Self-temperature-limiting heating film

Abstract

The utility model provides a self-temperature-limiting heating film, and belongs to the field of electric heating materials. The self-temperature-limiting heating film comprises a lower packaging layer, a base material layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer which are sequentially arranged in the thickness direction. The conductive layer and the temperature limiting layer are connected in parallel to form the temperature limiting heating composite layer, the resistance value of the whole electric heating film is driven to be increased by increasing the resistance value of the temperature limiting layer so as to achieve the temperature limiting function, the self-temperature-limiting heating film integrates shielding, temperature limiting and heating, and the problems that a brake cannot be closed, and tripping occurs can be solved.

Description

Technical Field

[0001] The present application belongs to the field of electric heating materials, and in particular relates to a self-limiting temperature heating film. Background Art

[0002] Electric heating is an emerging winter heating method. Electric heating technology converts electrical energy directly into thermal energy. Because electric energy has the advantages of being noiseless and pollution-free, electric heating has its outstanding characteristics compared to traditional boilers.

[0003] At present, the main methods of electric heating include heating cables, electric heating films, electric boilers, etc. Heating cables are made into cable structures, using electricity as energy, and using alloy resistance wires or carbon fiber wires as heating elements. When powered on, they generate heat to achieve the effect of heating or insulation. The use of heating cables for heating has the problem of increasing electricity capacity, especially for large households, and the installation costs and procedures are relatively cumbersome. An electric boiler is a mechanical device that uses the combustion of electricity as energy and utilizes the principles of resistance heating or electromagnetic induction heating to heat the heat medium water or organic heat carrier to certain parameters, and then outputs heat energy with a certain working fluid to the outside. However, boilers are high-temperature and high-pressure thermal energy equipment, and are one type of special equipment. A special equipment installation and maintenance qualification certificate must be obtained before engaging in the installation, maintenance, and modification of boilers. Therefore, the promotion and application of this technology involve many complex engineering problems.

[0004] Electric heating film is a thin film that generates heat when electricity is applied. It is a planar heating material that generates heat evenly and has higher heating efficiency. Therefore, electric heating film is gradually being used on a large scale in electric heating. However, most conductive heating devices currently on the market do not have a temperature limit function. Electric heating is directly related to people's living environments, and furniture or items that require a large area will inevitably be placed directly on the ground. After being placed for a long time, the heat generated by the electric heating film below cannot be dissipated, and the temperature will easily rise after the heat is accumulated. Therefore, it is necessary to add a temperature limit switch or probe to ensure the safe use of the electric heating film. At the same time, the electric heating film itself has no shielding function. The method of laying an additional shielding layer not only increases the laying time and material costs, but also causes problems such as tripping and failure to close the switch due to factors such as moisture during the wet laying process.

[0005] In view of this, this application is hereby filed. Utility Model Content

[0006] The purpose of this application is to provide a self-limiting temperature heating film, which adopts a conductive layer and a temperature limiting layer in parallel to form a temperature limiting heating composite layer. The resistance of the entire electric heating film increases by increasing the resistance of the temperature limiting layer, thereby achieving the temperature limiting function to solve the above problems.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] A self-limiting temperature heating film (also called a heating film) comprises a lower packaging layer, a substrate layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer arranged in sequence in the thickness direction.

[0009] Furthermore, the PTC layer, ie, the temperature limiting layer, includes a phase change material; optionally, the thickness of the PTC layer is 500-1500 μm.

[0010] Preferably, the self-temperature-limiting heating film further includes a shielding layer, and the shielding layer is provided between the lower packaging layer and the substrate layer or between the electrode layer and the upper packaging layer.

[0011] Furthermore, the shielding layer comprises a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS film. More preferably, the PEDOT:PSS film is treated with sulfuric acid. The shielding layer is connected to a ground line to shield the temperature-limiting layer from potential leakage current.

[0012] Optionally, the thickness of the shielding layer is 3-100 um.

[0013] The upper and lower packaging layers and the substrate are generally made of PET, BOPET, PI, PC and the like, and their main functions are insulation, waterproofing, and protection of the internal structure.

[0014] This application also provides a method for preparing the self-limiting temperature heating film:

[0015] applying a coating liquid on one side of the substrate layer to form a treatment layer;

[0016] physically depositing a conductive layer on the handle layer;

[0017] Preparing a PTC layer on the conductive layer by screen printing and drying; preferably, the drying temperature is 80-180° C.;

[0018] preparing interdigitated electrodes and laminating them on the PTC layer to form an electrode layer;

[0019] The lower packaging layer and the upper packaging layer are respectively combined with the substrate layer and the electrode layer to perform packaging and insulation.

