating sheet and a preparation method thereof, so as to solve the problems mentioned in the above background technology that the existing heating elements are difficult to withstand multiple washings, multiple bendings, rubbings, and are difficult to use normally under adverse weather conditions.

[0006] To achieve the above-mentioned purpose of the invention, the present invention provides a safe and durable flexible heating sheet, comprising a heating layer, a film layer, and a packaging layer, wherein the heating layer comprises a carbon nanotube film, a flexible circuit board, and a protective layer, wherein the two ends of one side of the carbon nanotube film are adhered to the flexible circuit board, and the two ends of the other side are adhered to the protective layer.

[0007] The core heating material carbon nanotube film used in the present invention has good anti-aging, flame retardant, high and low temperature resistance properties, and can maintain a stable heating effect even in harsh environments. The far infrared rays released by the carbon nanotube film during the heating process can also effectively relieve muscle pain, promote blood circulation, and play an auxiliary effect of heating therapy. The unique structural design of the present invention not only enables the heating plate to maintain good heating performance and structural integrity when subjected to external forces such as bending and folding, greatly extending the service life, but also meets the functions of water resistance, bending resistance, rubbing resistance, and softness. In addition, based on the uniqueness and complexity of the carbon nanotube film design, it has troubled many electric heating industry enthusiasts. The present invention also provides a carbon nanotube film heating plate and a preparation method thereof, which contributes more possibilities to the development of the electric heating industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the structure of the single-piece heating plate of the present invention.

[0009] Figure 2 It is a schematic diagram of the overall structure of the multi-plate heating plate of the present invention.

[0010] Figure 3 This is a schematic diagram of the structure of the circuit composition of the multi-plate heater of the present invention (the circuit is not protected).

[0011] Figure 4 It is a schematic diagram of the structure of the multi-plate heating plate after protecting the circuit of the present invention.

[0012] Figure 5 This is a SEM image of the carbon nanotube film of the present invention.

[0013] Figure 6 This is a graph showing the temperature change over time when the heater is connected to a 5V voltage.

[0014] Meaning of the accompanying figure numbers:

[0015] 1 packaging layer; 2 film layer; 3 heating element; 3a main axis heating element; 3b side heating element; 3c side heating element; 4 wire; 5 temperature control switch; 6 mobile power connector; 7 flexible circuit board; 8 conductive copper foil; 9 flexible substrate; 10 carbon nanotube film; 11 solder joint; 12 temperature measuring device; 13 power line; 14 signal line; 15 protective layer; 16 glue layer. DETAILED DESCRIPTION

[0016] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to 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 present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

[0017] In the context of the present invention, unless otherwise specified, the terms "heating element" and "heating sheet" are used interchangeably.

[0018] In the context of the present invention, unless otherwise specified, the term "single-piece heating plate" means that the heating plate includes one heating element, and the term "multi-piece heating plate" means that the heating plate includes more than one heating element, for example, two, three, four, five, or even more heating elements.

[0019] In the context of the present invention, when describing the structure of the heating sheet, in order to understand the structure more clearly and intuitively, sometimes the number corresponding to the reference numeral is added after the structure name. It should be understood that the structure is not limited to the form of the reference numeral, but also includes any other variations, modifications, etc. For example, when describing a single-piece flexible heating sheet, sometimes the number corresponding to the reference numeral is also applied. Figures 2 to 4 The corresponding structures in the multi-piece flexible heating sheet are numbered as the same structures are also present in the single-piece flexible heating sheet.

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] The present invention provides a safe and durable flexible heating sheet, comprising a heating layer, a film layer, and a packaging layer, wherein the heating layer comprises a carbon nanotube film, a flexible circuit board, and a protective layer, wherein the two ends of one side of the carbon nanotube film are adhered to the flexible circuit board, and the two ends of the other side are adhered to the protective layer.

[0022] In one embodiment, the flexible heating sheet of the present invention comprises an upper packaging layer 1 , an upper adhesive film layer 2 , a heating layer, a lower adhesive film layer 2 , and a lower packaging layer 1 .

[0023] In one embodiment, the flexible circuit board 7 in the heat generating layer of the present invention includes a conductive copper foil 8 and a flexible substrate 9 .

[0024] In one embodiment, both ends of one side of the carbon nanotube film 10 in the heat generating layer of the present invention are adhered to the conductive copper foil 8 , and both ends of the other side are adhered to the protective layer 15 .

[0025] In one embodiment, the heat generating layer comprises a plurality of carbon nanotube films. In one embodiment, the plurality of carbon nanotube films are arranged in parallel on the flexible circuit board.

[0026] In this article, horizontal refers to a relative orientation. For example, "the carbon nanotube film is arranged horizontally side by side on the flexible circuit board" means that when the carbon nanotube film and the flexible circuit board are both rectangular, the long side of the carbon nanotube film is parallel to the short side of the flexible circuit board; that is, the long side of the carbon nanotube film is attached to the flexible circuit board in a direction parallel to the short side of the flexible circuit board, for example Figure 3 shown.

[0027] In a specific embodiment, the heating layer of the present invention is further provided with a temperature measuring device 12. In one embodiment, the temperature measuring device 12 is attached to the surface of the carbon nanotube film. In one embodiment, one end of the temperature measuring device 12 is electrically connected to the signal line 14. In a specific embodiment, the temperature measuring device 12 and the signal line 14 are welded together. In a specific embodiment, one end of the temperature measuring device 12 is electrically connected to the signal line 14 at the welding point 11. In a preferred embodiment, the shape of the welding point 11 is circular or rectangular to achieve a firm welding. In a preferred embodiment, the size (diameter or length) of the welding point 11 is greater than 2 mm, depending on the size of the flexible heating sheet; for example, 2.2 mm-20 mm, preferably 2.5 mm-10 mm.

[0028] In a specific embodiment, a glue dispensing layer 16 is added at the position of the welding point 11 .

[0029] In one embodiment, the packaging layer 1, the adhesive film layer 2 and the heating layer 3 included in the flexible heating sheet of the present invention form an integrated pressed structure.

[0030] In one embodiment, the contact position between the carbon nanotube film included in the heat generating layer and the surface of the conductive copper foil 8 is coated with conductive silver paint.

[0031] In one embodiment, the bottom layer of the flexible substrate 9 included in the heating layer 3 is coated with organic silica gel, so as to facilitate the entire flexible circuit board 7 to be adhered to the adhesive film layer 2 .

[0032] In a specific embodiment, the temperature measuring device 12 included in the heating layer 3 is a chip thermistor. In a preferred embodiment, the chip thermistor can monitor the temperature of the surface of the carbon nanotube film in real time, transmit the acquired data to the control system, and automatically adjust the heating power to maintain a stable temperature.

[0033] In one embodiment, the square resistance of the carbon nanotube film is 0.3-5Ω / □, preferably 2-4Ω / □, and most preferably about 3Ω / □. In one embodiment, the carbon nanotube film is arranged at intervals, and the spacing is not less than 1 cm, which can avoid repeated accumulation of heat and heat loss. In one embodiment, the carbon nanotube film is arranged at intervals, and the spacing is 1 cm-20cm, preferably 2-5 cm, and most preferably 3 cm, depending on the size of the heating plate.

[0034] In one embodiment, the heating plate is electrically connected via the solder joints 11 on the flexible circuit board 7 and the corresponding polarities of the wires 4, and then the overall circuit of the heating plate is closed by connecting the partition films in series and in parallel.

[0035] In one embodiment, the heating sheet is prepared by using carbon nanotube films of different specifications to achieve different heating requirements. In one embodiment, the size of the carbon nanotube film is 1 mm-1000 mm, preferably 5 mm-500 mm, and more preferably 10 mm-100 mm.

[0036] In one embodiment, the flexible circuit board 7 included in the heat generating layer 3 is a polyimide-based flexible printed circuit board. In some embodiments, the polyimide-based flexible printed circuit board is selected from a steel sheet reinforced PI board or a copper-clad PI board.

[0037] In some embodiments, the circuit has been integrated on the surface of the substrate, and the flexible circuit board adds a PI reinforcement process at the gold finger position. In some embodiments, the PI reinforcement thickness is 0.1-0.5 mm, preferably 0.2 mm. In some embodiments, the bottom position of the polyimide flexible printed circuit board adopts a back glue, preferably tesa8853 high temperature resistant back glue. In some embodiments, the back glue thickness is 0.01-0.1 mm, preferably 0.05 mm.