[0020] Preferably, the preparation method further comprises coating a PEDOT:PSS film on the other side of the substrate layer to form a shielding layer, and then performing encapsulation and insulation with a lower encapsulation layer; or,

[0021] As a parallel technical solution, the preparation method may also further include coating a PEDOT:PSS film on the side of the electrode layer facing the upper packaging layer to form a shielding layer, and then performing packaging and insulation with the upper packaging layer.

[0022] Furthermore, the PEDOT:PSS film is coated and then treated with sulfuric acid to increase conductivity.

[0023] Optionally, the coating method of the PEDOT:PSS film is spin coating.

[0024] The sulfuric acid treatment rearranged the PEDOT:PSS film's microstructure, increasing its conductivity fivefold compared to that of the films treated with formic and oxalic acids. This is because sulfuric acid induces structural rearrangement of the PEDOT:PSS film through a charge separation transition mechanism, forming highly ordered and densely packed PEDOT:PSS nanofibers. This increases the carrier concentration and, consequently, enhances conductivity.

[0025] Preferably, the concentration of the sulfuric acid is 50-75%.

[0026] Optionally, the coating liquid can be one or more of polyester, polyurethane, acrylic, silicone solution, etc. Preferably, after the coating liquid is applied, it is dried at 60-100°C; the thickness of the treatment layer is 1-8um. During the drying process, the water in the coating liquid evaporates, and eventually a uniform chemical treatment layer is formed on the surface of the substrate film. The treatment layer increases the adhesion, allowing the conductive material deposited by physical deposition to better adhere to the substrate, providing a uniform plane for the entire heating film structure, which is beneficial to stable performance.

[0027] A conductive layer of 10-100 nm is formed on the treated layer by physical deposition (such as radio frequency magnetron sputtering, pulsed laser deposition, vacuum evaporation and molecular beam epitaxy) using low resistivity materials (one or more of copper, cadmium, aluminum, titanium, tungsten, tin, indium tin oxide, fluorine-doped tin oxide and aluminum-doped zinc oxide) in a high vacuum environment.

[0028] Furthermore, the method for preparing the slurry of the PTC layer includes:

[0029] After adding an emulsifier to paraffin for dispersion, silicon dioxide, copolymerized methyl methacrylate and acrylic acid are added (due to the principle of similar polarity compatibility, the later added solution will be wrapped on the surface of the paraffin droplets during the stirring process). After adding an initiator, free radical polymerization initiates polymerization of monomer double bonds and double bonds on the surface of silicon dioxide to obtain a phase change material with a paraffin core and a particle size of about 10-38 μm; graphene is dispersed in an organic solvent, and then a polymer matrix and the phase change material are added, and then aluminum oxide, polyacrylate, titanium dioxide and ethanol are added, and stirred or dispersed evenly to obtain the product.

[0030] Effective doping with an appropriate amount of aluminum oxide prevents excessive stacking and agglomeration of graphene powder, preserving its structure and excellent conductive properties. Due to the slurry's viscosity, the surface is prone to ripples and unevenness during coating. However, the alkyl side chains in the polyacrylate quickly escape to the surface, forming a monolayer. This increases the density of the oriented molecular structure, making the surface tension more uniform and mitigating the potential for ripples on the coated surface caused by uneven tension throughout the PTC slurry. The Ti-O bond in titanium dioxide is highly polar. Water adsorbed on the surface dissociates due to polarization, forming hydroxyl groups. These groups can adsorb polar particles, imparting a charge to the solid surface and forming an electrical double layer. Because the charges are like, like charges repel and disperse, improving the overall stability of the PTC slurry. The hydroxyl groups (-OH) in ethanol molecules impart good hydrophilicity and solvent properties. They interact with other molecules throughout the slurry, reducing interfacial tension and establishing stable interactions with the dispersed materials through hydrogen bonding or van der Waals forces, further inhibiting aggregation and sedimentation of the conductive carbon particles. The emulsifier is generally selected from sorbitan monooleate polyoxyethylene ether.

[0031] Furthermore, in terms of weight, the paraffin wax, emulsifier, silicon dioxide, copolymerized methyl methacrylate, acrylic acid, graphene, polymer matrix, aluminum oxide, titanium dioxide, polyacrylate and ethanol are 10-20 parts, 0.5-1 parts, 0.3-0.8g parts, 6-10g parts, 1-5 parts, 25-50 parts, 80-100 parts, 0.6-10 parts, 6-10 parts, 15-20 parts and 18-20 parts respectively.