[0038] In some embodiments, the surface steel sheet of the flexible circuit board is reinforced with a steel sheet. In some embodiments, the thickness of the reinforced steel sheet is 0.3-0.5 mm, preferably 0.4 mm.

[0039] In an embodiment in which the flexible circuit board 7 adopts a copper-clad PI board, the thickness of the copper-clad PI board is not less than 10 mm to ensure the current carrying capacity when a large current passes through.

[0040] In one embodiment, the material of the encapsulation layer 1 (upper encapsulation layer and lower encapsulation layer, if present) is a flame retardant lining cloth. In one embodiment, the flame retardant lining cloth has good flame retardancy and tensile strength, and meets the flame retardancy and rubbing resistance of the product. For example, the flame retardant lining cloth can be any type of flame retardant fabric, such as aramid knitted fabric, pre-oxidized silk non-woven fabric, preferably aramid knitted fabric.

[0041] In one embodiment, the adhesive film layer 2 is TPU adhesive film, PA adhesive film, EVA adhesive film, preferably TPU adhesive film (classified by material type). In another embodiment, the adhesive film layer is adhesive film, adhesive mesh film, and adhesive dot (classified by appearance).

[0042] In one embodiment, the protective layer 15 included in the heating layer is made of the same or different adhesive film as the adhesive film layer 2. In one embodiment, the protective layer 15 included in the heating layer 3 is TPU adhesive film, PA adhesive film, EVA adhesive film, preferably TPU adhesive film.

[0043] In a specific embodiment, the glue layer 16 included in the heating layer 3 is UV glue. In a specific embodiment, the glue layer 16 included in the heating layer 3 is acrylate UV glue. In a preferred embodiment, after applying the UV glue, the location of the solder joint 11 needs to be irradiated with an ultraviolet curing lamp for at least 120 seconds to ensure that the UV glue is cured so that the circuit meets the requirements of drawing and washing.

[0044] In a specific embodiment, the wire 4 is made of a four-new braided wire, and the wire outlet is tinned to prevent the wire from being oxidized and the contact resistance from increasing.

[0045] In one embodiment, the flexible heating sheet of the present invention is a single-piece heating sheet or a multi-piece heating sheet.

[0046] In an embodiment of a single-piece heater of the present invention, the voltage design range of the single-piece heater is 3-380V, preferably 5-220V.

[0047] In one embodiment of the present invention, the carbon nanotube films included in the heating plate are arranged in series or in parallel.

[0048] In an embodiment of a monolithic heating sheet of the present invention, the carbon nanotube films contained in the monolithic heating sheet are arranged in series or in parallel.

[0049] In an embodiment of a multi-plate heating plate of the present invention, the carbon nanotube films inside the main axis heating plate are arranged in series first and then in parallel, and the carbon nanotube films inside the side heating plate are arranged in series.

[0050] In an implementation scheme of a multi-piece heating plate of the present invention, the heating layer 3 of the multi-piece heating plate includes a main shaft heating element 3a, a side heating element 3b, a side heating element 3c, a wire 4, a temperature control switch 5, and a mobile power supply connector 6. The main shaft heating element 3a, the side heating element 3b and the side heating element 3c are arranged in parallel and are electrically connected through wires.

[0051] In an embodiment of a multi-plate heating plate of the present invention, the linear distance between the side heating body of the multi-plate heating plate and the main axis heating plate is adjusted according to the use effect, preferably not more than 2 m, and severe diversion will affect the heating effect.

[0052] In an embodiment of a multi-plate heating sheet of the present invention, the side heating element is electrically connected to the main shaft heating element in parallel. In an embodiment of a multi-plate heating sheet of the present invention, the arrangement position of the main shaft heating element and the side heating element can be arbitrary. In a specific embodiment, the arrangement position of the main shaft heating element and the side heating element can be, for example, Figure 3 In another specific embodiment, when there are more than two side heating bodies, the arrangement positions of more side heating bodies can be as shown in FIG. Figure 3 The side heating bodies are shown arranged side by side outwards.

[0053] In an embodiment of a multi-plate heating plate of the present invention, the voltage of the multi-plate heating plate may be 3-380V, preferably 5V.

[0054] The heating plate prepared by the invention can be used normally after being washed, bent and rubbed for many times and under adverse weather conditions.

[0055] In one embodiment, the temperature range of the heating plate of the present invention can be set to 30°C-60°C, preferably 35°C-55°C, which can achieve the function of heating.

[0056] The voltage of the heating plate of the present invention can be designed to be 5V-220V, and rapid heating can be achieved within 3 seconds after power-on, truly meeting the characteristics of low voltage energy saving, rapid heating and safety, and can also meet the functional requirements of water resistance, bending resistance, rubbing resistance, softness, etc.

[0057] It is worth mentioning that the electric-to-thermal conversion efficiency of the heating plate prepared based on the carbon nanotube film of the present invention can reach 99%. In a specific embodiment, the electric-to-thermal conversion efficiency of the heating plate of the present invention can reach 99.95% by 18V DC voltage test.

[0058] The total resistance of the carbon nanotube film series multi-piece heating is: R 总 =R 1 +R 2 +R 3 +...+R n When the resistance of each carbon nanotube film is equal, the resistance of a single film in series is R = R 总 / n, the resistance of a single film in parallel: R=R 总 n. The resistance of a single carbon nanotube film when the main circuit is connected in series and the branches are connected in parallel: R = (R 总 / n 串 )n 并, when the main carbon nanotube film is connected in parallel and the branch is connected in series: R= (R 总 / n 并 ) / n 串 , effective heating area of ​​carbon nanotube film: S 效 =S n / S 总 =lwn / (LW), power density of carbon nanotube film: p s =P / S 效 =P / (lwn), carbon nanotube film has different thicknesses, and the type of carbon nanotube film is selected by square resistance. The square resistance of carbon nanotube film is: R 方 =R / (l / w).

[0059] The above n represents the number of resistors in the circuit. 串 Represents the number of series resistors in the main circuit, n 并 represents the number of parallel resistors in the branch circuit, R represents the resistance of a single carbon nanotube film, L represents the length of the heating plate, W represents the width of the heating plate, S represents the area of ​​the heating plate, l represents the length of the carbon nanotube film, w represents the width of the carbon nanotube film, S 效 represents the effective heating area of ​​the carbon nanotube film, S n represents the heating area of ​​n carbon nanotube films, p s Represents the power density of the carbon nanotube film, which is a physical quantity that measures the temperature of the heating plate. 方 Represents the square resistance of the carbon nanotube film. 效 It means that the effective heating area of ​​the carbon nanotube film should be smaller than the area S of the heating plate.

[0060] Example

[0061] In order to better illustrate the content of the present invention, further description is given through examples.

[0062] Example 1: Preparation Figures 2 to 4 The multi-piece carbon nanotube thin film heating sheet test product shown.

[0063] The preparation of the carbon nanotube thin film heater is as follows:

[0064] 1. Cut the carbon nanotube film with a sheet resistance of 3Ω / □ into 8 strips with a length and width of 71*33 mm. After cutting, the carbon nanotubes in the carbon nanotube film are oriented along the long side as a whole;

[0065] 2. Cutting of flame retardant lining cloth for encapsulation layer: Cut 50D adhesive blank cloth into the size covering each heating element, with the adhesive side facing downwards.

[0066] The length and width of the main shaft heating element are 250*100 mm (1 set), and the length and width of the side heating element are 150*100 mm (2 sets)

[0067] 3. Laying and installation of heating sheet

[0068] a) Lay the FPC flexible circuit boards of the main shaft and the side heating element on the bottom lining cloth according to the corresponding positions;

[0069] b) Align one end (long side) of the carbon nanotube film with the circuit, and start pasting from the aligned end. The main axis heating element is laid with 4 carbon nanotube films, and the spacing between each is 20mm; the side heating element is laid with 2 carbon nanotube films, and the spacing between each is 20mm;

[0070] c) Flip up the carbon nanotube films at both ends of the electrode, then paint the electrode surface with conductive silver paint, and finally lay the flipped film flat on the electrode;

[0071] d) The contact signal end of the chip thermistor is placed in the middle of the first film on the side of the main shaft heating element close to the wire;

[0072] 4. Weld the power supply wire, side heating wire and signal wire at the electrode position (get Figure 3 Unprotected heat generating layer shown);

[0073] 5. Apply TPU film as a protective layer on both ends of the carbon nanotube film, and add an acrylic UV glue layer at the solder joints of all wires and thermistor signal wires. After glue application, irradiate the glue layer with an ultraviolet curing lamp for at least 120 seconds to ensure that the UV glue is cured (such as Figure 4 The protective heating layer shown);

[0074] 6. The encapsulation layer, the film layer and the heating layer are pressed together to form an integrated structure; the encapsulation layer lining cloth is hot-pressed with the TPU film as the film layer, the heating layer, the wire and the SMD thermistor at 130°C for 20s to obtain a carbon nanotube thin film heating plate with a smooth surface, no damage and no bubbles.