[0032] Optionally, the screen printing uses a 150-500 mesh screen.

[0033] The conductive layer and the PTC layer are stacked together to form a conductive heating layer. Then, a metal foil with conductive adhesive is physically laser-etched to create interdigitated electrodes, which are then bonded to the PTC layer. Finally, upper and lower packaging layers are used for insulation.

[0034] The resistance detected by interdigitated electrodes is more sensitive than that of two conventional electrodes. Even slight resistance changes between the interdigitated electrodes can be detected with greater sensitivity and a faster response. Furthermore, this can enhance the bonding strength with the packaging material and slurry. Furthermore, the room-temperature resistance of the PTC layer, which is in direct contact with the interdigitated electrodes, is relatively high. Adjusting the spacing and width of the interdigitated electrodes allows the resistance of the entire conductive heating layer to be adjusted.

[0035] The self-limiting temperature heating film of the present application contains two functional layers with different resistance values, and the resistance values ​​of these two layer structures are connected in parallel to form the resistance value of an integrated conductive heating layer. The resistance value of the conductive layer is stable, the PTC layer is formed by graphene powder to form a carbon chain for conductivity, and the phase change material it contains has the function of heat storage. When the temperature gradually rises to around a specific temperature, the paraffin core of the phase change material absorbs heat from a solid to a liquid, and the paraffin core wall material and the polymer will expand due to the swelling characteristics, causing the carbon chain to break and form high resistance, which increases the overall resistance of the conductive heating layer, and the current decreases, which ultimately affects the continuous heating of the conductive heating layer to achieve the temperature limiting function. When the temperature of the heating film decreases, the paraffin core wall material and the polymer shrink to form a loop of the conductive carbon chain, the resistance decreases, the current increases, and the temperature of the heating film increases.

[0036] Optionally, the interdigitated electrodes are prepared by physically preparing interdigitated electrodes with a certain spacing by laser etching a metal foil with a thickness of 30-100 um and a conductive adhesive.

[0037] Optionally, the packaging is performed by hot pressing or cold pressing to provide insulation.

[0038] Compared to existing technologies, this application utilizes a conductive layer and a temperature-limiting layer in parallel to form a temperature-limiting heating layer, adjusting the resistance of the electric heating film. As the temperature rises, the resistance of the temperature-limiting layer increases, thereby increasing the resistance of the entire electric heating film, achieving the temperature-limiting function. Furthermore, the temperature-limiting layer contains a heat-storage phase-change material. Once the electric heating film has generated heat and stored heat, the paraffin core and polymer expand at a specific temperature, achieving the temperature-limiting function. Furthermore, the use of a planar temperature-limiting layer improves safety.

[0039] PEDOT:PSS film is used as a shielding layer to connect to the ground wire, shielding the temperature-limiting heating layer from potential leakage current. Furthermore, its lower thermal conductivity than commonly used metal shielding layers facilitates single-sided heating.

[0040] The self-limiting temperature heating film prepared in the present application integrates shielding, temperature limiting and heating, which can reduce problems such as failure to close the switch and tripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 This is a schematic diagram of the explosion of the layered structure of the self-limiting temperature heating film in Example 1 of the present application;

[0043] Figure 2 This is the structural intention of the paraffin core phase change material of Example 1 of this application;

[0044] Figure 3 The temperature rise diagram of the heating film of Example 1 and Comparative Example 1;

[0045] Figure 4 This is a diagram of power-off cooling of the heating film of Examples 1, 2 and Comparative Example 1;

[0046] Figure 5 This is a schematic diagram of the explosion of the layered structure of the self-limiting temperature heating film of Example 6 of the present application.

[0047] Description of reference numerals:

[0048] 1. Upper packaging layer; 2. Electrode layer; 3. PTC layer; 4. Conductive layer; 5. Treatment layer; 6. Base material layer; 7. Shielding layer; 8. Lower packaging layer; 9. Paraffin layer; 10. Inner wall material; 11. Outer wall material. DETAILED DESCRIPTION

[0049] The following describes the examples of the present application in detail. All substances and raw materials in the examples are commercially available products. Unless otherwise specified, all ratios are mass ratios and arbitrary ratios.