[0075] Example 2: Control Graphene Heater

[0076] Hydroxylated graphene oxide and boron nitride suspension are mixed in a ratio of 5:100, and graphene oxide slurry is prepared by ultrasonic treatment and mechanical shearing. Then, polyimide film or polyethylene terephthalate film is immersed in graphene oxide slurry, and graphene oxide slurry is evenly coated on polyimide film or polyethylene terephthalate film by centrifugation and other methods (after compounding, it is called graphene oxide composite film), and then the graphene oxide composite film is pre-reduced at low temperature, and the treatment temperature is stepwise increased to 260℃ for 8h. Finally, it is treated at 1500℃ for 3h in a nitrogen atmosphere, and then placed in a graphitization furnace at 2950℃ for 1h to sinter to obtain a graphene oxide composite film. Then, the graphene oxide composite film is superimposed on the copper chloride film, and the graphene heating unit is obtained by calendering for 40min by a flat press. Finally, the flexible fabric is hot-pressed on the surface of the heating unit to complete the production of the heating sheet.

[0077] The graphene heating sheet used in this experiment has a given voltage of 5V, a power of 10W, and a maximum temperature of 55°C. The parameters of the graphene heating sheet main axis heating sheet and the side heating sheet, such as size, line length, and material of the outer cloth layer, are consistent with those of the carbon nanotube film heating sheet.

[0078] Example 3: Pull-out test

[0079] Test purpose: To detect the tensile strength of the solder joint where the wire is connected to the heater.

[0080] Test objects: multi-piece carbon nanotube film heaters, graphene heaters.

[0081] Test steps: Connect the wire terminal on one side of the heating plate to the tensioner, and fix the fabric position on the other side of the heating plate on the test bench. Figure 3 The heater shown (unprotected) and Figure 4 The heating sheet (protected) shown was subjected to tensile testing. When the testing tensile forces were 5N, 10N, 30N, 50N and 80N respectively, the pulling time was 1min, and the temperature and power of the heating sheet after it was powered on for 1min were measured and the data were recorded.

[0082] Table 1 Tensile strength results of carbon nanotube film heater and graphene heater

[0083]

[0084] Example 4: Low temperature test

[0085] 1. Low temperature storage test

[0086] The test products are the carbon nanotube film heater and graphene heater prepared in Example 1, and the test steps are as follows:

[0087] will be in Figure 3 The heater shown (unprotected) and Figure 4 The test products in the heater plate (protection) state shown were hung in a low temperature (-40±3)℃ environment (without power supply), taken out after 96 hours, and then placed in a room temperature (23±2)℃ environment for 24 hours. The heater plate performance was checked under the test voltage, and the results are summarized in the following Table 2.

[0088] (II) Low temperature working test:

[0089] The carbon nanotube film heater and graphene heater prepared in Example 1 were placed in a low temperature environment (-40±3)°C. After working continuously for 96 hours under the test voltage, the heater performance was checked. The results are summarized in Table 2 below.

[0090] Test requirements: The heater and its components should work normally without open circuit, short circuit, scorch marks, abnormal heating, leakage, shedding, cover layer damage and other failures. The resistance deviation of the heater should not exceed ±10% of the initial value.

[0091] Table 2 Data results of low temperature storage test and low temperature working test

[0092]

[0093] Example 5: High temperature test

[0094] 1. High temperature storage test:

[0095] The test products are the carbon nanotube film heater and graphene heater prepared in Example 1, and the test steps are as follows:

[0096] will be in Figure 3 The heater shown (unprotected) and Figure 4 The test products in the heating plate (protection) state shown were hung in a high temperature (90±3)℃ environment (without power supply), taken out after 96 hours, and then placed in a normal temperature (23±2)℃ environment for 24 hours. The performance of the heating plate was checked under the test voltage. The results are summarized in Table 3 below.

[0097] (II) High temperature working test:

[0098] The carbon nanotube film heater and graphene heater prepared in Example 1 were placed in a high temperature environment (90±3)°C. After working continuously for 96 hours under the test voltage, the heater performance was checked. The results are summarized in Table 3 below.

[0099] Test requirements: The heater and its components should work normally without open circuit, short circuit, scorch marks, abnormal heating, leakage, shedding, cover layer damage and other failures. The resistance deviation of the heater should not exceed ±10% of the initial value.

[0100] Table 3 High temperature storage test and high temperature working test data results

[0101]

[0102] Example 6: Water washing test

[0103] The test product is the carbon nanotube film heater prepared in Example 1, and the test steps are as follows: Figure 4 The heating plate shown is placed in a washer-dryer drum washing machine, the washing temperature is set to 40°C, the washing time is 60 minutes, the drying temperature is 80°C, the drying time is 60 minutes, and it is washed 15 times. The performance of the heating plate is checked once every 5 washes, and a total of 3 tests are conducted. The results are summarized in Table 4 below.

[0104] In addition, the graphene heating plate of Example 2 of the present invention cannot be washed with water, and power abnormality occurs after washing twice.

[0105] Test requirements: After washing, test whether it can be used normally, and after 15 times of washing, the power attenuation is less than 30%, and the temperature attenuation is less than 5°C.

[0106] Table 4 Water washing test data results

[0107]

[0108] Example 7: Temperature Rising Test

[0109] The test product is the carbon nanotube thin film heater prepared in Example 1, and the test steps are as follows:

[0110] The type C interface of the carbon nanotube film heater finally prepared in Example 1 was inserted into the type C interface of the AC / DC parameter measuring instrument, and the voltage was adjusted to 5 V. The position of the carbon nanotube film was found by an infrared thermal imager, and then the thermocouple wire of the temperature measuring instrument was fixed in the area with the carbon nanotube film to detect the temperature rise of the heater. The results are summarized in the following Table 5 and the attached Figure 6 middle.

[0111] Table 5 Temperature variation of the carbon nanotube film heater with time when 5V voltage is applied

[0112]

[0113] Table 5 and Figure 6It shows that the temperature of the heating plate begins to rise within 3 seconds of power-on, and the temperature rises by at least 10 degrees in the first minute of power-on. It rises to 90% of the maximum temperature within 1 minute, which is higher than the industry standard (i.e., rising to 90% of the maximum temperature within 3 minutes). It reaches the maximum temperature (55±1℃) and stabilizes in 5 minutes.

Claims

1. A safe and durable flexible heating sheet, comprising a heating layer, a film layer, and a packaging layer, wherein the heating layer comprises a carbon nanotube film, a flexible circuit board, and a protective layer, wherein the two ends of one side of the carbon nanotube film are adhered to the flexible circuit board, and the two ends of the other side are adhered to the protective layer. 2 . The flexible heating sheet according to claim 1 , wherein the flexible circuit board 7 comprises a conductive copper foil 8 and a flexible substrate 9 . 3 . The flexible heating sheet according to claim 2 , wherein both ends of one side of the carbon nanotube film are adhered to the conductive copper foil 8 on the flexible circuit board 7 . 4 . The flexible heating sheet according to claim 1 , wherein the heating layer comprises a plurality of carbon nanotube films arranged in parallel and spaced relation on a flexible circuit board. 5 . The flexible heating sheet according to claim 4 , wherein the spacing between the plurality of carbon nanotube films arranged in parallel and spaced apart is 1 cm-20 cm, preferably 2-5 cm, and most preferably 3 cm.

6. The flexible heating sheet according to any one of claims 1 to 5, wherein the heating layer is further provided with a temperature measuring device. 7 . The flexible heating sheet according to claim 1 , wherein the adhesive film layer is a TPU adhesive film, a PA adhesive film, or an EVA adhesive film, preferably a TPU adhesive film.

8. The flexible heating sheet according to any one of claims 1 to 7, wherein the thickness of the adhesive film layer is 10-30 μm, preferably 15-25 μm, and most preferably 18-22 μm. 9 . The flexible heating sheet according to claim 1 , wherein the flexible heating sheet is a single-piece or multi-piece sheet.

10. The flexible heating sheet according to any one of claims 1 to 9, wherein the sheet resistance of the carbon nanotube film is 0.3-5Ω / □, preferably 2-4Ω / □, and most preferably about 3Ω / □.

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