[0050] As used herein:

[0051] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0052] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0053] In these examples, parts and percentages are all by weight unless otherwise specified. Elements not described, such as the thickness of each layer, should be understood to be within the skill of the art.

[0054] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0055] Example 1

[0056] A self-limiting temperature heating film comprises: a lower packaging layer 8, a shielding layer 7, a substrate layer 6, a processing layer 5, a conductive layer 4, a PTC layer 3, an electrode layer 2 and an upper packaging layer 1, such as Figure 1 shown.

[0057] The preparation method thereof comprises:

[0058] (1) 15 g of paraffin wax and 0.8 g of sorbitan monooleate polyoxyethylene ether were melted at 65 ° C, and 135 ml of deionized water was added and dispersed at a speed of 3000 r / min for 10 min. Then, a mixture of 0.5 g of silicon dioxide, 8 g of copolymerized methyl methacrylate and 3 g of acrylic acid was added to obtain a phase change material (such as Figure 2 As shown, it includes a paraffin layer 9, an inner wall material 10, and an outer wall material 11, which are sequentially coated from the inside out; the inner wall material 10 is mainly copolymerized methyl methacrylate and acrylic acid, and the outer wall material 11 is mainly silicon dioxide. 35g of graphene powder is dispersed in 70g of dimethylformamide (DMF), and the obtained phase change material, 90g of acrylate, and polyurethane emulsion are added thereto. 0.8g of aluminum oxide, 8g of titanium dioxide, 18g of acrylic emulsion, and 19g of ethanol are then added in sequence, and a PTC slurry is prepared by mechanical stirring.

[0059] (2) Clean both sides of the substrate with purified water and ethanol and then dry them thoroughly;

[0060] (3) Coating the polyester and silicon solution coating liquid on the surface of the substrate with a roller, and then drying at 80°C to form a treatment layer 5 of about 6 μm to increase the stability and flatness of the substrate;

[0061] (4) depositing an indium tin oxide target on the treated layer 5 by magnetron sputtering in a high vacuum environment to form a conductive layer 4 with a square resistance of 200 Ω / □ and a thickness of 50 nm;

[0062] (5) The PTC slurry was screen-printed on the conductive layer 4 using a 300-mesh screen to prepare a PTC layer 3 with a thickness of about 800 μm, and the layer was dried in an oven at 120° C. for 40 minutes.

[0063] (6) On the other side of the substrate, a PEDOT:PSS solvent was spin-coated at a speed of 5000 r / min for 40 seconds to form a shielding layer 7 with a thickness of about 10 μm. The conductivity was increased by treating with 72% sulfuric acid, and the conductivity was 2974 Scm -1 .

[0064] (7) A metal foil with a thickness of 50 μm and conductive adhesive is prepared by laser etching to form interdigitated electrodes and attached to the PTC layer 3.

[0065] (8) Using a laminating device, the lower encapsulation layer 8 and the upper encapsulation layer 1 are respectively combined with the shielding layer 7 and the electrode layer 2 to perform hot-pressing roller lamination.

[0066] After connecting the shielding layer 7 with the wire, connect the electrode neutral line, and connect the live and zero power lines from the electrode, then it can be used. When used for heating, the covering time limit temperature is about 70±5℃, and it has a heat storage effect.

[0067] Example 2

[0068] A self-limiting temperature heating film comprises: a lower packaging layer, a shielding layer, a substrate layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer. The preparation method thereof comprises:

[0069] (1) 35 g of graphene powder was dispersed in 70 g of dimethylformamide (DMF), 90 g of acrylate and polyurethane emulsion were added thereto, and then 0.8 g of aluminum oxide, 8 g of titanium dioxide, 18 g of acrylic emulsion, and 19 g of ethanol were added in sequence and mechanically stirred to prepare a PTC slurry;

[0070] Steps (2) to (8) are the same as those in Example 1. When heated, the covering temperature is limited to about 70±5°C.

[0071] Example 3

[0072] A self-limiting temperature heating film comprises: a lower packaging layer, a shielding layer, a substrate layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer. The preparation method thereof comprises:

[0073] (1) After 10g paraffin wax and 0.5g sorbitan monooleate polyoxyethylene ether were melted at 65°C, 150ml deionized water was added at 2000r / min and dispersed for 5min. Then, a mixture of 0.3g silica, 6g copolymerized methyl methacrylate and 1g acrylic acid was added to obtain a phase change material. 25g graphene powder was dispersed in 60g dimethylformamide (DMF), and the obtained phase change material, 80g acrylate and polyurethane emulsion were added thereto. 0.6g aluminum oxide, 6g titanium dioxide, 15g acrylic emulsion, 18g ethanol were added in sequence and PTC slurry was prepared by ultrasonic dispersion.

[0074] (2) Clean both sides of the substrate with purified water and ethanol and then dry them thoroughly;

[0075] (3) Coating the polyester and silicon solution coating liquid on the surface of the substrate with a roller, and then drying it at 60°C to form a treatment layer of about 8 μm to increase the stability and flatness of the substrate;

[0076] (4) depositing an indium tin oxide target on the treated layer by magnetron sputtering in a high vacuum environment to form a conductive layer with a square resistance of 450 Ω / □ and a thickness of 30 nm;

[0077] (5) The PTC slurry was screen-printed on the conductive layer using a 150-mesh screen to prepare a PTC layer with a thickness of about 500 μm, and the layer was placed in an oven and dried at 80° C. for 60 minutes.

[0078] (6) On the other side of the substrate, a PEDOT:PSS solvent was spin-coated at a speed of 2000 r / min for 30 seconds to form a shielding layer with a thickness of about 3 μm, and then treated with 63% sulfuric acid to increase the conductivity.

[0079] (7) A metal foil with a thickness of 30 μm and conductive adhesive is prepared by laser etching to form interdigitated electrodes and bonded to the PTC layer.

[0080] (8) Using a laminating device, the lower packaging layer and the upper packaging layer are respectively combined with the shielding layer and the electrode layer to perform hot-pressing roller lamination.

[0081] After connecting the wire on the shielding layer, connect the electrode neutral wire, and connect the live and zero power lines from the electrode. Then it can be used. When used for heating, the covering time limit temperature is about 60±5℃, and it has a heat storage effect.

[0082] Example 4

[0083] A self-limiting temperature heating film comprises: a lower packaging layer, a shielding layer, a substrate layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer. The preparation method thereof comprises:

[0084] (1) After 20g of paraffin wax and 1g of sorbitan monooleate polyoxyethylene ether were melted at 65°C, 150ml of deionized water was added at a speed of 4000r / min, and dispersed for 15min. Then, a mixture of 0.8g of silicon dioxide, 10g of copolymerized methyl methacrylate and 5g of acrylic acid was added to obtain a phase change material. 50g of graphene powder was dispersed in 80g of dimethylformamide (DMF), and the obtained phase change material, 100g of acrylate and polyurethane emulsion were added thereto. Then, 10g of aluminum oxide, 10g of titanium dioxide, 20g of acrylic emulsion, 20g of ethanol, etc. were added in sequence and PTC slurry was prepared by ultrasonic dispersion.

[0085] (2) Clean both sides of the substrate with purified water and ethanol and then dry them thoroughly;

[0086] (3) Coating the polyester and silicon solution coating liquid on the surface of the substrate with a roller, and then drying it at 100°C to form a treatment layer of about 5 μm to increase the stability and flatness of the substrate;

[0087] (4) depositing an indium tin oxide target on the treated layer by magnetron sputtering in a high vacuum environment to form a conductive layer with a square resistance of 20Ω / □ and a thickness of 100nm;

[0088] (5) The PTC slurry was screen-printed on the conductive layer using a 500-mesh screen to prepare a PTC layer with a thickness of about 1000 μm, and the layer was placed in an oven and dried at 180° C. for 20 minutes.

[0089] (6) On the other side of the substrate, a PEDOT:PSS solvent was spin-coated at a speed of 10,000 r / min for 50 seconds to form a shielding layer with a thickness of 100 μm, and then treated with 55% sulfuric acid to increase the conductivity.

[0090] (7) A metal foil with a thickness of 100 μm and a conductive adhesive is prepared by laser etching to form interdigitated electrodes and bonded to the PTC layer.

[0091] (8) Using a laminating device, the lower packaging layer and the upper packaging layer are respectively combined with the shielding layer and the electrode layer to perform hot-pressing roller lamination.

[0092] After connecting the wire on the shielding layer, connect the electrode neutral wire, and connect the live and zero power lines from the electrode. Then it can be used. When used for heating, the covering time limit temperature is about 40±5℃, and it has a heat storage effect.

[0093] Example 5

[0094] The difference from Example 1 is that the heating film does not include a shielding layer, and its preparation method does not include the step of spin-coating the shielding layer. Finally, the lower packaging layer and the upper packaging layer are respectively combined with the substrate layer and the electrode layer for packaging and insulation.

[0095] Example 6

[0096] A self-limiting temperature heating film comprises: a lower packaging layer 8, a substrate layer 6, a processing layer 5, a conductive layer 4, a PTC layer 3, an electrode layer 2, a shielding layer 7 and an upper packaging layer 1, such as Figure 5 shown.

[0097] The preparation method thereof comprises:

[0098] (1) The preparation method of PTC slurry is the same as that of Example 1;

[0099] (2) Clean both sides of the substrate with purified water and ethanol and then dry them thoroughly;

[0100] (3) Coating the polyester and silicon solution coating liquid on the surface of the substrate with a roller, and then drying at 80°C to form a treatment layer 5 of about 6 μm to increase the stability and flatness of the substrate;

[0101] (4) depositing an indium tin oxide target on the treated layer 5 by magnetron sputtering in a high vacuum environment to form a conductive layer 4 with a square resistance of 200 Ω / □ and a thickness of 50 nm;

[0102] (5) The PTC slurry was screen-printed on the conductive layer 4 using a 300-mesh screen to prepare a PTC layer 3 with a thickness of about 800 μm, and the layer was dried in an oven at 120° C. for 40 minutes.

[0103] (6) A metal foil with a thickness of 50 μm and a conductive adhesive is prepared by laser etching to form an interdigitated electrode and attached to the PTC layer 3 to form the electrode layer 2.

[0104] (7) On the other side of the electrode layer 2, a PEDOT:PSS solvent was spin-coated at a speed of 5000 r / min for 40 seconds to form a shielding layer 7 with a thickness of about 10 μm. The conductivity was increased by treating with 72% sulfuric acid, and the conductivity was 2974 Scm -1 .

[0105] (8) Using a laminating device, the lower encapsulation layer 8 and the upper encapsulation layer 1 are respectively combined with the base material layer 6 and the shielding layer 7 to be laminated with a hot-pressing roller.

[0106] Connect the shielding layer 7 to the wire, then connect the electrode neutral line, and connect the live and neutral power lines from the electrode, and then you can use it.

[0107] Comparative Example 1

[0108] The difference from Example 1 is that the heating film includes: a lower packaging layer, a shielding layer, a substrate layer, a processing layer, a conductive layer, an electrode layer and an upper packaging layer, that is, the preparation process does not include the preparation of the PTC layer.

[0109] The heating film without PTC layer of comparative example 1 and the heating films with PTC layer of examples 1 and 2 of the same power were powered and a 10 cm thick cover was placed on the surface. Under the same heating conditions, a temperature probe was used to collect the temperature rise under the heating film cover. Figure 3 As shown in the figure, by comparison, it is found that the heating film with a PTC layer temperature limiting layer (Example 2) stops heating when the temperature rises to about 70°C, while the heating film without a PTC layer (Comparative Example 2) continues to heat up. Therefore, the heating film without a PTC layer will have a safety hazard when covered. After directly cutting off the power supply, Figure 4As shown, after the surface temperature of the PTC layer heating film containing phase change material (with heat storage function) (Example 1) is maintained for 40 minutes, the surface temperature of the heating film will gradually decrease, while the surface temperature of the heating film of Example 2 and Comparative Example 1 will gradually decrease from the beginning until it reaches room temperature.

[0110] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A self-limiting temperature heating film, characterized in that: It includes a lower packaging layer, a substrate layer, a processing layer, a conductive layer, a PTC layer, an electrode layer and an upper packaging layer arranged in sequence in the thickness direction; The PTC layer includes a phase change material.

2. The self-limiting temperature heating film according to claim 1, characterized in that: The thickness of the PTC layer is 500-1500 μm.

3. The self-temperature-limiting heating film according to claim 1, characterized in that: The invention also includes a shielding layer, which is arranged between the lower packaging layer and the substrate layer.

4. The self-temperature-limiting heating film according to claim 1, characterized in that: The invention also includes a shielding layer, which is arranged between the electrode layer and the upper packaging layer.

5. The self-limiting temperature heating film according to claim 3 or 4, characterized in that: The shielding layer includes a PEDOT:PSS film.

6. The self-limiting temperature heating film according to claim 3 or 4, characterized in that: The thickness of the shielding layer is 3-100 μm.

7. The self-temperature-limiting heating film according to claim 1, characterized in that: The thickness of the treatment layer is 1-8 μm.

8. The self-temperature-limiting heating film according to claim 1, characterized in that: The thickness of the conductive layer is 10-100 nm.

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